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/ctype.h>
27 #include <linux/errno.h>
29 #include <linux/kernel.h>
30 #include <linux/list.h>
32 #include <linux/mutex.h>
33 #include <linux/mount.h>
34 #include <linux/pagemap.h>
35 #include <linux/proc_fs.h>
36 #include <linux/rcupdate.h>
37 #include <linux/sched.h>
38 #include <linux/backing-dev.h>
39 #include <linux/seq_file.h>
40 #include <linux/slab.h>
41 #include <linux/magic.h>
42 #include <linux/spinlock.h>
43 #include <linux/string.h>
44 #include <linux/sort.h>
45 #include <linux/kmod.h>
46 #include <linux/delayacct.h>
47 #include <linux/cgroupstats.h>
48 #include <linux/hash.h>
49 #include <linux/namei.h>
50 #include <linux/smp_lock.h>
51 #include <linux/pid_namespace.h>
52 #include <linux/idr.h>
54 #include <asm/atomic.h>
56 static DEFINE_MUTEX(cgroup_mutex
);
58 /* Generate an array of cgroup subsystem pointers */
59 #define SUBSYS(_x) &_x ## _subsys,
61 static struct cgroup_subsys
*subsys
[] = {
62 #include <linux/cgroup_subsys.h>
65 #define MAX_CGROUP_ROOT_NAMELEN 64
68 * A cgroupfs_root represents the root of a cgroup hierarchy,
69 * and may be associated with a superblock to form an active
72 struct cgroupfs_root
{
73 struct super_block
*sb
;
76 * The bitmask of subsystems intended to be attached to this
79 unsigned long subsys_bits
;
81 /* Unique id for this hierarchy. */
84 /* The bitmask of subsystems currently attached to this hierarchy */
85 unsigned long actual_subsys_bits
;
87 /* A list running through the attached subsystems */
88 struct list_head subsys_list
;
90 /* The root cgroup for this hierarchy */
91 struct cgroup top_cgroup
;
93 /* Tracks how many cgroups are currently defined in hierarchy.*/
94 int number_of_cgroups
;
96 /* A list running through the active hierarchies */
97 struct list_head root_list
;
99 /* Hierarchy-specific flags */
102 /* The path to use for release notifications. */
103 char release_agent_path
[PATH_MAX
];
105 /* The name for this hierarchy - may be empty */
106 char name
[MAX_CGROUP_ROOT_NAMELEN
];
110 * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
111 * subsystems that are otherwise unattached - it never has more than a
112 * single cgroup, and all tasks are part of that cgroup.
114 static struct cgroupfs_root rootnode
;
117 * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
118 * cgroup_subsys->use_id != 0.
120 #define CSS_ID_MAX (65535)
123 * The css to which this ID points. This pointer is set to valid value
124 * after cgroup is populated. If cgroup is removed, this will be NULL.
125 * This pointer is expected to be RCU-safe because destroy()
126 * is called after synchronize_rcu(). But for safe use, css_is_removed()
127 * css_tryget() should be used for avoiding race.
129 struct cgroup_subsys_state
*css
;
135 * Depth in hierarchy which this ID belongs to.
137 unsigned short depth
;
139 * ID is freed by RCU. (and lookup routine is RCU safe.)
141 struct rcu_head rcu_head
;
143 * Hierarchy of CSS ID belongs to.
145 unsigned short stack
[0]; /* Array of Length (depth+1) */
149 /* The list of hierarchy roots */
151 static LIST_HEAD(roots
);
152 static int root_count
;
154 static DEFINE_IDA(hierarchy_ida
);
155 static int next_hierarchy_id
;
156 static DEFINE_SPINLOCK(hierarchy_id_lock
);
158 /* dummytop is a shorthand for the dummy hierarchy's top cgroup */
159 #define dummytop (&rootnode.top_cgroup)
161 /* This flag indicates whether tasks in the fork and exit paths should
162 * check for fork/exit handlers to call. This avoids us having to do
163 * extra work in the fork/exit path if none of the subsystems need to
166 static int need_forkexit_callback __read_mostly
;
168 /* convenient tests for these bits */
169 inline int cgroup_is_removed(const struct cgroup
*cgrp
)
171 return test_bit(CGRP_REMOVED
, &cgrp
->flags
);
174 /* bits in struct cgroupfs_root flags field */
176 ROOT_NOPREFIX
, /* mounted subsystems have no named prefix */
179 static int cgroup_is_releasable(const struct cgroup
*cgrp
)
182 (1 << CGRP_RELEASABLE
) |
183 (1 << CGRP_NOTIFY_ON_RELEASE
);
184 return (cgrp
->flags
& bits
) == bits
;
187 static int notify_on_release(const struct cgroup
*cgrp
)
189 return test_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
193 * for_each_subsys() allows you to iterate on each subsystem attached to
194 * an active hierarchy
196 #define for_each_subsys(_root, _ss) \
197 list_for_each_entry(_ss, &_root->subsys_list, sibling)
199 /* for_each_active_root() allows you to iterate across the active hierarchies */
200 #define for_each_active_root(_root) \
201 list_for_each_entry(_root, &roots, root_list)
203 /* the list of cgroups eligible for automatic release. Protected by
204 * release_list_lock */
205 static LIST_HEAD(release_list
);
206 static DEFINE_SPINLOCK(release_list_lock
);
207 static void cgroup_release_agent(struct work_struct
*work
);
208 static DECLARE_WORK(release_agent_work
, cgroup_release_agent
);
209 static void check_for_release(struct cgroup
*cgrp
);
211 /* Link structure for associating css_set objects with cgroups */
212 struct cg_cgroup_link
{
214 * List running through cg_cgroup_links associated with a
215 * cgroup, anchored on cgroup->css_sets
217 struct list_head cgrp_link_list
;
220 * List running through cg_cgroup_links pointing at a
221 * single css_set object, anchored on css_set->cg_links
223 struct list_head cg_link_list
;
227 /* The default css_set - used by init and its children prior to any
228 * hierarchies being mounted. It contains a pointer to the root state
229 * for each subsystem. Also used to anchor the list of css_sets. Not
230 * reference-counted, to improve performance when child cgroups
231 * haven't been created.
234 static struct css_set init_css_set
;
235 static struct cg_cgroup_link init_css_set_link
;
237 static int cgroup_subsys_init_idr(struct cgroup_subsys
*ss
);
239 /* css_set_lock protects the list of css_set objects, and the
240 * chain of tasks off each css_set. Nests outside task->alloc_lock
241 * due to cgroup_iter_start() */
242 static DEFINE_RWLOCK(css_set_lock
);
243 static int css_set_count
;
246 * hash table for cgroup groups. This improves the performance to find
247 * an existing css_set. This hash doesn't (currently) take into
248 * account cgroups in empty hierarchies.
250 #define CSS_SET_HASH_BITS 7
251 #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS)
252 static struct hlist_head css_set_table
[CSS_SET_TABLE_SIZE
];
254 static struct hlist_head
*css_set_hash(struct cgroup_subsys_state
*css
[])
258 unsigned long tmp
= 0UL;
260 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++)
261 tmp
+= (unsigned long)css
[i
];
262 tmp
= (tmp
>> 16) ^ tmp
;
264 index
= hash_long(tmp
, CSS_SET_HASH_BITS
);
266 return &css_set_table
[index
];
269 /* We don't maintain the lists running through each css_set to its
270 * task until after the first call to cgroup_iter_start(). This
271 * reduces the fork()/exit() overhead for people who have cgroups
272 * compiled into their kernel but not actually in use */
273 static int use_task_css_set_links __read_mostly
;
275 static void __put_css_set(struct css_set
*cg
, int taskexit
)
277 struct cg_cgroup_link
*link
;
278 struct cg_cgroup_link
*saved_link
;
280 * Ensure that the refcount doesn't hit zero while any readers
281 * can see it. Similar to atomic_dec_and_lock(), but for an
284 if (atomic_add_unless(&cg
->refcount
, -1, 1))
286 write_lock(&css_set_lock
);
287 if (!atomic_dec_and_test(&cg
->refcount
)) {
288 write_unlock(&css_set_lock
);
292 /* This css_set is dead. unlink it and release cgroup refcounts */
293 hlist_del(&cg
->hlist
);
296 list_for_each_entry_safe(link
, saved_link
, &cg
->cg_links
,
298 struct cgroup
*cgrp
= link
->cgrp
;
299 list_del(&link
->cg_link_list
);
300 list_del(&link
->cgrp_link_list
);
301 if (atomic_dec_and_test(&cgrp
->count
) &&
302 notify_on_release(cgrp
)) {
304 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
305 check_for_release(cgrp
);
311 write_unlock(&css_set_lock
);
316 * refcounted get/put for css_set objects
318 static inline void get_css_set(struct css_set
*cg
)
320 atomic_inc(&cg
->refcount
);
323 static inline void put_css_set(struct css_set
*cg
)
325 __put_css_set(cg
, 0);
328 static inline void put_css_set_taskexit(struct css_set
*cg
)
330 __put_css_set(cg
, 1);
334 * compare_css_sets - helper function for find_existing_css_set().
335 * @cg: candidate css_set being tested
336 * @old_cg: existing css_set for a task
337 * @new_cgrp: cgroup that's being entered by the task
338 * @template: desired set of css pointers in css_set (pre-calculated)
340 * Returns true if "cg" matches "old_cg" except for the hierarchy
341 * which "new_cgrp" belongs to, for which it should match "new_cgrp".
343 static bool compare_css_sets(struct css_set
*cg
,
344 struct css_set
*old_cg
,
345 struct cgroup
*new_cgrp
,
346 struct cgroup_subsys_state
*template[])
348 struct list_head
*l1
, *l2
;
350 if (memcmp(template, cg
->subsys
, sizeof(cg
->subsys
))) {
351 /* Not all subsystems matched */
356 * Compare cgroup pointers in order to distinguish between
357 * different cgroups in heirarchies with no subsystems. We
358 * could get by with just this check alone (and skip the
359 * memcmp above) but on most setups the memcmp check will
360 * avoid the need for this more expensive check on almost all
365 l2
= &old_cg
->cg_links
;
367 struct cg_cgroup_link
*cgl1
, *cgl2
;
368 struct cgroup
*cg1
, *cg2
;
372 /* See if we reached the end - both lists are equal length. */
373 if (l1
== &cg
->cg_links
) {
374 BUG_ON(l2
!= &old_cg
->cg_links
);
377 BUG_ON(l2
== &old_cg
->cg_links
);
379 /* Locate the cgroups associated with these links. */
380 cgl1
= list_entry(l1
, struct cg_cgroup_link
, cg_link_list
);
381 cgl2
= list_entry(l2
, struct cg_cgroup_link
, cg_link_list
);
384 /* Hierarchies should be linked in the same order. */
385 BUG_ON(cg1
->root
!= cg2
->root
);
388 * If this hierarchy is the hierarchy of the cgroup
389 * that's changing, then we need to check that this
390 * css_set points to the new cgroup; if it's any other
391 * hierarchy, then this css_set should point to the
392 * same cgroup as the old css_set.
394 if (cg1
->root
== new_cgrp
->root
) {
406 * find_existing_css_set() is a helper for
407 * find_css_set(), and checks to see whether an existing
408 * css_set is suitable.
410 * oldcg: the cgroup group that we're using before the cgroup
413 * cgrp: the cgroup that we're moving into
415 * template: location in which to build the desired set of subsystem
416 * state objects for the new cgroup group
418 static struct css_set
*find_existing_css_set(
419 struct css_set
*oldcg
,
421 struct cgroup_subsys_state
*template[])
424 struct cgroupfs_root
*root
= cgrp
->root
;
425 struct hlist_head
*hhead
;
426 struct hlist_node
*node
;
429 /* Built the set of subsystem state objects that we want to
430 * see in the new css_set */
431 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
432 if (root
->subsys_bits
& (1UL << i
)) {
433 /* Subsystem is in this hierarchy. So we want
434 * the subsystem state from the new
436 template[i
] = cgrp
->subsys
[i
];
438 /* Subsystem is not in this hierarchy, so we
439 * don't want to change the subsystem state */
440 template[i
] = oldcg
->subsys
[i
];
444 hhead
= css_set_hash(template);
445 hlist_for_each_entry(cg
, node
, hhead
, hlist
) {
446 if (!compare_css_sets(cg
, oldcg
, cgrp
, template))
449 /* This css_set matches what we need */
453 /* No existing cgroup group matched */
457 static void free_cg_links(struct list_head
*tmp
)
459 struct cg_cgroup_link
*link
;
460 struct cg_cgroup_link
*saved_link
;
462 list_for_each_entry_safe(link
, saved_link
, tmp
, cgrp_link_list
) {
463 list_del(&link
->cgrp_link_list
);
469 * allocate_cg_links() allocates "count" cg_cgroup_link structures
470 * and chains them on tmp through their cgrp_link_list fields. Returns 0 on
471 * success or a negative error
473 static int allocate_cg_links(int count
, struct list_head
*tmp
)
475 struct cg_cgroup_link
*link
;
478 for (i
= 0; i
< count
; i
++) {
479 link
= kmalloc(sizeof(*link
), GFP_KERNEL
);
484 list_add(&link
->cgrp_link_list
, tmp
);
490 * link_css_set - a helper function to link a css_set to a cgroup
491 * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links()
492 * @cg: the css_set to be linked
493 * @cgrp: the destination cgroup
495 static void link_css_set(struct list_head
*tmp_cg_links
,
496 struct css_set
*cg
, struct cgroup
*cgrp
)
498 struct cg_cgroup_link
*link
;
500 BUG_ON(list_empty(tmp_cg_links
));
501 link
= list_first_entry(tmp_cg_links
, struct cg_cgroup_link
,
505 atomic_inc(&cgrp
->count
);
506 list_move(&link
->cgrp_link_list
, &cgrp
->css_sets
);
508 * Always add links to the tail of the list so that the list
509 * is sorted by order of hierarchy creation
511 list_add_tail(&link
->cg_link_list
, &cg
->cg_links
);
515 * find_css_set() takes an existing cgroup group and a
516 * cgroup object, and returns a css_set object that's
517 * equivalent to the old group, but with the given cgroup
518 * substituted into the appropriate hierarchy. Must be called with
521 static struct css_set
*find_css_set(
522 struct css_set
*oldcg
, struct cgroup
*cgrp
)
525 struct cgroup_subsys_state
*template[CGROUP_SUBSYS_COUNT
];
527 struct list_head tmp_cg_links
;
529 struct hlist_head
*hhead
;
530 struct cg_cgroup_link
*link
;
532 /* First see if we already have a cgroup group that matches
534 read_lock(&css_set_lock
);
535 res
= find_existing_css_set(oldcg
, cgrp
, template);
538 read_unlock(&css_set_lock
);
543 res
= kmalloc(sizeof(*res
), GFP_KERNEL
);
547 /* Allocate all the cg_cgroup_link objects that we'll need */
548 if (allocate_cg_links(root_count
, &tmp_cg_links
) < 0) {
553 atomic_set(&res
->refcount
, 1);
554 INIT_LIST_HEAD(&res
->cg_links
);
555 INIT_LIST_HEAD(&res
->tasks
);
556 INIT_HLIST_NODE(&res
->hlist
);
558 /* Copy the set of subsystem state objects generated in
559 * find_existing_css_set() */
560 memcpy(res
->subsys
, template, sizeof(res
->subsys
));
562 write_lock(&css_set_lock
);
563 /* Add reference counts and links from the new css_set. */
564 list_for_each_entry(link
, &oldcg
->cg_links
, cg_link_list
) {
565 struct cgroup
*c
= link
->cgrp
;
566 if (c
->root
== cgrp
->root
)
568 link_css_set(&tmp_cg_links
, res
, c
);
571 BUG_ON(!list_empty(&tmp_cg_links
));
575 /* Add this cgroup group to the hash table */
576 hhead
= css_set_hash(res
->subsys
);
577 hlist_add_head(&res
->hlist
, hhead
);
579 write_unlock(&css_set_lock
);
585 * Return the cgroup for "task" from the given hierarchy. Must be
586 * called with cgroup_mutex held.
