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/errno.h>
28 #include <linux/kernel.h>
29 #include <linux/list.h>
31 #include <linux/mutex.h>
32 #include <linux/mount.h>
33 #include <linux/pagemap.h>
34 #include <linux/proc_fs.h>
35 #include <linux/rcupdate.h>
36 #include <linux/sched.h>
37 #include <linux/backing-dev.h>
38 #include <linux/seq_file.h>
39 #include <linux/slab.h>
40 #include <linux/magic.h>
41 #include <linux/spinlock.h>
42 #include <linux/string.h>
43 #include <linux/sort.h>
44 #include <linux/kmod.h>
45 #include <linux/delayacct.h>
46 #include <linux/cgroupstats.h>
48 #include <asm/atomic.h>
50 static DEFINE_MUTEX(cgroup_mutex
);
52 /* Generate an array of cgroup subsystem pointers */
53 #define SUBSYS(_x) &_x ## _subsys,
55 static struct cgroup_subsys
*subsys
[] = {
56 #include <linux/cgroup_subsys.h>
60 * A cgroupfs_root represents the root of a cgroup hierarchy,
61 * and may be associated with a superblock to form an active
64 struct cgroupfs_root
{
65 struct super_block
*sb
;
68 * The bitmask of subsystems intended to be attached to this
71 unsigned long subsys_bits
;
73 /* The bitmask of subsystems currently attached to this hierarchy */
74 unsigned long actual_subsys_bits
;
76 /* A list running through the attached subsystems */
77 struct list_head subsys_list
;
79 /* The root cgroup for this hierarchy */
80 struct cgroup top_cgroup
;
82 /* Tracks how many cgroups are currently defined in hierarchy.*/
83 int number_of_cgroups
;
85 /* A list running through the mounted hierarchies */
86 struct list_head root_list
;
88 /* Hierarchy-specific flags */
91 /* The path to use for release notifications. No locking
92 * between setting and use - so if userspace updates this
93 * while child cgroups exist, you could miss a
94 * notification. We ensure that it's always a valid
95 * NUL-terminated string */
96 char release_agent_path
[PATH_MAX
];
101 * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
102 * subsystems that are otherwise unattached - it never has more than a
103 * single cgroup, and all tasks are part of that cgroup.
105 static struct cgroupfs_root rootnode
;
107 /* The list of hierarchy roots */
109 static LIST_HEAD(roots
);
110 static int root_count
;
112 /* dummytop is a shorthand for the dummy hierarchy's top cgroup */
113 #define dummytop (&rootnode.top_cgroup)
115 /* This flag indicates whether tasks in the fork and exit paths should
116 * check for fork/exit handlers to call. This avoids us having to do
117 * extra work in the fork/exit path if none of the subsystems need to
120 static int need_forkexit_callback
;
122 /* convenient tests for these bits */
123 inline int cgroup_is_removed(const struct cgroup
*cgrp
)
125 return test_bit(CGRP_REMOVED
, &cgrp
->flags
);
128 /* bits in struct cgroupfs_root flags field */
130 ROOT_NOPREFIX
, /* mounted subsystems have no named prefix */
133 static int cgroup_is_releasable(const struct cgroup
*cgrp
)
136 (1 << CGRP_RELEASABLE
) |
137 (1 << CGRP_NOTIFY_ON_RELEASE
);
138 return (cgrp
->flags
& bits
) == bits
;
141 static int notify_on_release(const struct cgroup
*cgrp
)
143 return test_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
147 * for_each_subsys() allows you to iterate on each subsystem attached to
148 * an active hierarchy
150 #define for_each_subsys(_root, _ss) \
151 list_for_each_entry(_ss, &_root->subsys_list, sibling)
153 /* for_each_root() allows you to iterate across the active hierarchies */
154 #define for_each_root(_root) \
155 list_for_each_entry(_root, &roots, root_list)
157 /* the list of cgroups eligible for automatic release. Protected by
158 * release_list_lock */
159 static LIST_HEAD(release_list
);
160 static DEFINE_SPINLOCK(release_list_lock
);
161 static void cgroup_release_agent(struct work_struct
*work
);
162 static DECLARE_WORK(release_agent_work
, cgroup_release_agent
);
163 static void check_for_release(struct cgroup
*cgrp
);
165 /* Link structure for associating css_set objects with cgroups */
166 struct cg_cgroup_link
{
168 * List running through cg_cgroup_links associated with a
169 * cgroup, anchored on cgroup->css_sets
171 struct list_head cgrp_link_list
;
173 * List running through cg_cgroup_links pointing at a
174 * single css_set object, anchored on css_set->cg_links
176 struct list_head cg_link_list
;
180 /* The default css_set - used by init and its children prior to any
181 * hierarchies being mounted. It contains a pointer to the root state
182 * for each subsystem. Also used to anchor the list of css_sets. Not
183 * reference-counted, to improve performance when child cgroups
184 * haven't been created.
187 static struct css_set init_css_set
;
188 static struct cg_cgroup_link init_css_set_link
;
190 /* css_set_lock protects the list of css_set objects, and the
191 * chain of tasks off each css_set. Nests outside task->alloc_lock
192 * due to cgroup_iter_start() */
193 static DEFINE_RWLOCK(css_set_lock
);
194 static int css_set_count
;
196 /* We don't maintain the lists running through each css_set to its
197 * task until after the first call to cgroup_iter_start(). This
198 * reduces the fork()/exit() overhead for people who have cgroups
199 * compiled into their kernel but not actually in use */
200 static int use_task_css_set_links
;
202 /* When we create or destroy a css_set, the operation simply
203 * takes/releases a reference count on all the cgroups referenced
204 * by subsystems in this css_set. This can end up multiple-counting
205 * some cgroups, but that's OK - the ref-count is just a
206 * busy/not-busy indicator; ensuring that we only count each cgroup
207 * once would require taking a global lock to ensure that no
208 * subsystems moved between hierarchies while we were doing so.
210 * Possible TODO: decide at boot time based on the number of
211 * registered subsystems and the number of CPUs or NUMA nodes whether
212 * it's better for performance to ref-count every subsystem, or to
213 * take a global lock and only add one ref count to each hierarchy.
217 * unlink a css_set from the list and free it
219 static void unlink_css_set(struct css_set
*cg
)
221 write_lock(&css_set_lock
);
224 while (!list_empty(&cg
->cg_links
)) {
225 struct cg_cgroup_link
*link
;
226 link
= list_entry(cg
->cg_links
.next
,
227 struct cg_cgroup_link
, cg_link_list
);
228 list_del(&link
->cg_link_list
);
229 list_del(&link
->cgrp_link_list
);
232 write_unlock(&css_set_lock
);
235 static void __release_css_set(struct kref
*k
, int taskexit
)
238 struct css_set
*cg
= container_of(k
, struct css_set
, ref
);
243 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
244 struct cgroup
*cgrp
= cg
->subsys
[i
]->cgroup
;
245 if (atomic_dec_and_test(&cgrp
->count
) &&
246 notify_on_release(cgrp
)) {
248 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
249 check_for_release(cgrp
);
256 static void release_css_set(struct kref
*k
)
258 __release_css_set(k
, 0);
261 static void release_css_set_taskexit(struct kref
*k
)
263 __release_css_set(k
, 1);
267 * refcounted get/put for css_set objects
269 static inline void get_css_set(struct css_set
*cg
)
274 static inline void put_css_set(struct css_set
*cg
)
276 kref_put(&cg
->ref
, release_css_set
);
279 static inline void put_css_set_taskexit(struct css_set
*cg
)
281 kref_put(&cg
->ref
, release_css_set_taskexit
);
285 * find_existing_css_set() is a helper for
286 * find_css_set(), and checks to see whether an existing
287 * css_set is suitable. This currently walks a linked-list for
288 * simplicity; a later patch will use a hash table for better
291 * oldcg: the cgroup group that we're using before the cgroup
294 * cgrp: the cgroup that we're moving into
296 * template: location in which to build the desired set of subsystem
297 * state objects for the new cgroup group
299 static struct css_set
*find_existing_css_set(
300 struct css_set
*oldcg
,
302 struct cgroup_subsys_state
*template[])
305 struct cgroupfs_root
*root
= cgrp
->root
;
306 struct list_head
*l
= &init_css_set
.list
;
308 /* Built the set of subsystem state objects that we want to
309 * see in the new css_set */
310 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
311 if (root
->subsys_bits
& (1UL << i
)) {
312 /* Subsystem is in this hierarchy. So we want
313 * the subsystem state from the new
315 template[i
] = cgrp
->subsys
[i
];
317 /* Subsystem is not in this hierarchy, so we
318 * don't want to change the subsystem state */
319 template[i
] = oldcg
->subsys
[i
];
323 /* Look through existing cgroup groups to find one to reuse */
326 list_entry(l
, struct css_set
, list
);
328 if (!memcmp(template, cg
->subsys
, sizeof(cg
->subsys
))) {
329 /* All subsystems matched */
332 /* Try the next cgroup group */
334 } while (l
!= &init_css_set
.list
);
336 /* No existing cgroup group matched */
341 * allocate_cg_links() allocates "count" cg_cgroup_link structures
342 * and chains them on tmp through their cgrp_link_list fields. Returns 0 on
343 * success or a negative error
345 static int allocate_cg_links(int count
, struct list_head
*tmp
)
347 struct cg_cgroup_link
*link
;
350 for (i
= 0; i
< count
; i
++) {
351 link
= kmalloc(sizeof(*link
), GFP_KERNEL
);
353 while (!list_empty(tmp
)) {
354 link
= list_entry(tmp
->next
,
355 struct cg_cgroup_link
,
357 list_del(&link
->cgrp_link_list
);
362 list_add(&link
->cgrp_link_list
, tmp
);
367 static void free_cg_links(struct list_head
*tmp
)
369 while (!list_empty(tmp
)) {
370 struct cg_cgroup_link
*link
;
371 link
= list_entry(tmp
->next
,
372 struct cg_cgroup_link
,
374 list_del(&link
->cgrp_link_list
);
380 * find_css_set() takes an existing cgroup group and a
381 * cgroup object, and returns a css_set object that's
382 * equivalent to the old group, but with the given cgroup
383 * substituted into the appropriate hierarchy. Must be called with
386 static struct css_set
*find_css_set(
387 struct css_set
*oldcg
, struct cgroup
*cgrp
)
390 struct cgroup_subsys_state
*template[CGROUP_SUBSYS_COUNT
];
393 struct list_head tmp_cg_links
;
394 struct cg_cgroup_link
*link
;
396 /* First see if we already have a cgroup group that matches
398 write_lock(&css_set_lock
);
399 res
= find_existing_css_set(oldcg
, cgrp
, template);
402 write_unlock(&css_set_lock
);
407 res
= kmalloc(sizeof(*res
), GFP_KERNEL
);
411 /* Allocate all the cg_cgroup_link objects that we'll need */
412 if (allocate_cg_links(root_count
, &tmp_cg_links
) < 0) {
417 kref_init(&res
->ref
);
418 INIT_LIST_HEAD(&res
->cg_links
);
419 INIT_LIST_HEAD(&res
->tasks
);
421 /* Copy the set of subsystem state objects generated in
422 * find_existing_css_set() */
423 memcpy(res
->subsys
, template, sizeof(res
->subsys
));
425 write_lock(&css_set_lock
);
426 /* Add reference counts and links from the new css_set. */
427 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
428 struct cgroup
*cgrp
= res
->subsys
[i
]->cgroup
;
429 struct cgroup_subsys
*ss
= subsys
[i
];
430 atomic_inc(&cgrp
->count
);
432 * We want to add a link once per cgroup, so we
433 * only do it for the first subsystem in each
436 if (ss
->root
->subsys_list
.next
== &ss
->sibling
) {
437 BUG_ON(list_empty(&tmp_cg_links
));
438 link
= list_entry(tmp_cg_links
.next
,
439 struct cg_cgroup_link
,
441 list_del(&link
->cgrp_link_list
);
442 list_add(&link
->cgrp_link_list
, &cgrp
->css_sets
);
444 list_add(&link
->cg_link_list
, &res
->cg_links
);
447 if (list_empty(&rootnode
.subsys_list
)) {
448 link
= list_entry(tmp_cg_links
.next
,
449 struct cg_cgroup_link
,
451 list_del(&link
->cgrp_link_list
);
452 list_add(&link
->cgrp_link_list
, &dummytop
->css_sets
);
454 list_add(&link
->cg_link_list
, &res
->cg_links
);
457 BUG_ON(!list_empty(&tmp_cg_links
));
459 /* Link this cgroup group into the list */
460 list_add(&res
->list
, &init_css_set
.list
);
462 write_unlock(&css_set_lock
);
468 * There is one global cgroup mutex. We also require taking
469 * task_lock() when dereferencing a task's cgroup subsys pointers.
