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Paul Menageddbcc7e2007-10-18 23:39:30 -07001/*
Paul Menageddbcc7e2007-10-18 23:39:30 -07002 * Generic process-grouping system.
3 *
4 * Based originally on the cpuset system, extracted by Paul Menage
5 * Copyright (C) 2006 Google, Inc
6 *
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08007 * Notifications support
8 * Copyright (C) 2009 Nokia Corporation
9 * Author: Kirill A. Shutemov
10 *
Paul Menageddbcc7e2007-10-18 23:39:30 -070011 * Copyright notices from the original cpuset code:
12 * --------------------------------------------------
13 * Copyright (C) 2003 BULL SA.
14 * Copyright (C) 2004-2006 Silicon Graphics, Inc.
15 *
16 * Portions derived from Patrick Mochel's sysfs code.
17 * sysfs is Copyright (c) 2001-3 Patrick Mochel
18 *
19 * 2003-10-10 Written by Simon Derr.
20 * 2003-10-22 Updates by Stephen Hemminger.
21 * 2004 May-July Rework by Paul Jackson.
22 * ---------------------------------------------------
23 *
24 * This file is subject to the terms and conditions of the GNU General Public
25 * License. See the file COPYING in the main directory of the Linux
26 * distribution for more details.
27 */
28
29#include <linux/cgroup.h>
Paul Menagec6d57f32009-09-23 15:56:19 -070030#include <linux/ctype.h>
Paul Menageddbcc7e2007-10-18 23:39:30 -070031#include <linux/errno.h>
32#include <linux/fs.h>
33#include <linux/kernel.h>
34#include <linux/list.h>
35#include <linux/mm.h>
36#include <linux/mutex.h>
37#include <linux/mount.h>
38#include <linux/pagemap.h>
Paul Menagea4243162007-10-18 23:39:35 -070039#include <linux/proc_fs.h>
Paul Menageddbcc7e2007-10-18 23:39:30 -070040#include <linux/rcupdate.h>
41#include <linux/sched.h>
Paul Menage817929e2007-10-18 23:39:36 -070042#include <linux/backing-dev.h>
Paul Menageddbcc7e2007-10-18 23:39:30 -070043#include <linux/seq_file.h>
44#include <linux/slab.h>
45#include <linux/magic.h>
46#include <linux/spinlock.h>
47#include <linux/string.h>
Paul Menagebbcb81d2007-10-18 23:39:32 -070048#include <linux/sort.h>
Paul Menage81a6a5c2007-10-18 23:39:38 -070049#include <linux/kmod.h>
Ben Blume6a11052010-03-10 15:22:09 -080050#include <linux/module.h>
Balbir Singh846c7bb2007-10-18 23:39:44 -070051#include <linux/delayacct.h>
52#include <linux/cgroupstats.h>
Li Zefan472b1052008-04-29 01:00:11 -070053#include <linux/hash.h>
Al Viro3f8206d2008-07-26 03:46:43 -040054#include <linux/namei.h>
Li Zefan096b7fe2009-07-29 15:04:04 -070055#include <linux/pid_namespace.h>
Paul Menage2c6ab6d2009-09-23 15:56:23 -070056#include <linux/idr.h>
Ben Blumd1d9fd32009-09-23 15:56:28 -070057#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -080058#include <linux/eventfd.h>
59#include <linux/poll.h>
Balbir Singh846c7bb2007-10-18 23:39:44 -070060
Paul Menageddbcc7e2007-10-18 23:39:30 -070061#include <asm/atomic.h>
62
Paul Menage81a6a5c2007-10-18 23:39:38 -070063static DEFINE_MUTEX(cgroup_mutex);
64
Ben Blumaae8aab2010-03-10 15:22:07 -080065/*
66 * Generate an array of cgroup subsystem pointers. At boot time, this is
67 * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are
68 * registered after that. The mutable section of this array is protected by
69 * cgroup_mutex.
70 */
Paul Menageddbcc7e2007-10-18 23:39:30 -070071#define SUBSYS(_x) &_x ## _subsys,
Ben Blumaae8aab2010-03-10 15:22:07 -080072static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = {
Paul Menageddbcc7e2007-10-18 23:39:30 -070073#include <linux/cgroup_subsys.h>
74};
75
Paul Menagec6d57f32009-09-23 15:56:19 -070076#define MAX_CGROUP_ROOT_NAMELEN 64
77
Paul Menageddbcc7e2007-10-18 23:39:30 -070078/*
79 * A cgroupfs_root represents the root of a cgroup hierarchy,
80 * and may be associated with a superblock to form an active
81 * hierarchy
82 */
83struct cgroupfs_root {
84 struct super_block *sb;
85
86 /*
87 * The bitmask of subsystems intended to be attached to this
88 * hierarchy
89 */
90 unsigned long subsys_bits;
91
Paul Menage2c6ab6d2009-09-23 15:56:23 -070092 /* Unique id for this hierarchy. */
93 int hierarchy_id;
94
Paul Menageddbcc7e2007-10-18 23:39:30 -070095 /* The bitmask of subsystems currently attached to this hierarchy */
96 unsigned long actual_subsys_bits;
97
98 /* A list running through the attached subsystems */
99 struct list_head subsys_list;
100
101 /* The root cgroup for this hierarchy */
102 struct cgroup top_cgroup;
103
104 /* Tracks how many cgroups are currently defined in hierarchy.*/
105 int number_of_cgroups;
106
Li Zefane5f6a862009-01-07 18:07:41 -0800107 /* A list running through the active hierarchies */
Paul Menageddbcc7e2007-10-18 23:39:30 -0700108 struct list_head root_list;
109
110 /* Hierarchy-specific flags */
111 unsigned long flags;
Paul Menage81a6a5c2007-10-18 23:39:38 -0700112
Paul Menagee788e062008-07-25 01:46:59 -0700113 /* The path to use for release notifications. */
Paul Menage81a6a5c2007-10-18 23:39:38 -0700114 char release_agent_path[PATH_MAX];
Paul Menagec6d57f32009-09-23 15:56:19 -0700115
116 /* The name for this hierarchy - may be empty */
117 char name[MAX_CGROUP_ROOT_NAMELEN];
Paul Menageddbcc7e2007-10-18 23:39:30 -0700118};
119
Paul Menageddbcc7e2007-10-18 23:39:30 -0700120/*
121 * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
122 * subsystems that are otherwise unattached - it never has more than a
123 * single cgroup, and all tasks are part of that cgroup.
124 */
125static struct cgroupfs_root rootnode;
126
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700127/*
128 * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
129 * cgroup_subsys->use_id != 0.
130 */
131#define CSS_ID_MAX (65535)
132struct css_id {
133 /*
134 * The css to which this ID points. This pointer is set to valid value
135 * after cgroup is populated. If cgroup is removed, this will be NULL.
136 * This pointer is expected to be RCU-safe because destroy()
137 * is called after synchronize_rcu(). But for safe use, css_is_removed()
138 * css_tryget() should be used for avoiding race.
139 */
Arnd Bergmann2c392b82010-02-24 19:41:39 +0100140 struct cgroup_subsys_state __rcu *css;
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700141 /*
142 * ID of this css.
143 */
144 unsigned short id;
145 /*
146 * Depth in hierarchy which this ID belongs to.
147 */
148 unsigned short depth;
149 /*
150 * ID is freed by RCU. (and lookup routine is RCU safe.)
151 */
152 struct rcu_head rcu_head;
153 /*
154 * Hierarchy of CSS ID belongs to.
155 */
156 unsigned short stack[0]; /* Array of Length (depth+1) */
157};
158
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -0800159/*
160 * cgroup_event represents events which userspace want to recieve.
161 */
162struct cgroup_event {
163 /*
164 * Cgroup which the event belongs to.
165 */
166 struct cgroup *cgrp;
167 /*
168 * Control file which the event associated.
169 */
170 struct cftype *cft;
171 /*
172 * eventfd to signal userspace about the event.
