Commit | Line | Data |
---|---|---|
ddbcc7e8 | 1 | /* |
ddbcc7e8 PM |
2 | * Generic process-grouping system. |
3 | * | |
4 | * Based originally on the cpuset system, extracted by Paul Menage | |
5 | * Copyright (C) 2006 Google, Inc | |
6 | * | |
0dea1168 KS |
7 | * Notifications support |
8 | * Copyright (C) 2009 Nokia Corporation | |
9 | * Author: Kirill A. Shutemov | |
10 | * | |
ddbcc7e8 PM |
11 | * Copyright notices from the original cpuset code: |
12 | * -------------------------------------------------- | |
13 | * Copyright (C) 2003 BULL SA. | |
14 | * Copyright (C) 2004-2006 Silicon Graphics, Inc. | |
15 | * | |
16 | * Portions derived from Patrick Mochel's sysfs code. | |
17 | * sysfs is Copyright (c) 2001-3 Patrick Mochel | |
18 | * | |
19 | * 2003-10-10 Written by Simon Derr. | |
20 | * 2003-10-22 Updates by Stephen Hemminger. | |
21 | * 2004 May-July Rework by Paul Jackson. | |
22 | * --------------------------------------------------- | |
23 | * | |
24 | * This file is subject to the terms and conditions of the GNU General Public | |
25 | * License. See the file COPYING in the main directory of the Linux | |
26 | * distribution for more details. | |
27 | */ | |
28 | ||
ed3d261b JP |
29 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
30 | ||
ddbcc7e8 | 31 | #include <linux/cgroup.h> |
2ce9738b | 32 | #include <linux/cred.h> |
c6d57f33 | 33 | #include <linux/ctype.h> |
ddbcc7e8 | 34 | #include <linux/errno.h> |
2ce9738b | 35 | #include <linux/init_task.h> |
ddbcc7e8 PM |
36 | #include <linux/kernel.h> |
37 | #include <linux/list.h> | |
c9482a5b | 38 | #include <linux/magic.h> |
ddbcc7e8 PM |
39 | #include <linux/mm.h> |
40 | #include <linux/mutex.h> | |
41 | #include <linux/mount.h> | |
42 | #include <linux/pagemap.h> | |
a424316c | 43 | #include <linux/proc_fs.h> |
ddbcc7e8 PM |
44 | #include <linux/rcupdate.h> |
45 | #include <linux/sched.h> | |
ddbcc7e8 | 46 | #include <linux/slab.h> |
ddbcc7e8 | 47 | #include <linux/spinlock.h> |
96d365e0 | 48 | #include <linux/rwsem.h> |
1ed13287 | 49 | #include <linux/percpu-rwsem.h> |
ddbcc7e8 | 50 | #include <linux/string.h> |
bbcb81d0 | 51 | #include <linux/sort.h> |
81a6a5cd | 52 | #include <linux/kmod.h> |
846c7bb0 BS |
53 | #include <linux/delayacct.h> |
54 | #include <linux/cgroupstats.h> | |
0ac801fe | 55 | #include <linux/hashtable.h> |
096b7fe0 | 56 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 57 | #include <linux/idr.h> |
d1d9fd33 | 58 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
c4c27fbd | 59 | #include <linux/kthread.h> |
776f02fa | 60 | #include <linux/delay.h> |
846c7bb0 | 61 | |
60063497 | 62 | #include <linux/atomic.h> |
ddbcc7e8 | 63 | |
b1a21367 TH |
64 | /* |
65 | * pidlists linger the following amount before being destroyed. The goal | |
66 | * is avoiding frequent destruction in the middle of consecutive read calls | |
67 | * Expiring in the middle is a performance problem not a correctness one. | |
68 | * 1 sec should be enough. | |
69 | */ | |
70 | #define CGROUP_PIDLIST_DESTROY_DELAY HZ | |
71 | ||
8d7e6fb0 TH |
72 | #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
73 | MAX_CFTYPE_NAME + 2) | |
74 | ||
e25e2cbb TH |
75 | /* |
76 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
77 | * hierarchy must be performed while holding it. | |
78 | * | |
0e1d768f TH |
79 | * css_set_rwsem protects task->cgroups pointer, the list of css_set |
80 | * objects, and the chain of tasks off each css_set. | |
e25e2cbb | 81 | * |
0e1d768f TH |
82 | * These locks are exported if CONFIG_PROVE_RCU so that accessors in |
83 | * cgroup.h can use them for lockdep annotations. | |
e25e2cbb | 84 | */ |
2219449a TH |
85 | #ifdef CONFIG_PROVE_RCU |
86 | DEFINE_MUTEX(cgroup_mutex); | |
0e1d768f TH |
87 | DECLARE_RWSEM(css_set_rwsem); |
88 | EXPORT_SYMBOL_GPL(cgroup_mutex); | |
89 | EXPORT_SYMBOL_GPL(css_set_rwsem); | |
2219449a | 90 | #else |
81a6a5cd | 91 | static DEFINE_MUTEX(cgroup_mutex); |
0e1d768f | 92 | static DECLARE_RWSEM(css_set_rwsem); |
2219449a TH |
93 | #endif |
94 | ||
6fa4918d | 95 | /* |
15a4c835 TH |
96 | * Protects cgroup_idr and css_idr so that IDs can be released without |
97 | * grabbing cgroup_mutex. | |
6fa4918d TH |
98 | */ |
99 | static DEFINE_SPINLOCK(cgroup_idr_lock); | |
100 | ||
69e943b7 TH |
101 | /* |
102 | * Protects cgroup_subsys->release_agent_path. Modifying it also requires | |
103 | * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. | |
104 | */ | |
105 | static DEFINE_SPINLOCK(release_agent_path_lock); | |
81a6a5cd | 106 | |
1ed13287 TH |
107 | struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
108 | ||
8353da1f | 109 | #define cgroup_assert_mutex_or_rcu_locked() \ |
f78f5b90 PM |
110 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
111 | !lockdep_is_held(&cgroup_mutex), \ | |
8353da1f | 112 | "cgroup_mutex or RCU read lock required"); |
780cd8b3 | 113 | |
e5fca243 TH |
114 | /* |
115 | * cgroup destruction makes heavy use of work items and there can be a lot | |
116 | * of concurrent destructions. Use a separate workqueue so that cgroup | |
117 | * destruction work items don't end up filling up max_active of system_wq | |
118 | * which may lead to deadlock. | |
119 | */ | |
120 | static struct workqueue_struct *cgroup_destroy_wq; | |
121 | ||
b1a21367 TH |
122 | /* |
123 | * pidlist destructions need to be flushed on cgroup destruction. Use a | |
124 | * separate workqueue as flush domain. | |
125 | */ | |
126 | static struct workqueue_struct *cgroup_pidlist_destroy_wq; | |
127 | ||
3ed80a62 | 128 | /* generate an array of cgroup subsystem pointers */ |
073219e9 | 129 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
3ed80a62 | 130 | static struct cgroup_subsys *cgroup_subsys[] = { |
ddbcc7e8 PM |
131 | #include <linux/cgroup_subsys.h> |
132 | }; | |
073219e9 TH |
133 | #undef SUBSYS |
134 | ||
135 | /* array of cgroup subsystem names */ | |
136 | #define SUBSYS(_x) [_x ## _cgrp_id] = #_x, | |
137 | static const char *cgroup_subsys_name[] = { | |
ddbcc7e8 PM |
138 | #include <linux/cgroup_subsys.h> |
139 | }; | |
073219e9 | 140 | #undef SUBSYS |
ddbcc7e8 | 141 | |
49d1dc4b TH |
142 | /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */ |
143 | #define SUBSYS(_x) \ | |
144 | DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \ | |
145 | DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \ | |
146 | EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \ | |
147 | EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key); | |
148 | #include <linux/cgroup_subsys.h> | |
149 | #undef SUBSYS | |
150 | ||
151 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key, | |
152 | static struct static_key_true *cgroup_subsys_enabled_key[] = { | |
153 | #include <linux/cgroup_subsys.h> | |
154 | }; | |
155 | #undef SUBSYS | |
156 | ||
157 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key, | |
158 | static struct static_key_true *cgroup_subsys_on_dfl_key[] = { | |
159 | #include <linux/cgroup_subsys.h> | |
160 | }; | |
161 | #undef SUBSYS | |
162 | ||
ddbcc7e8 | 163 | /* |
3dd06ffa | 164 | * The default hierarchy, reserved for the subsystems that are otherwise |
9871bf95 TH |
165 | * unattached - it never has more than a single cgroup, and all tasks are |
166 | * part of that cgroup. | |
ddbcc7e8 | 167 | */ |
a2dd4247 | 168 | struct cgroup_root cgrp_dfl_root; |
d0ec4230 | 169 | EXPORT_SYMBOL_GPL(cgrp_dfl_root); |
9871bf95 | 170 | |
a2dd4247 TH |
171 | /* |
172 | * The default hierarchy always exists but is hidden until mounted for the | |
173 | * first time. This is for backward compatibility. | |
174 | */ | |
175 | static bool cgrp_dfl_root_visible; | |
ddbcc7e8 | 176 | |
a8ddc821 TH |
177 | /* |
178 | * Set by the boot param of the same name and makes subsystems with NULL | |
179 | * ->dfl_files to use ->legacy_files on the default hierarchy. | |
180 | */ | |
181 | static bool cgroup_legacy_files_on_dfl; | |
182 | ||
5533e011 | 183 | /* some controllers are not supported in the default hierarchy */ |
8ab456ac | 184 | static unsigned long cgrp_dfl_root_inhibit_ss_mask; |
5533e011 | 185 | |
ddbcc7e8 PM |
186 | /* The list of hierarchy roots */ |
187 | ||
9871bf95 TH |
188 | static LIST_HEAD(cgroup_roots); |
189 | static int cgroup_root_count; | |
ddbcc7e8 | 190 | |
3417ae1f | 191 | /* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
1a574231 | 192 | static DEFINE_IDR(cgroup_hierarchy_idr); |
2c6ab6d2 | 193 | |
794611a1 | 194 | /* |
0cb51d71 TH |
195 | * Assign a monotonically increasing serial number to csses. It guarantees |
196 | * cgroups with bigger numbers are newer than those with smaller numbers. | |
197 | * Also, as csses are always appended to the parent's ->children list, it | |
198 | * guarantees that sibling csses are always sorted in the ascending serial | |
199 | * number order on the list. Protected by cgroup_mutex. | |
794611a1 | 200 | */ |
0cb51d71 | 201 | static u64 css_serial_nr_next = 1; |
794611a1 | 202 | |
cb4a3167 AS |
203 | /* |
204 | * These bitmask flags indicate whether tasks in the fork and exit paths have | |
205 | * fork/exit handlers to call. This avoids us having to do extra work in the | |
206 | * fork/exit path to check which subsystems have fork/exit callbacks. | |
ddbcc7e8 | 207 | */ |
cb4a3167 AS |
208 | static unsigned long have_fork_callback __read_mostly; |
209 | static unsigned long have_exit_callback __read_mostly; | |
ddbcc7e8 | 210 | |
7e47682e AS |
211 | /* Ditto for the can_fork callback. */ |
212 | static unsigned long have_canfork_callback __read_mostly; | |
213 | ||
a14c6874 TH |
214 | static struct cftype cgroup_dfl_base_files[]; |
215 | static struct cftype cgroup_legacy_base_files[]; | |
628f7cd4 | 216 | |
3dd06ffa | 217 | static int rebind_subsystems(struct cgroup_root *dst_root, |
8ab456ac | 218 | unsigned long ss_mask); |
42809dd4 | 219 | static int cgroup_destroy_locked(struct cgroup *cgrp); |
f63070d3 TH |
220 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, |
221 | bool visible); | |
9d755d33 | 222 | static void css_release(struct percpu_ref *ref); |
f8f22e53 | 223 | static void kill_css(struct cgroup_subsys_state *css); |
4df8dc90 TH |
224 | static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
225 | struct cgroup *cgrp, struct cftype cfts[], | |
2bb566cb | 226 | bool is_add); |
42809dd4 | 227 | |
fc5ed1e9 TH |
228 | /** |
229 | * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID | |
230 | * @ssid: subsys ID of interest | |
231 | * | |
232 | * cgroup_subsys_enabled() can only be used with literal subsys names which | |
233 | * is fine for individual subsystems but unsuitable for cgroup core. This | |
234 | * is slower static_key_enabled() based test indexed by @ssid. | |
235 | */ | |
236 | static bool cgroup_ssid_enabled(int ssid) | |
237 | { | |
238 | return static_key_enabled(cgroup_subsys_enabled_key[ssid]); | |
239 | } | |
240 | ||
9e10a130 TH |
241 | /** |
242 | * cgroup_on_dfl - test whether a cgroup is on the default hierarchy | |
243 | * @cgrp: the cgroup of interest | |
244 | * | |
245 | * The default hierarchy is the v2 interface of cgroup and this function | |
246 | * can be used to test whether a cgroup is on the default hierarchy for | |
247 | * cases where a subsystem should behave differnetly depending on the | |
248 | * interface version. | |
249 | * | |
250 | * The set of behaviors which change on the default hierarchy are still | |
251 | * being determined and the mount option is prefixed with __DEVEL__. | |
252 | * | |
253 | * List of changed behaviors: | |
254 | * | |
255 | * - Mount options "noprefix", "xattr", "clone_children", "release_agent" | |
256 | * and "name" are disallowed. | |
257 | * | |
258 | * - When mounting an existing superblock, mount options should match. | |
259 | * | |
260 | * - Remount is disallowed. | |
261 | * | |
262 | * - rename(2) is disallowed. | |
263 | * | |
264 | * - "tasks" is removed. Everything should be at process granularity. Use | |
265 | * "cgroup.procs" instead. | |
266 | * | |
267 | * - "cgroup.procs" is not sorted. pids will be unique unless they got | |
268 | * recycled inbetween reads. | |
269 | * | |
270 | * - "release_agent" and "notify_on_release" are removed. Replacement | |
271 | * notification mechanism will be implemented. | |
272 | * | |
273 | * - "cgroup.clone_children" is removed. | |
274 | * | |
275 | * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup | |
276 | * and its descendants contain no task; otherwise, 1. The file also | |
277 | * generates kernfs notification which can be monitored through poll and | |
278 | * [di]notify when the value of the file changes. | |
279 | * | |
280 | * - cpuset: tasks will be kept in empty cpusets when hotplug happens and | |
281 | * take masks of ancestors with non-empty cpus/mems, instead of being | |
282 | * moved to an ancestor. | |
283 | * | |
284 | * - cpuset: a task can be moved into an empty cpuset, and again it takes | |
285 | * masks of ancestors. | |
286 | * | |
287 | * - memcg: use_hierarchy is on by default and the cgroup file for the flag | |
288 | * is not created. | |
289 | * | |
290 | * - blkcg: blk-throttle becomes properly hierarchical. | |
291 | * | |
292 | * - debug: disallowed on the default hierarchy. | |
293 | */ | |
294 | static bool cgroup_on_dfl(const struct cgroup *cgrp) | |
295 | { | |
296 | return cgrp->root == &cgrp_dfl_root; | |
297 | } | |
298 | ||
6fa4918d TH |
299 | /* IDR wrappers which synchronize using cgroup_idr_lock */ |
300 | static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, | |
301 | gfp_t gfp_mask) | |
302 | { | |
303 | int ret; | |
304 | ||
305 | idr_preload(gfp_mask); | |
54504e97 | 306 | spin_lock_bh(&cgroup_idr_lock); |
cf780b7d | 307 | ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_WAIT); |
54504e97 | 308 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
309 | idr_preload_end(); |
310 | return ret; | |
311 | } | |
312 | ||
313 | static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) | |
314 | { | |
315 | void *ret; | |
316 | ||
54504e97 | 317 | spin_lock_bh(&cgroup_idr_lock); |
6fa4918d | 318 | ret = idr_replace(idr, ptr, id); |
54504e97 | 319 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
320 | return ret; |
321 | } | |
322 | ||
323 | static void cgroup_idr_remove(struct idr *idr, int id) | |
324 | { | |
54504e97 | 325 | spin_lock_bh(&cgroup_idr_lock); |
6fa4918d | 326 | idr_remove(idr, id); |
54504e97 | 327 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
328 | } |
329 | ||
d51f39b0 TH |
330 | static struct cgroup *cgroup_parent(struct cgroup *cgrp) |
331 | { | |
332 | struct cgroup_subsys_state *parent_css = cgrp->self.parent; | |
333 | ||
334 | if (parent_css) | |
335 | return container_of(parent_css, struct cgroup, self); | |
336 | return NULL; | |
337 | } | |
338 | ||
95109b62 TH |
339 | /** |
340 | * cgroup_css - obtain a cgroup's css for the specified subsystem | |
341 | * @cgrp: the cgroup of interest | |
9d800df1 | 342 | * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
95109b62 | 343 | * |
ca8bdcaf TH |
344 | * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
345 | * function must be called either under cgroup_mutex or rcu_read_lock() and | |
346 | * the caller is responsible for pinning the returned css if it wants to | |
347 | * keep accessing it outside the said locks. This function may return | |
348 | * %NULL if @cgrp doesn't have @subsys_id enabled. | |
95109b62 TH |
349 | */ |
350 | static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, | |
ca8bdcaf | 351 | struct cgroup_subsys *ss) |
95109b62 | 352 | { |
ca8bdcaf | 353 | if (ss) |
aec25020 | 354 | return rcu_dereference_check(cgrp->subsys[ss->id], |
ace2bee8 | 355 | lockdep_is_held(&cgroup_mutex)); |
ca8bdcaf | 356 | else |
9d800df1 | 357 | return &cgrp->self; |
95109b62 | 358 | } |
42809dd4 | 359 | |
aec3dfcb TH |
360 | /** |
361 | * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem | |
362 | * @cgrp: the cgroup of interest | |
9d800df1 | 363 | * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
aec3dfcb | 364 | * |
d0f702e6 | 365 | * Similar to cgroup_css() but returns the effective css, which is defined |
aec3dfcb TH |
366 | * as the matching css of the nearest ancestor including self which has @ss |
367 | * enabled. If @ss is associated with the hierarchy @cgrp is on, this | |
368 | * function is guaranteed to return non-NULL css. | |
369 | */ | |
370 | static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, | |
371 | struct cgroup_subsys *ss) | |
372 | { | |
373 | lockdep_assert_held(&cgroup_mutex); | |
374 | ||
375 | if (!ss) | |
9d800df1 | 376 | return &cgrp->self; |
aec3dfcb TH |
377 | |
378 | if (!(cgrp->root->subsys_mask & (1 << ss->id))) | |
379 | return NULL; | |
380 | ||
eeecbd19 TH |
381 | /* |
382 | * This function is used while updating css associations and thus | |
383 | * can't test the csses directly. Use ->child_subsys_mask. | |
384 | */ | |
d51f39b0 TH |
385 | while (cgroup_parent(cgrp) && |
386 | !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ss->id))) | |
387 | cgrp = cgroup_parent(cgrp); | |
aec3dfcb TH |
388 | |
389 | return cgroup_css(cgrp, ss); | |
95109b62 | 390 | } |
42809dd4 | 391 | |
eeecbd19 TH |
392 | /** |
393 | * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem | |
394 | * @cgrp: the cgroup of interest | |
395 | * @ss: the subsystem of interest | |
396 | * | |
397 | * Find and get the effective css of @cgrp for @ss. The effective css is | |
398 | * defined as the matching css of the nearest ancestor including self which | |
399 | * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on, | |
400 | * the root css is returned, so this function always returns a valid css. | |
401 | * The returned css must be put using css_put(). | |
402 | */ | |
403 | struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp, | |
404 | struct cgroup_subsys *ss) | |
405 | { | |
406 | struct cgroup_subsys_state *css; | |
407 | ||
408 | rcu_read_lock(); | |
409 | ||
410 | do { | |
411 | css = cgroup_css(cgrp, ss); | |
412 | ||
413 | if (css && css_tryget_online(css)) | |
414 | goto out_unlock; | |
415 | cgrp = cgroup_parent(cgrp); | |
416 | } while (cgrp); | |
417 | ||
418 | css = init_css_set.subsys[ss->id]; | |
419 | css_get(css); | |
420 | out_unlock: | |
421 | rcu_read_unlock(); | |
422 | return css; | |
423 | } | |
424 | ||
ddbcc7e8 | 425 | /* convenient tests for these bits */ |
54766d4a | 426 | static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
ddbcc7e8 | 427 | { |
184faf32 | 428 | return !(cgrp->self.flags & CSS_ONLINE); |
ddbcc7e8 PM |
429 | } |
430 | ||
b4168640 | 431 | struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) |
59f5296b | 432 | { |
2bd59d48 | 433 | struct cgroup *cgrp = of->kn->parent->priv; |
b4168640 | 434 | struct cftype *cft = of_cft(of); |
2bd59d48 TH |
435 | |
436 | /* | |
437 | * This is open and unprotected implementation of cgroup_css(). | |
438 | * seq_css() is only called from a kernfs file operation which has | |
439 | * an active reference on the file. Because all the subsystem | |
440 | * files are drained before a css is disassociated with a cgroup, | |
441 | * the matching css from the cgroup's subsys table is guaranteed to | |
442 | * be and stay valid until the enclosing operation is complete. | |
443 | */ | |
444 | if (cft->ss) | |
445 | return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); | |
446 | else | |
9d800df1 | 447 | return &cgrp->self; |
59f5296b | 448 | } |
b4168640 | 449 | EXPORT_SYMBOL_GPL(of_css); |
59f5296b | 450 | |
78574cf9 LZ |
451 | /** |
452 | * cgroup_is_descendant - test ancestry | |
453 | * @cgrp: the cgroup to be tested | |
454 | * @ancestor: possible ancestor of @cgrp | |
455 | * | |
456 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true | |
457 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp | |
458 | * and @ancestor are accessible. | |
459 | */ | |
460 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) | |
461 | { | |
462 | while (cgrp) { | |
463 | if (cgrp == ancestor) | |
464 | return true; | |
d51f39b0 | 465 | cgrp = cgroup_parent(cgrp); |
78574cf9 LZ |
466 | } |
467 | return false; | |
468 | } | |
ddbcc7e8 | 469 | |
e9685a03 | 470 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 471 | { |
bd89aabc | 472 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
473 | } |
474 | ||
1c6727af TH |
475 | /** |
476 | * for_each_css - iterate all css's of a cgroup | |
477 | * @css: the iteration cursor | |
478 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
479 | * @cgrp: the target cgroup to iterate css's of | |
480 | * | |
aec3dfcb | 481 | * Should be called under cgroup_[tree_]mutex. |
1c6727af TH |
482 | */ |
483 | #define for_each_css(css, ssid, cgrp) \ | |
484 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
485 | if (!((css) = rcu_dereference_check( \ | |
486 | (cgrp)->subsys[(ssid)], \ | |
487 | lockdep_is_held(&cgroup_mutex)))) { } \ | |
488 | else | |
489 | ||
aec3dfcb TH |
490 | /** |
491 | * for_each_e_css - iterate all effective css's of a cgroup | |
492 | * @css: the iteration cursor | |
493 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
494 | * @cgrp: the target cgroup to iterate css's of | |
495 | * | |
496 | * Should be called under cgroup_[tree_]mutex. | |
497 | */ | |
498 | #define for_each_e_css(css, ssid, cgrp) \ | |
499 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
500 | if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \ | |
501 | ; \ | |
502 | else | |
503 | ||
30159ec7 | 504 | /** |
3ed80a62 | 505 | * for_each_subsys - iterate all enabled cgroup subsystems |
30159ec7 | 506 | * @ss: the iteration cursor |
780cd8b3 | 507 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
30159ec7 | 508 | */ |
780cd8b3 | 509 | #define for_each_subsys(ss, ssid) \ |
3ed80a62 TH |
510 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ |
511 | (((ss) = cgroup_subsys[ssid]) || true); (ssid)++) | |
30159ec7 | 512 | |
cb4a3167 AS |
513 | /** |
514 | * for_each_subsys_which - filter for_each_subsys with a bitmask | |
515 | * @ss: the iteration cursor | |
516 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end | |
517 | * @ss_maskp: a pointer to the bitmask | |
518 | * | |
519 | * The block will only run for cases where the ssid-th bit (1 << ssid) of | |
520 | * mask is set to 1. | |
521 | */ | |
522 | #define for_each_subsys_which(ss, ssid, ss_maskp) \ | |
523 | if (!CGROUP_SUBSYS_COUNT) /* to avoid spurious gcc warning */ \ | |
4a705c5c | 524 | (ssid) = 0; \ |
cb4a3167 AS |
525 | else \ |
526 | for_each_set_bit(ssid, ss_maskp, CGROUP_SUBSYS_COUNT) \ | |
527 | if (((ss) = cgroup_subsys[ssid]) && false) \ | |
528 | break; \ | |
529 | else | |
530 | ||
985ed670 TH |
531 | /* iterate across the hierarchies */ |
532 | #define for_each_root(root) \ | |
5549c497 | 533 | list_for_each_entry((root), &cgroup_roots, root_list) |
ddbcc7e8 | 534 | |
f8f22e53 TH |
535 | /* iterate over child cgrps, lock should be held throughout iteration */ |
536 | #define cgroup_for_each_live_child(child, cgrp) \ | |
d5c419b6 | 537 | list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \ |
8353da1f | 538 | if (({ lockdep_assert_held(&cgroup_mutex); \ |
f8f22e53 TH |
539 | cgroup_is_dead(child); })) \ |
540 | ; \ | |
541 | else | |
7ae1bad9 | 542 | |
81a6a5cd | 543 | static void cgroup_release_agent(struct work_struct *work); |
bd89aabc | 544 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 545 | |
69d0206c TH |
546 | /* |
547 | * A cgroup can be associated with multiple css_sets as different tasks may | |
548 | * belong to different cgroups on different hierarchies. In the other | |
549 | * direction, a css_set is naturally associated with multiple cgroups. | |
550 | * This M:N relationship is represented by the following link structure | |
551 | * which exists for each association and allows traversing the associations | |
552 | * from both sides. | |
553 | */ | |
554 | struct cgrp_cset_link { | |
555 | /* the cgroup and css_set this link associates */ | |
556 | struct cgroup *cgrp; | |
557 | struct css_set *cset; | |
558 | ||
559 | /* list of cgrp_cset_links anchored at cgrp->cset_links */ | |
560 | struct list_head cset_link; | |
561 | ||
562 | /* list of cgrp_cset_links anchored at css_set->cgrp_links */ | |
563 | struct list_head cgrp_link; | |
817929ec PM |
564 | }; |
565 | ||
172a2c06 TH |
566 | /* |
567 | * The default css_set - used by init and its children prior to any | |
817929ec PM |
568 | * hierarchies being mounted. It contains a pointer to the root state |
569 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
570 | * reference-counted, to improve performance when child cgroups | |
571 | * haven't been created. | |
572 | */ | |
5024ae29 | 573 | struct css_set init_css_set = { |
172a2c06 TH |
574 | .refcount = ATOMIC_INIT(1), |
575 | .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), | |
576 | .tasks = LIST_HEAD_INIT(init_css_set.tasks), | |
577 | .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), | |
578 | .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), | |
579 | .mg_node = LIST_HEAD_INIT(init_css_set.mg_node), | |
580 | }; | |
817929ec | 581 | |
172a2c06 | 582 | static int css_set_count = 1; /* 1 for init_css_set */ |
817929ec | 583 | |
842b597e TH |
584 | /** |
585 | * cgroup_update_populated - updated populated count of a cgroup | |
586 | * @cgrp: the target cgroup | |
587 | * @populated: inc or dec populated count | |
588 | * | |
589 | * @cgrp is either getting the first task (css_set) or losing the last. | |
590 | * Update @cgrp->populated_cnt accordingly. The count is propagated | |
591 | * towards root so that a given cgroup's populated_cnt is zero iff the | |
592 | * cgroup and all its descendants are empty. | |
593 | * | |
594 | * @cgrp's interface file "cgroup.populated" is zero if | |
595 | * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt | |
596 | * changes from or to zero, userland is notified that the content of the | |
597 | * interface file has changed. This can be used to detect when @cgrp and | |
598 | * its descendants become populated or empty. | |
599 | */ | |
600 | static void cgroup_update_populated(struct cgroup *cgrp, bool populated) | |
601 | { | |
602 | lockdep_assert_held(&css_set_rwsem); | |
603 | ||
604 | do { | |
605 | bool trigger; | |
606 | ||
607 | if (populated) | |
608 | trigger = !cgrp->populated_cnt++; | |
609 | else | |
610 | trigger = !--cgrp->populated_cnt; | |
611 | ||
612 | if (!trigger) | |
613 | break; | |
614 | ||
6f60eade TH |
615 | cgroup_file_notify(&cgrp->events_file); |
616 | ||
d51f39b0 | 617 | cgrp = cgroup_parent(cgrp); |
842b597e TH |
618 | } while (cgrp); |
619 | } | |
620 | ||
7717f7ba PM |
621 | /* |
622 | * hash table for cgroup groups. This improves the performance to find | |
623 | * an existing css_set. This hash doesn't (currently) take into | |
624 | * account cgroups in empty hierarchies. | |
625 | */ | |
472b1053 | 626 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 627 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 628 | |
0ac801fe | 629 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 | 630 | { |
0ac801fe | 631 | unsigned long key = 0UL; |
30159ec7 TH |
632 | struct cgroup_subsys *ss; |
633 | int i; | |
472b1053 | 634 | |
30159ec7 | 635 | for_each_subsys(ss, i) |
0ac801fe LZ |
636 | key += (unsigned long)css[i]; |
637 | key = (key >> 16) ^ key; | |
472b1053 | 638 | |
0ac801fe | 639 | return key; |
472b1053 LZ |
640 | } |
641 | ||
a25eb52e | 642 | static void put_css_set_locked(struct css_set *cset) |
b4f48b63 | 643 | { |
69d0206c | 644 | struct cgrp_cset_link *link, *tmp_link; |
2d8f243a TH |
645 | struct cgroup_subsys *ss; |
646 | int ssid; | |
5abb8855 | 647 | |
89c5509b TH |
648 | lockdep_assert_held(&css_set_rwsem); |
649 | ||
650 | if (!atomic_dec_and_test(&cset->refcount)) | |
146aa1bd | 651 | return; |
81a6a5cd | 652 | |
2c6ab6d2 | 653 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
2d8f243a TH |
654 | for_each_subsys(ss, ssid) |
655 | list_del(&cset->e_cset_node[ssid]); | |
5abb8855 | 656 | hash_del(&cset->hlist); |
2c6ab6d2 PM |
657 | css_set_count--; |
658 | ||
69d0206c | 659 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
2c6ab6d2 | 660 | struct cgroup *cgrp = link->cgrp; |
5abb8855 | 661 | |
69d0206c TH |
662 | list_del(&link->cset_link); |
663 | list_del(&link->cgrp_link); | |
71b5707e | 664 | |
96d365e0 | 665 | /* @cgrp can't go away while we're holding css_set_rwsem */ |
842b597e TH |
666 | if (list_empty(&cgrp->cset_links)) { |
667 | cgroup_update_populated(cgrp, false); | |
a25eb52e | 668 | check_for_release(cgrp); |
81a6a5cd | 669 | } |
2c6ab6d2 PM |
670 | |
671 | kfree(link); | |
81a6a5cd | 672 | } |
2c6ab6d2 | 673 | |
5abb8855 | 674 | kfree_rcu(cset, rcu_head); |
b4f48b63 PM |
675 | } |
676 | ||
a25eb52e | 677 | static void put_css_set(struct css_set *cset) |
89c5509b TH |
678 | { |
679 | /* | |
680 | * Ensure that the refcount doesn't hit zero while any readers | |
681 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
682 | * rwlock | |
683 | */ | |
684 | if (atomic_add_unless(&cset->refcount, -1, 1)) | |
685 | return; | |
686 | ||
687 | down_write(&css_set_rwsem); | |
a25eb52e | 688 | put_css_set_locked(cset); |
89c5509b TH |
689 | up_write(&css_set_rwsem); |
690 | } | |
691 | ||
817929ec PM |
692 | /* |
693 | * refcounted get/put for css_set objects | |
694 | */ | |
5abb8855 | 695 | static inline void get_css_set(struct css_set *cset) |
817929ec | 696 | { |
5abb8855 | 697 | atomic_inc(&cset->refcount); |
817929ec PM |
698 | } |
699 | ||
b326f9d0 | 700 | /** |
7717f7ba | 701 | * compare_css_sets - helper function for find_existing_css_set(). |
5abb8855 TH |