470 * See "The task_lock() exception", at the end of this comment.
472 * A task must hold cgroup_mutex to modify cgroups.
474 * Any task can increment and decrement the count field without lock.
475 * So in general, code holding cgroup_mutex can't rely on the count
476 * field not changing. However, if the count goes to zero, then only
477 * cgroup_attach_task() can increment it again. Because a count of zero
478 * means that no tasks are currently attached, therefore there is no
479 * way a task attached to that cgroup can fork (the other way to
480 * increment the count). So code holding cgroup_mutex can safely
481 * assume that if the count is zero, it will stay zero. Similarly, if
482 * a task holds cgroup_mutex on a cgroup with zero count, it
483 * knows that the cgroup won't be removed, as cgroup_rmdir()
486 * The cgroup_common_file_write handler for operations that modify
487 * the cgroup hierarchy holds cgroup_mutex across the entire operation,
488 * single threading all such cgroup modifications across the system.
490 * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
491 * (usually) take cgroup_mutex. These are the two most performance
492 * critical pieces of code here. The exception occurs on cgroup_exit(),
493 * when a task in a notify_on_release cgroup exits. Then cgroup_mutex
494 * is taken, and if the cgroup count is zero, a usermode call made
495 * to the release agent with the name of the cgroup (path relative to
496 * the root of cgroup file system) as the argument.
498 * A cgroup can only be deleted if both its 'count' of using tasks
499 * is zero, and its list of 'children' cgroups is empty. Since all
500 * tasks in the system use _some_ cgroup, and since there is always at
501 * least one task in the system (init, pid == 1), therefore, top_cgroup
502 * always has either children cgroups and/or using tasks. So we don't
503 * need a special hack to ensure that top_cgroup cannot be deleted.
505 * The task_lock() exception
507 * The need for this exception arises from the action of
508 * cgroup_attach_task(), which overwrites one tasks cgroup pointer with
509 * another. It does so using cgroup_mutex, however there are
510 * several performance critical places that need to reference
511 * task->cgroup without the expense of grabbing a system global
512 * mutex. Therefore except as noted below, when dereferencing or, as
513 * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use
514 * task_lock(), which acts on a spinlock (task->alloc_lock) already in
515 * the task_struct routinely used for such matters.
517 * P.S. One more locking exception. RCU is used to guard the
518 * update of a tasks cgroup pointer by cgroup_attach_task()
522 * cgroup_lock - lock out any changes to cgroup structures
525 void cgroup_lock(void)
527 mutex_lock(&cgroup_mutex
);
531 * cgroup_unlock - release lock on cgroup changes
533 * Undo the lock taken in a previous cgroup_lock() call.
535 void cgroup_unlock(void)
537 mutex_unlock(&cgroup_mutex
);
541 * A couple of forward declarations required, due to cyclic reference loop:
542 * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
543 * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
547 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
);
548 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
);
549 static int cgroup_populate_dir(struct cgroup
*cgrp
);
550 static struct inode_operations cgroup_dir_inode_operations
;
551 static struct file_operations proc_cgroupstats_operations
;
553 static struct backing_dev_info cgroup_backing_dev_info
= {
554 .capabilities
= BDI_CAP_NO_ACCT_DIRTY
| BDI_CAP_NO_WRITEBACK
,
557 static struct inode
*cgroup_new_inode(mode_t mode
, struct super_block
*sb
)
559 struct inode
*inode
= new_inode(sb
);
562 inode
->i_mode
= mode
;
563 inode
->i_uid
= current
->fsuid
;
564 inode
->i_gid
= current
->fsgid
;
566 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
567 inode
->i_mapping
->backing_dev_info
= &cgroup_backing_dev_info
;
573 * Call subsys's pre_destroy handler.
574 * This is called before css refcnt check.
576 static void cgroup_call_pre_destroy(struct cgroup
*cgrp
)
578 struct cgroup_subsys
*ss
;
579 for_each_subsys(cgrp
->root
, ss
)
580 if (ss
->pre_destroy
&& cgrp
->subsys
[ss
->subsys_id
])
581 ss
->pre_destroy(ss
, cgrp
);
585 static void cgroup_diput(struct dentry
*dentry
, struct inode
*inode
)
587 /* is dentry a directory ? if so, kfree() associated cgroup */
588 if (S_ISDIR(inode
->i_mode
)) {
589 struct cgroup
*cgrp
= dentry
->d_fsdata
;
590 struct cgroup_subsys
*ss
;
591 BUG_ON(!(cgroup_is_removed(cgrp
)));
592 /* It's possible for external users to be holding css
593 * reference counts on a cgroup; css_put() needs to
594 * be able to access the cgroup after decrementing
595 * the reference count in order to know if it needs to
596 * queue the cgroup to be handled by the release
600 mutex_lock(&cgroup_mutex
);
602 * Release the subsystem state objects.
604 for_each_subsys(cgrp
->root
, ss
) {
605 if (cgrp
->subsys
[ss
->subsys_id
])
606 ss
->destroy(ss
, cgrp
);
609 cgrp
->root
->number_of_cgroups
--;
610 mutex_unlock(&cgroup_mutex
);
612 /* Drop the active superblock reference that we took when we
613 * created the cgroup */
614 deactivate_super(cgrp
->root
->sb
);
621 static void remove_dir(struct dentry
*d
)
623 struct dentry
*parent
= dget(d
->d_parent
);
626 simple_rmdir(parent
->d_inode
, d
);
630 static void cgroup_clear_directory(struct dentry
*dentry
)
632 struct list_head
*node
;
634 BUG_ON(!mutex_is_locked(&dentry
->d_inode
->i_mutex
));
635 spin_lock(&dcache_lock
);
636 node
= dentry
->d_subdirs
.next
;
637 while (node
!= &dentry
->d_subdirs
) {
638 struct dentry
*d
= list_entry(node
, struct dentry
, d_u
.d_child
);
641 /* This should never be called on a cgroup
642 * directory with child cgroups */
643 BUG_ON(d
->d_inode
->i_mode
& S_IFDIR
);
645 spin_unlock(&dcache_lock
);
647 simple_unlink(dentry
->d_inode
, d
);
649 spin_lock(&dcache_lock
);
651 node
= dentry
->d_subdirs
.next
;
653 spin_unlock(&dcache_lock
);
657 * NOTE : the dentry must have been dget()'ed
659 static void cgroup_d_remove_dir(struct dentry
*dentry
)
661 cgroup_clear_directory(dentry
);
663 spin_lock(&dcache_lock
);
664 list_del_init(&dentry
->d_u
.d_child
);
665 spin_unlock(&dcache_lock
);
669 static int rebind_subsystems(struct cgroupfs_root
*root
,
670 unsigned long final_bits
)
672 unsigned long added_bits
, removed_bits
;
673 struct cgroup
*cgrp
= &root
->top_cgroup
;
676 removed_bits
= root
->actual_subsys_bits
& ~final_bits
;
677 added_bits
= final_bits
& ~root
->actual_subsys_bits
;
678 /* Check that any added subsystems are currently free */
679 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
680 unsigned long bit
= 1UL << i
;
681 struct cgroup_subsys
*ss
= subsys
[i
];
682 if (!(bit
& added_bits
))
684 if (ss
->root
!= &rootnode
) {
685 /* Subsystem isn't free */
690 /* Currently we don't handle adding/removing subsystems when
691 * any child cgroups exist. This is theoretically supportable
692 * but involves complex error handling, so it's being left until
694 if (!list_empty(&cgrp
->children
))
697 /* Process each subsystem */
698 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
699 struct cgroup_subsys
*ss
= subsys
[i
];
700 unsigned long bit
= 1UL << i
;
701 if (bit
& added_bits
) {
702 /* We're binding this subsystem to this hierarchy */
703 BUG_ON(cgrp
->subsys
[i
]);
704 BUG_ON(!dummytop
->subsys
[i
]);
705 BUG_ON(dummytop
->subsys
[i
]->cgroup
!= dummytop
);
706 cgrp
->subsys
[i
] = dummytop
->subsys
[i
];
707 cgrp
->subsys
[i
]->cgroup
= cgrp
;
708 list_add(&ss
->sibling
, &root
->subsys_list
);
709 rcu_assign_pointer(ss
->root
, root
);
713 } else if (bit
& removed_bits
) {
714 /* We're removing this subsystem */
715 BUG_ON(cgrp
->subsys
[i
] != dummytop
->subsys
[i
]);
716 BUG_ON(cgrp
->subsys
[i
]->cgroup
!= cgrp
);
718 ss
->bind(ss
, dummytop
);
719 dummytop
->subsys
[i
]->cgroup
= dummytop
;
720 cgrp
->subsys
[i
] = NULL
;
721 rcu_assign_pointer(subsys
[i
]->root
, &rootnode
);
722 list_del(&ss
->sibling
);
723 } else if (bit
& final_bits
) {
724 /* Subsystem state should already exist */
725 BUG_ON(!cgrp
->subsys
[i
]);
727 /* Subsystem state shouldn't exist */
728 BUG_ON(cgrp
->subsys
[i
]);
731 root
->subsys_bits
= root
->actual_subsys_bits
= final_bits
;
737 static int cgroup_show_options(struct seq_file
*seq
, struct vfsmount
*vfs
)
739 struct cgroupfs_root
*root
= vfs
->mnt_sb
->s_fs_info
;
740 struct cgroup_subsys
*ss
;
742 mutex_lock(&cgroup_mutex
);
743 for_each_subsys(root
, ss
)
744 seq_printf(seq
, ",%s", ss
->name
);
745 if (test_bit(ROOT_NOPREFIX
, &root