588 static struct cgroup
*task_cgroup_from_root(struct task_struct
*task
,
589 struct cgroupfs_root
*root
)
592 struct cgroup
*res
= NULL
;
594 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
595 read_lock(&css_set_lock
);
597 * No need to lock the task - since we hold cgroup_mutex the
598 * task can't change groups, so the only thing that can happen
599 * is that it exits and its css is set back to init_css_set.
602 if (css
== &init_css_set
) {
603 res
= &root
->top_cgroup
;
605 struct cg_cgroup_link
*link
;
606 list_for_each_entry(link
, &css
->cg_links
, cg_link_list
) {
607 struct cgroup
*c
= link
->cgrp
;
608 if (c
->root
== root
) {
614 read_unlock(&css_set_lock
);
620 * There is one global cgroup mutex. We also require taking
621 * task_lock() when dereferencing a task's cgroup subsys pointers.
622 * See "The task_lock() exception", at the end of this comment.
624 * A task must hold cgroup_mutex to modify cgroups.
626 * Any task can increment and decrement the count field without lock.
627 * So in general, code holding cgroup_mutex can't rely on the count
628 * field not changing. However, if the count goes to zero, then only
629 * cgroup_attach_task() can increment it again. Because a count of zero
630 * means that no tasks are currently attached, therefore there is no
631 * way a task attached to that cgroup can fork (the other way to
632 * increment the count). So code holding cgroup_mutex can safely
633 * assume that if the count is zero, it will stay zero. Similarly, if
634 * a task holds cgroup_mutex on a cgroup with zero count, it
635 * knows that the cgroup won't be removed, as cgroup_rmdir()
638 * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
639 * (usually) take cgroup_mutex. These are the two most performance
640 * critical pieces of code here. The exception occurs on cgroup_exit(),
641 * when a task in a notify_on_release cgroup exits. Then cgroup_mutex
642 * is taken, and if the cgroup count is zero, a usermode call made
643 * to the release agent with the name of the cgroup (path relative to
644 * the root of cgroup file system) as the argument.
646 * A cgroup can only be deleted if both its 'count' of using tasks
647 * is zero, and its list of 'children' cgroups is empty. Since all
648 * tasks in the system use _some_ cgroup, and since there is always at
649 * least one task in the system (init, pid == 1), therefore, top_cgroup
650 * always has either children cgroups and/or using tasks. So we don't
651 * need a special hack to ensure that top_cgroup cannot be deleted.
653 * The task_lock() exception
655 * The need for this exception arises from the action of
656 * cgroup_attach_task(), which overwrites one tasks cgroup pointer with
657 * another. It does so using cgroup_mutex, however there are
658 * several performance critical places that need to reference
659 * task->cgroup without the expense of grabbing a system global
660 * mutex. Therefore except as noted below, when dereferencing or, as
661 * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use
662 * task_lock(), which acts on a spinlock (task->alloc_lock) already in
663 * the task_struct routinely used for such matters.
665 * P.S. One more locking exception. RCU is used to guard the
666 * update of a tasks cgroup pointer by cgroup_attach_task()
670 * cgroup_lock - lock out any changes to cgroup structures
673 void cgroup_lock(void)
675 mutex_lock(&cgroup_mutex
);
679 * cgroup_unlock - release lock on cgroup changes
681 * Undo the lock taken in a previous cgroup_lock() call.
683 void cgroup_unlock(void)
685 mutex_unlock(&cgroup_mutex
);
689 * A couple of forward declarations required, due to cyclic reference loop:
690 * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
691 * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
695 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
);
696 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
);
697 static int cgroup_populate_dir(struct cgroup
*cgrp
);
698 static const struct inode_operations cgroup_dir_inode_operations
;
699 static struct file_operations proc_cgroupstats_operations
;
701 static struct backing_dev_info cgroup_backing_dev_info
= {
703 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
,
706 static int alloc_css_id(struct cgroup_subsys
*ss
,
707 struct cgroup
*parent
, struct cgroup
*child
);
709 static struct inode
*cgroup_new_inode(mode_t mode
, struct super_block
*sb
)
711 struct inode
*inode
= new_inode(sb
);
714 inode
->i_mode
= mode
;
715 inode
->i_uid
= current_fsuid();
716 inode
->i_gid
= current_fsgid();
717 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
718 inode
->i_mapping
->backing_dev_info
= &cgroup_backing_dev_info
;
724 * Call subsys's pre_destroy handler.
725 * This is called before css refcnt check.
727 static int cgroup_call_pre_destroy(struct cgroup
*cgrp
)
729 struct cgroup_subsys
*ss
;
732 for_each_subsys(cgrp
->root
, ss
)
733 if (ss
->pre_destroy
) {
734 ret
= ss
->pre_destroy(ss
, cgrp
);
741 static void free_cgroup_rcu(struct rcu_head
*obj
)
743 struct cgroup
*cgrp
= container_of(obj
, struct cgroup
, rcu_head
);
748 static void cgroup_diput(struct dentry
*dentry
, struct inode
*inode
)
750 /* is dentry a directory ? if so, kfree() associated cgroup */
751 if (S_ISDIR(inode
->i_mode
)) {
752 struct cgroup
*cgrp
= dentry
->d_fsdata
;
753 struct cgroup_subsys
*ss
;
754 BUG_ON(!(cgroup_is_removed(cgrp
)));
755 /* It's possible for external users to be holding css
756 * reference counts on a cgroup; css_put() needs to
757 * be able to access the cgroup after decrementing
758 * the reference count in order to know if it needs to
759 * queue the cgroup to be handled by the release
763 mutex_lock(&cgroup_mutex
);
765 * Release the subsystem state objects.
767 for_each_subsys(cgrp
->root
, ss
)
768 ss
->destroy(ss
, cgrp
);
770 cgrp
->root
->number_of_cgroups
--;
771 mutex_unlock(&cgroup_mutex
);
774 * Drop the active superblock reference that we took when we
777 deactivate_super(cgrp
->root
->sb
);
779 call_rcu(&cgrp
->rcu_head
, free_cgroup_rcu
);
784 static void remove_dir(struct dentry
*d
)
786 struct dentry
*parent
= dget(d
->d_parent
);
789 simple_rmdir(parent
->d_inode
, d
);
793 static void cgroup_clear_directory(struct dentry
*dentry
)
795 struct list_head
*node
;
797 BUG_ON(!mutex_is_locked(&dentry
->d_inode
->i_mutex
));
798 spin_lock(&dcache_lock
);
799 node
= dentry
->d_subdirs
.next
;
800 while (node
!= &dentry
->d_subdirs
) {
801 struct dentry
*d
= list_entry(node
, struct dentry
, d_u
.d_child
);
804 /* This should never be called on a cgroup
805 * directory with child cgroups */
806 BUG_ON(d
->d_inode
->i_mode
& S_IFDIR
);
808 spin_unlock(&dcache_lock
);
810 simple_unlink(dentry
->d_inode
, d
);
812 spin_lock(&dcache_lock
);
814 node
= dentry
->d_subdirs
.next
;
816 spin_unlock(&dcache_lock
);
820 * NOTE : the dentry must have been dget()'ed
822 static void cgroup_d_remove_dir(struct dentry
*dentry
)
824 cgroup_clear_directory(dentry
);
826 spin_lock(&dcache_lock
);
827 list_del_init(&dentry
->d_u
.d_child
);
828 spin_unlock(&dcache_lock
);
833 * A queue for waiters to do rmdir() cgroup. A tasks will sleep when
834 * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some
835 * reference to css->refcnt. In general, this refcnt is expected to goes down
838 * CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex;
840 DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq
);
842 static void cgroup_wakeup_rmdir_waiter(struct cgroup
*cgrp
)
844 if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
)))
845 wake_up_all(&cgroup_rmdir_waitq
);
848 void cgroup_exclude_rmdir(struct cgroup_subsys_state
*css
)
853 void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state
*css
)
855 cgroup_wakeup_rmdir_waiter(css
->cgroup
);
860 static int rebind_subsystems(struct cgroupfs_root
*root
,
861 unsigned long final_bits
)
863 unsigned long added_bits
, removed_bits
;
864 struct cgroup
*cgrp
= &root
->top_cgroup
;
867 removed_bits
= root
->actual_subsys_bits
& ~final_bits
;
868 added_bits
= final_bits
& ~root
->actual_subsys_bits
;
869 /* Check that any added subsystems are currently free */
870 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
871 unsigned long bit
= 1UL << i
;
872 struct cgroup_subsys
*ss
= subsys
[i
];
873 if (!(bit
& added_bits
))
875 if (ss
->root
!= &rootnode
) {
876 /* Subsystem isn't free */
881 /* Currently we don't handle adding/removing subsystems when
882 * any child cgroups exist. This is theoretically supportable
883 * but involves complex error handling, so it's being left until
885 if (root
->number_of_cgroups
> 1)
888 /* Process each subsystem */
889 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
890 struct cgroup_subsys
*ss
= subsys
[i
];
891 unsigned long bit
= 1UL << i
;
892 if (bit
& added_bits
) {
893 /* We're binding this subsystem to this hierarchy */
894 BUG_ON(cgrp
->subsys
[i
]);
895 BUG_ON(!dummytop
->subsys
[i
]);
896 BUG_ON(dummytop
->subsys
[i
]->cgroup
!= dummytop
);
897 mutex_lock(&ss
->hierarchy_mutex
);
898 cgrp
->subsys
[i
] = dummytop
->subsys
[i
];
899 cgrp
->subsys
[i
]->cgroup
= cgrp
;
900 list_move(&ss
->sibling
, &root
->subsys_list
);
904 mutex_unlock(&ss
->hierarchy_mutex
);
905 } else if (bit
& removed_bits
) {
906 /* We're removing this subsystem */
907 BUG_ON(cgrp
->subsys
[i
] != dummytop
->subsys
[i
]);
908 BUG_ON(cgrp
->subsys
[i
]->cgroup
!= cgrp
);
909 mutex_lock(&ss
->hierarchy_mutex
);
911 ss
->bind(ss
, dummytop
);
912 dummytop
->subsys
[i
]->cgroup
= dummytop
;
913 cgrp
->subsys
[i
] = NULL
;
914 subsys
[i
]->root
= &rootnode
;
915 list_move(&ss
->sibling
, &rootnode
.subsys_list
);
916 mutex_unlock(&ss
->hierarchy_mutex
);
917 } else if (bit
& final_bits
) {
918 /* Subsystem state should already exist */
919 BUG_ON(!cgrp
->subsys
[i
]);
921 /* Subsystem state shouldn't exist */
922 BUG_ON(cgrp
->subsys
[i
]);
925 root
->subsys_bits
= root
->actual_subsys_bits
= final_bits
;
931 static int cgroup_show_options(struct seq_file
*seq
, struct vfsmount
*vfs
)
933 struct cgroupfs_root
*root
= vfs
->mnt_sb
->s_fs_info
;
934 struct cgroup_subsys
*ss
;
936 mutex_lock(&cgroup_mutex
);
937 for_each_subsys(root
, ss
)
938 seq_printf(seq
, ",%s", ss
->name
);
939 if (test_bit(ROOT_NOPREFIX
, &root
->flags
))
940 seq_puts(seq
, ",noprefix");
941 if (strlen(root
->release_agent_path
))
942 seq_printf(seq
, ",release_agent=%s", root
->release_agent_path
);
943 if (strlen(root
->name
))
944 seq_printf(seq
, ",name=%s", root
->name
);
945 mutex_unlock(&cgroup_mutex
);
949 struct cgroup_sb_opts
{
950 unsigned long subsys_bits
;
954 /* User explicitly requested empty subsystem */
957 struct cgroupfs_root
*new_root
;
961 /* Convert a hierarchy specifier into a bitmask of subsystems and
963 static int parse_cgroupfs_options(char *data
,
964 struct cgroup_sb_opts
*opts
)
966 char *token
, *o
= data
?: "all";
967 unsigned long mask
= (unsigned long)-1;
969 #ifdef CONFIG_CPUSETS
970 mask
= ~(1UL << cpuset_subsys_id
);
973 memset(opts
, 0, sizeof(*opts
));
975 while ((token
= strsep(&o
, ",")) != NULL
) {
978 if (!strcmp(token
, "all")) {
979 /* Add all non-disabled subsystems */
981 opts
->subsys_bits
= 0;
982 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
983 struct cgroup_subsys
*ss
= subsys
[i
];
985 opts
->subsys_bits
|= 1ul << i
;
987 } else if (!strcmp(token
, "none")) {
988 /* Explicitly have no subsystems */
990 } else if (!strcmp(token
, "noprefix")) {
991 set_bit(ROOT_NOPREFIX
, &opts
->flags
);
992 } else if (!strncmp(token
, "release_agent=", 14)) {
993 /* Specifying two release agents is forbidden */
994 if (opts
->release_agent
)
996 opts
->release_agent
=
997 kstrndup(token
+ 14, PATH_MAX
, GFP_KERNEL
);
998 if (!opts
->release_agent
)
1000 } else if (!strncmp(token
, "name=", 5)) {
1002 const char *name
= token
+ 5;
1003 /* Can't specify an empty name */
1006 /* Must match [\w.-]+ */
1007 for (i
= 0; i
< strlen(name
); i
++) {
1011 if ((c
== '.') || (c
== '-') || (c
== '_'))
1015 /* Specifying two names is forbidden */
1018 opts
->name
= kstrndup(name
,
1019 MAX_CGROUP_ROOT_NAMELEN
,
1024 struct cgroup_subsys
*ss
;
1026 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1028 if (!strcmp(token
, ss
->name
)) {
1030 set_bit(i
, &opts
->subsys_bits
);
1034 if (i
== CGROUP_SUBSYS_COUNT
)
1039 /* Consistency checks */
1042 * Option noprefix was introduced just for backward compatibility
1043 * with the old cpuset, so we allow noprefix only if mounting just
1044 * the cpuset subsystem.