173 */
174 struct eventfd_ctx *eventfd;
175 /*
176 * Each of these stored in a list by the cgroup.
177 */
178 struct list_head list;
179 /*
180 * All fields below needed to unregister event when
181 * userspace closes eventfd.
182 */
183 poll_table pt;
184 wait_queue_head_t *wqh;
185 wait_queue_t wait;
186 struct work_struct remove;
187};
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700188
Paul Menageddbcc7e2007-10-18 23:39:30 -0700189/* The list of hierarchy roots */
190
191static LIST_HEAD(roots);
Paul Menage817929e2007-10-18 23:39:36 -0700192static int root_count;
Paul Menageddbcc7e2007-10-18 23:39:30 -0700193
Paul Menage2c6ab6d2009-09-23 15:56:23 -0700194static DEFINE_IDA(hierarchy_ida);
195static int next_hierarchy_id;
196static DEFINE_SPINLOCK(hierarchy_id_lock);
197
Paul Menageddbcc7e2007-10-18 23:39:30 -0700198/* dummytop is a shorthand for the dummy hierarchy's top cgroup */
199#define dummytop (&rootnode.top_cgroup)
200
201/* This flag indicates whether tasks in the fork and exit paths should
Li Zefana043e3b2008-02-23 15:24:09 -0800202 * check for fork/exit handlers to call. This avoids us having to do
203 * extra work in the fork/exit path if none of the subsystems need to
204 * be called.
Paul Menageddbcc7e2007-10-18 23:39:30 -0700205 */
Li Zefan8947f9d2008-07-25 01:46:56 -0700206static int need_forkexit_callback __read_mostly;
Paul Menageddbcc7e2007-10-18 23:39:30 -0700207
Paul E. McKenneyd11c5632010-02-22 17:04:50 -0800208#ifdef CONFIG_PROVE_LOCKING
209int cgroup_lock_is_held(void)
210{
211 return lockdep_is_held(&cgroup_mutex);
212}
213#else /* #ifdef CONFIG_PROVE_LOCKING */
214int cgroup_lock_is_held(void)
215{
216 return mutex_is_locked(&cgroup_mutex);
217}
218#endif /* #else #ifdef CONFIG_PROVE_LOCKING */
219
220EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
221
Paul Menageddbcc7e2007-10-18 23:39:30 -0700222/* convenient tests for these bits */
Paul Menagebd89aab2007-10-18 23:40:44 -0700223inline int cgroup_is_removed(const struct cgroup *cgrp)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700224{
Paul Menagebd89aab2007-10-18 23:40:44 -0700225 return test_bit(CGRP_REMOVED, &cgrp->flags);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700226}
227
228/* bits in struct cgroupfs_root flags field */
229enum {
230 ROOT_NOPREFIX, /* mounted subsystems have no named prefix */
231};
232
Adrian Bunke9685a02008-02-07 00:13:46 -0800233static int cgroup_is_releasable(const struct cgroup *cgrp)
Paul Menage81a6a5c2007-10-18 23:39:38 -0700234{
235 const int bits =
Paul Menagebd89aab2007-10-18 23:40:44 -0700236 (1 << CGRP_RELEASABLE) |
237 (1 << CGRP_NOTIFY_ON_RELEASE);
238 return (cgrp->flags & bits) == bits;
Paul Menage81a6a5c2007-10-18 23:39:38 -0700239}
240
Adrian Bunke9685a02008-02-07 00:13:46 -0800241static int notify_on_release(const struct cgroup *cgrp)
Paul Menage81a6a5c2007-10-18 23:39:38 -0700242{
Paul Menagebd89aab2007-10-18 23:40:44 -0700243 return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
Paul Menage81a6a5c2007-10-18 23:39:38 -0700244}
245
Daniel Lezcano97978e62010-10-27 15:33:35 -0700246static int clone_children(const struct cgroup *cgrp)
247{
248 return test_bit(CGRP_CLONE_CHILDREN, &cgrp->flags);
249}
250
Paul Menageddbcc7e2007-10-18 23:39:30 -0700251/*
252 * for_each_subsys() allows you to iterate on each subsystem attached to
253 * an active hierarchy
254 */
255#define for_each_subsys(_root, _ss) \
256list_for_each_entry(_ss, &_root->subsys_list, sibling)
257
Li Zefane5f6a862009-01-07 18:07:41 -0800258/* for_each_active_root() allows you to iterate across the active hierarchies */
259#define for_each_active_root(_root) \
Paul Menageddbcc7e2007-10-18 23:39:30 -0700260list_for_each_entry(_root, &roots, root_list)
261
Paul Menage81a6a5c2007-10-18 23:39:38 -0700262/* the list of cgroups eligible for automatic release. Protected by
263 * release_list_lock */
264static LIST_HEAD(release_list);
265static DEFINE_SPINLOCK(release_list_lock);
266static void cgroup_release_agent(struct work_struct *work);
267static DECLARE_WORK(release_agent_work, cgroup_release_agent);
Paul Menagebd89aab2007-10-18 23:40:44 -0700268static void check_for_release(struct cgroup *cgrp);
Paul Menage81a6a5c2007-10-18 23:39:38 -0700269
Paul Menage817929e2007-10-18 23:39:36 -0700270/* Link structure for associating css_set objects with cgroups */
271struct cg_cgroup_link {
272 /*
273 * List running through cg_cgroup_links associated with a
274 * cgroup, anchored on cgroup->css_sets
275 */
Paul Menagebd89aab2007-10-18 23:40:44 -0700276 struct list_head cgrp_link_list;
Paul Menage7717f7b2009-09-23 15:56:22 -0700277 struct cgroup *cgrp;
Paul Menage817929e2007-10-18 23:39:36 -0700278 /*
279 * List running through cg_cgroup_links pointing at a
280 * single css_set object, anchored on css_set->cg_links
281 */
282 struct list_head cg_link_list;
283 struct css_set *cg;
284};
285
286/* The default css_set - used by init and its children prior to any
287 * hierarchies being mounted. It contains a pointer to the root state
288 * for each subsystem. Also used to anchor the list of css_sets. Not
289 * reference-counted, to improve performance when child cgroups
290 * haven't been created.
291 */
292
293static struct css_set init_css_set;
294static struct cg_cgroup_link init_css_set_link;
295
Ben Blume6a11052010-03-10 15:22:09 -0800296static int cgroup_init_idr(struct cgroup_subsys *ss,
297 struct cgroup_subsys_state *css);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700298
Paul Menage817929e2007-10-18 23:39:36 -0700299/* css_set_lock protects the list of css_set objects, and the
300 * chain of tasks off each css_set. Nests outside task->alloc_lock
301 * due to cgroup_iter_start() */
302static DEFINE_RWLOCK(css_set_lock);
303static int css_set_count;
304
Paul Menage7717f7b2009-09-23 15:56:22 -0700305/*
306 * hash table for cgroup groups. This improves the performance to find
307 * an existing css_set. This hash doesn't (currently) take into
308 * account cgroups in empty hierarchies.
