2 * Generic process-grouping system.
4 * Based originally on the cpuset system, extracted by Paul Menage
5 * Copyright (C) 2006 Google, Inc
7 * Copyright notices from the original cpuset code:
8 * --------------------------------------------------
9 * Copyright (C) 2003 BULL SA.
10 * Copyright (C) 2004-2006 Silicon Graphics, Inc.
12 * Portions derived from Patrick Mochel's sysfs code.
13 * sysfs is Copyright (c) 2001-3 Patrick Mochel
15 * 2003-10-10 Written by Simon Derr.
16 * 2003-10-22 Updates by Stephen Hemminger.
17 * 2004 May-July Rework by Paul Jackson.
18 * ---------------------------------------------------
20 * This file is subject to the terms and conditions of the GNU General Public
21 * License. See the file COPYING in the main directory of the Linux
22 * distribution for more details.
25 #include <linux/cgroup.h>
26 #include <linux/module.h>
27 #include <linux/ctype.h>
28 #include <linux/errno.h>
30 #include <linux/kernel.h>
31 #include <linux/list.h>
33 #include <linux/mutex.h>
34 #include <linux/mount.h>
35 #include <linux/pagemap.h>
36 #include <linux/proc_fs.h>
37 #include <linux/rcupdate.h>
38 #include <linux/sched.h>
39 #include <linux/backing-dev.h>
40 #include <linux/seq_file.h>
41 #include <linux/slab.h>
42 #include <linux/magic.h>
43 #include <linux/spinlock.h>
44 #include <linux/string.h>
45 #include <linux/sort.h>
46 #include <linux/kmod.h>
47 #include <linux/delayacct.h>
48 #include <linux/cgroupstats.h>
49 #include <linux/hash.h>
50 #include <linux/namei.h>
51 #include <linux/smp_lock.h>
52 #include <linux/pid_namespace.h>
53 #include <linux/idr.h>
54 #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
56 #include <asm/atomic.h>
58 static DEFINE_MUTEX(cgroup_mutex
);
61 * Generate an array of cgroup subsystem pointers. At boot time, this is
62 * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are
63 * registered after that. The mutable section of this array is protected by
66 #define SUBSYS(_x) &_x ## _subsys,
67 static struct cgroup_subsys
*subsys
[CGROUP_SUBSYS_COUNT
] = {
68 #include <linux/cgroup_subsys.h>
71 #define MAX_CGROUP_ROOT_NAMELEN 64
74 * A cgroupfs_root represents the root of a cgroup hierarchy,
75 * and may be associated with a superblock to form an active
78 struct cgroupfs_root
{
79 struct super_block
*sb
;
82 * The bitmask of subsystems intended to be attached to this
85 unsigned long subsys_bits
;
87 /* Unique id for this hierarchy. */
90 /* The bitmask of subsystems currently attached to this hierarchy */
91 unsigned long actual_subsys_bits
;
93 /* A list running through the attached subsystems */
94 struct list_head subsys_list
;
96 /* The root cgroup for this hierarchy */
97 struct cgroup top_cgroup
;
99 /* Tracks how many cgroups are currently defined in hierarchy.*/
100 int number_of_cgroups
;
102 /* A list running through the active hierarchies */
103 struct list_head root_list
;
105 /* Hierarchy-specific flags */
108 /* The path to use for release notifications. */
109 char release_agent_path
[PATH_MAX
];
111 /* The name for this hierarchy - may be empty */
112 char name
[MAX_CGROUP_ROOT_NAMELEN
];
116 * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
117 * subsystems that are otherwise unattached - it never has more than a
118 * single cgroup, and all tasks are part of that cgroup.
120 static struct cgroupfs_root rootnode
;
123 * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
124 * cgroup_subsys->use_id != 0.
126 #define CSS_ID_MAX (65535)
129 * The css to which this ID points. This pointer is set to valid value
130 * after cgroup is populated. If cgroup is removed, this will be NULL.
131 * This pointer is expected to be RCU-safe because destroy()
132 * is called after synchronize_rcu(). But for safe use, css_is_removed()
133 * css_tryget() should be used for avoiding race.
135 struct cgroup_subsys_state
*css
;
141 * Depth in hierarchy which this ID belongs to.
143 unsigned short depth
;
145 * ID is freed by RCU. (and lookup routine is RCU safe.)
147 struct rcu_head rcu_head
;
149 * Hierarchy of CSS ID belongs to.
151 unsigned short stack
[0]; /* Array of Length (depth+1) */
155 /* The list of hierarchy roots */
157 static LIST_HEAD(roots
);
158 static int root_count
;
160 static DEFINE_IDA(hierarchy_ida
);
161 static int next_hierarchy_id
;
162 static DEFINE_SPINLOCK(hierarchy_id_lock
);
164 /* dummytop is a shorthand for the dummy hierarchy's top cgroup */
165 #define dummytop (&rootnode.top_cgroup)
167 /* This flag indicates whether tasks in the fork and exit paths should
168 * check for fork/exit handlers to call. This avoids us having to do
169 * extra work in the fork/exit path if none of the subsystems need to
172 static int need_forkexit_callback __read_mostly
;
174 #ifdef CONFIG_PROVE_LOCKING
175 int cgroup_lock_is_held(void)
177 return lockdep_is_held(&cgroup_mutex
);
179 #else /* #ifdef CONFIG_PROVE_LOCKING */
180 int cgroup_lock_is_held(void)
182 return mutex_is_locked(&cgroup_mutex
);
184 #endif /* #else #ifdef CONFIG_PROVE_LOCKING */
186 EXPORT_SYMBOL_GPL(cgroup_lock_is_held
);
188 /* convenient tests for these bits */
189 inline int cgroup_is_removed(const struct cgroup
*cgrp
)
191 return test_bit(CGRP_REMOVED
, &cgrp
->flags
);
194 /* bits in struct cgroupfs_root flags field */
196 ROOT_NOPREFIX
, /* mounted subsystems have no named prefix */
199 static int cgroup_is_releasable(const struct cgroup
*cgrp
)
202 (1 << CGRP_RELEASABLE
) |
203 (1 << CGRP_NOTIFY_ON_RELEASE
);
204 return (cgrp
->flags
& bits
) == bits
;
207 static int notify_on_release(const struct cgroup
*cgrp
)
209 return test_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
213 * for_each_subsys() allows you to iterate on each subsystem attached to
214 * an active hierarchy
216 #define for_each_subsys(_root, _ss) \
217 list_for_each_entry(_ss, &_root->subsys_list, sibling)
219 /* for_each_active_root() allows you to iterate across the active hierarchies */
220 #define for_each_active_root(_root) \
221 list_for_each_entry(_root, &roots, root_list)
223 /* the list of cgroups eligible for automatic release. Protected by
224 * release_list_lock */
225 static LIST_HEAD(release_list
);
226 static DEFINE_SPINLOCK(release_list_lock
);
227 static void cgroup_release_agent(struct work_struct
*work
);
228 static DECLARE_WORK(release_agent_work
, cgroup_release_agent
);
229 static void check_for_release(struct cgroup
*cgrp
);
231 /* Link structure for associating css_set objects with cgroups */
232 struct cg_cgroup_link
{
234 * List running through cg_cgroup_links associated with a
235 * cgroup, anchored on cgroup->css_sets
237 struct list_head cgrp_link_list
;
240 * List running through cg_cgroup_links pointing at a
241 * single css_set object, anchored on css_set->cg_links
243 struct list_head cg_link_list
;
247 /* The default css_set - used by init and its children prior to any
248 * hierarchies being mounted. It contains a pointer to the root state
249 * for each subsystem. Also used to anchor the list of css_sets. Not
250 * reference-counted, to improve performance when child cgroups
251 * haven't been created.
254 static struct css_set init_css_set
;
255 static struct cg_cgroup_link init_css_set_link
;
257 static int cgroup_subsys_init_idr(struct cgroup_subsys
*ss
);
259 /* css_set_lock protects the list of css_set objects, and the
260 * chain of tasks off each css_set. Nests outside task->alloc_lock
261 * due to cgroup_iter_start() */
262 static DEFINE_RWLOCK(css_set_lock
);
263 static int css_set_count
;
266 * hash table for cgroup groups. This improves the performance to find
267 * an existing css_set. This hash doesn't (currently) take into
268 * account cgroups in empty hierarchies.
270 #define CSS_SET_HASH_BITS 7
271 #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS)
272 static struct hlist_head css_set_table
[CSS_SET_TABLE_SIZE
];
274 static struct hlist_head
*css_set_hash(struct cgroup_subsys_state
*css
[])
278 unsigned long tmp
= 0UL;
280 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++)
281 tmp
+= (unsigned long)css
[i
];
282 tmp
= (tmp
>> 16) ^ tmp
;
284 index
= hash_long(tmp
, CSS_SET_HASH_BITS
);
286 return &css_set_table
[index
];
289 static void free_css_set_rcu(struct rcu_head
*obj
)
291 struct css_set
*cg
= container_of(obj
, struct css_set
, rcu_head
);
295 /* We don't maintain the lists running through each css_set to its
296 * task until after the first call to cgroup_iter_start(). This
297 * reduces the fork()/exit() overhead for people who have cgroups
298 * compiled into their kernel but not actually in use */
299 static int use_task_css_set_links __read_mostly
;
301 static void __put_css_set(struct css_set
*cg
, int taskexit
)
303 struct cg_cgroup_link
*link
;
304 struct cg_cgroup_link
*saved_link
;
306 * Ensure that the refcount doesn't hit zero while any readers
307 * can see it. Similar to atomic_dec_and_lock(), but for an
310 if (atomic_add_unless(&cg
->refcount
, -1, 1))
312 write_lock(&css_set_lock
);
313 if (!atomic_dec_and_test(&cg
->refcount
)) {
314 write_unlock(&css_set_lock
);
318 /* This css_set is dead. unlink it and release cgroup refcounts */
319 hlist_del(&cg
->hlist
);
322 list_for_each_entry_safe(link
, saved_link
, &cg
->cg_links
,
324 struct cgroup
*cgrp
= link
->cgrp
;
325 list_del(&link
->cg_link_list
);
326 list_del(&link
->cgrp_link_list
);
327 if (atomic_dec_and_test(&cgrp
->count
) &&
328 notify_on_release(cgrp
)) {
330 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
331 check_for_release(cgrp
);
337 write_unlock(&css_set_lock
);
338 call_rcu(&cg
->rcu_head
, free_css_set_rcu
);
342 * refcounted get/put for css_set objects
344 static inline void get_css_set(struct css_set
*cg
)
346 atomic_inc(&cg
->refcount
);
349 static inline void put_css_set(struct css_set
*cg
)
351 __put_css_set(cg
, 0);
354 static inline void put_css_set_taskexit(struct css_set
*cg
)
356 __put_css_set(cg
, 1);
360 * compare_css_sets - helper function for find_existing_css_set().
361 * @cg: candidate css_set being tested
362 * @old_cg: existing css_set for a task
363 * @new_cgrp: cgroup that's being entered by the task
364 * @template: desired set of css pointers in css_set (pre-calculated)
366 * Returns true if "cg" matches "old_cg" except for the hierarchy
367 * which "new_cgrp" belongs to, for which it should match "new_cgrp".
369 static bool compare_css_sets(struct css_set
*cg
,
370 struct css_set
*old_cg
,
371 struct cgroup
*new_cgrp
,
372 struct cgroup_subsys_state
*template[])
374 struct list_head
*l1
, *l2
;
376 if (memcmp(template, cg
->subsys
, sizeof(cg
->subsys
))) {
377 /* Not all subsystems matched */
382 * Compare cgroup pointers in order to distinguish between
383 * different cgroups in heirarchies with no subsystems. We
384 * could get by with just this check alone (and skip the
385 * memcmp above) but on most setups the memcmp check will
386 * avoid the need for this more expensive check on almost all
391 l2
= &old_cg
->cg_links
;
393 struct cg_cgroup_link
*cgl1
, *cgl2
;
394 struct cgroup
*cg1
, *cg2
;
398 /* See if we reached the end - both lists are equal length. */
399 if (l1
== &cg
->cg_links
) {
400 BUG_ON(l2
!= &old_cg
->cg_links
);
403 BUG_ON(l2
== &old_cg
->cg_links
);
405 /* Locate the cgroups associated with these links. */
406 cgl1
= list_entry(l1
, struct cg_cgroup_link
, cg_link_list
);
407 cgl2
= list_entry(l2
, struct cg_cgroup_link
, cg_link_list
);
410 /* Hierarchies should be linked in the same order. */
411 BUG_ON(cg1
->root
!= cg2
->root
);
414 * If this hierarchy is the hierarchy of the cgroup
415 * that's changing, then we need to check that this
416 * css_set points to the new cgroup; if it's any other
417 * hierarchy, then this css_set should point to the
418 * same cgroup as the old css_set.
420 if (cg1
->root
== new_cgrp
->root
) {
432 * find_existing_css_set() is a helper for
433 * find_css_set(), and checks to see whether an existing
434 * css_set is suitable.
436 * oldcg: the cgroup group that we're using before the cgroup
439 * cgrp: the cgroup that we're moving into
441 * template: location in which to build the desired set of subsystem
442 * state objects for the new cgroup group
444 static struct css_set
*find_existing_css_set(
445 struct css_set
*oldcg
,
447 struct cgroup_subsys_state
*template[])
450 struct cgroupfs_root
*root
= cgrp
->root
;
451 struct hlist_head
*hhead
;
452 struct hlist_node
*node
;
456 * Build the set of subsystem state objects that we want to see in the
457 * new css_set. while subsystems can change globally, the entries here
458 * won't change, so no need for locking.