1046 if (test_bit(ROOT_NOPREFIX
, &opts
->flags
) &&
1047 (opts
->subsys_bits
& mask
))
1051 /* Can't specify "none" and some subsystems */
1052 if (opts
->subsys_bits
&& opts
->none
)
1056 * We either have to specify by name or by subsystems. (So all
1057 * empty hierarchies must have a name).
1059 if (!opts
->subsys_bits
&& !opts
->name
)
1065 static int cgroup_remount(struct super_block
*sb
, int *flags
, char *data
)
1068 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1069 struct cgroup
*cgrp
= &root
->top_cgroup
;
1070 struct cgroup_sb_opts opts
;
1073 mutex_lock(&cgrp
->dentry
->d_inode
->i_mutex
);
1074 mutex_lock(&cgroup_mutex
);
1076 /* See what subsystems are wanted */
1077 ret
= parse_cgroupfs_options(data
, &opts
);
1081 /* Don't allow flags to change at remount */
1082 if (opts
.flags
!= root
->flags
) {
1087 /* Don't allow name to change at remount */
1088 if (opts
.name
&& strcmp(opts
.name
, root
->name
)) {
1093 ret
= rebind_subsystems(root
, opts
.subsys_bits
);
1097 /* (re)populate subsystem files */
1098 cgroup_populate_dir(cgrp
);
1100 if (opts
.release_agent
)
1101 strcpy(root
->release_agent_path
, opts
.release_agent
);
1103 kfree(opts
.release_agent
);
1105 mutex_unlock(&cgroup_mutex
);
1106 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
1111 static const struct super_operations cgroup_ops
= {
1112 .statfs
= simple_statfs
,
1113 .drop_inode
= generic_delete_inode
,
1114 .show_options
= cgroup_show_options
,
1115 .remount_fs
= cgroup_remount
,
1118 static void init_cgroup_housekeeping(struct cgroup
*cgrp
)
1120 INIT_LIST_HEAD(&cgrp
->sibling
);
1121 INIT_LIST_HEAD(&cgrp
->children
);
1122 INIT_LIST_HEAD(&cgrp
->css_sets
);
1123 INIT_LIST_HEAD(&cgrp
->release_list
);
1124 INIT_LIST_HEAD(&cgrp
->pids_list
);
1125 init_rwsem(&cgrp
->pids_mutex
);
1128 static void init_cgroup_root(struct cgroupfs_root
*root
)
1130 struct cgroup
*cgrp
= &root
->top_cgroup
;
1131 INIT_LIST_HEAD(&root
->subsys_list
);
1132 INIT_LIST_HEAD(&root
->root_list
);
1133 root
->number_of_cgroups
= 1;
1135 cgrp
->top_cgroup
= cgrp
;
1136 init_cgroup_housekeeping(cgrp
);
1139 static bool init_root_id(struct cgroupfs_root
*root
)
1144 if (!ida_pre_get(&hierarchy_ida
, GFP_KERNEL
))
1146 spin_lock(&hierarchy_id_lock
);
1147 /* Try to allocate the next unused ID */
1148 ret
= ida_get_new_above(&hierarchy_ida
, next_hierarchy_id
,
1149 &root
->hierarchy_id
);
1151 /* Try again starting from 0 */
1152 ret
= ida_get_new(&hierarchy_ida
, &root
->hierarchy_id
);
1154 next_hierarchy_id
= root
->hierarchy_id
+ 1;
1155 } else if (ret
!= -EAGAIN
) {
1156 /* Can only get here if the 31-bit IDR is full ... */
1159 spin_unlock(&hierarchy_id_lock
);
1164 static int cgroup_test_super(struct super_block
*sb
, void *data
)
1166 struct cgroup_sb_opts
*opts
= data
;
1167 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1169 /* If we asked for a name then it must match */
1170 if (opts
->name
&& strcmp(opts
->name
, root
->name
))
1174 * If we asked for subsystems (or explicitly for no
1175 * subsystems) then they must match
1177 if ((opts
->subsys_bits
|| opts
->none
)
1178 && (opts
->subsys_bits
!= root
->subsys_bits
))
1184 static struct cgroupfs_root
*cgroup_root_from_opts(struct cgroup_sb_opts
*opts
)
1186 struct cgroupfs_root
*root
;
1188 if (!opts
->subsys_bits
&& !opts
->none
)
1191 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
1193 return ERR_PTR(-ENOMEM
);
1195 if (!init_root_id(root
)) {
1197 return ERR_PTR(-ENOMEM
);
1199 init_cgroup_root(root
);
1201 root
->subsys_bits
= opts
->subsys_bits
;
1202 root
->flags
= opts
->flags
;
1203 if (opts
->release_agent
)
1204 strcpy(root
->release_agent_path
, opts
->release_agent
);
1206 strcpy(root
->name
, opts
->name
);
1210 static void cgroup_drop_root(struct cgroupfs_root
*root
)
1215 BUG_ON(!root
->hierarchy_id
);
1216 spin_lock(&hierarchy_id_lock
);
1217 ida_remove(&hierarchy_ida
, root
->hierarchy_id
);
1218 spin_unlock(&hierarchy_id_lock
);
1222 static int cgroup_set_super(struct super_block
*sb
, void *data
)
1225 struct cgroup_sb_opts
*opts
= data
;
1227 /* If we don't have a new root, we can't set up a new sb */
1228 if (!opts
->new_root
)
1231 BUG_ON(!opts
->subsys_bits
&& !opts
->none
);
1233 ret
= set_anon_super(sb
, NULL
);
1237 sb
->s_fs_info
= opts
->new_root
;
1238 opts
->new_root
->sb
= sb
;
1240 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
1241 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
1242 sb
->s_magic
= CGROUP_SUPER_MAGIC
;
1243 sb
->s_op
= &cgroup_ops
;
1248 static int cgroup_get_rootdir(struct super_block
*sb
)
1250 struct inode
*inode
=
1251 cgroup_new_inode(S_IFDIR
| S_IRUGO
| S_IXUGO
| S_IWUSR
, sb
);
1252 struct dentry
*dentry
;
1257 inode
->i_fop
= &simple_dir_operations
;
1258 inode
->i_op
= &cgroup_dir_inode_operations
;
1259 /* directories start off with i_nlink == 2 (for "." entry) */
1261 dentry
= d_alloc_root(inode
);
1266 sb
->s_root
= dentry
;
1270 static int cgroup_get_sb(struct file_system_type
*fs_type
,
1271 int flags
, const char *unused_dev_name
,
1272 void *data
, struct vfsmount
*mnt
)
1274 struct cgroup_sb_opts opts
;
1275 struct cgroupfs_root
*root
;
1277 struct super_block
*sb
;
1278 struct cgroupfs_root
*new_root
;
1280 /* First find the desired set of subsystems */
1281 ret
= parse_cgroupfs_options(data
, &opts
);
1286 * Allocate a new cgroup root. We may not need it if we're
1287 * reusing an existing hierarchy.
1289 new_root
= cgroup_root_from_opts(&opts
);
1290 if (IS_ERR(new_root
)) {
1291 ret
= PTR_ERR(new_root
);
1294 opts
.new_root
= new_root
;
1296 /* Locate an existing or new sb for this hierarchy */
1297 sb
= sget(fs_type
, cgroup_test_super
, cgroup_set_super
, &opts
);
1300 cgroup_drop_root(opts
.new_root
);
1304 root
= sb
->s_fs_info
;
1306 if (root
== opts
.new_root
) {
1307 /* We used the new root structure, so this is a new hierarchy */
1308 struct list_head tmp_cg_links
;
1309 struct cgroup
*root_cgrp
= &root
->top_cgroup
;
1310 struct inode
*inode
;
1311 struct cgroupfs_root
*existing_root
;
1314 BUG_ON(sb
->s_root
!= NULL
);
1316 ret
= cgroup_get_rootdir(sb
);
1318 goto drop_new_super
;
1319 inode
= sb
->s_root
->d_inode
;
1321 mutex_lock(&inode
->i_mutex
);
1322 mutex_lock(&cgroup_mutex
);
1324 if (strlen(root
->name
)) {
1325 /* Check for name clashes with existing mounts */
1326 for_each_active_root(existing_root
) {
1327 if (!strcmp(existing_root
->name
, root
->name
)) {
1329 mutex_unlock(&cgroup_mutex
);
1330 mutex_unlock(&inode
->i_mutex
);
1331 goto drop_new_super
;
1337 * We're accessing css_set_count without locking
1338 * css_set_lock here, but that's OK - it can only be
1339 * increased by someone holding cgroup_lock, and
1340 * that's us. The worst that can happen is that we
1341 * have some link structures left over
1343 ret
= allocate_cg_links(css_set_count
, &tmp_cg_links
);
1345 mutex_unlock(&cgroup_mutex
);
1346 mutex_unlock(&inode
->i_mutex
);
1347 goto drop_new_super
;
1350 ret
= rebind_subsystems(root
, root
->subsys_bits
);
1351 if (ret
== -EBUSY
) {
1352 mutex_unlock(&cgroup_mutex
);
1353 mutex_unlock(&inode
->i_mutex
);
1354 free_cg_links(&tmp_cg_links
);
1355 goto drop_new_super
;
1358 /* EBUSY should be the only error here */
1361 list_add(&root
->root_list
, &roots
);
1364 sb
->s_root
->d_fsdata
= root_cgrp
;
1365 root
->top_cgroup
.dentry
= sb
->s_root
;
1367 /* Link the top cgroup in this hierarchy into all
1368 * the css_set objects */
1369 write_lock(&css_set_lock
);
1370 for (i
= 0; i
< CSS_SET_TABLE_SIZE
; i
++) {
1371 struct hlist_head
*hhead
= &css_set_table
[i
];
1372 struct hlist_node
*node
;
1375 hlist_for_each_entry(cg
, node
, hhead
, hlist
)
1376 link_css_set(&tmp_cg_links
, cg
, root_cgrp
);
1378 write_unlock(&css_set_lock
);
1380 free_cg_links(&tmp_cg_links
);
1382 BUG_ON(!list_empty(&root_cgrp
->sibling
));
1383 BUG_ON(!list_empty(&root_cgrp
->children
));
1384 BUG_ON(root
->number_of_cgroups
!= 1);
1386 cgroup_populate_dir(root_cgrp
);
1387 mutex_unlock(&cgroup_mutex
);
1388 mutex_unlock(&inode
->i_mutex
);
1391 * We re-used an existing hierarchy - the new root (if
1392 * any) is not needed
1394 cgroup_drop_root(opts
.new_root
);
1397 simple_set_mnt(mnt
, sb
);
1398 kfree(opts
.release_agent
);
1403 deactivate_locked_super(sb
);
1405 kfree(opts
.release_agent
);
1411 static void cgroup_kill_sb(struct super_block
*sb
) {
1412 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1413 struct cgroup
*cgrp
= &root
->top_cgroup
;
1415 struct cg_cgroup_link
*link
;
1416 struct cg_cgroup_link
*saved_link
;
1420 BUG_ON(root
->number_of_cgroups
!= 1);
1421 BUG_ON(!list_empty(&cgrp
->children
));
1422 BUG_ON(!list_empty(&cgrp
->sibling
));
1424 mutex_lock(&cgroup_mutex
);
1426 /* Rebind all subsystems back to the default hierarchy */
1427 ret
= rebind_subsystems(root
, 0);
1428 /* Shouldn't be able to fail ... */
1432 * Release all the links from css_sets to this hierarchy's
1435 write_lock(&css_set_lock
);
1437 list_for_each_entry_safe(link
, saved_link
, &cgrp
->css_sets
,
1439 list_del(&link
->cg_link_list
);
1440 list_del(&link
->cgrp_link_list
);
1443 write_unlock(&css_set_lock
);
1445 if (!list_empty(&root
->root_list
)) {
1446 list_del(&root
->root_list
);
1450 mutex_unlock(&cgroup_mutex
);
1452 kill_litter_super(sb
);
1453 cgroup_drop_root(root
);
1456 static struct file_system_type cgroup_fs_type
= {
1458 .get_sb
= cgroup_get_sb
,
1459 .kill_sb
= cgroup_kill_sb
,
1462 static inline struct cgroup
*__d_cgrp(struct dentry
*dentry
)
1464 return dentry
->d_fsdata
;
1467 static inline struct cftype
*__d_cft(struct dentry
*dentry
)
1469 return dentry
->d_fsdata
;
1473 * cgroup_path - generate the path of a cgroup
1474 * @cgrp: the cgroup in question
1475 * @buf: the buffer to write the path into
1476 * @buflen: the length of the buffer
1478 * Called with cgroup_mutex held or else with an RCU-protected cgroup
1479 * reference. Writes path of cgroup into buf. Returns 0 on success,
1482 int cgroup_path(const struct cgroup
*cgrp
, char *buf
, int buflen
)
1485 struct dentry
*dentry
= rcu_dereference(cgrp
->dentry
);
1487 if (!dentry
|| cgrp
== dummytop
) {
1489 * Inactive subsystems have no dentry for their root
1496 start
= buf
+ buflen
;
1500 int len
= dentry
->d_name
.len
;
1501 if ((start
-= len
) < buf
)
1502 return -ENAMETOOLONG
;
1503 memcpy(start
, cgrp
->dentry
->d_name
.name
, len
);
1504 cgrp
= cgrp
->parent
;
1507 dentry
= rcu_dereference(cgrp
->dentry
);
1511 return -ENAMETOOLONG
;
1514 memmove(buf
, start
, buf
+ buflen
- start
);
1519 * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp'
1520 * @cgrp: the cgroup the task is attaching to
1521 * @tsk: the task to be attached
1523 * Call holding cgroup_mutex. May take task_lock of
1524 * the task 'tsk' during call.