702 | * @cset: candidate css_set being tested |
703 | * @old_cset: existing css_set for a task | |
7717f7ba PM |
704 | * @new_cgrp: cgroup that's being entered by the task |
705 | * @template: desired set of css pointers in css_set (pre-calculated) | |
706 | * | |
6f4b7e63 | 707 | * Returns true if "cset" matches "old_cset" except for the hierarchy |
7717f7ba PM |
708 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
709 | */ | |
5abb8855 TH |
710 | static bool compare_css_sets(struct css_set *cset, |
711 | struct css_set *old_cset, | |
7717f7ba PM |
712 | struct cgroup *new_cgrp, |
713 | struct cgroup_subsys_state *template[]) | |
714 | { | |
715 | struct list_head *l1, *l2; | |
716 | ||
aec3dfcb TH |
717 | /* |
718 | * On the default hierarchy, there can be csets which are | |
719 | * associated with the same set of cgroups but different csses. | |
720 | * Let's first ensure that csses match. | |
721 | */ | |
722 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) | |
7717f7ba | 723 | return false; |
7717f7ba PM |
724 | |
725 | /* | |
726 | * Compare cgroup pointers in order to distinguish between | |
aec3dfcb TH |
727 | * different cgroups in hierarchies. As different cgroups may |
728 | * share the same effective css, this comparison is always | |
729 | * necessary. | |
7717f7ba | 730 | */ |
69d0206c TH |
731 | l1 = &cset->cgrp_links; |
732 | l2 = &old_cset->cgrp_links; | |
7717f7ba | 733 | while (1) { |
69d0206c | 734 | struct cgrp_cset_link *link1, *link2; |
5abb8855 | 735 | struct cgroup *cgrp1, *cgrp2; |
7717f7ba PM |
736 | |
737 | l1 = l1->next; | |
738 | l2 = l2->next; | |
739 | /* See if we reached the end - both lists are equal length. */ | |
69d0206c TH |
740 | if (l1 == &cset->cgrp_links) { |
741 | BUG_ON(l2 != &old_cset->cgrp_links); | |
7717f7ba PM |
742 | break; |
743 | } else { | |
69d0206c | 744 | BUG_ON(l2 == &old_cset->cgrp_links); |
7717f7ba PM |
745 | } |
746 | /* Locate the cgroups associated with these links. */ | |
69d0206c TH |
747 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
748 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); | |
749 | cgrp1 = link1->cgrp; | |
750 | cgrp2 = link2->cgrp; | |
7717f7ba | 751 | /* Hierarchies should be linked in the same order. */ |
5abb8855 | 752 | BUG_ON(cgrp1->root != cgrp2->root); |
7717f7ba PM |
753 | |
754 | /* | |
755 | * If this hierarchy is the hierarchy of the cgroup | |
756 | * that's changing, then we need to check that this | |
757 | * css_set points to the new cgroup; if it's any other | |
758 | * hierarchy, then this css_set should point to the | |
759 | * same cgroup as the old css_set. | |
760 | */ | |
5abb8855 TH |
761 | if (cgrp1->root == new_cgrp->root) { |
762 | if (cgrp1 != new_cgrp) | |
7717f7ba PM |
763 | return false; |
764 | } else { | |
5abb8855 | 765 | if (cgrp1 != cgrp2) |
7717f7ba PM |
766 | return false; |
767 | } | |
768 | } | |
769 | return true; | |
770 | } | |
771 | ||
b326f9d0 TH |
772 | /** |
773 | * find_existing_css_set - init css array and find the matching css_set | |
774 | * @old_cset: the css_set that we're using before the cgroup transition | |
775 | * @cgrp: the cgroup that we're moving into | |
776 | * @template: out param for the new set of csses, should be clear on entry | |
817929ec | 777 | */ |
5abb8855 TH |
778 | static struct css_set *find_existing_css_set(struct css_set *old_cset, |
779 | struct cgroup *cgrp, | |
780 | struct cgroup_subsys_state *template[]) | |
b4f48b63 | 781 | { |
3dd06ffa | 782 | struct cgroup_root *root = cgrp->root; |
30159ec7 | 783 | struct cgroup_subsys *ss; |
5abb8855 | 784 | struct css_set *cset; |
0ac801fe | 785 | unsigned long key; |
b326f9d0 | 786 | int i; |
817929ec | 787 | |
aae8aab4 BB |
788 | /* |
789 | * Build the set of subsystem state objects that we want to see in the | |
790 | * new css_set. while subsystems can change globally, the entries here | |
791 | * won't change, so no need for locking. | |
792 | */ | |
30159ec7 | 793 | for_each_subsys(ss, i) { |
f392e51c | 794 | if (root->subsys_mask & (1UL << i)) { |
aec3dfcb TH |
795 | /* |
796 | * @ss is in this hierarchy, so we want the | |
797 | * effective css from @cgrp. | |
798 | */ | |
799 | template[i] = cgroup_e_css(cgrp, ss); | |
817929ec | 800 | } else { |
aec3dfcb TH |
801 | /* |
802 | * @ss is not in this hierarchy, so we don't want | |
803 | * to change the css. | |
804 | */ | |
5abb8855 | 805 | template[i] = old_cset->subsys[i]; |
817929ec PM |
806 | } |
807 | } | |
808 | ||
0ac801fe | 809 | key = css_set_hash(template); |
5abb8855 TH |
810 | hash_for_each_possible(css_set_table, cset, hlist, key) { |
811 | if (!compare_css_sets(cset, old_cset, cgrp, template)) | |
7717f7ba PM |
812 | continue; |
813 | ||
814 | /* This css_set matches what we need */ | |
5abb8855 | 815 | return cset; |
472b1053 | 816 | } |
817929ec PM |
817 | |
818 | /* No existing cgroup group matched */ | |
819 | return NULL; | |
820 | } | |
821 | ||
69d0206c | 822 | static void free_cgrp_cset_links(struct list_head *links_to_free) |
36553434 | 823 | { |
69d0206c | 824 | struct cgrp_cset_link *link, *tmp_link; |
36553434 | 825 | |
69d0206c TH |
826 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
827 | list_del(&link->cset_link); | |
36553434 LZ |
828 | kfree(link); |
829 | } | |
830 | } | |
831 | ||
69d0206c TH |
832 | /** |
833 | * allocate_cgrp_cset_links - allocate cgrp_cset_links | |
834 | * @count: the number of links to allocate | |
835 | * @tmp_links: list_head the allocated links are put on | |
836 | * | |
837 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links | |
838 | * through ->cset_link. Returns 0 on success or -errno. | |
817929ec | 839 | */ |
69d0206c | 840 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
817929ec | 841 | { |
69d0206c | 842 | struct cgrp_cset_link *link; |
817929ec | 843 | int i; |
69d0206c TH |
844 | |
845 | INIT_LIST_HEAD(tmp_links); | |
846 | ||
817929ec | 847 | for (i = 0; i < count; i++) { |
f4f4be2b | 848 | link = kzalloc(sizeof(*link), GFP_KERNEL); |
817929ec | 849 | if (!link) { |
69d0206c | 850 | free_cgrp_cset_links(tmp_links); |
817929ec PM |
851 | return -ENOMEM; |
852 | } | |
69d0206c | 853 | list_add(&link->cset_link, tmp_links); |
817929ec PM |
854 | } |
855 | return 0; | |
856 | } | |
857 | ||
c12f65d4 LZ |
858 | /** |
859 | * link_css_set - a helper function to link a css_set to a cgroup | |
69d0206c | 860 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
5abb8855 | 861 | * @cset: the css_set to be linked |
c12f65d4 LZ |
862 | * @cgrp: the destination cgroup |
863 | */ | |
69d0206c TH |
864 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
865 | struct cgroup *cgrp) | |
c12f65d4 | 866 | { |
69d0206c | 867 | struct cgrp_cset_link *link; |
c12f65d4 | 868 | |
69d0206c | 869 | BUG_ON(list_empty(tmp_links)); |
6803c006 TH |
870 | |
871 | if (cgroup_on_dfl(cgrp)) | |
872 | cset->dfl_cgrp = cgrp; | |
873 | ||
69d0206c TH |
874 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); |
875 | link->cset = cset; | |
7717f7ba | 876 | link->cgrp = cgrp; |
842b597e TH |
877 | |
878 | if (list_empty(&cgrp->cset_links)) | |
879 | cgroup_update_populated(cgrp, true); | |
69d0206c | 880 | list_move(&link->cset_link, &cgrp->cset_links); |
842b597e | 881 | |
7717f7ba PM |
882 | /* |
883 | * Always add links to the tail of the list so that the list | |
884 | * is sorted by order of hierarchy creation | |
885 | */ | |
69d0206c | 886 | list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
c12f65d4 LZ |
887 | } |
888 | ||
b326f9d0 TH |
889 | /** |
890 | * find_css_set - return a new css_set with one cgroup updated | |
891 | * @old_cset: the baseline css_set | |
892 | * @cgrp: the cgroup to be updated | |
893 | * | |
894 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp | |
895 | * substituted into the appropriate hierarchy. | |
817929ec | 896 | */ |
5abb8855 TH |
897 | static struct css_set *find_css_set(struct css_set *old_cset, |
898 | struct cgroup *cgrp) | |
817929ec | 899 | { |
b326f9d0 | 900 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
5abb8855 | 901 | struct css_set *cset; |
69d0206c TH |
902 | struct list_head tmp_links; |
903 | struct cgrp_cset_link *link; | |
2d8f243a | 904 | struct cgroup_subsys *ss; |
0ac801fe | 905 | unsigned long key; |
2d8f243a | 906 | int ssid; |
472b1053 | 907 | |
b326f9d0 TH |
908 | lockdep_assert_held(&cgroup_mutex); |
909 | ||
817929ec PM |
910 | /* First see if we already have a cgroup group that matches |
911 | * the desired set */ | |
96d365e0 | 912 | down_read(&css_set_rwsem); |
5abb8855 TH |
913 | cset = find_existing_css_set(old_cset, cgrp, template); |
914 | if (cset) | |
915 | get_css_set(cset); | |
96d365e0 | 916 | up_read(&css_set_rwsem); |
817929ec | 917 | |
5abb8855 TH |
918 | if (cset) |
919 | return cset; | |
817929ec | 920 | |
f4f4be2b | 921 | cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
5abb8855 | 922 | if (!cset) |
817929ec PM |
923 | return NULL; |
924 | ||
69d0206c | 925 | /* Allocate all the cgrp_cset_link objects that we'll need */ |
9871bf95 | 926 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
5abb8855 | 927 | kfree(cset); |
817929ec PM |
928 | return NULL; |
929 | } | |
930 | ||
5abb8855 | 931 | atomic_set(&cset->refcount, 1); |
69d0206c | 932 | INIT_LIST_HEAD(&cset->cgrp_links); |
5abb8855 | 933 | INIT_LIST_HEAD(&cset->tasks); |
c7561128 | 934 | INIT_LIST_HEAD(&cset->mg_tasks); |
1958d2d5 | 935 | INIT_LIST_HEAD(&cset->mg_preload_node); |
b3dc094e | 936 | INIT_LIST_HEAD(&cset->mg_node); |
5abb8855 | 937 | INIT_HLIST_NODE(&cset->hlist); |
817929ec PM |
938 | |
939 | /* Copy the set of subsystem state objects generated in | |
940 | * find_existing_css_set() */ | |
5abb8855 | 941 | memcpy(cset->subsys, template, sizeof(cset->subsys)); |
817929ec | 942 | |
96d365e0 | 943 | down_write(&css_set_rwsem); |
817929ec | 944 | /* Add reference counts and links from the new css_set. */ |
69d0206c | 945 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
7717f7ba | 946 | struct cgroup *c = link->cgrp; |
69d0206c | 947 | |
7717f7ba PM |
948 | if (c->root == cgrp->root) |
949 | c = cgrp; | |
69d0206c | 950 | link_css_set(&tmp_links, cset, c); |
7717f7ba | 951 | } |
817929ec | 952 | |
69d0206c | 953 | BUG_ON(!list_empty(&tmp_links)); |
817929ec | 954 | |
817929ec | 955 | css_set_count++; |
472b1053 | 956 | |
2d8f243a | 957 | /* Add @cset to the hash table */ |
5abb8855 TH |
958 | key = css_set_hash(cset->subsys); |
959 | hash_add(css_set_table, &cset->hlist, key); | |
472b1053 | 960 | |
2d8f243a TH |
961 | for_each_subsys(ss, ssid) |
962 | list_add_tail(&cset->e_cset_node[ssid], | |
963 | &cset->subsys[ssid]->cgroup->e_csets[ssid]); | |
964 | ||
96d365e0 | 965 | up_write(&css_set_rwsem); |
817929ec | 966 | |
5abb8855 | 967 | return cset; |
b4f48b63 PM |
968 | } |
969 | ||
3dd06ffa | 970 | static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
7717f7ba | 971 | { |
3dd06ffa | 972 | struct cgroup *root_cgrp = kf_root->kn->priv; |
2bd59d48 | 973 | |
3dd06ffa | 974 | return root_cgrp->root; |
2bd59d48 TH |
975 | } |
976 | ||
3dd06ffa | 977 | static int cgroup_init_root_id(struct cgroup_root *root) |
f2e85d57 TH |
978 | { |
979 | int id; | |
980 | ||
981 | lockdep_assert_held(&cgroup_mutex); | |
982 | ||
985ed670 | 983 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL); |
f2e85d57 TH |
984 | if (id < 0) |
985 | return id; | |
986 | ||
987 | root->hierarchy_id = id; | |
988 | return 0; | |
989 | } | |
990 | ||
3dd06ffa | 991 | static void cgroup_exit_root_id(struct cgroup_root *root) |
f2e85d57 TH |
992 | { |
993 | lockdep_assert_held(&cgroup_mutex); | |
994 | ||
995 | if (root->hierarchy_id) { | |
996 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); | |
997 | root->hierarchy_id = 0; | |
998 | } | |
999 | } | |
1000 | ||
3dd06ffa | 1001 | static void cgroup_free_root(struct cgroup_root *root) |
f2e85d57 TH |
1002 | { |
1003 | if (root) { | |
d0f702e6 | 1004 | /* hierarchy ID should already have been released */ |
f2e85d57 TH |
1005 | WARN_ON_ONCE(root->hierarchy_id); |
1006 | ||
1007 | idr_destroy(&root->cgroup_idr); | |
1008 | kfree(root); | |
1009 | } | |
1010 | } | |
1011 | ||
3dd06ffa | 1012 | static void cgroup_destroy_root(struct cgroup_root *root) |
59f5296b | 1013 | { |
3dd06ffa | 1014 | struct cgroup *cgrp = &root->cgrp; |
f2e85d57 | 1015 | struct cgrp_cset_link *link, *tmp_link; |
f2e85d57 | 1016 | |
2bd59d48 | 1017 | mutex_lock(&cgroup_mutex); |
f2e85d57 | 1018 | |
776f02fa | 1019 | BUG_ON(atomic_read(&root->nr_cgrps)); |
d5c419b6 | 1020 | BUG_ON(!list_empty(&cgrp->self.children)); |
f2e85d57 | 1021 | |
f2e85d57 | 1022 | /* Rebind all subsystems back to the default hierarchy */ |
f392e51c | 1023 | rebind_subsystems(&cgrp_dfl_root, root->subsys_mask); |
7717f7ba | 1024 | |
7717f7ba | 1025 | /* |
f2e85d57 TH |
1026 | * Release all the links from cset_links to this hierarchy's |
1027 | * root cgroup | |
7717f7ba | 1028 | */ |
96d365e0 | 1029 | down_write(&css_set_rwsem); |
f2e85d57 TH |
1030 | |
1031 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { | |
1032 | list_del(&link->cset_link); | |
1033 | list_del(&link->cgrp_link); | |
1034 | kfree(link); | |
1035 | } | |
96d365e0 | 1036 | up_write(&css_set_rwsem); |
f2e85d57 TH |
1037 | |
1038 | if (!list_empty(&root->root_list)) { | |
1039 | list_del(&root->root_list); | |
1040 | cgroup_root_count--; | |
1041 | } | |
1042 | ||
1043 | cgroup_exit_root_id(root); | |
1044 | ||
1045 | mutex_unlock(&cgroup_mutex); | |
f2e85d57 | 1046 | |
2bd59d48 | 1047 | kernfs_destroy_root(root->kf_root); |
f2e85d57 TH |
1048 | cgroup_free_root(root); |
1049 | } | |
1050 | ||
ceb6a081 TH |
1051 | /* look up cgroup associated with given css_set on the specified hierarchy */ |
1052 | static struct cgroup *cset_cgroup_from_root(struct css_set *cset, | |
3dd06ffa | 1053 | struct cgroup_root *root) |
7717f7ba | 1054 | { |
7717f7ba PM |
1055 | struct cgroup *res = NULL; |
1056 | ||
96d365e0 TH |
1057 | lockdep_assert_held(&cgroup_mutex); |
1058 | lockdep_assert_held(&css_set_rwsem); | |
1059 | ||
5abb8855 | 1060 | if (cset == &init_css_set) { |
3dd06ffa | 1061 | res = &root->cgrp; |
7717f7ba | 1062 | } else { |
69d0206c TH |
1063 | struct cgrp_cset_link *link; |
1064 | ||
1065 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { | |
7717f7ba | 1066 | struct cgroup *c = link->cgrp; |
69d0206c | 1067 | |
7717f7ba PM |
1068 | if (c->root == root) { |
1069 | res = c; | |
1070 | break; | |
1071 | } | |
1072 | } | |
1073 | } | |
96d365e0 | 1074 | |
7717f7ba PM |
1075 | BUG_ON(!res); |
1076 | return res; | |
1077 | } | |
1078 | ||
ddbcc7e8 | 1079 | /* |
ceb6a081 TH |
1080 | * Return the cgroup for "task" from the given hierarchy. Must be |
1081 | * called with cgroup_mutex and css_set_rwsem held. | |
1082 | */ | |
1083 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
3dd06ffa | 1084 | struct cgroup_root *root) |
ceb6a081 TH |
1085 | { |
1086 | /* | |
1087 | * No need to lock the task - since we hold cgroup_mutex the | |
1088 | * task can't change groups, so the only thing that can happen | |
1089 | * is that it exits and its css is set back to init_css_set. | |
1090 | */ | |
1091 | return cset_cgroup_from_root(task_css_set(task), root); | |
1092 | } | |
1093 | ||
ddbcc7e8 | 1094 | /* |
ddbcc7e8 PM |
1095 | * A task must hold cgroup_mutex to modify cgroups. |
1096 | * | |
1097 | * Any task can increment and decrement the count field without lock. | |
1098 | * So in general, code holding cgroup_mutex can't rely on the count | |
1099 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 1100 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
1101 | * means that no tasks are currently attached, therefore there is no |
1102 | * way a task attached to that cgroup can fork (the other way to | |
1103 | * increment the count). So code holding cgroup_mutex can safely | |
1104 | * assume that if the count is zero, it will stay zero. Similarly, if | |
1105 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
1106 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
1107 | * needs that mutex. | |
1108 | * | |
ddbcc7e8 PM |
1109 | * A cgroup can only be deleted if both its 'count' of using tasks |
1110 | * is zero, and its list of 'children' cgroups is empty. Since all | |
1111 | * tasks in the system use _some_ cgroup, and since there is always at | |
3dd06ffa | 1112 | * least one task in the system (init, pid == 1), therefore, root cgroup |
ddbcc7e8 | 1113 | * always has either children cgroups and/or using tasks. So we don't |
3dd06ffa | 1114 | * need a special hack to ensure that root cgroup cannot be deleted. |
ddbcc7e8 PM |
1115 | * |
1116 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 1117 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
1118 | */ |
1119 | ||
2bd59d48 | 1120 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
828c0950 | 1121 | static const struct file_operations proc_cgroupstats_operations; |
a424316c | 1122 | |
8d7e6fb0 TH |
1123 | static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
1124 | char *buf) | |
ddbcc7e8 | 1125 | { |
3e1d2eed TH |
1126 | struct cgroup_subsys *ss = cft->ss; |
1127 | ||
8d7e6fb0 TH |
1128 | if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && |
1129 | !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) | |
1130 | snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s", | |
3e1d2eed TH |
1131 | cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name, |
1132 | cft->name); | |
8d7e6fb0 TH |
1133 | else |
1134 | strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX); | |
1135 | return buf; | |
ddbcc7e8 PM |
1136 | } |
1137 | ||
f2e85d57 TH |
1138 | /** |
1139 | * cgroup_file_mode - deduce file mode of a control file | |
1140 | * @cft: the control file in question | |
1141 | * | |
7dbdb199 | 1142 | * S_IRUGO for read, S_IWUSR for write. |
f2e85d57 TH |
1143 | */ |
1144 | static umode_t cgroup_file_mode(const struct cftype *cft) | |
65dff759 | 1145 | { |
f2e85d57 | 1146 | umode_t mode = 0; |
65dff759 | 1147 | |
f2e85d57 TH |
1148 | if (cft->read_u64 || cft->read_s64 || cft->seq_show) |
1149 | mode |= S_IRUGO; | |
1150 | ||
7dbdb199 TH |
1151 | if (cft->write_u64 || cft->write_s64 || cft->write) { |
1152 | if (cft->flags & CFTYPE_WORLD_WRITABLE) | |
1153 | mode |= S_IWUGO; | |
1154 | else | |
1155 | mode |= S_IWUSR; | |
1156 | } | |
f2e85d57 TH |
1157 | |
1158 | return mode; | |
65dff759 LZ |
1159 | } |
1160 | ||
59f5296b | 1161 | static void cgroup_get(struct cgroup *cgrp) |
be445626 | 1162 | { |
2bd59d48 | 1163 | WARN_ON_ONCE(cgroup_is_dead(cgrp)); |
9d755d33 | 1164 | css_get(&cgrp->self); |
be445626 LZ |
1165 | } |
1166 | ||
aa32362f LZ |
1167 | static bool cgroup_tryget(struct cgroup *cgrp) |
1168 | { | |
1169 | return css_tryget(&cgrp->self); | |
1170 | } | |
1171 | ||
59f5296b | 1172 | static void cgroup_put(struct cgroup *cgrp) |
be445626 | 1173 | { |
9d755d33 | 1174 | css_put(&cgrp->self); |
be445626 LZ |
1175 | } |
1176 | ||
af0ba678 | 1177 | /** |
0f060deb | 1178 | * cgroup_calc_child_subsys_mask - calculate child_subsys_mask |
af0ba678 | 1179 | * @cgrp: the target cgroup |
0f060deb | 1180 | * @subtree_control: the new subtree_control mask to consider |
af0ba678 TH |
1181 | * |
1182 | * On the default hierarchy, a subsystem may request other subsystems to be | |
1183 | * enabled together through its ->depends_on mask. In such cases, more | |
1184 | * subsystems than specified in "cgroup.subtree_control" may be enabled. | |
1185 | * | |
0f060deb TH |
1186 | * This function calculates which subsystems need to be enabled if |
1187 | * @subtree_control is to be applied to @cgrp. The returned mask is always | |
1188 | * a superset of @subtree_control and follows the usual hierarchy rules. | |
af0ba678 | 1189 | */ |
8ab456ac AS |
1190 | static unsigned long cgroup_calc_child_subsys_mask(struct cgroup *cgrp, |
1191 | unsigned long subtree_control) | |
667c2491 | 1192 | { |
af0ba678 | 1193 | struct cgroup *parent = cgroup_parent(cgrp); |
8ab456ac | 1194 | unsigned long cur_ss_mask = subtree_control; |
af0ba678 TH |
1195 | struct cgroup_subsys *ss; |
1196 | int ssid; | |
1197 | ||
1198 | lockdep_assert_held(&cgroup_mutex); | |
1199 | ||
0f060deb TH |
1200 | if (!cgroup_on_dfl(cgrp)) |
1201 | return cur_ss_mask; | |
af0ba678 TH |
1202 | |
1203 | while (true) { | |
8ab456ac | 1204 | unsigned long new_ss_mask = cur_ss_mask; |
af0ba678 | 1205 | |
a966a4ed AS |
1206 | for_each_subsys_which(ss, ssid, &cur_ss_mask) |
1207 | new_ss_mask |= ss->depends_on; | |
af0ba678 TH |
1208 | |
1209 | /* | |
1210 | * Mask out subsystems which aren't available. This can | |
1211 | * happen only if some depended-upon subsystems were bound | |
1212 | * to non-default hierarchies. | |
1213 | */ | |
1214 | if (parent) | |
1215 | new_ss_mask &= parent->child_subsys_mask; | |
1216 | else | |
1217 | new_ss_mask &= cgrp->root->subsys_mask; | |
1218 | ||
1219 | if (new_ss_mask == cur_ss_mask) | |
1220 | break; | |
1221 | cur_ss_mask = new_ss_mask; | |
1222 | } | |
1223 | ||
0f060deb TH |
1224 | return cur_ss_mask; |
1225 | } | |
1226 | ||
1227 | /** | |
1228 | * cgroup_refresh_child_subsys_mask - update child_subsys_mask | |
1229 | * @cgrp: the target cgroup | |
1230 | * | |
1231 | * Update @cgrp->child_subsys_mask according to the current | |
1232 | * @cgrp->subtree_control using cgroup_calc_child_subsys_mask(). | |
1233 | */ | |
1234 | static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp) | |
1235 | { | |
1236 | cgrp->child_subsys_mask = | |
1237 | cgroup_calc_child_subsys_mask(cgrp, cgrp->subtree_control); | |
667c2491 TH |
1238 | } |
1239 | ||
a9746d8d TH |
1240 | /** |
1241 | * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods | |
1242 | * @kn: the kernfs_node being serviced | |
1243 | * | |
1244 | * This helper undoes cgroup_kn_lock_live() and should be invoked before | |
1245 | * the method finishes if locking succeeded. Note that once this function | |
1246 | * returns the cgroup returned by cgroup_kn_lock_live() may become | |
1247 | * inaccessible any time. If the caller intends to continue to access the | |
1248 | * cgroup, it should pin it before invoking this function. | |
1249 | */ | |
1250 | static void cgroup_kn_unlock(struct kernfs_node *kn) | |
ddbcc7e8 | 1251 | { |
a9746d8d TH |
1252 | struct cgroup *cgrp; |
1253 | ||
1254 | if (kernfs_type(kn) == KERNFS_DIR) | |
1255 | cgrp = kn->priv; | |
1256 | else | |
1257 | cgrp = kn->parent->priv; | |
1258 | ||
1259 | mutex_unlock(&cgroup_mutex); | |
a9746d8d TH |
1260 | |
1261 | kernfs_unbreak_active_protection(kn); | |
1262 | cgroup_put(cgrp); | |
ddbcc7e8 PM |
1263 | } |
1264 | ||
a9746d8d TH |
1265 | /** |
1266 | * cgroup_kn_lock_live - locking helper for cgroup kernfs methods | |
1267 | * @kn: the kernfs_node being serviced | |
1268 | * | |
1269 | * This helper is to be used by a cgroup kernfs method currently servicing | |
1270 | * @kn. It breaks the active protection, performs cgroup locking and | |
1271 | * verifies that the associated cgroup is alive. Returns the cgroup if | |
1272 | * alive; otherwise, %NULL. A successful return should be undone by a | |
1273 | * matching cgroup_kn_unlock() invocation. | |
1274 | * | |
1275 | * Any cgroup kernfs method implementation which requires locking the | |
1276 | * associated cgroup should use this helper. It avoids nesting cgroup | |
1277 | * locking under kernfs active protection and allows all kernfs operations | |
1278 | * including self-removal. | |
1279 | */ | |
1280 | static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn) | |
05ef1d7c | 1281 | { |
a9746d8d TH |
1282 | struct cgroup *cgrp; |
1283 | ||
1284 | if (kernfs_type(kn) == KERNFS_DIR) | |
1285 | cgrp = kn->priv; | |
1286 | else | |
1287 | cgrp = kn->parent->priv; | |
05ef1d7c | 1288 | |
2739d3cc | 1289 | /* |
01f6474c | 1290 | * We're gonna grab cgroup_mutex which nests outside kernfs |
a9746d8d TH |
1291 | * active_ref. cgroup liveliness check alone provides enough |
1292 | * protection against removal. Ensure @cgrp stays accessible and | |
1293 | * break the active_ref protection. | |
2739d3cc | 1294 | */ |
aa32362f LZ |
1295 | if (!cgroup_tryget(cgrp)) |
1296 | return NULL; | |
a9746d8d TH |
1297 | kernfs_break_active_protection(kn); |
1298 | ||
2bd59d48 | 1299 | mutex_lock(&cgroup_mutex); |
05ef1d7c | 1300 | |
a9746d8d TH |
1301 | if (!cgroup_is_dead(cgrp)) |
1302 | return cgrp; | |
1303 | ||
1304 | cgroup_kn_unlock(kn); | |
1305 | return NULL; | |
ddbcc7e8 | 1306 | } |
05ef1d7c | 1307 | |
2739d3cc | 1308 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c | 1309 | { |
2bd59d48 | 1310 | char name[CGROUP_FILE_NAME_MAX]; |
05ef1d7c | 1311 | |
01f6474c | 1312 | lockdep_assert_held(&cgroup_mutex); |
2bd59d48 | 1313 | kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
05ef1d7c TH |
1314 | } |
1315 | ||
13af07df | 1316 | /** |
4df8dc90 TH |
1317 | * css_clear_dir - remove subsys files in a cgroup directory |
1318 | * @css: taget css | |
1319 | * @cgrp_override: specify if target cgroup is different from css->cgroup | |
13af07df | 1320 | */ |
4df8dc90 TH |
1321 | static void css_clear_dir(struct cgroup_subsys_state *css, |
1322 | struct cgroup *cgrp_override) | |
05ef1d7c | 1323 | { |
4df8dc90 TH |
1324 | struct cgroup *cgrp = cgrp_override ?: css->cgroup; |
1325 | struct cftype *cfts; | |
05ef1d7c | 1326 | |
4df8dc90 TH |
1327 | list_for_each_entry(cfts, &css->ss->cfts, node) |
1328 | cgroup_addrm_files(css, cgrp, cfts, false); | |
ddbcc7e8 PM |
1329 | } |
1330 | ||
ccdca218 | 1331 | /** |
4df8dc90 TH |
1332 | * css_populate_dir - create subsys files in a cgroup directory |
1333 | * @css: target css | |
1334 | * @cgrp_overried: specify if target cgroup is different from css->cgroup | |
ccdca218 TH |
1335 | * |
1336 | * On failure, no file is added. | |
1337 | */ | |
4df8dc90 TH |
1338 | static int css_populate_dir(struct cgroup_subsys_state *css, |
1339 | struct cgroup *cgrp_override) | |
ccdca218 | 1340 | { |
4df8dc90 TH |
1341 | struct cgroup *cgrp = cgrp_override ?: css->cgroup; |
1342 | struct cftype *cfts, *failed_cfts; | |
1343 | int ret; | |
ccdca218 | 1344 | |
4df8dc90 TH |
1345 | if (!css->ss) { |
1346 | if (cgroup_on_dfl(cgrp)) | |
1347 | cfts = cgroup_dfl_base_files; | |
1348 | else | |
1349 | cfts = cgroup_legacy_base_files; | |
ccdca218 | 1350 | |
4df8dc90 TH |
1351 | return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true); |
1352 | } | |
ccdca218 | 1353 | |
4df8dc90 TH |
1354 | list_for_each_entry(cfts, &css->ss->cfts, node) { |
1355 | ret = cgroup_addrm_files(css, cgrp, cfts, true); | |
1356 | if (ret < 0) { | |
1357 | failed_cfts = cfts; | |
1358 | goto err; | |
ccdca218 TH |
1359 | } |
1360 | } | |
1361 | return 0; | |
1362 | err: | |
4df8dc90 TH |
1363 | list_for_each_entry(cfts, &css->ss->cfts, node) { |
1364 | if (cfts == failed_cfts) | |
1365 | break; | |
1366 | cgroup_addrm_files(css, cgrp, cfts, false); | |
1367 | } | |
ccdca218 TH |
1368 | return ret; |
1369 | } | |
1370 | ||
8ab456ac AS |
1371 | static int rebind_subsystems(struct cgroup_root *dst_root, |
1372 | unsigned long ss_mask) | |
ddbcc7e8 | 1373 | { |
1ada4838 | 1374 | struct cgroup *dcgrp = &dst_root->cgrp; |
30159ec7 | 1375 | struct cgroup_subsys *ss; |
8ab456ac | 1376 | unsigned long tmp_ss_mask; |
2d8f243a | 1377 | int ssid, i, ret; |
ddbcc7e8 | 1378 | |
ace2bee8 | 1379 | lockdep_assert_held(&cgroup_mutex); |
ddbcc7e8 | 1380 | |
a966a4ed | 1381 | for_each_subsys_which(ss, ssid, &ss_mask) { |
7fd8c565 TH |
1382 | /* if @ss has non-root csses attached to it, can't move */ |
1383 | if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss))) | |
3ed80a62 | 1384 | return -EBUSY; |
1d5be6b2 | 1385 | |
5df36032 | 1386 | /* can't move between two non-dummy roots either */ |
7fd8c565 | 1387 | if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root) |
5df36032 | 1388 | return -EBUSY; |
ddbcc7e8 PM |
1389 | } |
1390 | ||
5533e011 TH |
1391 | /* skip creating root files on dfl_root for inhibited subsystems */ |
1392 | tmp_ss_mask = ss_mask; | |
1393 | if (dst_root == &cgrp_dfl_root) | |
1394 | tmp_ss_mask &= ~cgrp_dfl_root_inhibit_ss_mask; | |
1395 | ||
4df8dc90 TH |
1396 | for_each_subsys_which(ss, ssid, &tmp_ss_mask) { |
1397 | struct cgroup *scgrp = &ss->root->cgrp; | |
1398 | int tssid; | |
1399 | ||
1400 | ret = css_populate_dir(cgroup_css(scgrp, ss), dcgrp); | |
1401 | if (!ret) | |
1402 | continue; | |
ddbcc7e8 | 1403 | |
a2dd4247 TH |
1404 | /* |
1405 | * Rebinding back to the default root is not allowed to | |
1406 | * fail. Using both default and non-default roots should | |
1407 | * be rare. Moving subsystems back and forth even more so. | |
1408 | * Just warn about it and continue. | |
1409 | */ | |
4df8dc90 TH |
1410 | if (dst_root == &cgrp_dfl_root) { |
1411 | if (cgrp_dfl_root_visible) { | |
1412 | pr_warn("failed to create files (%d) while rebinding 0x%lx to default root\n", | |
1413 | ret, ss_mask); | |
1414 | pr_warn("you may retry by moving them to a different hierarchy and unbinding\n"); | |
1415 | } | |
1416 | continue; | |
a2dd4247 | 1417 | } |
4df8dc90 TH |
1418 | |
1419 | for_each_subsys_which(ss, tssid, &tmp_ss_mask) { | |
1420 | if (tssid == ssid) | |
1421 | break; | |
1422 | css_clear_dir(cgroup_css(scgrp, ss), dcgrp); | |
1423 | } | |
1424 | return ret; | |
5df36032 | 1425 | } |
3126121f TH |
1426 | |
1427 | /* | |
1428 | * Nothing can fail from this point on. Remove files for the | |
1429 | * removed subsystems and rebind each subsystem. | |
1430 | */ | |
a966a4ed | 1431 | for_each_subsys_which(ss, ssid, &ss_mask) { |
1ada4838 TH |
1432 | struct cgroup_root *src_root = ss->root; |
1433 | struct cgroup *scgrp = &src_root->cgrp; | |
1434 | struct cgroup_subsys_state *css = cgroup_css(scgrp, ss); | |