309 */
Li Zefan472b1052008-04-29 01:00:11 -0700310#define CSS_SET_HASH_BITS 7
311#define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS)
312static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE];
313
314static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[])
315{
316 int i;
317 int index;
318 unsigned long tmp = 0UL;
319
320 for (i = 0; i < CGROUP_SUBSYS_COUNT; i++)
321 tmp += (unsigned long)css[i];
322 tmp = (tmp >> 16) ^ tmp;
323
324 index = hash_long(tmp, CSS_SET_HASH_BITS);
325
326 return &css_set_table[index];
327}
328
Ben Blumc3783692009-09-23 15:56:29 -0700329static void free_css_set_rcu(struct rcu_head *obj)
330{
331 struct css_set *cg = container_of(obj, struct css_set, rcu_head);
332 kfree(cg);
333}
334
Paul Menage817929e2007-10-18 23:39:36 -0700335/* We don't maintain the lists running through each css_set to its
336 * task until after the first call to cgroup_iter_start(). This
337 * reduces the fork()/exit() overhead for people who have cgroups
338 * compiled into their kernel but not actually in use */
Li Zefan8947f9d2008-07-25 01:46:56 -0700339static int use_task_css_set_links __read_mostly;
Paul Menage817929e2007-10-18 23:39:36 -0700340
Paul Menage2c6ab6d2009-09-23 15:56:23 -0700341static void __put_css_set(struct css_set *cg, int taskexit)
Paul Menageb4f48b62007-10-18 23:39:33 -0700342{
KOSAKI Motohiro71cbb942008-07-25 01:46:55 -0700343 struct cg_cgroup_link *link;
344 struct cg_cgroup_link *saved_link;
Lai Jiangshan146aa1b2008-10-18 20:28:03 -0700345 /*
346 * Ensure that the refcount doesn't hit zero while any readers
347 * can see it. Similar to atomic_dec_and_lock(), but for an
348 * rwlock
349 */
350 if (atomic_add_unless(&cg->refcount, -1, 1))
351 return;
352 write_lock(&css_set_lock);
353 if (!atomic_dec_and_test(&cg->refcount)) {
354 write_unlock(&css_set_lock);
355 return;
356 }
Paul Menage81a6a5c2007-10-18 23:39:38 -0700357
Paul Menage2c6ab6d2009-09-23 15:56:23 -0700358 /* This css_set is dead. unlink it and release cgroup refcounts */
359 hlist_del(&cg->hlist);
360 css_set_count--;
361
362 list_for_each_entry_safe(link, saved_link, &cg->cg_links,
363 cg_link_list) {
364 struct cgroup *cgrp = link->cgrp;
365 list_del(&link->cg_link_list);
366 list_del(&link->cgrp_link_list);
Paul Menagebd89aab2007-10-18 23:40:44 -0700367 if (atomic_dec_and_test(&cgrp->count) &&
368 notify_on_release(cgrp)) {
Paul Menage81a6a5c2007-10-18 23:39:38 -0700369 if (taskexit)
Paul Menagebd89aab2007-10-18 23:40:44 -0700370 set_bit(CGRP_RELEASABLE, &cgrp->flags);
371 check_for_release(cgrp);
Paul Menage81a6a5c2007-10-18 23:39:38 -0700372 }
Paul Menage2c6ab6d2009-09-23 15:56:23 -0700373
374 kfree(link);
Paul Menage81a6a5c2007-10-18 23:39:38 -0700375 }
Paul Menage2c6ab6d2009-09-23 15:56:23 -0700376
377 write_unlock(&css_set_lock);
Ben Blumc3783692009-09-23 15:56:29 -0700378 call_rcu(&cg->rcu_head, free_css_set_rcu);
Paul Menage817929e2007-10-18 23:39:36 -0700379}
380
381/*
382 * refcounted get/put for css_set objects
383 */
384static inline void get_css_set(struct css_set *cg)
385{
Lai Jiangshan146aa1b2008-10-18 20:28:03 -0700386 atomic_inc(&cg->refcount);
Paul Menage817929e2007-10-18 23:39:36 -0700387}
388
389static inline void put_css_set(struct css_set *cg)
390{
Lai Jiangshan146aa1b2008-10-18 20:28:03 -0700391 __put_css_set(cg, 0);
Paul Menage817929e2007-10-18 23:39:36 -0700392}
393
Paul Menage81a6a5c2007-10-18 23:39:38 -0700394static inline void put_css_set_taskexit(struct css_set *cg)
395{
Lai Jiangshan146aa1b2008-10-18 20:28:03 -0700396 __put_css_set(cg, 1);
Paul Menage81a6a5c2007-10-18 23:39:38 -0700397}
398
Paul Menage817929e2007-10-18 23:39:36 -0700399/*
Paul Menage7717f7b2009-09-23 15:56:22 -0700400 * compare_css_sets - helper function for find_existing_css_set().
401 * @cg: candidate css_set being tested
402 * @old_cg: existing css_set for a task
403 * @new_cgrp: cgroup that's being entered by the task
404 * @template: desired set of css pointers in css_set (pre-calculated)
405 *
406 * Returns true if "cg" matches "old_cg" except for the hierarchy
407 * which "new_cgrp" belongs to, for which it should match "new_cgrp".
408 */
409static bool compare_css_sets(struct css_set *cg,
410 struct css_set *old_cg,
411 struct cgroup *new_cgrp,
412 struct cgroup_subsys_state *template[])
413{
414 struct list_head *l1, *l2;
415
416 if (memcmp(template, cg->subsys, sizeof(cg->subsys))) {
417 /* Not all subsystems matched */
418 return false;
419 }
420
421 /*
422 * Compare cgroup pointers in order to distinguish between
423 * different cgroups in heirarchies with no subsystems. We
424 * could get by with just this check alone (and skip the
425 * memcmp above) but on most setups the memcmp check will
426 * avoid the need for this more expensive check on almost all
427 * candidates.
428 */
429
430 l1 = &cg->cg_links;
431 l2 = &old_cg->cg_links;
432 while (1) {
433 struct cg_cgroup_link *cgl1, *cgl2;
434 struct cgroup *cg1, *cg2;
435
436 l1 = l1->next;
437 l2 = l2->next;
438 /* See if we reached the end - both lists are equal length. */
439 if (l1 == &cg->cg_links) {
440 BUG_ON(l2 != &old_cg->cg_links);
441 break;
442 } else {
443 BUG_ON(l2 == &old_cg->cg_links);
444 }
445 /* Locate the cgroups associated with these links. */
446 cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list);
447 cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list);
448 cg1 = cgl1->cgrp;
449 cg2 = cgl2->cgrp;
450 /* Hierarchies should be linked in the same order. */
451 BUG_ON(cg1->root != cg2->root);
452
453 /*
454 * If this hierarchy is the hierarchy of the cgroup
455 * that's changing, then we need to check that this
456 * css_set points to the new cgroup; if it's any other
457 * hierarchy, then this css_set should point to the
458 * same cgroup as the old css_set.
459 */
460 if (cg1->root == new_cgrp->root) {
461 if (cg1 != new_cgrp)
462 return false;
463 } else {
464 if (cg1 != cg2)
465 return false;
466 }
467 }
468 return true;
469}
470
471/*
Paul Menage817929e2007-10-18 23:39:36 -0700472 * find_existing_css_set() is a helper for
473 * find_css_set(), and checks to see whether an existing
Li Zefan472b1052008-04-29 01:00:11 -0700474 * css_set is suitable.
Paul Menage817929e2007-10-18 23:39:36 -0700475 *
476 * oldcg: the cgroup group that we're using before the cgroup
477 * transition
478 *
Paul Menagebd89aab2007-10-18 23:40:44 -0700479 * cgrp: the cgroup that we're moving into
Paul Menage817929e2007-10-18 23:39:36 -0700480 *
481 * template: location in which to build the desired set of subsystem
482 * state objects for the new cgroup group
483 */
Paul Menage817929e2007-10-18 23:39:36 -0700484static struct css_set *find_existing_css_set(
485 struct css_set *oldcg,
Paul Menagebd89aab2007-10-18 23:40:44 -0700486 struct cgroup *cgrp,
Paul Menage817929e2007-10-18 23:39:36 -0700487 struct cgroup_subsys_state *template[])
488{
489 int i;
Paul Menagebd89aab2007-10-18 23:40:44 -0700490 struct cgroupfs_root *root = cgrp->root;
Li Zefan472b1052008-04-29 01:00:11 -0700491 struct hlist_head *hhead;
492 struct hlist_node *node;
493 struct css_set *cg;
Paul Menage817929e2007-10-18 23:39:36 -0700494
Ben Blumaae8aab2010-03-10 15:22:07 -0800495 /*
496 * Build the set of subsystem state objects that we want to see in the
497 * new css_set. while subsystems can change globally, the entries here
498 * won't change, so no need for locking.