1526 int cgroup_attach_task(struct cgroup
*cgrp
, struct task_struct
*tsk
)
1529 struct cgroup_subsys
*ss
;
1530 struct cgroup
*oldcgrp
;
1532 struct css_set
*newcg
;
1533 struct cgroupfs_root
*root
= cgrp
->root
;
1535 /* Nothing to do if the task is already in that cgroup */
1536 oldcgrp
= task_cgroup_from_root(tsk
, root
);
1537 if (cgrp
== oldcgrp
)
1540 for_each_subsys(root
, ss
) {
1541 if (ss
->can_attach
) {
1542 retval
= ss
->can_attach(ss
, cgrp
, tsk
);
1553 * Locate or allocate a new css_set for this task,
1554 * based on its final set of cgroups
1556 newcg
= find_css_set(cg
, cgrp
);
1562 if (tsk
->flags
& PF_EXITING
) {
1567 rcu_assign_pointer(tsk
->cgroups
, newcg
);
1570 /* Update the css_set linked lists if we're using them */
1571 write_lock(&css_set_lock
);
1572 if (!list_empty(&tsk
->cg_list
)) {
1573 list_del(&tsk
->cg_list
);
1574 list_add(&tsk
->cg_list
, &newcg
->tasks
);
1576 write_unlock(&css_set_lock
);
1578 for_each_subsys(root
, ss
) {
1580 ss
->attach(ss
, cgrp
, oldcgrp
, tsk
);
1582 set_bit(CGRP_RELEASABLE
, &oldcgrp
->flags
);
1587 * wake up rmdir() waiter. the rmdir should fail since the cgroup
1588 * is no longer empty.
1590 cgroup_wakeup_rmdir_waiter(cgrp
);
1595 * Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex
1596 * held. May take task_lock of task
1598 static int attach_task_by_pid(struct cgroup
*cgrp
, u64 pid
)
1600 struct task_struct
*tsk
;
1601 const struct cred
*cred
= current_cred(), *tcred
;
1606 tsk
= find_task_by_vpid(pid
);
1607 if (!tsk
|| tsk
->flags
& PF_EXITING
) {
1612 tcred
= __task_cred(tsk
);
1614 cred
->euid
!= tcred
->uid
&&
1615 cred
->euid
!= tcred
->suid
) {
1619 get_task_struct(tsk
);
1623 get_task_struct(tsk
);
1626 ret
= cgroup_attach_task(cgrp
, tsk
);
1627 put_task_struct(tsk
);
1631 static int cgroup_tasks_write(struct cgroup
*cgrp
, struct cftype
*cft
, u64 pid
)
1634 if (!cgroup_lock_live_group(cgrp
))
1636 ret
= attach_task_by_pid(cgrp
, pid
);
1641 /* The various types of files and directories in a cgroup file system */
1642 enum cgroup_filetype
{
1646 FILE_NOTIFY_ON_RELEASE
,
1651 * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
1652 * @cgrp: the cgroup to be checked for liveness
1654 * On success, returns true; the lock should be later released with
1655 * cgroup_unlock(). On failure returns false with no lock held.
1657 bool cgroup_lock_live_group(struct cgroup
*cgrp
)
1659 mutex_lock(&cgroup_mutex
);
1660 if (cgroup_is_removed(cgrp
)) {
1661 mutex_unlock(&cgroup_mutex
);
1667 static int cgroup_release_agent_write(struct cgroup
*cgrp
, struct cftype
*cft
,
1670 BUILD_BUG_ON(sizeof(cgrp
->root
->release_agent_path
) < PATH_MAX
);
1671 if (!cgroup_lock_live_group(cgrp
))
1673 strcpy(cgrp
->root
->release_agent_path
, buffer
);
1678 static int cgroup_release_agent_show(struct cgroup
*cgrp
, struct cftype
*cft
,
1679 struct seq_file
*seq
)
1681 if (!cgroup_lock_live_group(cgrp
))
1683 seq_puts(seq
, cgrp
->root
->release_agent_path
);
1684 seq_putc(seq
, '\n');
1689 /* A buffer size big enough for numbers or short strings */
1690 #define CGROUP_LOCAL_BUFFER_SIZE 64
1692 static ssize_t
cgroup_write_X64(struct cgroup
*cgrp
, struct cftype
*cft
,
1694 const char __user
*userbuf
,
1695 size_t nbytes
, loff_t
*unused_ppos
)
1697 char buffer
[CGROUP_LOCAL_BUFFER_SIZE
];
1703 if (nbytes
>= sizeof(buffer
))
1705 if (copy_from_user(buffer
, userbuf
, nbytes
))
1708 buffer
[nbytes
] = 0; /* nul-terminate */
1710 if (cft
->write_u64
) {
1711 u64 val
= simple_strtoull(buffer
, &end
, 0);
1714 retval
= cft
->write_u64(cgrp
, cft
, val
);
1716 s64 val
= simple_strtoll(buffer
, &end
, 0);
1719 retval
= cft
->write_s64(cgrp
, cft
, val
);
1726 static ssize_t
cgroup_write_string(struct cgroup
*cgrp
, struct cftype
*cft
,
1728 const char __user
*userbuf
,
1729 size_t nbytes
, loff_t
*unused_ppos
)
1731 char local_buffer
[CGROUP_LOCAL_BUFFER_SIZE
];
1733 size_t max_bytes
= cft
->max_write_len
;
1734 char *buffer
= local_buffer
;
1737 max_bytes
= sizeof(local_buffer
) - 1;
1738 if (nbytes
>= max_bytes
)
1740 /* Allocate a dynamic buffer if we need one */
1741 if (nbytes
>= sizeof(local_buffer
)) {
1742 buffer
= kmalloc(nbytes
+ 1, GFP_KERNEL
);
1746 if (nbytes
&& copy_from_user(buffer
, userbuf
, nbytes
)) {
1751 buffer
[nbytes
] = 0; /* nul-terminate */
1753 retval
= cft
->write_string(cgrp
, cft
, buffer
);
1757 if (buffer
!= local_buffer
)
1762 static ssize_t
cgroup_file_write(struct file
*file
, const char __user
*buf
,
1763 size_t nbytes
, loff_t
*ppos
)
1765 struct cftype
*cft
= __d_cft(file
->f_dentry
);
1766 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
1768 if (cgroup_is_removed(cgrp
))
1771 return cft
->write(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1772 if (cft
->write_u64
|| cft
->write_s64
)
1773 return cgroup_write_X64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1774 if (cft
->write_string
)
1775 return cgroup_write_string(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1777 int ret
= cft
->trigger(cgrp
, (unsigned int)cft
->private);
1778 return ret
? ret
: nbytes
;
1783 static ssize_t
cgroup_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
,
1785 char __user
*buf
, size_t nbytes
,
1788 char tmp
[CGROUP_LOCAL_BUFFER_SIZE
];
1789 u64 val
= cft
->read_u64(cgrp
, cft
);
1790 int len
= sprintf(tmp
, "%llu\n", (unsigned long long) val
);
1792 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
1795 static ssize_t
cgroup_read_s64(struct cgroup
*cgrp
, struct cftype
*cft
,
1797 char __user
*buf
, size_t nbytes
,
1800 char tmp
[CGROUP_LOCAL_BUFFER_SIZE
];
1801 s64 val
= cft
->read_s64(cgrp
, cft
);
1802 int len
= sprintf(tmp
, "%lld\n", (long long) val
);
1804 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
1807 static ssize_t
cgroup_file_read(struct file
*file
, char __user
*buf
,
1808 size_t nbytes
, loff_t
*ppos
)
1810 struct cftype
*cft
= __d_cft(file
->f_dentry
);
1811 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
1813 if (cgroup_is_removed(cgrp
))
1817 return cft
->read(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1819 return cgroup_read_u64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1821 return cgroup_read_s64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
1826 * seqfile ops/methods for returning structured data. Currently just
1827 * supports string->u64 maps, but can be extended in future.
1830 struct cgroup_seqfile_state
{
1832 struct cgroup
*cgroup
;
1835 static int cgroup_map_add(struct cgroup_map_cb
*cb
, const char *key
, u64 value
)
1837 struct seq_file
*sf
= cb
->state
;
1838 return seq_printf(sf
, "%s %llu\n", key
, (unsigned long long)value
);
1841 static int cgroup_seqfile_show(struct seq_file
*m
, void *arg
)
1843 struct cgroup_seqfile_state
*state
= m
->private;
1844 struct cftype
*cft
= state
->cft
;
1845 if (cft
->read_map
) {
1846 struct cgroup_map_cb cb
= {
1847 .fill
= cgroup_map_add
,
1850 return cft
->read_map(state
->cgroup
, cft
, &cb
);
1852 return cft
->read_seq_string(state
->cgroup
, cft
, m
);
1855 static int cgroup_seqfile_release(struct inode
*inode
, struct file
*file
)
1857 struct seq_file
*seq
= file
->private_data
;
1858 kfree(seq
->private);
1859 return single_release(inode
, file
);
1862 static struct file_operations cgroup_seqfile_operations
= {
1864 .write
= cgroup_file_write
,
1865 .llseek
= seq_lseek
,
1866 .release
= cgroup_seqfile_release
,
1869 static int cgroup_file_open(struct inode
*inode
, struct file
*file
)
1874 err
= generic_file_open(inode
, file
);
1877 cft
= __d_cft(file
->f_dentry
);
1879 if (cft
->read_map
|| cft
->read_seq_string
) {
1880 struct cgroup_seqfile_state
*state
=
1881 kzalloc(sizeof(*state
), GFP_USER
);
1885 state
->cgroup
= __d_cgrp(file
->f_dentry
->d_parent
);
1886 file
->f_op
= &cgroup_seqfile_operations
;
1887 err
= single_open(file
, cgroup_seqfile_show
, state
);
1890 } else if (cft
->open
)
1891 err
= cft
->open(inode
, file
);
1898 static int cgroup_file_release(struct inode
*inode
, struct file
*file
)
1900 struct cftype
*cft
= __d_cft(file
->f_dentry
);
1902 return cft
->release(inode
, file
);
1907 * cgroup_rename - Only allow simple rename of directories in place.
1909 static int cgroup_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
1910 struct inode
*new_dir
, struct dentry
*new_dentry
)
1912 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
))
1914 if (new_dentry
->d_inode
)
1916 if (old_dir
!= new_dir
)
1918 return simple_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
1921 static struct file_operations cgroup_file_operations
= {
1922 .read
= cgroup_file_read
,
1923 .write
= cgroup_file_write
,
1924 .llseek
= generic_file_llseek
,
1925 .open
= cgroup_file_open
,
1926 .release
= cgroup_file_release
,
1929 static const struct inode_operations cgroup_dir_inode_operations
= {
1930 .lookup
= simple_lookup
,
1931 .mkdir
= cgroup_mkdir
,
1932 .rmdir
= cgroup_rmdir
,
1933 .rename
= cgroup_rename
,
1936 static int cgroup_create_file(struct dentry
*dentry
, mode_t mode
,
1937 struct super_block
*sb
)
1939 static const struct dentry_operations cgroup_dops
= {
1940 .d_iput
= cgroup_diput
,
1943 struct inode
*inode
;
1947 if (dentry
->d_inode
)
1950 inode
= cgroup_new_inode(mode
, sb
);
1954 if (S_ISDIR(mode
)) {
1955 inode
->i_op
= &cgroup_dir_inode_operations
;
1956 inode
->i_fop
= &simple_dir_operations
;
1958 /* start off with i_nlink == 2 (for "." entry) */
1961 /* start with the directory inode held, so that we can
1962 * populate it without racing with another mkdir */
1963 mutex_lock_nested(&inode
->i_mutex
, I_MUTEX_CHILD
);
1964 } else if (S_ISREG(mode
)) {
1966 inode
->i_fop
= &cgroup_file_operations
;
1968 dentry
->d_op
= &cgroup_dops
;
1969 d_instantiate(dentry
, inode
);
1970 dget(dentry
); /* Extra count - pin the dentry in core */
1975 * cgroup_create_dir - create a directory for an object.
1976 * @cgrp: the cgroup we create the directory for. It must have a valid
1977 * ->parent field. And we are going to fill its ->dentry field.
1978 * @dentry: dentry of the new cgroup
1979 * @mode: mode to set on new directory.
1981 static int cgroup_create_dir(struct cgroup
*cgrp
, struct dentry
*dentry
,
1984 struct dentry
*parent
;
1987 parent
= cgrp
->parent
->dentry
;
1988 error
= cgroup_create_file(dentry
, S_IFDIR
| mode
, cgrp
->root
->sb
);
1990 dentry
->d_fsdata
= cgrp
;
1991 inc_nlink(parent
->d_inode
);
1992 rcu_assign_pointer(cgrp
->dentry
, dentry
);
2001 * cgroup_file_mode - deduce file mode of a control file
2002 * @cft: the control file in question
2004 * returns cft->mode if ->mode is not 0
2005 * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
2006 * returns S_IRUGO if it has only a read handler
2007 * returns S_IWUSR if it has only a write hander
2009 static mode_t
cgroup_file_mode(const struct cftype
*cft
)
2016 if (cft
->read
|| cft
->read_u64
|| cft
->read_s64
||
2017 cft
->read_map
|| cft
->read_seq_string
)
2020 if (cft
->write
|| cft
->write_u64
|| cft
->write_s64
||
2021 cft
->write_string
|| cft
->trigger
)
2027 int cgroup_add_file(struct cgroup
*cgrp
,
2028 struct cgroup_subsys
*subsys
,
2029 const struct cftype
*cft
)
2031 struct dentry
*dir
= cgrp
->dentry
;
2032 struct dentry
*dentry
;
2036 char name
[MAX_CGROUP_TYPE_NAMELEN
+ MAX_CFTYPE_NAME
+ 2] = { 0 };
2037 if (subsys
&& !test_bit(ROOT_NOPREFIX
, &cgrp
->root
->flags
)) {
2038 strcpy(name
, subsys
->name
);
2041 strcat(name
, cft
->name
);
2042 BUG_ON(!mutex_is_locked(&dir
->d_inode
->i_mutex
));
2043 dentry
= lookup_one_len(name
, dir
, strlen(name
));
2044 if (!IS_ERR(dentry
)) {
2045 mode
= cgroup_file_mode(cft
);
2046 error
= cgroup_create_file(dentry
, mode
| S_IFREG
,
2049 dentry
->d_fsdata
= (void *)cft
;
2052 error
= PTR_ERR(dentry
);
2056 int cgroup_add_files(struct cgroup
*cgrp
,
2057 struct cgroup_subsys
*subsys
,
2058 const struct cftype cft
[],
2062 for (i
= 0; i
< count
; i
++) {
2063 err
= cgroup_add_file(cgrp
, subsys
, &cft
[i
]);
2071 * cgroup_task_count - count the number of tasks in a cgroup.