->flags
))
746 seq_puts(seq
, ",noprefix");
747 if (strlen(root
->release_agent_path
))
748 seq_printf(seq
, ",release_agent=%s", root
->release_agent_path
);
749 mutex_unlock(&cgroup_mutex
);
753 struct cgroup_sb_opts
{
754 unsigned long subsys_bits
;
759 /* Convert a hierarchy specifier into a bitmask of subsystems and
761 static int parse_cgroupfs_options(char *data
,
762 struct cgroup_sb_opts
*opts
)
764 char *token
, *o
= data
?: "all";
766 opts
->subsys_bits
= 0;
768 opts
->release_agent
= NULL
;
770 while ((token
= strsep(&o
, ",")) != NULL
) {
773 if (!strcmp(token
, "all")) {
774 /* Add all non-disabled subsystems */
776 opts
->subsys_bits
= 0;
777 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
778 struct cgroup_subsys
*ss
= subsys
[i
];
780 opts
->subsys_bits
|= 1ul << i
;
782 } else if (!strcmp(token
, "noprefix")) {
783 set_bit(ROOT_NOPREFIX
, &opts
->flags
);
784 } else if (!strncmp(token
, "release_agent=", 14)) {
785 /* Specifying two release agents is forbidden */
786 if (opts
->release_agent
)
788 opts
->release_agent
= kzalloc(PATH_MAX
, GFP_KERNEL
);
789 if (!opts
->release_agent
)
791 strncpy(opts
->release_agent
, token
+ 14, PATH_MAX
- 1);
792 opts
->release_agent
[PATH_MAX
- 1] = 0;
794 struct cgroup_subsys
*ss
;
796 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
798 if (!strcmp(token
, ss
->name
)) {
800 set_bit(i
, &opts
->subsys_bits
);
804 if (i
== CGROUP_SUBSYS_COUNT
)
809 /* We can't have an empty hierarchy */
810 if (!opts
->subsys_bits
)
816 static int cgroup_remount(struct super_block
*sb
, int *flags
, char *data
)
819 struct cgroupfs_root
*root
= sb
->s_fs_info
;
820 struct cgroup
*cgrp
= &root
->top_cgroup
;
821 struct cgroup_sb_opts opts
;
823 mutex_lock(&cgrp
->dentry
->d_inode
->i_mutex
);
824 mutex_lock(&cgroup_mutex
);
826 /* See what subsystems are wanted */
827 ret
= parse_cgroupfs_options(data
, &opts
);
831 /* Don't allow flags to change at remount */
832 if (opts
.flags
!= root
->flags
) {
837 ret
= rebind_subsystems(root
, opts
.subsys_bits
);
839 /* (re)populate subsystem files */
841 cgroup_populate_dir(cgrp
);
843 if (opts
.release_agent
)
844 strcpy(root
->release_agent_path
, opts
.release_agent
);
846 if (opts
.release_agent
)
847 kfree(opts
.release_agent
);
848 mutex_unlock(&cgroup_mutex
);
849 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
853 static struct super_operations cgroup_ops
= {
854 .statfs
= simple_statfs
,
855 .drop_inode
= generic_delete_inode
,
856 .show_options
= cgroup_show_options
,
857 .remount_fs
= cgroup_remount
,
860 static void init_cgroup_root(struct cgroupfs_root
*root
)
862 struct cgroup
*cgrp
= &root
->top_cgroup
;
863 INIT_LIST_HEAD(&root
->subsys_list
);
864 INIT_LIST_HEAD(&root
->root_list
);
865 root
->number_of_cgroups
= 1;
867 cgrp
->top_cgroup
= cgrp
;
868 INIT_LIST_HEAD(&cgrp
->sibling
);
869 INIT_LIST_HEAD(&cgrp
->children
);
870 INIT_LIST_HEAD(&cgrp
->css_sets
);
871 INIT_LIST_HEAD(&cgrp
->release_list
);
874 static int cgroup_test_super(struct super_block
*sb
, void *data
)
876 struct cgroupfs_root
*new = data
;
877 struct cgroupfs_root
*root
= sb
->s_fs_info
;
879 /* First check subsystems */
880 if (new->subsys_bits
!= root
->subsys_bits
)
883 /* Next check flags */
884 if (new->flags
!= root
->flags
)
890 static int cgroup_set_super(struct super_block
*sb
, void *data
)
893 struct cgroupfs_root
*root
= data
;
895 ret
= set_anon_super(sb
, NULL
);
899 sb
->s_fs_info
= root
;
902 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
903 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
904 sb
->s_magic
= CGROUP_SUPER_MAGIC
;
905 sb
->s_op
= &cgroup_ops
;
910 static int cgroup_get_rootdir(struct super_block
*sb
)
912 struct inode
*inode
=
913 cgroup_new_inode(S_IFDIR
| S_IRUGO
| S_IXUGO
| S_IWUSR
, sb
);
914 struct dentry
*dentry
;
919 inode
->i_fop
= &simple_dir_operations
;
920 inode
->i_op
= &cgroup_dir_inode_operations
;
921 /* directories start off with i_nlink == 2 (for "." entry) */
923 dentry
= d_alloc_root(inode
);
932 static int cgroup_get_sb(struct file_system_type
*fs_type
,
933 int flags
, const char *unused_dev_name
,
934 void *data
, struct vfsmount
*mnt
)
936 struct cgroup_sb_opts opts
;
938 struct super_block
*sb
;
939 struct cgroupfs_root
*root
;
940 struct list_head tmp_cg_links
, *l
;
941 INIT_LIST_HEAD(&tmp_cg_links
);
943 /* First find the desired set of subsystems */
944 ret
= parse_cgroupfs_options(data
, &opts
);
946 if (opts
.release_agent
)
947 kfree(opts
.release_agent
);
951 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
953 if (opts
.release_agent
)
954 kfree(opts
.release_agent
);
958 init_cgroup_root(root
);
959 root
->subsys_bits
= opts
.subsys_bits
;
960 root
->flags
= opts
.flags
;
961 if (opts
.release_agent
) {
962 strcpy(root
->release_agent_path
, opts
.release_agent
);
963 kfree(opts
.release_agent
);
966 sb
= sget(fs_type
, cgroup_test_super
, cgroup_set_super
, root
);
973 if (sb
->s_fs_info
!= root
) {
974 /* Reusing an existing superblock */
975 BUG_ON(sb
->s_root
== NULL
);
980 struct cgroup
*cgrp
= &root
->top_cgroup
;
983 BUG_ON(sb
->s_root
!= NULL
);
985 ret
= cgroup_get_rootdir(sb
);
988 inode
= sb
->s_root
->d_inode
;
990 mutex_lock(&inode
->i_mutex
);
991 mutex_lock(&cgroup_mutex
);
994 * We're accessing css_set_count without locking
995 * css_set_lock here, but that's OK - it can only be
996 * increased by someone holding cgroup_lock, and
997 * that's us. The worst that can happen is that we
998 * have some link structures left over
1000 ret
= allocate_cg_links(css_set_count
, &tmp_cg_links
);
1002 mutex_unlock(&cgroup_mutex
);
1003 mutex_unlock(&inode
->i_mutex
);
1004 goto drop_new_super
;
1007 ret
= rebind_subsystems(root
, root
->subsys_bits
);
1008 if (ret
== -EBUSY
) {
1009 mutex_unlock(&cgroup_mutex
);
1010 mutex_unlock(&inode
->i_mutex
);
1011 goto drop_new_super
;
1014 /* EBUSY should be the only error here */
1017 list_add(&root
->root_list
, &roots
);
1020 sb
->s_root
->d_fsdata
= &root
->top_cgroup
;
1021 root
->top_cgroup
.dentry
= sb
->s_root
;
1023 /* Link the top cgroup in this hierarchy into all
1024 * the css_set objects */
1025 write_lock(&css_set_lock
);
1026 l
= &init_css_set
.list
;
1029 struct cg_cgroup_link
*link
;
1030 cg
= list_entry(l
, struct css_set
, list
);
1031 BUG_ON(list_empty(&tmp_cg_links
));
1032 link
= list_entry(tmp_cg_links
.next
,
1033 struct cg_cgroup_link
,
1035 list_del(&link
->cgrp_link_list
);
1037 list_add(&link
->cgrp_link_list
,
1038 &root
->top_cgroup
.css_sets
);
1039 list_add(&link
->cg_link_list
, &cg
->cg_links
);
1041 } while (l
!= &init_css_set
.list
);
1042 write_unlock(&css_set_lock
);
1044 free_cg_links(&tmp_cg_links
);
1046 BUG_ON(!list_empty(&cgrp
->sibling
));
1047 BUG_ON(!list_empty(&cgrp
->children
));
1048 BUG_ON(root
->number_of_cgroups
!= 1);
1050 cgroup_populate_dir(cgrp
);
1051 mutex_unlock(&inode
->i_mutex
);
1052 mutex_unlock(&cgroup_mutex
);
1055 return simple_set_mnt(mnt
, sb
);
1058 up_write(&sb
->s_umount
);
1059 deactivate_super(sb
);
1060 free_cg_links(&tmp_cg_links
);
1064 static void cgroup_kill_sb(struct super_block
*sb
) {
1065 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1066 struct cgroup
*cgrp
= &root
->top_cgroup
;
1071 BUG_ON(root
->number_of_cgroups
!= 1);
1072 BUG_ON(!list_empty(&cgrp
->children
));
1073 BUG_ON(!list_empty(&cgrp
->sibling
));
1075 mutex_lock(&cgroup_mutex
);
1077 /* Rebind all subsystems back to the default hierarchy */
1078 ret
= rebind_subsystems(root
, 0);
1079 /* Shouldn't be able to fail ... */
1083 * Release all the links from css_sets to this hierarchy's
1086 write_lock(&css_set_lock
);
1087 while (!list_empty(&cgrp
->css_sets
)) {
1088 struct cg_cgroup_link
*link
;
1089 link
= list_entry(cgrp
->css_sets
.next
,
1090 struct cg_cgroup_link
, cgrp_link_list
);
1091 list_del(&link
->cg_link_list
);
1092 list_del(&link
->cgrp_link_list
);
1095 write_unlock(&css_set_lock
);
1097 if (!list_empty(&root
->root_list
)) {
1098 list_del(&root
->root_list
);
1101 mutex_unlock(&cgroup_mutex
);
1104 kill_litter_super(sb
);
1107 static struct file_system_type cgroup_fs_type
= {
1109 .get_sb
= cgroup_get_sb
,
1110 .kill_sb
= cgroup_kill_sb
,
1113 static inline struct cgroup
*__d_cgrp(struct dentry
*dentry
)
1115 return dentry
->d_fsdata
;
1118 static inline struct cftype
*__d_cft(struct dentry
*dentry
)
1120 return dentry
->d_fsdata
;
1124 * cgroup_path - generate the path of a cgroup
1125 * @cgrp: the cgroup in question
1126 * @buf: the buffer to write the path into
1127 * @buflen: the length of the buffer
1129 * Called with cgroup_mutex held. Writes path of cgroup into buf.
1130 * Returns 0 on success, -errno on error.