460 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
461 if (root
->subsys_bits
& (1UL << i
)) {
462 /* Subsystem is in this hierarchy. So we want
463 * the subsystem state from the new
465 template[i
] = cgrp
->subsys
[i
];
467 /* Subsystem is not in this hierarchy, so we
468 * don't want to change the subsystem state */
469 template[i
] = oldcg
->subsys
[i
];
473 hhead
= css_set_hash(template);
474 hlist_for_each_entry(cg
, node
, hhead
, hlist
) {
475 if (!compare_css_sets(cg
, oldcg
, cgrp
, template))
478 /* This css_set matches what we need */
482 /* No existing cgroup group matched */
486 static void free_cg_links(struct list_head
*tmp
)
488 struct cg_cgroup_link
*link
;
489 struct cg_cgroup_link
*saved_link
;
491 list_for_each_entry_safe(link
, saved_link
, tmp
, cgrp_link_list
) {
492 list_del(&link
->cgrp_link_list
);
498 * allocate_cg_links() allocates "count" cg_cgroup_link structures
499 * and chains them on tmp through their cgrp_link_list fields. Returns 0 on
500 * success or a negative error
502 static int allocate_cg_links(int count
, struct list_head
*tmp
)
504 struct cg_cgroup_link
*link
;
507 for (i
= 0; i
< count
; i
++) {
508 link
= kmalloc(sizeof(*link
), GFP_KERNEL
);
513 list_add(&link
->cgrp_link_list
, tmp
);
519 * link_css_set - a helper function to link a css_set to a cgroup
520 * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links()
521 * @cg: the css_set to be linked
522 * @cgrp: the destination cgroup
524 static void link_css_set(struct list_head
*tmp_cg_links
,
525 struct css_set
*cg
, struct cgroup
*cgrp
)
527 struct cg_cgroup_link
*link
;
529 BUG_ON(list_empty(tmp_cg_links
));
530 link
= list_first_entry(tmp_cg_links
, struct cg_cgroup_link
,
534 atomic_inc(&cgrp
->count
);
535 list_move(&link
->cgrp_link_list
, &cgrp
->css_sets
);
537 * Always add links to the tail of the list so that the list
538 * is sorted by order of hierarchy creation
540 list_add_tail(&link
->cg_link_list
, &cg
->cg_links
);
544 * find_css_set() takes an existing cgroup group and a
545 * cgroup object, and returns a css_set object that's
546 * equivalent to the old group, but with the given cgroup
547 * substituted into the appropriate hierarchy. Must be called with
550 static struct css_set
*find_css_set(
551 struct css_set
*oldcg
, struct cgroup
*cgrp
)
554 struct cgroup_subsys_state
*template[CGROUP_SUBSYS_COUNT
];
556 struct list_head tmp_cg_links
;
558 struct hlist_head
*hhead
;
559 struct cg_cgroup_link
*link
;
561 /* First see if we already have a cgroup group that matches
563 read_lock(&css_set_lock
);
564 res
= find_existing_css_set(oldcg
, cgrp
, template);
567 read_unlock(&css_set_lock
);
572 res
= kmalloc(sizeof(*res
), GFP_KERNEL
);
576 /* Allocate all the cg_cgroup_link objects that we'll need */
577 if (allocate_cg_links(root_count
, &tmp_cg_links
) < 0) {
582 atomic_set(&res
->refcount
, 1);
583 INIT_LIST_HEAD(&res
->cg_links
);
584 INIT_LIST_HEAD(&res
->tasks
);
585 INIT_HLIST_NODE(&res
->hlist
);
587 /* Copy the set of subsystem state objects generated in
588 * find_existing_css_set() */
589 memcpy(res
->subsys
, template, sizeof(res
->subsys
));
591 write_lock(&css_set_lock
);
592 /* Add reference counts and links from the new css_set. */
593 list_for_each_entry(link
, &oldcg
->cg_links
, cg_link_list
) {
594 struct cgroup
*c
= link
->cgrp
;
595 if (c
->root
== cgrp
->root
)
597 link_css_set(&tmp_cg_links
, res
, c
);
600 BUG_ON(!list_empty(&tmp_cg_links
));
604 /* Add this cgroup group to the hash table */
605 hhead
= css_set_hash(res
->subsys
);
606 hlist_add_head(&res
->hlist
, hhead
);
608 write_unlock(&css_set_lock
);
614 * Return the cgroup for "task" from the given hierarchy. Must be
615 * called with cgroup_mutex held.
617 static struct cgroup
*task_cgroup_from_root(struct task_struct
*task
,
618 struct cgroupfs_root
*root
)
621 struct cgroup
*res
= NULL
;
623 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
624 read_lock(&css_set_lock
);
626 * No need to lock the task - since we hold cgroup_mutex the
627 * task can't change groups, so the only thing that can happen
628 * is that it exits and its css is set back to init_css_set.
631 if (css
== &init_css_set
) {
632 res
= &root
->top_cgroup
;
634 struct cg_cgroup_link
*link
;
635 list_for_each_entry(link
, &css
->cg_links
, cg_link_list
) {
636 struct cgroup
*c
= link
->cgrp
;
637 if (c
->root
== root
) {
643 read_unlock(&css_set_lock
);
649 * There is one global cgroup mutex. We also require taking
650 * task_lock() when dereferencing a task's cgroup subsys pointers.
651 * See "The task_lock() exception", at the end of this comment.
653 * A task must hold cgroup_mutex to modify cgroups.
655 * Any task can increment and decrement the count field without lock.
656 * So in general, code holding cgroup_mutex can't rely on the count
657 * field not changing. However, if the count goes to zero, then only
658 * cgroup_attach_task() can increment it again. Because a count of zero
659 * means that no tasks are currently attached, therefore there is no
660 * way a task attached to that cgroup can fork (the other way to
661 * increment the count). So code holding cgroup_mutex can safely
662 * assume that if the count is zero, it will stay zero. Similarly, if
663 * a task holds cgroup_mutex on a cgroup with zero count, it
664 * knows that the cgroup won't be removed, as cgroup_rmdir()
667 * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
668 * (usually) take cgroup_mutex. These are the two most performance
669 * critical pieces of code here. The exception occurs on cgroup_exit(),
670 * when a task in a notify_on_release cgroup exits. Then cgroup_mutex
671 * is taken, and if the cgroup count is zero, a usermode call made
672 * to the release agent with the name of the cgroup (path relative to
673 * the root of cgroup file system) as the argument.
675 * A cgroup can only be deleted if both its 'count' of using tasks
676 * is zero, and its list of 'children' cgroups is empty. Since all
677 * tasks in the system use _some_ cgroup, and since there is always at
678 * least one task in the system (init, pid == 1), therefore, top_cgroup
679 * always has either children cgroups and/or using tasks. So we don't
680 * need a special hack to ensure that top_cgroup cannot be deleted.
682 * The task_lock() exception
684 * The need for this exception arises from the action of
685 * cgroup_attach_task(), which overwrites one tasks cgroup pointer with
686 * another. It does so using cgroup_mutex, however there are
687 * several performance critical places that need to reference
688 * task->cgroup without the expense of grabbing a system global
689 * mutex. Therefore except as noted below, when dereferencing or, as
690 * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use
691 * task_lock(), which acts on a spinlock (task->alloc_lock) already in
692 * the task_struct routinely used for such matters.
694 * P.S. One more locking exception. RCU is used to guard the
695 * update of a tasks cgroup pointer by cgroup_attach_task()
699 * cgroup_lock - lock out any changes to cgroup structures
702 void cgroup_lock(void)
704 mutex_lock(&cgroup_mutex
);
708 * cgroup_unlock - release lock on cgroup changes
710 * Undo the lock taken in a previous cgroup_lock() call.
712 void cgroup_unlock(void)
714 mutex_unlock(&cgroup_mutex
);
718 * A couple of forward declarations required, due to cyclic reference loop:
719 * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
720 * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
724 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
);
725 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
);
726 static int cgroup_populate_dir(struct cgroup
*cgrp
);
727 static const struct inode_operations cgroup_dir_inode_operations
;
728 static const struct file_operations proc_cgroupstats_operations
;
730 static struct backing_dev_info cgroup_backing_dev_info
= {
732 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
,
735 static int alloc_css_id(struct cgroup_subsys
*ss
,
736 struct cgroup
*parent
, struct cgroup
*child
);
738 static struct inode
*cgroup_new_inode(mode_t mode
, struct super_block
*sb
)
740 struct inode
*inode
= new_inode(sb
);
743 inode
->i_mode
= mode
;
744 inode
->i_uid
= current_fsuid();
745 inode
->i_gid
= current_fsgid();
746 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
747 inode
->i_mapping
->backing_dev_info
= &cgroup_backing_dev_info
;
753 * Call subsys's pre_destroy handler.
754 * This is called before css refcnt check.
756 static int cgroup_call_pre_destroy(struct cgroup
*cgrp
)
758 struct cgroup_subsys
*ss
;
761 for_each_subsys(cgrp
->root
, ss
)
762 if (ss
->pre_destroy
) {
763 ret
= ss
->pre_destroy(ss
, cgrp
);
770 static void free_cgroup_rcu(struct rcu_head
*obj
)
772 struct cgroup
*cgrp
= container_of(obj
, struct cgroup
, rcu_head
);
777 static void cgroup_diput(struct dentry
*dentry
, struct inode
*inode
)
779 /* is dentry a directory ? if so, kfree() associated cgroup */
780 if (S_ISDIR(inode
->i_mode
)) {
781 struct cgroup
*cgrp
= dentry
->d_fsdata
;
782 struct cgroup_subsys
*ss
;
783 BUG_ON(!(cgroup_is_removed(cgrp
)));
784 /* It's possible for external users to be holding css
785 * reference counts on a cgroup; css_put() needs to
786 * be able to access the cgroup after decrementing
787 * the reference count in order to know if it needs to
788 * queue the cgroup to be handled by the release
792 mutex_lock(&cgroup_mutex
);
794 * Release the subsystem state objects.
796 for_each_subsys(cgrp
->root
, ss
)
797 ss
->destroy(ss
, cgrp
);
799 cgrp
->root
->number_of_cgroups
--;
800 mutex_unlock(&cgroup_mutex
);
803 * Drop the active superblock reference that we took when we
806 deactivate_super(cgrp
->root
->sb
);
809 * if we're getting rid of the cgroup, refcount should ensure
810 * that there are no pidlists left.
812 BUG_ON(!list_empty(&cgrp
->pidlists
));
814 call_rcu(&cgrp
->rcu_head
, free_cgroup_rcu
);
819 static void remove_dir(struct dentry
*d
)
821 struct dentry
*parent
= dget(d
->d_parent
);
824 simple_rmdir(parent
->d_inode
, d
);
828 static void cgroup_clear_directory(struct dentry
*dentry
)
830 struct list_head
*node
;
832 BUG_ON(!mutex_is_locked(&dentry
->d_inode
->i_mutex
));
833 spin_lock(&dcache_lock
);
834 node
= dentry
->d_subdirs
.next
;
835 while (node
!= &dentry
->d_subdirs
) {
836 struct dentry
*d
= list_entry(node
, struct dentry
, d_u
.d_child
);
839 /* This should never be called on a cgroup
840 * directory with child cgroups */
841 BUG_ON(d
->d_inode
->i_mode
& S_IFDIR
);
843 spin_unlock(&dcache_lock
);
845 simple_unlink(dentry
->d_inode
, d
);
847 spin_lock(&dcache_lock
);
849 node
= dentry
->d_subdirs
.next
;
851 spin_unlock(&dcache_lock
);
855 * NOTE : the dentry must have been dget()'ed
857 static void cgroup_d_remove_dir(struct dentry
*dentry
)
859 cgroup_clear_directory(dentry
);
861 spin_lock(&dcache_lock
);
862 list_del_init(&dentry
->d_u
.d_child
);
863 spin_unlock(&dcache_lock
);
868 * A queue for waiters to do rmdir() cgroup. A tasks will sleep when
869 * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some
870 * reference to css->refcnt. In general, this refcnt is expected to goes down
873 * CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex;
875 DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq
);
877 static void cgroup_wakeup_rmdir_waiter(struct cgroup
*cgrp
)
879 if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
)))
880 wake_up_all(&cgroup_rmdir_waitq
);
883 void cgroup_exclude_rmdir(struct cgroup_subsys_state
*css
)
888 void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state
*css
)
890 cgroup_wakeup_rmdir_waiter(css
->cgroup
);
895 * Call with cgroup_mutex held.
897 static int rebind_subsystems(struct cgroupfs_root
*root
,
898 unsigned long final_bits
)
900 unsigned long added_bits
, removed_bits
;
901 struct cgroup
*cgrp
= &root
->top_cgroup
;
904 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
906 removed_bits
= root
->actual_subsys_bits
& ~final_bits
;
907 added_bits
= final_bits
& ~root
->actual_subsys_bits
;
908 /* Check that any added subsystems are currently free */
909 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
910 unsigned long bit
= 1UL << i
;
911 struct cgroup_subsys
*ss
= subsys
[i
];
912 if (!(bit
& added_bits
))
915 * Nobody should tell us to do a subsys that doesn't exist:
916 * parse_cgroupfs_options should catch that case and refcounts
917 * ensure that subsystems won't disappear once selected.
920 if (ss
->root
!= &rootnode
) {
921 /* Subsystem isn't free */
926 /* Currently we don't handle adding/removing subsystems when
927 * any child cgroups exist. This is theoretically supportable
928 * but involves complex error handling, so it's being left until
930 if (root
->number_of_cgroups
> 1)
933 /* Process each subsystem */
934 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
935 struct cgroup_subsys
*ss
= subsys
[i
];
936 unsigned long bit
= 1UL << i
;
937 if (bit
& added_bits
) {
938 /* We're binding this subsystem to this hierarchy */
940 BUG_ON(cgrp
->subsys
[i
]);
941 BUG_ON(!dummytop
->subsys
[i
]);
942 BUG_ON(dummytop
->subsys
[i
]->cgroup
!= dummytop
);
943 mutex_lock(&ss
->hierarchy_mutex
);
944 cgrp
->subsys
[i
] = dummytop
->subsys
[i
];
945 cgrp
->subsys
[i
]->cgroup
= cgrp
;
946 list_move(&ss
->sibling
, &root
->subsys_list
);
950 mutex_unlock(&ss
->hierarchy_mutex
);
951 } else if (bit
& removed_bits
) {
952 /* We're removing this subsystem */
954 BUG_ON(cgrp
->subsys
[i
] != dummytop
->subsys
[i
]);
955 BUG_ON(cgrp
->subsys
[i
]->cgroup
!= cgrp
);
956 mutex_lock(&ss
->hierarchy_mutex
);
958 ss
->bind(ss
, dummytop
);
959 dummytop
->subsys
[i
]->cgroup
= dummytop
;
960 cgrp
->subsys
[i
] = NULL
;
961 subsys
[i
]->root
= &rootnode
;
962 list_move(&ss
->sibling
, &rootnode
.subsys_list
);
963 mutex_unlock(&ss
->hierarchy_mutex
);
964 } else if (bit
& final_bits
) {
965 /* Subsystem state should already exist */
967 BUG_ON(!cgrp
->subsys
[i
]);
969 /* Subsystem state shouldn't exist */
970 BUG_ON(cgrp
->subsys
[i
]);
973 root
->subsys_bits
= root
->actual_subsys_bits
= final_bits
;
979 static int cgroup_show_options(struct seq_file
*seq
, struct vfsmount
*vfs
)
981 struct cgroupfs_root
*root
= vfs
->mnt_sb
->s_fs_info
;
982 struct cgroup_subsys
*ss
;
984 mutex_lock(&cgroup_mutex
);
985 for_each_subsys(root
, ss
)
986 seq_printf(seq
, ",%s", ss
->name
);
987 if (test_bit(ROOT_NOPREFIX
, &root
->flags
))
988 seq_puts(seq
, ",noprefix");
989 if (strlen(root
->release_agent_path
))
990 seq_printf(seq
, ",release_agent=%s", root
->release_agent_path
);
991 if (strlen(root
->name
))
992 seq_printf(seq
, ",name=%s", root
->name
);
993 mutex_unlock(&cgroup_mutex
);
997 struct cgroup_sb_opts
{
998 unsigned long subsys_bits
;
1000 char *release_agent
;
1002 /* User explicitly requested empty subsystem */
1005 struct cgroupfs_root
*new_root
;
1010 * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call
1011 * with cgroup_mutex held to protect the subsys[] array.
1013 static int parse_cgroupfs_options(char *data
,
1014 struct cgroup_sb_opts
*opts
)
1016 char *token
, *o
= data
?: "all";
1017 unsigned long mask
= (unsigned long)-1;
1019 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
1021 #ifdef CONFIG_CPUSETS
1022 mask
= ~(1UL << cpuset_subsys_id
);
1025 memset(opts
, 0, sizeof(*opts
));
1027 while ((token
= strsep(&o
, ",")) != NULL
) {
1030 if (!strcmp(token
, "all")) {
1031 /* Add all non-disabled subsystems */
1033 opts
->subsys_bits
= 0;
1034 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1035 struct cgroup_subsys
*ss
= subsys
[i
];
1039 opts
->subsys_bits
|= 1ul << i
;
1041 } else if (!strcmp(token
, "none")) {
1042 /* Explicitly have no subsystems */
1044 } else if (!strcmp(token
, "noprefix")) {
1045 set_bit(ROOT_NOPREFIX
, &opts
->flags
);
1046 } else if (!strncmp(token
, "release_agent=", 14)) {
1047 /* Specifying two release agents is forbidden */
1048 if (opts
->release_agent
)
1050 opts
->release_agent
=
1051 kstrndup(token
+ 14, PATH_MAX
, GFP_KERNEL
);
1052 if (!opts
->release_agent
)
1054 } else if (!strncmp(token
, "name=", 5)) {
1056 const char *name
= token
+ 5;
1057 /* Can't specify an empty name */
1060 /* Must match [\w.-]+ */
1061 for (i
= 0; i
< strlen(name
); i
++) {
1065 if ((c
== '.') || (c
== '-') || (c
== '_'))
1069 /* Specifying two names is forbidden */
1072 opts
->name
= kstrndup(name
,
1073 MAX_CGROUP_ROOT_NAMELEN
,
1078 struct cgroup_subsys
*ss
;
1080 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1084 if (!strcmp(token
, ss
->name
)) {
1086 set_bit(i
, &opts
->subsys_bits
);
1090 if (i
== CGROUP_SUBSYS_COUNT
)
1095 /* Consistency checks */
1098 * Option noprefix was introduced just for backward compatibility
1099 * with the old cpuset, so we allow noprefix only if mounting just
1100 * the cpuset subsystem.