2072 * @cgrp: the cgroup in question
2074 * Return the number of tasks in the cgroup.
2076 int cgroup_task_count(const struct cgroup
*cgrp
)
2079 struct cg_cgroup_link
*link
;
2081 read_lock(&css_set_lock
);
2082 list_for_each_entry(link
, &cgrp
->css_sets
, cgrp_link_list
) {
2083 count
+= atomic_read(&link
->cg
->refcount
);
2085 read_unlock(&css_set_lock
);
2090 * Advance a list_head iterator. The iterator should be positioned at
2091 * the start of a css_set
2093 static void cgroup_advance_iter(struct cgroup
*cgrp
,
2094 struct cgroup_iter
*it
)
2096 struct list_head
*l
= it
->cg_link
;
2097 struct cg_cgroup_link
*link
;
2100 /* Advance to the next non-empty css_set */
2103 if (l
== &cgrp
->css_sets
) {
2107 link
= list_entry(l
, struct cg_cgroup_link
, cgrp_link_list
);
2109 } while (list_empty(&cg
->tasks
));
2111 it
->task
= cg
->tasks
.next
;
2115 * To reduce the fork() overhead for systems that are not actually
2116 * using their cgroups capability, we don't maintain the lists running
2117 * through each css_set to its tasks until we see the list actually
2118 * used - in other words after the first call to cgroup_iter_start().
2120 * The tasklist_lock is not held here, as do_each_thread() and
2121 * while_each_thread() are protected by RCU.
2123 static void cgroup_enable_task_cg_lists(void)
2125 struct task_struct
*p
, *g
;
2126 write_lock(&css_set_lock
);
2127 use_task_css_set_links
= 1;
2128 do_each_thread(g
, p
) {
2131 * We should check if the process is exiting, otherwise
2132 * it will race with cgroup_exit() in that the list
2133 * entry won't be deleted though the process has exited.
2135 if (!(p
->flags
& PF_EXITING
) && list_empty(&p
->cg_list
))
2136 list_add(&p
->cg_list
, &p
->cgroups
->tasks
);
2138 } while_each_thread(g
, p
);
2139 write_unlock(&css_set_lock
);
2142 void cgroup_iter_start(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
2145 * The first time anyone tries to iterate across a cgroup,
2146 * we need to enable the list linking each css_set to its
2147 * tasks, and fix up all existing tasks.
2149 if (!use_task_css_set_links
)
2150 cgroup_enable_task_cg_lists();
2152 read_lock(&css_set_lock
);
2153 it
->cg_link
= &cgrp
->css_sets
;
2154 cgroup_advance_iter(cgrp
, it
);
2157 struct task_struct
*cgroup_iter_next(struct cgroup
*cgrp
,
2158 struct cgroup_iter
*it
)
2160 struct task_struct
*res
;
2161 struct list_head
*l
= it
->task
;
2162 struct cg_cgroup_link
*link
;
2164 /* If the iterator cg is NULL, we have no tasks */
2167 res
= list_entry(l
, struct task_struct
, cg_list
);
2168 /* Advance iterator to find next entry */
2170 link
= list_entry(it
->cg_link
, struct cg_cgroup_link
, cgrp_link_list
);
2171 if (l
== &link
->cg
->tasks
) {
2172 /* We reached the end of this task list - move on to
2173 * the next cg_cgroup_link */
2174 cgroup_advance_iter(cgrp
, it
);
2181 void cgroup_iter_end(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
2183 read_unlock(&css_set_lock
);
2186 static inline int started_after_time(struct task_struct
*t1
,
2187 struct timespec
*time
,
2188 struct task_struct
*t2
)
2190 int start_diff
= timespec_compare(&t1
->start_time
, time
);
2191 if (start_diff
> 0) {
2193 } else if (start_diff
< 0) {
2197 * Arbitrarily, if two processes started at the same
2198 * time, we'll say that the lower pointer value
2199 * started first. Note that t2 may have exited by now
2200 * so this may not be a valid pointer any longer, but
2201 * that's fine - it still serves to distinguish
2202 * between two tasks started (effectively) simultaneously.
2209 * This function is a callback from heap_insert() and is used to order
2211 * In this case we order the heap in descending task start time.
2213 static inline int started_after(void *p1
, void *p2
)
2215 struct task_struct
*t1
= p1
;
2216 struct task_struct
*t2
= p2
;
2217 return started_after_time(t1
, &t2
->start_time
, t2
);
2221 * cgroup_scan_tasks - iterate though all the tasks in a cgroup
2222 * @scan: struct cgroup_scanner containing arguments for the scan
2224 * Arguments include pointers to callback functions test_task() and
2226 * Iterate through all the tasks in a cgroup, calling test_task() for each,
2227 * and if it returns true, call process_task() for it also.
2228 * The test_task pointer may be NULL, meaning always true (select all tasks).
2229 * Effectively duplicates cgroup_iter_{start,next,end}()
2230 * but does not lock css_set_lock for the call to process_task().
2231 * The struct cgroup_scanner may be embedded in any structure of the caller's
2233 * It is guaranteed that process_task() will act on every task that
2234 * is a member of the cgroup for the duration of this call. This
2235 * function may or may not call process_task() for tasks that exit
2236 * or move to a different cgroup during the call, or are forked or
2237 * move into the cgroup during the call.
2239 * Note that test_task() may be called with locks held, and may in some
2240 * situations be called multiple times for the same task, so it should
2242 * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been
2243 * pre-allocated and will be used for heap operations (and its "gt" member will
2244 * be overwritten), else a temporary heap will be used (allocation of which
2245 * may cause this function to fail).
2247 int cgroup_scan_tasks(struct cgroup_scanner
*scan
)
2250 struct cgroup_iter it
;
2251 struct task_struct
*p
, *dropped
;
2252 /* Never dereference latest_task, since it's not refcounted */
2253 struct task_struct
*latest_task
= NULL
;
2254 struct ptr_heap tmp_heap
;
2255 struct ptr_heap
*heap
;
2256 struct timespec latest_time
= { 0, 0 };
2259 /* The caller supplied our heap and pre-allocated its memory */
2261 heap
->gt
= &started_after
;
2263 /* We need to allocate our own heap memory */
2265 retval
= heap_init(heap
, PAGE_SIZE
, GFP_KERNEL
, &started_after
);
2267 /* cannot allocate the heap */
2273 * Scan tasks in the cgroup, using the scanner's "test_task" callback
2274 * to determine which are of interest, and using the scanner's
2275 * "process_task" callback to process any of them that need an update.
2276 * Since we don't want to hold any locks during the task updates,
2277 * gather tasks to be processed in a heap structure.
2278 * The heap is sorted by descending task start time.
2279 * If the statically-sized heap fills up, we overflow tasks that
2280 * started later, and in future iterations only consider tasks that
2281 * started after the latest task in the previous pass. This
2282 * guarantees forward progress and that we don't miss any tasks.
2285 cgroup_iter_start(scan
->cg
, &it
);
2286 while ((p
= cgroup_iter_next(scan
->cg
, &it
))) {
2288 * Only affect tasks that qualify per the caller's callback,
2289 * if he provided one
2291 if (scan
->test_task
&& !scan
->test_task(p
, scan
))
2294 * Only process tasks that started after the last task
2297 if (!started_after_time(p
, &latest_time
, latest_task
))
2299 dropped
= heap_insert(heap
, p
);
2300 if (dropped
== NULL
) {
2302 * The new task was inserted; the heap wasn't
2306 } else if (dropped
!= p
) {
2308 * The new task was inserted, and pushed out a
2312 put_task_struct(dropped
);
2315 * Else the new task was newer than anything already in
2316 * the heap and wasn't inserted
2319 cgroup_iter_end(scan
->cg
, &it
);
2322 for (i
= 0; i
< heap
->size
; i
++) {
2323 struct task_struct
*q
= heap
->ptrs
[i
];
2325 latest_time
= q
->start_time
;
2328 /* Process the task per the caller's callback */
2329 scan
->process_task(q
, scan
);
2333 * If we had to process any tasks at all, scan again
2334 * in case some of them were in the middle of forking
2335 * children that didn't get processed.
2336 * Not the most efficient way to do it, but it avoids
2337 * having to take callback_mutex in the fork path
2341 if (heap
== &tmp_heap
)
2342 heap_free(&tmp_heap
);
2347 * Stuff for reading the 'tasks' file.
2349 * Reading this file can return large amounts of data if a cgroup has
2350 * *lots* of attached tasks. So it may need several calls to read(),
2351 * but we cannot guarantee that the information we produce is correct
2352 * unless we produce it entirely atomically.
2357 * Load into 'pidarray' up to 'npids' of the tasks using cgroup
2358 * 'cgrp'. Return actual number of pids loaded. No need to
2359 * task_lock(p) when reading out p->cgroup, since we're in an RCU
2360 * read section, so the css_set can't go away, and is
2361 * immutable after creation.
2363 static int pid_array_load(pid_t
*pidarray
, int npids
, struct cgroup
*cgrp
)
2366 struct cgroup_iter it
;
2367 struct task_struct
*tsk
;
2368 cgroup_iter_start(cgrp
, &it
);
2369 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
2370 if (unlikely(n
== npids
))
2372 pid
= task_pid_vnr(tsk
);
2374 pidarray
[n
++] = pid
;
2376 cgroup_iter_end(cgrp
, &it
);
2381 * cgroupstats_build - build and fill cgroupstats
2382 * @stats: cgroupstats to fill information into
2383 * @dentry: A dentry entry belonging to the cgroup for which stats have
2386 * Build and fill cgroupstats so that taskstats can export it to user
2389 int cgroupstats_build(struct cgroupstats
*stats
, struct dentry
*dentry
)
2392 struct cgroup
*cgrp
;
2393 struct cgroup_iter it
;
2394 struct task_struct
*tsk
;
2397 * Validate dentry by checking the superblock operations,
2398 * and make sure it's a directory.
2400 if (dentry
->d_sb
->s_op
!= &cgroup_ops
||
2401 !S_ISDIR(dentry
->d_inode
->i_mode
))
2405 cgrp
= dentry
->d_fsdata
;
2407 cgroup_iter_start(cgrp
, &it
);
2408 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
2409 switch (tsk
->state
) {
2411 stats
->nr_running
++;
2413 case TASK_INTERRUPTIBLE
:
2414 stats
->nr_sleeping
++;
2416 case TASK_UNINTERRUPTIBLE
:
2417 stats
->nr_uninterruptible
++;
2420 stats
->nr_stopped
++;
2423 if (delayacct_is_task_waiting_on_io(tsk
))
2424 stats
->nr_io_wait
++;
2428 cgroup_iter_end(cgrp
, &it
);
2435 * Cache pids for all threads in the same pid namespace that are
2436 * opening the same "tasks" file.
2438 struct cgroup_pids
{
2439 /* The node in cgrp->pids_list */
2440 struct list_head list
;
2441 /* The cgroup those pids belong to */
2442 struct cgroup
*cgrp
;
2443 /* The namepsace those pids belong to */
2444 struct pid_namespace
*ns
;
2445 /* Array of process ids in the cgroup */
2447 /* How many files are using the this tasks_pids array */
2449 /* Length of the current tasks_pids array */
2453 static int cmppid(const void *a
, const void *b
)
2455 return *(pid_t
*)a
- *(pid_t
*)b
;
2459 * seq_file methods for the "tasks" file. The seq_file position is the
2460 * next pid to display; the seq_file iterator is a pointer to the pid
2461 * in the cgroup->tasks_pids array.
2464 static void *cgroup_tasks_start(struct seq_file
*s
, loff_t
*pos
)
2467 * Initially we receive a position value that corresponds to
2468 * one more than the last pid shown (or 0 on the first call or
2469 * after a seek to the start). Use a binary-search to find the
2470 * next pid to display, if any
2472 struct cgroup_pids
*cp
= s
->private;
2473 struct cgroup
*cgrp
= cp
->cgrp
;
2474 int index
= 0, pid
= *pos
;
2477 down_read(&cgrp
->pids_mutex
);
2479 int end
= cp
->length
;
2481 while (index
< end
) {
2482 int mid
= (index
+ end
) / 2;
2483 if (cp
->tasks_pids
[mid
] == pid
) {
2486 } else if (cp
->tasks_pids
[mid
] <= pid
)
2492 /* If we're off the end of the array, we're done */
2493 if (index
>= cp
->length
)
2495 /* Update the abstract position to be the actual pid that we found */
2496 iter
= cp
->tasks_pids
+ index
;
2501 static void cgroup_tasks_stop(struct seq_file
*s
, void *v
)
2503 struct cgroup_pids
*cp
= s
->private;
2504 struct cgroup
*cgrp
= cp
->cgrp
;
2505 up_read(&cgrp
->pids_mutex
);
2508 static void *cgroup_tasks_next(struct seq_file
*s
, void *v
, loff_t
*pos
)
2510 struct cgroup_pids
*cp
= s
->private;
2512 int *end
= cp
->tasks_pids
+ cp
->length
;
2515 * Advance to the next pid in the array. If this goes off the
2527 static int cgroup_tasks_show(struct seq_file
*s
, void *v
)
2529 return seq_printf(s
, "%d\n", *(int *)v
);
2532 static const struct seq_operations cgroup_tasks_seq_operations
= {
2533 .start
= cgroup_tasks_start
,
2534 .stop
= cgroup_tasks_stop
,
2535 .next
= cgroup_tasks_next
,
2536 .show
= cgroup_tasks_show
,
2539 static void release_cgroup_pid_array(struct cgroup_pids
*cp
)
2541 struct cgroup
*cgrp
= cp
->cgrp
;
2543 down_write(&cgrp
->pids_mutex
);
2544 BUG_ON(!cp
->use_count
);
2545 if (!--cp
->use_count
) {
2546 list_del(&cp
->list
);
2548 kfree(cp
->tasks_pids
);
2551 up_write(&cgrp
->pids_mutex
);
2554 static int cgroup_tasks_release(struct inode
*inode
, struct file
*file
)
2556 struct seq_file
*seq
;
2557 struct cgroup_pids
*cp
;
2559 if (!(file
->f_mode
& FMODE_READ
))
2562 seq
= file
->private_data
;
2565 release_cgroup_pid_array(cp
);
2566 return seq_release(inode
, file
);
2569 static struct file_operations cgroup_tasks_operations
= {
2571 .llseek
= seq_lseek
,
2572 .write
= cgroup_file_write
,
2573 .release
= cgroup_tasks_release
,
2577 * Handle an open on 'tasks' file. Prepare an array containing the
2578 * process id's of tasks currently attached to the cgroup being opened.