1132 int cgroup_path(const struct cgroup
*cgrp
, char *buf
, int buflen
)
1136 if (cgrp
== dummytop
) {
1138 * Inactive subsystems have no dentry for their root
1145 start
= buf
+ buflen
;
1149 int len
= cgrp
->dentry
->d_name
.len
;
1150 if ((start
-= len
) < buf
)
1151 return -ENAMETOOLONG
;
1152 memcpy(start
, cgrp
->dentry
->d_name
.name
, len
);
1153 cgrp
= cgrp
->parent
;
1159 return -ENAMETOOLONG
;
1162 memmove(buf
, start
, buf
+ buflen
- start
);
1167 * Return the first subsystem attached to a cgroup's hierarchy, and
1171 static void get_first_subsys(const struct cgroup
*cgrp
,
1172 struct cgroup_subsys_state
**css
, int *subsys_id
)
1174 const struct cgroupfs_root
*root
= cgrp
->root
;
1175 const struct cgroup_subsys
*test_ss
;
1176 BUG_ON(list_empty(&root
->subsys_list
));
1177 test_ss
= list_entry(root
->subsys_list
.next
,
1178 struct cgroup_subsys
, sibling
);
1180 *css
= cgrp
->subsys
[test_ss
->subsys_id
];
1184 *subsys_id
= test_ss
->subsys_id
;
1188 * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp'
1189 * @cgrp: the cgroup the task is attaching to
1190 * @tsk: the task to be attached
1192 * Call holding cgroup_mutex. May take task_lock of
1193 * the task 'tsk' during call.
1195 int cgroup_attach_task(struct cgroup
*cgrp
, struct task_struct
*tsk
)
1198 struct cgroup_subsys
*ss
;
1199 struct cgroup
*oldcgrp
;
1200 struct css_set
*cg
= tsk
->cgroups
;
1201 struct css_set
*newcg
;
1202 struct cgroupfs_root
*root
= cgrp
->root
;
1205 get_first_subsys(cgrp
, NULL
, &subsys_id
);
1207 /* Nothing to do if the task is already in that cgroup */
1208 oldcgrp
= task_cgroup(tsk
, subsys_id
);
1209 if (cgrp
== oldcgrp
)
1212 for_each_subsys(root
, ss
) {
1213 if (ss
->can_attach
) {
1214 retval
= ss
->can_attach(ss
, cgrp
, tsk
);
1221 * Locate or allocate a new css_set for this task,
1222 * based on its final set of cgroups
1224 newcg
= find_css_set(cg
, cgrp
);
1229 if (tsk
->flags
& PF_EXITING
) {
1234 rcu_assign_pointer(tsk
->cgroups
, newcg
);
1237 /* Update the css_set linked lists if we're using them */
1238 write_lock(&css_set_lock
);
1239 if (!list_empty(&tsk
->cg_list
)) {
1240 list_del(&tsk
->cg_list
);
1241 list_add(&tsk
->cg_list
, &newcg
->tasks
);
1243 write_unlock(&css_set_lock
);
1245 for_each_subsys(root
, ss
) {
1247 ss
->attach(ss
, cgrp
, oldcgrp
, tsk
);
1249 set_bit(CGRP_RELEASABLE
, &oldcgrp
->flags
);
1256 * Attach task with pid 'pid' to cgroup 'cgrp'. Call with
1257 * cgroup_mutex, may take task_lock of task
1259 static int attach_task_by_pid(struct cgroup
*cgrp
, char *pidbuf
)
1262 struct task_struct
*tsk
;
1265 if (sscanf(pidbuf
, "%d", &pid
) != 1)
1270 tsk
= find_task_by_vpid(pid
);
1271 if (!tsk
|| tsk
->flags
& PF_EXITING
) {
1275 get_task_struct(tsk
);
1278 if ((current
->euid
) && (current
->euid
!= tsk
->uid
)
1279 && (current
->euid
!= tsk
->suid
)) {
1280 put_task_struct(tsk
);
1285 get_task_struct(tsk
);
1288 ret
= cgroup_attach_task(cgrp
, tsk
);
1289 put_task_struct(tsk
);
1293 /* The various types of files and directories in a cgroup file system */
1294 enum cgroup_filetype
{
1298 FILE_NOTIFY_ON_RELEASE
,
1302 static ssize_t
cgroup_write_X64(struct cgroup
*cgrp
, struct cftype
*cft
,
1304 const char __user
*userbuf
,
1305 size_t nbytes
, loff_t
*unused_ppos
)
1313 if (nbytes
>= sizeof(buffer
))
1315 if (copy_from_user(buffer
, userbuf
, nbytes
))
1318 buffer
[nbytes
] = 0; /* nul-terminate */
1320 if (cft
->write_u64
) {
1321 u64 val
= simple_strtoull(buffer
, &end
, 0);
1324 retval
= cft
->write_u64(cgrp
, cft
, val
);
1326 s64 val
= simple_strtoll(buffer
, &end
, 0);
1329 retval
= cft
->write_s64(cgrp
, cft
, val
);
1336 static ssize_t
cgroup_common_file_write(struct cgroup
*cgrp
,
1339 const char __user
*userbuf
,
1340 size_t nbytes
, loff_t
*unused_ppos
)
1342 enum cgroup_filetype type
= cft
->private;
1346 if (nbytes
>= PATH_MAX
)
1349 /* +1 for nul-terminator */
1350 buffer
= kmalloc(nbytes
+ 1, GFP_KERNEL
);
1354 if (copy_from_user(buffer
, userbuf
, nbytes
)) {
1358 buffer
[nbytes
] = 0; /* nul-terminate */
1359 strstrip(buffer
); /* strip -just- trailing whitespace */
1361 mutex_lock(&cgroup_mutex
);
1364 * This was already checked for in cgroup_file_write(), but
1365 * check again now we're holding cgroup_mutex.
1367 if (cgroup_is_removed(cgrp
)) {
1374 retval
= attach_task_by_pid(cgrp
, buffer
);
1376 case FILE_NOTIFY_ON_RELEASE
:
1377 clear_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
1378 if (simple_strtoul(buffer
, NULL
, 10) != 0)
1379 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
1381 clear_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
1383 case FILE_RELEASE_AGENT
:
1384 BUILD_BUG_ON(sizeof(cgrp
->root
->release_agent_path
) < PATH_MAX
);
1385 strcpy(cgrp
->root
->release_agent_path
, buffer
);
1395 mutex_unlock(&cgroup_mutex
);
1401 static ssize_t
cgroup_file_write(struct file
*file
, const char __user
*buf
,
1402 size_t nbytes
, loff_t
*ppos
)
1404 struct cftype
*cft
= __d_cft(file
->f_dentry
);
1405 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
1407 if (!cft
|| cgroup_is_removed(cgrp
))
1410 return cft
->write(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1411 if (cft
->write_u64
|| cft
->write_s64
)
1412 return cgroup_write_X64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1414 int ret
= cft
->trigger(cgrp
, (unsigned int)cft
->private);
1415 return ret
? ret
: nbytes
;
1420 static ssize_t
cgroup_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
,
1422 char __user
*buf
, size_t nbytes
,
1426 u64 val
= cft
->read_u64(cgrp
, cft
);
1427 int len
= sprintf(tmp
, "%llu\n", (unsigned long long) val
);
1429 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
1432 static ssize_t
cgroup_read_s64(struct cgroup
*cgrp
, struct cftype
*cft
,
1434 char __user
*buf
, size_t nbytes
,
1438 s64 val
= cft
->read_s64(cgrp
, cft
);
1439 int len
= sprintf(tmp
, "%lld\n", (long long) val
);
1441 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
1444 static ssize_t
cgroup_common_file_read(struct cgroup
*cgrp
,
1448 size_t nbytes
, loff_t
*ppos
)
1450 enum cgroup_filetype type
= cft
->private;
1455 if (!(page
= (char *)__get_free_page(GFP_KERNEL
)))
1461 case FILE_RELEASE_AGENT
:
1463 struct cgroupfs_root
*root
;
1465 mutex_lock(&cgroup_mutex
);
1467 n
= strnlen(root
->release_agent_path
,
1468 sizeof(root
->release_agent_path
));
1469 n
= min(n
, (size_t) PAGE_SIZE
);
1470 strncpy(s
, root
->release_agent_path
, n
);
1471 mutex_unlock(&cgroup_mutex
);
1481 retval
= simple_read_from_buffer(buf
, nbytes
, ppos
, page
, s
- page
);
1483 free_page((unsigned long)page
);
1487 static ssize_t
cgroup_file_read(struct file
*file
, char __user
*buf
,
1488 size_t nbytes
, loff_t
*ppos
)
1490 struct cftype
*cft
= __d_cft(file
->f_dentry
);
1491 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
1493 if (!cft
|| cgroup_is_removed(cgrp
))
1497 return cft
->read(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1499 return cgroup_read_u64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1501 return cgroup_read_s64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1506 * seqfile ops/methods for returning structured data. Currently just
1507 * supports string->u64 maps, but can be extended in future.
1510 struct cgroup_seqfile_state
{
1512 struct cgroup
*cgroup
;
1515 static int cgroup_map_add(struct cgroup_map_cb
*cb
, const char *key
, u64 value
)
1517 struct seq_file
*sf
= cb
->state
;
1518 return seq_printf(sf
, "%s %llu\n", key
, (unsigned long long)value
);
1521 static int cgroup_seqfile_show(struct seq_file
*m
, void *arg
)
1523 struct cgroup_seqfile_state
*state
= m
->private;
1524 struct cftype
*cft
= state
->cft
;
1525 struct cgroup_map_cb cb
= {
1526 .fill
= cgroup_map_add
,
1529 return cft
->read_map(state
->cgroup
, cft
, &cb
);
1532 int cgroup_seqfile_release(struct inode
*inode
, struct file
*file
)
1534 struct seq_file
*seq
= file
->private_data
;
1535 kfree(seq
->private);
1536 return single_release(inode
, file
);
1539 static struct file_operations cgroup_seqfile_operations
= {
1541 .llseek
= seq_lseek
,
1542 .release
= cgroup_seqfile_release
,
1545 static int cgroup_file_open(struct inode
*inode
, struct file
*file
)
1550 err
= generic_file_open(inode
, file
);
1554 cft
= __d_cft(file
->f_dentry
);
1557 if (cft
->read_map
) {
1558 struct cgroup_seqfile_state
*state
=
1559 kzalloc(sizeof(*state
), GFP_USER
);
1563 state
->cgroup
= __d_cgrp(file
->f_dentry
->d_parent
);
1564 file
->f_op
= &cgroup_seqfile_operations
;
1565 err
= single_open(file
, cgroup_seqfile_show
, state
);
1568 } else if (cft
->open
)
1569 err
= cft
->open(inode
, file
);
1576 static int cgroup_file_release(struct inode
*inode
, struct file
*file
)
1578 struct cftype
*cft
= __d_cft(file
->f_dentry
);
1580 return cft
->release(inode
, file
);
1585 * cgroup_rename - Only allow simple rename of directories in place.