1102 if (test_bit(ROOT_NOPREFIX
, &opts
->flags
) &&
1103 (opts
->subsys_bits
& mask
))
1107 /* Can't specify "none" and some subsystems */
1108 if (opts
->subsys_bits
&& opts
->none
)
1112 * We either have to specify by name or by subsystems. (So all
1113 * empty hierarchies must have a name).
1115 if (!opts
->subsys_bits
&& !opts
->name
)
1121 static int cgroup_remount(struct super_block
*sb
, int *flags
, char *data
)
1124 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1125 struct cgroup
*cgrp
= &root
->top_cgroup
;
1126 struct cgroup_sb_opts opts
;
1129 mutex_lock(&cgrp
->dentry
->d_inode
->i_mutex
);
1130 mutex_lock(&cgroup_mutex
);
1132 /* See what subsystems are wanted */
1133 ret
= parse_cgroupfs_options(data
, &opts
);
1137 /* Don't allow flags to change at remount */
1138 if (opts
.flags
!= root
->flags
) {
1143 /* Don't allow name to change at remount */
1144 if (opts
.name
&& strcmp(opts
.name
, root
->name
)) {
1149 ret
= rebind_subsystems(root
, opts
.subsys_bits
);
1153 /* (re)populate subsystem files */
1154 cgroup_populate_dir(cgrp
);
1156 if (opts
.release_agent
)
1157 strcpy(root
->release_agent_path
, opts
.release_agent
);
1159 kfree(opts
.release_agent
);
1161 mutex_unlock(&cgroup_mutex
);
1162 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
1167 static const struct super_operations cgroup_ops
= {
1168 .statfs
= simple_statfs
,
1169 .drop_inode
= generic_delete_inode
,
1170 .show_options
= cgroup_show_options
,
1171 .remount_fs
= cgroup_remount
,
1174 static void init_cgroup_housekeeping(struct cgroup
*cgrp
)
1176 INIT_LIST_HEAD(&cgrp
->sibling
);
1177 INIT_LIST_HEAD(&cgrp
->children
);
1178 INIT_LIST_HEAD(&cgrp
->css_sets
);
1179 INIT_LIST_HEAD(&cgrp
->release_list
);
1180 INIT_LIST_HEAD(&cgrp
->pidlists
);
1181 mutex_init(&cgrp
->pidlist_mutex
);
1184 static void init_cgroup_root(struct cgroupfs_root
*root
)
1186 struct cgroup
*cgrp
= &root
->top_cgroup
;
1187 INIT_LIST_HEAD(&root
->subsys_list
);
1188 INIT_LIST_HEAD(&root
->root_list
);
1189 root
->number_of_cgroups
= 1;
1191 cgrp
->top_cgroup
= cgrp
;
1192 init_cgroup_housekeeping(cgrp
);
1195 static bool init_root_id(struct cgroupfs_root
*root
)
1200 if (!ida_pre_get(&hierarchy_ida
, GFP_KERNEL
))
1202 spin_lock(&hierarchy_id_lock
);
1203 /* Try to allocate the next unused ID */
1204 ret
= ida_get_new_above(&hierarchy_ida
, next_hierarchy_id
,
1205 &root
->hierarchy_id
);
1207 /* Try again starting from 0 */
1208 ret
= ida_get_new(&hierarchy_ida
, &root
->hierarchy_id
);
1210 next_hierarchy_id
= root
->hierarchy_id
+ 1;
1211 } else if (ret
!= -EAGAIN
) {
1212 /* Can only get here if the 31-bit IDR is full ... */
1215 spin_unlock(&hierarchy_id_lock
);
1220 static int cgroup_test_super(struct super_block
*sb
, void *data
)
1222 struct cgroup_sb_opts
*opts
= data
;
1223 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1225 /* If we asked for a name then it must match */
1226 if (opts
->name
&& strcmp(opts
->name
, root
->name
))
1230 * If we asked for subsystems (or explicitly for no
1231 * subsystems) then they must match
1233 if ((opts
->subsys_bits
|| opts
->none
)
1234 && (opts
->subsys_bits
!= root
->subsys_bits
))
1240 static struct cgroupfs_root
*cgroup_root_from_opts(struct cgroup_sb_opts
*opts
)
1242 struct cgroupfs_root
*root
;
1244 if (!opts
->subsys_bits
&& !opts
->none
)
1247 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
1249 return ERR_PTR(-ENOMEM
);
1251 if (!init_root_id(root
)) {
1253 return ERR_PTR(-ENOMEM
);
1255 init_cgroup_root(root
);
1257 root
->subsys_bits
= opts
->subsys_bits
;
1258 root
->flags
= opts
->flags
;
1259 if (opts
->release_agent
)
1260 strcpy(root
->release_agent_path
, opts
->release_agent
);
1262 strcpy(root
->name
, opts
->name
);
1266 static void cgroup_drop_root(struct cgroupfs_root
*root
)
1271 BUG_ON(!root
->hierarchy_id
);
1272 spin_lock(&hierarchy_id_lock
);
1273 ida_remove(&hierarchy_ida
, root
->hierarchy_id
);
1274 spin_unlock(&hierarchy_id_lock
);
1278 static int cgroup_set_super(struct super_block
*sb
, void *data
)
1281 struct cgroup_sb_opts
*opts
= data
;
1283 /* If we don't have a new root, we can't set up a new sb */
1284 if (!opts
->new_root
)
1287 BUG_ON(!opts
->subsys_bits
&& !opts
->none
);
1289 ret
= set_anon_super(sb
, NULL
);
1293 sb
->s_fs_info
= opts
->new_root
;
1294 opts
->new_root
->sb
= sb
;
1296 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
1297 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
1298 sb
->s_magic
= CGROUP_SUPER_MAGIC
;
1299 sb
->s_op
= &cgroup_ops
;
1304 static int cgroup_get_rootdir(struct super_block
*sb
)
1306 struct inode
*inode
=
1307 cgroup_new_inode(S_IFDIR
| S_IRUGO
| S_IXUGO
| S_IWUSR
, sb
);
1308 struct dentry
*dentry
;
1313 inode
->i_fop
= &simple_dir_operations
;
1314 inode
->i_op
= &cgroup_dir_inode_operations
;
1315 /* directories start off with i_nlink == 2 (for "." entry) */
1317 dentry
= d_alloc_root(inode
);
1322 sb
->s_root
= dentry
;
1326 static int cgroup_get_sb(struct file_system_type
*fs_type
,
1327 int flags
, const char *unused_dev_name
,
1328 void *data
, struct vfsmount
*mnt
)
1330 struct cgroup_sb_opts opts
;
1331 struct cgroupfs_root
*root
;
1333 struct super_block
*sb
;
1334 struct cgroupfs_root
*new_root
;
1336 /* First find the desired set of subsystems */
1337 mutex_lock(&cgroup_mutex
);
1338 ret
= parse_cgroupfs_options(data
, &opts
);
1339 mutex_unlock(&cgroup_mutex
);
1344 * Allocate a new cgroup root. We may not need it if we're
1345 * reusing an existing hierarchy.
1347 new_root
= cgroup_root_from_opts(&opts
);
1348 if (IS_ERR(new_root
)) {
1349 ret
= PTR_ERR(new_root
);
1352 opts
.new_root
= new_root
;
1354 /* Locate an existing or new sb for this hierarchy */
1355 sb
= sget(fs_type
, cgroup_test_super
, cgroup_set_super
, &opts
);
1358 cgroup_drop_root(opts
.new_root
);
1362 root
= sb
->s_fs_info
;
1364 if (root
== opts
.new_root
) {
1365 /* We used the new root structure, so this is a new hierarchy */
1366 struct list_head tmp_cg_links
;
1367 struct cgroup
*root_cgrp
= &root
->top_cgroup
;
1368 struct inode
*inode
;
1369 struct cgroupfs_root
*existing_root
;
1372 BUG_ON(sb
->s_root
!= NULL
);
1374 ret
= cgroup_get_rootdir(sb
);
1376 goto drop_new_super
;
1377 inode
= sb
->s_root
->d_inode
;
1379 mutex_lock(&inode
->i_mutex
);
1380 mutex_lock(&cgroup_mutex
);
1382 if (strlen(root
->name
)) {
1383 /* Check for name clashes with existing mounts */
1384 for_each_active_root(existing_root
) {
1385 if (!strcmp(existing_root
->name
, root
->name
)) {
1387 mutex_unlock(&cgroup_mutex
);
1388 mutex_unlock(&inode
->i_mutex
);
1389 goto drop_new_super
;
1395 * We're accessing css_set_count without locking
1396 * css_set_lock here, but that's OK - it can only be
1397 * increased by someone holding cgroup_lock, and
1398 * that's us. The worst that can happen is that we
1399 * have some link structures left over
1401 ret
= allocate_cg_links(css_set_count
, &tmp_cg_links
);
1403 mutex_unlock(&cgroup_mutex
);
1404 mutex_unlock(&inode
->i_mutex
);
1405 goto drop_new_super
;
1408 ret
= rebind_subsystems(root
, root
->subsys_bits
);
1409 if (ret
== -EBUSY
) {
1410 mutex_unlock(&cgroup_mutex
);
1411 mutex_unlock(&inode
->i_mutex
);
1412 free_cg_links(&tmp_cg_links
);
1413 goto drop_new_super
;
1416 /* EBUSY should be the only error here */
1419 list_add(&root
->root_list
, &roots
);
1422 sb
->s_root
->d_fsdata
= root_cgrp
;
1423 root
->top_cgroup
.dentry
= sb
->s_root
;
1425 /* Link the top cgroup in this hierarchy into all
1426 * the css_set objects */
1427 write_lock(&css_set_lock
);
1428 for (i
= 0; i
< CSS_SET_TABLE_SIZE
; i
++) {
1429 struct hlist_head
*hhead
= &css_set_table
[i
];
1430 struct hlist_node
*node
;
1433 hlist_for_each_entry(cg
, node
, hhead
, hlist
)
1434 link_css_set(&tmp_cg_links
, cg
, root_cgrp
);
1436 write_unlock(&css_set_lock
);
1438 free_cg_links(&tmp_cg_links
);
1440 BUG_ON(!list_empty(&root_cgrp
->sibling
));
1441 BUG_ON(!list_empty(&root_cgrp
->children
));
1442 BUG_ON(root
->number_of_cgroups
!= 1);
1444 cgroup_populate_dir(root_cgrp
);
1445 mutex_unlock(&cgroup_mutex
);
1446 mutex_unlock(&inode
->i_mutex
);
1449 * We re-used an existing hierarchy - the new root (if
1450 * any) is not needed
1452 cgroup_drop_root(opts
.new_root
);
1455 simple_set_mnt(mnt
, sb
);
1456 kfree(opts
.release_agent
);
1461 deactivate_locked_super(sb
);
1463 kfree(opts
.release_agent
);
1469 static void cgroup_kill_sb(struct super_block
*sb
) {
1470 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1471 struct cgroup
*cgrp
= &root
->top_cgroup
;
1473 struct cg_cgroup_link
*link
;
1474 struct cg_cgroup_link
*saved_link
;
1478 BUG_ON(root
->number_of_cgroups
!= 1);
1479 BUG_ON(!list_empty(&cgrp
->children
));
1480 BUG_ON(!list_empty(&cgrp
->sibling
));
1482 mutex_lock(&cgroup_mutex
);
1484 /* Rebind all subsystems back to the default hierarchy */
1485 ret
= rebind_subsystems(root
, 0);
1486 /* Shouldn't be able to fail ... */
1490 * Release all the links from css_sets to this hierarchy's
1493 write_lock(&css_set_lock
);
1495 list_for_each_entry_safe(link
, saved_link
, &cgrp
->css_sets
,
1497 list_del(&link
->cg_link_list
);
1498 list_del(&link
->cgrp_link_list
);
1501 write_unlock(&css_set_lock
);
1503 if (!list_empty(&root
->root_list
)) {
1504 list_del(&root
->root_list
);
1508 mutex_unlock(&cgroup_mutex
);
1510 kill_litter_super(sb
);
1511 cgroup_drop_root(root
);
1514 static struct file_system_type cgroup_fs_type
= {
1516 .get_sb
= cgroup_get_sb
,
1517 .kill_sb
= cgroup_kill_sb
,
1520 static inline struct cgroup
*__d_cgrp(struct dentry
*dentry
)
1522 return dentry
->d_fsdata
;
1525 static inline struct cftype
*__d_cft(struct dentry
*dentry
)
1527 return dentry
->d_fsdata
;
1531 * cgroup_path - generate the path of a cgroup
1532 * @cgrp: the cgroup in question
1533 * @buf: the buffer to write the path into
1534 * @buflen: the length of the buffer
1536 * Called with cgroup_mutex held or else with an RCU-protected cgroup
1537 * reference. Writes path of cgroup into buf. Returns 0 on success,
1540 int cgroup_path(const struct cgroup
*cgrp
, char *buf
, int buflen
)
1543 struct dentry
*dentry
= rcu_dereference(cgrp
->dentry
);
1545 if (!dentry
|| cgrp
== dummytop
) {
1547 * Inactive subsystems have no dentry for their root
1554 start
= buf
+ buflen
;
1558 int len
= dentry
->d_name
.len
;
1559 if ((start
-= len
) < buf
)
1560 return -ENAMETOOLONG
;
1561 memcpy(start
, cgrp
->dentry
->d_name
.name
, len
);
1562 cgrp
= cgrp
->parent
;
1565 dentry
= rcu_dereference(cgrp
->dentry
);
1569 return -ENAMETOOLONG
;
1572 memmove(buf
, start
, buf
+ buflen
- start
);
1577 * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp'
1578 * @cgrp: the cgroup the task is attaching to
1579 * @tsk: the task to be attached
1581 * Call holding cgroup_mutex. May take task_lock of
1582 * the task 'tsk' during call.