2d8f243a | 1435 | struct css_set *cset; |
a8a648c4 | 1436 | |
1ada4838 | 1437 | WARN_ON(!css || cgroup_css(dcgrp, ss)); |
a8a648c4 | 1438 | |
4df8dc90 TH |
1439 | css_clear_dir(css, NULL); |
1440 | ||
1ada4838 TH |
1441 | RCU_INIT_POINTER(scgrp->subsys[ssid], NULL); |
1442 | rcu_assign_pointer(dcgrp->subsys[ssid], css); | |
5df36032 | 1443 | ss->root = dst_root; |
1ada4838 | 1444 | css->cgroup = dcgrp; |
73e80ed8 | 1445 | |
2d8f243a TH |
1446 | down_write(&css_set_rwsem); |
1447 | hash_for_each(css_set_table, i, cset, hlist) | |
1448 | list_move_tail(&cset->e_cset_node[ss->id], | |
1ada4838 | 1449 | &dcgrp->e_csets[ss->id]); |
2d8f243a TH |
1450 | up_write(&css_set_rwsem); |
1451 | ||
f392e51c | 1452 | src_root->subsys_mask &= ~(1 << ssid); |
1ada4838 TH |
1453 | scgrp->subtree_control &= ~(1 << ssid); |
1454 | cgroup_refresh_child_subsys_mask(scgrp); | |
f392e51c | 1455 | |
bd53d617 | 1456 | /* default hierarchy doesn't enable controllers by default */ |
f392e51c | 1457 | dst_root->subsys_mask |= 1 << ssid; |
49d1dc4b TH |
1458 | if (dst_root == &cgrp_dfl_root) { |
1459 | static_branch_enable(cgroup_subsys_on_dfl_key[ssid]); | |
1460 | } else { | |
1ada4838 TH |
1461 | dcgrp->subtree_control |= 1 << ssid; |
1462 | cgroup_refresh_child_subsys_mask(dcgrp); | |
49d1dc4b | 1463 | static_branch_disable(cgroup_subsys_on_dfl_key[ssid]); |
667c2491 | 1464 | } |
a8a648c4 | 1465 | |
5df36032 TH |
1466 | if (ss->bind) |
1467 | ss->bind(css); | |
ddbcc7e8 | 1468 | } |
ddbcc7e8 | 1469 | |
1ada4838 | 1470 | kernfs_activate(dcgrp->kn); |
ddbcc7e8 PM |
1471 | return 0; |
1472 | } | |
1473 | ||
2bd59d48 TH |
1474 | static int cgroup_show_options(struct seq_file *seq, |
1475 | struct kernfs_root *kf_root) | |
ddbcc7e8 | 1476 | { |
3dd06ffa | 1477 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1478 | struct cgroup_subsys *ss; |
b85d2040 | 1479 | int ssid; |
ddbcc7e8 | 1480 | |
d98817d4 TH |
1481 | if (root != &cgrp_dfl_root) |
1482 | for_each_subsys(ss, ssid) | |
1483 | if (root->subsys_mask & (1 << ssid)) | |
61e57c0c | 1484 | seq_show_option(seq, ss->legacy_name, NULL); |
93438629 | 1485 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1486 | seq_puts(seq, ",noprefix"); |
93438629 | 1487 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1488 | seq_puts(seq, ",xattr"); |
69e943b7 TH |
1489 | |
1490 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1491 | if (strlen(root->release_agent_path)) |
a068acf2 KC |
1492 | seq_show_option(seq, "release_agent", |
1493 | root->release_agent_path); | |
69e943b7 TH |
1494 | spin_unlock(&release_agent_path_lock); |
1495 | ||
3dd06ffa | 1496 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags)) |
97978e6d | 1497 | seq_puts(seq, ",clone_children"); |
c6d57f33 | 1498 | if (strlen(root->name)) |
a068acf2 | 1499 | seq_show_option(seq, "name", root->name); |
ddbcc7e8 PM |
1500 | return 0; |
1501 | } | |
1502 | ||
1503 | struct cgroup_sb_opts { | |
8ab456ac | 1504 | unsigned long subsys_mask; |
69dfa00c | 1505 | unsigned int flags; |
81a6a5cd | 1506 | char *release_agent; |
2260e7fc | 1507 | bool cpuset_clone_children; |
c6d57f33 | 1508 | char *name; |
2c6ab6d2 PM |
1509 | /* User explicitly requested empty subsystem */ |
1510 | bool none; | |
ddbcc7e8 PM |
1511 | }; |
1512 | ||
cf5d5941 | 1513 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1514 | { |
32a8cf23 DL |
1515 | char *token, *o = data; |
1516 | bool all_ss = false, one_ss = false; | |
8ab456ac | 1517 | unsigned long mask = -1UL; |
30159ec7 | 1518 | struct cgroup_subsys *ss; |
7b9a6ba5 | 1519 | int nr_opts = 0; |
30159ec7 | 1520 | int i; |
f9ab5b5b LZ |
1521 | |
1522 | #ifdef CONFIG_CPUSETS | |
69dfa00c | 1523 | mask = ~(1U << cpuset_cgrp_id); |
f9ab5b5b | 1524 | #endif |
ddbcc7e8 | 1525 | |
c6d57f33 | 1526 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1527 | |
1528 | while ((token = strsep(&o, ",")) != NULL) { | |
7b9a6ba5 TH |
1529 | nr_opts++; |
1530 | ||
ddbcc7e8 PM |
1531 | if (!*token) |
1532 | return -EINVAL; | |
32a8cf23 | 1533 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1534 | /* Explicitly have no subsystems */ |
1535 | opts->none = true; | |
32a8cf23 DL |
1536 | continue; |
1537 | } | |
1538 | if (!strcmp(token, "all")) { | |
1539 | /* Mutually exclusive option 'all' + subsystem name */ | |
1540 | if (one_ss) | |
1541 | return -EINVAL; | |
1542 | all_ss = true; | |
1543 | continue; | |
1544 | } | |
873fe09e TH |
1545 | if (!strcmp(token, "__DEVEL__sane_behavior")) { |
1546 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; | |
1547 | continue; | |
1548 | } | |
32a8cf23 | 1549 | if (!strcmp(token, "noprefix")) { |
93438629 | 1550 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1551 | continue; |
1552 | } | |
1553 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1554 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1555 | continue; |
1556 | } | |
03b1cde6 | 1557 | if (!strcmp(token, "xattr")) { |
93438629 | 1558 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1559 | continue; |
1560 | } | |
32a8cf23 | 1561 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1562 | /* Specifying two release agents is forbidden */ |
1563 | if (opts->release_agent) | |
1564 | return -EINVAL; | |
c6d57f33 | 1565 | opts->release_agent = |
e400c285 | 1566 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1567 | if (!opts->release_agent) |
1568 | return -ENOMEM; | |
32a8cf23 DL |
1569 | continue; |
1570 | } | |
1571 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1572 | const char *name = token + 5; |
1573 | /* Can't specify an empty name */ | |
1574 | if (!strlen(name)) | |
1575 | return -EINVAL; | |
1576 | /* Must match [\w.-]+ */ | |
1577 | for (i = 0; i < strlen(name); i++) { | |
1578 | char c = name[i]; | |
1579 | if (isalnum(c)) | |
1580 | continue; | |
1581 | if ((c == '.') || (c == '-') || (c == '_')) | |
1582 | continue; | |
1583 | return -EINVAL; | |
1584 | } | |
1585 | /* Specifying two names is forbidden */ | |
1586 | if (opts->name) | |
1587 | return -EINVAL; | |
1588 | opts->name = kstrndup(name, | |
e400c285 | 1589 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1590 | GFP_KERNEL); |
1591 | if (!opts->name) | |
1592 | return -ENOMEM; | |
32a8cf23 DL |
1593 | |
1594 | continue; | |
1595 | } | |
1596 | ||
30159ec7 | 1597 | for_each_subsys(ss, i) { |
3e1d2eed | 1598 | if (strcmp(token, ss->legacy_name)) |
32a8cf23 | 1599 | continue; |
fc5ed1e9 | 1600 | if (!cgroup_ssid_enabled(i)) |
32a8cf23 DL |
1601 | continue; |
1602 | ||
1603 | /* Mutually exclusive option 'all' + subsystem name */ | |
1604 | if (all_ss) | |
1605 | return -EINVAL; | |
69dfa00c | 1606 | opts->subsys_mask |= (1 << i); |
32a8cf23 DL |
1607 | one_ss = true; |
1608 | ||
1609 | break; | |
1610 | } | |
1611 | if (i == CGROUP_SUBSYS_COUNT) | |
1612 | return -ENOENT; | |
1613 | } | |
1614 | ||
873fe09e | 1615 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
ed3d261b | 1616 | pr_warn("sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); |
7b9a6ba5 TH |
1617 | if (nr_opts != 1) { |
1618 | pr_err("sane_behavior: no other mount options allowed\n"); | |
873fe09e TH |
1619 | return -EINVAL; |
1620 | } | |
7b9a6ba5 | 1621 | return 0; |
873fe09e TH |
1622 | } |
1623 | ||
7b9a6ba5 TH |
1624 | /* |
1625 | * If the 'all' option was specified select all the subsystems, | |
1626 | * otherwise if 'none', 'name=' and a subsystem name options were | |
1627 | * not specified, let's default to 'all' | |
1628 | */ | |
1629 | if (all_ss || (!one_ss && !opts->none && !opts->name)) | |
1630 | for_each_subsys(ss, i) | |
fc5ed1e9 | 1631 | if (cgroup_ssid_enabled(i)) |
7b9a6ba5 TH |
1632 | opts->subsys_mask |= (1 << i); |
1633 | ||
1634 | /* | |
1635 | * We either have to specify by name or by subsystems. (So all | |
1636 | * empty hierarchies must have a name). | |
1637 | */ | |
1638 | if (!opts->subsys_mask && !opts->name) | |
1639 | return -EINVAL; | |
1640 | ||
f9ab5b5b LZ |
1641 | /* |
1642 | * Option noprefix was introduced just for backward compatibility | |
1643 | * with the old cpuset, so we allow noprefix only if mounting just | |
1644 | * the cpuset subsystem. | |
1645 | */ | |
93438629 | 1646 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1647 | return -EINVAL; |
1648 | ||
2c6ab6d2 | 1649 | /* Can't specify "none" and some subsystems */ |
a1a71b45 | 1650 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1651 | return -EINVAL; |
1652 | ||
ddbcc7e8 PM |
1653 | return 0; |
1654 | } | |
1655 | ||
2bd59d48 | 1656 | static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) |
ddbcc7e8 PM |
1657 | { |
1658 | int ret = 0; | |
3dd06ffa | 1659 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1660 | struct cgroup_sb_opts opts; |
8ab456ac | 1661 | unsigned long added_mask, removed_mask; |
ddbcc7e8 | 1662 | |
aa6ec29b TH |
1663 | if (root == &cgrp_dfl_root) { |
1664 | pr_err("remount is not allowed\n"); | |
873fe09e TH |
1665 | return -EINVAL; |
1666 | } | |
1667 | ||
ddbcc7e8 PM |
1668 | mutex_lock(&cgroup_mutex); |
1669 | ||
1670 | /* See what subsystems are wanted */ | |
1671 | ret = parse_cgroupfs_options(data, &opts); | |
1672 | if (ret) | |
1673 | goto out_unlock; | |
1674 | ||
f392e51c | 1675 | if (opts.subsys_mask != root->subsys_mask || opts.release_agent) |
ed3d261b | 1676 | pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", |
a2a1f9ea | 1677 | task_tgid_nr(current), current->comm); |
8b5a5a9d | 1678 | |
f392e51c TH |
1679 | added_mask = opts.subsys_mask & ~root->subsys_mask; |
1680 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
13af07df | 1681 | |
cf5d5941 | 1682 | /* Don't allow flags or name to change at remount */ |
7450e90b | 1683 | if ((opts.flags ^ root->flags) || |
cf5d5941 | 1684 | (opts.name && strcmp(opts.name, root->name))) { |
69dfa00c | 1685 | pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n", |
7450e90b | 1686 | opts.flags, opts.name ?: "", root->flags, root->name); |
c6d57f33 PM |
1687 | ret = -EINVAL; |
1688 | goto out_unlock; | |
1689 | } | |
1690 | ||
f172e67c | 1691 | /* remounting is not allowed for populated hierarchies */ |
d5c419b6 | 1692 | if (!list_empty(&root->cgrp.self.children)) { |
f172e67c | 1693 | ret = -EBUSY; |
0670e08b | 1694 | goto out_unlock; |
cf5d5941 | 1695 | } |
ddbcc7e8 | 1696 | |
5df36032 | 1697 | ret = rebind_subsystems(root, added_mask); |
3126121f | 1698 | if (ret) |
0670e08b | 1699 | goto out_unlock; |
ddbcc7e8 | 1700 | |
3dd06ffa | 1701 | rebind_subsystems(&cgrp_dfl_root, removed_mask); |
5df36032 | 1702 | |
69e943b7 TH |
1703 | if (opts.release_agent) { |
1704 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1705 | strcpy(root->release_agent_path, opts.release_agent); |
69e943b7 TH |
1706 | spin_unlock(&release_agent_path_lock); |
1707 | } | |
ddbcc7e8 | 1708 | out_unlock: |
66bdc9cf | 1709 | kfree(opts.release_agent); |
c6d57f33 | 1710 | kfree(opts.name); |
ddbcc7e8 | 1711 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
1712 | return ret; |
1713 | } | |
1714 | ||
afeb0f9f TH |
1715 | /* |
1716 | * To reduce the fork() overhead for systems that are not actually using | |
1717 | * their cgroups capability, we don't maintain the lists running through | |
1718 | * each css_set to its tasks until we see the list actually used - in other | |
1719 | * words after the first mount. | |
1720 | */ | |
1721 | static bool use_task_css_set_links __read_mostly; | |
1722 | ||
1723 | static void cgroup_enable_task_cg_lists(void) | |
1724 | { | |
1725 | struct task_struct *p, *g; | |
1726 | ||
96d365e0 | 1727 | down_write(&css_set_rwsem); |
afeb0f9f TH |
1728 | |
1729 | if (use_task_css_set_links) | |
1730 | goto out_unlock; | |
1731 | ||
1732 | use_task_css_set_links = true; | |
1733 | ||
1734 | /* | |
1735 | * We need tasklist_lock because RCU is not safe against | |
1736 | * while_each_thread(). Besides, a forking task that has passed | |
1737 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
1738 | * is not guaranteed to have its child immediately visible in the | |
1739 | * tasklist if we walk through it with RCU. | |
1740 | */ | |
1741 | read_lock(&tasklist_lock); | |
1742 | do_each_thread(g, p) { | |
afeb0f9f TH |
1743 | WARN_ON_ONCE(!list_empty(&p->cg_list) || |
1744 | task_css_set(p) != &init_css_set); | |
1745 | ||
1746 | /* | |
1747 | * We should check if the process is exiting, otherwise | |
1748 | * it will race with cgroup_exit() in that the list | |
1749 | * entry won't be deleted though the process has exited. | |
f153ad11 TH |
1750 | * Do it while holding siglock so that we don't end up |
1751 | * racing against cgroup_exit(). | |
afeb0f9f | 1752 | */ |
f153ad11 | 1753 | spin_lock_irq(&p->sighand->siglock); |
eaf797ab TH |
1754 | if (!(p->flags & PF_EXITING)) { |
1755 | struct css_set *cset = task_css_set(p); | |
1756 | ||
1757 | list_add(&p->cg_list, &cset->tasks); | |
1758 | get_css_set(cset); | |
1759 | } | |
f153ad11 | 1760 | spin_unlock_irq(&p->sighand->siglock); |
afeb0f9f TH |
1761 | } while_each_thread(g, p); |
1762 | read_unlock(&tasklist_lock); | |
1763 | out_unlock: | |
96d365e0 | 1764 | up_write(&css_set_rwsem); |
afeb0f9f | 1765 | } |
ddbcc7e8 | 1766 | |
cc31edce PM |
1767 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1768 | { | |
2d8f243a TH |
1769 | struct cgroup_subsys *ss; |
1770 | int ssid; | |
1771 | ||
d5c419b6 TH |
1772 | INIT_LIST_HEAD(&cgrp->self.sibling); |
1773 | INIT_LIST_HEAD(&cgrp->self.children); | |
6f60eade | 1774 | INIT_LIST_HEAD(&cgrp->self.files); |
69d0206c | 1775 | INIT_LIST_HEAD(&cgrp->cset_links); |
72a8cb30 BB |
1776 | INIT_LIST_HEAD(&cgrp->pidlists); |
1777 | mutex_init(&cgrp->pidlist_mutex); | |
9d800df1 | 1778 | cgrp->self.cgroup = cgrp; |
184faf32 | 1779 | cgrp->self.flags |= CSS_ONLINE; |
2d8f243a TH |
1780 | |
1781 | for_each_subsys(ss, ssid) | |
1782 | INIT_LIST_HEAD(&cgrp->e_csets[ssid]); | |
f8f22e53 TH |
1783 | |
1784 | init_waitqueue_head(&cgrp->offline_waitq); | |
971ff493 | 1785 | INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent); |
cc31edce | 1786 | } |
c6d57f33 | 1787 | |
3dd06ffa | 1788 | static void init_cgroup_root(struct cgroup_root *root, |
172a2c06 | 1789 | struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1790 | { |
3dd06ffa | 1791 | struct cgroup *cgrp = &root->cgrp; |
b0ca5a84 | 1792 | |
ddbcc7e8 | 1793 | INIT_LIST_HEAD(&root->root_list); |
3c9c825b | 1794 | atomic_set(&root->nr_cgrps, 1); |
bd89aabc | 1795 | cgrp->root = root; |
cc31edce | 1796 | init_cgroup_housekeeping(cgrp); |
4e96ee8e | 1797 | idr_init(&root->cgroup_idr); |
c6d57f33 | 1798 | |
c6d57f33 PM |
1799 | root->flags = opts->flags; |
1800 | if (opts->release_agent) | |
1801 | strcpy(root->release_agent_path, opts->release_agent); | |
1802 | if (opts->name) | |
1803 | strcpy(root->name, opts->name); | |
2260e7fc | 1804 | if (opts->cpuset_clone_children) |
3dd06ffa | 1805 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
c6d57f33 PM |
1806 | } |
1807 | ||
8ab456ac | 1808 | static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) |
2c6ab6d2 | 1809 | { |
d427dfeb | 1810 | LIST_HEAD(tmp_links); |
3dd06ffa | 1811 | struct cgroup *root_cgrp = &root->cgrp; |
d427dfeb | 1812 | struct css_set *cset; |
d427dfeb | 1813 | int i, ret; |
2c6ab6d2 | 1814 | |
d427dfeb | 1815 | lockdep_assert_held(&cgroup_mutex); |
c6d57f33 | 1816 | |
cf780b7d | 1817 | ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL); |
d427dfeb | 1818 | if (ret < 0) |
2bd59d48 | 1819 | goto out; |
d427dfeb | 1820 | root_cgrp->id = ret; |
c6d57f33 | 1821 | |
2aad2a86 TH |
1822 | ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0, |
1823 | GFP_KERNEL); | |
9d755d33 TH |
1824 | if (ret) |
1825 | goto out; | |
1826 | ||
d427dfeb | 1827 | /* |
96d365e0 | 1828 | * We're accessing css_set_count without locking css_set_rwsem here, |
d427dfeb TH |
1829 | * but that's OK - it can only be increased by someone holding |
1830 | * cgroup_lock, and that's us. The worst that can happen is that we | |
1831 | * have some link structures left over | |
1832 | */ | |
1833 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); | |
1834 | if (ret) | |
9d755d33 | 1835 | goto cancel_ref; |
ddbcc7e8 | 1836 | |
985ed670 | 1837 | ret = cgroup_init_root_id(root); |
ddbcc7e8 | 1838 | if (ret) |
9d755d33 | 1839 | goto cancel_ref; |
ddbcc7e8 | 1840 | |
2bd59d48 TH |
1841 | root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, |
1842 | KERNFS_ROOT_CREATE_DEACTIVATED, | |
1843 | root_cgrp); | |
1844 | if (IS_ERR(root->kf_root)) { | |
1845 | ret = PTR_ERR(root->kf_root); | |
1846 | goto exit_root_id; | |
1847 | } | |
1848 | root_cgrp->kn = root->kf_root->kn; | |
ddbcc7e8 | 1849 | |
4df8dc90 | 1850 | ret = css_populate_dir(&root_cgrp->self, NULL); |
d427dfeb | 1851 | if (ret) |
2bd59d48 | 1852 | goto destroy_root; |
ddbcc7e8 | 1853 | |
5df36032 | 1854 | ret = rebind_subsystems(root, ss_mask); |
d427dfeb | 1855 | if (ret) |
2bd59d48 | 1856 | goto destroy_root; |
ddbcc7e8 | 1857 | |
d427dfeb TH |
1858 | /* |
1859 | * There must be no failure case after here, since rebinding takes | |
1860 | * care of subsystems' refcounts, which are explicitly dropped in | |
1861 | * the failure exit path. | |
1862 | */ | |
1863 | list_add(&root->root_list, &cgroup_roots); | |
1864 | cgroup_root_count++; | |
0df6a63f | 1865 | |
d427dfeb | 1866 | /* |
3dd06ffa | 1867 | * Link the root cgroup in this hierarchy into all the css_set |
d427dfeb TH |
1868 | * objects. |
1869 | */ | |
96d365e0 | 1870 | down_write(&css_set_rwsem); |
d427dfeb TH |
1871 | hash_for_each(css_set_table, i, cset, hlist) |
1872 | link_css_set(&tmp_links, cset, root_cgrp); | |
96d365e0 | 1873 | up_write(&css_set_rwsem); |
ddbcc7e8 | 1874 | |
d5c419b6 | 1875 | BUG_ON(!list_empty(&root_cgrp->self.children)); |
3c9c825b | 1876 | BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
ddbcc7e8 | 1877 | |
2bd59d48 | 1878 | kernfs_activate(root_cgrp->kn); |
d427dfeb | 1879 | ret = 0; |
2bd59d48 | 1880 | goto out; |
d427dfeb | 1881 | |
2bd59d48 TH |
1882 | destroy_root: |
1883 | kernfs_destroy_root(root->kf_root); | |
1884 | root->kf_root = NULL; | |
1885 | exit_root_id: | |
d427dfeb | 1886 | cgroup_exit_root_id(root); |
9d755d33 | 1887 | cancel_ref: |
9a1049da | 1888 | percpu_ref_exit(&root_cgrp->self.refcnt); |
2bd59d48 | 1889 | out: |
d427dfeb TH |
1890 | free_cgrp_cset_links(&tmp_links); |
1891 | return ret; | |
ddbcc7e8 PM |
1892 | } |
1893 | ||
f7e83571 | 1894 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1895 | int flags, const char *unused_dev_name, |
f7e83571 | 1896 | void *data) |
ddbcc7e8 | 1897 | { |
3a32bd72 | 1898 | struct super_block *pinned_sb = NULL; |
970317aa | 1899 | struct cgroup_subsys *ss; |
3dd06ffa | 1900 | struct cgroup_root *root; |
ddbcc7e8 | 1901 | struct cgroup_sb_opts opts; |
2bd59d48 | 1902 | struct dentry *dentry; |
8e30e2b8 | 1903 | int ret; |
970317aa | 1904 | int i; |
c6b3d5bc | 1905 | bool new_sb; |
ddbcc7e8 | 1906 | |
56fde9e0 TH |
1907 | /* |
1908 | * The first time anyone tries to mount a cgroup, enable the list | |
1909 | * linking each css_set to its tasks and fix up all existing tasks. | |
1910 | */ | |
1911 | if (!use_task_css_set_links) | |
1912 | cgroup_enable_task_cg_lists(); | |
e37a06f1 | 1913 | |
aae8aab4 | 1914 | mutex_lock(&cgroup_mutex); |
8e30e2b8 TH |
1915 | |
1916 | /* First find the desired set of subsystems */ | |
ddbcc7e8 | 1917 | ret = parse_cgroupfs_options(data, &opts); |
c6d57f33 | 1918 | if (ret) |
8e30e2b8 | 1919 | goto out_unlock; |
a015edd2 | 1920 | |
2bd59d48 | 1921 | /* look for a matching existing root */ |
7b9a6ba5 | 1922 | if (opts.flags & CGRP_ROOT_SANE_BEHAVIOR) { |
a2dd4247 TH |
1923 | cgrp_dfl_root_visible = true; |
1924 | root = &cgrp_dfl_root; | |
1925 | cgroup_get(&root->cgrp); | |
1926 | ret = 0; | |
1927 | goto out_unlock; | |
ddbcc7e8 PM |
1928 | } |
1929 | ||
970317aa LZ |
1930 | /* |
1931 | * Destruction of cgroup root is asynchronous, so subsystems may | |
1932 | * still be dying after the previous unmount. Let's drain the | |
1933 | * dying subsystems. We just need to ensure that the ones | |
1934 | * unmounted previously finish dying and don't care about new ones | |
1935 | * starting. Testing ref liveliness is good enough. | |
1936 | */ | |
1937 | for_each_subsys(ss, i) { | |
1938 | if (!(opts.subsys_mask & (1 << i)) || | |
1939 | ss->root == &cgrp_dfl_root) | |
1940 | continue; | |
1941 | ||
1942 | if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) { | |
1943 | mutex_unlock(&cgroup_mutex); | |
1944 | msleep(10); | |
1945 | ret = restart_syscall(); | |
1946 | goto out_free; | |
1947 | } | |
1948 | cgroup_put(&ss->root->cgrp); | |
1949 | } | |
1950 | ||
985ed670 | 1951 | for_each_root(root) { |
2bd59d48 | 1952 | bool name_match = false; |
3126121f | 1953 | |
3dd06ffa | 1954 | if (root == &cgrp_dfl_root) |
985ed670 | 1955 | continue; |
3126121f | 1956 | |
cf5d5941 | 1957 | /* |
2bd59d48 TH |
1958 | * If we asked for a name then it must match. Also, if |
1959 | * name matches but sybsys_mask doesn't, we should fail. | |
1960 | * Remember whether name matched. | |
cf5d5941 | 1961 | */ |
2bd59d48 TH |
1962 | if (opts.name) { |
1963 | if (strcmp(opts.name, root->name)) | |
1964 | continue; | |
1965 | name_match = true; | |
1966 | } | |
ddbcc7e8 | 1967 | |
c6d57f33 | 1968 | /* |
2bd59d48 TH |
1969 | * If we asked for subsystems (or explicitly for no |
1970 | * subsystems) then they must match. | |
c6d57f33 | 1971 | */ |
2bd59d48 | 1972 | if ((opts.subsys_mask || opts.none) && |
f392e51c | 1973 | (opts.subsys_mask != root->subsys_mask)) { |
2bd59d48 TH |
1974 | if (!name_match) |
1975 | continue; | |
1976 | ret = -EBUSY; | |
1977 | goto out_unlock; | |
1978 | } | |
873fe09e | 1979 | |
7b9a6ba5 TH |
1980 | if (root->flags ^ opts.flags) |
1981 | pr_warn("new mount options do not match the existing superblock, will be ignored\n"); | |
ddbcc7e8 | 1982 | |
776f02fa | 1983 | /* |
3a32bd72 LZ |
1984 | * We want to reuse @root whose lifetime is governed by its |
1985 | * ->cgrp. Let's check whether @root is alive and keep it | |
1986 | * that way. As cgroup_kill_sb() can happen anytime, we | |
1987 | * want to block it by pinning the sb so that @root doesn't | |
1988 | * get killed before mount is complete. | |
1989 | * | |
1990 | * With the sb pinned, tryget_live can reliably indicate | |
1991 | * whether @root can be reused. If it's being killed, | |
1992 | * drain it. We can use wait_queue for the wait but this | |
1993 | * path is super cold. Let's just sleep a bit and retry. | |
776f02fa | 1994 | */ |
3a32bd72 LZ |
1995 | pinned_sb = kernfs_pin_sb(root->kf_root, NULL); |
1996 | if (IS_ERR(pinned_sb) || | |
1997 | !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) { | |
776f02fa | 1998 | mutex_unlock(&cgroup_mutex); |
3a32bd72 LZ |
1999 | if (!IS_ERR_OR_NULL(pinned_sb)) |
2000 | deactivate_super(pinned_sb); | |
776f02fa | 2001 | msleep(10); |
a015edd2 TH |
2002 | ret = restart_syscall(); |
2003 | goto out_free; | |
776f02fa | 2004 | } |
ddbcc7e8 | 2005 | |
776f02fa | 2006 | ret = 0; |
2bd59d48 | 2007 | goto out_unlock; |
ddbcc7e8 | 2008 | } |
ddbcc7e8 | 2009 | |
817929ec | 2010 | /* |
172a2c06 TH |
2011 | * No such thing, create a new one. name= matching without subsys |
2012 | * specification is allowed for already existing hierarchies but we | |
2013 | * can't create new one without subsys specification. | |
817929ec | 2014 | */ |
172a2c06 TH |
2015 | if (!opts.subsys_mask && !opts.none) { |
2016 | ret = -EINVAL; | |
2017 | goto out_unlock; | |
817929ec | 2018 | } |
817929ec | 2019 | |
172a2c06 TH |
2020 | root = kzalloc(sizeof(*root), GFP_KERNEL); |
2021 | if (!root) { | |
2022 | ret = -ENOMEM; | |
2bd59d48 | 2023 | goto out_unlock; |
839ec545 | 2024 | } |
e5f6a860 | 2025 | |
172a2c06 TH |
2026 | init_cgroup_root(root, &opts); |
2027 | ||
35585573 | 2028 | ret = cgroup_setup_root(root, opts.subsys_mask); |
2bd59d48 TH |
2029 | if (ret) |
2030 | cgroup_free_root(root); | |
fa3ca07e | 2031 | |
8e30e2b8 | 2032 | out_unlock: |
ddbcc7e8 | 2033 | mutex_unlock(&cgroup_mutex); |
a015edd2 | 2034 | out_free: |
c6d57f33 PM |
2035 | kfree(opts.release_agent); |
2036 | kfree(opts.name); | |
03b1cde6 | 2037 | |
2bd59d48 | 2038 | if (ret) |
8e30e2b8 | 2039 | return ERR_PTR(ret); |
2bd59d48 | 2040 | |
c9482a5b JZ |
2041 | dentry = kernfs_mount(fs_type, flags, root->kf_root, |
2042 | CGROUP_SUPER_MAGIC, &new_sb); | |
c6b3d5bc | 2043 | if (IS_ERR(dentry) || !new_sb) |
3dd06ffa | 2044 | cgroup_put(&root->cgrp); |
3a32bd72 LZ |
2045 | |
2046 | /* | |
2047 | * If @pinned_sb, we're reusing an existing root and holding an | |
2048 | * extra ref on its sb. Mount is complete. Put the extra ref. | |
2049 | */ | |
2050 | if (pinned_sb) { | |
2051 | WARN_ON(new_sb); | |
2052 | deactivate_super(pinned_sb); | |
2053 | } | |
2054 | ||
2bd59d48 TH |
2055 | return dentry; |
2056 | } | |
2057 | ||
2058 | static void cgroup_kill_sb(struct super_block *sb) | |
2059 | { | |
2060 | struct kernfs_root *kf_root = kernfs_root_from_sb(sb); | |
3dd06ffa | 2061 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
2bd59d48 | 2062 | |
9d755d33 TH |
2063 | /* |
2064 | * If @root doesn't have any mounts or children, start killing it. | |
2065 | * This prevents new mounts by disabling percpu_ref_tryget_live(). | |
2066 | * cgroup_mount() may wait for @root's release. | |
1f779fb2 LZ |
2067 | * |
2068 | * And don't kill the default root. | |
9d755d33 | 2069 | */ |
3c606d35 | 2070 | if (!list_empty(&root->cgrp.self.children) || |
1f779fb2 | 2071 | root == &cgrp_dfl_root) |
9d755d33 TH |
2072 | cgroup_put(&root->cgrp); |
2073 | else | |
2074 | percpu_ref_kill(&root->cgrp.self.refcnt); | |
2075 | ||
2bd59d48 | 2076 | kernfs_kill_sb(sb); |
ddbcc7e8 PM |
2077 | } |
2078 | ||
2079 | static struct file_system_type cgroup_fs_type = { | |
2080 | .name = "cgroup", | |
f7e83571 | 2081 | .mount = cgroup_mount, |
ddbcc7e8 PM |
2082 | .kill_sb = cgroup_kill_sb, |
2083 | }; | |
2084 | ||
857a2beb | 2085 | /** |
913ffdb5 | 2086 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
857a2beb | 2087 | * @task: target task |
857a2beb TH |
2088 | * @buf: the buffer to write the path into |
2089 | * @buflen: the length of the buffer | |
2090 | * | |
913ffdb5 TH |
2091 | * Determine @task's cgroup on the first (the one with the lowest non-zero |
2092 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This | |
2093 | * function grabs cgroup_mutex and shouldn't be used inside locks used by | |
2094 | * cgroup controller callbacks. | |
2095 | * | |
e61734c5 | 2096 | * Return value is the same as kernfs_path(). |
857a2beb | 2097 | */ |
e61734c5 | 2098 | char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
857a2beb | 2099 | { |
3dd06ffa | 2100 | struct cgroup_root *root; |
913ffdb5 | 2101 | struct cgroup *cgrp; |
e61734c5 TH |
2102 | int hierarchy_id = 1; |
2103 | char *path = NULL; | |
857a2beb TH |
2104 | |
2105 | mutex_lock(&cgroup_mutex); | |
96d365e0 | 2106 | down_read(&css_set_rwsem); |
857a2beb | 2107 | |
913ffdb5 TH |
2108 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
2109 | ||
857a2beb TH |
2110 | if (root) { |
2111 | cgrp = task_cgroup_from_root(task, root); | |
e61734c5 | 2112 | path = cgroup_path(cgrp, buf, buflen); |
913ffdb5 TH |
2113 | } else { |
2114 | /* if no hierarchy exists, everyone is in "/" */ | |
e61734c5 TH |
2115 | if (strlcpy(buf, "/", buflen) < buflen) |
2116 | path = buf; | |
857a2beb TH |
2117 | } |
2118 | ||
96d365e0 | 2119 | up_read(&css_set_rwsem); |
857a2beb | 2120 | mutex_unlock(&cgroup_mutex); |
e61734c5 | 2121 | return path; |
857a2beb | 2122 | } |
913ffdb5 | 2123 | EXPORT_SYMBOL_GPL(task_cgroup_path); |
857a2beb | 2124 | |
b3dc094e | 2125 | /* used to track tasks and other necessary states during migration */ |
2f7ee569 | 2126 | struct cgroup_taskset { |
b3dc094e TH |
2127 | /* the src and dst cset list running through cset->mg_node */ |
2128 | struct list_head src_csets; | |
2129 | struct list_head dst_csets; | |
2130 | ||
2131 | /* | |
2132 | * Fields for cgroup_taskset_*() iteration. | |
2133 | * | |
2134 | * Before migration is committed, the target migration tasks are on | |
2135 | * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of | |
2136 | * the csets on ->dst_csets. ->csets point to either ->src_csets | |
2137 | * or ->dst_csets depending on whether migration is committed. | |
2138 | * | |
2139 | * ->cur_csets and ->cur_task point to the current task position | |
2140 | * during iteration. | |
2141 | */ | |
2142 | struct list_head *csets; | |
2143 | struct css_set *cur_cset; | |
2144 | struct task_struct *cur_task; | |
2f7ee569 TH |
2145 | }; |
2146 | ||
adaae5dc TH |
2147 | #define CGROUP_TASKSET_INIT(tset) (struct cgroup_taskset){ \ |
2148 | .src_csets = LIST_HEAD_INIT(tset.src_csets), \ | |
2149 | .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \ | |
2150 | .csets = &tset.src_csets, \ | |
2151 | } | |
2152 | ||
2153 | /** | |
2154 | * cgroup_taskset_add - try to add a migration target task to a taskset | |
2155 | * @task: target task | |
2156 | * @tset: target taskset | |
2157 | * | |
2158 | * Add @task, which is a migration target, to @tset. This function becomes | |
2159 | * noop if @task doesn't need to be migrated. @task's css_set should have | |
2160 | * been added as a migration source and @task->cg_list will be moved from | |
2161 | * the css_set's tasks list to mg_tasks one. | |
2162 | */ | |
2163 | static void cgroup_taskset_add(struct task_struct *task, | |
2164 | struct cgroup_taskset *tset) | |
2165 | { | |
2166 | struct css_set *cset; | |
2167 | ||
2168 | lockdep_assert_held(&css_set_rwsem); | |
2169 | ||
2170 | /* @task either already exited or can't exit until the end */ | |
2171 | if (task->flags & PF_EXITING) | |
2172 | return; | |