1587 static int cgroup_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
1588 struct inode
*new_dir
, struct dentry
*new_dentry
)
1590 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
))
1592 if (new_dentry
->d_inode
)
1594 if (old_dir
!= new_dir
)
1596 return simple_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
1599 static struct file_operations cgroup_file_operations
= {
1600 .read
= cgroup_file_read
,
1601 .write
= cgroup_file_write
,
1602 .llseek
= generic_file_llseek
,
1603 .open
= cgroup_file_open
,
1604 .release
= cgroup_file_release
,
1607 static struct inode_operations cgroup_dir_inode_operations
= {
1608 .lookup
= simple_lookup
,
1609 .mkdir
= cgroup_mkdir
,
1610 .rmdir
= cgroup_rmdir
,
1611 .rename
= cgroup_rename
,
1614 static int cgroup_create_file(struct dentry
*dentry
, int mode
,
1615 struct super_block
*sb
)
1617 static struct dentry_operations cgroup_dops
= {
1618 .d_iput
= cgroup_diput
,
1621 struct inode
*inode
;
1625 if (dentry
->d_inode
)
1628 inode
= cgroup_new_inode(mode
, sb
);
1632 if (S_ISDIR(mode
)) {
1633 inode
->i_op
= &cgroup_dir_inode_operations
;
1634 inode
->i_fop
= &simple_dir_operations
;
1636 /* start off with i_nlink == 2 (for "." entry) */
1639 /* start with the directory inode held, so that we can
1640 * populate it without racing with another mkdir */
1641 mutex_lock_nested(&inode
->i_mutex
, I_MUTEX_CHILD
);
1642 } else if (S_ISREG(mode
)) {
1644 inode
->i_fop
= &cgroup_file_operations
;
1646 dentry
->d_op
= &cgroup_dops
;
1647 d_instantiate(dentry
, inode
);
1648 dget(dentry
); /* Extra count - pin the dentry in core */
1653 * cgroup_create_dir - create a directory for an object.
1654 * @cgrp: the cgroup we create the directory for. It must have a valid
1655 * ->parent field. And we are going to fill its ->dentry field.
1656 * @dentry: dentry of the new cgroup
1657 * @mode: mode to set on new directory.
1659 static int cgroup_create_dir(struct cgroup
*cgrp
, struct dentry
*dentry
,
1662 struct dentry
*parent
;
1665 parent
= cgrp
->parent
->dentry
;
1666 error
= cgroup_create_file(dentry
, S_IFDIR
| mode
, cgrp
->root
->sb
);
1668 dentry
->d_fsdata
= cgrp
;
1669 inc_nlink(parent
->d_inode
);
1670 cgrp
->dentry
= dentry
;
1678 int cgroup_add_file(struct cgroup
*cgrp
,
1679 struct cgroup_subsys
*subsys
,
1680 const struct cftype
*cft
)
1682 struct dentry
*dir
= cgrp
->dentry
;
1683 struct dentry
*dentry
;
1686 char name
[MAX_CGROUP_TYPE_NAMELEN
+ MAX_CFTYPE_NAME
+ 2] = { 0 };
1687 if (subsys
&& !test_bit(ROOT_NOPREFIX
, &cgrp
->root
->flags
)) {
1688 strcpy(name
, subsys
->name
);
1691 strcat(name
, cft
->name
);
1692 BUG_ON(!mutex_is_locked(&dir
->d_inode
->i_mutex
));
1693 dentry
= lookup_one_len(name
, dir
, strlen(name
));
1694 if (!IS_ERR(dentry
)) {
1695 error
= cgroup_create_file(dentry
, 0644 | S_IFREG
,
1698 dentry
->d_fsdata
= (void *)cft
;
1701 error
= PTR_ERR(dentry
);
1705 int cgroup_add_files(struct cgroup
*cgrp
,
1706 struct cgroup_subsys
*subsys
,
1707 const struct cftype cft
[],
1711 for (i
= 0; i
< count
; i
++) {
1712 err
= cgroup_add_file(cgrp
, subsys
, &cft
[i
]);
1720 * cgroup_task_count - count the number of tasks in a cgroup.
1721 * @cgrp: the cgroup in question
1723 * Return the number of tasks in the cgroup.
1725 int cgroup_task_count(const struct cgroup
*cgrp
)
1728 struct list_head
*l
;
1730 read_lock(&css_set_lock
);
1731 l
= cgrp
->css_sets
.next
;
1732 while (l
!= &cgrp
->css_sets
) {
1733 struct cg_cgroup_link
*link
=
1734 list_entry(l
, struct cg_cgroup_link
, cgrp_link_list
);
1735 count
+= atomic_read(&link
->cg
->ref
.refcount
);
1738 read_unlock(&css_set_lock
);
1743 * Advance a list_head iterator. The iterator should be positioned at
1744 * the start of a css_set
1746 static void cgroup_advance_iter(struct cgroup
*cgrp
,
1747 struct cgroup_iter
*it
)
1749 struct list_head
*l
= it
->cg_link
;
1750 struct cg_cgroup_link
*link
;
1753 /* Advance to the next non-empty css_set */
1756 if (l
== &cgrp
->css_sets
) {
1760 link
= list_entry(l
, struct cg_cgroup_link
, cgrp_link_list
);
1762 } while (list_empty(&cg
->tasks
));
1764 it
->task
= cg
->tasks
.next
;
1768 * To reduce the fork() overhead for systems that are not actually
1769 * using their cgroups capability, we don't maintain the lists running
1770 * through each css_set to its tasks until we see the list actually
1771 * used - in other words after the first call to cgroup_iter_start().
1773 * The tasklist_lock is not held here, as do_each_thread() and
1774 * while_each_thread() are protected by RCU.
1776 static void cgroup_enable_task_cg_lists(void)
1778 struct task_struct
*p
, *g
;
1779 write_lock(&css_set_lock
);
1780 use_task_css_set_links
= 1;
1781 do_each_thread(g
, p
) {
1784 * We should check if the process is exiting, otherwise
1785 * it will race with cgroup_exit() in that the list
1786 * entry won't be deleted though the process has exited.
1788 if (!(p
->flags
& PF_EXITING
) && list_empty(&p
->cg_list
))
1789 list_add(&p
->cg_list
, &p
->cgroups
->tasks
);
1791 } while_each_thread(g
, p
);
1792 write_unlock(&css_set_lock
);
1795 void cgroup_iter_start(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
1798 * The first time anyone tries to iterate across a cgroup,
1799 * we need to enable the list linking each css_set to its
1800 * tasks, and fix up all existing tasks.
1802 if (!use_task_css_set_links
)
1803 cgroup_enable_task_cg_lists();
1805 read_lock(&css_set_lock
);
1806 it
->cg_link
= &cgrp
->css_sets
;
1807 cgroup_advance_iter(cgrp
, it
);
1810 struct task_struct
*cgroup_iter_next(struct cgroup
*cgrp
,
1811 struct cgroup_iter
*it
)
1813 struct task_struct
*res
;
1814 struct list_head
*l
= it
->task
;
1816 /* If the iterator cg is NULL, we have no tasks */
1819 res
= list_entry(l
, struct task_struct
, cg_list
);
1820 /* Advance iterator to find next entry */
1822 if (l
== &res
->cgroups
->tasks
) {
1823 /* We reached the end of this task list - move on to
1824 * the next cg_cgroup_link */
1825 cgroup_advance_iter(cgrp
, it
);
1832 void cgroup_iter_end(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
1834 read_unlock(&css_set_lock
);
1837 static inline int started_after_time(struct task_struct
*t1
,
1838 struct timespec
*time
,
1839 struct task_struct
*t2
)
1841 int start_diff
= timespec_compare(&t1
->start_time
, time
);
1842 if (start_diff
> 0) {
1844 } else if (start_diff
< 0) {
1848 * Arbitrarily, if two processes started at the same
1849 * time, we'll say that the lower pointer value
1850 * started first. Note that t2 may have exited by now
1851 * so this may not be a valid pointer any longer, but
1852 * that's fine - it still serves to distinguish
1853 * between two tasks started (effectively) simultaneously.
1860 * This function is a callback from heap_insert() and is used to order
1862 * In this case we order the heap in descending task start time.
1864 static inline int started_after(void *p1
, void *p2
)
1866 struct task_struct
*t1
= p1
;
1867 struct task_struct
*t2
= p2
;
1868 return started_after_time(t1
, &t2
->start_time
, t2
);
1872 * cgroup_scan_tasks - iterate though all the tasks in a cgroup
1873 * @scan: struct cgroup_scanner containing arguments for the scan
1875 * Arguments include pointers to callback functions test_task() and
1877 * Iterate through all the tasks in a cgroup, calling test_task() for each,
1878 * and if it returns true, call process_task() for it also.
1879 * The test_task pointer may be NULL, meaning always true (select all tasks).
1880 * Effectively duplicates cgroup_iter_{start,next,end}()
1881 * but does not lock css_set_lock for the call to process_task().
1882 * The struct cgroup_scanner may be embedded in any structure of the caller's
1884 * It is guaranteed that process_task() will act on every task that
1885 * is a member of the cgroup for the duration of this call. This
1886 * function may or may not call process_task() for tasks that exit
1887 * or move to a different cgroup during the call, or are forked or
1888 * move into the cgroup during the call.
1890 * Note that test_task() may be called with locks held, and may in some
1891 * situations be called multiple times for the same task, so it should
1893 * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been
1894 * pre-allocated and will be used for heap operations (and its "gt" member will
1895 * be overwritten), else a temporary heap will be used (allocation of which
1896 * may cause this function to fail).
1898 int cgroup_scan_tasks(struct cgroup_scanner
*scan
)
1901 struct cgroup_iter it
;
1902 struct task_struct
*p
, *dropped
;
1903 /* Never dereference latest_task, since it's not refcounted */
1904 struct task_struct
*latest_task
= NULL
;
1905 struct ptr_heap tmp_heap
;
1906 struct ptr_heap
*heap
;
1907 struct timespec latest_time
= { 0, 0 };
1910 /* The caller supplied our heap and pre-allocated its memory */
1912 heap
->gt
= &started_after
;
1914 /* We need to allocate our own heap memory */
1916 retval
= heap_init(heap
, PAGE_SIZE
, GFP_KERNEL
, &started_after
);
1918 /* cannot allocate the heap */
1924 * Scan tasks in the cgroup, using the scanner's "test_task" callback
1925 * to determine which are of interest, and using the scanner's
1926 * "process_task" callback to process any of them that need an update.
1927 * Since we don't want to hold any locks during the task updates,
1928 * gather tasks to be processed in a heap structure.
1929 * The heap is sorted by descending task start time.
1930 * If the statically-sized heap fills up, we overflow tasks that
1931 * started later, and in future iterations only consider tasks that
1932 * started after the latest task in the previous pass. This
1933 * guarantees forward progress and that we don't miss any tasks.