2581 static int cgroup_tasks_open(struct inode
*unused
, struct file
*file
)
2583 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
2584 struct pid_namespace
*ns
= current
->nsproxy
->pid_ns
;
2585 struct cgroup_pids
*cp
;
2590 /* Nothing to do for write-only files */
2591 if (!(file
->f_mode
& FMODE_READ
))
2595 * If cgroup gets more users after we read count, we won't have
2596 * enough space - tough. This race is indistinguishable to the
2597 * caller from the case that the additional cgroup users didn't
2598 * show up until sometime later on.
2600 npids
= cgroup_task_count(cgrp
);
2601 pidarray
= kmalloc(npids
* sizeof(pid_t
), GFP_KERNEL
);
2604 npids
= pid_array_load(pidarray
, npids
, cgrp
);
2605 sort(pidarray
, npids
, sizeof(pid_t
), cmppid
, NULL
);
2608 * Store the array in the cgroup, freeing the old
2609 * array if necessary
2611 down_write(&cgrp
->pids_mutex
);
2613 list_for_each_entry(cp
, &cgrp
->pids_list
, list
) {
2618 cp
= kzalloc(sizeof(*cp
), GFP_KERNEL
);
2620 up_write(&cgrp
->pids_mutex
);
2627 list_add(&cp
->list
, &cgrp
->pids_list
);
2629 kfree(cp
->tasks_pids
);
2630 cp
->tasks_pids
= pidarray
;
2633 up_write(&cgrp
->pids_mutex
);
2635 file
->f_op
= &cgroup_tasks_operations
;
2637 retval
= seq_open(file
, &cgroup_tasks_seq_operations
);
2639 release_cgroup_pid_array(cp
);
2642 ((struct seq_file
*)file
->private_data
)->private = cp
;
2646 static u64
cgroup_read_notify_on_release(struct cgroup
*cgrp
,
2649 return notify_on_release(cgrp
);
2652 static int cgroup_write_notify_on_release(struct cgroup
*cgrp
,
2656 clear_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
2658 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
2660 clear_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
2665 * for the common functions, 'private' gives the type of file
2667 static struct cftype files
[] = {
2670 .open
= cgroup_tasks_open
,
2671 .write_u64
= cgroup_tasks_write
,
2672 .release
= cgroup_tasks_release
,
2673 .private = FILE_TASKLIST
,
2674 .mode
= S_IRUGO
| S_IWUSR
,
2678 .name
= "notify_on_release",
2679 .read_u64
= cgroup_read_notify_on_release
,
2680 .write_u64
= cgroup_write_notify_on_release
,
2681 .private = FILE_NOTIFY_ON_RELEASE
,
2685 static struct cftype cft_release_agent
= {
2686 .name
= "release_agent",
2687 .read_seq_string
= cgroup_release_agent_show
,
2688 .write_string
= cgroup_release_agent_write
,
2689 .max_write_len
= PATH_MAX
,
2690 .private = FILE_RELEASE_AGENT
,
2693 static int cgroup_populate_dir(struct cgroup
*cgrp
)
2696 struct cgroup_subsys
*ss
;
2698 /* First clear out any existing files */
2699 cgroup_clear_directory(cgrp
->dentry
);
2701 err
= cgroup_add_files(cgrp
, NULL
, files
, ARRAY_SIZE(files
));
2705 if (cgrp
== cgrp
->top_cgroup
) {
2706 if ((err
= cgroup_add_file(cgrp
, NULL
, &cft_release_agent
)) < 0)
2710 for_each_subsys(cgrp
->root
, ss
) {
2711 if (ss
->populate
&& (err
= ss
->populate(ss
, cgrp
)) < 0)
2714 /* This cgroup is ready now */
2715 for_each_subsys(cgrp
->root
, ss
) {
2716 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
2718 * Update id->css pointer and make this css visible from
2719 * CSS ID functions. This pointer will be dereferened
2720 * from RCU-read-side without locks.
2723 rcu_assign_pointer(css
->id
->css
, css
);
2729 static void init_cgroup_css(struct cgroup_subsys_state
*css
,
2730 struct cgroup_subsys
*ss
,
2731 struct cgroup
*cgrp
)
2734 atomic_set(&css
->refcnt
, 1);
2737 if (cgrp
== dummytop
)
2738 set_bit(CSS_ROOT
, &css
->flags
);
2739 BUG_ON(cgrp
->subsys
[ss
->subsys_id
]);
2740 cgrp
->subsys
[ss
->subsys_id
] = css
;
2743 static void cgroup_lock_hierarchy(struct cgroupfs_root
*root
)
2745 /* We need to take each hierarchy_mutex in a consistent order */
2748 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2749 struct cgroup_subsys
*ss
= subsys
[i
];
2750 if (ss
->root
== root
)
2751 mutex_lock(&ss
->hierarchy_mutex
);
2755 static void cgroup_unlock_hierarchy(struct cgroupfs_root
*root
)
2759 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2760 struct cgroup_subsys
*ss
= subsys
[i
];
2761 if (ss
->root
== root
)
2762 mutex_unlock(&ss
->hierarchy_mutex
);
2767 * cgroup_create - create a cgroup
2768 * @parent: cgroup that will be parent of the new cgroup
2769 * @dentry: dentry of the new cgroup
2770 * @mode: mode to set on new inode
2772 * Must be called with the mutex on the parent inode held
2774 static long cgroup_create(struct cgroup
*parent
, struct dentry
*dentry
,
2777 struct cgroup
*cgrp
;
2778 struct cgroupfs_root
*root
= parent
->root
;
2780 struct cgroup_subsys
*ss
;
2781 struct super_block
*sb
= root
->sb
;
2783 cgrp
= kzalloc(sizeof(*cgrp
), GFP_KERNEL
);
2787 /* Grab a reference on the superblock so the hierarchy doesn't
2788 * get deleted on unmount if there are child cgroups. This
2789 * can be done outside cgroup_mutex, since the sb can't
2790 * disappear while someone has an open control file on the
2792 atomic_inc(&sb
->s_active
);
2794 mutex_lock(&cgroup_mutex
);
2796 init_cgroup_housekeeping(cgrp
);
2798 cgrp
->parent
= parent
;
2799 cgrp
->root
= parent
->root
;
2800 cgrp
->top_cgroup
= parent
->top_cgroup
;
2802 if (notify_on_release(parent
))
2803 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
2805 for_each_subsys(root
, ss
) {
2806 struct cgroup_subsys_state
*css
= ss
->create(ss
, cgrp
);
2811 init_cgroup_css(css
, ss
, cgrp
);
2813 if (alloc_css_id(ss
, parent
, cgrp
))
2815 /* At error, ->destroy() callback has to free assigned ID. */
2818 cgroup_lock_hierarchy(root
);
2819 list_add(&cgrp
->sibling
, &cgrp
->parent
->children
);
2820 cgroup_unlock_hierarchy(root
);
2821 root
->number_of_cgroups
++;
2823 err
= cgroup_create_dir(cgrp
, dentry
, mode
);
2827 /* The cgroup directory was pre-locked for us */
2828 BUG_ON(!mutex_is_locked(&cgrp
->dentry
->d_inode
->i_mutex
));
2830 err
= cgroup_populate_dir(cgrp
);
2831 /* If err < 0, we have a half-filled directory - oh well ;) */
2833 mutex_unlock(&cgroup_mutex
);
2834 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
2840 cgroup_lock_hierarchy(root
);
2841 list_del(&cgrp
->sibling
);
2842 cgroup_unlock_hierarchy(root
);
2843 root
->number_of_cgroups
--;
2847 for_each_subsys(root
, ss
) {
2848 if (cgrp
->subsys
[ss
->subsys_id
])
2849 ss
->destroy(ss
, cgrp
);
2852 mutex_unlock(&cgroup_mutex
);
2854 /* Release the reference count that we took on the superblock */
2855 deactivate_super(sb
);
2861 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
2863 struct cgroup
*c_parent
= dentry
->d_parent
->d_fsdata
;
2865 /* the vfs holds inode->i_mutex already */
2866 return cgroup_create(c_parent
, dentry
, mode
| S_IFDIR
);
2869 static int cgroup_has_css_refs(struct cgroup
*cgrp
)
2871 /* Check the reference count on each subsystem. Since we
2872 * already established that there are no tasks in the
2873 * cgroup, if the css refcount is also 1, then there should
2874 * be no outstanding references, so the subsystem is safe to
2875 * destroy. We scan across all subsystems rather than using
2876 * the per-hierarchy linked list of mounted subsystems since
2877 * we can be called via check_for_release() with no
2878 * synchronization other than RCU, and the subsystem linked
2879 * list isn't RCU-safe */
2881 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
2882 struct cgroup_subsys
*ss
= subsys
[i
];
2883 struct cgroup_subsys_state
*css
;
2884 /* Skip subsystems not in this hierarchy */
2885 if (ss
->root
!= cgrp
->root
)
2887 css
= cgrp
->subsys
[ss
->subsys_id
];
2888 /* When called from check_for_release() it's possible
2889 * that by this point the cgroup has been removed
2890 * and the css deleted. But a false-positive doesn't
2891 * matter, since it can only happen if the cgroup
2892 * has been deleted and hence no longer needs the
2893 * release agent to be called anyway. */
2894 if (css
&& (atomic_read(&css
->refcnt
) > 1))
2901 * Atomically mark all (or else none) of the cgroup's CSS objects as
2902 * CSS_REMOVED. Return true on success, or false if the cgroup has
2903 * busy subsystems. Call with cgroup_mutex held
2906 static int cgroup_clear_css_refs(struct cgroup
*cgrp
)
2908 struct cgroup_subsys
*ss
;
2909 unsigned long flags
;
2910 bool failed
= false;
2911 local_irq_save(flags
);
2912 for_each_subsys(cgrp
->root
, ss
) {
2913 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
2916 /* We can only remove a CSS with a refcnt==1 */
2917 refcnt
= atomic_read(&css
->refcnt
);
2924 * Drop the refcnt to 0 while we check other
2925 * subsystems. This will cause any racing
2926 * css_tryget() to spin until we set the
2927 * CSS_REMOVED bits or abort
2929 if (atomic_cmpxchg(&css
->refcnt
, refcnt
, 0) == refcnt
)
2935 for_each_subsys(cgrp
->root
, ss
) {
2936 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
2939 * Restore old refcnt if we previously managed
2940 * to clear it from 1 to 0
2942 if (!atomic_read(&css
->refcnt
))
2943 atomic_set(&css
->refcnt
, 1);
2945 /* Commit the fact that the CSS is removed */
2946 set_bit(CSS_REMOVED
, &css
->flags
);
2949 local_irq_restore(flags
);
2953 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
)
2955 struct cgroup
*cgrp
= dentry
->d_fsdata
;
2957 struct cgroup
*parent
;
2961 /* the vfs holds both inode->i_mutex already */
2963 mutex_lock(&cgroup_mutex
);
2964 if (atomic_read(&cgrp
->count
) != 0) {
2965 mutex_unlock(&cgroup_mutex
);
2968 if (!list_empty(&cgrp
->children
)) {
2969 mutex_unlock(&cgroup_mutex
);
2972 mutex_unlock(&cgroup_mutex
);
2975 * In general, subsystem has no css->refcnt after pre_destroy(). But
2976 * in racy cases, subsystem may have to get css->refcnt after
2977 * pre_destroy() and it makes rmdir return with -EBUSY. This sometimes
2978 * make rmdir return -EBUSY too often. To avoid that, we use waitqueue
2979 * for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir
2980 * and subsystem's reference count handling. Please see css_get/put
2981 * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation.
2983 set_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
);
2986 * Call pre_destroy handlers of subsys. Notify subsystems
2987 * that rmdir() request comes.
2989 ret
= cgroup_call_pre_destroy(cgrp
);
2991 clear_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
);
2995 mutex_lock(&cgroup_mutex
);
2996 parent
= cgrp
->parent
;
2997 if (atomic_read(&cgrp
->count
) || !list_empty(&cgrp
->children
)) {
2998 clear_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
);
2999 mutex_unlock(&cgroup_mutex
);
3002 prepare_to_wait(&cgroup_rmdir_waitq
, &wait
, TASK_INTERRUPTIBLE
);
3003 if (!cgroup_clear_css_refs(cgrp
)) {
3004 mutex_unlock(&cgroup_mutex
);
3006 * Because someone may call cgroup_wakeup_rmdir_waiter() before
3007 * prepare_to_wait(), we need to check this flag.
3009 if (test_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
))
3011 finish_wait(&cgroup_rmdir_waitq
, &wait
);
3012 clear_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
);
3013 if (signal_pending(current
))
3017 /* NO css_tryget() can success after here. */
3018 finish_wait(&cgroup_rmdir_waitq
, &wait
);
3019 clear_bit(CGRP_WAIT_ON_RMDIR
, &cgrp
->flags
);
3021 spin_lock(&release_list_lock
);
3022 set_bit(CGRP_REMOVED
, &cgrp
->flags
);
3023 if (!list_empty(&cgrp
->release_list
))
3024 list_del(&cgrp
->release_list
);
3025 spin_unlock(&release_list_lock
);
3027 cgroup_lock_hierarchy(cgrp
->root
);
3028 /* delete this cgroup from parent->children */
3029 list_del(&cgrp
->sibling
);
3030 cgroup_unlock_hierarchy(cgrp
->root
);
3032 spin_lock(&cgrp
->dentry
->d_lock
);
3033 d
= dget(cgrp
->dentry
);
3034 spin_unlock(&d
->d_lock
);
3036 cgroup_d_remove_dir(d
);
3039 set_bit(CGRP_RELEASABLE
, &parent
->flags
);
3040 check_for_release(parent
);
3042 mutex_unlock(&cgroup_mutex
);
3046 static void __init
cgroup_init_subsys(struct cgroup_subsys
*ss
)
3048 struct cgroup_subsys_state
*css
;
3050 printk(KERN_INFO
"Initializing cgroup subsys %s\n", ss
->name
);
3052 /* Create the top cgroup state for this subsystem */
3053 list_add(&ss
->sibling
, &rootnode
.subsys_list
);
3054 ss
->root
= &rootnode
;
3055 css
= ss
->create(ss
, dummytop
);
3056 /* We don't handle early failures gracefully */
3057 BUG_ON(IS_ERR(css
));
3058 init_cgroup_css(css
, ss
, dummytop
);
3060 /* Update the init_css_set to contain a subsys
3061 * pointer to this state - since the subsystem is
3062 * newly registered, all tasks and hence the
3063 * init_css_set is in the subsystem's top cgroup. */
3064 init_css_set
.subsys
[ss
->subsys_id
] = dummytop
->subsys
[ss
->subsys_id
];
3066 need_forkexit_callback
|= ss
->fork
|| ss
->exit
;
3068 /* At system boot, before all subsystems have been
3069 * registered, no tasks have been forked, so we don't
3070 * need to invoke fork callbacks here. */
3071 BUG_ON(!list_empty(&init_task
.tasks
));
3073 mutex_init(&ss
->hierarchy_mutex
);
3074 lockdep_set_class(&ss
->hierarchy_mutex
, &ss
->subsys_key
);
3079 * cgroup_init_early - cgroup initialization at system boot
3081 * Initialize cgroups at system boot, and initialize any
3082 * subsystems that request early init.