2173 | ||
2174 | /* leave @task alone if post_fork() hasn't linked it yet */ | |
2175 | if (list_empty(&task->cg_list)) | |
2176 | return; | |
2177 | ||
2178 | cset = task_css_set(task); | |
2179 | if (!cset->mg_src_cgrp) | |
2180 | return; | |
2181 | ||
2182 | list_move_tail(&task->cg_list, &cset->mg_tasks); | |
2183 | if (list_empty(&cset->mg_node)) | |
2184 | list_add_tail(&cset->mg_node, &tset->src_csets); | |
2185 | if (list_empty(&cset->mg_dst_cset->mg_node)) | |
2186 | list_move_tail(&cset->mg_dst_cset->mg_node, | |
2187 | &tset->dst_csets); | |
2188 | } | |
2189 | ||
2f7ee569 TH |
2190 | /** |
2191 | * cgroup_taskset_first - reset taskset and return the first task | |
2192 | * @tset: taskset of interest | |
2193 | * | |
2194 | * @tset iteration is initialized and the first task is returned. | |
2195 | */ | |
2196 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
2197 | { | |
b3dc094e TH |
2198 | tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
2199 | tset->cur_task = NULL; | |
2200 | ||
2201 | return cgroup_taskset_next(tset); | |
2f7ee569 | 2202 | } |
2f7ee569 TH |
2203 | |
2204 | /** | |
2205 | * cgroup_taskset_next - iterate to the next task in taskset | |
2206 | * @tset: taskset of interest | |
2207 | * | |
2208 | * Return the next task in @tset. Iteration must have been initialized | |
2209 | * with cgroup_taskset_first(). | |
2210 | */ | |
2211 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
2212 | { | |
b3dc094e TH |
2213 | struct css_set *cset = tset->cur_cset; |
2214 | struct task_struct *task = tset->cur_task; | |
2f7ee569 | 2215 | |
b3dc094e TH |
2216 | while (&cset->mg_node != tset->csets) { |
2217 | if (!task) | |
2218 | task = list_first_entry(&cset->mg_tasks, | |
2219 | struct task_struct, cg_list); | |
2220 | else | |
2221 | task = list_next_entry(task, cg_list); | |
2f7ee569 | 2222 | |
b3dc094e TH |
2223 | if (&task->cg_list != &cset->mg_tasks) { |
2224 | tset->cur_cset = cset; | |
2225 | tset->cur_task = task; | |
2226 | return task; | |
2227 | } | |
2f7ee569 | 2228 | |
b3dc094e TH |
2229 | cset = list_next_entry(cset, mg_node); |
2230 | task = NULL; | |
2231 | } | |
2f7ee569 | 2232 | |
b3dc094e | 2233 | return NULL; |
2f7ee569 | 2234 | } |
2f7ee569 | 2235 | |
cb0f1fe9 | 2236 | /** |
74a1166d | 2237 | * cgroup_task_migrate - move a task from one cgroup to another. |
60106946 | 2238 | * @old_cgrp: the cgroup @tsk is being migrated from |
cb0f1fe9 TH |
2239 | * @tsk: the task being migrated |
2240 | * @new_cset: the new css_set @tsk is being attached to | |
74a1166d | 2241 | * |
cb0f1fe9 | 2242 | * Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked. |
74a1166d | 2243 | */ |
5abb8855 TH |
2244 | static void cgroup_task_migrate(struct cgroup *old_cgrp, |
2245 | struct task_struct *tsk, | |
2246 | struct css_set *new_cset) | |
74a1166d | 2247 | { |
5abb8855 | 2248 | struct css_set *old_cset; |
74a1166d | 2249 | |
cb0f1fe9 TH |
2250 | lockdep_assert_held(&cgroup_mutex); |
2251 | lockdep_assert_held(&css_set_rwsem); | |
2252 | ||
74a1166d | 2253 | /* |
1ed13287 TH |
2254 | * We are synchronized through cgroup_threadgroup_rwsem against |
2255 | * PF_EXITING setting such that we can't race against cgroup_exit() | |
2256 | * changing the css_set to init_css_set and dropping the old one. | |
74a1166d | 2257 | */ |
c84cdf75 | 2258 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
a8ad805c | 2259 | old_cset = task_css_set(tsk); |
74a1166d | 2260 | |
b3dc094e | 2261 | get_css_set(new_cset); |
5abb8855 | 2262 | rcu_assign_pointer(tsk->cgroups, new_cset); |
1b9aba49 | 2263 | list_move_tail(&tsk->cg_list, &new_cset->mg_tasks); |
74a1166d BB |
2264 | |
2265 | /* | |
5abb8855 TH |
2266 | * We just gained a reference on old_cset by taking it from the |
2267 | * task. As trading it for new_cset is protected by cgroup_mutex, | |
2268 | * we're safe to drop it here; it will be freed under RCU. | |
74a1166d | 2269 | */ |
a25eb52e | 2270 | put_css_set_locked(old_cset); |
74a1166d BB |
2271 | } |
2272 | ||
adaae5dc TH |
2273 | /** |
2274 | * cgroup_taskset_migrate - migrate a taskset to a cgroup | |
2275 | * @tset: taget taskset | |
2276 | * @dst_cgrp: destination cgroup | |
2277 | * | |
2278 | * Migrate tasks in @tset to @dst_cgrp. This function fails iff one of the | |
2279 | * ->can_attach callbacks fails and guarantees that either all or none of | |
2280 | * the tasks in @tset are migrated. @tset is consumed regardless of | |
2281 | * success. | |
2282 | */ | |
2283 | static int cgroup_taskset_migrate(struct cgroup_taskset *tset, | |
2284 | struct cgroup *dst_cgrp) | |
2285 | { | |
2286 | struct cgroup_subsys_state *css, *failed_css = NULL; | |
2287 | struct task_struct *task, *tmp_task; | |
2288 | struct css_set *cset, *tmp_cset; | |
2289 | int i, ret; | |
2290 | ||
2291 | /* methods shouldn't be called if no task is actually migrating */ | |
2292 | if (list_empty(&tset->src_csets)) | |
2293 | return 0; | |
2294 | ||
2295 | /* check that we can legitimately attach to the cgroup */ | |
2296 | for_each_e_css(css, i, dst_cgrp) { | |
2297 | if (css->ss->can_attach) { | |
2298 | ret = css->ss->can_attach(css, tset); | |
2299 | if (ret) { | |
2300 | failed_css = css; | |
2301 | goto out_cancel_attach; | |
2302 | } | |
2303 | } | |
2304 | } | |
2305 | ||
2306 | /* | |
2307 | * Now that we're guaranteed success, proceed to move all tasks to | |
2308 | * the new cgroup. There are no failure cases after here, so this | |
2309 | * is the commit point. | |
2310 | */ | |
2311 | down_write(&css_set_rwsem); | |
2312 | list_for_each_entry(cset, &tset->src_csets, mg_node) { | |
2313 | list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) | |
2314 | cgroup_task_migrate(cset->mg_src_cgrp, task, | |
2315 | cset->mg_dst_cset); | |
2316 | } | |
2317 | up_write(&css_set_rwsem); | |
2318 | ||
2319 | /* | |
2320 | * Migration is committed, all target tasks are now on dst_csets. | |
2321 | * Nothing is sensitive to fork() after this point. Notify | |
2322 | * controllers that migration is complete. | |
2323 | */ | |
2324 | tset->csets = &tset->dst_csets; | |
2325 | ||
2326 | for_each_e_css(css, i, dst_cgrp) | |
2327 | if (css->ss->attach) | |
2328 | css->ss->attach(css, tset); | |
2329 | ||
2330 | ret = 0; | |
2331 | goto out_release_tset; | |
2332 | ||
2333 | out_cancel_attach: | |
2334 | for_each_e_css(css, i, dst_cgrp) { | |
2335 | if (css == failed_css) | |
2336 | break; | |
2337 | if (css->ss->cancel_attach) | |
2338 | css->ss->cancel_attach(css, tset); | |
2339 | } | |
2340 | out_release_tset: | |
2341 | down_write(&css_set_rwsem); | |
2342 | list_splice_init(&tset->dst_csets, &tset->src_csets); | |
2343 | list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) { | |
2344 | list_splice_tail_init(&cset->mg_tasks, &cset->tasks); | |
2345 | list_del_init(&cset->mg_node); | |
2346 | } | |
2347 | up_write(&css_set_rwsem); | |
2348 | return ret; | |
2349 | } | |
2350 | ||
a043e3b2 | 2351 | /** |
1958d2d5 TH |
2352 | * cgroup_migrate_finish - cleanup after attach |
2353 | * @preloaded_csets: list of preloaded css_sets | |
74a1166d | 2354 | * |
1958d2d5 TH |
2355 | * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
2356 | * those functions for details. | |
74a1166d | 2357 | */ |
1958d2d5 | 2358 | static void cgroup_migrate_finish(struct list_head *preloaded_csets) |
74a1166d | 2359 | { |
1958d2d5 | 2360 | struct css_set *cset, *tmp_cset; |
74a1166d | 2361 | |
1958d2d5 TH |
2362 | lockdep_assert_held(&cgroup_mutex); |
2363 | ||
2364 | down_write(&css_set_rwsem); | |
2365 | list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) { | |
2366 | cset->mg_src_cgrp = NULL; | |
2367 | cset->mg_dst_cset = NULL; | |
2368 | list_del_init(&cset->mg_preload_node); | |
a25eb52e | 2369 | put_css_set_locked(cset); |
1958d2d5 TH |
2370 | } |
2371 | up_write(&css_set_rwsem); | |
2372 | } | |
2373 | ||
2374 | /** | |
2375 | * cgroup_migrate_add_src - add a migration source css_set | |
2376 | * @src_cset: the source css_set to add | |
2377 | * @dst_cgrp: the destination cgroup | |
2378 | * @preloaded_csets: list of preloaded css_sets | |
2379 | * | |
2380 | * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin | |
2381 | * @src_cset and add it to @preloaded_csets, which should later be cleaned | |
2382 | * up by cgroup_migrate_finish(). | |
2383 | * | |
1ed13287 TH |
2384 | * This function may be called without holding cgroup_threadgroup_rwsem |
2385 | * even if the target is a process. Threads may be created and destroyed | |
2386 | * but as long as cgroup_mutex is not dropped, no new css_set can be put | |
2387 | * into play and the preloaded css_sets are guaranteed to cover all | |
2388 | * migrations. | |
1958d2d5 TH |
2389 | */ |
2390 | static void cgroup_migrate_add_src(struct css_set *src_cset, | |
2391 | struct cgroup *dst_cgrp, | |
2392 | struct list_head *preloaded_csets) | |
2393 | { | |
2394 | struct cgroup *src_cgrp; | |
2395 | ||
2396 | lockdep_assert_held(&cgroup_mutex); | |
2397 | lockdep_assert_held(&css_set_rwsem); | |
2398 | ||
2399 | src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); | |
2400 | ||
1958d2d5 TH |
2401 | if (!list_empty(&src_cset->mg_preload_node)) |
2402 | return; | |
2403 | ||
2404 | WARN_ON(src_cset->mg_src_cgrp); | |
2405 | WARN_ON(!list_empty(&src_cset->mg_tasks)); | |
2406 | WARN_ON(!list_empty(&src_cset->mg_node)); | |
2407 | ||
2408 | src_cset->mg_src_cgrp = src_cgrp; | |
2409 | get_css_set(src_cset); | |
2410 | list_add(&src_cset->mg_preload_node, preloaded_csets); | |
2411 | } | |
2412 | ||
2413 | /** | |
2414 | * cgroup_migrate_prepare_dst - prepare destination css_sets for migration | |
f817de98 | 2415 | * @dst_cgrp: the destination cgroup (may be %NULL) |
1958d2d5 TH |
2416 | * @preloaded_csets: list of preloaded source css_sets |
2417 | * | |
2418 | * Tasks are about to be moved to @dst_cgrp and all the source css_sets | |
2419 | * have been preloaded to @preloaded_csets. This function looks up and | |
f817de98 TH |
2420 | * pins all destination css_sets, links each to its source, and append them |
2421 | * to @preloaded_csets. If @dst_cgrp is %NULL, the destination of each | |
2422 | * source css_set is assumed to be its cgroup on the default hierarchy. | |
1958d2d5 TH |
2423 | * |
2424 | * This function must be called after cgroup_migrate_add_src() has been | |
2425 | * called on each migration source css_set. After migration is performed | |
2426 | * using cgroup_migrate(), cgroup_migrate_finish() must be called on | |
2427 | * @preloaded_csets. | |
2428 | */ | |
2429 | static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, | |
2430 | struct list_head *preloaded_csets) | |
2431 | { | |
2432 | LIST_HEAD(csets); | |
f817de98 | 2433 | struct css_set *src_cset, *tmp_cset; |
1958d2d5 TH |
2434 | |
2435 | lockdep_assert_held(&cgroup_mutex); | |
2436 | ||
f8f22e53 TH |
2437 | /* |
2438 | * Except for the root, child_subsys_mask must be zero for a cgroup | |
2439 | * with tasks so that child cgroups don't compete against tasks. | |
2440 | */ | |
d51f39b0 | 2441 | if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) && |
f8f22e53 TH |
2442 | dst_cgrp->child_subsys_mask) |
2443 | return -EBUSY; | |
2444 | ||
1958d2d5 | 2445 | /* look up the dst cset for each src cset and link it to src */ |
f817de98 | 2446 | list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) { |
1958d2d5 TH |
2447 | struct css_set *dst_cset; |
2448 | ||
f817de98 TH |
2449 | dst_cset = find_css_set(src_cset, |
2450 | dst_cgrp ?: src_cset->dfl_cgrp); | |
1958d2d5 TH |
2451 | if (!dst_cset) |
2452 | goto err; | |
2453 | ||
2454 | WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); | |
f817de98 TH |
2455 | |
2456 | /* | |
2457 | * If src cset equals dst, it's noop. Drop the src. | |
2458 | * cgroup_migrate() will skip the cset too. Note that we | |
2459 | * can't handle src == dst as some nodes are used by both. | |
2460 | */ | |
2461 | if (src_cset == dst_cset) { | |
2462 | src_cset->mg_src_cgrp = NULL; | |
2463 | list_del_init(&src_cset->mg_preload_node); | |
a25eb52e ZL |
2464 | put_css_set(src_cset); |
2465 | put_css_set(dst_cset); | |
f817de98 TH |
2466 | continue; |
2467 | } | |
2468 | ||
1958d2d5 TH |
2469 | src_cset->mg_dst_cset = dst_cset; |
2470 | ||
2471 | if (list_empty(&dst_cset->mg_preload_node)) | |
2472 | list_add(&dst_cset->mg_preload_node, &csets); | |
2473 | else | |
a25eb52e | 2474 | put_css_set(dst_cset); |
1958d2d5 TH |
2475 | } |
2476 | ||
f817de98 | 2477 | list_splice_tail(&csets, preloaded_csets); |
1958d2d5 TH |
2478 | return 0; |
2479 | err: | |
2480 | cgroup_migrate_finish(&csets); | |
2481 | return -ENOMEM; | |
2482 | } | |
2483 | ||
2484 | /** | |
2485 | * cgroup_migrate - migrate a process or task to a cgroup | |
1958d2d5 TH |
2486 | * @leader: the leader of the process or the task to migrate |
2487 | * @threadgroup: whether @leader points to the whole process or a single task | |
9af2ec45 | 2488 | * @cgrp: the destination cgroup |
1958d2d5 TH |
2489 | * |
2490 | * Migrate a process or task denoted by @leader to @cgrp. If migrating a | |
1ed13287 | 2491 | * process, the caller must be holding cgroup_threadgroup_rwsem. The |
1958d2d5 TH |
2492 | * caller is also responsible for invoking cgroup_migrate_add_src() and |
2493 | * cgroup_migrate_prepare_dst() on the targets before invoking this | |
2494 | * function and following up with cgroup_migrate_finish(). | |
2495 | * | |
2496 | * As long as a controller's ->can_attach() doesn't fail, this function is | |
2497 | * guaranteed to succeed. This means that, excluding ->can_attach() | |
2498 | * failure, when migrating multiple targets, the success or failure can be | |
2499 | * decided for all targets by invoking group_migrate_prepare_dst() before | |
2500 | * actually starting migrating. | |
2501 | */ | |
9af2ec45 TH |
2502 | static int cgroup_migrate(struct task_struct *leader, bool threadgroup, |
2503 | struct cgroup *cgrp) | |
74a1166d | 2504 | { |
adaae5dc TH |
2505 | struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); |
2506 | struct task_struct *task; | |
74a1166d | 2507 | |
fb5d2b4c MSB |
2508 | /* |
2509 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
2510 | * already PF_EXITING could be freed from underneath us unless we | |
2511 | * take an rcu_read_lock. | |
2512 | */ | |
b3dc094e | 2513 | down_write(&css_set_rwsem); |
fb5d2b4c | 2514 | rcu_read_lock(); |
9db8de37 | 2515 | task = leader; |
74a1166d | 2516 | do { |
adaae5dc | 2517 | cgroup_taskset_add(task, &tset); |
081aa458 LZ |
2518 | if (!threadgroup) |
2519 | break; | |
9db8de37 | 2520 | } while_each_thread(leader, task); |
fb5d2b4c | 2521 | rcu_read_unlock(); |
b3dc094e | 2522 | up_write(&css_set_rwsem); |
74a1166d | 2523 | |
adaae5dc | 2524 | return cgroup_taskset_migrate(&tset, cgrp); |
74a1166d BB |
2525 | } |
2526 | ||
1958d2d5 TH |
2527 | /** |
2528 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup | |
2529 | * @dst_cgrp: the cgroup to attach to | |
2530 | * @leader: the task or the leader of the threadgroup to be attached | |
2531 | * @threadgroup: attach the whole threadgroup? | |
2532 | * | |
1ed13287 | 2533 | * Call holding cgroup_mutex and cgroup_threadgroup_rwsem. |
1958d2d5 TH |
2534 | */ |
2535 | static int cgroup_attach_task(struct cgroup *dst_cgrp, | |
2536 | struct task_struct *leader, bool threadgroup) | |
2537 | { | |
2538 | LIST_HEAD(preloaded_csets); | |
2539 | struct task_struct *task; | |
2540 | int ret; | |
2541 | ||
2542 | /* look up all src csets */ | |
2543 | down_read(&css_set_rwsem); | |
2544 | rcu_read_lock(); | |
2545 | task = leader; | |
2546 | do { | |
2547 | cgroup_migrate_add_src(task_css_set(task), dst_cgrp, | |
2548 | &preloaded_csets); | |
2549 | if (!threadgroup) | |
2550 | break; | |
2551 | } while_each_thread(leader, task); | |
2552 | rcu_read_unlock(); | |
2553 | up_read(&css_set_rwsem); | |
2554 | ||
2555 | /* prepare dst csets and commit */ | |
2556 | ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets); | |
2557 | if (!ret) | |
9af2ec45 | 2558 | ret = cgroup_migrate(leader, threadgroup, dst_cgrp); |
1958d2d5 TH |
2559 | |
2560 | cgroup_migrate_finish(&preloaded_csets); | |
2561 | return ret; | |
74a1166d BB |
2562 | } |
2563 | ||
187fe840 TH |
2564 | static int cgroup_procs_write_permission(struct task_struct *task, |
2565 | struct cgroup *dst_cgrp, | |
2566 | struct kernfs_open_file *of) | |
dedf22e9 TH |
2567 | { |
2568 | const struct cred *cred = current_cred(); | |
2569 | const struct cred *tcred = get_task_cred(task); | |
2570 | int ret = 0; | |
2571 | ||
2572 | /* | |
2573 | * even if we're attaching all tasks in the thread group, we only | |
2574 | * need to check permissions on one of them. | |
2575 | */ | |
2576 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && | |
2577 | !uid_eq(cred->euid, tcred->uid) && | |
2578 | !uid_eq(cred->euid, tcred->suid)) | |
2579 | ret = -EACCES; | |
2580 | ||
187fe840 TH |
2581 | if (!ret && cgroup_on_dfl(dst_cgrp)) { |
2582 | struct super_block *sb = of->file->f_path.dentry->d_sb; | |
2583 | struct cgroup *cgrp; | |
2584 | struct inode *inode; | |
2585 | ||
2586 | down_read(&css_set_rwsem); | |
2587 | cgrp = task_cgroup_from_root(task, &cgrp_dfl_root); | |
2588 | up_read(&css_set_rwsem); | |
2589 | ||
2590 | while (!cgroup_is_descendant(dst_cgrp, cgrp)) | |
2591 | cgrp = cgroup_parent(cgrp); | |
2592 | ||
2593 | ret = -ENOMEM; | |
6f60eade | 2594 | inode = kernfs_get_inode(sb, cgrp->procs_file.kn); |
187fe840 TH |
2595 | if (inode) { |
2596 | ret = inode_permission(inode, MAY_WRITE); | |
2597 | iput(inode); | |
2598 | } | |
2599 | } | |
2600 | ||
dedf22e9 TH |
2601 | put_cred(tcred); |
2602 | return ret; | |
2603 | } | |
2604 | ||
74a1166d BB |
2605 | /* |
2606 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 | 2607 | * function to attach either it or all tasks in its threadgroup. Will lock |
0e1d768f | 2608 | * cgroup_mutex and threadgroup. |
bbcb81d0 | 2609 | */ |
acbef755 TH |
2610 | static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, |
2611 | size_t nbytes, loff_t off, bool threadgroup) | |
bbcb81d0 | 2612 | { |
bbcb81d0 | 2613 | struct task_struct *tsk; |
e76ecaee | 2614 | struct cgroup *cgrp; |
acbef755 | 2615 | pid_t pid; |
bbcb81d0 PM |
2616 | int ret; |
2617 | ||
acbef755 TH |
2618 | if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) |
2619 | return -EINVAL; | |
2620 | ||
e76ecaee TH |
2621 | cgrp = cgroup_kn_lock_live(of->kn); |
2622 | if (!cgrp) | |
74a1166d BB |
2623 | return -ENODEV; |
2624 | ||
3014dde7 | 2625 | percpu_down_write(&cgroup_threadgroup_rwsem); |
b78949eb | 2626 | rcu_read_lock(); |
bbcb81d0 | 2627 | if (pid) { |
73507f33 | 2628 | tsk = find_task_by_vpid(pid); |
74a1166d | 2629 | if (!tsk) { |
dd4b0a46 | 2630 | ret = -ESRCH; |
3014dde7 | 2631 | goto out_unlock_rcu; |
bbcb81d0 | 2632 | } |
dedf22e9 | 2633 | } else { |
b78949eb | 2634 | tsk = current; |
dedf22e9 | 2635 | } |
cd3d0952 TH |
2636 | |
2637 | if (threadgroup) | |
b78949eb | 2638 | tsk = tsk->group_leader; |
c4c27fbd MG |
2639 | |
2640 | /* | |
14a40ffc | 2641 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2642 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2643 | * with no rt_runtime allocated. Just say no. | |
2644 | */ | |
14a40ffc | 2645 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd | 2646 | ret = -EINVAL; |
3014dde7 | 2647 | goto out_unlock_rcu; |
c4c27fbd MG |
2648 | } |
2649 | ||
b78949eb MSB |
2650 | get_task_struct(tsk); |
2651 | rcu_read_unlock(); | |
2652 | ||
187fe840 | 2653 | ret = cgroup_procs_write_permission(tsk, cgrp, of); |
dedf22e9 TH |
2654 | if (!ret) |
2655 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
081aa458 | 2656 | |
f9f9e7b7 | 2657 | put_task_struct(tsk); |
3014dde7 TH |
2658 | goto out_unlock_threadgroup; |
2659 | ||
2660 | out_unlock_rcu: | |
2661 | rcu_read_unlock(); | |
2662 | out_unlock_threadgroup: | |
2663 | percpu_up_write(&cgroup_threadgroup_rwsem); | |
e76ecaee | 2664 | cgroup_kn_unlock(of->kn); |
acbef755 | 2665 | return ret ?: nbytes; |
bbcb81d0 PM |
2666 | } |
2667 | ||
7ae1bad9 TH |
2668 | /** |
2669 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2670 | * @from: attach to all cgroups of a given task | |
2671 | * @tsk: the task to be attached | |
2672 | */ | |
2673 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2674 | { | |
3dd06ffa | 2675 | struct cgroup_root *root; |
7ae1bad9 TH |
2676 | int retval = 0; |
2677 | ||
47cfcd09 | 2678 | mutex_lock(&cgroup_mutex); |
985ed670 | 2679 | for_each_root(root) { |
96d365e0 TH |
2680 | struct cgroup *from_cgrp; |
2681 | ||
3dd06ffa | 2682 | if (root == &cgrp_dfl_root) |
985ed670 TH |
2683 | continue; |
2684 | ||
96d365e0 TH |
2685 | down_read(&css_set_rwsem); |
2686 | from_cgrp = task_cgroup_from_root(from, root); | |
2687 | up_read(&css_set_rwsem); | |
7ae1bad9 | 2688 | |
6f4b7e63 | 2689 | retval = cgroup_attach_task(from_cgrp, tsk, false); |
7ae1bad9 TH |
2690 | if (retval) |
2691 | break; | |
2692 | } | |
47cfcd09 | 2693 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2694 | |
2695 | return retval; | |
2696 | } | |
2697 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2698 | ||
acbef755 TH |
2699 | static ssize_t cgroup_tasks_write(struct kernfs_open_file *of, |
2700 | char *buf, size_t nbytes, loff_t off) | |
74a1166d | 2701 | { |
acbef755 | 2702 | return __cgroup_procs_write(of, buf, nbytes, off, false); |
74a1166d BB |
2703 | } |
2704 | ||
acbef755 TH |
2705 | static ssize_t cgroup_procs_write(struct kernfs_open_file *of, |
2706 | char *buf, size_t nbytes, loff_t off) | |
af351026 | 2707 | { |
acbef755 | 2708 | return __cgroup_procs_write(of, buf, nbytes, off, true); |
af351026 PM |
2709 | } |
2710 | ||
451af504 TH |
2711 | static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, |
2712 | char *buf, size_t nbytes, loff_t off) | |
e788e066 | 2713 | { |
e76ecaee | 2714 | struct cgroup *cgrp; |
5f469907 | 2715 | |
e76ecaee | 2716 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); |
5f469907 | 2717 | |
e76ecaee TH |
2718 | cgrp = cgroup_kn_lock_live(of->kn); |
2719 | if (!cgrp) | |
e788e066 | 2720 | return -ENODEV; |
69e943b7 | 2721 | spin_lock(&release_agent_path_lock); |
e76ecaee TH |
2722 | strlcpy(cgrp->root->release_agent_path, strstrip(buf), |
2723 | sizeof(cgrp->root->release_agent_path)); | |
69e943b7 | 2724 | spin_unlock(&release_agent_path_lock); |
e76ecaee | 2725 | cgroup_kn_unlock(of->kn); |
451af504 | 2726 | return nbytes; |
e788e066 PM |
2727 | } |
2728 | ||
2da8ca82 | 2729 | static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
e788e066 | 2730 | { |
2da8ca82 | 2731 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
182446d0 | 2732 | |
46cfeb04 | 2733 | spin_lock(&release_agent_path_lock); |
e788e066 | 2734 | seq_puts(seq, cgrp->root->release_agent_path); |
46cfeb04 | 2735 | spin_unlock(&release_agent_path_lock); |
e788e066 | 2736 | seq_putc(seq, '\n'); |
e788e066 PM |
2737 | return 0; |
2738 | } | |
2739 | ||
2da8ca82 | 2740 | static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
873fe09e | 2741 | { |
c1d5d42e | 2742 | seq_puts(seq, "0\n"); |
e788e066 PM |
2743 | return 0; |
2744 | } | |
2745 | ||
8ab456ac | 2746 | static void cgroup_print_ss_mask(struct seq_file *seq, unsigned long ss_mask) |
355e0c48 | 2747 | { |
f8f22e53 TH |
2748 | struct cgroup_subsys *ss; |
2749 | bool printed = false; | |
2750 | int ssid; | |
a742c59d | 2751 | |
a966a4ed AS |
2752 | for_each_subsys_which(ss, ssid, &ss_mask) { |
2753 | if (printed) | |
2754 | seq_putc(seq, ' '); | |
2755 | seq_printf(seq, "%s", ss->name); | |
2756 | printed = true; | |
e73d2c61 | 2757 | } |
f8f22e53 TH |
2758 | if (printed) |
2759 | seq_putc(seq, '\n'); | |
355e0c48 PM |
2760 | } |
2761 | ||
f8f22e53 TH |
2762 | /* show controllers which are currently attached to the default hierarchy */ |
2763 | static int cgroup_root_controllers_show(struct seq_file *seq, void *v) | |
db3b1497 | 2764 | { |
f8f22e53 TH |
2765 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2766 | ||
5533e011 TH |
2767 | cgroup_print_ss_mask(seq, cgrp->root->subsys_mask & |
2768 | ~cgrp_dfl_root_inhibit_ss_mask); | |
f8f22e53 | 2769 | return 0; |
db3b1497 PM |
2770 | } |
2771 | ||
f8f22e53 TH |
2772 | /* show controllers which are enabled from the parent */ |
2773 | static int cgroup_controllers_show(struct seq_file *seq, void *v) | |
ddbcc7e8 | 2774 | { |
f8f22e53 TH |
2775 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2776 | ||
667c2491 | 2777 | cgroup_print_ss_mask(seq, cgroup_parent(cgrp)->subtree_control); |
f8f22e53 | 2778 | return 0; |
ddbcc7e8 PM |
2779 | } |
2780 | ||
f8f22e53 TH |
2781 | /* show controllers which are enabled for a given cgroup's children */ |
2782 | static int cgroup_subtree_control_show(struct seq_file *seq, void *v) | |
ddbcc7e8 | 2783 | { |
f8f22e53 TH |
2784 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2785 | ||
667c2491 | 2786 | cgroup_print_ss_mask(seq, cgrp->subtree_control); |
f8f22e53 TH |
2787 | return 0; |
2788 | } | |
2789 | ||
2790 | /** | |
2791 | * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy | |
2792 | * @cgrp: root of the subtree to update csses for | |
2793 | * | |
2794 | * @cgrp's child_subsys_mask has changed and its subtree's (self excluded) | |
2795 | * css associations need to be updated accordingly. This function looks up | |
2796 | * all css_sets which are attached to the subtree, creates the matching | |
2797 | * updated css_sets and migrates the tasks to the new ones. | |
2798 | */ | |
2799 | static int cgroup_update_dfl_csses(struct cgroup *cgrp) | |
2800 | { | |
2801 | LIST_HEAD(preloaded_csets); | |
10265075 | 2802 | struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); |
f8f22e53 TH |
2803 | struct cgroup_subsys_state *css; |
2804 | struct css_set *src_cset; | |
2805 | int ret; | |
2806 | ||
f8f22e53 TH |
2807 | lockdep_assert_held(&cgroup_mutex); |
2808 | ||
3014dde7 TH |
2809 | percpu_down_write(&cgroup_threadgroup_rwsem); |
2810 | ||
f8f22e53 TH |
2811 | /* look up all csses currently attached to @cgrp's subtree */ |
2812 | down_read(&css_set_rwsem); | |
2813 | css_for_each_descendant_pre(css, cgroup_css(cgrp, NULL)) { | |
2814 | struct cgrp_cset_link *link; | |
2815 | ||
2816 | /* self is not affected by child_subsys_mask change */ | |
2817 | if (css->cgroup == cgrp) | |
2818 | continue; | |
2819 | ||
2820 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) | |
2821 | cgroup_migrate_add_src(link->cset, cgrp, | |
2822 | &preloaded_csets); | |
2823 | } | |
2824 | up_read(&css_set_rwsem); | |
2825 | ||
2826 | /* NULL dst indicates self on default hierarchy */ | |
2827 | ret = cgroup_migrate_prepare_dst(NULL, &preloaded_csets); | |
2828 | if (ret) | |
2829 | goto out_finish; | |
2830 | ||
10265075 | 2831 | down_write(&css_set_rwsem); |
f8f22e53 | 2832 | list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) { |
10265075 | 2833 | struct task_struct *task, *ntask; |
f8f22e53 TH |
2834 | |
2835 | /* src_csets precede dst_csets, break on the first dst_cset */ | |
2836 | if (!src_cset->mg_src_cgrp) | |
2837 | break; | |
2838 | ||
10265075 TH |
2839 | /* all tasks in src_csets need to be migrated */ |
2840 | list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list) | |
2841 | cgroup_taskset_add(task, &tset); | |
f8f22e53 | 2842 | } |
10265075 | 2843 | up_write(&css_set_rwsem); |
f8f22e53 | 2844 | |
10265075 | 2845 | ret = cgroup_taskset_migrate(&tset, cgrp); |
f8f22e53 TH |
2846 | out_finish: |
2847 | cgroup_migrate_finish(&preloaded_csets); | |
3014dde7 | 2848 | percpu_up_write(&cgroup_threadgroup_rwsem); |
f8f22e53 TH |
2849 | return ret; |
2850 | } | |
2851 | ||
2852 | /* change the enabled child controllers for a cgroup in the default hierarchy */ | |
451af504 TH |
2853 | static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, |
2854 | char *buf, size_t nbytes, | |
2855 | loff_t off) | |
f8f22e53 | 2856 | { |
8ab456ac AS |
2857 | unsigned long enable = 0, disable = 0; |
2858 | unsigned long css_enable, css_disable, old_sc, new_sc, old_ss, new_ss; | |
a9746d8d | 2859 | struct cgroup *cgrp, *child; |
f8f22e53 | 2860 | struct cgroup_subsys *ss; |
451af504 | 2861 | char *tok; |
f8f22e53 TH |
2862 | int ssid, ret; |
2863 | ||
2864 | /* | |
d37167ab TH |
2865 | * Parse input - space separated list of subsystem names prefixed |
2866 | * with either + or -. | |
f8f22e53 | 2867 | */ |
451af504 TH |
2868 | buf = strstrip(buf); |
2869 | while ((tok = strsep(&buf, " "))) { | |
a966a4ed AS |
2870 | unsigned long tmp_ss_mask = ~cgrp_dfl_root_inhibit_ss_mask; |
2871 | ||
d37167ab TH |
2872 | if (tok[0] == '\0') |
2873 | continue; | |
a966a4ed | 2874 | for_each_subsys_which(ss, ssid, &tmp_ss_mask) { |
fc5ed1e9 TH |
2875 | if (!cgroup_ssid_enabled(ssid) || |
2876 | strcmp(tok + 1, ss->name)) | |
f8f22e53 TH |
2877 | continue; |
2878 | ||
2879 | if (*tok == '+') { | |
7d331fa9 TH |
2880 | enable |= 1 << ssid; |
2881 | disable &= ~(1 << ssid); | |
f8f22e53 | 2882 | } else if (*tok == '-') { |
7d331fa9 TH |
2883 | disable |= 1 << ssid; |
2884 | enable &= ~(1 << ssid); | |
f8f22e53 TH |
2885 | } else { |
2886 | return -EINVAL; | |
2887 | } | |
2888 | break; | |
2889 | } | |
2890 | if (ssid == CGROUP_SUBSYS_COUNT) | |
2891 | return -EINVAL; | |
2892 | } | |
2893 | ||
a9746d8d TH |
2894 | cgrp = cgroup_kn_lock_live(of->kn); |
2895 | if (!cgrp) | |
2896 | return -ENODEV; | |
f8f22e53 TH |
2897 | |
2898 | for_each_subsys(ss, ssid) { | |
2899 | if (enable & (1 << ssid)) { | |
667c2491 | 2900 | if (cgrp->subtree_control & (1 << ssid)) { |
f8f22e53 TH |
2901 | enable &= ~(1 << ssid); |
2902 | continue; | |
2903 | } | |
2904 | ||
c29adf24 TH |
2905 | /* unavailable or not enabled on the parent? */ |
2906 | if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) || | |