499 */
Paul Menage817929e2007-10-18 23:39:36 -0700500 for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
Li Zefan8d53d552008-02-23 15:24:11 -0800501 if (root->subsys_bits & (1UL << i)) {
Paul Menage817929e2007-10-18 23:39:36 -0700502 /* Subsystem is in this hierarchy. So we want
503 * the subsystem state from the new
504 * cgroup */
Paul Menagebd89aab2007-10-18 23:40:44 -0700505 template[i] = cgrp->subsys[i];
Paul Menage817929e2007-10-18 23:39:36 -0700506 } else {
507 /* Subsystem is not in this hierarchy, so we
508 * don't want to change the subsystem state */
509 template[i] = oldcg->subsys[i];
510 }
511 }
512
Li Zefan472b1052008-04-29 01:00:11 -0700513 hhead = css_set_hash(template);
514 hlist_for_each_entry(cg, node, hhead, hlist) {
Paul Menage7717f7b2009-09-23 15:56:22 -0700515 if (!compare_css_sets(cg, oldcg, cgrp, template))
516 continue;
517
518 /* This css_set matches what we need */
519 return cg;
Li Zefan472b1052008-04-29 01:00:11 -0700520 }
Paul Menage817929e2007-10-18 23:39:36 -0700521
522 /* No existing cgroup group matched */
523 return NULL;
524}
525
Paul Menage817929e2007-10-18 23:39:36 -0700526static void free_cg_links(struct list_head *tmp)
527{
KOSAKI Motohiro71cbb942008-07-25 01:46:55 -0700528 struct cg_cgroup_link *link;
529 struct cg_cgroup_link *saved_link;
530
531 list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) {
Paul Menagebd89aab2007-10-18 23:40:44 -0700532 list_del(&link->cgrp_link_list);
Paul Menage817929e2007-10-18 23:39:36 -0700533 kfree(link);
534 }
535}
536
537/*
Li Zefan36553432008-07-29 22:33:19 -0700538 * allocate_cg_links() allocates "count" cg_cgroup_link structures
539 * and chains them on tmp through their cgrp_link_list fields. Returns 0 on
540 * success or a negative error
541 */
542static int allocate_cg_links(int count, struct list_head *tmp)
543{
544 struct cg_cgroup_link *link;
545 int i;
546 INIT_LIST_HEAD(tmp);
547 for (i = 0; i < count; i++) {
548 link = kmalloc(sizeof(*link), GFP_KERNEL);
549 if (!link) {
550 free_cg_links(tmp);
551 return -ENOMEM;
552 }
553 list_add(&link->cgrp_link_list, tmp);
554 }
555 return 0;
556}
557
Li Zefanc12f65d2009-01-07 18:07:42 -0800558/**
559 * link_css_set - a helper function to link a css_set to a cgroup
560 * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links()
561 * @cg: the css_set to be linked
562 * @cgrp: the destination cgroup
563 */
564static void link_css_set(struct list_head *tmp_cg_links,
565 struct css_set *cg, struct cgroup *cgrp)
566{
567 struct cg_cgroup_link *link;
568
569 BUG_ON(list_empty(tmp_cg_links));
570 link = list_first_entry(tmp_cg_links, struct cg_cgroup_link,
571 cgrp_link_list);
572 link->cg = cg;
Paul Menage7717f7b2009-09-23 15:56:22 -0700573 link->cgrp = cgrp;
Paul Menage2c6ab6d2009-09-23 15:56:23 -0700574 atomic_inc(&cgrp->count);
Li Zefanc12f65d2009-01-07 18:07:42 -0800575 list_move(&link->cgrp_link_list, &cgrp->css_sets);
Paul Menage7717f7b2009-09-23 15:56:22 -0700576 /*
577 * Always add links to the tail of the list so that the list
578 * is sorted by order of hierarchy creation
579 */
580 list_add_tail(&link->cg_link_list, &cg->cg_links);
Li Zefanc12f65d2009-01-07 18:07:42 -0800581}
582
Li Zefan36553432008-07-29 22:33:19 -0700583/*
Paul Menage817929e2007-10-18 23:39:36 -0700584 * find_css_set() takes an existing cgroup group and a
585 * cgroup object, and returns a css_set object that's
586 * equivalent to the old group, but with the given cgroup
587 * substituted into the appropriate hierarchy. Must be called with
588 * cgroup_mutex held
589 */
Paul Menage817929e2007-10-18 23:39:36 -0700590static struct css_set *find_css_set(
Paul Menagebd89aab2007-10-18 23:40:44 -0700591 struct css_set *oldcg, struct cgroup *cgrp)
Paul Menage817929e2007-10-18 23:39:36 -0700592{
593 struct css_set *res;
594 struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
Paul Menage817929e2007-10-18 23:39:36 -0700595
596 struct list_head tmp_cg_links;
Paul Menage817929e2007-10-18 23:39:36 -0700597
Li Zefan472b1052008-04-29 01:00:11 -0700598 struct hlist_head *hhead;
Paul Menage7717f7b2009-09-23 15:56:22 -0700599 struct cg_cgroup_link *link;
Li Zefan472b1052008-04-29 01:00:11 -0700600
Paul Menage817929e2007-10-18 23:39:36 -0700601 /* First see if we already have a cgroup group that matches
602 * the desired set */
Li Zefan7e9abd82008-07-25 01:46:54 -0700603 read_lock(&css_set_lock);
Paul Menagebd89aab2007-10-18 23:40:44 -0700604 res = find_existing_css_set(oldcg, cgrp, template);
Paul Menage817929e2007-10-18 23:39:36 -0700605 if (res)
606 get_css_set(res);
Li Zefan7e9abd82008-07-25 01:46:54 -0700607 read_unlock(&css_set_lock);
Paul Menage817929e2007-10-18 23:39:36 -0700608
609 if (res)
610 return res;
611
612 res = kmalloc(sizeof(*res), GFP_KERNEL);
613 if (!res)
614 return NULL;
615
616 /* Allocate all the cg_cgroup_link objects that we'll need */
617 if (allocate_cg_links(root_count, &tmp_cg_links) < 0) {
618 kfree(res);
619 return NULL;
620 }
621
Lai Jiangshan146aa1b2008-10-18 20:28:03 -0700622 atomic_set(&res->refcount, 1);
Paul Menage817929e2007-10-18 23:39:36 -0700623 INIT_LIST_HEAD(&res->cg_links);
624 INIT_LIST_HEAD(&res->tasks);
Li Zefan472b1052008-04-29 01:00:11 -0700625 INIT_HLIST_NODE(&res->hlist);
Paul Menage817929e2007-10-18 23:39:36 -0700626
627 /* Copy the set of subsystem state objects generated in
628 * find_existing_css_set() */
629 memcpy(res->subsys, template, sizeof(res->subsys));
630
631 write_lock(&css_set_lock);
632 /* Add reference counts and links from the new css_set. */
Paul Menage7717f7b2009-09-23 15:56:22 -0700633 list_for_each_entry(link, &oldcg->cg_links, cg_link_list) {
634 struct cgroup *c = link->cgrp;
635 if (c->root == cgrp->root)
636 c = cgrp;
637 link_css_set(&tmp_cg_links, res, c);
638 }
Paul Menage817929e2007-10-18 23:39:36 -0700639
640 BUG_ON(!list_empty(&tmp_cg_links));
641
Paul Menage817929e2007-10-18 23:39:36 -0700642 css_set_count++;
Li Zefan472b1052008-04-29 01:00:11 -0700643
644 /* Add this cgroup group to the hash table */
645 hhead = css_set_hash(res->subsys);
646 hlist_add_head(&res->hlist, hhead);
647
Paul Menage817929e2007-10-18 23:39:36 -0700648 write_unlock(&css_set_lock);
649
650 return res;
Paul Menageb4f48b62007-10-18 23:39:33 -0700651}
652
Paul Menageddbcc7e2007-10-18 23:39:30 -0700653/*
Paul Menage7717f7b2009-09-23 15:56:22 -0700654 * Return the cgroup for "task" from the given hierarchy. Must be
655 * called with cgroup_mutex held.