3084 int __init
cgroup_init_early(void)
3087 atomic_set(&init_css_set
.refcount
, 1);
3088 INIT_LIST_HEAD(&init_css_set
.cg_links
);
3089 INIT_LIST_HEAD(&init_css_set
.tasks
);
3090 INIT_HLIST_NODE(&init_css_set
.hlist
);
3092 init_cgroup_root(&rootnode
);
3094 init_task
.cgroups
= &init_css_set
;
3096 init_css_set_link
.cg
= &init_css_set
;
3097 init_css_set_link
.cgrp
= dummytop
;
3098 list_add(&init_css_set_link
.cgrp_link_list
,
3099 &rootnode
.top_cgroup
.css_sets
);
3100 list_add(&init_css_set_link
.cg_link_list
,
3101 &init_css_set
.cg_links
);
3103 for (i
= 0; i
< CSS_SET_TABLE_SIZE
; i
++)
3104 INIT_HLIST_HEAD(&css_set_table
[i
]);
3106 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
3107 struct cgroup_subsys
*ss
= subsys
[i
];
3110 BUG_ON(strlen(ss
->name
) > MAX_CGROUP_TYPE_NAMELEN
);
3111 BUG_ON(!ss
->create
);
3112 BUG_ON(!ss
->destroy
);
3113 if (ss
->subsys_id
!= i
) {
3114 printk(KERN_ERR
"cgroup: Subsys %s id == %d\n",
3115 ss
->name
, ss
->subsys_id
);
3120 cgroup_init_subsys(ss
);
3126 * cgroup_init - cgroup initialization
3128 * Register cgroup filesystem and /proc file, and initialize
3129 * any subsystems that didn't request early init.
3131 int __init
cgroup_init(void)
3135 struct hlist_head
*hhead
;
3137 err
= bdi_init(&cgroup_backing_dev_info
);
3141 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
3142 struct cgroup_subsys
*ss
= subsys
[i
];
3143 if (!ss
->early_init
)
3144 cgroup_init_subsys(ss
);
3146 cgroup_subsys_init_idr(ss
);
3149 /* Add init_css_set to the hash table */
3150 hhead
= css_set_hash(init_css_set
.subsys
);
3151 hlist_add_head(&init_css_set
.hlist
, hhead
);
3152 BUG_ON(!init_root_id(&rootnode
));
3153 err
= register_filesystem(&cgroup_fs_type
);
3157 proc_create("cgroups", 0, NULL
, &proc_cgroupstats_operations
);
3161 bdi_destroy(&cgroup_backing_dev_info
);
3167 * proc_cgroup_show()
3168 * - Print task's cgroup paths into seq_file, one line for each hierarchy
3169 * - Used for /proc/<pid>/cgroup.
3170 * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
3171 * doesn't really matter if tsk->cgroup changes after we read it,
3172 * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
3173 * anyway. No need to check that tsk->cgroup != NULL, thanks to
3174 * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
3175 * cgroup to top_cgroup.
3178 /* TODO: Use a proper seq_file iterator */
3179 static int proc_cgroup_show(struct seq_file
*m
, void *v
)
3182 struct task_struct
*tsk
;
3185 struct cgroupfs_root
*root
;
3188 buf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
3194 tsk
= get_pid_task(pid
, PIDTYPE_PID
);
3200 mutex_lock(&cgroup_mutex
);
3202 for_each_active_root(root
) {
3203 struct cgroup_subsys
*ss
;
3204 struct cgroup
*cgrp
;
3207 seq_printf(m
, "%d:", root
->hierarchy_id
);
3208 for_each_subsys(root
, ss
)
3209 seq_printf(m
, "%s%s", count
++ ? "," : "", ss
->name
);
3210 if (strlen(root
->name
))
3211 seq_printf(m
, "%sname=%s", count
? "," : "",
3214 cgrp
= task_cgroup_from_root(tsk
, root
);
3215 retval
= cgroup_path(cgrp
, buf
, PAGE_SIZE
);
3223 mutex_unlock(&cgroup_mutex
);
3224 put_task_struct(tsk
);
3231 static int cgroup_open(struct inode
*inode
, struct file
*file
)
3233 struct pid
*pid
= PROC_I(inode
)->pid
;
3234 return single_open(file
, proc_cgroup_show
, pid
);
3237 struct file_operations proc_cgroup_operations
= {
3238 .open
= cgroup_open
,
3240 .llseek
= seq_lseek
,
3241 .release
= single_release
,
3244 /* Display information about each subsystem and each hierarchy */
3245 static int proc_cgroupstats_show(struct seq_file
*m
, void *v
)
3249 seq_puts(m
, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
3250 mutex_lock(&cgroup_mutex
);
3251 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
3252 struct cgroup_subsys
*ss
= subsys
[i
];
3253 seq_printf(m
, "%s\t%d\t%d\t%d\n",
3254 ss
->name
, ss
->root
->hierarchy_id
,
3255 ss
->root
->number_of_cgroups
, !ss
->disabled
);
3257 mutex_unlock(&cgroup_mutex
);
3261 static int cgroupstats_open(struct inode
*inode
, struct file
*file
)
3263 return single_open(file
, proc_cgroupstats_show
, NULL
);
3266 static struct file_operations proc_cgroupstats_operations
= {
3267 .open
= cgroupstats_open
,
3269 .llseek
= seq_lseek
,
3270 .release
= single_release
,
3274 * cgroup_fork - attach newly forked task to its parents cgroup.
3275 * @child: pointer to task_struct of forking parent process.
3277 * Description: A task inherits its parent's cgroup at fork().
3279 * A pointer to the shared css_set was automatically copied in
3280 * fork.c by dup_task_struct(). However, we ignore that copy, since
3281 * it was not made under the protection of RCU or cgroup_mutex, so
3282 * might no longer be a valid cgroup pointer. cgroup_attach_task() might
3283 * have already changed current->cgroups, allowing the previously
3284 * referenced cgroup group to be removed and freed.
3286 * At the point that cgroup_fork() is called, 'current' is the parent
3287 * task, and the passed argument 'child' points to the child task.
3289 void cgroup_fork(struct task_struct
*child
)
3292 child
->cgroups
= current
->cgroups
;
3293 get_css_set(child
->cgroups
);
3294 task_unlock(current
);
3295 INIT_LIST_HEAD(&child
->cg_list
);
3299 * cgroup_fork_callbacks - run fork callbacks
3300 * @child: the new task
3302 * Called on a new task very soon before adding it to the
3303 * tasklist. No need to take any locks since no-one can
3304 * be operating on this task.
3306 void cgroup_fork_callbacks(struct task_struct
*child
)
3308 if (need_forkexit_callback
) {
3310 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
3311 struct cgroup_subsys
*ss
= subsys
[i
];
3313 ss
->fork(ss
, child
);
3319 * cgroup_post_fork - called on a new task after adding it to the task list
3320 * @child: the task in question
3322 * Adds the task to the list running through its css_set if necessary.
3323 * Has to be after the task is visible on the task list in case we race
3324 * with the first call to cgroup_iter_start() - to guarantee that the
3325 * new task ends up on its list.
3327 void cgroup_post_fork(struct task_struct
*child
)
3329 if (use_task_css_set_links
) {
3330 write_lock(&css_set_lock
);
3332 if (list_empty(&child
->cg_list
))
3333 list_add(&child
->cg_list
, &child
->cgroups
->tasks
);
3335 write_unlock(&css_set_lock
);
3339 * cgroup_exit - detach cgroup from exiting task
3340 * @tsk: pointer to task_struct of exiting process
3341 * @run_callback: run exit callbacks?
3343 * Description: Detach cgroup from @tsk and release it.
3345 * Note that cgroups marked notify_on_release force every task in
3346 * them to take the global cgroup_mutex mutex when exiting.
3347 * This could impact scaling on very large systems. Be reluctant to
3348 * use notify_on_release cgroups where very high task exit scaling
3349 * is required on large systems.
3351 * the_top_cgroup_hack:
3353 * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
3355 * We call cgroup_exit() while the task is still competent to
3356 * handle notify_on_release(), then leave the task attached to the
3357 * root cgroup in each hierarchy for the remainder of its exit.
3359 * To do this properly, we would increment the reference count on
3360 * top_cgroup, and near the very end of the kernel/exit.c do_exit()
3361 * code we would add a second cgroup function call, to drop that
3362 * reference. This would just create an unnecessary hot spot on
3363 * the top_cgroup reference count, to no avail.
3365 * Normally, holding a reference to a cgroup without bumping its
3366 * count is unsafe. The cgroup could go away, or someone could
3367 * attach us to a different cgroup, decrementing the count on
3368 * the first cgroup that we never incremented. But in this case,
3369 * top_cgroup isn't going away, and either task has PF_EXITING set,
3370 * which wards off any cgroup_attach_task() attempts, or task is a failed
3371 * fork, never visible to cgroup_attach_task.
3373 void cgroup_exit(struct task_struct
*tsk
, int run_callbacks
)
3378 if (run_callbacks
&& need_forkexit_callback
) {
3379 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
3380 struct cgroup_subsys
*ss
= subsys
[i
];
3387 * Unlink from the css_set task list if necessary.
3388 * Optimistically check cg_list before taking
3391 if (!list_empty(&tsk
->cg_list
)) {
3392 write_lock(&css_set_lock
);
3393 if (!list_empty(&tsk
->cg_list
))
3394 list_del(&tsk
->cg_list
);
3395 write_unlock(&css_set_lock
);
3398 /* Reassign the task to the init_css_set. */
3401 tsk
->cgroups
= &init_css_set
;
3404 put_css_set_taskexit(cg
);
3408 * cgroup_clone - clone the cgroup the given subsystem is attached to
3409 * @tsk: the task to be moved
3410 * @subsys: the given subsystem
3411 * @nodename: the name for the new cgroup
3413 * Duplicate the current cgroup in the hierarchy that the given
3414 * subsystem is attached to, and move this task into the new
3417 int cgroup_clone(struct task_struct
*tsk
, struct cgroup_subsys
*subsys
,
3420 struct dentry
*dentry
;
3422 struct cgroup
*parent
, *child
;
3423 struct inode
*inode
;
3425 struct cgroupfs_root
*root
;
3426 struct cgroup_subsys
*ss
;
3428 /* We shouldn't be called by an unregistered subsystem */
3429 BUG_ON(!subsys
->active
);
3431 /* First figure out what hierarchy and cgroup we're dealing
3432 * with, and pin them so we can drop cgroup_mutex */
3433 mutex_lock(&cgroup_mutex
);
3435 root
= subsys
->root
;
3436 if (root
== &rootnode
) {
3437 mutex_unlock(&cgroup_mutex
);
3441 /* Pin the hierarchy */
3442 if (!atomic_inc_not_zero(&root
->sb
->s_active
)) {
3443 /* We race with the final deactivate_super() */
3444 mutex_unlock(&cgroup_mutex
);
3448 /* Keep the cgroup alive */
3450 parent
= task_cgroup(tsk
, subsys
->subsys_id
);
3455 mutex_unlock(&cgroup_mutex
);
3457 /* Now do the VFS work to create a cgroup */
3458 inode
= parent
->dentry
->d_inode
;
3460 /* Hold the parent directory mutex across this operation to
3461 * stop anyone else deleting the new cgroup */
3462 mutex_lock(&inode
->i_mutex
);
3463 dentry
= lookup_one_len(nodename
, parent
->dentry
, strlen(nodename
));
3464 if (IS_ERR(dentry
)) {
3466 "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename
,
3468 ret
= PTR_ERR(dentry
);
3472 /* Create the cgroup directory, which also creates the cgroup */
3473 ret
= vfs_mkdir(inode
, dentry
, 0755);
3474 child
= __d_cgrp(dentry
);
3478 "Failed to create cgroup %s: %d\n", nodename
,
3483 /* The cgroup now exists. Retake cgroup_mutex and check
3484 * that we're still in the same state that we thought we
3486 mutex_lock(&cgroup_mutex
);
3487 if ((root
!= subsys
->root
) ||
3488 (parent
!= task_cgroup(tsk
, subsys
->subsys_id
))) {
3489 /* Aargh, we raced ... */
3490 mutex_unlock(&inode
->i_mutex
);
3493 deactivate_super(root
->sb
);
3494 /* The cgroup is still accessible in the VFS, but
3495 * we're not going to try to rmdir() it at this
3498 "Race in cgroup_clone() - leaking cgroup %s\n",
3503 /* do any required auto-setup */
3504 for_each_subsys(root
, ss
) {
3506 ss
->post_clone(ss
, child
);
3509 /* All seems fine. Finish by moving the task into the new cgroup */
3510 ret
= cgroup_attach_task(child
, tsk
);
3511 mutex_unlock(&cgroup_mutex
);
3514 mutex_unlock(&inode
->i_mutex
);
3516 mutex_lock(&cgroup_mutex
);
3518 mutex_unlock(&cgroup_mutex
);
3519 deactivate_super(root
->sb
);
3524 * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp
3525 * @cgrp: the cgroup in question
3526 * @task: the task in question
3528 * See if @cgrp is a descendant of @task's cgroup in the appropriate
3531 * If we are sending in dummytop, then presumably we are creating
3532 * the top cgroup in the subsystem.
3534 * Called only by the ns (nsproxy) cgroup.