2907 | (cgroup_parent(cgrp) && | |
667c2491 | 2908 | !(cgroup_parent(cgrp)->subtree_control & (1 << ssid)))) { |
c29adf24 TH |
2909 | ret = -ENOENT; |
2910 | goto out_unlock; | |
2911 | } | |
f8f22e53 | 2912 | } else if (disable & (1 << ssid)) { |
667c2491 | 2913 | if (!(cgrp->subtree_control & (1 << ssid))) { |
f8f22e53 TH |
2914 | disable &= ~(1 << ssid); |
2915 | continue; | |
2916 | } | |
2917 | ||
2918 | /* a child has it enabled? */ | |
2919 | cgroup_for_each_live_child(child, cgrp) { | |
667c2491 | 2920 | if (child->subtree_control & (1 << ssid)) { |
f8f22e53 | 2921 | ret = -EBUSY; |
ddab2b6e | 2922 | goto out_unlock; |
f8f22e53 TH |
2923 | } |
2924 | } | |
2925 | } | |
2926 | } | |
2927 | ||
2928 | if (!enable && !disable) { | |
2929 | ret = 0; | |
ddab2b6e | 2930 | goto out_unlock; |
f8f22e53 TH |
2931 | } |
2932 | ||
2933 | /* | |
667c2491 | 2934 | * Except for the root, subtree_control must be zero for a cgroup |
f8f22e53 TH |
2935 | * with tasks so that child cgroups don't compete against tasks. |
2936 | */ | |
d51f39b0 | 2937 | if (enable && cgroup_parent(cgrp) && !list_empty(&cgrp->cset_links)) { |
f8f22e53 TH |
2938 | ret = -EBUSY; |
2939 | goto out_unlock; | |
2940 | } | |
2941 | ||
2942 | /* | |
f63070d3 TH |
2943 | * Update subsys masks and calculate what needs to be done. More |
2944 | * subsystems than specified may need to be enabled or disabled | |
2945 | * depending on subsystem dependencies. | |
2946 | */ | |
755bf5ee TH |
2947 | old_sc = cgrp->subtree_control; |
2948 | old_ss = cgrp->child_subsys_mask; | |
2949 | new_sc = (old_sc | enable) & ~disable; | |
2950 | new_ss = cgroup_calc_child_subsys_mask(cgrp, new_sc); | |
f63070d3 | 2951 | |
755bf5ee TH |
2952 | css_enable = ~old_ss & new_ss; |
2953 | css_disable = old_ss & ~new_ss; | |
f63070d3 TH |
2954 | enable |= css_enable; |
2955 | disable |= css_disable; | |
c29adf24 | 2956 | |
db6e3053 TH |
2957 | /* |
2958 | * Because css offlining is asynchronous, userland might try to | |
2959 | * re-enable the same controller while the previous instance is | |
2960 | * still around. In such cases, wait till it's gone using | |
2961 | * offline_waitq. | |
2962 | */ | |
a966a4ed | 2963 | for_each_subsys_which(ss, ssid, &css_enable) { |
db6e3053 TH |
2964 | cgroup_for_each_live_child(child, cgrp) { |
2965 | DEFINE_WAIT(wait); | |
2966 | ||
2967 | if (!cgroup_css(child, ss)) | |
2968 | continue; | |
2969 | ||
2970 | cgroup_get(child); | |
2971 | prepare_to_wait(&child->offline_waitq, &wait, | |
2972 | TASK_UNINTERRUPTIBLE); | |
2973 | cgroup_kn_unlock(of->kn); | |
2974 | schedule(); | |
2975 | finish_wait(&child->offline_waitq, &wait); | |
2976 | cgroup_put(child); | |
2977 | ||
2978 | return restart_syscall(); | |
2979 | } | |
2980 | } | |
2981 | ||
755bf5ee TH |
2982 | cgrp->subtree_control = new_sc; |
2983 | cgrp->child_subsys_mask = new_ss; | |
2984 | ||
f63070d3 TH |
2985 | /* |
2986 | * Create new csses or make the existing ones visible. A css is | |
2987 | * created invisible if it's being implicitly enabled through | |
2988 | * dependency. An invisible css is made visible when the userland | |
2989 | * explicitly enables it. | |
f8f22e53 TH |
2990 | */ |
2991 | for_each_subsys(ss, ssid) { | |
2992 | if (!(enable & (1 << ssid))) | |
2993 | continue; | |
2994 | ||
2995 | cgroup_for_each_live_child(child, cgrp) { | |
f63070d3 TH |
2996 | if (css_enable & (1 << ssid)) |
2997 | ret = create_css(child, ss, | |
2998 | cgrp->subtree_control & (1 << ssid)); | |
2999 | else | |
4df8dc90 TH |
3000 | ret = css_populate_dir(cgroup_css(child, ss), |
3001 | NULL); | |
f8f22e53 TH |
3002 | if (ret) |
3003 | goto err_undo_css; | |
3004 | } | |
3005 | } | |
3006 | ||
c29adf24 TH |
3007 | /* |
3008 | * At this point, cgroup_e_css() results reflect the new csses | |
3009 | * making the following cgroup_update_dfl_csses() properly update | |
3010 | * css associations of all tasks in the subtree. | |
3011 | */ | |
f8f22e53 TH |
3012 | ret = cgroup_update_dfl_csses(cgrp); |
3013 | if (ret) | |
3014 | goto err_undo_css; | |
3015 | ||
f63070d3 TH |
3016 | /* |
3017 | * All tasks are migrated out of disabled csses. Kill or hide | |
3018 | * them. A css is hidden when the userland requests it to be | |
b4536f0c TH |
3019 | * disabled while other subsystems are still depending on it. The |
3020 | * css must not actively control resources and be in the vanilla | |
3021 | * state if it's made visible again later. Controllers which may | |
3022 | * be depended upon should provide ->css_reset() for this purpose. | |
f63070d3 | 3023 | */ |
f8f22e53 TH |
3024 | for_each_subsys(ss, ssid) { |
3025 | if (!(disable & (1 << ssid))) | |
3026 | continue; | |
3027 | ||
f63070d3 | 3028 | cgroup_for_each_live_child(child, cgrp) { |
b4536f0c TH |
3029 | struct cgroup_subsys_state *css = cgroup_css(child, ss); |
3030 | ||
3031 | if (css_disable & (1 << ssid)) { | |
3032 | kill_css(css); | |
3033 | } else { | |
4df8dc90 | 3034 | css_clear_dir(css, NULL); |
b4536f0c TH |
3035 | if (ss->css_reset) |
3036 | ss->css_reset(css); | |
3037 | } | |
f63070d3 | 3038 | } |
f8f22e53 TH |
3039 | } |
3040 | ||
56c807ba TH |
3041 | /* |
3042 | * The effective csses of all the descendants (excluding @cgrp) may | |
3043 | * have changed. Subsystems can optionally subscribe to this event | |
3044 | * by implementing ->css_e_css_changed() which is invoked if any of | |
3045 | * the effective csses seen from the css's cgroup may have changed. | |
3046 | */ | |
3047 | for_each_subsys(ss, ssid) { | |
3048 | struct cgroup_subsys_state *this_css = cgroup_css(cgrp, ss); | |
3049 | struct cgroup_subsys_state *css; | |
3050 | ||
3051 | if (!ss->css_e_css_changed || !this_css) | |
3052 | continue; | |
3053 | ||
3054 | css_for_each_descendant_pre(css, this_css) | |
3055 | if (css != this_css) | |
3056 | ss->css_e_css_changed(css); | |
3057 | } | |
3058 | ||
f8f22e53 TH |
3059 | kernfs_activate(cgrp->kn); |
3060 | ret = 0; | |
3061 | out_unlock: | |
a9746d8d | 3062 | cgroup_kn_unlock(of->kn); |
451af504 | 3063 | return ret ?: nbytes; |
f8f22e53 TH |
3064 | |
3065 | err_undo_css: | |
755bf5ee TH |
3066 | cgrp->subtree_control = old_sc; |
3067 | cgrp->child_subsys_mask = old_ss; | |
f8f22e53 TH |
3068 | |
3069 | for_each_subsys(ss, ssid) { | |
3070 | if (!(enable & (1 << ssid))) | |
3071 | continue; | |
3072 | ||
3073 | cgroup_for_each_live_child(child, cgrp) { | |
3074 | struct cgroup_subsys_state *css = cgroup_css(child, ss); | |
f63070d3 TH |
3075 | |
3076 | if (!css) | |
3077 | continue; | |
3078 | ||
3079 | if (css_enable & (1 << ssid)) | |
f8f22e53 | 3080 | kill_css(css); |
f63070d3 | 3081 | else |
4df8dc90 | 3082 | css_clear_dir(css, NULL); |
f8f22e53 TH |
3083 | } |
3084 | } | |
3085 | goto out_unlock; | |
3086 | } | |
3087 | ||
4a07c222 | 3088 | static int cgroup_events_show(struct seq_file *seq, void *v) |
842b597e | 3089 | { |
4a07c222 TH |
3090 | seq_printf(seq, "populated %d\n", |
3091 | (bool)seq_css(seq)->cgroup->populated_cnt); | |
842b597e TH |
3092 | return 0; |
3093 | } | |
3094 | ||
2bd59d48 TH |
3095 | static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
3096 | size_t nbytes, loff_t off) | |
355e0c48 | 3097 | { |
2bd59d48 TH |
3098 | struct cgroup *cgrp = of->kn->parent->priv; |
3099 | struct cftype *cft = of->kn->priv; | |
3100 | struct cgroup_subsys_state *css; | |
a742c59d | 3101 | int ret; |
355e0c48 | 3102 | |
b4168640 TH |
3103 | if (cft->write) |
3104 | return cft->write(of, buf, nbytes, off); | |
3105 | ||
2bd59d48 TH |
3106 | /* |
3107 | * kernfs guarantees that a file isn't deleted with operations in | |
3108 | * flight, which means that the matching css is and stays alive and | |
3109 | * doesn't need to be pinned. The RCU locking is not necessary | |
3110 | * either. It's just for the convenience of using cgroup_css(). | |
3111 | */ | |
3112 | rcu_read_lock(); | |
3113 | css = cgroup_css(cgrp, cft->ss); | |
3114 | rcu_read_unlock(); | |
a742c59d | 3115 | |
451af504 | 3116 | if (cft->write_u64) { |
a742c59d TH |
3117 | unsigned long long v; |
3118 | ret = kstrtoull(buf, 0, &v); | |
3119 | if (!ret) | |
3120 | ret = cft->write_u64(css, cft, v); | |
3121 | } else if (cft->write_s64) { | |
3122 | long long v; | |
3123 | ret = kstrtoll(buf, 0, &v); | |
3124 | if (!ret) | |
3125 | ret = cft->write_s64(css, cft, v); | |
e73d2c61 | 3126 | } else { |
a742c59d | 3127 | ret = -EINVAL; |
e73d2c61 | 3128 | } |
2bd59d48 | 3129 | |
a742c59d | 3130 | return ret ?: nbytes; |
355e0c48 PM |
3131 | } |
3132 | ||
6612f05b | 3133 | static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) |
db3b1497 | 3134 | { |
2bd59d48 | 3135 | return seq_cft(seq)->seq_start(seq, ppos); |
db3b1497 PM |
3136 | } |
3137 | ||
6612f05b | 3138 | static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) |
ddbcc7e8 | 3139 | { |
2bd59d48 | 3140 | return seq_cft(seq)->seq_next(seq, v, ppos); |
ddbcc7e8 PM |
3141 | } |
3142 | ||
6612f05b | 3143 | static void cgroup_seqfile_stop(struct seq_file *seq, void *v) |
ddbcc7e8 | 3144 | { |
2bd59d48 | 3145 | seq_cft(seq)->seq_stop(seq, v); |
ddbcc7e8 PM |
3146 | } |
3147 | ||
91796569 | 3148 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
e73d2c61 | 3149 | { |
7da11279 TH |
3150 | struct cftype *cft = seq_cft(m); |
3151 | struct cgroup_subsys_state *css = seq_css(m); | |
e73d2c61 | 3152 | |
2da8ca82 TH |
3153 | if (cft->seq_show) |
3154 | return cft->seq_show(m, arg); | |
e73d2c61 | 3155 | |
f4c753b7 | 3156 | if (cft->read_u64) |
896f5199 TH |
3157 | seq_printf(m, "%llu\n", cft->read_u64(css, cft)); |
3158 | else if (cft->read_s64) | |
3159 | seq_printf(m, "%lld\n", cft->read_s64(css, cft)); | |
3160 | else | |
3161 | return -EINVAL; | |
3162 | return 0; | |
91796569 PM |
3163 | } |
3164 | ||
2bd59d48 TH |
3165 | static struct kernfs_ops cgroup_kf_single_ops = { |
3166 | .atomic_write_len = PAGE_SIZE, | |
3167 | .write = cgroup_file_write, | |
3168 | .seq_show = cgroup_seqfile_show, | |
91796569 PM |
3169 | }; |
3170 | ||
2bd59d48 TH |
3171 | static struct kernfs_ops cgroup_kf_ops = { |
3172 | .atomic_write_len = PAGE_SIZE, | |
3173 | .write = cgroup_file_write, | |
3174 | .seq_start = cgroup_seqfile_start, | |
3175 | .seq_next = cgroup_seqfile_next, | |
3176 | .seq_stop = cgroup_seqfile_stop, | |
3177 | .seq_show = cgroup_seqfile_show, | |
3178 | }; | |
ddbcc7e8 PM |
3179 | |
3180 | /* | |
3181 | * cgroup_rename - Only allow simple rename of directories in place. | |
3182 | */ | |
2bd59d48 TH |
3183 | static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
3184 | const char *new_name_str) | |
ddbcc7e8 | 3185 | { |
2bd59d48 | 3186 | struct cgroup *cgrp = kn->priv; |
65dff759 | 3187 | int ret; |
65dff759 | 3188 | |
2bd59d48 | 3189 | if (kernfs_type(kn) != KERNFS_DIR) |
ddbcc7e8 | 3190 | return -ENOTDIR; |
2bd59d48 | 3191 | if (kn->parent != new_parent) |
ddbcc7e8 | 3192 | return -EIO; |
65dff759 | 3193 | |
6db8e85c TH |
3194 | /* |
3195 | * This isn't a proper migration and its usefulness is very | |
aa6ec29b | 3196 | * limited. Disallow on the default hierarchy. |
6db8e85c | 3197 | */ |
aa6ec29b | 3198 | if (cgroup_on_dfl(cgrp)) |
6db8e85c | 3199 | return -EPERM; |
099fca32 | 3200 | |
e1b2dc17 | 3201 | /* |
8353da1f | 3202 | * We're gonna grab cgroup_mutex which nests outside kernfs |
e1b2dc17 | 3203 | * active_ref. kernfs_rename() doesn't require active_ref |
8353da1f | 3204 | * protection. Break them before grabbing cgroup_mutex. |
e1b2dc17 TH |
3205 | */ |
3206 | kernfs_break_active_protection(new_parent); | |
3207 | kernfs_break_active_protection(kn); | |
099fca32 | 3208 | |
2bd59d48 | 3209 | mutex_lock(&cgroup_mutex); |
099fca32 | 3210 | |
2bd59d48 | 3211 | ret = kernfs_rename(kn, new_parent, new_name_str); |
099fca32 | 3212 | |
2bd59d48 | 3213 | mutex_unlock(&cgroup_mutex); |
e1b2dc17 TH |
3214 | |
3215 | kernfs_unbreak_active_protection(kn); | |
3216 | kernfs_unbreak_active_protection(new_parent); | |
2bd59d48 | 3217 | return ret; |
099fca32 LZ |
3218 | } |
3219 | ||
49957f8e TH |
3220 | /* set uid and gid of cgroup dirs and files to that of the creator */ |
3221 | static int cgroup_kn_set_ugid(struct kernfs_node *kn) | |
3222 | { | |
3223 | struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID, | |
3224 | .ia_uid = current_fsuid(), | |
3225 | .ia_gid = current_fsgid(), }; | |
3226 | ||
3227 | if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) && | |
3228 | gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID)) | |
3229 | return 0; | |
3230 | ||
3231 | return kernfs_setattr(kn, &iattr); | |
3232 | } | |
3233 | ||
4df8dc90 TH |
3234 | static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp, |
3235 | struct cftype *cft) | |
ddbcc7e8 | 3236 | { |
8d7e6fb0 | 3237 | char name[CGROUP_FILE_NAME_MAX]; |
2bd59d48 TH |
3238 | struct kernfs_node *kn; |
3239 | struct lock_class_key *key = NULL; | |
49957f8e | 3240 | int ret; |
05ef1d7c | 3241 | |
2bd59d48 TH |
3242 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
3243 | key = &cft->lockdep_key; | |
3244 | #endif | |
3245 | kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), | |
3246 | cgroup_file_mode(cft), 0, cft->kf_ops, cft, | |
dfeb0750 | 3247 | NULL, key); |
49957f8e TH |
3248 | if (IS_ERR(kn)) |
3249 | return PTR_ERR(kn); | |
3250 | ||
3251 | ret = cgroup_kn_set_ugid(kn); | |
f8f22e53 | 3252 | if (ret) { |
49957f8e | 3253 | kernfs_remove(kn); |
f8f22e53 TH |
3254 | return ret; |
3255 | } | |
3256 | ||
6f60eade TH |
3257 | if (cft->file_offset) { |
3258 | struct cgroup_file *cfile = (void *)css + cft->file_offset; | |
3259 | ||
3260 | kernfs_get(kn); | |
3261 | cfile->kn = kn; | |
3262 | list_add(&cfile->node, &css->files); | |
3263 | } | |
3264 | ||
f8f22e53 | 3265 | return 0; |
ddbcc7e8 PM |
3266 | } |
3267 | ||
b1f28d31 TH |
3268 | /** |
3269 | * cgroup_addrm_files - add or remove files to a cgroup directory | |
4df8dc90 TH |
3270 | * @css: the target css |
3271 | * @cgrp: the target cgroup (usually css->cgroup) | |
b1f28d31 TH |
3272 | * @cfts: array of cftypes to be added |
3273 | * @is_add: whether to add or remove | |
3274 | * | |
3275 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp. | |
6732ed85 | 3276 | * For removals, this function never fails. |
b1f28d31 | 3277 | */ |
4df8dc90 TH |
3278 | static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
3279 | struct cgroup *cgrp, struct cftype cfts[], | |
2bb566cb | 3280 | bool is_add) |
ddbcc7e8 | 3281 | { |
6732ed85 | 3282 | struct cftype *cft, *cft_end = NULL; |
b1f28d31 TH |
3283 | int ret; |
3284 | ||
01f6474c | 3285 | lockdep_assert_held(&cgroup_mutex); |
db0416b6 | 3286 | |
6732ed85 TH |
3287 | restart: |
3288 | for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 3289 | /* does cft->flags tell us to skip this file on @cgrp? */ |
05ebb6e6 | 3290 | if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp)) |
8cbbf2c9 | 3291 | continue; |
05ebb6e6 | 3292 | if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp)) |
873fe09e | 3293 | continue; |
d51f39b0 | 3294 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp)) |
f33fddc2 | 3295 | continue; |
d51f39b0 | 3296 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp)) |
f33fddc2 G |
3297 | continue; |
3298 | ||
2739d3cc | 3299 | if (is_add) { |
4df8dc90 | 3300 | ret = cgroup_add_file(css, cgrp, cft); |
b1f28d31 | 3301 | if (ret) { |
ed3d261b JP |
3302 | pr_warn("%s: failed to add %s, err=%d\n", |
3303 | __func__, cft->name, ret); | |
6732ed85 TH |
3304 | cft_end = cft; |
3305 | is_add = false; | |
3306 | goto restart; | |
b1f28d31 | 3307 | } |
2739d3cc LZ |
3308 | } else { |
3309 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 3310 | } |
ddbcc7e8 | 3311 | } |
b1f28d31 | 3312 | return 0; |
ddbcc7e8 PM |
3313 | } |
3314 | ||
21a2d343 | 3315 | static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) |
8e3f6541 TH |
3316 | { |
3317 | LIST_HEAD(pending); | |
2bb566cb | 3318 | struct cgroup_subsys *ss = cfts[0].ss; |
3dd06ffa | 3319 | struct cgroup *root = &ss->root->cgrp; |
492eb21b | 3320 | struct cgroup_subsys_state *css; |
9ccece80 | 3321 | int ret = 0; |
8e3f6541 | 3322 | |
01f6474c | 3323 | lockdep_assert_held(&cgroup_mutex); |
e8c82d20 | 3324 | |
e8c82d20 | 3325 | /* add/rm files for all cgroups created before */ |
ca8bdcaf | 3326 | css_for_each_descendant_pre(css, cgroup_css(root, ss)) { |
492eb21b TH |
3327 | struct cgroup *cgrp = css->cgroup; |
3328 | ||
e8c82d20 LZ |
3329 | if (cgroup_is_dead(cgrp)) |
3330 | continue; | |
3331 | ||
4df8dc90 | 3332 | ret = cgroup_addrm_files(css, cgrp, cfts, is_add); |
9ccece80 TH |
3333 | if (ret) |
3334 | break; | |
8e3f6541 | 3335 | } |
21a2d343 TH |
3336 | |
3337 | if (is_add && !ret) | |
3338 | kernfs_activate(root->kn); | |
9ccece80 | 3339 | return ret; |
8e3f6541 TH |
3340 | } |
3341 | ||
2da440a2 | 3342 | static void cgroup_exit_cftypes(struct cftype *cfts) |
8e3f6541 | 3343 | { |
2bb566cb | 3344 | struct cftype *cft; |
8e3f6541 | 3345 | |
2bd59d48 TH |
3346 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
3347 | /* free copy for custom atomic_write_len, see init_cftypes() */ | |
3348 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) | |
3349 | kfree(cft->kf_ops); | |
3350 | cft->kf_ops = NULL; | |
2da440a2 | 3351 | cft->ss = NULL; |
a8ddc821 TH |
3352 | |
3353 | /* revert flags set by cgroup core while adding @cfts */ | |
05ebb6e6 | 3354 | cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL); |
2bd59d48 | 3355 | } |
2da440a2 TH |
3356 | } |
3357 | ||
2bd59d48 | 3358 | static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
2da440a2 TH |
3359 | { |
3360 | struct cftype *cft; | |
3361 | ||
2bd59d48 TH |
3362 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
3363 | struct kernfs_ops *kf_ops; | |
3364 | ||
0adb0704 TH |
3365 | WARN_ON(cft->ss || cft->kf_ops); |
3366 | ||
2bd59d48 TH |
3367 | if (cft->seq_start) |
3368 | kf_ops = &cgroup_kf_ops; | |
3369 | else | |
3370 | kf_ops = &cgroup_kf_single_ops; | |
3371 | ||
3372 | /* | |
3373 | * Ugh... if @cft wants a custom max_write_len, we need to | |
3374 | * make a copy of kf_ops to set its atomic_write_len. | |
3375 | */ | |
3376 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { | |
3377 | kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); | |
3378 | if (!kf_ops) { | |
3379 | cgroup_exit_cftypes(cfts); | |
3380 | return -ENOMEM; | |
3381 | } | |
3382 | kf_ops->atomic_write_len = cft->max_write_len; | |
3383 | } | |
8e3f6541 | 3384 | |
2bd59d48 | 3385 | cft->kf_ops = kf_ops; |
2bb566cb | 3386 | cft->ss = ss; |
2bd59d48 | 3387 | } |
2bb566cb | 3388 | |
2bd59d48 | 3389 | return 0; |
2da440a2 TH |
3390 | } |
3391 | ||
21a2d343 TH |
3392 | static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
3393 | { | |
01f6474c | 3394 | lockdep_assert_held(&cgroup_mutex); |
21a2d343 TH |
3395 | |
3396 | if (!cfts || !cfts[0].ss) | |
3397 | return -ENOENT; | |
3398 | ||
3399 | list_del(&cfts->node); | |
3400 | cgroup_apply_cftypes(cfts, false); | |
3401 | cgroup_exit_cftypes(cfts); | |
3402 | return 0; | |
8e3f6541 | 3403 | } |
8e3f6541 | 3404 | |
79578621 TH |
3405 | /** |
3406 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
79578621 TH |
3407 | * @cfts: zero-length name terminated array of cftypes |
3408 | * | |
2bb566cb TH |
3409 | * Unregister @cfts. Files described by @cfts are removed from all |
3410 | * existing cgroups and all future cgroups won't have them either. This | |
3411 | * function can be called anytime whether @cfts' subsys is attached or not. | |
79578621 TH |
3412 | * |
3413 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2bb566cb | 3414 | * registered. |
79578621 | 3415 | */ |
2bb566cb | 3416 | int cgroup_rm_cftypes(struct cftype *cfts) |
79578621 | 3417 | { |
21a2d343 | 3418 | int ret; |
79578621 | 3419 | |
01f6474c | 3420 | mutex_lock(&cgroup_mutex); |
21a2d343 | 3421 | ret = cgroup_rm_cftypes_locked(cfts); |
01f6474c | 3422 | mutex_unlock(&cgroup_mutex); |
21a2d343 | 3423 | return ret; |
80b13586 TH |
3424 | } |
3425 | ||
8e3f6541 TH |
3426 | /** |
3427 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
3428 | * @ss: target cgroup subsystem | |
3429 | * @cfts: zero-length name terminated array of cftypes | |
3430 | * | |
3431 | * Register @cfts to @ss. Files described by @cfts are created for all | |
3432 | * existing cgroups to which @ss is attached and all future cgroups will | |
3433 | * have them too. This function can be called anytime whether @ss is | |
3434 | * attached or not. | |
3435 | * | |
3436 | * Returns 0 on successful registration, -errno on failure. Note that this | |
3437 | * function currently returns 0 as long as @cfts registration is successful | |
3438 | * even if some file creation attempts on existing cgroups fail. | |
3439 | */ | |
2cf669a5 | 3440 | static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 | 3441 | { |
9ccece80 | 3442 | int ret; |
8e3f6541 | 3443 | |
fc5ed1e9 | 3444 | if (!cgroup_ssid_enabled(ss->id)) |
c731ae1d LZ |
3445 | return 0; |
3446 | ||
dc5736ed LZ |
3447 | if (!cfts || cfts[0].name[0] == '\0') |
3448 | return 0; | |
2bb566cb | 3449 | |
2bd59d48 TH |
3450 | ret = cgroup_init_cftypes(ss, cfts); |
3451 | if (ret) | |
3452 | return ret; | |
79578621 | 3453 | |
01f6474c | 3454 | mutex_lock(&cgroup_mutex); |
21a2d343 | 3455 | |
0adb0704 | 3456 | list_add_tail(&cfts->node, &ss->cfts); |
21a2d343 | 3457 | ret = cgroup_apply_cftypes(cfts, true); |
9ccece80 | 3458 | if (ret) |
21a2d343 | 3459 | cgroup_rm_cftypes_locked(cfts); |
79578621 | 3460 | |
01f6474c | 3461 | mutex_unlock(&cgroup_mutex); |
9ccece80 | 3462 | return ret; |
79578621 TH |
3463 | } |
3464 | ||
a8ddc821 TH |
3465 | /** |
3466 | * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy | |
3467 | * @ss: target cgroup subsystem | |
3468 | * @cfts: zero-length name terminated array of cftypes | |
3469 | * | |
3470 | * Similar to cgroup_add_cftypes() but the added files are only used for | |
3471 | * the default hierarchy. | |
3472 | */ | |
3473 | int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) | |
3474 | { | |
3475 | struct cftype *cft; | |
3476 | ||
3477 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++) | |
05ebb6e6 | 3478 | cft->flags |= __CFTYPE_ONLY_ON_DFL; |
a8ddc821 TH |
3479 | return cgroup_add_cftypes(ss, cfts); |
3480 | } | |
3481 | ||
3482 | /** | |
3483 | * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies | |
3484 | * @ss: target cgroup subsystem | |
3485 | * @cfts: zero-length name terminated array of cftypes | |
3486 | * | |
3487 | * Similar to cgroup_add_cftypes() but the added files are only used for | |
3488 | * the legacy hierarchies. | |
3489 | */ | |
2cf669a5 TH |
3490 | int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
3491 | { | |
a8ddc821 TH |
3492 | struct cftype *cft; |
3493 | ||
fa8137be VG |
3494 | /* |
3495 | * If legacy_flies_on_dfl, we want to show the legacy files on the | |
3496 | * dfl hierarchy but iff the target subsystem hasn't been updated | |
3497 | * for the dfl hierarchy yet. | |
3498 | */ | |
3499 | if (!cgroup_legacy_files_on_dfl || | |
3500 | ss->dfl_cftypes != ss->legacy_cftypes) { | |
3501 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++) | |
3502 | cft->flags |= __CFTYPE_NOT_ON_DFL; | |
3503 | } | |
3504 | ||
2cf669a5 TH |
3505 | return cgroup_add_cftypes(ss, cfts); |
3506 | } | |
3507 | ||
a043e3b2 LZ |
3508 | /** |
3509 | * cgroup_task_count - count the number of tasks in a cgroup. | |
3510 | * @cgrp: the cgroup in question | |
3511 | * | |
3512 | * Return the number of tasks in the cgroup. | |
3513 | */ | |
07bc356e | 3514 | static int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
3515 | { |
3516 | int count = 0; | |
69d0206c | 3517 | struct cgrp_cset_link *link; |
817929ec | 3518 | |
96d365e0 | 3519 | down_read(&css_set_rwsem); |
69d0206c TH |
3520 | list_for_each_entry(link, &cgrp->cset_links, cset_link) |
3521 | count += atomic_read(&link->cset->refcount); | |
96d365e0 | 3522 | up_read(&css_set_rwsem); |
bbcb81d0 PM |
3523 | return count; |
3524 | } | |
3525 | ||
53fa5261 | 3526 | /** |
492eb21b | 3527 | * css_next_child - find the next child of a given css |
c2931b70 TH |
3528 | * @pos: the current position (%NULL to initiate traversal) |
3529 | * @parent: css whose children to walk | |
53fa5261 | 3530 | * |
c2931b70 | 3531 | * This function returns the next child of @parent and should be called |
87fb54f1 | 3532 | * under either cgroup_mutex or RCU read lock. The only requirement is |
c2931b70 TH |
3533 | * that @parent and @pos are accessible. The next sibling is guaranteed to |
3534 | * be returned regardless of their states. | |
3535 | * | |
3536 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3537 | * css which finished ->css_online() is guaranteed to be visible in the | |
3538 | * future iterations and will stay visible until the last reference is put. | |
3539 | * A css which hasn't finished ->css_online() or already finished | |
3540 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3541 | * responsibility to synchronize against on/offlining. | |
53fa5261 | 3542 | */ |
c2931b70 TH |
3543 | struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos, |
3544 | struct cgroup_subsys_state *parent) | |
53fa5261 | 3545 | { |
c2931b70 | 3546 | struct cgroup_subsys_state *next; |
53fa5261 | 3547 | |
8353da1f | 3548 | cgroup_assert_mutex_or_rcu_locked(); |
53fa5261 TH |
3549 | |
3550 | /* | |
de3f0341 TH |
3551 | * @pos could already have been unlinked from the sibling list. |
3552 | * Once a cgroup is removed, its ->sibling.next is no longer | |
3553 | * updated when its next sibling changes. CSS_RELEASED is set when | |
3554 | * @pos is taken off list, at which time its next pointer is valid, | |
3555 | * and, as releases are serialized, the one pointed to by the next | |
3556 | * pointer is guaranteed to not have started release yet. This | |
3557 | * implies that if we observe !CSS_RELEASED on @pos in this RCU | |
3558 | * critical section, the one pointed to by its next pointer is | |
3559 | * guaranteed to not have finished its RCU grace period even if we | |
3560 | * have dropped rcu_read_lock() inbetween iterations. | |
3b287a50 | 3561 | * |
de3f0341 TH |
3562 | * If @pos has CSS_RELEASED set, its next pointer can't be |
3563 | * dereferenced; however, as each css is given a monotonically | |
3564 | * increasing unique serial number and always appended to the | |
3565 | * sibling list, the next one can be found by walking the parent's | |
3566 | * children until the first css with higher serial number than | |
3567 | * @pos's. While this path can be slower, it happens iff iteration | |
3568 | * races against release and the race window is very small. | |
53fa5261 | 3569 | */ |
3b287a50 | 3570 | if (!pos) { |
c2931b70 TH |
3571 | next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling); |
3572 | } else if (likely(!(pos->flags & CSS_RELEASED))) { | |
3573 | next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling); | |
3b287a50 | 3574 | } else { |
c2931b70 | 3575 | list_for_each_entry_rcu(next, &parent->children, sibling) |
3b287a50 TH |
3576 | if (next->serial_nr > pos->serial_nr) |
3577 | break; | |
53fa5261 TH |
3578 | } |
3579 | ||
3b281afb TH |
3580 | /* |
3581 | * @next, if not pointing to the head, can be dereferenced and is | |
c2931b70 | 3582 | * the next sibling. |
3b281afb | 3583 | */ |
c2931b70 TH |
3584 | if (&next->sibling != &parent->children) |
3585 | return next; | |
3b281afb | 3586 | return NULL; |
53fa5261 | 3587 | } |
53fa5261 | 3588 | |
574bd9f7 | 3589 | /** |
492eb21b | 3590 | * css_next_descendant_pre - find the next descendant for pre-order walk |
574bd9f7 | 3591 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3592 | * @root: css whose descendants to walk |
574bd9f7 | 3593 | * |
492eb21b | 3594 | * To be used by css_for_each_descendant_pre(). Find the next descendant |
bd8815a6 TH |
3595 | * to visit for pre-order traversal of @root's descendants. @root is |
3596 | * included in the iteration and the first node to be visited. | |
75501a6d | 3597 | * |
87fb54f1 TH |
3598 | * While this function requires cgroup_mutex or RCU read locking, it |
3599 | * doesn't require the whole traversal to be contained in a single critical | |
3600 | * section. This function will return the correct next descendant as long | |
3601 | * as both @pos and @root are accessible and @pos is a descendant of @root. | |
c2931b70 TH |
3602 | * |
3603 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3604 | * css which finished ->css_online() is guaranteed to be visible in the | |
3605 | * future iterations and will stay visible until the last reference is put. | |
3606 | * A css which hasn't finished ->css_online() or already finished | |
3607 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3608 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 3609 | */ |
492eb21b TH |
3610 | struct cgroup_subsys_state * |
3611 | css_next_descendant_pre(struct cgroup_subsys_state *pos, | |
3612 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3613 | { |
492eb21b | 3614 | struct cgroup_subsys_state *next; |
574bd9f7 | 3615 | |
8353da1f | 3616 | cgroup_assert_mutex_or_rcu_locked(); |
574bd9f7 | 3617 | |
bd8815a6 | 3618 | /* if first iteration, visit @root */ |
7805d000 | 3619 | if (!pos) |
bd8815a6 | 3620 | return root; |
574bd9f7 TH |
3621 | |
3622 | /* visit the first child if exists */ | |
492eb21b | 3623 | next = css_next_child(NULL, pos); |
574bd9f7 TH |
3624 | if (next) |
3625 | return next; | |
3626 | ||
3627 | /* no child, visit my or the closest ancestor's next sibling */ | |
492eb21b | 3628 | while (pos != root) { |
5c9d535b | 3629 | next = css_next_child(pos, pos->parent); |
75501a6d | 3630 | if (next) |
574bd9f7 | 3631 | return next; |