656 */
657static struct cgroup *task_cgroup_from_root(struct task_struct *task,
658 struct cgroupfs_root *root)
659{
660 struct css_set *css;
661 struct cgroup *res = NULL;
662
663 BUG_ON(!mutex_is_locked(&cgroup_mutex));
664 read_lock(&css_set_lock);
665 /*
666 * No need to lock the task - since we hold cgroup_mutex the
667 * task can't change groups, so the only thing that can happen
668 * is that it exits and its css is set back to init_css_set.
669 */
670 css = task->cgroups;
671 if (css == &init_css_set) {
672 res = &root->top_cgroup;
673 } else {
674 struct cg_cgroup_link *link;
675 list_for_each_entry(link, &css->cg_links, cg_link_list) {
676 struct cgroup *c = link->cgrp;
677 if (c->root == root) {
678 res = c;
679 break;
680 }
681 }
682 }
683 read_unlock(&css_set_lock);
684 BUG_ON(!res);
685 return res;
686}
687
688/*
Paul Menageddbcc7e2007-10-18 23:39:30 -0700689 * There is one global cgroup mutex. We also require taking
690 * task_lock() when dereferencing a task's cgroup subsys pointers.
691 * See "The task_lock() exception", at the end of this comment.
692 *
693 * A task must hold cgroup_mutex to modify cgroups.
694 *
695 * Any task can increment and decrement the count field without lock.
696 * So in general, code holding cgroup_mutex can't rely on the count
697 * field not changing. However, if the count goes to zero, then only
Cliff Wickman956db3c2008-02-07 00:14:43 -0800698 * cgroup_attach_task() can increment it again. Because a count of zero
Paul Menageddbcc7e2007-10-18 23:39:30 -0700699 * means that no tasks are currently attached, therefore there is no
700 * way a task attached to that cgroup can fork (the other way to
701 * increment the count). So code holding cgroup_mutex can safely
702 * assume that if the count is zero, it will stay zero. Similarly, if
703 * a task holds cgroup_mutex on a cgroup with zero count, it
704 * knows that the cgroup won't be removed, as cgroup_rmdir()
705 * needs that mutex.
706 *
Paul Menageddbcc7e2007-10-18 23:39:30 -0700707 * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
708 * (usually) take cgroup_mutex. These are the two most performance
709 * critical pieces of code here. The exception occurs on cgroup_exit(),
710 * when a task in a notify_on_release cgroup exits. Then cgroup_mutex
711 * is taken, and if the cgroup count is zero, a usermode call made
Li Zefana043e3b2008-02-23 15:24:09 -0800712 * to the release agent with the name of the cgroup (path relative to
713 * the root of cgroup file system) as the argument.
Paul Menageddbcc7e2007-10-18 23:39:30 -0700714 *
715 * A cgroup can only be deleted if both its 'count' of using tasks
716 * is zero, and its list of 'children' cgroups is empty. Since all
717 * tasks in the system use _some_ cgroup, and since there is always at
718 * least one task in the system (init, pid == 1), therefore, top_cgroup
719 * always has either children cgroups and/or using tasks. So we don't
720 * need a special hack to ensure that top_cgroup cannot be deleted.
721 *
722 * The task_lock() exception
723 *
724 * The need for this exception arises from the action of
Cliff Wickman956db3c2008-02-07 00:14:43 -0800725 * cgroup_attach_task(), which overwrites one tasks cgroup pointer with
Li Zefana043e3b2008-02-23 15:24:09 -0800726 * another. It does so using cgroup_mutex, however there are
Paul Menageddbcc7e2007-10-18 23:39:30 -0700727 * several performance critical places that need to reference
728 * task->cgroup without the expense of grabbing a system global
729 * mutex. Therefore except as noted below, when dereferencing or, as
Cliff Wickman956db3c2008-02-07 00:14:43 -0800730 * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use
Paul Menageddbcc7e2007-10-18 23:39:30 -0700731 * task_lock(), which acts on a spinlock (task->alloc_lock) already in
732 * the task_struct routinely used for such matters.
733 *
734 * P.S. One more locking exception. RCU is used to guard the
Cliff Wickman956db3c2008-02-07 00:14:43 -0800735 * update of a tasks cgroup pointer by cgroup_attach_task()
Paul Menageddbcc7e2007-10-18 23:39:30 -0700736 */
737
Paul Menageddbcc7e2007-10-18 23:39:30 -0700738/**
739 * cgroup_lock - lock out any changes to cgroup structures
740 *
741 */
Paul Menageddbcc7e2007-10-18 23:39:30 -0700742void cgroup_lock(void)
743{
744 mutex_lock(&cgroup_mutex);
745}
Ben Blum67523c42010-03-10 15:22:11 -0800746EXPORT_SYMBOL_GPL(cgroup_lock);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700747
748/**
749 * cgroup_unlock - release lock on cgroup changes
750 *
751 * Undo the lock taken in a previous cgroup_lock() call.
752 */
Paul Menageddbcc7e2007-10-18 23:39:30 -0700753void cgroup_unlock(void)
754{
755 mutex_unlock(&cgroup_mutex);
756}
Ben Blum67523c42010-03-10 15:22:11 -0800757EXPORT_SYMBOL_GPL(cgroup_unlock);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700758
759/*
760 * A couple of forward declarations required, due to cyclic reference loop:
761 * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
762 * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
763 * -> cgroup_mkdir.
764 */
765
766static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode);
Al Viroc72a04e2011-01-14 05:31:45 +0000767static struct dentry *cgroup_lookup(struct inode *, struct dentry *, struct nameidata *);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700768static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
Paul Menagebd89aab2007-10-18 23:40:44 -0700769static int cgroup_populate_dir(struct cgroup *cgrp);
Alexey Dobriyan6e1d5dc2009-09-21 17:01:11 -0700770static const struct inode_operations cgroup_dir_inode_operations;
Alexey Dobriyan828c0952009-10-01 15:43:56 -0700771static const struct file_operations proc_cgroupstats_operations;
Paul Menagea4243162007-10-18 23:39:35 -0700772
773static struct backing_dev_info cgroup_backing_dev_info = {
Jens Axboed9938312009-06-12 14:45:52 +0200774 .name = "cgroup",
Miklos Szeredie4ad08f2008-04-30 00:54:37 -0700775 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
Paul Menagea4243162007-10-18 23:39:35 -0700776};
Paul Menageddbcc7e2007-10-18 23:39:30 -0700777
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700778static int alloc_css_id(struct cgroup_subsys *ss,
779 struct cgroup *parent, struct cgroup *child);
780
Paul Menageddbcc7e2007-10-18 23:39:30 -0700781static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
782{
783 struct inode *inode = new_inode(sb);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700784
785 if (inode) {
Christoph Hellwig85fe4022010-10-23 11:19:54 -0400786 inode->i_ino = get_next_ino();
Paul Menageddbcc7e2007-10-18 23:39:30 -0700787 inode->i_mode = mode;
David Howells76aac0e2008-11-14 10:39:12 +1100788 inode->i_uid = current_fsuid();
789 inode->i_gid = current_fsgid();
Paul Menageddbcc7e2007-10-18 23:39:30 -0700790 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
791 inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info;
792 }
793 return inode;
794}
795
KAMEZAWA Hiroyuki4fca88c2008-02-07 00:14:27 -0800796/*
797 * Call subsys's pre_destroy handler.
798 * This is called before css refcnt check.