3536 int cgroup_is_descendant(const struct cgroup
*cgrp
, struct task_struct
*task
)
3539 struct cgroup
*target
;
3541 if (cgrp
== dummytop
)
3544 target
= task_cgroup_from_root(task
, cgrp
->root
);
3545 while (cgrp
!= target
&& cgrp
!= cgrp
->top_cgroup
)
3546 cgrp
= cgrp
->parent
;
3547 ret
= (cgrp
== target
);
3551 static void check_for_release(struct cgroup
*cgrp
)
3553 /* All of these checks rely on RCU to keep the cgroup
3554 * structure alive */
3555 if (cgroup_is_releasable(cgrp
) && !atomic_read(&cgrp
->count
)
3556 && list_empty(&cgrp
->children
) && !cgroup_has_css_refs(cgrp
)) {
3557 /* Control Group is currently removeable. If it's not
3558 * already queued for a userspace notification, queue
3560 int need_schedule_work
= 0;
3561 spin_lock(&release_list_lock
);
3562 if (!cgroup_is_removed(cgrp
) &&
3563 list_empty(&cgrp
->release_list
)) {
3564 list_add(&cgrp
->release_list
, &release_list
);
3565 need_schedule_work
= 1;
3567 spin_unlock(&release_list_lock
);
3568 if (need_schedule_work
)
3569 schedule_work(&release_agent_work
);
3573 void __css_put(struct cgroup_subsys_state
*css
)
3575 struct cgroup
*cgrp
= css
->cgroup
;
3577 if (atomic_dec_return(&css
->refcnt
) == 1) {
3578 if (notify_on_release(cgrp
)) {
3579 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
3580 check_for_release(cgrp
);
3582 cgroup_wakeup_rmdir_waiter(cgrp
);
3588 * Notify userspace when a cgroup is released, by running the
3589 * configured release agent with the name of the cgroup (path
3590 * relative to the root of cgroup file system) as the argument.
3592 * Most likely, this user command will try to rmdir this cgroup.
3594 * This races with the possibility that some other task will be
3595 * attached to this cgroup before it is removed, or that some other
3596 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
3597 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
3598 * unused, and this cgroup will be reprieved from its death sentence,
3599 * to continue to serve a useful existence. Next time it's released,
3600 * we will get notified again, if it still has 'notify_on_release' set.
3602 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
3603 * means only wait until the task is successfully execve()'d. The
3604 * separate release agent task is forked by call_usermodehelper(),
3605 * then control in this thread returns here, without waiting for the
3606 * release agent task. We don't bother to wait because the caller of
3607 * this routine has no use for the exit status of the release agent
3608 * task, so no sense holding our caller up for that.
3610 static void cgroup_release_agent(struct work_struct
*work
)
3612 BUG_ON(work
!= &release_agent_work
);
3613 mutex_lock(&cgroup_mutex
);
3614 spin_lock(&release_list_lock
);
3615 while (!list_empty(&release_list
)) {
3616 char *argv
[3], *envp
[3];
3618 char *pathbuf
= NULL
, *agentbuf
= NULL
;
3619 struct cgroup
*cgrp
= list_entry(release_list
.next
,
3622 list_del_init(&cgrp
->release_list
);
3623 spin_unlock(&release_list_lock
);
3624 pathbuf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
3627 if (cgroup_path(cgrp
, pathbuf
, PAGE_SIZE
) < 0)
3629 agentbuf
= kstrdup(cgrp
->root
->release_agent_path
, GFP_KERNEL
);
3634 argv
[i
++] = agentbuf
;
3635 argv
[i
++] = pathbuf
;
3639 /* minimal command environment */
3640 envp
[i
++] = "HOME=/";
3641 envp
[i
++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
3644 /* Drop the lock while we invoke the usermode helper,
3645 * since the exec could involve hitting disk and hence
3646 * be a slow process */
3647 mutex_unlock(&cgroup_mutex
);
3648 call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_EXEC
);
3649 mutex_lock(&cgroup_mutex
);
3653 spin_lock(&release_list_lock
);
3655 spin_unlock(&release_list_lock
);
3656 mutex_unlock(&cgroup_mutex
);
3659 static int __init
cgroup_disable(char *str
)
3664 while ((token
= strsep(&str
, ",")) != NULL
) {
3668 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
3669 struct cgroup_subsys
*ss
= subsys
[i
];
3671 if (!strcmp(token
, ss
->name
)) {
3673 printk(KERN_INFO
"Disabling %s control group"
3674 " subsystem\n", ss
->name
);
3681 __setup("cgroup_disable=", cgroup_disable
);
3684 * Functons for CSS ID.
3688 *To get ID other than 0, this should be called when !cgroup_is_removed().
3690 unsigned short css_id(struct cgroup_subsys_state
*css
)
3692 struct css_id
*cssid
= rcu_dereference(css
->id
);
3699 unsigned short css_depth(struct cgroup_subsys_state
*css
)
3701 struct css_id
*cssid
= rcu_dereference(css
->id
);
3704 return cssid
->depth
;
3708 bool css_is_ancestor(struct cgroup_subsys_state
*child
,
3709 const struct cgroup_subsys_state
*root
)
3711 struct css_id
*child_id
= rcu_dereference(child
->id
);
3712 struct css_id
*root_id
= rcu_dereference(root
->id
);
3714 if (!child_id
|| !root_id
|| (child_id
->depth
< root_id
->depth
))
3716 return child_id
->stack
[root_id
->depth
] == root_id
->id
;
3719 static void __free_css_id_cb(struct rcu_head
*head
)
3723 id
= container_of(head
, struct css_id
, rcu_head
);
3727 void free_css_id(struct cgroup_subsys
*ss
, struct cgroup_subsys_state
*css
)
3729 struct css_id
*id
= css
->id
;
3730 /* When this is called before css_id initialization, id can be NULL */
3734 BUG_ON(!ss
->use_id
);
3736 rcu_assign_pointer(id
->css
, NULL
);
3737 rcu_assign_pointer(css
->id
, NULL
);
3738 spin_lock(&ss
->id_lock
);
3739 idr_remove(&ss
->idr
, id
->id
);
3740 spin_unlock(&ss
->id_lock
);
3741 call_rcu(&id
->rcu_head
, __free_css_id_cb
);
3745 * This is called by init or create(). Then, calls to this function are
3746 * always serialized (By cgroup_mutex() at create()).
3749 static struct css_id
*get_new_cssid(struct cgroup_subsys
*ss
, int depth
)
3751 struct css_id
*newid
;
3752 int myid
, error
, size
;
3754 BUG_ON(!ss
->use_id
);
3756 size
= sizeof(*newid
) + sizeof(unsigned short) * (depth
+ 1);
3757 newid
= kzalloc(size
, GFP_KERNEL
);
3759 return ERR_PTR(-ENOMEM
);
3761 if (unlikely(!idr_pre_get(&ss
->idr
, GFP_KERNEL
))) {
3765 spin_lock(&ss
->id_lock
);
3766 /* Don't use 0. allocates an ID of 1-65535 */
3767 error
= idr_get_new_above(&ss
->idr
, newid
, 1, &myid
);
3768 spin_unlock(&ss
->id_lock
);
3770 /* Returns error when there are no free spaces for new ID.*/
3775 if (myid
> CSS_ID_MAX
)
3779 newid
->depth
= depth
;
3783 spin_lock(&ss
->id_lock
);
3784 idr_remove(&ss
->idr
, myid
);
3785 spin_unlock(&ss
->id_lock
);
3788 return ERR_PTR(error
);
3792 static int __init
cgroup_subsys_init_idr(struct cgroup_subsys
*ss
)
3794 struct css_id
*newid
;
3795 struct cgroup_subsys_state
*rootcss
;
3797 spin_lock_init(&ss
->id_lock
);
3800 rootcss
= init_css_set
.subsys
[ss
->subsys_id
];
3801 newid
= get_new_cssid(ss
, 0);
3803 return PTR_ERR(newid
);
3805 newid
->stack
[0] = newid
->id
;
3806 newid
->css
= rootcss
;
3807 rootcss
->id
= newid
;
3811 static int alloc_css_id(struct cgroup_subsys
*ss
, struct cgroup
*parent
,
3812 struct cgroup
*child
)
3814 int subsys_id
, i
, depth
= 0;
3815 struct cgroup_subsys_state
*parent_css
, *child_css
;
3816 struct css_id
*child_id
, *parent_id
= NULL
;
3818 subsys_id
= ss
->subsys_id
;
3819 parent_css
= parent
->subsys
[subsys_id
];
3820 child_css
= child
->subsys
[subsys_id
];
3821 depth
= css_depth(parent_css
) + 1;
3822 parent_id
= parent_css
->id
;
3824 child_id
= get_new_cssid(ss
, depth
);
3825 if (IS_ERR(child_id
))
3826 return PTR_ERR(child_id
);
3828 for (i
= 0; i
< depth
; i
++)
3829 child_id
->stack
[i
] = parent_id
->stack
[i
];
3830 child_id
->stack
[depth
] = child_id
->id
;
3832 * child_id->css pointer will be set after this cgroup is available
3833 * see cgroup_populate_dir()
3835 rcu_assign_pointer(child_css
->id
, child_id
);
3841 * css_lookup - lookup css by id
3842 * @ss: cgroup subsys to be looked into.
3845 * Returns pointer to cgroup_subsys_state if there is valid one with id.
3846 * NULL if not. Should be called under rcu_read_lock()
3848 struct cgroup_subsys_state
*css_lookup(struct cgroup_subsys
*ss
, int id
)
3850 struct css_id
*cssid
= NULL
;
3852 BUG_ON(!ss
->use_id
);
3853 cssid
= idr_find(&ss
->idr
, id
);
3855 if (unlikely(!cssid
))
3858 return rcu_dereference(cssid
->css
);
3862 * css_get_next - lookup next cgroup under specified hierarchy.
3863 * @ss: pointer to subsystem
3864 * @id: current position of iteration.
3865 * @root: pointer to css. search tree under this.
3866 * @foundid: position of found object.
3868 * Search next css under the specified hierarchy of rootid. Calling under
3869 * rcu_read_lock() is necessary. Returns NULL if it reaches the end.
3871 struct cgroup_subsys_state
*
3872 css_get_next(struct cgroup_subsys
*ss
, int id
,
3873 struct cgroup_subsys_state
*root
, int *foundid
)
3875 struct cgroup_subsys_state
*ret
= NULL
;
3878 int rootid
= css_id(root
);
3879 int depth
= css_depth(root
);
3884 BUG_ON(!ss
->use_id
);
3885 /* fill start point for scan */
3889 * scan next entry from bitmap(tree), tmpid is updated after
3892 spin_lock(&ss
->id_lock
);
3893 tmp
= idr_get_next(&ss
->idr
, &tmpid
);
3894 spin_unlock(&ss
->id_lock
);
3898 if (tmp
->depth
>= depth
&& tmp
->stack
[depth
] == rootid
) {
3899 ret
= rcu_dereference(tmp
->css
);
3905 /* continue to scan from next id */
3911 #ifdef CONFIG_CGROUP_DEBUG
3912 static struct cgroup_subsys_state
*debug_create(struct cgroup_subsys
*ss
,
3913 struct cgroup
*cont
)
3915 struct cgroup_subsys_state
*css
= kzalloc(sizeof(*css
), GFP_KERNEL
);
3918 return ERR_PTR(-ENOMEM
);
3923 static void debug_destroy(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
3925 kfree(cont
->subsys
[debug_subsys_id
]);
3928 static u64
cgroup_refcount_read(struct cgroup
*cont
, struct cftype
*cft
)
3930 return atomic_read(&cont
->count
);
3933 static u64
debug_taskcount_read(struct cgroup
*cont
, struct cftype
*cft
)
3935 return cgroup_task_count(cont
);
3938 static u64
current_css_set_read(struct cgroup
*cont
, struct cftype
*cft
)
3940 return (u64
)(unsigned long)current
->cgroups
;
3943 static u64
current_css_set_refcount_read(struct cgroup
*cont
,
3949 count
= atomic_read(¤t
->cgroups
->refcount
);
3954 static int current_css_set_cg_links_read(struct cgroup
*cont
,
3956 struct seq_file
*seq
)
3958 struct cg_cgroup_link
*link
;
3961 read_lock(&css_set_lock
);
3963 cg
= rcu_dereference(current
->cgroups
);
3964 list_for_each_entry(link
, &cg
->cg_links
, cg_link_list
) {
3965 struct cgroup
*c
= link
->cgrp
;
3969 name
= c
->dentry
->d_name
.name
;
3972 seq_printf(seq
, "Root %d group %s\n",
3973 c
->root
->hierarchy_id
, name
);
3976 read_unlock(&css_set_lock
);
3980 #define MAX_TASKS_SHOWN_PER_CSS 25
3981 static int cgroup_css_links_read(struct cgroup
*cont
,
3983 struct seq_file
*seq
)
3985 struct cg_cgroup_link
*link
;
3987 read_lock(&css_set_lock
);
3988 list_for_each_entry(link
, &cont
->css_sets
, cgrp_link_list
) {
3989 struct css_set
*cg
= link
->cg
;
3990 struct task_struct
*task
;
3992 seq_printf(seq
, "css_set %p\n", cg
);
3993 list_for_each_entry(task
, &cg
->tasks
, cg_list
) {
3994 if (count
++ > MAX_TASKS_SHOWN_PER_CSS
) {
3995 seq_puts(seq
, " ...\n");
3998 seq_printf(seq
, " task %d\n",
3999 task_pid_vnr(task
));
4003 read_unlock(&css_set_lock
);
4007 static u64
releasable_read(struct cgroup
*cgrp
, struct cftype
*cft
)
4009 return test_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
4012 static struct cftype debug_files
[] = {
4014 .name
= "cgroup_refcount",
4015 .read_u64
= cgroup_refcount_read
,
4018 .name
= "taskcount",
4019 .read_u64
= debug_taskcount_read
,
4023 .name
= "current_css_set",
4024 .read_u64
= current_css_set_read
,
4028 .name
= "current_css_set_refcount",
4029 .read_u64
= current_css_set_refcount_read
,
4033 .name
= "current_css_set_cg_links",
4034 .read_seq_string
= current_css_set_cg_links_read
,
4038 .name
= "cgroup_css_links",
4039 .read_seq_string
= cgroup_css_links_read
,
4043 .name
= "releasable",
4044 .read_u64
= releasable_read
,
4048 static int debug_populate(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
4050 return cgroup_add_files(cont
, ss
, debug_files
,
4051 ARRAY_SIZE(debug_files
));
4054 struct cgroup_subsys debug_subsys
= {
4056 .create
= debug_create
,
4057 .destroy
= debug_destroy
,
4058 .populate
= debug_populate
,
4059 .subsys_id
= debug_subsys_id
,
4061 #endif /* CONFIG_CGROUP_DEBUG */