5c9d535b | 3632 | pos = pos->parent; |
7805d000 | 3633 | } |
574bd9f7 TH |
3634 | |
3635 | return NULL; | |
3636 | } | |
574bd9f7 | 3637 | |
12a9d2fe | 3638 | /** |
492eb21b TH |
3639 | * css_rightmost_descendant - return the rightmost descendant of a css |
3640 | * @pos: css of interest | |
12a9d2fe | 3641 | * |
492eb21b TH |
3642 | * Return the rightmost descendant of @pos. If there's no descendant, @pos |
3643 | * is returned. This can be used during pre-order traversal to skip | |
12a9d2fe | 3644 | * subtree of @pos. |
75501a6d | 3645 | * |
87fb54f1 TH |
3646 | * While this function requires cgroup_mutex or RCU read locking, it |
3647 | * doesn't require the whole traversal to be contained in a single critical | |
3648 | * section. This function will return the correct rightmost descendant as | |
3649 | * long as @pos is accessible. | |
12a9d2fe | 3650 | */ |
492eb21b TH |
3651 | struct cgroup_subsys_state * |
3652 | css_rightmost_descendant(struct cgroup_subsys_state *pos) | |
12a9d2fe | 3653 | { |
492eb21b | 3654 | struct cgroup_subsys_state *last, *tmp; |
12a9d2fe | 3655 | |
8353da1f | 3656 | cgroup_assert_mutex_or_rcu_locked(); |
12a9d2fe TH |
3657 | |
3658 | do { | |
3659 | last = pos; | |
3660 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
3661 | pos = NULL; | |
492eb21b | 3662 | css_for_each_child(tmp, last) |
12a9d2fe TH |
3663 | pos = tmp; |
3664 | } while (pos); | |
3665 | ||
3666 | return last; | |
3667 | } | |
12a9d2fe | 3668 | |
492eb21b TH |
3669 | static struct cgroup_subsys_state * |
3670 | css_leftmost_descendant(struct cgroup_subsys_state *pos) | |
574bd9f7 | 3671 | { |
492eb21b | 3672 | struct cgroup_subsys_state *last; |
574bd9f7 TH |
3673 | |
3674 | do { | |
3675 | last = pos; | |
492eb21b | 3676 | pos = css_next_child(NULL, pos); |
574bd9f7 TH |
3677 | } while (pos); |
3678 | ||
3679 | return last; | |
3680 | } | |
3681 | ||
3682 | /** | |
492eb21b | 3683 | * css_next_descendant_post - find the next descendant for post-order walk |
574bd9f7 | 3684 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3685 | * @root: css whose descendants to walk |
574bd9f7 | 3686 | * |
492eb21b | 3687 | * To be used by css_for_each_descendant_post(). Find the next descendant |
bd8815a6 TH |
3688 | * to visit for post-order traversal of @root's descendants. @root is |
3689 | * included in the iteration and the last node to be visited. | |
75501a6d | 3690 | * |
87fb54f1 TH |
3691 | * While this function requires cgroup_mutex or RCU read locking, it |
3692 | * doesn't require the whole traversal to be contained in a single critical | |
3693 | * section. This function will return the correct next descendant as long | |
3694 | * as both @pos and @cgroup are accessible and @pos is a descendant of | |
3695 | * @cgroup. | |
c2931b70 TH |
3696 | * |
3697 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3698 | * css which finished ->css_online() is guaranteed to be visible in the | |
3699 | * future iterations and will stay visible until the last reference is put. | |
3700 | * A css which hasn't finished ->css_online() or already finished | |
3701 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3702 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 3703 | */ |
492eb21b TH |
3704 | struct cgroup_subsys_state * |
3705 | css_next_descendant_post(struct cgroup_subsys_state *pos, | |
3706 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3707 | { |
492eb21b | 3708 | struct cgroup_subsys_state *next; |
574bd9f7 | 3709 | |
8353da1f | 3710 | cgroup_assert_mutex_or_rcu_locked(); |
574bd9f7 | 3711 | |
58b79a91 TH |
3712 | /* if first iteration, visit leftmost descendant which may be @root */ |
3713 | if (!pos) | |
3714 | return css_leftmost_descendant(root); | |
574bd9f7 | 3715 | |
bd8815a6 TH |
3716 | /* if we visited @root, we're done */ |
3717 | if (pos == root) | |
3718 | return NULL; | |
3719 | ||
574bd9f7 | 3720 | /* if there's an unvisited sibling, visit its leftmost descendant */ |
5c9d535b | 3721 | next = css_next_child(pos, pos->parent); |
75501a6d | 3722 | if (next) |
492eb21b | 3723 | return css_leftmost_descendant(next); |
574bd9f7 TH |
3724 | |
3725 | /* no sibling left, visit parent */ | |
5c9d535b | 3726 | return pos->parent; |
574bd9f7 | 3727 | } |
574bd9f7 | 3728 | |
f3d46500 TH |
3729 | /** |
3730 | * css_has_online_children - does a css have online children | |
3731 | * @css: the target css | |
3732 | * | |
3733 | * Returns %true if @css has any online children; otherwise, %false. This | |
3734 | * function can be called from any context but the caller is responsible | |
3735 | * for synchronizing against on/offlining as necessary. | |
3736 | */ | |
3737 | bool css_has_online_children(struct cgroup_subsys_state *css) | |
cbc125ef | 3738 | { |
f3d46500 TH |
3739 | struct cgroup_subsys_state *child; |
3740 | bool ret = false; | |
cbc125ef TH |
3741 | |
3742 | rcu_read_lock(); | |
f3d46500 | 3743 | css_for_each_child(child, css) { |
99bae5f9 | 3744 | if (child->flags & CSS_ONLINE) { |
f3d46500 TH |
3745 | ret = true; |
3746 | break; | |
cbc125ef TH |
3747 | } |
3748 | } | |
3749 | rcu_read_unlock(); | |
f3d46500 | 3750 | return ret; |
574bd9f7 | 3751 | } |
574bd9f7 | 3752 | |
0942eeee | 3753 | /** |
72ec7029 | 3754 | * css_advance_task_iter - advance a task itererator to the next css_set |
0942eeee TH |
3755 | * @it: the iterator to advance |
3756 | * | |
3757 | * Advance @it to the next css_set to walk. | |
d515876e | 3758 | */ |
72ec7029 | 3759 | static void css_advance_task_iter(struct css_task_iter *it) |
d515876e | 3760 | { |
0f0a2b4f | 3761 | struct list_head *l = it->cset_pos; |
d515876e TH |
3762 | struct cgrp_cset_link *link; |
3763 | struct css_set *cset; | |
3764 | ||
3765 | /* Advance to the next non-empty css_set */ | |
3766 | do { | |
3767 | l = l->next; | |
0f0a2b4f TH |
3768 | if (l == it->cset_head) { |
3769 | it->cset_pos = NULL; | |
d515876e TH |
3770 | return; |
3771 | } | |
3ebb2b6e TH |
3772 | |
3773 | if (it->ss) { | |
3774 | cset = container_of(l, struct css_set, | |
3775 | e_cset_node[it->ss->id]); | |
3776 | } else { | |
3777 | link = list_entry(l, struct cgrp_cset_link, cset_link); | |
3778 | cset = link->cset; | |
3779 | } | |
c7561128 TH |
3780 | } while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks)); |
3781 | ||
0f0a2b4f | 3782 | it->cset_pos = l; |
c7561128 TH |
3783 | |
3784 | if (!list_empty(&cset->tasks)) | |
0f0a2b4f | 3785 | it->task_pos = cset->tasks.next; |
c7561128 | 3786 | else |
0f0a2b4f TH |
3787 | it->task_pos = cset->mg_tasks.next; |
3788 | ||
3789 | it->tasks_head = &cset->tasks; | |
3790 | it->mg_tasks_head = &cset->mg_tasks; | |
d515876e TH |
3791 | } |
3792 | ||
0942eeee | 3793 | /** |
72ec7029 TH |
3794 | * css_task_iter_start - initiate task iteration |
3795 | * @css: the css to walk tasks of | |
0942eeee TH |
3796 | * @it: the task iterator to use |
3797 | * | |
72ec7029 TH |
3798 | * Initiate iteration through the tasks of @css. The caller can call |
3799 | * css_task_iter_next() to walk through the tasks until the function | |
3800 | * returns NULL. On completion of iteration, css_task_iter_end() must be | |
3801 | * called. | |
0942eeee TH |
3802 | * |
3803 | * Note that this function acquires a lock which is released when the | |
3804 | * iteration finishes. The caller can't sleep while iteration is in | |
3805 | * progress. | |
3806 | */ | |
72ec7029 TH |
3807 | void css_task_iter_start(struct cgroup_subsys_state *css, |
3808 | struct css_task_iter *it) | |
96d365e0 | 3809 | __acquires(css_set_rwsem) |
817929ec | 3810 | { |
56fde9e0 TH |
3811 | /* no one should try to iterate before mounting cgroups */ |
3812 | WARN_ON_ONCE(!use_task_css_set_links); | |
31a7df01 | 3813 | |
96d365e0 | 3814 | down_read(&css_set_rwsem); |
c59cd3d8 | 3815 | |
3ebb2b6e TH |
3816 | it->ss = css->ss; |
3817 | ||
3818 | if (it->ss) | |
3819 | it->cset_pos = &css->cgroup->e_csets[css->ss->id]; | |
3820 | else | |
3821 | it->cset_pos = &css->cgroup->cset_links; | |
3822 | ||
0f0a2b4f | 3823 | it->cset_head = it->cset_pos; |
c59cd3d8 | 3824 | |
72ec7029 | 3825 | css_advance_task_iter(it); |
817929ec PM |
3826 | } |
3827 | ||
0942eeee | 3828 | /** |
72ec7029 | 3829 | * css_task_iter_next - return the next task for the iterator |
0942eeee TH |
3830 | * @it: the task iterator being iterated |
3831 | * | |
3832 | * The "next" function for task iteration. @it should have been | |
72ec7029 TH |
3833 | * initialized via css_task_iter_start(). Returns NULL when the iteration |
3834 | * reaches the end. | |
0942eeee | 3835 | */ |
72ec7029 | 3836 | struct task_struct *css_task_iter_next(struct css_task_iter *it) |
817929ec PM |
3837 | { |
3838 | struct task_struct *res; | |
0f0a2b4f | 3839 | struct list_head *l = it->task_pos; |
817929ec PM |
3840 | |
3841 | /* If the iterator cg is NULL, we have no tasks */ | |
0f0a2b4f | 3842 | if (!it->cset_pos) |
817929ec PM |
3843 | return NULL; |
3844 | res = list_entry(l, struct task_struct, cg_list); | |
c7561128 TH |
3845 | |
3846 | /* | |
3847 | * Advance iterator to find next entry. cset->tasks is consumed | |
3848 | * first and then ->mg_tasks. After ->mg_tasks, we move onto the | |
3849 | * next cset. | |
3850 | */ | |
817929ec | 3851 | l = l->next; |
c7561128 | 3852 | |
0f0a2b4f TH |
3853 | if (l == it->tasks_head) |
3854 | l = it->mg_tasks_head->next; | |
c7561128 | 3855 | |
0f0a2b4f | 3856 | if (l == it->mg_tasks_head) |
72ec7029 | 3857 | css_advance_task_iter(it); |
c7561128 | 3858 | else |
0f0a2b4f | 3859 | it->task_pos = l; |
c7561128 | 3860 | |
817929ec PM |
3861 | return res; |
3862 | } | |
3863 | ||
0942eeee | 3864 | /** |
72ec7029 | 3865 | * css_task_iter_end - finish task iteration |
0942eeee TH |
3866 | * @it: the task iterator to finish |
3867 | * | |
72ec7029 | 3868 | * Finish task iteration started by css_task_iter_start(). |
0942eeee | 3869 | */ |
72ec7029 | 3870 | void css_task_iter_end(struct css_task_iter *it) |
96d365e0 | 3871 | __releases(css_set_rwsem) |
31a7df01 | 3872 | { |
96d365e0 | 3873 | up_read(&css_set_rwsem); |
31a7df01 CW |
3874 | } |
3875 | ||
3876 | /** | |
8cc99345 TH |
3877 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another |
3878 | * @to: cgroup to which the tasks will be moved | |
3879 | * @from: cgroup in which the tasks currently reside | |
31a7df01 | 3880 | * |
eaf797ab TH |
3881 | * Locking rules between cgroup_post_fork() and the migration path |
3882 | * guarantee that, if a task is forking while being migrated, the new child | |
3883 | * is guaranteed to be either visible in the source cgroup after the | |
3884 | * parent's migration is complete or put into the target cgroup. No task | |
3885 | * can slip out of migration through forking. | |
31a7df01 | 3886 | */ |
8cc99345 | 3887 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) |
31a7df01 | 3888 | { |
952aaa12 TH |
3889 | LIST_HEAD(preloaded_csets); |
3890 | struct cgrp_cset_link *link; | |
72ec7029 | 3891 | struct css_task_iter it; |
e406d1cf | 3892 | struct task_struct *task; |
952aaa12 | 3893 | int ret; |
31a7df01 | 3894 | |
952aaa12 | 3895 | mutex_lock(&cgroup_mutex); |
31a7df01 | 3896 | |
952aaa12 TH |
3897 | /* all tasks in @from are being moved, all csets are source */ |
3898 | down_read(&css_set_rwsem); | |
3899 | list_for_each_entry(link, &from->cset_links, cset_link) | |
3900 | cgroup_migrate_add_src(link->cset, to, &preloaded_csets); | |
3901 | up_read(&css_set_rwsem); | |
31a7df01 | 3902 | |
952aaa12 TH |
3903 | ret = cgroup_migrate_prepare_dst(to, &preloaded_csets); |
3904 | if (ret) | |
3905 | goto out_err; | |
8cc99345 | 3906 | |
952aaa12 TH |
3907 | /* |
3908 | * Migrate tasks one-by-one until @form is empty. This fails iff | |
3909 | * ->can_attach() fails. | |
3910 | */ | |
e406d1cf | 3911 | do { |
9d800df1 | 3912 | css_task_iter_start(&from->self, &it); |
e406d1cf TH |
3913 | task = css_task_iter_next(&it); |
3914 | if (task) | |
3915 | get_task_struct(task); | |
3916 | css_task_iter_end(&it); | |
3917 | ||
3918 | if (task) { | |
9af2ec45 | 3919 | ret = cgroup_migrate(task, false, to); |
e406d1cf TH |
3920 | put_task_struct(task); |
3921 | } | |
3922 | } while (task && !ret); | |
952aaa12 TH |
3923 | out_err: |
3924 | cgroup_migrate_finish(&preloaded_csets); | |
47cfcd09 | 3925 | mutex_unlock(&cgroup_mutex); |
e406d1cf | 3926 | return ret; |
8cc99345 TH |
3927 | } |
3928 | ||
bbcb81d0 | 3929 | /* |
102a775e | 3930 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
3931 | * |
3932 | * Reading this file can return large amounts of data if a cgroup has | |
3933 | * *lots* of attached tasks. So it may need several calls to read(), | |
3934 | * but we cannot guarantee that the information we produce is correct | |
3935 | * unless we produce it entirely atomically. | |
3936 | * | |
bbcb81d0 | 3937 | */ |
bbcb81d0 | 3938 | |
24528255 LZ |
3939 | /* which pidlist file are we talking about? */ |
3940 | enum cgroup_filetype { | |
3941 | CGROUP_FILE_PROCS, | |
3942 | CGROUP_FILE_TASKS, | |
3943 | }; | |
3944 | ||
3945 | /* | |
3946 | * A pidlist is a list of pids that virtually represents the contents of one | |
3947 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
3948 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
3949 | * to the cgroup. | |
3950 | */ | |
3951 | struct cgroup_pidlist { | |
3952 | /* | |
3953 | * used to find which pidlist is wanted. doesn't change as long as | |
3954 | * this particular list stays in the list. | |
3955 | */ | |
3956 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
3957 | /* array of xids */ | |
3958 | pid_t *list; | |
3959 | /* how many elements the above list has */ | |
3960 | int length; | |
24528255 LZ |
3961 | /* each of these stored in a list by its cgroup */ |
3962 | struct list_head links; | |
3963 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
3964 | struct cgroup *owner; | |
b1a21367 TH |
3965 | /* for delayed destruction */ |
3966 | struct delayed_work destroy_dwork; | |
24528255 LZ |
3967 | }; |
3968 | ||
d1d9fd33 BB |
3969 | /* |
3970 | * The following two functions "fix" the issue where there are more pids | |
3971 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
3972 | * TODO: replace with a kernel-wide solution to this problem | |
3973 | */ | |
3974 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
3975 | static void *pidlist_allocate(int count) | |
3976 | { | |
3977 | if (PIDLIST_TOO_LARGE(count)) | |
3978 | return vmalloc(count * sizeof(pid_t)); | |
3979 | else | |
3980 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
3981 | } | |
b1a21367 | 3982 | |
d1d9fd33 BB |
3983 | static void pidlist_free(void *p) |
3984 | { | |
58794514 | 3985 | kvfree(p); |
d1d9fd33 | 3986 | } |
d1d9fd33 | 3987 | |
b1a21367 TH |
3988 | /* |
3989 | * Used to destroy all pidlists lingering waiting for destroy timer. None | |
3990 | * should be left afterwards. | |
3991 | */ | |
3992 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) | |
3993 | { | |
3994 | struct cgroup_pidlist *l, *tmp_l; | |
3995 | ||
3996 | mutex_lock(&cgrp->pidlist_mutex); | |
3997 | list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) | |
3998 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); | |
3999 | mutex_unlock(&cgrp->pidlist_mutex); | |
4000 | ||
4001 | flush_workqueue(cgroup_pidlist_destroy_wq); | |
4002 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
4003 | } | |
4004 | ||
4005 | static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) | |
4006 | { | |
4007 | struct delayed_work *dwork = to_delayed_work(work); | |
4008 | struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, | |
4009 | destroy_dwork); | |
4010 | struct cgroup_pidlist *tofree = NULL; | |
4011 | ||
4012 | mutex_lock(&l->owner->pidlist_mutex); | |
b1a21367 TH |
4013 | |
4014 | /* | |
04502365 TH |
4015 | * Destroy iff we didn't get queued again. The state won't change |
4016 | * as destroy_dwork can only be queued while locked. | |
b1a21367 | 4017 | */ |
04502365 | 4018 | if (!delayed_work_pending(dwork)) { |
b1a21367 TH |
4019 | list_del(&l->links); |
4020 | pidlist_free(l->list); | |
4021 | put_pid_ns(l->key.ns); | |
4022 | tofree = l; | |
4023 | } | |
4024 | ||
b1a21367 TH |
4025 | mutex_unlock(&l->owner->pidlist_mutex); |
4026 | kfree(tofree); | |
4027 | } | |
4028 | ||
bbcb81d0 | 4029 | /* |
102a775e | 4030 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 4031 | * Returns the number of unique elements. |
bbcb81d0 | 4032 | */ |
6ee211ad | 4033 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 4034 | { |
102a775e | 4035 | int src, dest = 1; |
102a775e BB |
4036 | |
4037 | /* | |
4038 | * we presume the 0th element is unique, so i starts at 1. trivial | |
4039 | * edge cases first; no work needs to be done for either | |
4040 | */ | |
4041 | if (length == 0 || length == 1) | |
4042 | return length; | |
4043 | /* src and dest walk down the list; dest counts unique elements */ | |
4044 | for (src = 1; src < length; src++) { | |
4045 | /* find next unique element */ | |
4046 | while (list[src] == list[src-1]) { | |
4047 | src++; | |
4048 | if (src == length) | |
4049 | goto after; | |
4050 | } | |
4051 | /* dest always points to where the next unique element goes */ | |
4052 | list[dest] = list[src]; | |
4053 | dest++; | |
4054 | } | |
4055 | after: | |
102a775e BB |
4056 | return dest; |
4057 | } | |
4058 | ||
afb2bc14 TH |
4059 | /* |
4060 | * The two pid files - task and cgroup.procs - guaranteed that the result | |
4061 | * is sorted, which forced this whole pidlist fiasco. As pid order is | |
4062 | * different per namespace, each namespace needs differently sorted list, | |
4063 | * making it impossible to use, for example, single rbtree of member tasks | |
4064 | * sorted by task pointer. As pidlists can be fairly large, allocating one | |
4065 | * per open file is dangerous, so cgroup had to implement shared pool of | |
4066 | * pidlists keyed by cgroup and namespace. | |
4067 | * | |
4068 | * All this extra complexity was caused by the original implementation | |
4069 | * committing to an entirely unnecessary property. In the long term, we | |
aa6ec29b TH |
4070 | * want to do away with it. Explicitly scramble sort order if on the |
4071 | * default hierarchy so that no such expectation exists in the new | |
4072 | * interface. | |
afb2bc14 TH |
4073 | * |
4074 | * Scrambling is done by swapping every two consecutive bits, which is | |
4075 | * non-identity one-to-one mapping which disturbs sort order sufficiently. | |
4076 | */ | |
4077 | static pid_t pid_fry(pid_t pid) | |
4078 | { | |
4079 | unsigned a = pid & 0x55555555; | |
4080 | unsigned b = pid & 0xAAAAAAAA; | |
4081 | ||
4082 | return (a << 1) | (b >> 1); | |
4083 | } | |
4084 | ||
4085 | static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) | |
4086 | { | |
aa6ec29b | 4087 | if (cgroup_on_dfl(cgrp)) |
afb2bc14 TH |
4088 | return pid_fry(pid); |
4089 | else | |
4090 | return pid; | |
4091 | } | |
4092 | ||
102a775e BB |
4093 | static int cmppid(const void *a, const void *b) |
4094 | { | |
4095 | return *(pid_t *)a - *(pid_t *)b; | |
4096 | } | |
4097 | ||
afb2bc14 TH |
4098 | static int fried_cmppid(const void *a, const void *b) |
4099 | { | |
4100 | return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); | |
4101 | } | |
4102 | ||
e6b81710 TH |
4103 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
4104 | enum cgroup_filetype type) | |
4105 | { | |
4106 | struct cgroup_pidlist *l; | |
4107 | /* don't need task_nsproxy() if we're looking at ourself */ | |
4108 | struct pid_namespace *ns = task_active_pid_ns(current); | |
4109 | ||
4110 | lockdep_assert_held(&cgrp->pidlist_mutex); | |
4111 | ||
4112 | list_for_each_entry(l, &cgrp->pidlists, links) | |
4113 | if (l->key.type == type && l->key.ns == ns) | |
4114 | return l; | |
4115 | return NULL; | |
4116 | } | |
4117 | ||
72a8cb30 BB |
4118 | /* |
4119 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
4120 | * returns with the lock on that pidlist already held, and takes care | |
4121 | * of the use count, or returns NULL with no locks held if we're out of | |
4122 | * memory. | |
4123 | */ | |
e6b81710 TH |
4124 | static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
4125 | enum cgroup_filetype type) | |
72a8cb30 BB |
4126 | { |
4127 | struct cgroup_pidlist *l; | |
b70cc5fd | 4128 | |
e6b81710 TH |
4129 | lockdep_assert_held(&cgrp->pidlist_mutex); |
4130 | ||
4131 | l = cgroup_pidlist_find(cgrp, type); | |
4132 | if (l) | |
4133 | return l; | |
4134 | ||
72a8cb30 | 4135 | /* entry not found; create a new one */ |
f4f4be2b | 4136 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
e6b81710 | 4137 | if (!l) |
72a8cb30 | 4138 | return l; |
e6b81710 | 4139 | |
b1a21367 | 4140 | INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
72a8cb30 | 4141 | l->key.type = type; |
e6b81710 TH |
4142 | /* don't need task_nsproxy() if we're looking at ourself */ |
4143 | l->key.ns = get_pid_ns(task_active_pid_ns(current)); | |
72a8cb30 BB |
4144 | l->owner = cgrp; |
4145 | list_add(&l->links, &cgrp->pidlists); | |
72a8cb30 BB |
4146 | return l; |
4147 | } | |
4148 | ||
102a775e BB |
4149 | /* |
4150 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
4151 | */ | |
72a8cb30 BB |
4152 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
4153 | struct cgroup_pidlist **lp) | |
102a775e BB |
4154 | { |
4155 | pid_t *array; | |
4156 | int length; | |
4157 | int pid, n = 0; /* used for populating the array */ | |
72ec7029 | 4158 | struct css_task_iter it; |
817929ec | 4159 | struct task_struct *tsk; |
102a775e BB |
4160 | struct cgroup_pidlist *l; |
4161 | ||
4bac00d1 TH |
4162 | lockdep_assert_held(&cgrp->pidlist_mutex); |
4163 | ||
102a775e BB |
4164 | /* |
4165 | * If cgroup gets more users after we read count, we won't have | |
4166 | * enough space - tough. This race is indistinguishable to the | |
4167 | * caller from the case that the additional cgroup users didn't | |
4168 | * show up until sometime later on. | |
4169 | */ | |
4170 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 4171 | array = pidlist_allocate(length); |
102a775e BB |
4172 | if (!array) |
4173 | return -ENOMEM; | |
4174 | /* now, populate the array */ | |
9d800df1 | 4175 | css_task_iter_start(&cgrp->self, &it); |
72ec7029 | 4176 | while ((tsk = css_task_iter_next(&it))) { |
102a775e | 4177 | if (unlikely(n == length)) |
817929ec | 4178 | break; |
102a775e | 4179 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
4180 | if (type == CGROUP_FILE_PROCS) |
4181 | pid = task_tgid_vnr(tsk); | |
4182 | else | |
4183 | pid = task_pid_vnr(tsk); | |
102a775e BB |
4184 | if (pid > 0) /* make sure to only use valid results */ |
4185 | array[n++] = pid; | |
817929ec | 4186 | } |
72ec7029 | 4187 | css_task_iter_end(&it); |
102a775e BB |
4188 | length = n; |
4189 | /* now sort & (if procs) strip out duplicates */ | |
aa6ec29b | 4190 | if (cgroup_on_dfl(cgrp)) |
afb2bc14 TH |
4191 | sort(array, length, sizeof(pid_t), fried_cmppid, NULL); |
4192 | else | |
4193 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 4194 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 4195 | length = pidlist_uniq(array, length); |
e6b81710 | 4196 | |
e6b81710 | 4197 | l = cgroup_pidlist_find_create(cgrp, type); |
72a8cb30 | 4198 | if (!l) { |
d1d9fd33 | 4199 | pidlist_free(array); |
72a8cb30 | 4200 | return -ENOMEM; |
102a775e | 4201 | } |
e6b81710 TH |
4202 | |
4203 | /* store array, freeing old if necessary */ | |
d1d9fd33 | 4204 | pidlist_free(l->list); |
102a775e BB |
4205 | l->list = array; |
4206 | l->length = length; | |
72a8cb30 | 4207 | *lp = l; |
102a775e | 4208 | return 0; |
bbcb81d0 PM |
4209 | } |
4210 | ||
846c7bb0 | 4211 | /** |
a043e3b2 | 4212 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
4213 | * @stats: cgroupstats to fill information into |
4214 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
4215 | * been requested. | |
a043e3b2 LZ |
4216 | * |
4217 | * Build and fill cgroupstats so that taskstats can export it to user | |
4218 | * space. | |
846c7bb0 BS |
4219 | */ |
4220 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
4221 | { | |
2bd59d48 | 4222 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
bd89aabc | 4223 | struct cgroup *cgrp; |
72ec7029 | 4224 | struct css_task_iter it; |
846c7bb0 | 4225 | struct task_struct *tsk; |
33d283be | 4226 | |
2bd59d48 TH |
4227 | /* it should be kernfs_node belonging to cgroupfs and is a directory */ |
4228 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || | |
4229 | kernfs_type(kn) != KERNFS_DIR) | |
4230 | return -EINVAL; | |
4231 | ||
bad34660 LZ |
4232 | mutex_lock(&cgroup_mutex); |
4233 | ||
846c7bb0 | 4234 | /* |
2bd59d48 | 4235 | * We aren't being called from kernfs and there's no guarantee on |
ec903c0c | 4236 | * @kn->priv's validity. For this and css_tryget_online_from_dir(), |
2bd59d48 | 4237 | * @kn->priv is RCU safe. Let's do the RCU dancing. |
846c7bb0 | 4238 | */ |
2bd59d48 TH |
4239 | rcu_read_lock(); |
4240 | cgrp = rcu_dereference(kn->priv); | |
bad34660 | 4241 | if (!cgrp || cgroup_is_dead(cgrp)) { |
2bd59d48 | 4242 | rcu_read_unlock(); |
bad34660 | 4243 | mutex_unlock(&cgroup_mutex); |
2bd59d48 TH |
4244 | return -ENOENT; |
4245 | } | |
bad34660 | 4246 | rcu_read_unlock(); |
846c7bb0 | 4247 | |
9d800df1 | 4248 | css_task_iter_start(&cgrp->self, &it); |
72ec7029 | 4249 | while ((tsk = css_task_iter_next(&it))) { |
846c7bb0 BS |
4250 | switch (tsk->state) { |
4251 | case TASK_RUNNING: | |
4252 | stats->nr_running++; | |
4253 | break; | |
4254 | case TASK_INTERRUPTIBLE: | |
4255 | stats->nr_sleeping++; | |
4256 | break; | |
4257 | case TASK_UNINTERRUPTIBLE: | |
4258 | stats->nr_uninterruptible++; | |
4259 | break; | |
4260 | case TASK_STOPPED: | |
4261 | stats->nr_stopped++; | |
4262 | break; | |
4263 | default: | |
4264 | if (delayacct_is_task_waiting_on_io(tsk)) | |
4265 | stats->nr_io_wait++; | |
4266 | break; | |
4267 | } | |
4268 | } | |
72ec7029 | 4269 | css_task_iter_end(&it); |
846c7bb0 | 4270 | |
bad34660 | 4271 | mutex_unlock(&cgroup_mutex); |
2bd59d48 | 4272 | return 0; |
846c7bb0 BS |
4273 | } |
4274 | ||
8f3ff208 | 4275 | |
bbcb81d0 | 4276 | /* |
102a775e | 4277 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 4278 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 4279 | * in the cgroup->l->list array. |
bbcb81d0 | 4280 | */ |
cc31edce | 4281 | |
102a775e | 4282 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 4283 | { |
cc31edce PM |
4284 | /* |
4285 | * Initially we receive a position value that corresponds to | |
4286 | * one more than the last pid shown (or 0 on the first call or | |
4287 | * after a seek to the start). Use a binary-search to find the | |
4288 | * next pid to display, if any | |
4289 | */ | |
2bd59d48 | 4290 | struct kernfs_open_file *of = s->private; |
7da11279 | 4291 | struct cgroup *cgrp = seq_css(s)->cgroup; |
4bac00d1 | 4292 | struct cgroup_pidlist *l; |
7da11279 | 4293 | enum cgroup_filetype type = seq_cft(s)->private; |
cc31edce | 4294 | int index = 0, pid = *pos; |
4bac00d1 TH |
4295 | int *iter, ret; |
4296 | ||
4297 | mutex_lock(&cgrp->pidlist_mutex); | |
4298 | ||
4299 | /* | |
5d22444f | 4300 | * !NULL @of->priv indicates that this isn't the first start() |
4bac00d1 | 4301 | * after open. If the matching pidlist is around, we can use that. |
5d22444f | 4302 | * Look for it. Note that @of->priv can't be used directly. It |
4bac00d1 TH |
4303 | * could already have been destroyed. |
4304 | */ | |
5d22444f TH |
4305 | if (of->priv) |
4306 | of->priv = cgroup_pidlist_find(cgrp, type); | |
4bac00d1 TH |
4307 | |
4308 | /* | |
4309 | * Either this is the first start() after open or the matching | |
4310 | * pidlist has been destroyed inbetween. Create a new one. | |
4311 | */ | |
5d22444f TH |
4312 | if (!of->priv) { |
4313 | ret = pidlist_array_load(cgrp, type, | |
4314 | (struct cgroup_pidlist **)&of->priv); | |
4bac00d1 TH |
4315 | if (ret) |
4316 | return ERR_PTR(ret); | |
4317 | } | |
5d22444f | 4318 | l = of->priv; |
cc31edce | 4319 | |
cc31edce | 4320 | if (pid) { |
102a775e | 4321 | int end = l->length; |
20777766 | 4322 | |
cc31edce PM |
4323 | while (index < end) { |
4324 | int mid = (index + end) / 2; | |
afb2bc14 | 4325 | if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { |
cc31edce PM |
4326 | index = mid; |
4327 | break; | |
afb2bc14 | 4328 | } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) |
cc31edce PM |
4329 | index = mid + 1; |
4330 | else | |
4331 | end = mid; | |
4332 | } | |
4333 | } | |
4334 | /* If we're off the end of the array, we're done */ | |
102a775e | 4335 | if (index >= l->length) |
cc31edce PM |
4336 | return NULL; |
4337 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 4338 | iter = l->list + index; |
afb2bc14 | 4339 | *pos = cgroup_pid_fry(cgrp, *iter); |
cc31edce PM |
4340 | return iter; |
4341 | } | |
4342 | ||
102a775e | 4343 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 4344 | { |
2bd59d48 | 4345 | struct kernfs_open_file *of = s->private; |
5d22444f | 4346 | struct cgroup_pidlist *l = of->priv; |
62236858 | 4347 | |
5d22444f TH |
4348 | if (l) |
4349 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, | |
04502365 | 4350 | CGROUP_PIDLIST_DESTROY_DELAY); |
7da11279 | 4351 | mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
cc31edce PM |
4352 | } |
4353 | ||
102a775e | 4354 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 4355 | { |
2bd59d48 | 4356 | struct kernfs_open_file *of = s->private; |
5d22444f | 4357 | struct cgroup_pidlist *l = of->priv; |
102a775e BB |
4358 | pid_t *p = v; |
4359 | pid_t *end = l->list + l->length; | |
cc31edce PM |
4360 | /* |
4361 | * Advance to the next pid in the array. If this goes off the | |