799 */
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -0700800static int cgroup_call_pre_destroy(struct cgroup *cgrp)
KAMEZAWA Hiroyuki4fca88c2008-02-07 00:14:27 -0800801{
802 struct cgroup_subsys *ss;
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -0700803 int ret = 0;
804
KAMEZAWA Hiroyuki4fca88c2008-02-07 00:14:27 -0800805 for_each_subsys(cgrp->root, ss)
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -0700806 if (ss->pre_destroy) {
807 ret = ss->pre_destroy(ss, cgrp);
808 if (ret)
Kirill A. Shutemov4ab78682010-03-10 15:22:34 -0800809 break;
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -0700810 }
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -0800811
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -0700812 return ret;
KAMEZAWA Hiroyuki4fca88c2008-02-07 00:14:27 -0800813}
814
Paul Menagea47295e2009-01-07 18:07:44 -0800815static void free_cgroup_rcu(struct rcu_head *obj)
816{
817 struct cgroup *cgrp = container_of(obj, struct cgroup, rcu_head);
818
819 kfree(cgrp);
820}
821
Paul Menageddbcc7e2007-10-18 23:39:30 -0700822static void cgroup_diput(struct dentry *dentry, struct inode *inode)
823{
824 /* is dentry a directory ? if so, kfree() associated cgroup */
825 if (S_ISDIR(inode->i_mode)) {
Paul Menagebd89aab2007-10-18 23:40:44 -0700826 struct cgroup *cgrp = dentry->d_fsdata;
Paul Menage8dc4f3e2008-02-07 00:13:45 -0800827 struct cgroup_subsys *ss;
Paul Menagebd89aab2007-10-18 23:40:44 -0700828 BUG_ON(!(cgroup_is_removed(cgrp)));
Paul Menage81a6a5c2007-10-18 23:39:38 -0700829 /* It's possible for external users to be holding css
830 * reference counts on a cgroup; css_put() needs to
831 * be able to access the cgroup after decrementing
832 * the reference count in order to know if it needs to
833 * queue the cgroup to be handled by the release
834 * agent */
835 synchronize_rcu();
Paul Menage8dc4f3e2008-02-07 00:13:45 -0800836
837 mutex_lock(&cgroup_mutex);
838 /*
839 * Release the subsystem state objects.
840 */
Li Zefan75139b82009-01-07 18:07:33 -0800841 for_each_subsys(cgrp->root, ss)
842 ss->destroy(ss, cgrp);
Paul Menage8dc4f3e2008-02-07 00:13:45 -0800843
844 cgrp->root->number_of_cgroups--;
845 mutex_unlock(&cgroup_mutex);
846
Paul Menagea47295e2009-01-07 18:07:44 -0800847 /*
848 * Drop the active superblock reference that we took when we
849 * created the cgroup
850 */
Paul Menage8dc4f3e2008-02-07 00:13:45 -0800851 deactivate_super(cgrp->root->sb);
852
Ben Blum72a8cb32009-09-23 15:56:27 -0700853 /*
854 * if we're getting rid of the cgroup, refcount should ensure
855 * that there are no pidlists left.
856 */
857 BUG_ON(!list_empty(&cgrp->pidlists));
858
Paul Menagea47295e2009-01-07 18:07:44 -0800859 call_rcu(&cgrp->rcu_head, free_cgroup_rcu);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700860 }
861 iput(inode);
862}
863
Al Viroc72a04e2011-01-14 05:31:45 +0000864static int cgroup_delete(const struct dentry *d)
865{
866 return 1;
867}
868
Paul Menageddbcc7e2007-10-18 23:39:30 -0700869static void remove_dir(struct dentry *d)
870{
871 struct dentry *parent = dget(d->d_parent);
872
873 d_delete(d);
874 simple_rmdir(parent->d_inode, d);
875 dput(parent);
876}
877
878static void cgroup_clear_directory(struct dentry *dentry)
879{
880 struct list_head *node;
881
882 BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100883 spin_lock(&dentry->d_lock);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700884 node = dentry->d_subdirs.next;
885 while (node != &dentry->d_subdirs) {
886 struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100887
888 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700889 list_del_init(node);
890 if (d->d_inode) {
891 /* This should never be called on a cgroup
892 * directory with child cgroups */
893 BUG_ON(d->d_inode->i_mode & S_IFDIR);
Nick Piggindc0474b2011-01-07 17:49:43 +1100894 dget_dlock(d);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100895 spin_unlock(&d->d_lock);
896 spin_unlock(&dentry->d_lock);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700897 d_delete(d);
898 simple_unlink(dentry->d_inode, d);
899 dput(d);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100900 spin_lock(&dentry->d_lock);
901 } else
902 spin_unlock(&d->d_lock);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700903 node = dentry->d_subdirs.next;
904 }
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100905 spin_unlock(&dentry->d_lock);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700906}
907
908/*
909 * NOTE : the dentry must have been dget()'ed
910 */
911static void cgroup_d_remove_dir(struct dentry *dentry)
912{
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100913 struct dentry *parent;
914
Paul Menageddbcc7e2007-10-18 23:39:30 -0700915 cgroup_clear_directory(dentry);
916
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100917 parent = dentry->d_parent;
918 spin_lock(&parent->d_lock);
Li Zefan3ec762a2011-01-14 11:34:34 +0800919 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700920 list_del_init(&dentry->d_u.d_child);
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100921 spin_unlock(&dentry->d_lock);
922 spin_unlock(&parent->d_lock);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700923 remove_dir(dentry);
924}
925
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -0700926/*
927 * A queue for waiters to do rmdir() cgroup. A tasks will sleep when
928 * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some
929 * reference to css->refcnt. In general, this refcnt is expected to goes down
930 * to zero, soon.
931 *
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -0700932 * CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex;
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -0700933 */
934DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq);
935
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -0700936static void cgroup_wakeup_rmdir_waiter(struct cgroup *cgrp)
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -0700937{
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -0700938 if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)))
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -0700939 wake_up_all(&cgroup_rmdir_waitq);
940}
941
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -0700942void cgroup_exclude_rmdir(struct cgroup_subsys_state *css)
943{
944 css_get(css);
945}
946
947void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css)
948{
949 cgroup_wakeup_rmdir_waiter(css->cgroup);
950 css_put(css);
951}
952
Ben Blumaae8aab2010-03-10 15:22:07 -0800953/*
Ben Blumcf5d5942010-03-10 15:22:09 -0800954 * Call with cgroup_mutex held. Drops reference counts on modules, including
955 * any duplicate ones that parse_cgroupfs_options took. If this function
956 * returns an error, no reference counts are touched.
Ben Blumaae8aab2010-03-10 15:22:07 -0800957 */
Paul Menageddbcc7e2007-10-18 23:39:30 -0700958static int rebind_subsystems(struct cgroupfs_root *root,
959 unsigned long final_bits)
960{
961 unsigned long added_bits, removed_bits;
Paul Menagebd89aab2007-10-18 23:40:44 -0700962 struct cgroup *cgrp = &root->top_cgroup;
Paul Menageddbcc7e2007-10-18 23:39:30 -0700963 int i;
964
Ben Blumaae8aab2010-03-10 15:22:07 -0800965 BUG_ON(!mutex_is_locked(&cgroup_mutex));
966
Paul Menageddbcc7e2007-10-18 23:39:30 -0700967 removed_bits = root->actual_subsys_bits & ~final_bits;
968 added_bits = final_bits & ~root->actual_subsys_bits;
969 /* Check that any added subsystems are currently free */
970 for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
Li Zefan8d53d552008-02-23 15:24:11 -0800971 unsigned long bit = 1UL << i;
Paul Menageddbcc7e2007-10-18 23:39:30 -0700972 struct cgroup_subsys *ss = subsys[i];
973 if (!(bit & added_bits))
974 continue;
Ben Blumaae8aab2010-03-10 15:22:07 -0800975 /*
976 * Nobody should tell us to do a subsys that doesn't exist:
977 * parse_cgroupfs_options should catch that case and refcounts
978 * ensure that subsystems won't disappear once selected.