1584 int cgroup_attach_task(struct cgroup
*cgrp
, struct task_struct
*tsk
)
1587 struct cgroup_subsys
*ss
, *failed_ss
= NULL
;
1588 struct cgroup
*oldcgrp
;
1590 struct css_set
*newcg
;
1591 struct cgroupfs_root
*root
= cgrp
->root
;
1593 /* Nothing to do if the task is already in that cgroup */
1594 oldcgrp
= task_cgroup_from_root(tsk
, root
);
1595 if (cgrp
== oldcgrp
)
1598 for_each_subsys(root
, ss
) {
1599 if (ss
->can_attach
) {
1600 retval
= ss
->can_attach(ss
, cgrp
, tsk
, false);
1603 * Remember on which subsystem the can_attach()
1604 * failed, so that we only call cancel_attach()
1605 * against the subsystems whose can_attach()
1606 * succeeded. (See below)
1619 * Locate or allocate a new css_set for this task,
1620 * based on its final set of cgroups
1622 newcg
= find_css_set(cg
, cgrp
);
1630 if (tsk
->flags
& PF_EXITING
) {
1636 rcu_assign_pointer(tsk
->cgroups
, newcg
);
1639 /* Update the css_set linked lists if we're using them */
1640 write_lock(&css_set_lock
);
1641 if (!list_empty(&tsk
->cg_list
)) {
1642 list_del(&tsk
->cg_list
);
1643 list_add(&tsk
->cg_list
, &newcg
->tasks
);
1645 write_unlock(&css_set_lock
);
1647 for_each_subsys(root
, ss
) {
1649 ss
->attach(ss
, cgrp
, oldcgrp
, tsk
, false);
1651 set_bit(CGRP_RELEASABLE
, &oldcgrp
->flags
);
1656 * wake up rmdir() waiter. the rmdir should fail since the cgroup
1657 * is no longer empty.
1659 cgroup_wakeup_rmdir_waiter(cgrp
);
1662 for_each_subsys(root
, ss
) {
1663 if (ss
== failed_ss
)
1665 * This subsystem was the one that failed the
1666 * can_attach() check earlier, so we don't need
1667 * to call cancel_attach() against it or any
1668 * remaining subsystems.
1671 if (ss
->cancel_attach
)
1672 ss
->cancel_attach(ss
, cgrp
, tsk
, false);
1679 * Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex
1680 * held. May take task_lock of task
1682 static int attach_task_by_pid(struct cgroup
*cgrp
, u64 pid
)
1684 struct task_struct
*tsk
;
1685 const struct cred
*cred
= current_cred(), *tcred
;
1690 tsk
= find_task_by_vpid(pid
);
1691 if (!tsk
|| tsk
->flags
& PF_EXITING
) {
1696 tcred
= __task_cred(tsk
);
1698 cred
->euid
!= tcred
->uid
&&
1699 cred
->euid
!= tcred
->suid
) {
1703 get_task_struct(tsk
);
1707 get_task_struct(tsk
);
1710 ret
= cgroup_attach_task(cgrp
, tsk
);
1711 put_task_struct(tsk
);
1715 static int cgroup_tasks_write(struct cgroup
*cgrp
, struct cftype
*cft
, u64 pid
)
1718 if (!cgroup_lock_live_group(cgrp
))
1720 ret
= attach_task_by_pid(cgrp
, pid
);
1726 * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
1727 * @cgrp: the cgroup to be checked for liveness
1729 * On success, returns true; the lock should be later released with
1730 * cgroup_unlock(). On failure returns false with no lock held.
1732 bool cgroup_lock_live_group(struct cgroup
*cgrp
)
1734 mutex_lock(&cgroup_mutex
);
1735 if (cgroup_is_removed(cgrp
)) {
1736 mutex_unlock(&cgroup_mutex
);
1742 static int cgroup_release_agent_write(struct cgroup
*cgrp
, struct cftype
*cft
,
1745 BUILD_BUG_ON(sizeof(cgrp
->root
->release_agent_path
) < PATH_MAX
);
1746 if (!cgroup_lock_live_group(cgrp
))
1748 strcpy(cgrp
->root
->release_agent_path
, buffer
);
1753 static int cgroup_release_agent_show(struct cgroup
*cgrp
, struct cftype
*cft
,
1754 struct seq_file
*seq
)
1756 if (!cgroup_lock_live_group(cgrp
))
1758 seq_puts(seq
, cgrp
->root
->release_agent_path
);
1759 seq_putc(seq
, '\n');
1764 /* A buffer size big enough for numbers or short strings */
1765 #define CGROUP_LOCAL_BUFFER_SIZE 64
1767 static ssize_t
cgroup_write_X64(struct cgroup
*cgrp
, struct cftype
*cft
,
1769 const char __user
*userbuf
,
1770 size_t nbytes
, loff_t
*unused_ppos
)
1772 char buffer
[CGROUP_LOCAL_BUFFER_SIZE
];
1778 if (nbytes
>= sizeof(buffer
))
1780 if (copy_from_user(buffer
, userbuf
, nbytes
))
1783 buffer
[nbytes
] = 0; /* nul-terminate */
1784 if (cft
->write_u64
) {
1785 u64 val
= simple_strtoull(strstrip(buffer
), &end
, 0);
1788 retval
= cft
->write_u64(cgrp
, cft
, val
);
1790 s64 val
= simple_strtoll(strstrip(buffer
), &end
, 0);
1793 retval
= cft
->write_s64(cgrp
, cft
, val
);
1800 static ssize_t
cgroup_write_string(struct cgroup
*cgrp
, struct cftype
*cft
,
1802 const char __user
*userbuf
,
1803 size_t nbytes
, loff_t
*unused_ppos
)
1805 char local_buffer
[CGROUP_LOCAL_BUFFER_SIZE
];
1807 size_t max_bytes
= cft
->max_write_len
;
1808 char *buffer
= local_buffer
;
1811 max_bytes
= sizeof(local_buffer
) - 1;
1812 if (nbytes
>= max_bytes
)
1814 /* Allocate a dynamic buffer if we need one */
1815 if (nbytes
>= sizeof(local_buffer
)) {
1816 buffer
= kmalloc(nbytes
+ 1, GFP_KERNEL
);
1820 if (nbytes
&& copy_from_user(buffer
, userbuf
, nbytes
)) {
1825 buffer
[nbytes
] = 0; /* nul-terminate */
1826 retval
= cft
->write_string(cgrp
, cft
, strstrip(buffer
));
1830 if (buffer
!= local_buffer
)
1835 static ssize_t
cgroup_file_write(struct file
*file
, const char __user
*buf
,
1836 size_t nbytes
, loff_t
*ppos
)
1838 struct cftype
*cft
= __d_cft(file
->f_dentry
);
1839 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
1841 if (cgroup_is_removed(cgrp
))
1844 return cft
->write(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1845 if (cft
->write_u64
|| cft
->write_s64
)
1846 return cgroup_write_X64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1847 if (cft
->write_string
)
1848 return cgroup_write_string(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1850 int ret
= cft
->trigger(cgrp
, (unsigned int)cft
->private);
1851 return ret
? ret
: nbytes
;
1856 static ssize_t
cgroup_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
,
1858 char __user
*buf
, size_t nbytes
,
1861 char tmp
[CGROUP_LOCAL_BUFFER_SIZE
];
1862 u64 val
= cft
->read_u64(cgrp
, cft
);
1863 int len
= sprintf(tmp
, "%llu\n", (unsigned long long) val
);
1865 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
1868 static ssize_t
cgroup_read_s64(struct cgroup
*cgrp
, struct cftype
*cft
,
1870 char __user
*buf
, size_t nbytes
,
1873 char tmp
[CGROUP_LOCAL_BUFFER_SIZE
];
1874 s64 val
= cft
->read_s64(cgrp
, cft
);
1875 int len
= sprintf(tmp
, "%lld\n", (long long) val
);
1877 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
1880 static ssize_t
cgroup_file_read(struct file
*file
, char __user
*buf
,
1881 size_t nbytes
, loff_t
*ppos
)
1883 struct cftype
*cft
= __d_cft(file
->f_dentry
);
1884 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
1886 if (cgroup_is_removed(cgrp
))
1890 return cft
->read(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1892 return cgroup_read_u64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1894 return cgroup_read_s64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1899 * seqfile ops/methods for returning structured data. Currently just
1900 * supports string->u64 maps, but can be extended in future.
1903 struct cgroup_seqfile_state
{
1905 struct cgroup
*cgroup
;
1908 static int cgroup_map_add(struct cgroup_map_cb
*cb
, const char *key
, u64 value
)
1910 struct seq_file
*sf
= cb
->state
;
1911 return seq_printf(sf
, "%s %llu\n", key
, (unsigned long long)value
);
1914 static int cgroup_seqfile_show(struct seq_file
*m
, void *arg
)
1916 struct cgroup_seqfile_state
*state
= m
->private;
1917 struct cftype
*cft
= state
->cft
;
1918 if (cft
->read_map
) {
1919 struct cgroup_map_cb cb
= {
1920 .fill
= cgroup_map_add
,
1923 return cft
->read_map(state
->cgroup
, cft
, &cb
);
1925 return cft
->read_seq_string(state
->cgroup
, cft
, m
);
1928 static int cgroup_seqfile_release(struct inode
*inode
, struct file
*file
)
1930 struct seq_file
*seq
= file
->private_data
;
1931 kfree(seq
->private);
1932 return single_release(inode
, file
);
1935 static const struct file_operations cgroup_seqfile_operations
= {
1937 .write
= cgroup_file_write
,
1938 .llseek
= seq_lseek
,
1939 .release
= cgroup_seqfile_release
,
1942 static int cgroup_file_open(struct inode
*inode
, struct file
*file
)
1947 err
= generic_file_open(inode
, file
);
1950 cft
= __d_cft(file
->f_dentry
);
1952 if (cft
->read_map
|| cft
->read_seq_string
) {
1953 struct cgroup_seqfile_state
*state
=
1954 kzalloc(sizeof(*state
), GFP_USER
);
1958 state
->cgroup
= __d_cgrp(file
->f_dentry
->d_parent
);
1959 file
->f_op
= &cgroup_seqfile_operations
;
1960 err
= single_open(file
, cgroup_seqfile_show
, state
);
1963 } else if (cft
->open
)
1964 err
= cft
->open(inode
, file
);
1971 static int cgroup_file_release(struct inode
*inode
, struct file
*file
)
1973 struct cftype
*cft
= __d_cft(file
->f_dentry
);
1975 return cft
->release(inode
, file
);
1980 * cgroup_rename - Only allow simple rename of directories in place.
1982 static int cgroup_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
1983 struct inode
*new_dir
, struct dentry
*new_dentry
)
1985 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
))
1987 if (new_dentry
->d_inode
)
1989 if (old_dir
!= new_dir
)
1991 return simple_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
1994 static const struct file_operations cgroup_file_operations
= {
1995 .read
= cgroup_file_read
,
1996 .write
= cgroup_file_write
,
1997 .llseek
= generic_file_llseek
,
1998 .open
= cgroup_file_open
,
1999 .release
= cgroup_file_release
,
2002 static const struct inode_operations cgroup_dir_inode_operations
= {
2003 .lookup
= simple_lookup
,
2004 .mkdir
= cgroup_mkdir
,
2005 .rmdir
= cgroup_rmdir
,
2006 .rename
= cgroup_rename
,
2009 static int cgroup_create_file(struct dentry
*dentry
, mode_t mode
,
2010 struct super_block
*sb
)
2012 static const struct dentry_operations cgroup_dops
= {
2013 .d_iput
= cgroup_diput
,
2016 struct inode
*inode
;
2020 if (dentry
->d_inode
)
2023 inode
= cgroup_new_inode(mode
, sb
);
2027 if (S_ISDIR(mode
)) {
2028 inode
->i_op
= &cgroup_dir_inode_operations
;
2029 inode
->i_fop
= &simple_dir_operations
;
2031 /* start off with i_nlink == 2 (for "." entry) */
2034 /* start with the directory inode held, so that we can
2035 * populate it without racing with another mkdir */
2036 mutex_lock_nested(&inode
->i_mutex
, I_MUTEX_CHILD
);
2037 } else if (S_ISREG(mode
)) {
2039 inode
->i_fop
= &cgroup_file_operations
;
2041 dentry
->d_op
= &cgroup_dops
;
2042 d_instantiate(dentry
, inode
);
2043 dget(dentry
); /* Extra count - pin the dentry in core */
2048 * cgroup_create_dir - create a directory for an object.
2049 * @cgrp: the cgroup we create the directory for. It must have a valid
2050 * ->parent field. And we are going to fill its ->dentry field.
2051 * @dentry: dentry of the new cgroup
2052 * @mode: mode to set on new directory.
2054 static int cgroup_create_dir(struct cgroup
*cgrp
, struct dentry
*dentry
,
2057 struct dentry
*parent
;
2060 parent
= cgrp
->parent
->dentry
;
2061 error
= cgroup_create_file(dentry
, S_IFDIR
| mode
, cgrp
->root
->sb
);
2063 dentry
->d_fsdata
= cgrp
;
2064 inc_nlink(parent
->d_inode
);
2065 rcu_assign_pointer(cgrp
->dentry
, dentry
);
2074 * cgroup_file_mode - deduce file mode of a control file
2075 * @cft: the control file in question
2077 * returns cft->mode if ->mode is not 0
2078 * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
2079 * returns S_IRUGO if it has only a read handler
2080 * returns S_IWUSR if it has only a write hander
2082 static mode_t
cgroup_file_mode(const struct cftype
*cft
)
2089 if (cft
->read
|| cft
->read_u64
|| cft
->read_s64
||
2090 cft
->read_map
|| cft
->read_seq_string
)
2093 if (cft
->write
|| cft
->write_u64
|| cft
->write_s64
||
2094 cft
->write_string
|| cft
->trigger
)
2100 int cgroup_add_file(struct cgroup
*cgrp
,
2101 struct cgroup_subsys
*subsys
,
2102 const struct cftype
*cft
)
2104 struct dentry
*dir
= cgrp
->dentry
;
2105 struct dentry
*dentry
;
2109 char name
[MAX_CGROUP_TYPE_NAMELEN
+ MAX_CFTYPE_NAME
+ 2] = { 0 };
2110 if (subsys
&& !test_bit(ROOT_NOPREFIX
, &cgrp
->root
->flags
)) {
2111 strcpy(name
, subsys
->name
);
2114 strcat(name
, cft
->name
);
2115 BUG_ON(!mutex_is_locked(&dir
->d_inode
->i_mutex
));
2116 dentry
= lookup_one_len(name
, dir
, strlen(name
));
2117 if (!IS_ERR(dentry
)) {
2118 mode
= cgroup_file_mode(cft
);
2119 error
= cgroup_create_file(dentry
, mode
| S_IFREG
,
2122 dentry
->d_fsdata
= (void *)cft
;
2125 error
= PTR_ERR(dentry
);
2129 int cgroup_add_files(struct cgroup
*cgrp
,
2130 struct cgroup_subsys
*subsys
,
2131 const struct cftype cft
[],
2135 for (i
= 0; i
< count
; i
++) {
2136 err
= cgroup_add_file(cgrp
, subsys
, &cft
[i
]);
2144 * cgroup_task_count - count the number of tasks in a cgroup.
2145 * @cgrp: the cgroup in question
2147 * Return the number of tasks in the cgroup.
2149 int cgroup_task_count(const struct cgroup
*cgrp
)
2152 struct cg_cgroup_link
*link
;
2154 read_lock(&css_set_lock
);
2155 list_for_each_entry(link
, &cgrp
->css_sets
, cgrp_link_list
) {
2156 count
+= atomic_read(&link
->cg
->refcount
);
2158 read_unlock(&css_set_lock
);
2163 * Advance a list_head iterator. The iterator should be positioned at
2164 * the start of a css_set
2166 static void cgroup_advance_iter(struct cgroup
*cgrp
,
2167 struct cgroup_iter
*it
)
2169 struct list_head
*l
= it
->cg_link
;
2170 struct cg_cgroup_link
*link
;
2173 /* Advance to the next non-empty css_set */
2176 if (l
== &cgrp
->css_sets
) {
2180 link
= list_entry(l
, struct cg_cgroup_link
, cgrp_link_list
);
2182 } while (list_empty(&cg
->tasks
));
2184 it
->task
= cg
->tasks
.next
;
2188 * To reduce the fork() overhead for systems that are not actually
2189 * using their cgroups capability, we don't maintain the lists running
2190 * through each css_set to its tasks until we see the list actually
2191 * used - in other words after the first call to cgroup_iter_start().