4362 | * end, we're done | |
4363 | */ | |
4364 | p++; | |
4365 | if (p >= end) { | |
4366 | return NULL; | |
4367 | } else { | |
7da11279 | 4368 | *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); |
cc31edce PM |
4369 | return p; |
4370 | } | |
4371 | } | |
4372 | ||
102a775e | 4373 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce | 4374 | { |
94ff212d JP |
4375 | seq_printf(s, "%d\n", *(int *)v); |
4376 | ||
4377 | return 0; | |
cc31edce | 4378 | } |
bbcb81d0 | 4379 | |
182446d0 TH |
4380 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
4381 | struct cftype *cft) | |
81a6a5cd | 4382 | { |
182446d0 | 4383 | return notify_on_release(css->cgroup); |
81a6a5cd PM |
4384 | } |
4385 | ||
182446d0 TH |
4386 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
4387 | struct cftype *cft, u64 val) | |
6379c106 | 4388 | { |
6379c106 | 4389 | if (val) |
182446d0 | 4390 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 | 4391 | else |
182446d0 | 4392 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 PM |
4393 | return 0; |
4394 | } | |
4395 | ||
182446d0 TH |
4396 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
4397 | struct cftype *cft) | |
97978e6d | 4398 | { |
182446d0 | 4399 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4400 | } |
4401 | ||
182446d0 TH |
4402 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
4403 | struct cftype *cft, u64 val) | |
97978e6d DL |
4404 | { |
4405 | if (val) | |
182446d0 | 4406 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d | 4407 | else |
182446d0 | 4408 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4409 | return 0; |
4410 | } | |
4411 | ||
a14c6874 TH |
4412 | /* cgroup core interface files for the default hierarchy */ |
4413 | static struct cftype cgroup_dfl_base_files[] = { | |
81a6a5cd | 4414 | { |
d5c56ced | 4415 | .name = "cgroup.procs", |
6f60eade | 4416 | .file_offset = offsetof(struct cgroup, procs_file), |
6612f05b TH |
4417 | .seq_start = cgroup_pidlist_start, |
4418 | .seq_next = cgroup_pidlist_next, | |
4419 | .seq_stop = cgroup_pidlist_stop, | |
4420 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 4421 | .private = CGROUP_FILE_PROCS, |
acbef755 | 4422 | .write = cgroup_procs_write, |
102a775e | 4423 | }, |
f8f22e53 TH |
4424 | { |
4425 | .name = "cgroup.controllers", | |
a14c6874 | 4426 | .flags = CFTYPE_ONLY_ON_ROOT, |
f8f22e53 TH |
4427 | .seq_show = cgroup_root_controllers_show, |
4428 | }, | |
4429 | { | |
4430 | .name = "cgroup.controllers", | |
a14c6874 | 4431 | .flags = CFTYPE_NOT_ON_ROOT, |
f8f22e53 TH |
4432 | .seq_show = cgroup_controllers_show, |
4433 | }, | |
4434 | { | |
4435 | .name = "cgroup.subtree_control", | |
f8f22e53 | 4436 | .seq_show = cgroup_subtree_control_show, |
451af504 | 4437 | .write = cgroup_subtree_control_write, |
f8f22e53 | 4438 | }, |
842b597e | 4439 | { |
4a07c222 | 4440 | .name = "cgroup.events", |
a14c6874 | 4441 | .flags = CFTYPE_NOT_ON_ROOT, |
6f60eade | 4442 | .file_offset = offsetof(struct cgroup, events_file), |
4a07c222 | 4443 | .seq_show = cgroup_events_show, |
842b597e | 4444 | }, |
a14c6874 TH |
4445 | { } /* terminate */ |
4446 | }; | |
d5c56ced | 4447 | |
a14c6874 TH |
4448 | /* cgroup core interface files for the legacy hierarchies */ |
4449 | static struct cftype cgroup_legacy_base_files[] = { | |
4450 | { | |
4451 | .name = "cgroup.procs", | |
4452 | .seq_start = cgroup_pidlist_start, | |
4453 | .seq_next = cgroup_pidlist_next, | |
4454 | .seq_stop = cgroup_pidlist_stop, | |
4455 | .seq_show = cgroup_pidlist_show, | |
4456 | .private = CGROUP_FILE_PROCS, | |
4457 | .write = cgroup_procs_write, | |
a14c6874 TH |
4458 | }, |
4459 | { | |
4460 | .name = "cgroup.clone_children", | |
4461 | .read_u64 = cgroup_clone_children_read, | |
4462 | .write_u64 = cgroup_clone_children_write, | |
4463 | }, | |
4464 | { | |
4465 | .name = "cgroup.sane_behavior", | |
4466 | .flags = CFTYPE_ONLY_ON_ROOT, | |
4467 | .seq_show = cgroup_sane_behavior_show, | |
4468 | }, | |
d5c56ced TH |
4469 | { |
4470 | .name = "tasks", | |
6612f05b TH |
4471 | .seq_start = cgroup_pidlist_start, |
4472 | .seq_next = cgroup_pidlist_next, | |
4473 | .seq_stop = cgroup_pidlist_stop, | |
4474 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 4475 | .private = CGROUP_FILE_TASKS, |
acbef755 | 4476 | .write = cgroup_tasks_write, |
d5c56ced TH |
4477 | }, |
4478 | { | |
4479 | .name = "notify_on_release", | |
d5c56ced TH |
4480 | .read_u64 = cgroup_read_notify_on_release, |
4481 | .write_u64 = cgroup_write_notify_on_release, | |
4482 | }, | |
6e6ff25b TH |
4483 | { |
4484 | .name = "release_agent", | |
a14c6874 | 4485 | .flags = CFTYPE_ONLY_ON_ROOT, |
2da8ca82 | 4486 | .seq_show = cgroup_release_agent_show, |
451af504 | 4487 | .write = cgroup_release_agent_write, |
5f469907 | 4488 | .max_write_len = PATH_MAX - 1, |
6e6ff25b | 4489 | }, |
db0416b6 | 4490 | { } /* terminate */ |
bbcb81d0 PM |
4491 | }; |
4492 | ||
0c21ead1 TH |
4493 | /* |
4494 | * css destruction is four-stage process. | |
4495 | * | |
4496 | * 1. Destruction starts. Killing of the percpu_ref is initiated. | |
4497 | * Implemented in kill_css(). | |
4498 | * | |
4499 | * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs | |
ec903c0c TH |
4500 | * and thus css_tryget_online() is guaranteed to fail, the css can be |
4501 | * offlined by invoking offline_css(). After offlining, the base ref is | |
4502 | * put. Implemented in css_killed_work_fn(). | |
0c21ead1 TH |
4503 | * |
4504 | * 3. When the percpu_ref reaches zero, the only possible remaining | |
4505 | * accessors are inside RCU read sections. css_release() schedules the | |
4506 | * RCU callback. | |
4507 | * | |
4508 | * 4. After the grace period, the css can be freed. Implemented in | |
4509 | * css_free_work_fn(). | |
4510 | * | |
4511 | * It is actually hairier because both step 2 and 4 require process context | |
4512 | * and thus involve punting to css->destroy_work adding two additional | |
4513 | * steps to the already complex sequence. | |
4514 | */ | |
35ef10da | 4515 | static void css_free_work_fn(struct work_struct *work) |
48ddbe19 TH |
4516 | { |
4517 | struct cgroup_subsys_state *css = | |
35ef10da | 4518 | container_of(work, struct cgroup_subsys_state, destroy_work); |
01e58659 | 4519 | struct cgroup_subsys *ss = css->ss; |
0c21ead1 | 4520 | struct cgroup *cgrp = css->cgroup; |
6f60eade | 4521 | struct cgroup_file *cfile; |
48ddbe19 | 4522 | |
9a1049da TH |
4523 | percpu_ref_exit(&css->refcnt); |
4524 | ||
6f60eade TH |
4525 | list_for_each_entry(cfile, &css->files, node) |
4526 | kernfs_put(cfile->kn); | |
4527 | ||
01e58659 | 4528 | if (ss) { |
9d755d33 | 4529 | /* css free path */ |
01e58659 VD |
4530 | int id = css->id; |
4531 | ||
9d755d33 TH |
4532 | if (css->parent) |
4533 | css_put(css->parent); | |
0ae78e0b | 4534 | |
01e58659 VD |
4535 | ss->css_free(css); |
4536 | cgroup_idr_remove(&ss->css_idr, id); | |
9d755d33 TH |
4537 | cgroup_put(cgrp); |
4538 | } else { | |
4539 | /* cgroup free path */ | |
4540 | atomic_dec(&cgrp->root->nr_cgrps); | |
4541 | cgroup_pidlist_destroy_all(cgrp); | |
971ff493 | 4542 | cancel_work_sync(&cgrp->release_agent_work); |
9d755d33 | 4543 | |
d51f39b0 | 4544 | if (cgroup_parent(cgrp)) { |
9d755d33 TH |
4545 | /* |
4546 | * We get a ref to the parent, and put the ref when | |
4547 | * this cgroup is being freed, so it's guaranteed | |
4548 | * that the parent won't be destroyed before its | |
4549 | * children. | |
4550 | */ | |
d51f39b0 | 4551 | cgroup_put(cgroup_parent(cgrp)); |
9d755d33 TH |
4552 | kernfs_put(cgrp->kn); |
4553 | kfree(cgrp); | |
4554 | } else { | |
4555 | /* | |
4556 | * This is root cgroup's refcnt reaching zero, | |
4557 | * which indicates that the root should be | |
4558 | * released. | |
4559 | */ | |
4560 | cgroup_destroy_root(cgrp->root); | |
4561 | } | |
4562 | } | |
48ddbe19 TH |
4563 | } |
4564 | ||
0c21ead1 | 4565 | static void css_free_rcu_fn(struct rcu_head *rcu_head) |
d3daf28d TH |
4566 | { |
4567 | struct cgroup_subsys_state *css = | |
0c21ead1 | 4568 | container_of(rcu_head, struct cgroup_subsys_state, rcu_head); |
d3daf28d | 4569 | |
35ef10da | 4570 | INIT_WORK(&css->destroy_work, css_free_work_fn); |
e5fca243 | 4571 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
48ddbe19 TH |
4572 | } |
4573 | ||
25e15d83 | 4574 | static void css_release_work_fn(struct work_struct *work) |
d3daf28d TH |
4575 | { |
4576 | struct cgroup_subsys_state *css = | |
25e15d83 | 4577 | container_of(work, struct cgroup_subsys_state, destroy_work); |
15a4c835 | 4578 | struct cgroup_subsys *ss = css->ss; |
9d755d33 | 4579 | struct cgroup *cgrp = css->cgroup; |
15a4c835 | 4580 | |
1fed1b2e TH |
4581 | mutex_lock(&cgroup_mutex); |
4582 | ||
de3f0341 | 4583 | css->flags |= CSS_RELEASED; |
1fed1b2e TH |
4584 | list_del_rcu(&css->sibling); |
4585 | ||
9d755d33 TH |
4586 | if (ss) { |
4587 | /* css release path */ | |
01e58659 | 4588 | cgroup_idr_replace(&ss->css_idr, NULL, css->id); |
7d172cc8 TH |
4589 | if (ss->css_released) |
4590 | ss->css_released(css); | |
9d755d33 TH |
4591 | } else { |
4592 | /* cgroup release path */ | |
9d755d33 TH |
4593 | cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id); |
4594 | cgrp->id = -1; | |
a4189487 LZ |
4595 | |
4596 | /* | |
4597 | * There are two control paths which try to determine | |
4598 | * cgroup from dentry without going through kernfs - | |
4599 | * cgroupstats_build() and css_tryget_online_from_dir(). | |
4600 | * Those are supported by RCU protecting clearing of | |
4601 | * cgrp->kn->priv backpointer. | |
4602 | */ | |
4603 | RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL); | |
9d755d33 | 4604 | } |
d3daf28d | 4605 | |
1fed1b2e TH |
4606 | mutex_unlock(&cgroup_mutex); |
4607 | ||
0c21ead1 | 4608 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
d3daf28d TH |
4609 | } |
4610 | ||
d3daf28d TH |
4611 | static void css_release(struct percpu_ref *ref) |
4612 | { | |
4613 | struct cgroup_subsys_state *css = | |
4614 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4615 | ||
25e15d83 TH |
4616 | INIT_WORK(&css->destroy_work, css_release_work_fn); |
4617 | queue_work(cgroup_destroy_wq, &css->destroy_work); | |
d3daf28d TH |
4618 | } |
4619 | ||
ddfcadab TH |
4620 | static void init_and_link_css(struct cgroup_subsys_state *css, |
4621 | struct cgroup_subsys *ss, struct cgroup *cgrp) | |
ddbcc7e8 | 4622 | { |
0cb51d71 TH |
4623 | lockdep_assert_held(&cgroup_mutex); |
4624 | ||
ddfcadab TH |
4625 | cgroup_get(cgrp); |
4626 | ||
d5c419b6 | 4627 | memset(css, 0, sizeof(*css)); |
bd89aabc | 4628 | css->cgroup = cgrp; |
72c97e54 | 4629 | css->ss = ss; |
d5c419b6 TH |
4630 | INIT_LIST_HEAD(&css->sibling); |
4631 | INIT_LIST_HEAD(&css->children); | |
6f60eade | 4632 | INIT_LIST_HEAD(&css->files); |
0cb51d71 | 4633 | css->serial_nr = css_serial_nr_next++; |
0ae78e0b | 4634 | |
d51f39b0 TH |
4635 | if (cgroup_parent(cgrp)) { |
4636 | css->parent = cgroup_css(cgroup_parent(cgrp), ss); | |
ddfcadab | 4637 | css_get(css->parent); |
ddfcadab | 4638 | } |
48ddbe19 | 4639 | |
ca8bdcaf | 4640 | BUG_ON(cgroup_css(cgrp, ss)); |
ddbcc7e8 PM |
4641 | } |
4642 | ||
2a4ac633 | 4643 | /* invoke ->css_online() on a new CSS and mark it online if successful */ |
623f926b | 4644 | static int online_css(struct cgroup_subsys_state *css) |
a31f2d3f | 4645 | { |
623f926b | 4646 | struct cgroup_subsys *ss = css->ss; |
b1929db4 TH |
4647 | int ret = 0; |
4648 | ||
a31f2d3f TH |
4649 | lockdep_assert_held(&cgroup_mutex); |
4650 | ||
92fb9748 | 4651 | if (ss->css_online) |
eb95419b | 4652 | ret = ss->css_online(css); |
ae7f164a | 4653 | if (!ret) { |
eb95419b | 4654 | css->flags |= CSS_ONLINE; |
aec25020 | 4655 | rcu_assign_pointer(css->cgroup->subsys[ss->id], css); |
ae7f164a | 4656 | } |
b1929db4 | 4657 | return ret; |
a31f2d3f TH |
4658 | } |
4659 | ||
2a4ac633 | 4660 | /* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
623f926b | 4661 | static void offline_css(struct cgroup_subsys_state *css) |
a31f2d3f | 4662 | { |
623f926b | 4663 | struct cgroup_subsys *ss = css->ss; |
a31f2d3f TH |
4664 | |
4665 | lockdep_assert_held(&cgroup_mutex); | |
4666 | ||
4667 | if (!(css->flags & CSS_ONLINE)) | |
4668 | return; | |
4669 | ||
d7eeac19 | 4670 | if (ss->css_offline) |
eb95419b | 4671 | ss->css_offline(css); |
a31f2d3f | 4672 | |
eb95419b | 4673 | css->flags &= ~CSS_ONLINE; |
e3297803 | 4674 | RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL); |
f8f22e53 TH |
4675 | |
4676 | wake_up_all(&css->cgroup->offline_waitq); | |
a31f2d3f TH |
4677 | } |
4678 | ||
c81c925a TH |
4679 | /** |
4680 | * create_css - create a cgroup_subsys_state | |
4681 | * @cgrp: the cgroup new css will be associated with | |
4682 | * @ss: the subsys of new css | |
f63070d3 | 4683 | * @visible: whether to create control knobs for the new css or not |
c81c925a TH |
4684 | * |
4685 | * Create a new css associated with @cgrp - @ss pair. On success, the new | |
f63070d3 TH |
4686 | * css is online and installed in @cgrp with all interface files created if |
4687 | * @visible. Returns 0 on success, -errno on failure. | |
c81c925a | 4688 | */ |
f63070d3 TH |
4689 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, |
4690 | bool visible) | |
c81c925a | 4691 | { |
d51f39b0 | 4692 | struct cgroup *parent = cgroup_parent(cgrp); |
1fed1b2e | 4693 | struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss); |
c81c925a TH |
4694 | struct cgroup_subsys_state *css; |
4695 | int err; | |
4696 | ||
c81c925a TH |
4697 | lockdep_assert_held(&cgroup_mutex); |
4698 | ||
1fed1b2e | 4699 | css = ss->css_alloc(parent_css); |
c81c925a TH |
4700 | if (IS_ERR(css)) |
4701 | return PTR_ERR(css); | |
4702 | ||
ddfcadab | 4703 | init_and_link_css(css, ss, cgrp); |
a2bed820 | 4704 | |
2aad2a86 | 4705 | err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL); |
c81c925a | 4706 | if (err) |
3eb59ec6 | 4707 | goto err_free_css; |
c81c925a | 4708 | |
cf780b7d | 4709 | err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL); |
15a4c835 TH |
4710 | if (err < 0) |
4711 | goto err_free_percpu_ref; | |
4712 | css->id = err; | |
c81c925a | 4713 | |
f63070d3 | 4714 | if (visible) { |
4df8dc90 | 4715 | err = css_populate_dir(css, NULL); |
f63070d3 TH |
4716 | if (err) |
4717 | goto err_free_id; | |
4718 | } | |
15a4c835 TH |
4719 | |
4720 | /* @css is ready to be brought online now, make it visible */ | |
1fed1b2e | 4721 | list_add_tail_rcu(&css->sibling, &parent_css->children); |
15a4c835 | 4722 | cgroup_idr_replace(&ss->css_idr, css, css->id); |
c81c925a TH |
4723 | |
4724 | err = online_css(css); | |
4725 | if (err) | |
1fed1b2e | 4726 | goto err_list_del; |
94419627 | 4727 | |
c81c925a | 4728 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && |
d51f39b0 | 4729 | cgroup_parent(parent)) { |
ed3d261b | 4730 | pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", |
a2a1f9ea | 4731 | current->comm, current->pid, ss->name); |
c81c925a | 4732 | if (!strcmp(ss->name, "memory")) |
ed3d261b | 4733 | pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n"); |
c81c925a TH |
4734 | ss->warned_broken_hierarchy = true; |
4735 | } | |
4736 | ||
4737 | return 0; | |
4738 | ||
1fed1b2e TH |
4739 | err_list_del: |
4740 | list_del_rcu(&css->sibling); | |
4df8dc90 | 4741 | css_clear_dir(css, NULL); |
15a4c835 TH |
4742 | err_free_id: |
4743 | cgroup_idr_remove(&ss->css_idr, css->id); | |
3eb59ec6 | 4744 | err_free_percpu_ref: |
9a1049da | 4745 | percpu_ref_exit(&css->refcnt); |
3eb59ec6 | 4746 | err_free_css: |
a2bed820 | 4747 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
c81c925a TH |
4748 | return err; |
4749 | } | |
4750 | ||
b3bfd983 TH |
4751 | static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, |
4752 | umode_t mode) | |
ddbcc7e8 | 4753 | { |
a9746d8d TH |
4754 | struct cgroup *parent, *cgrp; |
4755 | struct cgroup_root *root; | |
ddbcc7e8 | 4756 | struct cgroup_subsys *ss; |
2bd59d48 | 4757 | struct kernfs_node *kn; |
b3bfd983 | 4758 | int ssid, ret; |
ddbcc7e8 | 4759 | |
71b1fb5c AC |
4760 | /* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable. |
4761 | */ | |
4762 | if (strchr(name, '\n')) | |
4763 | return -EINVAL; | |
4764 | ||
a9746d8d TH |
4765 | parent = cgroup_kn_lock_live(parent_kn); |
4766 | if (!parent) | |
4767 | return -ENODEV; | |
4768 | root = parent->root; | |
ddbcc7e8 | 4769 | |
0a950f65 | 4770 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
bd89aabc | 4771 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
ba0f4d76 TH |
4772 | if (!cgrp) { |
4773 | ret = -ENOMEM; | |
4774 | goto out_unlock; | |
0ab02ca8 LZ |
4775 | } |
4776 | ||
2aad2a86 | 4777 | ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL); |
9d755d33 TH |
4778 | if (ret) |
4779 | goto out_free_cgrp; | |
4780 | ||
0ab02ca8 LZ |
4781 | /* |
4782 | * Temporarily set the pointer to NULL, so idr_find() won't return | |
4783 | * a half-baked cgroup. | |
4784 | */ | |
cf780b7d | 4785 | cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL); |
0ab02ca8 | 4786 | if (cgrp->id < 0) { |
ba0f4d76 | 4787 | ret = -ENOMEM; |
9d755d33 | 4788 | goto out_cancel_ref; |
976c06bc TH |
4789 | } |
4790 | ||
cc31edce | 4791 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 4792 | |
9d800df1 | 4793 | cgrp->self.parent = &parent->self; |
ba0f4d76 | 4794 | cgrp->root = root; |
ddbcc7e8 | 4795 | |
b6abdb0e LZ |
4796 | if (notify_on_release(parent)) |
4797 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
4798 | ||
2260e7fc TH |
4799 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
4800 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 4801 | |
2bd59d48 | 4802 | /* create the directory */ |
e61734c5 | 4803 | kn = kernfs_create_dir(parent->kn, name, mode, cgrp); |
2bd59d48 | 4804 | if (IS_ERR(kn)) { |
ba0f4d76 TH |
4805 | ret = PTR_ERR(kn); |
4806 | goto out_free_id; | |
2bd59d48 TH |
4807 | } |
4808 | cgrp->kn = kn; | |
ddbcc7e8 | 4809 | |
4e139afc | 4810 | /* |
6f30558f TH |
4811 | * This extra ref will be put in cgroup_free_fn() and guarantees |
4812 | * that @cgrp->kn is always accessible. | |
4e139afc | 4813 | */ |
6f30558f | 4814 | kernfs_get(kn); |
ddbcc7e8 | 4815 | |
0cb51d71 | 4816 | cgrp->self.serial_nr = css_serial_nr_next++; |
53fa5261 | 4817 | |
4e139afc | 4818 | /* allocation complete, commit to creation */ |
d5c419b6 | 4819 | list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children); |
3c9c825b | 4820 | atomic_inc(&root->nr_cgrps); |
59f5296b | 4821 | cgroup_get(parent); |
415cf07a | 4822 | |
0d80255e TH |
4823 | /* |
4824 | * @cgrp is now fully operational. If something fails after this | |
4825 | * point, it'll be released via the normal destruction path. | |
4826 | */ | |
6fa4918d | 4827 | cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
4e96ee8e | 4828 | |
ba0f4d76 TH |
4829 | ret = cgroup_kn_set_ugid(kn); |
4830 | if (ret) | |
4831 | goto out_destroy; | |
49957f8e | 4832 | |
4df8dc90 | 4833 | ret = css_populate_dir(&cgrp->self, NULL); |
ba0f4d76 TH |
4834 | if (ret) |
4835 | goto out_destroy; | |
628f7cd4 | 4836 | |
9d403e99 | 4837 | /* let's create and online css's */ |
b85d2040 | 4838 | for_each_subsys(ss, ssid) { |
f392e51c | 4839 | if (parent->child_subsys_mask & (1 << ssid)) { |
f63070d3 TH |
4840 | ret = create_css(cgrp, ss, |
4841 | parent->subtree_control & (1 << ssid)); | |
ba0f4d76 TH |
4842 | if (ret) |
4843 | goto out_destroy; | |
b85d2040 | 4844 | } |
a8638030 | 4845 | } |
ddbcc7e8 | 4846 | |
bd53d617 TH |
4847 | /* |
4848 | * On the default hierarchy, a child doesn't automatically inherit | |
667c2491 | 4849 | * subtree_control from the parent. Each is configured manually. |
bd53d617 | 4850 | */ |
667c2491 TH |
4851 | if (!cgroup_on_dfl(cgrp)) { |
4852 | cgrp->subtree_control = parent->subtree_control; | |
4853 | cgroup_refresh_child_subsys_mask(cgrp); | |
4854 | } | |
2bd59d48 | 4855 | |
2bd59d48 | 4856 | kernfs_activate(kn); |
ddbcc7e8 | 4857 | |
ba0f4d76 TH |
4858 | ret = 0; |
4859 | goto out_unlock; | |
ddbcc7e8 | 4860 | |
ba0f4d76 | 4861 | out_free_id: |
6fa4918d | 4862 | cgroup_idr_remove(&root->cgroup_idr, cgrp->id); |
9d755d33 | 4863 | out_cancel_ref: |
9a1049da | 4864 | percpu_ref_exit(&cgrp->self.refcnt); |
ba0f4d76 | 4865 | out_free_cgrp: |
bd89aabc | 4866 | kfree(cgrp); |
ba0f4d76 | 4867 | out_unlock: |
a9746d8d | 4868 | cgroup_kn_unlock(parent_kn); |
ba0f4d76 | 4869 | return ret; |
4b8b47eb | 4870 | |
ba0f4d76 | 4871 | out_destroy: |
4b8b47eb | 4872 | cgroup_destroy_locked(cgrp); |
ba0f4d76 | 4873 | goto out_unlock; |
ddbcc7e8 PM |
4874 | } |
4875 | ||
223dbc38 TH |
4876 | /* |
4877 | * This is called when the refcnt of a css is confirmed to be killed. | |
249f3468 TH |
4878 | * css_tryget_online() is now guaranteed to fail. Tell the subsystem to |
4879 | * initate destruction and put the css ref from kill_css(). | |
223dbc38 TH |
4880 | */ |
4881 | static void css_killed_work_fn(struct work_struct *work) | |
d3daf28d | 4882 | { |
223dbc38 TH |
4883 | struct cgroup_subsys_state *css = |
4884 | container_of(work, struct cgroup_subsys_state, destroy_work); | |
d3daf28d | 4885 | |
f20104de | 4886 | mutex_lock(&cgroup_mutex); |
09a503ea | 4887 | offline_css(css); |
f20104de | 4888 | mutex_unlock(&cgroup_mutex); |
09a503ea | 4889 | |
09a503ea | 4890 | css_put(css); |
d3daf28d TH |
4891 | } |
4892 | ||
223dbc38 TH |
4893 | /* css kill confirmation processing requires process context, bounce */ |
4894 | static void css_killed_ref_fn(struct percpu_ref *ref) | |
d3daf28d TH |
4895 | { |
4896 | struct cgroup_subsys_state *css = | |
4897 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4898 | ||
223dbc38 | 4899 | INIT_WORK(&css->destroy_work, css_killed_work_fn); |
e5fca243 | 4900 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
d3daf28d TH |
4901 | } |
4902 | ||
f392e51c TH |
4903 | /** |
4904 | * kill_css - destroy a css | |
4905 | * @css: css to destroy | |
4906 | * | |
4907 | * This function initiates destruction of @css by removing cgroup interface | |
4908 | * files and putting its base reference. ->css_offline() will be invoked | |
ec903c0c TH |
4909 | * asynchronously once css_tryget_online() is guaranteed to fail and when |
4910 | * the reference count reaches zero, @css will be released. | |
f392e51c TH |
4911 | */ |
4912 | static void kill_css(struct cgroup_subsys_state *css) | |
edae0c33 | 4913 | { |
01f6474c | 4914 | lockdep_assert_held(&cgroup_mutex); |
94419627 | 4915 | |
2bd59d48 TH |
4916 | /* |
4917 | * This must happen before css is disassociated with its cgroup. | |
4918 | * See seq_css() for details. | |
4919 | */ | |
4df8dc90 | 4920 | css_clear_dir(css, NULL); |
3c14f8b4 | 4921 | |
edae0c33 TH |
4922 | /* |
4923 | * Killing would put the base ref, but we need to keep it alive | |
4924 | * until after ->css_offline(). | |
4925 | */ | |
4926 | css_get(css); | |
4927 | ||
4928 | /* | |
4929 | * cgroup core guarantees that, by the time ->css_offline() is | |
4930 | * invoked, no new css reference will be given out via | |
ec903c0c | 4931 | * css_tryget_online(). We can't simply call percpu_ref_kill() and |
edae0c33 TH |
4932 | * proceed to offlining css's because percpu_ref_kill() doesn't |
4933 | * guarantee that the ref is seen as killed on all CPUs on return. | |
4934 | * | |
4935 | * Use percpu_ref_kill_and_confirm() to get notifications as each | |
4936 | * css is confirmed to be seen as killed on all CPUs. | |
4937 | */ | |
4938 | percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn); | |
d3daf28d TH |
4939 | } |
4940 | ||
4941 | /** | |
4942 | * cgroup_destroy_locked - the first stage of cgroup destruction | |
4943 | * @cgrp: cgroup to be destroyed | |
4944 | * | |
4945 | * css's make use of percpu refcnts whose killing latency shouldn't be | |
4946 | * exposed to userland and are RCU protected. Also, cgroup core needs to | |
ec903c0c TH |
4947 | * guarantee that css_tryget_online() won't succeed by the time |
4948 | * ->css_offline() is invoked. To satisfy all the requirements, | |
4949 | * destruction is implemented in the following two steps. | |
d3daf28d TH |
4950 | * |
4951 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all | |
4952 | * userland visible parts and start killing the percpu refcnts of | |
4953 | * css's. Set up so that the next stage will be kicked off once all | |
4954 | * the percpu refcnts are confirmed to be killed. | |
4955 | * | |
4956 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the | |
4957 | * rest of destruction. Once all cgroup references are gone, the | |
4958 | * cgroup is RCU-freed. | |
4959 | * | |
4960 | * This function implements s1. After this step, @cgrp is gone as far as | |
4961 | * the userland is concerned and a new cgroup with the same name may be | |
4962 | * created. As cgroup doesn't care about the names internally, this | |
4963 | * doesn't cause any problem. | |
4964 | */ | |
42809dd4 TH |
4965 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
4966 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 4967 | { |
2bd59d48 | 4968 | struct cgroup_subsys_state *css; |
ddd69148 | 4969 | bool empty; |
1c6727af | 4970 | int ssid; |
ddbcc7e8 | 4971 | |
42809dd4 TH |
4972 | lockdep_assert_held(&cgroup_mutex); |
4973 | ||
ddd69148 | 4974 | /* |
96d365e0 | 4975 | * css_set_rwsem synchronizes access to ->cset_links and prevents |
89c5509b | 4976 | * @cgrp from being removed while put_css_set() is in progress. |
ddd69148 | 4977 | */ |
96d365e0 | 4978 | down_read(&css_set_rwsem); |
bb78a92f | 4979 | empty = list_empty(&cgrp->cset_links); |
96d365e0 | 4980 | up_read(&css_set_rwsem); |
ddd69148 | 4981 | if (!empty) |
ddbcc7e8 | 4982 | return -EBUSY; |
a043e3b2 | 4983 | |
bb78a92f | 4984 | /* |
d5c419b6 TH |
4985 | * Make sure there's no live children. We can't test emptiness of |
4986 | * ->self.children as dead children linger on it while being | |
4987 | * drained; otherwise, "rmdir parent/child parent" may fail. | |
bb78a92f | 4988 | */ |
f3d46500 | 4989 | if (css_has_online_children(&cgrp->self)) |
bb78a92f HD |
4990 | return -EBUSY; |
4991 | ||
455050d2 TH |
4992 | /* |
4993 | * Mark @cgrp dead. This prevents further task migration and child | |
de3f0341 | 4994 | * creation by disabling cgroup_lock_live_group(). |
455050d2 | 4995 | */ |
184faf32 | 4996 | cgrp->self.flags &= ~CSS_ONLINE; |
ddbcc7e8 | 4997 | |
249f3468 | 4998 | /* initiate massacre of all css's */ |
1c6727af TH |
4999 | for_each_css(css, ssid, cgrp) |
5000 | kill_css(css); | |
455050d2 | 5001 | |
455050d2 | 5002 | /* |
01f6474c TH |
5003 | * Remove @cgrp directory along with the base files. @cgrp has an |
5004 | * extra ref on its kn. | |
f20104de | 5005 | */ |
01f6474c | 5006 | kernfs_remove(cgrp->kn); |
f20104de | 5007 | |
d51f39b0 | 5008 | check_for_release(cgroup_parent(cgrp)); |
2bd59d48 | 5009 | |
249f3468 | 5010 | /* put the base reference */ |
9d755d33 | 5011 | percpu_ref_kill(&cgrp->self.refcnt); |
455050d2 | 5012 | |
ea15f8cc TH |
5013 | return 0; |
5014 | }; | |
5015 | ||
2bd59d48 | 5016 | static int cgroup_rmdir(struct kernfs_node *kn) |
42809dd4 | 5017 | { |
a9746d8d | 5018 | struct cgroup *cgrp; |
2bd59d48 | 5019 | int ret = 0; |
42809dd4 | 5020 | |
a9746d8d TH |
5021 | cgrp = cgroup_kn_lock_live(kn); |
5022 | if (!cgrp) | |
5023 | return 0; | |
42809dd4 | 5024 | |
a9746d8d | 5025 | ret = cgroup_destroy_locked(cgrp); |
2bb566cb | 5026 | |
a9746d8d | 5027 | cgroup_kn_unlock(kn); |
42809dd4 | 5028 | return ret; |
8e3f6541 TH |
5029 | } |
5030 | ||
2bd59d48 TH |
5031 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
5032 | .remount_fs = cgroup_remount, | |
5033 | .show_options = cgroup_show_options, | |
5034 | .mkdir = cgroup_mkdir, | |
5035 | .rmdir = cgroup_rmdir, | |
5036 | .rename = cgroup_rename, | |
5037 | }; | |
5038 | ||
15a4c835 | 5039 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early) |
ddbcc7e8 | 5040 | { |
ddbcc7e8 | 5041 | struct cgroup_subsys_state *css; |
cfe36bde DC |
5042 | |
5043 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 5044 | |
648bb56d TH |
5045 | mutex_lock(&cgroup_mutex); |
5046 | ||
15a4c835 | 5047 | idr_init(&ss->css_idr); |
0adb0704 | 5048 | INIT_LIST_HEAD(&ss->cfts); |
8e3f6541 | 5049 | |
3dd06ffa TH |
5050 | /* Create the root cgroup state for this subsystem */ |
5051 | ss->root = &cgrp_dfl_root; | |
5052 | css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss)); | |
ddbcc7e8 PM |
5053 | /* We don't handle early failures gracefully */ |
5054 | BUG_ON(IS_ERR(css)); | |
ddfcadab | 5055 | init_and_link_css(css, ss, &cgrp_dfl_root.cgrp); |
3b514d24 TH |
5056 | |
5057 | /* | |
5058 | * Root csses are never destroyed and we can't initialize | |
5059 | * percpu_ref during early init. Disable refcnting. | |
5060 | */ | |
5061 | css->flags |= CSS_NO_REF; | |
5062 | ||
15a4c835 | 5063 | if (early) { |
9395a450 | 5064 | /* allocation can't be done safely during early init */ |
15a4c835 TH |
5065 | css->id = 1; |
5066 | } else { | |
5067 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL); | |
5068 | BUG_ON(css->id < 0); | |
5069 | } | |
ddbcc7e8 | 5070 | |
e8d55fde | 5071 | /* Update the init_css_set to contain a subsys |
817929ec | 5072 | * pointer to this state - since the subsystem is |
e8d55fde | 5073 | * newly registered, all tasks and hence the |
3dd06ffa | 5074 | * init_css_set is in the subsystem's root cgroup. */ |
aec25020 | 5075 | init_css_set.subsys[ss->id] = css; |
ddbcc7e8 | 5076 | |
cb4a3167 AS |
5077 | have_fork_callback |= (bool)ss->fork << ss->id; |
5078 | have_exit_callback |= (bool)ss->exit << ss->id; | |
7e47682e | 5079 | have_canfork_callback |= (bool)ss->can_fork << ss->id; |
ddbcc7e8 | 5080 | |
e8d55fde LZ |
5081 | /* At system boot, before all subsystems have been |
5082 | * registered, no tasks have been forked, so we don't | |