1936 cgroup_iter_start(scan
->cg
, &it
);
1937 while ((p
= cgroup_iter_next(scan
->cg
, &it
))) {
1939 * Only affect tasks that qualify per the caller's callback,
1940 * if he provided one
1942 if (scan
->test_task
&& !scan
->test_task(p
, scan
))
1945 * Only process tasks that started after the last task
1948 if (!started_after_time(p
, &latest_time
, latest_task
))
1950 dropped
= heap_insert(heap
, p
);
1951 if (dropped
== NULL
) {
1953 * The new task was inserted; the heap wasn't
1957 } else if (dropped
!= p
) {
1959 * The new task was inserted, and pushed out a
1963 put_task_struct(dropped
);
1966 * Else the new task was newer than anything already in
1967 * the heap and wasn't inserted
1970 cgroup_iter_end(scan
->cg
, &it
);
1973 for (i
= 0; i
< heap
->size
; i
++) {
1974 struct task_struct
*q
= heap
->ptrs
[i
];
1976 latest_time
= q
->start_time
;
1979 /* Process the task per the caller's callback */
1980 scan
->process_task(q
, scan
);
1984 * If we had to process any tasks at all, scan again
1985 * in case some of them were in the middle of forking
1986 * children that didn't get processed.
1987 * Not the most efficient way to do it, but it avoids
1988 * having to take callback_mutex in the fork path
1992 if (heap
== &tmp_heap
)
1993 heap_free(&tmp_heap
);
1998 * Stuff for reading the 'tasks' file.
2000 * Reading this file can return large amounts of data if a cgroup has
2001 * *lots* of attached tasks. So it may need several calls to read(),
2002 * but we cannot guarantee that the information we produce is correct
2003 * unless we produce it entirely atomically.
2005 * Upon tasks file open(), a struct ctr_struct is allocated, that
2006 * will have a pointer to an array (also allocated here). The struct
2007 * ctr_struct * is stored in file->private_data. Its resources will
2008 * be freed by release() when the file is closed. The array is used
2009 * to sprintf the PIDs and then used by read().
2017 * Load into 'pidarray' up to 'npids' of the tasks using cgroup
2018 * 'cgrp'. Return actual number of pids loaded. No need to
2019 * task_lock(p) when reading out p->cgroup, since we're in an RCU
2020 * read section, so the css_set can't go away, and is
2021 * immutable after creation.
2023 static int pid_array_load(pid_t
*pidarray
, int npids
, struct cgroup
*cgrp
)
2026 struct cgroup_iter it
;
2027 struct task_struct
*tsk
;
2028 cgroup_iter_start(cgrp
, &it
);
2029 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
2030 if (unlikely(n
== npids
))
2032 pidarray
[n
++] = task_pid_vnr(tsk
);
2034 cgroup_iter_end(cgrp
, &it
);
2039 * cgroupstats_build - build and fill cgroupstats
2040 * @stats: cgroupstats to fill information into
2041 * @dentry: A dentry entry belonging to the cgroup for which stats have
2044 * Build and fill cgroupstats so that taskstats can export it to user
2047 int cgroupstats_build(struct cgroupstats
*stats
, struct dentry
*dentry
)
2050 struct cgroup
*cgrp
;
2051 struct cgroup_iter it
;
2052 struct task_struct
*tsk
;
2054 * Validate dentry by checking the superblock operations
2056 if (dentry
->d_sb
->s_op
!= &cgroup_ops
)
2060 cgrp
= dentry
->d_fsdata
;
2063 cgroup_iter_start(cgrp
, &it
);
2064 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
2065 switch (tsk
->state
) {
2067 stats
->nr_running
++;
2069 case TASK_INTERRUPTIBLE
:
2070 stats
->nr_sleeping
++;
2072 case TASK_UNINTERRUPTIBLE
:
2073 stats
->nr_uninterruptible
++;
2076 stats
->nr_stopped
++;
2079 if (delayacct_is_task_waiting_on_io(tsk
))
2080 stats
->nr_io_wait
++;
2084 cgroup_iter_end(cgrp
, &it
);
2091 static int cmppid(const void *a
, const void *b
)
2093 return *(pid_t
*)a
- *(pid_t
*)b
;
2097 * Convert array 'a' of 'npids' pid_t's to a string of newline separated
2098 * decimal pids in 'buf'. Don't write more than 'sz' chars, but return
2099 * count 'cnt' of how many chars would be written if buf were large enough.
2101 static int pid_array_to_buf(char *buf
, int sz
, pid_t
*a
, int npids
)
2106 for (i
= 0; i
< npids
; i
++)
2107 cnt
+= snprintf(buf
+ cnt
, max(sz
- cnt
, 0), "%d\n", a
[i
]);
2112 * Handle an open on 'tasks' file. Prepare a buffer listing the
2113 * process id's of tasks currently attached to the cgroup being opened.
2115 * Does not require any specific cgroup mutexes, and does not take any.
2117 static int cgroup_tasks_open(struct inode
*unused
, struct file
*file
)
2119 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
2120 struct ctr_struct
*ctr
;
2125 if (!(file
->f_mode
& FMODE_READ
))
2128 ctr
= kmalloc(sizeof(*ctr
), GFP_KERNEL
);
2133 * If cgroup gets more users after we read count, we won't have
2134 * enough space - tough. This race is indistinguishable to the
2135 * caller from the case that the additional cgroup users didn't
2136 * show up until sometime later on.
2138 npids
= cgroup_task_count(cgrp
);
2140 pidarray
= kmalloc(npids
* sizeof(pid_t
), GFP_KERNEL
);
2144 npids
= pid_array_load(pidarray
, npids
, cgrp
);
2145 sort(pidarray
, npids
, sizeof(pid_t
), cmppid
, NULL
);
2147 /* Call pid_array_to_buf() twice, first just to get bufsz */
2148 ctr
->bufsz
= pid_array_to_buf(&c
, sizeof(c
), pidarray
, npids
) + 1;
2149 ctr
->buf
= kmalloc(ctr
->bufsz
, GFP_KERNEL
);
2152 ctr
->bufsz
= pid_array_to_buf(ctr
->buf
, ctr
->bufsz
, pidarray
, npids
);
2159 file
->private_data
= ctr
;
2170 static ssize_t
cgroup_tasks_read(struct cgroup
*cgrp
,
2172 struct file
*file
, char __user
*buf
,
2173 size_t nbytes
, loff_t
*ppos
)
2175 struct ctr_struct
*ctr
= file
->private_data
;
2177 return simple_read_from_buffer(buf
, nbytes
, ppos
, ctr
->buf
, ctr
->bufsz
);
2180 static int cgroup_tasks_release(struct inode
*unused_inode
,
2183 struct ctr_struct
*ctr
;
2185 if (file
->f_mode
& FMODE_READ
) {
2186 ctr
= file
->private_data
;
2193 static u64
cgroup_read_notify_on_release(struct cgroup
*cgrp
,
2196 return notify_on_release(cgrp
);
2200 * for the common functions, 'private' gives the type of file
2202 static struct cftype files
[] = {
2205 .open
= cgroup_tasks_open
,
2206 .read
= cgroup_tasks_read
,
2207 .write
= cgroup_common_file_write
,
2208 .release
= cgroup_tasks_release
,
2209 .private = FILE_TASKLIST
,
2213 .name
= "notify_on_release",
2214 .read_u64
= cgroup_read_notify_on_release
,
2215 .write
= cgroup_common_file_write
,
2216 .private = FILE_NOTIFY_ON_RELEASE
,
2220 static struct cftype cft_release_agent
= {
2221 .name
= "release_agent",
2222 .read
= cgroup_common_file_read
,
2223 .write
= cgroup_common_file_write
,
2224 .private = FILE_RELEASE_AGENT
,
2227 static int cgroup_populate_dir(struct cgroup
*cgrp
)
2230 struct cgroup_subsys
*ss
;
2232 /* First clear out any existing files */
2233 cgroup_clear_directory(cgrp
->dentry
);
2235 err
= cgroup_add_files(cgrp
, NULL
, files
, ARRAY_SIZE(files
));
2239 if (cgrp
== cgrp
->top_cgroup
) {
2240 if ((err
= cgroup_add_file(cgrp
, NULL
, &cft_release_agent
)) < 0)
2244 for_each_subsys(cgrp
->root
, ss
) {
2245 if (ss
->populate
&& (err
= ss
->populate(ss
, cgrp
)) < 0)
2252 static void init_cgroup_css(struct cgroup_subsys_state
*css
,
2253 struct cgroup_subsys
*ss
,
2254 struct cgroup
*cgrp
)
2257 atomic_set(&css
->refcnt
, 0);
2259 if (cgrp
== dummytop
)
2260 set_bit(CSS_ROOT
, &css
->flags
);
2261 BUG_ON(cgrp
->subsys
[ss
->subsys_id
]);
2262 cgrp
->subsys
[ss
->subsys_id
] = css
;
2266 * cgroup_create - create a cgroup
2267 * @parent: cgroup that will be parent of the new cgroup
2268 * @dentry: dentry of the new cgroup
2269 * @mode: mode to set on new inode
2271 * Must be called with the mutex on the parent inode held
2273 static long cgroup_create(struct cgroup
*parent
, struct dentry
*dentry
,
2276 struct cgroup
*cgrp
;
2277 struct cgroupfs_root
*root
= parent
->root
;
2279 struct cgroup_subsys
*ss
;
2280 struct super_block
*sb
= root
->sb
;
2282 cgrp
= kzalloc(sizeof(*cgrp
), GFP_KERNEL
);
2286 /* Grab a reference on the superblock so the hierarchy doesn't
2287 * get deleted on unmount if there are child cgroups. This
2288 * can be done outside cgroup_mutex, since the sb can't
2289 * disappear while someone has an open control file on the
2291 atomic_inc(&sb
->s_active
);
2293 mutex_lock(&cgroup_mutex
);
2295 INIT_LIST_HEAD(&cgrp
->sibling
);
2296 INIT_LIST_HEAD(&cgrp
->children
);
2297 INIT_LIST_HEAD(&cgrp
->css_sets
);
2298 INIT_LIST_HEAD(&cgrp
->release_list
);
2300 cgrp
->parent
= parent
;
2301 cgrp
->root
= parent
->root
;
2302 cgrp
->top_cgroup
= parent
->top_cgroup
;
2304 if (notify_on_release(parent
))
2305 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
2307 for_each_subsys(root
, ss
) {
2308 struct cgroup_subsys_state
*css
= ss
->create(ss
, cgrp
);
2313 init_cgroup_css(css
, ss
, cgrp
);
2316 list_add(&cgrp
->sibling
, &cgrp
->parent
->children
);
2317 root
->number_of_cgroups
++;
2319 err
= cgroup_create_dir(cgrp
, dentry
, mode
);
2323 /* The cgroup directory was pre-locked for us */
2324 BUG_ON(!mutex_is_locked(&cgrp
->dentry
->d_inode
->i_mutex
));
2326 err
= cgroup_populate_dir(cgrp
);
2327 /* If err < 0, we have a half-filled directory - oh well ;) */
2329 mutex_unlock(&cgroup_mutex
);
2330 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
2336 list_del(&cgrp
->sibling
);
2337 root
->number_of_cgroups
--;
2341 for_each_subsys(root
, ss
) {
2342 if (cgrp
->subsys
[ss
->subsys_id
])
2343 ss
->destroy(ss
, cgrp
);
2346 mutex_unlock(&cgroup_mutex
);
2348 /* Release the reference count that we took on the superblock */
2349 deactivate_super(sb
);
2355 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
2357 struct cgroup
*c_parent
= dentry
->d_parent
->d_fsdata
;
2359 /* the vfs holds inode->i_mutex already */
2360 return cgroup_create(c_parent
, dentry
, mode
| S_IFDIR
);
2363 static inline int cgroup_has_css_refs(struct cgroup
*cgrp
)
2365 /* Check the reference count on each subsystem. Since we
2366 * already established that there are no tasks in the
2367 * cgroup, if the css refcount is also 0, then there should
2368 * be no outstanding references, so the subsystem is safe to
2369 * destroy. We scan across all subsystems rather than using
2370 * the per-hierarchy linked list of mounted subsystems since
2371 * we can be called via check_for_release() with no
2372 * synchronization other than RCU, and the subsystem linked
2373 * list isn't RCU-safe */
2375 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2376 struct cgroup_subsys
*ss
= subsys
[i
];
2377 struct cgroup_subsys_state
*css
;
2378 /* Skip subsystems not in this hierarchy */
2379 if (ss
->root
!= cgrp
->root
)
2381 css
= cgrp
->subsys
[ss
->subsys_id
];
2382 /* When called from check_for_release() it's possible
2383 * that by this point the cgroup has been removed
2384 * and the css deleted. But a false-positive doesn't
2385 * matter, since it can only happen if the cgroup
2386 * has been deleted and hence no longer needs the
2387 * release agent to be called anyway. */
2388 if (css
&& atomic_read(&css
->refcnt
))
2394 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
)
2396 struct cgroup
*cgrp
= dentry
->d_fsdata
;
2398 struct cgroup
*parent
;
2399 struct super_block
*sb
;
2400 struct cgroupfs_root
*root
;
2402 /* the vfs holds both inode->i_mutex already */
2404 mutex_lock(&cgroup_mutex
);
2405 if (atomic_read(&cgrp
->count
) != 0) {
2406 mutex_unlock(&cgroup_mutex
);
2409 if (!list_empty(&cgrp
->children
)) {
2410 mutex_unlock(&cgroup_mutex
);
2414 parent
= cgrp
->parent
;
2419 * Call pre_destroy handlers of subsys. Notify subsystems
2420 * that rmdir() request comes.