2193 * The tasklist_lock is not held here, as do_each_thread() and
2194 * while_each_thread() are protected by RCU.
2196 static void cgroup_enable_task_cg_lists(void)
2198 struct task_struct
*p
, *g
;
2199 write_lock(&css_set_lock
);
2200 use_task_css_set_links
= 1;
2201 do_each_thread(g
, p
) {
2204 * We should check if the process is exiting, otherwise
2205 * it will race with cgroup_exit() in that the list
2206 * entry won't be deleted though the process has exited.
2208 if (!(p
->flags
& PF_EXITING
) && list_empty(&p
->cg_list
))
2209 list_add(&p
->cg_list
, &p
->cgroups
->tasks
);
2211 } while_each_thread(g
, p
);
2212 write_unlock(&css_set_lock
);
2215 void cgroup_iter_start(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
2218 * The first time anyone tries to iterate across a cgroup,
2219 * we need to enable the list linking each css_set to its
2220 * tasks, and fix up all existing tasks.
2222 if (!use_task_css_set_links
)
2223 cgroup_enable_task_cg_lists();
2225 read_lock(&css_set_lock
);
2226 it
->cg_link
= &cgrp
->css_sets
;
2227 cgroup_advance_iter(cgrp
, it
);
2230 struct task_struct
*cgroup_iter_next(struct cgroup
*cgrp
,
2231 struct cgroup_iter
*it
)
2233 struct task_struct
*res
;
2234 struct list_head
*l
= it
->task
;
2235 struct cg_cgroup_link
*link
;
2237 /* If the iterator cg is NULL, we have no tasks */
2240 res
= list_entry(l
, struct task_struct
, cg_list
);
2241 /* Advance iterator to find next entry */
2243 link
= list_entry(it
->cg_link
, struct cg_cgroup_link
, cgrp_link_list
);
2244 if (l
== &link
->cg
->tasks
) {
2245 /* We reached the end of this task list - move on to
2246 * the next cg_cgroup_link */
2247 cgroup_advance_iter(cgrp
, it
);
2254 void cgroup_iter_end(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
2256 read_unlock(&css_set_lock
);
2259 static inline int started_after_time(struct task_struct
*t1
,
2260 struct timespec
*time
,
2261 struct task_struct
*t2
)
2263 int start_diff
= timespec_compare(&t1
->start_time
, time
);
2264 if (start_diff
> 0) {
2266 } else if (start_diff
< 0) {
2270 * Arbitrarily, if two processes started at the same
2271 * time, we'll say that the lower pointer value
2272 * started first. Note that t2 may have exited by now
2273 * so this may not be a valid pointer any longer, but
2274 * that's fine - it still serves to distinguish
2275 * between two tasks started (effectively) simultaneously.
2282 * This function is a callback from heap_insert() and is used to order
2284 * In this case we order the heap in descending task start time.
2286 static inline int started_after(void *p1
, void *p2
)
2288 struct task_struct
*t1
= p1
;
2289 struct task_struct
*t2
= p2
;
2290 return started_after_time(t1
, &t2
->start_time
, t2
);
2294 * cgroup_scan_tasks - iterate though all the tasks in a cgroup
2295 * @scan: struct cgroup_scanner containing arguments for the scan
2297 * Arguments include pointers to callback functions test_task() and
2299 * Iterate through all the tasks in a cgroup, calling test_task() for each,
2300 * and if it returns true, call process_task() for it also.
2301 * The test_task pointer may be NULL, meaning always true (select all tasks).
2302 * Effectively duplicates cgroup_iter_{start,next,end}()
2303 * but does not lock css_set_lock for the call to process_task().
2304 * The struct cgroup_scanner may be embedded in any structure of the caller's
2306 * It is guaranteed that process_task() will act on every task that
2307 * is a member of the cgroup for the duration of this call. This
2308 * function may or may not call process_task() for tasks that exit
2309 * or move to a different cgroup during the call, or are forked or
2310 * move into the cgroup during the call.
2312 * Note that test_task() may be called with locks held, and may in some
2313 * situations be called multiple times for the same task, so it should
2315 * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been
2316 * pre-allocated and will be used for heap operations (and its "gt" member will
2317 * be overwritten), else a temporary heap will be used (allocation of which
2318 * may cause this function to fail).
2320 int cgroup_scan_tasks(struct cgroup_scanner
*scan
)
2323 struct cgroup_iter it
;
2324 struct task_struct
*p
, *dropped
;
2325 /* Never dereference latest_task, since it's not refcounted */
2326 struct task_struct
*latest_task
= NULL
;
2327 struct ptr_heap tmp_heap
;
2328 struct ptr_heap
*heap
;
2329 struct timespec latest_time
= { 0, 0 };
2332 /* The caller supplied our heap and pre-allocated its memory */
2334 heap
->gt
= &started_after
;
2336 /* We need to allocate our own heap memory */
2338 retval
= heap_init(heap
, PAGE_SIZE
, GFP_KERNEL
, &started_after
);
2340 /* cannot allocate the heap */
2346 * Scan tasks in the cgroup, using the scanner's "test_task" callback
2347 * to determine which are of interest, and using the scanner's
2348 * "process_task" callback to process any of them that need an update.
2349 * Since we don't want to hold any locks during the task updates,
2350 * gather tasks to be processed in a heap structure.
2351 * The heap is sorted by descending task start time.
2352 * If the statically-sized heap fills up, we overflow tasks that
2353 * started later, and in future iterations only consider tasks that
2354 * started after the latest task in the previous pass. This
2355 * guarantees forward progress and that we don't miss any tasks.
2358 cgroup_iter_start(scan
->cg
, &it
);
2359 while ((p
= cgroup_iter_next(scan
->cg
, &it
))) {
2361 * Only affect tasks that qualify per the caller's callback,
2362 * if he provided one
2364 if (scan
->test_task
&& !scan
->test_task(p
, scan
))
2367 * Only process tasks that started after the last task
2370 if (!started_after_time(p
, &latest_time
, latest_task
))
2372 dropped
= heap_insert(heap
, p
);
2373 if (dropped
== NULL
) {
2375 * The new task was inserted; the heap wasn't
2379 } else if (dropped
!= p
) {
2381 * The new task was inserted, and pushed out a
2385 put_task_struct(dropped
);
2388 * Else the new task was newer than anything already in
2389 * the heap and wasn't inserted
2392 cgroup_iter_end(scan
->cg
, &it
);
2395 for (i
= 0; i
< heap
->size
; i
++) {
2396 struct task_struct
*q
= heap
->ptrs
[i
];
2398 latest_time
= q
->start_time
;
2401 /* Process the task per the caller's callback */
2402 scan
->process_task(q
, scan
);
2406 * If we had to process any tasks at all, scan again
2407 * in case some of them were in the middle of forking
2408 * children that didn't get processed.
2409 * Not the most efficient way to do it, but it avoids
2410 * having to take callback_mutex in the fork path
2414 if (heap
== &tmp_heap
)
2415 heap_free(&tmp_heap
);
2420 * Stuff for reading the 'tasks'/'procs' files.
2422 * Reading this file can return large amounts of data if a cgroup has
2423 * *lots* of attached tasks. So it may need several calls to read(),
2424 * but we cannot guarantee that the information we produce is correct
2425 * unless we produce it entirely atomically.
2430 * The following two functions "fix" the issue where there are more pids
2431 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
2432 * TODO: replace with a kernel-wide solution to this problem
2434 #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
2435 static void *pidlist_allocate(int count
)
2437 if (PIDLIST_TOO_LARGE(count
))
2438 return vmalloc(count
* sizeof(pid_t
));
2440 return kmalloc(count
* sizeof(pid_t
), GFP_KERNEL
);
2442 static void pidlist_free(void *p
)
2444 if (is_vmalloc_addr(p
))
2449 static void *pidlist_resize(void *p
, int newcount
)
2452 /* note: if new alloc fails, old p will still be valid either way */
2453 if (is_vmalloc_addr(p
)) {
2454 newlist
= vmalloc(newcount
* sizeof(pid_t
));
2457 memcpy(newlist
, p
, newcount
* sizeof(pid_t
));
2460 newlist
= krealloc(p
, newcount
* sizeof(pid_t
), GFP_KERNEL
);
2466 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
2467 * If the new stripped list is sufficiently smaller and there's enough memory
2468 * to allocate a new buffer, will let go of the unneeded memory. Returns the
2469 * number of unique elements.
2471 /* is the size difference enough that we should re-allocate the array? */
2472 #define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new))
2473 static int pidlist_uniq(pid_t
**p
, int length
)
2480 * we presume the 0th element is unique, so i starts at 1. trivial
2481 * edge cases first; no work needs to be done for either
2483 if (length
== 0 || length
== 1)
2485 /* src and dest walk down the list; dest counts unique elements */
2486 for (src
= 1; src
< length
; src
++) {
2487 /* find next unique element */
2488 while (list
[src
] == list
[src
-1]) {
2493 /* dest always points to where the next unique element goes */
2494 list
[dest
] = list
[src
];
2499 * if the length difference is large enough, we want to allocate a
2500 * smaller buffer to save memory. if this fails due to out of memory,
2501 * we'll just stay with what we've got.
2503 if (PIDLIST_REALLOC_DIFFERENCE(length
, dest
)) {
2504 newlist
= pidlist_resize(list
, dest
);
2511 static int cmppid(const void *a
, const void *b
)
2513 return *(pid_t
*)a
- *(pid_t
*)b
;
2517 * find the appropriate pidlist for our purpose (given procs vs tasks)
2518 * returns with the lock on that pidlist already held, and takes care
2519 * of the use count, or returns NULL with no locks held if we're out of
2522 static struct cgroup_pidlist
*cgroup_pidlist_find(struct cgroup
*cgrp
,
2523 enum cgroup_filetype type
)
2525 struct cgroup_pidlist
*l
;
2526 /* don't need task_nsproxy() if we're looking at ourself */
2527 struct pid_namespace
*ns
= get_pid_ns(current
->nsproxy
->pid_ns
);
2529 * We can't drop the pidlist_mutex before taking the l->mutex in case
2530 * the last ref-holder is trying to remove l from the list at the same
2531 * time. Holding the pidlist_mutex precludes somebody taking whichever
2532 * list we find out from under us - compare release_pid_array().
2534 mutex_lock(&cgrp
->pidlist_mutex
);
2535 list_for_each_entry(l
, &cgrp
->pidlists
, links
) {
2536 if (l
->key
.type
== type
&& l
->key
.ns
== ns
) {
2537 /* found a matching list - drop the extra refcount */
2539 /* make sure l doesn't vanish out from under us */
2540 down_write(&l
->mutex
);
2541 mutex_unlock(&cgrp
->pidlist_mutex
);
2545 /* entry not found; create a new one */
2546 l
= kmalloc(sizeof(struct cgroup_pidlist
), GFP_KERNEL
);
2548 mutex_unlock(&cgrp
->pidlist_mutex
);
2552 init_rwsem(&l
->mutex
);
2553 down_write(&l
->mutex
);
2556 l
->use_count
= 0; /* don't increment here */
2559 list_add(&l
->links
, &cgrp
->pidlists
);
2560 mutex_unlock(&cgrp
->pidlist_mutex
);
2565 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
2567 static int pidlist_array_load(struct cgroup
*cgrp
, enum cgroup_filetype type
,
2568 struct cgroup_pidlist
**lp
)
2572 int pid
, n
= 0; /* used for populating the array */
2573 struct cgroup_iter it
;
2574 struct task_struct
*tsk
;
2575 struct cgroup_pidlist
*l
;
2578 * If cgroup gets more users after we read count, we won't have
2579 * enough space - tough. This race is indistinguishable to the
2580 * caller from the case that the additional cgroup users didn't
2581 * show up until sometime later on.
2583 length
= cgroup_task_count(cgrp
);
2584 array
= pidlist_allocate(length
);
2587 /* now, populate the array */
2588 cgroup_iter_start(cgrp
, &it
);
2589 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
2590 if (unlikely(n
== length
))
2592 /* get tgid or pid for procs or tasks file respectively */
2593 if (type
== CGROUP_FILE_PROCS
)
2594 pid
= task_tgid_vnr(tsk
);
2596 pid
= task_pid_vnr(tsk
);
2597 if (pid
> 0) /* make sure to only use valid results */
2600 cgroup_iter_end(cgrp
, &it
);
2602 /* now sort & (if procs) strip out duplicates */
2603 sort(array
, length
, sizeof(pid_t
), cmppid
, NULL
);
2604 if (type
== CGROUP_FILE_PROCS
)
2605 length
= pidlist_uniq(&array
, length
);
2606 l
= cgroup_pidlist_find(cgrp
, type
);
2608 pidlist_free(array
);
2611 /* store array, freeing old if necessary - lock already held */
2612 pidlist_free(l
->list
);
2616 up_write(&l
->mutex
);
2622 * cgroupstats_build - build and fill cgroupstats
2623 * @stats: cgroupstats to fill information into
2624 * @dentry: A dentry entry belonging to the cgroup for which stats have
2627 * Build and fill cgroupstats so that taskstats can export it to user
2630 int cgroupstats_build(struct cgroupstats
*stats
, struct dentry
*dentry
)
2633 struct cgroup
*cgrp
;
2634 struct cgroup_iter it
;
2635 struct task_struct
*tsk
;
2638 * Validate dentry by checking the superblock operations,
2639 * and make sure it's a directory.
2641 if (dentry
->d_sb
->s_op
!= &cgroup_ops
||
2642 !S_ISDIR(dentry
->d_inode
->i_mode
))
2646 cgrp
= dentry
->d_fsdata
;
2648 cgroup_iter_start(cgrp
, &it
);
2649 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
2650 switch (tsk
->state
) {
2652 stats
->nr_running
++;
2654 case TASK_INTERRUPTIBLE
:
2655 stats
->nr_sleeping
++;
2657 case TASK_UNINTERRUPTIBLE
:
2658 stats
->nr_uninterruptible
++;
2661 stats
->nr_stopped
++;
2664 if (delayacct_is_task_waiting_on_io(tsk
))
2665 stats
->nr_io_wait
++;
2669 cgroup_iter_end(cgrp
, &it
);
2677 * seq_file methods for the tasks/procs files. The seq_file position is the
2678 * next pid to display; the seq_file iterator is a pointer to the pid
2679 * in the cgroup->l->list array.