979 */
980 BUG_ON(ss == NULL);
Paul Menageddbcc7e2007-10-18 23:39:30 -0700981 if (ss->root != &rootnode) {
982 /* Subsystem isn't free */
983 return -EBUSY;
984 }
985 }
986
987 /* Currently we don't handle adding/removing subsystems when
988 * any child cgroups exist. This is theoretically supportable
989 * but involves complex error handling, so it's being left until
990 * later */
Paul Menage307257c2008-12-15 13:54:22 -0800991 if (root->number_of_cgroups > 1)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700992 return -EBUSY;
993
994 /* Process each subsystem */
995 for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
996 struct cgroup_subsys *ss = subsys[i];
997 unsigned long bit = 1UL << i;
998 if (bit & added_bits) {
999 /* We're binding this subsystem to this hierarchy */
Ben Blumaae8aab2010-03-10 15:22:07 -08001000 BUG_ON(ss == NULL);
Paul Menagebd89aab2007-10-18 23:40:44 -07001001 BUG_ON(cgrp->subsys[i]);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001002 BUG_ON(!dummytop->subsys[i]);
1003 BUG_ON(dummytop->subsys[i]->cgroup != dummytop);
Paul Menage999cd8a2009-01-07 18:08:36 -08001004 mutex_lock(&ss->hierarchy_mutex);
Paul Menagebd89aab2007-10-18 23:40:44 -07001005 cgrp->subsys[i] = dummytop->subsys[i];
1006 cgrp->subsys[i]->cgroup = cgrp;
Li Zefan33a68ac2009-01-07 18:07:42 -08001007 list_move(&ss->sibling, &root->subsys_list);
Lai Jiangshanb2aa30f2009-01-07 18:07:37 -08001008 ss->root = root;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001009 if (ss->bind)
Paul Menagebd89aab2007-10-18 23:40:44 -07001010 ss->bind(ss, cgrp);
Paul Menage999cd8a2009-01-07 18:08:36 -08001011 mutex_unlock(&ss->hierarchy_mutex);
Ben Blumcf5d5942010-03-10 15:22:09 -08001012 /* refcount was already taken, and we're keeping it */
Paul Menageddbcc7e2007-10-18 23:39:30 -07001013 } else if (bit & removed_bits) {
1014 /* We're removing this subsystem */
Ben Blumaae8aab2010-03-10 15:22:07 -08001015 BUG_ON(ss == NULL);
Paul Menagebd89aab2007-10-18 23:40:44 -07001016 BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]);
1017 BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
Paul Menage999cd8a2009-01-07 18:08:36 -08001018 mutex_lock(&ss->hierarchy_mutex);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001019 if (ss->bind)
1020 ss->bind(ss, dummytop);
1021 dummytop->subsys[i]->cgroup = dummytop;
Paul Menagebd89aab2007-10-18 23:40:44 -07001022 cgrp->subsys[i] = NULL;
Lai Jiangshanb2aa30f2009-01-07 18:07:37 -08001023 subsys[i]->root = &rootnode;
Li Zefan33a68ac2009-01-07 18:07:42 -08001024 list_move(&ss->sibling, &rootnode.subsys_list);
Paul Menage999cd8a2009-01-07 18:08:36 -08001025 mutex_unlock(&ss->hierarchy_mutex);
Ben Blumcf5d5942010-03-10 15:22:09 -08001026 /* subsystem is now free - drop reference on module */
1027 module_put(ss->module);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001028 } else if (bit & final_bits) {
1029 /* Subsystem state should already exist */
Ben Blumaae8aab2010-03-10 15:22:07 -08001030 BUG_ON(ss == NULL);
Paul Menagebd89aab2007-10-18 23:40:44 -07001031 BUG_ON(!cgrp->subsys[i]);
Ben Blumcf5d5942010-03-10 15:22:09 -08001032 /*
1033 * a refcount was taken, but we already had one, so
1034 * drop the extra reference.
1035 */
1036 module_put(ss->module);
1037#ifdef CONFIG_MODULE_UNLOAD
1038 BUG_ON(ss->module && !module_refcount(ss->module));
1039#endif
Paul Menageddbcc7e2007-10-18 23:39:30 -07001040 } else {
1041 /* Subsystem state shouldn't exist */
Paul Menagebd89aab2007-10-18 23:40:44 -07001042 BUG_ON(cgrp->subsys[i]);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001043 }
1044 }
1045 root->subsys_bits = root->actual_subsys_bits = final_bits;
1046 synchronize_rcu();
1047
1048 return 0;
1049}
1050
1051static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs)
1052{
1053 struct cgroupfs_root *root = vfs->mnt_sb->s_fs_info;
1054 struct cgroup_subsys *ss;
1055
1056 mutex_lock(&cgroup_mutex);
1057 for_each_subsys(root, ss)
1058 seq_printf(seq, ",%s", ss->name);
1059 if (test_bit(ROOT_NOPREFIX, &root->flags))
1060 seq_puts(seq, ",noprefix");
Paul Menage81a6a5c2007-10-18 23:39:38 -07001061 if (strlen(root->release_agent_path))
1062 seq_printf(seq, ",release_agent=%s", root->release_agent_path);
Daniel Lezcano97978e62010-10-27 15:33:35 -07001063 if (clone_children(&root->top_cgroup))
1064 seq_puts(seq, ",clone_children");
Paul Menagec6d57f32009-09-23 15:56:19 -07001065 if (strlen(root->name))
1066 seq_printf(seq, ",name=%s", root->name);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001067 mutex_unlock(&cgroup_mutex);
1068 return 0;
1069}
1070
1071struct cgroup_sb_opts {
1072 unsigned long subsys_bits;
1073 unsigned long flags;
Paul Menage81a6a5c2007-10-18 23:39:38 -07001074 char *release_agent;
Daniel Lezcano97978e62010-10-27 15:33:35 -07001075 bool clone_children;
Paul Menagec6d57f32009-09-23 15:56:19 -07001076 char *name;
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001077 /* User explicitly requested empty subsystem */
1078 bool none;
Paul Menagec6d57f32009-09-23 15:56:19 -07001079
1080 struct cgroupfs_root *new_root;
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001081
Paul Menageddbcc7e2007-10-18 23:39:30 -07001082};
1083
Ben Blumaae8aab2010-03-10 15:22:07 -08001084/*
1085 * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call
Ben Blumcf5d5942010-03-10 15:22:09 -08001086 * with cgroup_mutex held to protect the subsys[] array. This function takes
1087 * refcounts on subsystems to be used, unless it returns error, in which case
1088 * no refcounts are taken.