5083 | * need to invoke fork callbacks here. */ | |
5084 | BUG_ON(!list_empty(&init_task.tasks)); | |
5085 | ||
ae7f164a | 5086 | BUG_ON(online_css(css)); |
a8638030 | 5087 | |
cf5d5941 BB |
5088 | mutex_unlock(&cgroup_mutex); |
5089 | } | |
cf5d5941 | 5090 | |
ddbcc7e8 | 5091 | /** |
a043e3b2 LZ |
5092 | * cgroup_init_early - cgroup initialization at system boot |
5093 | * | |
5094 | * Initialize cgroups at system boot, and initialize any | |
5095 | * subsystems that request early init. | |
ddbcc7e8 PM |
5096 | */ |
5097 | int __init cgroup_init_early(void) | |
5098 | { | |
7b9a6ba5 | 5099 | static struct cgroup_sb_opts __initdata opts; |
30159ec7 | 5100 | struct cgroup_subsys *ss; |
ddbcc7e8 | 5101 | int i; |
30159ec7 | 5102 | |
3dd06ffa | 5103 | init_cgroup_root(&cgrp_dfl_root, &opts); |
3b514d24 TH |
5104 | cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF; |
5105 | ||
a4ea1cc9 | 5106 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
817929ec | 5107 | |
3ed80a62 | 5108 | for_each_subsys(ss, i) { |
aec25020 | 5109 | WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id, |
073219e9 TH |
5110 | "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n", |
5111 | i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free, | |
aec25020 | 5112 | ss->id, ss->name); |
073219e9 TH |
5113 | WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN, |
5114 | "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]); | |
5115 | ||
aec25020 | 5116 | ss->id = i; |
073219e9 | 5117 | ss->name = cgroup_subsys_name[i]; |
3e1d2eed TH |
5118 | if (!ss->legacy_name) |
5119 | ss->legacy_name = cgroup_subsys_name[i]; | |
ddbcc7e8 PM |
5120 | |
5121 | if (ss->early_init) | |
15a4c835 | 5122 | cgroup_init_subsys(ss, true); |
ddbcc7e8 PM |
5123 | } |
5124 | return 0; | |
5125 | } | |
5126 | ||
5127 | /** | |
a043e3b2 LZ |
5128 | * cgroup_init - cgroup initialization |
5129 | * | |
5130 | * Register cgroup filesystem and /proc file, and initialize | |
5131 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
5132 | */ |
5133 | int __init cgroup_init(void) | |
5134 | { | |
30159ec7 | 5135 | struct cgroup_subsys *ss; |
0ac801fe | 5136 | unsigned long key; |
172a2c06 | 5137 | int ssid, err; |
ddbcc7e8 | 5138 | |
1ed13287 | 5139 | BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem)); |
a14c6874 TH |
5140 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files)); |
5141 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files)); | |
ddbcc7e8 | 5142 | |
54e7b4eb | 5143 | mutex_lock(&cgroup_mutex); |
54e7b4eb | 5144 | |
82fe9b0d TH |
5145 | /* Add init_css_set to the hash table */ |
5146 | key = css_set_hash(init_css_set.subsys); | |
5147 | hash_add(css_set_table, &init_css_set.hlist, key); | |
5148 | ||
3dd06ffa | 5149 | BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0)); |
4e96ee8e | 5150 | |
54e7b4eb TH |
5151 | mutex_unlock(&cgroup_mutex); |
5152 | ||
172a2c06 | 5153 | for_each_subsys(ss, ssid) { |
15a4c835 TH |
5154 | if (ss->early_init) { |
5155 | struct cgroup_subsys_state *css = | |
5156 | init_css_set.subsys[ss->id]; | |
5157 | ||
5158 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, | |
5159 | GFP_KERNEL); | |
5160 | BUG_ON(css->id < 0); | |
5161 | } else { | |
5162 | cgroup_init_subsys(ss, false); | |
5163 | } | |
172a2c06 | 5164 | |
2d8f243a TH |
5165 | list_add_tail(&init_css_set.e_cset_node[ssid], |
5166 | &cgrp_dfl_root.cgrp.e_csets[ssid]); | |
172a2c06 TH |
5167 | |
5168 | /* | |
c731ae1d LZ |
5169 | * Setting dfl_root subsys_mask needs to consider the |
5170 | * disabled flag and cftype registration needs kmalloc, | |
5171 | * both of which aren't available during early_init. | |
172a2c06 | 5172 | */ |
fc5ed1e9 | 5173 | if (!cgroup_ssid_enabled(ssid)) |
a8ddc821 TH |
5174 | continue; |
5175 | ||
5176 | cgrp_dfl_root.subsys_mask |= 1 << ss->id; | |
5177 | ||
5178 | if (cgroup_legacy_files_on_dfl && !ss->dfl_cftypes) | |
5179 | ss->dfl_cftypes = ss->legacy_cftypes; | |
5180 | ||
5de4fa13 TH |
5181 | if (!ss->dfl_cftypes) |
5182 | cgrp_dfl_root_inhibit_ss_mask |= 1 << ss->id; | |
5183 | ||
a8ddc821 TH |
5184 | if (ss->dfl_cftypes == ss->legacy_cftypes) { |
5185 | WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes)); | |
5186 | } else { | |
5187 | WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes)); | |
5188 | WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes)); | |
c731ae1d | 5189 | } |
295458e6 VD |
5190 | |
5191 | if (ss->bind) | |
5192 | ss->bind(init_css_set.subsys[ssid]); | |
676db4af GK |
5193 | } |
5194 | ||
f9bb4882 EB |
5195 | err = sysfs_create_mount_point(fs_kobj, "cgroup"); |
5196 | if (err) | |
5197 | return err; | |
676db4af | 5198 | |
ddbcc7e8 | 5199 | err = register_filesystem(&cgroup_fs_type); |
676db4af | 5200 | if (err < 0) { |
f9bb4882 | 5201 | sysfs_remove_mount_point(fs_kobj, "cgroup"); |
2bd59d48 | 5202 | return err; |
676db4af | 5203 | } |
ddbcc7e8 | 5204 | |
46ae220b | 5205 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
2bd59d48 | 5206 | return 0; |
ddbcc7e8 | 5207 | } |
b4f48b63 | 5208 | |
e5fca243 TH |
5209 | static int __init cgroup_wq_init(void) |
5210 | { | |
5211 | /* | |
5212 | * There isn't much point in executing destruction path in | |
5213 | * parallel. Good chunk is serialized with cgroup_mutex anyway. | |
1a11533f | 5214 | * Use 1 for @max_active. |
e5fca243 TH |
5215 | * |
5216 | * We would prefer to do this in cgroup_init() above, but that | |
5217 | * is called before init_workqueues(): so leave this until after. | |
5218 | */ | |
1a11533f | 5219 | cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); |
e5fca243 | 5220 | BUG_ON(!cgroup_destroy_wq); |
b1a21367 TH |
5221 | |
5222 | /* | |
5223 | * Used to destroy pidlists and separate to serve as flush domain. | |
5224 | * Cap @max_active to 1 too. | |
5225 | */ | |
5226 | cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", | |
5227 | 0, 1); | |
5228 | BUG_ON(!cgroup_pidlist_destroy_wq); | |
5229 | ||
e5fca243 TH |
5230 | return 0; |
5231 | } | |
5232 | core_initcall(cgroup_wq_init); | |
5233 | ||
a424316c PM |
5234 | /* |
5235 | * proc_cgroup_show() | |
5236 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
5237 | * - Used for /proc/<pid>/cgroup. | |
a424316c | 5238 | */ |
006f4ac4 ZL |
5239 | int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, |
5240 | struct pid *pid, struct task_struct *tsk) | |
a424316c | 5241 | { |
e61734c5 | 5242 | char *buf, *path; |
a424316c | 5243 | int retval; |
3dd06ffa | 5244 | struct cgroup_root *root; |
a424316c PM |
5245 | |
5246 | retval = -ENOMEM; | |
e61734c5 | 5247 | buf = kmalloc(PATH_MAX, GFP_KERNEL); |
a424316c PM |
5248 | if (!buf) |
5249 | goto out; | |
5250 | ||
a424316c | 5251 | mutex_lock(&cgroup_mutex); |
96d365e0 | 5252 | down_read(&css_set_rwsem); |
a424316c | 5253 | |
985ed670 | 5254 | for_each_root(root) { |
a424316c | 5255 | struct cgroup_subsys *ss; |
bd89aabc | 5256 | struct cgroup *cgrp; |
b85d2040 | 5257 | int ssid, count = 0; |
a424316c | 5258 | |
a2dd4247 | 5259 | if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible) |
985ed670 TH |
5260 | continue; |
5261 | ||
2c6ab6d2 | 5262 | seq_printf(m, "%d:", root->hierarchy_id); |
d98817d4 TH |
5263 | if (root != &cgrp_dfl_root) |
5264 | for_each_subsys(ss, ssid) | |
5265 | if (root->subsys_mask & (1 << ssid)) | |
5266 | seq_printf(m, "%s%s", count++ ? "," : "", | |
3e1d2eed | 5267 | ss->legacy_name); |
c6d57f33 PM |
5268 | if (strlen(root->name)) |
5269 | seq_printf(m, "%sname=%s", count ? "," : "", | |
5270 | root->name); | |
a424316c | 5271 | seq_putc(m, ':'); |
7717f7ba | 5272 | cgrp = task_cgroup_from_root(tsk, root); |
e61734c5 TH |
5273 | path = cgroup_path(cgrp, buf, PATH_MAX); |
5274 | if (!path) { | |
5275 | retval = -ENAMETOOLONG; | |
a424316c | 5276 | goto out_unlock; |
e61734c5 TH |
5277 | } |
5278 | seq_puts(m, path); | |
a424316c PM |
5279 | seq_putc(m, '\n'); |
5280 | } | |
5281 | ||
006f4ac4 | 5282 | retval = 0; |
a424316c | 5283 | out_unlock: |
96d365e0 | 5284 | up_read(&css_set_rwsem); |
a424316c | 5285 | mutex_unlock(&cgroup_mutex); |
a424316c PM |
5286 | kfree(buf); |
5287 | out: | |
5288 | return retval; | |
5289 | } | |
5290 | ||
a424316c PM |
5291 | /* Display information about each subsystem and each hierarchy */ |
5292 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
5293 | { | |
30159ec7 | 5294 | struct cgroup_subsys *ss; |
a424316c | 5295 | int i; |
a424316c | 5296 | |
8bab8dde | 5297 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
5298 | /* |
5299 | * ideally we don't want subsystems moving around while we do this. | |
5300 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
5301 | * subsys/hierarchy state. | |
5302 | */ | |
a424316c | 5303 | mutex_lock(&cgroup_mutex); |
30159ec7 TH |
5304 | |
5305 | for_each_subsys(ss, i) | |
2c6ab6d2 | 5306 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
3e1d2eed | 5307 | ss->legacy_name, ss->root->hierarchy_id, |
fc5ed1e9 TH |
5308 | atomic_read(&ss->root->nr_cgrps), |
5309 | cgroup_ssid_enabled(i)); | |
30159ec7 | 5310 | |
a424316c PM |
5311 | mutex_unlock(&cgroup_mutex); |
5312 | return 0; | |
5313 | } | |
5314 | ||
5315 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
5316 | { | |
9dce07f1 | 5317 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
5318 | } |
5319 | ||
828c0950 | 5320 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
5321 | .open = cgroupstats_open, |
5322 | .read = seq_read, | |
5323 | .llseek = seq_lseek, | |
5324 | .release = single_release, | |
5325 | }; | |
5326 | ||
7e47682e AS |
5327 | static void **subsys_canfork_priv_p(void *ss_priv[CGROUP_CANFORK_COUNT], int i) |
5328 | { | |
5329 | if (CGROUP_CANFORK_START <= i && i < CGROUP_CANFORK_END) | |
5330 | return &ss_priv[i - CGROUP_CANFORK_START]; | |
5331 | return NULL; | |
5332 | } | |
5333 | ||
5334 | static void *subsys_canfork_priv(void *ss_priv[CGROUP_CANFORK_COUNT], int i) | |
5335 | { | |
5336 | void **private = subsys_canfork_priv_p(ss_priv, i); | |
5337 | return private ? *private : NULL; | |
5338 | } | |
5339 | ||
b4f48b63 | 5340 | /** |
eaf797ab | 5341 | * cgroup_fork - initialize cgroup related fields during copy_process() |
a043e3b2 | 5342 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 | 5343 | * |
eaf797ab TH |
5344 | * A task is associated with the init_css_set until cgroup_post_fork() |
5345 | * attaches it to the parent's css_set. Empty cg_list indicates that | |
5346 | * @child isn't holding reference to its css_set. | |
b4f48b63 PM |
5347 | */ |
5348 | void cgroup_fork(struct task_struct *child) | |
5349 | { | |
eaf797ab | 5350 | RCU_INIT_POINTER(child->cgroups, &init_css_set); |
817929ec | 5351 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
5352 | } |
5353 | ||
7e47682e AS |
5354 | /** |
5355 | * cgroup_can_fork - called on a new task before the process is exposed | |
5356 | * @child: the task in question. | |
5357 | * | |
5358 | * This calls the subsystem can_fork() callbacks. If the can_fork() callback | |
5359 | * returns an error, the fork aborts with that error code. This allows for | |
5360 | * a cgroup subsystem to conditionally allow or deny new forks. | |
5361 | */ | |
5362 | int cgroup_can_fork(struct task_struct *child, | |
5363 | void *ss_priv[CGROUP_CANFORK_COUNT]) | |
5364 | { | |
5365 | struct cgroup_subsys *ss; | |
5366 | int i, j, ret; | |
5367 | ||
5368 | for_each_subsys_which(ss, i, &have_canfork_callback) { | |
5369 | ret = ss->can_fork(child, subsys_canfork_priv_p(ss_priv, i)); | |
5370 | if (ret) | |
5371 | goto out_revert; | |
5372 | } | |
5373 | ||
5374 | return 0; | |
5375 | ||
5376 | out_revert: | |
5377 | for_each_subsys(ss, j) { | |
5378 | if (j >= i) | |
5379 | break; | |
5380 | if (ss->cancel_fork) | |
5381 | ss->cancel_fork(child, subsys_canfork_priv(ss_priv, j)); | |
5382 | } | |
5383 | ||
5384 | return ret; | |
5385 | } | |
5386 | ||
5387 | /** | |
5388 | * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork() | |
5389 | * @child: the task in question | |
5390 | * | |
5391 | * This calls the cancel_fork() callbacks if a fork failed *after* | |
5392 | * cgroup_can_fork() succeded. | |
5393 | */ | |
5394 | void cgroup_cancel_fork(struct task_struct *child, | |
5395 | void *ss_priv[CGROUP_CANFORK_COUNT]) | |
5396 | { | |
5397 | struct cgroup_subsys *ss; | |
5398 | int i; | |
5399 | ||
5400 | for_each_subsys(ss, i) | |
5401 | if (ss->cancel_fork) | |
5402 | ss->cancel_fork(child, subsys_canfork_priv(ss_priv, i)); | |
5403 | } | |
5404 | ||
817929ec | 5405 | /** |
a043e3b2 LZ |
5406 | * cgroup_post_fork - called on a new task after adding it to the task list |
5407 | * @child: the task in question | |
5408 | * | |
5edee61e TH |
5409 | * Adds the task to the list running through its css_set if necessary and |
5410 | * call the subsystem fork() callbacks. Has to be after the task is | |
5411 | * visible on the task list in case we race with the first call to | |
0942eeee | 5412 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its |
5edee61e | 5413 | * list. |
a043e3b2 | 5414 | */ |
7e47682e AS |
5415 | void cgroup_post_fork(struct task_struct *child, |
5416 | void *old_ss_priv[CGROUP_CANFORK_COUNT]) | |
817929ec | 5417 | { |
30159ec7 | 5418 | struct cgroup_subsys *ss; |
5edee61e TH |
5419 | int i; |
5420 | ||
3ce3230a | 5421 | /* |
251f8c03 | 5422 | * This may race against cgroup_enable_task_cg_lists(). As that |
eaf797ab TH |
5423 | * function sets use_task_css_set_links before grabbing |
5424 | * tasklist_lock and we just went through tasklist_lock to add | |
5425 | * @child, it's guaranteed that either we see the set | |
5426 | * use_task_css_set_links or cgroup_enable_task_cg_lists() sees | |
5427 | * @child during its iteration. | |
5428 | * | |
5429 | * If we won the race, @child is associated with %current's | |
5430 | * css_set. Grabbing css_set_rwsem guarantees both that the | |
5431 | * association is stable, and, on completion of the parent's | |
5432 | * migration, @child is visible in the source of migration or | |
5433 | * already in the destination cgroup. This guarantee is necessary | |
5434 | * when implementing operations which need to migrate all tasks of | |
5435 | * a cgroup to another. | |
5436 | * | |
251f8c03 | 5437 | * Note that if we lose to cgroup_enable_task_cg_lists(), @child |
eaf797ab TH |
5438 | * will remain in init_css_set. This is safe because all tasks are |
5439 | * in the init_css_set before cg_links is enabled and there's no | |
5440 | * operation which transfers all tasks out of init_css_set. | |
3ce3230a | 5441 | */ |
817929ec | 5442 | if (use_task_css_set_links) { |
eaf797ab TH |
5443 | struct css_set *cset; |
5444 | ||
96d365e0 | 5445 | down_write(&css_set_rwsem); |
0e1d768f | 5446 | cset = task_css_set(current); |
eaf797ab TH |
5447 | if (list_empty(&child->cg_list)) { |
5448 | rcu_assign_pointer(child->cgroups, cset); | |
5449 | list_add(&child->cg_list, &cset->tasks); | |
5450 | get_css_set(cset); | |
5451 | } | |
96d365e0 | 5452 | up_write(&css_set_rwsem); |
817929ec | 5453 | } |
5edee61e TH |
5454 | |
5455 | /* | |
5456 | * Call ss->fork(). This must happen after @child is linked on | |
5457 | * css_set; otherwise, @child might change state between ->fork() | |
5458 | * and addition to css_set. | |
5459 | */ | |
cb4a3167 | 5460 | for_each_subsys_which(ss, i, &have_fork_callback) |
7e47682e | 5461 | ss->fork(child, subsys_canfork_priv(old_ss_priv, i)); |
817929ec | 5462 | } |
5edee61e | 5463 | |
b4f48b63 PM |
5464 | /** |
5465 | * cgroup_exit - detach cgroup from exiting task | |
5466 | * @tsk: pointer to task_struct of exiting process | |
5467 | * | |
5468 | * Description: Detach cgroup from @tsk and release it. | |
5469 | * | |
5470 | * Note that cgroups marked notify_on_release force every task in | |
5471 | * them to take the global cgroup_mutex mutex when exiting. | |
5472 | * This could impact scaling on very large systems. Be reluctant to | |
5473 | * use notify_on_release cgroups where very high task exit scaling | |
5474 | * is required on large systems. | |
5475 | * | |
0e1d768f TH |
5476 | * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We |
5477 | * call cgroup_exit() while the task is still competent to handle | |
5478 | * notify_on_release(), then leave the task attached to the root cgroup in | |
5479 | * each hierarchy for the remainder of its exit. No need to bother with | |
5480 | * init_css_set refcnting. init_css_set never goes away and we can't race | |
e8604cb4 | 5481 | * with migration path - PF_EXITING is visible to migration path. |
b4f48b63 | 5482 | */ |
1ec41830 | 5483 | void cgroup_exit(struct task_struct *tsk) |
b4f48b63 | 5484 | { |
30159ec7 | 5485 | struct cgroup_subsys *ss; |
5abb8855 | 5486 | struct css_set *cset; |
eaf797ab | 5487 | bool put_cset = false; |
d41d5a01 | 5488 | int i; |
817929ec PM |
5489 | |
5490 | /* | |
0e1d768f TH |
5491 | * Unlink from @tsk from its css_set. As migration path can't race |
5492 | * with us, we can check cg_list without grabbing css_set_rwsem. | |
817929ec PM |
5493 | */ |
5494 | if (!list_empty(&tsk->cg_list)) { | |
96d365e0 | 5495 | down_write(&css_set_rwsem); |
0e1d768f | 5496 | list_del_init(&tsk->cg_list); |
96d365e0 | 5497 | up_write(&css_set_rwsem); |
0e1d768f | 5498 | put_cset = true; |
817929ec PM |
5499 | } |
5500 | ||
b4f48b63 | 5501 | /* Reassign the task to the init_css_set. */ |
a8ad805c TH |
5502 | cset = task_css_set(tsk); |
5503 | RCU_INIT_POINTER(tsk->cgroups, &init_css_set); | |
d41d5a01 | 5504 | |
cb4a3167 AS |
5505 | /* see cgroup_post_fork() for details */ |
5506 | for_each_subsys_which(ss, i, &have_exit_callback) { | |
5507 | struct cgroup_subsys_state *old_css = cset->subsys[i]; | |
5508 | struct cgroup_subsys_state *css = task_css(tsk, i); | |
30159ec7 | 5509 | |
cb4a3167 | 5510 | ss->exit(css, old_css, tsk); |
d41d5a01 | 5511 | } |
d41d5a01 | 5512 | |
eaf797ab | 5513 | if (put_cset) |
a25eb52e | 5514 | put_css_set(cset); |
b4f48b63 | 5515 | } |
697f4161 | 5516 | |
bd89aabc | 5517 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd | 5518 | { |
a25eb52e | 5519 | if (notify_on_release(cgrp) && !cgroup_has_tasks(cgrp) && |
971ff493 ZL |
5520 | !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp)) |
5521 | schedule_work(&cgrp->release_agent_work); | |
81a6a5cd PM |
5522 | } |
5523 | ||
81a6a5cd PM |
5524 | /* |
5525 | * Notify userspace when a cgroup is released, by running the | |
5526 | * configured release agent with the name of the cgroup (path | |
5527 | * relative to the root of cgroup file system) as the argument. | |
5528 | * | |
5529 | * Most likely, this user command will try to rmdir this cgroup. | |
5530 | * | |
5531 | * This races with the possibility that some other task will be | |
5532 | * attached to this cgroup before it is removed, or that some other | |
5533 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
5534 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
5535 | * unused, and this cgroup will be reprieved from its death sentence, | |
5536 | * to continue to serve a useful existence. Next time it's released, | |
5537 | * we will get notified again, if it still has 'notify_on_release' set. | |
5538 | * | |
5539 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
5540 | * means only wait until the task is successfully execve()'d. The | |
5541 | * separate release agent task is forked by call_usermodehelper(), | |
5542 | * then control in this thread returns here, without waiting for the | |
5543 | * release agent task. We don't bother to wait because the caller of | |
5544 | * this routine has no use for the exit status of the release agent | |
5545 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 5546 | */ |
81a6a5cd PM |
5547 | static void cgroup_release_agent(struct work_struct *work) |
5548 | { | |
971ff493 ZL |
5549 | struct cgroup *cgrp = |
5550 | container_of(work, struct cgroup, release_agent_work); | |
5551 | char *pathbuf = NULL, *agentbuf = NULL, *path; | |
5552 | char *argv[3], *envp[3]; | |
5553 | ||
81a6a5cd | 5554 | mutex_lock(&cgroup_mutex); |
971ff493 ZL |
5555 | |
5556 | pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); | |
5557 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
5558 | if (!pathbuf || !agentbuf) | |
5559 | goto out; | |
5560 | ||
5561 | path = cgroup_path(cgrp, pathbuf, PATH_MAX); | |
5562 | if (!path) | |
5563 | goto out; | |
5564 | ||
5565 | argv[0] = agentbuf; | |
5566 | argv[1] = path; | |
5567 | argv[2] = NULL; | |
5568 | ||
5569 | /* minimal command environment */ | |
5570 | envp[0] = "HOME=/"; | |
5571 | envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
5572 | envp[2] = NULL; | |
5573 | ||
81a6a5cd | 5574 | mutex_unlock(&cgroup_mutex); |
971ff493 | 5575 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); |
3e2cd91a | 5576 | goto out_free; |
971ff493 | 5577 | out: |
81a6a5cd | 5578 | mutex_unlock(&cgroup_mutex); |
3e2cd91a | 5579 | out_free: |
971ff493 ZL |
5580 | kfree(agentbuf); |
5581 | kfree(pathbuf); | |
81a6a5cd | 5582 | } |
8bab8dde PM |
5583 | |
5584 | static int __init cgroup_disable(char *str) | |
5585 | { | |
30159ec7 | 5586 | struct cgroup_subsys *ss; |
8bab8dde | 5587 | char *token; |
30159ec7 | 5588 | int i; |
8bab8dde PM |
5589 | |
5590 | while ((token = strsep(&str, ",")) != NULL) { | |
5591 | if (!*token) | |
5592 | continue; | |
be45c900 | 5593 | |
3ed80a62 | 5594 | for_each_subsys(ss, i) { |
3e1d2eed TH |
5595 | if (strcmp(token, ss->name) && |
5596 | strcmp(token, ss->legacy_name)) | |
5597 | continue; | |
5598 | ||
49d1dc4b | 5599 | static_branch_disable(cgroup_subsys_enabled_key[i]); |
3e1d2eed TH |
5600 | printk(KERN_INFO "Disabling %s control group subsystem\n", |
5601 | ss->name); | |
5602 | break; | |
8bab8dde PM |
5603 | } |
5604 | } | |
5605 | return 1; | |
5606 | } | |
5607 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 | 5608 | |
a8ddc821 TH |
5609 | static int __init cgroup_set_legacy_files_on_dfl(char *str) |
5610 | { | |
5611 | printk("cgroup: using legacy files on the default hierarchy\n"); | |
5612 | cgroup_legacy_files_on_dfl = true; | |
5613 | return 0; | |
5614 | } | |
5615 | __setup("cgroup__DEVEL__legacy_files_on_dfl", cgroup_set_legacy_files_on_dfl); | |
5616 | ||
b77d7b60 | 5617 | /** |
ec903c0c | 5618 | * css_tryget_online_from_dir - get corresponding css from a cgroup dentry |
35cf0836 TH |
5619 | * @dentry: directory dentry of interest |
5620 | * @ss: subsystem of interest | |
b77d7b60 | 5621 | * |
5a17f543 TH |
5622 | * If @dentry is a directory for a cgroup which has @ss enabled on it, try |
5623 | * to get the corresponding css and return it. If such css doesn't exist | |
5624 | * or can't be pinned, an ERR_PTR value is returned. | |
e5d1367f | 5625 | */ |
ec903c0c TH |
5626 | struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, |
5627 | struct cgroup_subsys *ss) | |
e5d1367f | 5628 | { |
2bd59d48 TH |
5629 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
5630 | struct cgroup_subsys_state *css = NULL; | |
e5d1367f | 5631 | struct cgroup *cgrp; |
e5d1367f | 5632 | |
35cf0836 | 5633 | /* is @dentry a cgroup dir? */ |
2bd59d48 TH |
5634 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || |
5635 | kernfs_type(kn) != KERNFS_DIR) | |
e5d1367f SE |
5636 | return ERR_PTR(-EBADF); |
5637 | ||
5a17f543 TH |
5638 | rcu_read_lock(); |
5639 | ||
2bd59d48 TH |
5640 | /* |
5641 | * This path doesn't originate from kernfs and @kn could already | |
5642 | * have been or be removed at any point. @kn->priv is RCU | |
a4189487 | 5643 | * protected for this access. See css_release_work_fn() for details. |
2bd59d48 TH |
5644 | */ |
5645 | cgrp = rcu_dereference(kn->priv); | |
5646 | if (cgrp) | |
5647 | css = cgroup_css(cgrp, ss); | |
5a17f543 | 5648 | |
ec903c0c | 5649 | if (!css || !css_tryget_online(css)) |
5a17f543 TH |
5650 | css = ERR_PTR(-ENOENT); |
5651 | ||
5652 | rcu_read_unlock(); | |
5653 | return css; | |
e5d1367f | 5654 | } |
e5d1367f | 5655 | |
1cb650b9 LZ |
5656 | /** |
5657 | * css_from_id - lookup css by id | |
5658 | * @id: the cgroup id | |
5659 | * @ss: cgroup subsys to be looked into | |
5660 | * | |
5661 | * Returns the css if there's valid one with @id, otherwise returns NULL. | |
5662 | * Should be called under rcu_read_lock(). | |
5663 | */ | |
5664 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) | |
5665 | { | |
6fa4918d | 5666 | WARN_ON_ONCE(!rcu_read_lock_held()); |
adbe427b | 5667 | return id > 0 ? idr_find(&ss->css_idr, id) : NULL; |
e5d1367f SE |
5668 | } |
5669 | ||
fe693435 | 5670 | #ifdef CONFIG_CGROUP_DEBUG |
eb95419b TH |
5671 | static struct cgroup_subsys_state * |
5672 | debug_css_alloc(struct cgroup_subsys_state *parent_css) | |
fe693435 PM |
5673 | { |
5674 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5675 | ||
5676 | if (!css) | |
5677 | return ERR_PTR(-ENOMEM); | |
5678 | ||
5679 | return css; | |
5680 | } | |
5681 | ||
eb95419b | 5682 | static void debug_css_free(struct cgroup_subsys_state *css) |
fe693435 | 5683 | { |
eb95419b | 5684 | kfree(css); |
fe693435 PM |
5685 | } |
5686 | ||
182446d0 TH |
5687 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
5688 | struct cftype *cft) | |
fe693435 | 5689 | { |
182446d0 | 5690 | return cgroup_task_count(css->cgroup); |
fe693435 PM |
5691 | } |
5692 | ||
182446d0 TH |
5693 | static u64 current_css_set_read(struct cgroup_subsys_state *css, |
5694 | struct cftype *cft) | |
fe693435 PM |
5695 | { |
5696 | return (u64)(unsigned long)current->cgroups; | |
5697 | } | |
5698 | ||
182446d0 | 5699 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
03c78cbe | 5700 | struct cftype *cft) |
fe693435 PM |
5701 | { |
5702 | u64 count; | |
5703 | ||
5704 | rcu_read_lock(); | |
a8ad805c | 5705 | count = atomic_read(&task_css_set(current)->refcount); |
fe693435 PM |
5706 | rcu_read_unlock(); |
5707 | return count; | |
5708 | } | |
5709 | ||
2da8ca82 | 5710 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
7717f7ba | 5711 | { |
69d0206c | 5712 | struct cgrp_cset_link *link; |
5abb8855 | 5713 | struct css_set *cset; |
e61734c5 TH |
5714 | char *name_buf; |
5715 | ||
5716 | name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
5717 | if (!name_buf) | |
5718 | return -ENOMEM; | |
7717f7ba | 5719 | |
96d365e0 | 5720 | down_read(&css_set_rwsem); |
7717f7ba | 5721 | rcu_read_lock(); |
5abb8855 | 5722 | cset = rcu_dereference(current->cgroups); |
69d0206c | 5723 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
7717f7ba | 5724 | struct cgroup *c = link->cgrp; |
7717f7ba | 5725 | |
a2dd4247 | 5726 | cgroup_name(c, name_buf, NAME_MAX + 1); |
2c6ab6d2 | 5727 | seq_printf(seq, "Root %d group %s\n", |
a2dd4247 | 5728 | c->root->hierarchy_id, name_buf); |
7717f7ba PM |
5729 | } |
5730 | rcu_read_unlock(); | |
96d365e0 | 5731 | up_read(&css_set_rwsem); |
e61734c5 | 5732 | kfree(name_buf); |
7717f7ba PM |
5733 | return 0; |
5734 | } | |
5735 | ||
5736 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
2da8ca82 | 5737 | static int cgroup_css_links_read(struct seq_file *seq, void *v) |
7717f7ba | 5738 | { |
2da8ca82 | 5739 | struct cgroup_subsys_state *css = seq_css(seq); |
69d0206c | 5740 | struct cgrp_cset_link *link; |
7717f7ba | 5741 | |
96d365e0 | 5742 | down_read(&css_set_rwsem); |
182446d0 | 5743 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
69d0206c | 5744 | struct css_set *cset = link->cset; |
7717f7ba PM |
5745 | struct task_struct *task; |
5746 | int count = 0; | |
c7561128 | 5747 | |
5abb8855 | 5748 | seq_printf(seq, "css_set %p\n", cset); |
c7561128 | 5749 | |
5abb8855 | 5750 | list_for_each_entry(task, &cset->tasks, cg_list) { |
c7561128 TH |
5751 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
5752 | goto overflow; | |
5753 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
5754 | } | |
5755 | ||
5756 | list_for_each_entry(task, &cset->mg_tasks, cg_list) { | |
5757 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) | |
5758 | goto overflow; | |
5759 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
7717f7ba | 5760 | } |
c7561128 TH |
5761 | continue; |
5762 | overflow: | |
5763 | seq_puts(seq, " ...\n"); | |
7717f7ba | 5764 | } |
96d365e0 | 5765 | up_read(&css_set_rwsem); |
7717f7ba PM |
5766 | return 0; |
5767 | } | |
5768 | ||
182446d0 | 5769 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
fe693435 | 5770 | { |
a25eb52e ZL |
5771 | return (!cgroup_has_tasks(css->cgroup) && |
5772 | !css_has_online_children(&css->cgroup->self)); | |
fe693435 PM |
5773 | } |
5774 | ||
5775 | static struct cftype debug_files[] = { | |
fe693435 PM |
5776 | { |
5777 | .name = "taskcount", | |
5778 | .read_u64 = debug_taskcount_read, | |
5779 | }, | |
5780 | ||
5781 | { | |
5782 | .name = "current_css_set", | |
5783 | .read_u64 = current_css_set_read, | |
5784 | }, | |
5785 | ||
5786 | { | |
5787 | .name = "current_css_set_refcount", | |
5788 | .read_u64 = current_css_set_refcount_read, | |
5789 | }, | |
5790 | ||
7717f7ba PM |
5791 | { |
5792 | .name = "current_css_set_cg_links", | |
2da8ca82 | 5793 | .seq_show = current_css_set_cg_links_read, |
7717f7ba PM |
5794 | }, |
5795 | ||
5796 | { | |
5797 | .name = "cgroup_css_links", | |
2da8ca82 | 5798 | .seq_show = cgroup_css_links_read, |
7717f7ba PM |
5799 | }, |
5800 | ||
fe693435 PM |
5801 | { |
5802 | .name = "releasable", | |
5803 | .read_u64 = releasable_read, | |
5804 | }, | |
fe693435 | 5805 | |
4baf6e33 TH |
5806 | { } /* terminate */ |
5807 | }; | |
fe693435 | 5808 | |
073219e9 | 5809 | struct cgroup_subsys debug_cgrp_subsys = { |
92fb9748 TH |
5810 | .css_alloc = debug_css_alloc, |
5811 | .css_free = debug_css_free, | |
5577964e | 5812 | .legacy_cftypes = debug_files, |
fe693435 PM |
5813 | }; |
5814 | #endif /* CONFIG_CGROUP_DEBUG */ |