2682 static void *cgroup_pidlist_start(struct seq_file
*s
, loff_t
*pos
)
2685 * Initially we receive a position value that corresponds to
2686 * one more than the last pid shown (or 0 on the first call or
2687 * after a seek to the start). Use a binary-search to find the
2688 * next pid to display, if any
2690 struct cgroup_pidlist
*l
= s
->private;
2691 int index
= 0, pid
= *pos
;
2694 down_read(&l
->mutex
);
2696 int end
= l
->length
;
2698 while (index
< end
) {
2699 int mid
= (index
+ end
) / 2;
2700 if (l
->list
[mid
] == pid
) {
2703 } else if (l
->list
[mid
] <= pid
)
2709 /* If we're off the end of the array, we're done */
2710 if (index
>= l
->length
)
2712 /* Update the abstract position to be the actual pid that we found */
2713 iter
= l
->list
+ index
;
2718 static void cgroup_pidlist_stop(struct seq_file
*s
, void *v
)
2720 struct cgroup_pidlist
*l
= s
->private;
2724 static void *cgroup_pidlist_next(struct seq_file
*s
, void *v
, loff_t
*pos
)
2726 struct cgroup_pidlist
*l
= s
->private;
2728 pid_t
*end
= l
->list
+ l
->length
;
2730 * Advance to the next pid in the array. If this goes off the
2742 static int cgroup_pidlist_show(struct seq_file
*s
, void *v
)
2744 return seq_printf(s
, "%d\n", *(int *)v
);
2748 * seq_operations functions for iterating on pidlists through seq_file -
2749 * independent of whether it's tasks or procs
2751 static const struct seq_operations cgroup_pidlist_seq_operations
= {
2752 .start
= cgroup_pidlist_start
,
2753 .stop
= cgroup_pidlist_stop
,
2754 .next
= cgroup_pidlist_next
,
2755 .show
= cgroup_pidlist_show
,
2758 static void cgroup_release_pid_array(struct cgroup_pidlist
*l
)
2761 * the case where we're the last user of this particular pidlist will
2762 * have us remove it from the cgroup's list, which entails taking the
2763 * mutex. since in pidlist_find the pidlist->lock depends on cgroup->
2764 * pidlist_mutex, we have to take pidlist_mutex first.
2766 mutex_lock(&l
->owner
->pidlist_mutex
);
2767 down_write(&l
->mutex
);
2768 BUG_ON(!l
->use_count
);
2769 if (!--l
->use_count
) {
2770 /* we're the last user if refcount is 0; remove and free */
2771 list_del(&l
->links
);
2772 mutex_unlock(&l
->owner
->pidlist_mutex
);
2773 pidlist_free(l
->list
);
2774 put_pid_ns(l
->key
.ns
);
2775 up_write(&l
->mutex
);
2779 mutex_unlock(&l
->owner
->pidlist_mutex
);
2780 up_write(&l
->mutex
);
2783 static int cgroup_pidlist_release(struct inode
*inode
, struct file
*file
)
2785 struct cgroup_pidlist
*l
;
2786 if (!(file
->f_mode
& FMODE_READ
))
2789 * the seq_file will only be initialized if the file was opened for
2790 * reading; hence we check if it's not null only in that case.
2792 l
= ((struct seq_file
*)file
->private_data
)->private;
2793 cgroup_release_pid_array(l
);
2794 return seq_release(inode
, file
);
2797 static const struct file_operations cgroup_pidlist_operations
= {
2799 .llseek
= seq_lseek
,
2800 .write
= cgroup_file_write
,
2801 .release
= cgroup_pidlist_release
,
2805 * The following functions handle opens on a file that displays a pidlist
2806 * (tasks or procs). Prepare an array of the process/thread IDs of whoever's
2809 /* helper function for the two below it */
2810 static int cgroup_pidlist_open(struct file
*file
, enum cgroup_filetype type
)
2812 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
2813 struct cgroup_pidlist
*l
;
2816 /* Nothing to do for write-only files */
2817 if (!(file
->f_mode
& FMODE_READ
))
2820 /* have the array populated */
2821 retval
= pidlist_array_load(cgrp
, type
, &l
);
2824 /* configure file information */
2825 file
->f_op
= &cgroup_pidlist_operations
;
2827 retval
= seq_open(file
, &cgroup_pidlist_seq_operations
);
2829 cgroup_release_pid_array(l
);
2832 ((struct seq_file
*)file
->private_data
)->private = l
;
2835 static int cgroup_tasks_open(struct inode
*unused
, struct file
*file
)
2837 return cgroup_pidlist_open(file
, CGROUP_FILE_TASKS
);
2839 static int cgroup_procs_open(struct inode
*unused
, struct file
*file
)
2841 return cgroup_pidlist_open(file
, CGROUP_FILE_PROCS
);
2844 static u64
cgroup_read_notify_on_release(struct cgroup
*cgrp
,
2847 return notify_on_release(cgrp
);
2850 static int cgroup_write_notify_on_release(struct cgroup
*cgrp
,
2854 clear_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
2856 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
2858 clear_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
2863 * for the common functions, 'private' gives the type of file
2865 /* for hysterical raisins, we can't put this on the older files */
2866 #define CGROUP_FILE_GENERIC_PREFIX "cgroup."
2867 static struct cftype files
[] = {
2870 .open
= cgroup_tasks_open
,
2871 .write_u64
= cgroup_tasks_write
,
2872 .release
= cgroup_pidlist_release
,
2873 .mode
= S_IRUGO
| S_IWUSR
,
2876 .name
= CGROUP_FILE_GENERIC_PREFIX
"procs",
2877 .open
= cgroup_procs_open
,
2878 /* .write_u64 = cgroup_procs_write, TODO */
2879 .release
= cgroup_pidlist_release
,
2883 .name
= "notify_on_release",
2884 .read_u64
= cgroup_read_notify_on_release
,
2885 .write_u64
= cgroup_write_notify_on_release
,
2889 static struct cftype cft_release_agent
= {
2890 .name
= "release_agent",
2891 .read_seq_string
= cgroup_release_agent_show
,
2892 .write_string
= cgroup_release_agent_write
,
2893 .max_write_len
= PATH_MAX
,
2896 static int cgroup_populate_dir(struct cgroup
*cgrp
)
2899 struct cgroup_subsys
*ss
;
2901 /* First clear out any existing files */
2902 cgroup_clear_directory(cgrp
->dentry
);
2904 err
= cgroup_add_files(cgrp
, NULL
, files
, ARRAY_SIZE(files
));
2908 if (cgrp
== cgrp
->top_cgroup
) {
2909 if ((err
= cgroup_add_file(cgrp
, NULL
, &cft_release_agent
)) < 0)
2913 for_each_subsys(cgrp
->root
, ss
) {
2914 if (ss
->populate
&& (err
= ss
->populate(ss
, cgrp
)) < 0)
2917 /* This cgroup is ready now */
2918 for_each_subsys(cgrp
->root
, ss
) {
2919 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
2921 * Update id->css pointer and make this css visible from
2922 * CSS ID functions. This pointer will be dereferened
2923 * from RCU-read-side without locks.
2926 rcu_assign_pointer(css
->id
->css
, css
);
2932 static void init_cgroup_css(struct cgroup_subsys_state
*css
,
2933 struct cgroup_subsys
*ss
,
2934 struct cgroup
*cgrp
)
2937 atomic_set(&css
->refcnt
, 1);
2940 if (cgrp
== dummytop
)
2941 set_bit(CSS_ROOT
, &css
->flags
);
2942 BUG_ON(cgrp
->subsys
[ss
->subsys_id
]);
2943 cgrp
->subsys
[ss
->subsys_id
] = css
;
2946 static void cgroup_lock_hierarchy(struct cgroupfs_root
*root
)
2948 /* We need to take each hierarchy_mutex in a consistent order */
2952 * No worry about a race with rebind_subsystems that might mess up the
2953 * locking order, since both parties are under cgroup_mutex.
2955 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2956 struct cgroup_subsys
*ss
= subsys
[i
];
2959 if (ss
->root
== root
)
2960 mutex_lock(&ss
->hierarchy_mutex
);
2964 static void cgroup_unlock_hierarchy(struct cgroupfs_root
*root
)
2968 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2969 struct cgroup_subsys
*ss
= subsys
[i
];
2972 if (ss
->root
== root
)
2973 mutex_unlock(&ss
->hierarchy_mutex
);
2978 * cgroup_create - create a cgroup
2979 * @parent: cgroup that will be parent of the new cgroup
2980 * @dentry: dentry of the new cgroup
2981 * @mode: mode to set on new inode
2983 * Must be called with the mutex on the parent inode held
2985 static long cgroup_create(struct cgroup
*parent
, struct dentry
*dentry
,
2988 struct cgroup
*cgrp
;
2989 struct cgroupfs_root
*root
= parent
->root
;
2991 struct cgroup_subsys
*ss
;
2992 struct super_block
*sb
= root
->sb
;
2994 cgrp
= kzalloc(sizeof(*cgrp
), GFP_KERNEL
);
2998 /* Grab a reference on the superblock so the hierarchy doesn't
2999 * get deleted on unmount if there are child cgroups. This
3000 * can be done outside cgroup_mutex, since the sb can't
3001 * disappear while someone has an open control file on the
3003 atomic_inc(&sb
->s_active
);
3005 mutex_lock(&cgroup_mutex
);
3007 init_cgroup_housekeeping(cgrp
);
3009 cgrp
->parent
= parent
;
3010 cgrp
->root
= parent
->root
;
3011 cgrp
->top_cgroup
= parent
->top_cgroup
;
3013 if (notify_on_release(parent
))
3014 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
3016 for_each_subsys(root
, ss
) {
3017 struct cgroup_subsys_state
*css
= ss
->create(ss
, cgrp
);
3023 init_cgroup_css(css
, ss
, cgrp
);
3025 err
= alloc_css_id(ss
, parent
, cgrp
);
3029 /* At error, ->destroy() callback has to free assigned ID. */
3032 cgroup_lock_hierarchy(root
);
3033 list_add(&cgrp
->sibling
, &cgrp
->parent
->children
);
3034 cgroup_unlock_hierarchy(root
);
3035 root
->number_of_cgroups
++;
3037 err
= cgroup_create_dir(cgrp
, dentry
, mode
);
3041 /* The cgroup directory was pre-locked for us */
3042 BUG_ON(!mutex_is_locked(&cgrp
->dentry
->d_inode
->i_mutex
));
3044 err
= cgroup_populate_dir(cgrp
);
3045 /* If err < 0, we have a half-filled directory - oh well ;) */
3047 mutex_unlock(&cgroup_mutex
);
3048 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
3054 cgroup_lock_hierarchy(root
);
3055 list_del(&cgrp
->sibling
);
3056 cgroup_unlock_hierarchy(root
);
3057 root
->number_of_cgroups
--;
3061 for_each_subsys(root
, ss
) {
3062 if (cgrp
->subsys
[ss
->subsys_id
])
3063 ss
->destroy(ss
, cgrp
);
3066 mutex_unlock(&cgroup_mutex
);
3068 /* Release the reference count that we took on the superblock */
3069 deactivate_super(sb
);
3075 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
3077 struct cgroup
*c_parent
= dentry
->d_parent
->d_fsdata
;
3079 /* the vfs holds inode->i_mutex already */
3080 return cgroup_create(c_parent
, dentry
, mode
| S_IFDIR
);
3083 static int cgroup_has_css_refs(struct cgroup
*cgrp
)
3085 /* Check the reference count on each subsystem. Since we
3086 * already established that there are no tasks in the
3087 * cgroup, if the css refcount is also 1, then there should
3088 * be no outstanding references, so the subsystem is safe to
3089 * destroy. We scan across all subsystems rather than using
3090 * the per-hierarchy linked list of mounted subsystems since
3091 * we can be called via check_for_release() with no
3092 * synchronization other than RCU, and the subsystem linked
3093 * list isn't RCU-safe */
3096 * We won't need to lock the subsys array, because the subsystems
3097 * we're concerned about aren't going anywhere since our cgroup root
3098 * has a reference on them.
3100 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
3101 struct cgroup_subsys
*ss
= subsys
[i
];
3102 struct cgroup_subsys_state
*css
;
3103 /* Skip subsystems not present or not in this hierarchy */
3104 if (ss
== NULL
|| ss
->root
!= cgrp
->root
)
3106 css
= cgrp
->subsys
[ss
->subsys_id
];
3107 /* When called from check_for_release() it's possible
3108 * that by this point the cgroup has been removed
3109 * and the css deleted. But a false-positive doesn't
3110 * matter, since it can only happen if the cgroup
3111 * has been deleted and hence no longer needs the
3112 * release agent to be called anyway. */
3113 if (css
&& (atomic_read(&css
->refcnt
) > 1))
3120 * Atomically mark all (or else none) of the cgroup's CSS objects as
3121 * CSS_REMOVED. Return true on success, or false if the cgroup has
3122 * busy subsystems. Call with cgroup_mutex held
3125 static int cgroup_clear_css_refs(struct cgroup
*cgrp
)
3127 struct cgroup_subsys
*ss
;
3128 unsigned long flags
;
3129 bool failed
= false;
3130 local_irq_save(flags
);
3131 for_each_subsys(cgrp
->root
, ss
) {
3132 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
3135 /* We can only remove a CSS with a refcnt==1 */
3136 refcnt
= atomic_read(&css
->refcnt
);
3143 * Drop the refcnt to 0 while we check other
3144 * subsystems. This will cause any racing
3145 * css_tryget() to spin until we set the
3146 * CSS_REMOVED bits or abort
3148 if (atomic_cmpxchg(&css
->refcnt
, refcnt
, 0) == refcnt
)
3154 for_each_subsys(cgrp
->root
, ss
) {
3155 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
3158 * Restore old refcnt if we previously managed
3159 * to clear it from 1 to 0
3161 if (!atomic_read(&css
->refcnt
))
3162 atomic_set(&css
->refcnt
, 1);
3164 /* Commit the fact that the CSS is removed */
3165 set_bit(CSS_REMOVED
, &css
->flags
);
3168 local_irq_restore(flags
);
3172 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
)
3174 struct cgroup
*cgrp
= dentry
->d_fsdata
;
3176 struct cgroup
*parent
;
3180 /* the vfs holds both inode->i_mutex already */
3182 mutex_lock(&cgroup_mutex
);
3183 if (atomic_read(&cgrp
->count
) != 0) {
3184 mutex_unlock(&cgroup_mutex
);
3187 if (!list_empty(&cgrp
->children
)) {
3188 mutex_unlock(&cgroup_mutex
);
3191 mutex_unlock(&cgroup_mutex
);
3194 * In general, subsystem has no css->refcnt after pre_destroy(). But
3195 * in racy cases, subsystem may have to get css->refcnt after
3196 * pre_destroy() and it makes rmdir return with -EBUSY. This sometimes
3197 * make rmdir return -EBUSY too often. To avoid that, we use waitqueue
3198 * for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir
3199 * and subsystem's reference count handling. Please see css_get/put
3200 * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation.
3202 set_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
);
3205 * Call pre_destroy handlers of subsys. Notify subsystems
3206 * that rmdir() request comes.
3208 ret
= cgroup_call_pre_destroy(cgrp
);
3210 clear_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
);
3214 mutex_lock(&cgroup_mutex
);
3215 parent
= cgrp
->parent
;
3216 if (atomic_read(&cgrp
->count
) || !list_empty(&cgrp
->children
)) {
3217 clear_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
);
3218 mutex_unlock(&cgroup_mutex
);
3221 prepare_to_wait(&cgroup_rmdir_waitq
, &wait
, TASK_INTERRUPTIBLE
);
3222 if (!cgroup_clear_css_refs(cgrp
)) {
3223 mutex_unlock(&cgroup_mutex
);
3225 * Because someone may call cgroup_wakeup_rmdir_waiter() before
3226 * prepare_to_wait(), we need to check this flag.