2422 cgroup_call_pre_destroy(cgrp
);
2424 if (cgroup_has_css_refs(cgrp
)) {
2425 mutex_unlock(&cgroup_mutex
);
2429 spin_lock(&release_list_lock
);
2430 set_bit(CGRP_REMOVED
, &cgrp
->flags
);
2431 if (!list_empty(&cgrp
->release_list
))
2432 list_del(&cgrp
->release_list
);
2433 spin_unlock(&release_list_lock
);
2434 /* delete my sibling from parent->children */
2435 list_del(&cgrp
->sibling
);
2436 spin_lock(&cgrp
->dentry
->d_lock
);
2437 d
= dget(cgrp
->dentry
);
2438 cgrp
->dentry
= NULL
;
2439 spin_unlock(&d
->d_lock
);
2441 cgroup_d_remove_dir(d
);
2444 set_bit(CGRP_RELEASABLE
, &parent
->flags
);
2445 check_for_release(parent
);
2447 mutex_unlock(&cgroup_mutex
);
2451 static void __init
cgroup_init_subsys(struct cgroup_subsys
*ss
)
2453 struct cgroup_subsys_state
*css
;
2454 struct list_head
*l
;
2456 printk(KERN_INFO
"Initializing cgroup subsys %s\n", ss
->name
);
2458 /* Create the top cgroup state for this subsystem */
2459 ss
->root
= &rootnode
;
2460 css
= ss
->create(ss
, dummytop
);
2461 /* We don't handle early failures gracefully */
2462 BUG_ON(IS_ERR(css
));
2463 init_cgroup_css(css
, ss
, dummytop
);
2465 /* Update all cgroup groups to contain a subsys
2466 * pointer to this state - since the subsystem is
2467 * newly registered, all tasks and hence all cgroup
2468 * groups are in the subsystem's top cgroup. */
2469 write_lock(&css_set_lock
);
2470 l
= &init_css_set
.list
;
2472 struct css_set
*cg
=
2473 list_entry(l
, struct css_set
, list
);
2474 cg
->subsys
[ss
->subsys_id
] = dummytop
->subsys
[ss
->subsys_id
];
2476 } while (l
!= &init_css_set
.list
);
2477 write_unlock(&css_set_lock
);
2479 /* If this subsystem requested that it be notified with fork
2480 * events, we should send it one now for every process in the
2483 struct task_struct
*g
, *p
;
2485 read_lock(&tasklist_lock
);
2486 do_each_thread(g
, p
) {
2488 } while_each_thread(g
, p
);
2489 read_unlock(&tasklist_lock
);
2492 need_forkexit_callback
|= ss
->fork
|| ss
->exit
;
2498 * cgroup_init_early - cgroup initialization at system boot
2500 * Initialize cgroups at system boot, and initialize any
2501 * subsystems that request early init.
2503 int __init
cgroup_init_early(void)
2506 kref_init(&init_css_set
.ref
);
2507 kref_get(&init_css_set
.ref
);
2508 INIT_LIST_HEAD(&init_css_set
.list
);
2509 INIT_LIST_HEAD(&init_css_set
.cg_links
);
2510 INIT_LIST_HEAD(&init_css_set
.tasks
);
2512 init_cgroup_root(&rootnode
);
2513 list_add(&rootnode
.root_list
, &roots
);
2515 init_task
.cgroups
= &init_css_set
;
2517 init_css_set_link
.cg
= &init_css_set
;
2518 list_add(&init_css_set_link
.cgrp_link_list
,
2519 &rootnode
.top_cgroup
.css_sets
);
2520 list_add(&init_css_set_link
.cg_link_list
,
2521 &init_css_set
.cg_links
);
2523 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2524 struct cgroup_subsys
*ss
= subsys
[i
];
2527 BUG_ON(strlen(ss
->name
) > MAX_CGROUP_TYPE_NAMELEN
);
2528 BUG_ON(!ss
->create
);
2529 BUG_ON(!ss
->destroy
);
2530 if (ss
->subsys_id
!= i
) {
2531 printk(KERN_ERR
"cgroup: Subsys %s id == %d\n",
2532 ss
->name
, ss
->subsys_id
);
2537 cgroup_init_subsys(ss
);
2543 * cgroup_init - cgroup initialization
2545 * Register cgroup filesystem and /proc file, and initialize
2546 * any subsystems that didn't request early init.
2548 int __init
cgroup_init(void)
2553 err
= bdi_init(&cgroup_backing_dev_info
);
2557 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2558 struct cgroup_subsys
*ss
= subsys
[i
];
2559 if (!ss
->early_init
)
2560 cgroup_init_subsys(ss
);
2563 err
= register_filesystem(&cgroup_fs_type
);
2567 proc_create("cgroups", 0, NULL
, &proc_cgroupstats_operations
);
2571 bdi_destroy(&cgroup_backing_dev_info
);
2577 * proc_cgroup_show()
2578 * - Print task's cgroup paths into seq_file, one line for each hierarchy
2579 * - Used for /proc/<pid>/cgroup.
2580 * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
2581 * doesn't really matter if tsk->cgroup changes after we read it,
2582 * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
2583 * anyway. No need to check that tsk->cgroup != NULL, thanks to
2584 * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
2585 * cgroup to top_cgroup.
2588 /* TODO: Use a proper seq_file iterator */
2589 static int proc_cgroup_show(struct seq_file
*m
, void *v
)
2592 struct task_struct
*tsk
;
2595 struct cgroupfs_root
*root
;
2598 buf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
2604 tsk
= get_pid_task(pid
, PIDTYPE_PID
);
2610 mutex_lock(&cgroup_mutex
);
2612 for_each_root(root
) {
2613 struct cgroup_subsys
*ss
;
2614 struct cgroup
*cgrp
;
2618 /* Skip this hierarchy if it has no active subsystems */
2619 if (!root
->actual_subsys_bits
)
2621 seq_printf(m
, "%lu:", root
->subsys_bits
);
2622 for_each_subsys(root
, ss
)
2623 seq_printf(m
, "%s%s", count
++ ? "," : "", ss
->name
);
2625 get_first_subsys(&root
->top_cgroup
, NULL
, &subsys_id
);
2626 cgrp
= task_cgroup(tsk
, subsys_id
);
2627 retval
= cgroup_path(cgrp
, buf
, PAGE_SIZE
);
2635 mutex_unlock(&cgroup_mutex
);
2636 put_task_struct(tsk
);
2643 static int cgroup_open(struct inode
*inode
, struct file
*file
)
2645 struct pid
*pid
= PROC_I(inode
)->pid
;
2646 return single_open(file
, proc_cgroup_show
, pid
);
2649 struct file_operations proc_cgroup_operations
= {
2650 .open
= cgroup_open
,
2652 .llseek
= seq_lseek
,
2653 .release
= single_release
,
2656 /* Display information about each subsystem and each hierarchy */
2657 static int proc_cgroupstats_show(struct seq_file
*m
, void *v
)
2661 seq_puts(m
, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
2662 mutex_lock(&cgroup_mutex
);
2663 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2664 struct cgroup_subsys
*ss
= subsys
[i
];
2665 seq_printf(m
, "%s\t%lu\t%d\t%d\n",
2666 ss
->name
, ss
->root
->subsys_bits
,
2667 ss
->root
->number_of_cgroups
, !ss
->disabled
);
2669 mutex_unlock(&cgroup_mutex
);
2673 static int cgroupstats_open(struct inode
*inode
, struct file
*file
)
2675 return single_open(file
, proc_cgroupstats_show
, NULL
);
2678 static struct file_operations proc_cgroupstats_operations
= {
2679 .open
= cgroupstats_open
,
2681 .llseek
= seq_lseek
,
2682 .release
= single_release
,
2686 * cgroup_fork - attach newly forked task to its parents cgroup.
2687 * @child: pointer to task_struct of forking parent process.
2689 * Description: A task inherits its parent's cgroup at fork().
2691 * A pointer to the shared css_set was automatically copied in
2692 * fork.c by dup_task_struct(). However, we ignore that copy, since
2693 * it was not made under the protection of RCU or cgroup_mutex, so
2694 * might no longer be a valid cgroup pointer. cgroup_attach_task() might
2695 * have already changed current->cgroups, allowing the previously
2696 * referenced cgroup group to be removed and freed.
2698 * At the point that cgroup_fork() is called, 'current' is the parent
2699 * task, and the passed argument 'child' points to the child task.
2701 void cgroup_fork(struct task_struct
*child
)
2704 child
->cgroups
= current
->cgroups
;
2705 get_css_set(child
->cgroups
);
2706 task_unlock(current
);
2707 INIT_LIST_HEAD(&child
->cg_list
);
2711 * cgroup_fork_callbacks - run fork callbacks
2712 * @child: the new task
2714 * Called on a new task very soon before adding it to the
2715 * tasklist. No need to take any locks since no-one can
2716 * be operating on this task.
2718 void cgroup_fork_callbacks(struct task_struct
*child
)
2720 if (need_forkexit_callback
) {
2722 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2723 struct cgroup_subsys
*ss
= subsys
[i
];
2725 ss
->fork(ss
, child
);
2731 * cgroup_post_fork - called on a new task after adding it to the task list
2732 * @child: the task in question
2734 * Adds the task to the list running through its css_set if necessary.