3228 if (test_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
))
3230 finish_wait(&cgroup_rmdir_waitq
, &wait
);
3231 clear_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
);
3232 if (signal_pending(current
))
3236 /* NO css_tryget() can success after here. */
3237 finish_wait(&cgroup_rmdir_waitq
, &wait
);
3238 clear_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
);
3240 spin_lock(&release_list_lock
);
3241 set_bit(CGRP_REMOVED
, &cgrp
->flags
);
3242 if (!list_empty(&cgrp
->release_list
))
3243 list_del(&cgrp
->release_list
);
3244 spin_unlock(&release_list_lock
);
3246 cgroup_lock_hierarchy(cgrp
->root
);
3247 /* delete this cgroup from parent->children */
3248 list_del(&cgrp
->sibling
);
3249 cgroup_unlock_hierarchy(cgrp
->root
);
3251 spin_lock(&cgrp
->dentry
->d_lock
);
3252 d
= dget(cgrp
->dentry
);
3253 spin_unlock(&d
->d_lock
);
3255 cgroup_d_remove_dir(d
);
3258 set_bit(CGRP_RELEASABLE
, &parent
->flags
);
3259 check_for_release(parent
);
3261 mutex_unlock(&cgroup_mutex
);
3265 static void __init
cgroup_init_subsys(struct cgroup_subsys
*ss
)
3267 struct cgroup_subsys_state
*css
;
3269 printk(KERN_INFO
"Initializing cgroup subsys %s\n", ss
->name
);
3271 /* Create the top cgroup state for this subsystem */
3272 list_add(&ss
->sibling
, &rootnode
.subsys_list
);
3273 ss
->root
= &rootnode
;
3274 css
= ss
->create(ss
, dummytop
);
3275 /* We don't handle early failures gracefully */
3276 BUG_ON(IS_ERR(css
));
3277 init_cgroup_css(css
, ss
, dummytop
);
3279 /* Update the init_css_set to contain a subsys
3280 * pointer to this state - since the subsystem is
3281 * newly registered, all tasks and hence the
3282 * init_css_set is in the subsystem's top cgroup. */
3283 init_css_set
.subsys
[ss
->subsys_id
] = dummytop
->subsys
[ss
->subsys_id
];
3285 need_forkexit_callback
|= ss
->fork
|| ss
->exit
;
3287 /* At system boot, before all subsystems have been
3288 * registered, no tasks have been forked, so we don't
3289 * need to invoke fork callbacks here. */
3290 BUG_ON(!list_empty(&init_task
.tasks
));
3292 mutex_init(&ss
->hierarchy_mutex
);
3293 lockdep_set_class(&ss
->hierarchy_mutex
, &ss
->subsys_key
);
3298 * cgroup_init_early - cgroup initialization at system boot
3300 * Initialize cgroups at system boot, and initialize any
3301 * subsystems that request early init.
3303 int __init
cgroup_init_early(void)
3306 atomic_set(&init_css_set
.refcount
, 1);
3307 INIT_LIST_HEAD(&init_css_set
.cg_links
);
3308 INIT_LIST_HEAD(&init_css_set
.tasks
);
3309 INIT_HLIST_NODE(&init_css_set
.hlist
);
3311 init_cgroup_root(&rootnode
);
3313 init_task
.cgroups
= &init_css_set
;
3315 init_css_set_link
.cg
= &init_css_set
;
3316 init_css_set_link
.cgrp
= dummytop
;
3317 list_add(&init_css_set_link
.cgrp_link_list
,
3318 &rootnode
.top_cgroup
.css_sets
);
3319 list_add(&init_css_set_link
.cg_link_list
,
3320 &init_css_set
.cg_links
);
3322 for (i
= 0; i
< CSS_SET_TABLE_SIZE
; i
++)
3323 INIT_HLIST_HEAD(&css_set_table
[i
]);
3325 /* at bootup time, we don't worry about modular subsystems */
3326 for (i
= 0; i
< CGROUP_BUILTIN_SUBSYS_COUNT
; i
++) {
3327 struct cgroup_subsys
*ss
= subsys
[i
];
3330 BUG_ON(strlen(ss
->name
) > MAX_CGROUP_TYPE_NAMELEN
);
3331 BUG_ON(!ss
->create
);
3332 BUG_ON(!ss
->destroy
);
3333 if (ss
->subsys_id
!= i
) {
3334 printk(KERN_ERR
"cgroup: Subsys %s id == %d\n",
3335 ss
->name
, ss
->subsys_id
);
3340 cgroup_init_subsys(ss
);
3346 * cgroup_init - cgroup initialization
3348 * Register cgroup filesystem and /proc file, and initialize
3349 * any subsystems that didn't request early init.
3351 int __init
cgroup_init(void)
3355 struct hlist_head
*hhead
;
3357 err
= bdi_init(&cgroup_backing_dev_info
);
3361 /* at bootup time, we don't worry about modular subsystems */
3362 for (i
= 0; i
< CGROUP_BUILTIN_SUBSYS_COUNT
; i
++) {
3363 struct cgroup_subsys
*ss
= subsys
[i
];
3364 if (!ss
->early_init
)
3365 cgroup_init_subsys(ss
);
3367 cgroup_subsys_init_idr(ss
);
3370 /* Add init_css_set to the hash table */
3371 hhead
= css_set_hash(init_css_set
.subsys
);
3372 hlist_add_head(&init_css_set
.hlist
, hhead
);
3373 BUG_ON(!init_root_id(&rootnode
));
3374 err
= register_filesystem(&cgroup_fs_type
);
3378 proc_create("cgroups", 0, NULL
, &proc_cgroupstats_operations
);
3382 bdi_destroy(&cgroup_backing_dev_info
);
3388 * proc_cgroup_show()
3389 * - Print task's cgroup paths into seq_file, one line for each hierarchy
3390 * - Used for /proc/<pid>/cgroup.
3391 * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
3392 * doesn't really matter if tsk->cgroup changes after we read it,
3393 * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
3394 * anyway. No need to check that tsk->cgroup != NULL, thanks to
3395 * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
3396 * cgroup to top_cgroup.
3399 /* TODO: Use a proper seq_file iterator */
3400 static int proc_cgroup_show(struct seq_file
*m
, void *v
)
3403 struct task_struct
*tsk
;
3406 struct cgroupfs_root
*root
;
3409 buf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
3415 tsk
= get_pid_task(pid
, PIDTYPE_PID
);
3421 mutex_lock(&cgroup_mutex
);
3423 for_each_active_root(root
) {
3424 struct cgroup_subsys
*ss
;
3425 struct cgroup
*cgrp
;
3428 seq_printf(m
, "%d:", root
->hierarchy_id
);
3429 for_each_subsys(root
, ss
)
3430 seq_printf(m
, "%s%s", count
++ ? "," : "", ss
->name
);
3431 if (strlen(root
->name
))
3432 seq_printf(m
, "%sname=%s", count
? "," : "",
3435 cgrp
= task_cgroup_from_root(tsk
, root
);
3436 retval
= cgroup_path(cgrp
, buf
, PAGE_SIZE
);
3444 mutex_unlock(&cgroup_mutex
);
3445 put_task_struct(tsk
);
3452 static int cgroup_open(struct inode
*inode
, struct file
*file
)
3454 struct pid
*pid
= PROC_I(inode
)->pid
;
3455 return single_open(file
, proc_cgroup_show
, pid
);
3458 const struct file_operations proc_cgroup_operations
= {
3459 .open
= cgroup_open
,
3461 .llseek
= seq_lseek
,
3462 .release
= single_release
,
3465 /* Display information about each subsystem and each hierarchy */
3466 static int proc_cgroupstats_show(struct seq_file
*m
, void *v
)
3470 seq_puts(m
, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
3472 * ideally we don't want subsystems moving around while we do this.
3473 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
3474 * subsys/hierarchy state.
3476 mutex_lock(&cgroup_mutex
);
3477 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
3478 struct cgroup_subsys
*ss
= subsys
[i
];
3481 seq_printf(m
, "%s\t%d\t%d\t%d\n",
3482 ss
->name
, ss
->root
->hierarchy_id
,
3483 ss
->root
->number_of_cgroups
, !ss
->disabled
);
3485 mutex_unlock(&cgroup_mutex
);
3489 static int cgroupstats_open(struct inode
*inode
, struct file
*file
)
3491 return single_open(file
, proc_cgroupstats_show
, NULL
);
3494 static const struct file_operations proc_cgroupstats_operations
= {
3495 .open
= cgroupstats_open
,
3497 .llseek
= seq_lseek
,
3498 .release
= single_release
,
3502 * cgroup_fork - attach newly forked task to its parents cgroup.
3503 * @child: pointer to task_struct of forking parent process.
3505 * Description: A task inherits its parent's cgroup at fork().
3507 * A pointer to the shared css_set was automatically copied in
3508 * fork.c by dup_task_struct(). However, we ignore that copy, since
3509 * it was not made under the protection of RCU or cgroup_mutex, so
3510 * might no longer be a valid cgroup pointer. cgroup_attach_task() might
3511 * have already changed current->cgroups, allowing the previously
3512 * referenced cgroup group to be removed and freed.
3514 * At the point that cgroup_fork() is called, 'current' is the parent
3515 * task, and the passed argument 'child' points to the child task.
3517 void cgroup_fork(struct task_struct
*child
)
3520 child
->cgroups
= current
->cgroups
;
3521 get_css_set(child
->cgroups
);
3522 task_unlock(current
);
3523 INIT_LIST_HEAD(&child
->cg_list
);
3527 * cgroup_fork_callbacks - run fork callbacks
3528 * @child: the new task
3530 * Called on a new task very soon before adding it to the
3531 * tasklist. No need to take any locks since no-one can
3532 * be operating on this task.
3534 void cgroup_fork_callbacks(struct task_struct
*child
)
3536 if (need_forkexit_callback
) {
3539 * forkexit callbacks are only supported for builtin
3540 * subsystems, and the builtin section of the subsys array is
3541 * immutable, so we don't need to lock the subsys array here.
3543 for (i
= 0; i
< CGROUP_BUILTIN_SUBSYS_COUNT
; i
++) {
3544 struct cgroup_subsys
*ss
= subsys
[i
];
3546 ss
->fork(ss
, child
);
3552 * cgroup_post_fork - called on a new task after adding it to the task list
3553 * @child: the task in question
3555 * Adds the task to the list running through its css_set if necessary.
3556 * Has to be after the task is visible on the task list in case we race
3557 * with the first call to cgroup_iter_start() - to guarantee that the
3558 * new task ends up on its list.
3560 void cgroup_post_fork(struct task_struct
*child
)
3562 if (use_task_css_set_links
) {
3563 write_lock(&css_set_lock
);
3565 if (list_empty(&child
->cg_list
))
3566 list_add(&child
->cg_list
, &child
->cgroups
->tasks
);
3568 write_unlock(&css_set_lock
);
3572 * cgroup_exit - detach cgroup from exiting task
3573 * @tsk: pointer to task_struct of exiting process
3574 * @run_callback: run exit callbacks?
3576 * Description: Detach cgroup from @tsk and release it.
3578 * Note that cgroups marked notify_on_release force every task in
3579 * them to take the global cgroup_mutex mutex when exiting.
3580 * This could impact scaling on very large systems. Be reluctant to
3581 * use notify_on_release cgroups where very high task exit scaling
3582 * is required on large systems.
3584 * the_top_cgroup_hack:
3586 * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
3588 * We call cgroup_exit() while the task is still competent to
3589 * handle notify_on_release(), then leave the task attached to the
3590 * root cgroup in each hierarchy for the remainder of its exit.
3592 * To do this properly, we would increment the reference count on
3593 * top_cgroup, and near the very end of the kernel/exit.c do_exit()
3594 * code we would add a second cgroup function call, to drop that
3595 * reference. This would just create an unnecessary hot spot on
3596 * the top_cgroup reference count, to no avail.
3598 * Normally, holding a reference to a cgroup without bumping its
3599 * count is unsafe. The cgroup could go away, or someone could
3600 * attach us to a different cgroup, decrementing the count on
3601 * the first cgroup that we never incremented. But in this case,
3602 * top_cgroup isn't going away, and either task has PF_EXITING set,
3603 * which wards off any cgroup_attach_task() attempts, or task is a failed
3604 * fork, never visible to cgroup_attach_task.
3606 void cgroup_exit(struct task_struct
*tsk
, int run_callbacks
)
3611 if (run_callbacks
&& need_forkexit_callback
) {
3613 * modular subsystems can't use callbacks, so no need to lock
3616 for (i
= 0; i
< CGROUP_BUILTIN_SUBSYS_COUNT
; i
++) {
3617 struct cgroup_subsys
*ss
= subsys
[i
];
3624 * Unlink from the css_set task list if necessary.
3625 * Optimistically check cg_list before taking
3628 if (!list_empty(&tsk
->cg_list
)) {
3629 write_lock(&css_set_lock
);
3630 if (!list_empty(&tsk
->cg_list
))
3631 list_del(&tsk
->cg_list
);
3632 write_unlock(&css_set_lock
);
3635 /* Reassign the task to the init_css_set. */
3638 tsk
->cgroups
= &init_css_set
;
3641 put_css_set_taskexit(cg
);
3645 * cgroup_clone - clone the cgroup the given subsystem is attached to
3646 * @tsk: the task to be moved
3647 * @subsys: the given subsystem
3648 * @nodename: the name for the new cgroup
3650 * Duplicate the current cgroup in the hierarchy that the given
3651 * subsystem is attached to, and move this task into the new
3654 int cgroup_clone(struct task_struct
*tsk
, struct cgroup_subsys
*subsys
,
3657 struct dentry
*dentry
;
3659 struct cgroup
*parent
, *child
;
3660 struct inode
*inode
;
3662 struct cgroupfs_root
*root
;
3663 struct cgroup_subsys
*ss
;
3665 /* We shouldn't be called by an unregistered subsystem */
3666 BUG_ON(!subsys
->active
);
3668 /* First figure out what hierarchy and cgroup we're dealing
3669 * with, and pin them so we can drop cgroup_mutex */
3670 mutex_lock(&cgroup_mutex
);
3672 root
= subsys
->root
;
3673 if (root
== &rootnode
) {
3674 mutex_unlock(&cgroup_mutex
);
3678 /* Pin the hierarchy */
3679 if (!atomic_inc_not_zero(&root
->sb
->s_active
)) {
3680 /* We race with the final deactivate_super() */
3681 mutex_unlock(&cgroup_mutex
);
3685 /* Keep the cgroup alive */
3687 parent
= task_cgroup(tsk
, subsys
->subsys_id
);
3692 mutex_unlock(&cgroup_mutex
);
3694 /* Now do the VFS work to create a cgroup */
3695 inode
= parent
->dentry
->d_inode
;
3697 /* Hold the parent directory mutex across this operation to
3698 * stop anyone else deleting the new cgroup */
3699 mutex_lock(&inode
->i_mutex
);
3700 dentry
= lookup_one_len(nodename
, parent
->dentry
, strlen(nodename
));
3701 if (IS_ERR(dentry
)) {
3703 "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename
,
3705 ret
= PTR_ERR(dentry
);
3709 /* Create the cgroup directory, which also creates the cgroup */
3710 ret
= vfs_mkdir(inode
, dentry
, 0755);
3711 child
= __d_cgrp(dentry
);
3715 "Failed to create cgroup %s: %d\n", nodename
,
3720 /* The cgroup now exists. Retake cgroup_mutex and check
3721 * that we're still in the same state that we thought we
3723 mutex_lock(&cgroup_mutex
);
3724 if ((root
!= subsys
->root
) ||
3725 (parent
!= task_cgroup(tsk
, subsys
->subsys_id
))) {
3726 /* Aargh, we raced ... */
3727 mutex_unlock(&inode
->i_mutex
);
3730 deactivate_super(root
->sb
);
3731 /* The cgroup is still accessible in the VFS, but
3732 * we're not going to try to rmdir() it at this
3735 "Race in cgroup_clone() - leaking cgroup %s\n",
3740 /* do any required auto-setup */
3741 for_each_subsys(root
, ss
) {
3743 ss
->post_clone(ss
, child
);
3746 /* All seems fine. Finish by moving the task into the new cgroup */
3747 ret
= cgroup_attach_task(child
, tsk
);
3748 mutex_unlock(&cgroup_mutex
);
3751 mutex_unlock(&inode
->i_mutex
);
3753 mutex_lock(&cgroup_mutex
);
3755 mutex_unlock(&cgroup_mutex
);
3756 deactivate_super(root
->sb
);
3761 * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp
3762 * @cgrp: the cgroup in question
3763 * @task: the task in question
3765 * See if @cgrp is a descendant of @task's cgroup in the appropriate
3768 * If we are sending in dummytop, then presumably we are creating
3769 * the top cgroup in the subsystem.
3771 * Called only by the ns (nsproxy) cgroup.
3773 int cgroup_is_descendant(const struct cgroup
*cgrp
, struct task_struct
*task
)
3776 struct cgroup
*target
;
3778 if (cgrp
== dummytop
)
3781 target
= task_cgroup_from_root(task
, cgrp
->root
);
3782 while (cgrp
!= target
&& cgrp
!= cgrp
->top_cgroup
)
3783 cgrp
= cgrp
->parent
;
3784 ret
= (cgrp
== target
);
3788 static void check_for_release(struct cgroup
*cgrp
)
3790 /* All of these checks rely on RCU to keep the cgroup
3791 * structure alive */
3792 if (cgroup_is_releasable(cgrp
) && !atomic_read(&cgrp
->count
)
3793 && list_empty(&cgrp
->children
) && !cgroup_has_css_refs(cgrp
)) {
3794 /* Control Group is currently removeable. If it's not
3795 * already queued for a userspace notification, queue
3797 int need_schedule_work
= 0;
3798 spin_lock(&release_list_lock
);
3799 if (!cgroup_is_removed(cgrp
) &&
3800 list_empty(&cgrp
->release_list
)) {
3801 list_add(&cgrp
->release_list
, &release_list
);
3802 need_schedule_work
= 1;
3804 spin_unlock(&release_list_lock
);
3805 if (need_schedule_work
)
3806 schedule_work(&release_agent_work
);
3810 /* Caller must verify that the css is not for root cgroup */
3811 void __css_put(struct cgroup_subsys_state
*css
, int count
)
3813 struct cgroup
*cgrp
= css
->cgroup
;
3816 val
= atomic_sub_return(count
, &css
->refcnt
);
3818 if (notify_on_release(cgrp
)) {
3819 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
3820 check_for_release(cgrp
);
3822 cgroup_wakeup_rmdir_waiter(cgrp
);
3825 WARN_ON_ONCE(val
< 1);
3829 * Notify userspace when a cgroup is released, by running the
3830 * configured release agent with the name of the cgroup (path
3831 * relative to the root of cgroup file system) as the argument.
3833 * Most likely, this user command will try to rmdir this cgroup.
3835 * This races with the possibility that some other task will be
3836 * attached to this cgroup before it is removed, or that some other
3837 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
3838 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
3839 * unused, and this cgroup will be reprieved from its death sentence,
3840 * to continue to serve a useful existence. Next time it's released,
3841 * we will get notified again, if it still has 'notify_on_release' set.
3843 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
3844 * means only wait until the task is successfully execve()'d. The
3845 * separate release agent task is forked by call_usermodehelper(),
3846 * then control in this thread returns here, without waiting for the
3847 * release agent task. We don't bother to wait because the caller of
3848 * this routine has no use for the exit status of the release agent
3849 * task, so no sense holding our caller up for that.
3851 static void cgroup_release_agent(struct work_struct
*work
)
3853 BUG_ON(work
!= &release_agent_work
);
3854 mutex_lock(&cgroup_mutex
);
3855 spin_lock(&release_list_lock
);
3856 while (!list_empty(&release_list
)) {
3857 char *argv
[3], *envp
[3];
3859 char *pathbuf
= NULL
, *agentbuf
= NULL
;
3860 struct cgroup
*cgrp
= list_entry(release_list
.next
,
3863 list_del_init(&cgrp
->release_list
);
3864 spin_unlock(&release_list_lock
);
3865 pathbuf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
3868 if (cgroup_path(cgrp
, pathbuf
, PAGE_SIZE
) < 0)
3870 agentbuf
= kstrdup(cgrp
->root
->release_agent_path
, GFP_KERNEL
);
3875 argv
[i
++] = agentbuf
;
3876 argv
[i
++] = pathbuf
;
3880 /* minimal command environment */
3881 envp
[i
++] = "HOME=/";
3882 envp
[i
++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
3885 /* Drop the lock while we invoke the usermode helper,
3886 * since the exec could involve hitting disk and hence
3887 * be a slow process */
3888 mutex_unlock(&cgroup_mutex
);
3889 call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_EXEC
);
3890 mutex_lock(&cgroup_mutex
);
3894 spin_lock(&release_list_lock
);
3896 spin_unlock(&release_list_lock
);
3897 mutex_unlock(&cgroup_mutex
);
3900 static int __init
cgroup_disable(char *str
)
3905 while ((token
= strsep(&str
, ",")) != NULL
) {
3909 * cgroup_disable, being at boot time, can't know about module
3910 * subsystems, so we don't worry about them.
3912 for (i
= 0; i
< CGROUP_BUILTIN_SUBSYS_COUNT
; i
++) {
3913 struct cgroup_subsys
*ss
= subsys
[i
];
3915 if (!strcmp(token
, ss
->name
)) {
3917 printk(KERN_INFO
"Disabling %s control group"
3918 " subsystem\n", ss
->name
);
3925 __setup("cgroup_disable=", cgroup_disable
);
3928 * Functons for CSS ID.
3932 *To get ID other than 0, this should be called when !cgroup_is_removed().
3934 unsigned short css_id(struct cgroup_subsys_state
*css
)
3936 struct css_id
*cssid
= rcu_dereference(css
->id
);
3943 unsigned short css_depth(struct cgroup_subsys_state
*css
)
3945 struct css_id
*cssid
= rcu_dereference(css
->id
);
3948 return cssid
->depth
;
3952 bool css_is_ancestor(struct cgroup_subsys_state
*child
,
3953 const struct cgroup_subsys_state
*root
)
3955 struct css_id
*child_id
= rcu_dereference(child
->id
);
3956 struct css_id
*root_id
= rcu_dereference(root
->id
);
3958 if (!child_id
|| !root_id
|| (child_id
->depth
< root_id
->depth
))
3960 return child_id
->stack
[root_id
->depth
] == root_id
->id
;
3963 static void __free_css_id_cb(struct rcu_head
*head
)
3967 id
= container_of(head
, struct css_id
, rcu_head
);
3971 void free_css_id(struct cgroup_subsys
*ss
, struct cgroup_subsys_state
*css
)
3973 struct css_id
*id
= css
->id
;
3974 /* When this is called before css_id initialization, id can be NULL */
3978 BUG_ON(!ss
->use_id
);
3980 rcu_assign_pointer(id
->css
, NULL
);
3981 rcu_assign_pointer(css
->id
, NULL
);
3982 spin_lock(&ss
->id_lock
);
3983 idr_remove(&ss
->idr
, id
->id
);
3984 spin_unlock(&ss
->id_lock
);
3985 call_rcu(&id
->rcu_head
, __free_css_id_cb
);
3989 * This is called by init or create(). Then, calls to this function are
3990 * always serialized (By cgroup_mutex() at create()).
3993 static struct css_id
*get_new_cssid(struct cgroup_subsys
*ss
, int depth
)
3995 struct css_id
*newid
;
3996 int myid
, error
, size
;
3998 BUG_ON(!ss
->use_id
);
4000 size
= sizeof(*newid
) + sizeof(unsigned short) * (depth
+ 1);
4001 newid
= kzalloc(size
, GFP_KERNEL
);
4003 return ERR_PTR(-ENOMEM
);
4005 if (unlikely(!idr_pre_get(&ss
->idr
, GFP_KERNEL
))) {
4009 spin_lock(&ss
->id_lock
);
4010 /* Don't use 0. allocates an ID of 1-65535 */
4011 error
= idr_get_new_above(&ss
->idr
, newid
, 1, &myid
);
4012 spin_unlock(&ss
->id_lock
);
4014 /* Returns error when there are no free spaces for new ID.*/
4019 if (myid
> CSS_ID_MAX
)
4023 newid
->depth
= depth
;
4027 spin_lock(&ss
->id_lock
);
4028 idr_remove(&ss
->idr
, myid
);
4029 spin_unlock(&ss
->id_lock
);
4032 return ERR_PTR(error
);
4036 static int __init
cgroup_subsys_init_idr(struct cgroup_subsys
*ss
)
4038 struct css_id
*newid
;
4039 struct cgroup_subsys_state
*rootcss
;
4041 spin_lock_init(&ss
->id_lock
);
4044 rootcss
= init_css_set
.subsys
[ss
->subsys_id
];
4045 newid
= get_new_cssid(ss
, 0);
4047 return PTR_ERR(newid
);
4049 newid
->stack
[0] = newid
->id
;
4050 newid
->css
= rootcss
;
4051 rootcss
->id
= newid
;
4055 static int alloc_css_id(struct cgroup_subsys
*ss
, struct cgroup
*parent
,
4056 struct cgroup
*child
)
4058 int subsys_id
, i
, depth
= 0;
4059 struct cgroup_subsys_state
*parent_css
, *child_css
;
4060 struct css_id
*child_id
, *parent_id
= NULL
;
4062 subsys_id
= ss
->subsys_id
;
4063 parent_css
= parent
->subsys
[subsys_id
];
4064 child_css
= child
->subsys
[subsys_id
];
4065 depth
= css_depth(parent_css
) + 1;
4066 parent_id
= parent_css
->id
;
4068 child_id
= get_new_cssid(ss
, depth
);
4069 if (IS_ERR(child_id
))
4070 return PTR_ERR(child_id
);
4072 for (i
= 0; i
< depth
; i
++)
4073 child_id
->stack
[i
] = parent_id
->stack
[i
];
4074 child_id
->stack
[depth
] = child_id
->id
;
4076 * child_id->css pointer will be set after this cgroup is available
4077 * see cgroup_populate_dir()
4079 rcu_assign_pointer(child_css
->id
, child_id
);
4085 * css_lookup - lookup css by id
4086 * @ss: cgroup subsys to be looked into.
4089 * Returns pointer to cgroup_subsys_state if there is valid one with id.
4090 * NULL if not. Should be called under rcu_read_lock()
4092 struct cgroup_subsys_state
*css_lookup(struct cgroup_subsys
*ss
, int id
)
4094 struct css_id
*cssid
= NULL
;
4096 BUG_ON(!ss
->use_id
);
4097 cssid
= idr_find(&ss
->idr
, id
);
4099 if (unlikely(!cssid
))
4102 return rcu_dereference(cssid
->css
);
4106 * css_get_next - lookup next cgroup under specified hierarchy.
4107 * @ss: pointer to subsystem
4108 * @id: current position of iteration.
4109 * @root: pointer to css. search tree under this.
4110 * @foundid: position of found object.
4112 * Search next css under the specified hierarchy of rootid. Calling under
4113 * rcu_read_lock() is necessary. Returns NULL if it reaches the end.
4115 struct cgroup_subsys_state
*
4116 css_get_next(struct cgroup_subsys
*ss
, int id
,
4117 struct cgroup_subsys_state
*root
, int *foundid
)
4119 struct cgroup_subsys_state
*ret
= NULL
;
4122 int rootid
= css_id(root
);
4123 int depth
= css_depth(root
);
4128 BUG_ON(!ss
->use_id
);
4129 /* fill start point for scan */
4133 * scan next entry from bitmap(tree), tmpid is updated after
4136 spin_lock(&ss
->id_lock
);
4137 tmp
= idr_get_next(&ss
->idr
, &tmpid
);
4138 spin_unlock(&ss
->id_lock
);
4142 if (tmp
->depth
>= depth
&& tmp
->stack
[depth
] == rootid
) {
4143 ret
= rcu_dereference(tmp
->css
);
4149 /* continue to scan from next id */
4155 #ifdef CONFIG_CGROUP_DEBUG
4156 static struct cgroup_subsys_state
*debug_create(struct cgroup_subsys
*ss
,
4157 struct cgroup
*cont
)
4159 struct cgroup_subsys_state
*css
= kzalloc(sizeof(*css
), GFP_KERNEL
);
4162 return ERR_PTR(-ENOMEM
);
4167 static void debug_destroy(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
4169 kfree(cont
->subsys
[debug_subsys_id
]);
4172 static u64
cgroup_refcount_read(struct cgroup
*cont
, struct cftype
*cft
)
4174 return atomic_read(&cont
->count
);
4177 static u64
debug_taskcount_read(struct cgroup
*cont
, struct cftype
*cft
)
4179 return cgroup_task_count(cont
);
4182 static u64
current_css_set_read(struct cgroup
*cont
, struct cftype
*cft
)
4184 return (u64
)(unsigned long)current
->cgroups
;
4187 static u64
current_css_set_refcount_read(struct cgroup
*cont
,
4193 count
= atomic_read(¤t
->cgroups
->refcount
);
4198 static int current_css_set_cg_links_read(struct cgroup
*cont
,
4200 struct seq_file
*seq
)
4202 struct cg_cgroup_link
*link
;
4205 read_lock(&css_set_lock
);
4207 cg
= rcu_dereference(current
->cgroups
);
4208 list_for_each_entry(link
, &cg
->cg_links
, cg_link_list
) {
4209 struct cgroup
*c
= link
->cgrp
;
4213 name
= c
->dentry
->d_name
.name
;
4216 seq_printf(seq
, "Root %d group %s\n",
4217 c
->root
->hierarchy_id
, name
);
4220 read_unlock(&css_set_lock
);
4224 #define MAX_TASKS_SHOWN_PER_CSS 25
4225 static int cgroup_css_links_read(struct cgroup
*cont
,
4227 struct seq_file
*seq
)
4229 struct cg_cgroup_link
*link
;
4231 read_lock(&css_set_lock
);
4232 list_for_each_entry(link
, &cont
->css_sets
, cgrp_link_list
) {
4233 struct css_set
*cg
= link
->cg
;
4234 struct task_struct
*task
;
4236 seq_printf(seq
, "css_set %p\n", cg
);
4237 list_for_each_entry(task
, &cg
->tasks
, cg_list
) {
4238 if (count
++ > MAX_TASKS_SHOWN_PER_CSS
) {
4239 seq_puts(seq
, " ...\n");
4242 seq_printf(seq
, " task %d\n",
4243 task_pid_vnr(task
));
4247 read_unlock(&css_set_lock
);
4251 static u64
releasable_read(struct cgroup
*cgrp
, struct cftype
*cft
)
4253 return test_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
4256 static struct cftype debug_files
[] = {
4258 .name
= "cgroup_refcount",
4259 .read_u64
= cgroup_refcount_read
,
4262 .name
= "taskcount",
4263 .read_u64
= debug_taskcount_read
,
4267 .name
= "current_css_set",
4268 .read_u64
= current_css_set_read
,
4272 .name
= "current_css_set_refcount",
4273 .read_u64
= current_css_set_refcount_read
,
4277 .name
= "current_css_set_cg_links",
4278 .read_seq_string
= current_css_set_cg_links_read
,
4282 .name
= "cgroup_css_links",
4283 .read_seq_string
= cgroup_css_links_read
,
4287 .name
= "releasable",
4288 .read_u64
= releasable_read
,
4292 static int debug_populate(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
4294 return cgroup_add_files(cont
, ss
, debug_files
,
4295 ARRAY_SIZE(debug_files
));
4298 struct cgroup_subsys debug_subsys
= {
4300 .create
= debug_create
,
4301 .destroy
= debug_destroy
,
4302 .populate
= debug_populate
,
4303 .subsys_id
= debug_subsys_id
,
4305 #endif /* CONFIG_CGROUP_DEBUG */