2735 * Has to be after the task is visible on the task list in case we race
2736 * with the first call to cgroup_iter_start() - to guarantee that the
2737 * new task ends up on its list.
2739 void cgroup_post_fork(struct task_struct
*child
)
2741 if (use_task_css_set_links
) {
2742 write_lock(&css_set_lock
);
2743 if (list_empty(&child
->cg_list
))
2744 list_add(&child
->cg_list
, &child
->cgroups
->tasks
);
2745 write_unlock(&css_set_lock
);
2749 * cgroup_exit - detach cgroup from exiting task
2750 * @tsk: pointer to task_struct of exiting process
2751 * @run_callback: run exit callbacks?
2753 * Description: Detach cgroup from @tsk and release it.
2755 * Note that cgroups marked notify_on_release force every task in
2756 * them to take the global cgroup_mutex mutex when exiting.
2757 * This could impact scaling on very large systems. Be reluctant to
2758 * use notify_on_release cgroups where very high task exit scaling
2759 * is required on large systems.
2761 * the_top_cgroup_hack:
2763 * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
2765 * We call cgroup_exit() while the task is still competent to
2766 * handle notify_on_release(), then leave the task attached to the
2767 * root cgroup in each hierarchy for the remainder of its exit.
2769 * To do this properly, we would increment the reference count on
2770 * top_cgroup, and near the very end of the kernel/exit.c do_exit()
2771 * code we would add a second cgroup function call, to drop that
2772 * reference. This would just create an unnecessary hot spot on
2773 * the top_cgroup reference count, to no avail.
2775 * Normally, holding a reference to a cgroup without bumping its
2776 * count is unsafe. The cgroup could go away, or someone could
2777 * attach us to a different cgroup, decrementing the count on
2778 * the first cgroup that we never incremented. But in this case,
2779 * top_cgroup isn't going away, and either task has PF_EXITING set,
2780 * which wards off any cgroup_attach_task() attempts, or task is a failed
2781 * fork, never visible to cgroup_attach_task.
2783 void cgroup_exit(struct task_struct
*tsk
, int run_callbacks
)
2788 if (run_callbacks
&& need_forkexit_callback
) {
2789 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2790 struct cgroup_subsys
*ss
= subsys
[i
];
2797 * Unlink from the css_set task list if necessary.
2798 * Optimistically check cg_list before taking
2801 if (!list_empty(&tsk
->cg_list
)) {
2802 write_lock(&css_set_lock
);
2803 if (!list_empty(&tsk
->cg_list
))
2804 list_del(&tsk
->cg_list
);
2805 write_unlock(&css_set_lock
);
2808 /* Reassign the task to the init_css_set. */
2811 tsk
->cgroups
= &init_css_set
;
2814 put_css_set_taskexit(cg
);
2818 * cgroup_clone - clone the cgroup the given subsystem is attached to
2819 * @tsk: the task to be moved
2820 * @subsys: the given subsystem
2822 * Duplicate the current cgroup in the hierarchy that the given
2823 * subsystem is attached to, and move this task into the new
2826 int cgroup_clone(struct task_struct
*tsk
, struct cgroup_subsys
*subsys
)
2828 struct dentry
*dentry
;
2830 char nodename
[MAX_CGROUP_TYPE_NAMELEN
];
2831 struct cgroup
*parent
, *child
;
2832 struct inode
*inode
;
2834 struct cgroupfs_root
*root
;
2835 struct cgroup_subsys
*ss
;
2837 /* We shouldn't be called by an unregistered subsystem */
2838 BUG_ON(!subsys
->active
);
2840 /* First figure out what hierarchy and cgroup we're dealing
2841 * with, and pin them so we can drop cgroup_mutex */
2842 mutex_lock(&cgroup_mutex
);
2844 root
= subsys
->root
;
2845 if (root
== &rootnode
) {
2847 "Not cloning cgroup for unused subsystem %s\n",
2849 mutex_unlock(&cgroup_mutex
);
2853 parent
= task_cgroup(tsk
, subsys
->subsys_id
);
2855 snprintf(nodename
, MAX_CGROUP_TYPE_NAMELEN
, "node_%d", tsk
->pid
);
2857 /* Pin the hierarchy */
2858 atomic_inc(&parent
->root
->sb
->s_active
);
2860 /* Keep the cgroup alive */
2862 mutex_unlock(&cgroup_mutex
);
2864 /* Now do the VFS work to create a cgroup */
2865 inode
= parent
->dentry
->d_inode
;
2867 /* Hold the parent directory mutex across this operation to
2868 * stop anyone else deleting the new cgroup */
2869 mutex_lock(&inode
->i_mutex
);
2870 dentry
= lookup_one_len(nodename
, parent
->dentry
, strlen(nodename
));
2871 if (IS_ERR(dentry
)) {
2873 "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename
,
2875 ret
= PTR_ERR(dentry
);
2879 /* Create the cgroup directory, which also creates the cgroup */
2880 ret
= vfs_mkdir(inode
, dentry
, S_IFDIR
| 0755);
2881 child
= __d_cgrp(dentry
);
2885 "Failed to create cgroup %s: %d\n", nodename
,
2892 "Couldn't find new cgroup %s\n", nodename
);
2897 /* The cgroup now exists. Retake cgroup_mutex and check
2898 * that we're still in the same state that we thought we
2900 mutex_lock(&cgroup_mutex
);
2901 if ((root
!= subsys
->root
) ||
2902 (parent
!= task_cgroup(tsk
, subsys
->subsys_id
))) {
2903 /* Aargh, we raced ... */
2904 mutex_unlock(&inode
->i_mutex
);
2907 deactivate_super(parent
->root
->sb
);
2908 /* The cgroup is still accessible in the VFS, but
2909 * we're not going to try to rmdir() it at this
2912 "Race in cgroup_clone() - leaking cgroup %s\n",
2917 /* do any required auto-setup */
2918 for_each_subsys(root
, ss
) {
2920 ss
->post_clone(ss
, child
);
2923 /* All seems fine. Finish by moving the task into the new cgroup */
2924 ret
= cgroup_attach_task(child
, tsk
);
2925 mutex_unlock(&cgroup_mutex
);
2928 mutex_unlock(&inode
->i_mutex
);
2930 mutex_lock(&cgroup_mutex
);
2932 mutex_unlock(&cgroup_mutex
);
2933 deactivate_super(parent
->root
->sb
);
2938 * cgroup_is_descendant - see if @cgrp is a descendant of current task's cgrp
2939 * @cgrp: the cgroup in question
2941 * See if @cgrp is a descendant of the current task's cgroup in
2942 * the appropriate hierarchy.
2944 * If we are sending in dummytop, then presumably we are creating
2945 * the top cgroup in the subsystem.
2947 * Called only by the ns (nsproxy) cgroup.
2949 int cgroup_is_descendant(const struct cgroup
*cgrp
)
2952 struct cgroup
*target
;
2955 if (cgrp
== dummytop
)
2958 get_first_subsys(cgrp
, NULL
, &subsys_id
);
2959 target
= task_cgroup(current
, subsys_id
);
2960 while (cgrp
!= target
&& cgrp
!= cgrp
->top_cgroup
)
2961 cgrp
= cgrp
->parent
;
2962 ret
= (cgrp
== target
);
2966 static void check_for_release(struct cgroup
*cgrp
)
2968 /* All of these checks rely on RCU to keep the cgroup
2969 * structure alive */
2970 if (cgroup_is_releasable(cgrp
) && !atomic_read(&cgrp
->count
)
2971 && list_empty(&cgrp
->children
) && !cgroup_has_css_refs(cgrp
)) {
2972 /* Control Group is currently removeable. If it's not
2973 * already queued for a userspace notification, queue
2975 int need_schedule_work
= 0;
2976 spin_lock(&release_list_lock
);
2977 if (!cgroup_is_removed(cgrp
) &&
2978 list_empty(&cgrp
->release_list
)) {
2979 list_add(&cgrp
->release_list
, &release_list
);
2980 need_schedule_work
= 1;
2982 spin_unlock(&release_list_lock
);
2983 if (need_schedule_work
)
2984 schedule_work(&release_agent_work
);
2988 void __css_put(struct cgroup_subsys_state
*css
)
2990 struct cgroup
*cgrp
= css
->cgroup
;
2992 if (atomic_dec_and_test(&css
->refcnt
) && notify_on_release(cgrp
)) {
2993 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
2994 check_for_release(cgrp
);
3000 * Notify userspace when a cgroup is released, by running the
3001 * configured release agent with the name of the cgroup (path
3002 * relative to the root of cgroup file system) as the argument.
3004 * Most likely, this user command will try to rmdir this cgroup.
3006 * This races with the possibility that some other task will be
3007 * attached to this cgroup before it is removed, or that some other
3008 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
3009 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
3010 * unused, and this cgroup will be reprieved from its death sentence,
3011 * to continue to serve a useful existence. Next time it's released,
3012 * we will get notified again, if it still has 'notify_on_release' set.
3014 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
3015 * means only wait until the task is successfully execve()'d. The
3016 * separate release agent task is forked by call_usermodehelper(),
3017 * then control in this thread returns here, without waiting for the
3018 * release agent task. We don't bother to wait because the caller of
3019 * this routine has no use for the exit status of the release agent
3020 * task, so no sense holding our caller up for that.
3022 static void cgroup_release_agent(struct work_struct
*work
)
3024 BUG_ON(work
!= &release_agent_work
);
3025 mutex_lock(&cgroup_mutex
);
3026 spin_lock(&release_list_lock
);
3027 while (!list_empty(&release_list
)) {
3028 char *argv
[3], *envp
[3];
3031 struct cgroup
*cgrp
= list_entry(release_list
.next
,
3034 list_del_init(&cgrp
->release_list
);
3035 spin_unlock(&release_list_lock
);
3036 pathbuf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
3038 spin_lock(&release_list_lock
);
3042 if (cgroup_path(cgrp
, pathbuf
, PAGE_SIZE
) < 0) {
3044 spin_lock(&release_list_lock
);
3049 argv
[i
++] = cgrp
->root
->release_agent_path
;
3050 argv
[i
++] = (char *)pathbuf
;
3054 /* minimal command environment */
3055 envp
[i
++] = "HOME=/";
3056 envp
[i
++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
3059 /* Drop the lock while we invoke the usermode helper,
3060 * since the exec could involve hitting disk and hence
3061 * be a slow process */
3062 mutex_unlock(&cgroup_mutex
);
3063 call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_EXEC
);
3065 mutex_lock(&cgroup_mutex
);
3066 spin_lock(&release_list_lock
);
3068 spin_unlock(&release_list_lock
);
3069 mutex_unlock(&cgroup_mutex
);
3072 static int __init
cgroup_disable(char *str
)
3077 while ((token
= strsep(&str
, ",")) != NULL
) {
3081 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
3082 struct cgroup_subsys
*ss
= subsys
[i
];
3084 if (!strcmp(token
, ss
->name
)) {
3086 printk(KERN_INFO
"Disabling %s control group"
3087 " subsystem\n", ss
->name
);
3094 __setup("cgroup_disable=", cgroup_disable
);