Ben Blumaae8aab2010-03-10 15:22:07 -08001089 */
Ben Blumcf5d5942010-03-10 15:22:09 -08001090static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
Paul Menageddbcc7e2007-10-18 23:39:30 -07001091{
Daniel Lezcano32a8cf22010-10-27 15:33:37 -07001092 char *token, *o = data;
1093 bool all_ss = false, one_ss = false;
Li Zefanf9ab5b52009-06-17 16:26:33 -07001094 unsigned long mask = (unsigned long)-1;
Ben Blumcf5d5942010-03-10 15:22:09 -08001095 int i;
1096 bool module_pin_failed = false;
Li Zefanf9ab5b52009-06-17 16:26:33 -07001097
Ben Blumaae8aab2010-03-10 15:22:07 -08001098 BUG_ON(!mutex_is_locked(&cgroup_mutex));
1099
Li Zefanf9ab5b52009-06-17 16:26:33 -07001100#ifdef CONFIG_CPUSETS
1101 mask = ~(1UL << cpuset_subsys_id);
1102#endif
Paul Menageddbcc7e2007-10-18 23:39:30 -07001103
Paul Menagec6d57f32009-09-23 15:56:19 -07001104 memset(opts, 0, sizeof(*opts));
Paul Menageddbcc7e2007-10-18 23:39:30 -07001105
1106 while ((token = strsep(&o, ",")) != NULL) {
1107 if (!*token)
1108 return -EINVAL;
Daniel Lezcano32a8cf22010-10-27 15:33:37 -07001109 if (!strcmp(token, "none")) {
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001110 /* Explicitly have no subsystems */
1111 opts->none = true;
Daniel Lezcano32a8cf22010-10-27 15:33:37 -07001112 continue;
1113 }
1114 if (!strcmp(token, "all")) {
1115 /* Mutually exclusive option 'all' + subsystem name */
1116 if (one_ss)
1117 return -EINVAL;
1118 all_ss = true;
1119 continue;
1120 }
1121 if (!strcmp(token, "noprefix")) {
Paul Menageddbcc7e2007-10-18 23:39:30 -07001122 set_bit(ROOT_NOPREFIX, &opts->flags);
Daniel Lezcano32a8cf22010-10-27 15:33:37 -07001123 continue;
1124 }
1125 if (!strcmp(token, "clone_children")) {
Daniel Lezcano97978e62010-10-27 15:33:35 -07001126 opts->clone_children = true;
Daniel Lezcano32a8cf22010-10-27 15:33:37 -07001127 continue;
1128 }
1129 if (!strncmp(token, "release_agent=", 14)) {
Paul Menage81a6a5c2007-10-18 23:39:38 -07001130 /* Specifying two release agents is forbidden */
1131 if (opts->release_agent)
1132 return -EINVAL;
Paul Menagec6d57f32009-09-23 15:56:19 -07001133 opts->release_agent =
Dan Carpentere400c282010-08-10 18:02:54 -07001134 kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
Paul Menage81a6a5c2007-10-18 23:39:38 -07001135 if (!opts->release_agent)
1136 return -ENOMEM;
Daniel Lezcano32a8cf22010-10-27 15:33:37 -07001137 continue;
1138 }
1139 if (!strncmp(token, "name=", 5)) {
Paul Menagec6d57f32009-09-23 15:56:19 -07001140 const char *name = token + 5;
1141 /* Can't specify an empty name */
1142 if (!strlen(name))
1143 return -EINVAL;
1144 /* Must match [\w.-]+ */
1145 for (i = 0; i < strlen(name); i++) {
1146 char c = name[i];
1147 if (isalnum(c))
1148 continue;
1149 if ((c == '.') || (c == '-') || (c == '_'))
1150 continue;
1151 return -EINVAL;
1152 }
1153 /* Specifying two names is forbidden */
1154 if (opts->name)
1155 return -EINVAL;
1156 opts->name = kstrndup(name,
Dan Carpentere400c282010-08-10 18:02:54 -07001157 MAX_CGROUP_ROOT_NAMELEN - 1,
Paul Menagec6d57f32009-09-23 15:56:19 -07001158 GFP_KERNEL);
1159 if (!opts->name)
1160 return -ENOMEM;
Daniel Lezcano32a8cf22010-10-27 15:33:37 -07001161
1162 continue;
1163 }
1164
1165 for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
1166 struct cgroup_subsys *ss = subsys[i];
1167 if (ss == NULL)
1168 continue;
1169 if (strcmp(token, ss->name))
1170 continue;
1171 if (ss->disabled)
1172 continue;
1173
1174 /* Mutually exclusive option 'all' + subsystem name */
1175 if (all_ss)
1176 return -EINVAL;
1177 set_bit(i, &opts->subsys_bits);
1178 one_ss = true;
1179
1180 break;
1181 }
1182 if (i == CGROUP_SUBSYS_COUNT)
1183 return -ENOENT;
1184 }
1185
1186 /*
1187 * If the 'all' option was specified select all the subsystems,
1188 * otherwise 'all, 'none' and a subsystem name options were not
1189 * specified, let's default to 'all'
1190 */
1191 if (all_ss || (!all_ss && !one_ss && !opts->none)) {
1192 for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
1193 struct cgroup_subsys *ss = subsys[i];
1194 if (ss == NULL)
1195 continue;
1196 if (ss->disabled)
1197 continue;
1198 set_bit(i, &opts->subsys_bits);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001199 }
1200 }
1201
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001202 /* Consistency checks */
1203
Li Zefanf9ab5b52009-06-17 16:26:33 -07001204 /*
1205 * Option noprefix was introduced just for backward compatibility
1206 * with the old cpuset, so we allow noprefix only if mounting just
1207 * the cpuset subsystem.
1208 */
1209 if (test_bit(ROOT_NOPREFIX, &opts->flags) &&
1210 (opts->subsys_bits & mask))
1211 return -EINVAL;
1212
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001213
1214 /* Can't specify "none" and some subsystems */
1215 if (opts->subsys_bits && opts->none)
1216 return -EINVAL;
1217
1218 /*
1219 * We either have to specify by name or by subsystems. (So all
1220 * empty hierarchies must have a name).
1221 */
Paul Menagec6d57f32009-09-23 15:56:19 -07001222 if (!opts->subsys_bits && !opts->name)
Paul Menageddbcc7e2007-10-18 23:39:30 -07001223 return -EINVAL;
1224
Ben Blumcf5d5942010-03-10 15:22:09 -08001225 /*
1226 * Grab references on all the modules we'll need, so the subsystems
1227 * don't dance around before rebind_subsystems attaches them. This may
1228 * take duplicate reference counts on a subsystem that's already used,
1229 * but rebind_subsystems handles this case.
1230 */
1231 for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
1232 unsigned long bit = 1UL << i;
1233
1234 if (!(bit & opts->subsys_bits))
1235 continue;
1236 if (!try_module_get(subsys[i]->module)) {
1237 module_pin_failed = true;
1238 break;
1239 }
1240 }
1241 if (module_pin_failed) {
1242 /*
1243 * oops, one of the modules was going away. this means that we
1244 * raced with a module_delete call, and to the user this is
1245 * essentially a "subsystem doesn't exist" case.
1246 */
1247 for (i--; i >= CGROUP_BUILTIN_SUBSYS_COUNT; i--) {
1248 /* drop refcounts only on the ones we took */
1249 unsigned long bit = 1UL << i;
1250
1251 if (!(bit & opts->subsys_bits))
1252 continue;
1253 module_put(subsys[i]->module);
1254 }
1255 return -ENOENT;
1256 }
1257
Paul Menageddbcc7e2007-10-18 23:39:30 -07001258 return 0;
1259}
1260
Ben Blumcf5d5942010-03-10 15:22:09 -08001261static void drop_parsed_module_refcounts(unsigned long subsys_bits)
1262{
1263 int i;
1264 for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
1265 unsigned long bit = 1UL << i;
1266
1267 if (!(bit & subsys_bits))
1268 continue;
1269 module_put(subsys[i]->module);
1270 }
1271}
1272
Paul Menageddbcc7e2007-10-18 23:39:30 -07001273static int cgroup_remount(struct super_block *sb, int *flags, char *data)
1274{
1275 int ret = 0;
1276 struct cgroupfs_root *root = sb->s_fs_info;
Paul Menagebd89aab2007-10-18 23:40:44 -07001277 struct cgroup *cgrp = &root->top_cgroup;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001278 struct cgroup_sb_opts opts;
1279
Paul Menagebd89aab2007-10-18 23:40:44 -07001280 mutex_lock(&cgrp->dentry->d_inode->i_mutex);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001281 mutex_lock(&cgroup_mutex);
1282
1283 /* See what subsystems are wanted */
1284 ret = parse_cgroupfs_options(data, &opts);
1285 if (ret)
1286 goto out_unlock;
1287
Ben Blumcf5d5942010-03-10 15:22:09 -08001288 /* Don't allow flags or name to change at remount */
1289 if (opts.flags != root->flags ||
1290 (opts.name && strcmp(opts.name, root->name))) {
Paul Menageddbcc7e2007-10-18 23:39:30 -07001291 ret = -EINVAL;
Ben Blumcf5d5942010-03-10 15:22:09 -08001292 drop_parsed_module_refcounts(opts.subsys_bits);
Paul Menagec6d57f32009-09-23 15:56:19 -07001293 goto out_unlock;
1294 }
1295
Paul Menageddbcc7e2007-10-18 23:39:30 -07001296 ret = rebind_subsystems(root, opts.subsys_bits);
Ben Blumcf5d5942010-03-10 15:22:09 -08001297 if (ret) {
1298 drop_parsed_module_refcounts(opts.subsys_bits);
Li Zefan0670e082009-04-02 16:57:30 -07001299 goto out_unlock;
Ben Blumcf5d5942010-03-10 15:22:09 -08001300 }
Paul Menageddbcc7e2007-10-18 23:39:30 -07001301
1302 /* (re)populate subsystem files */
Li Zefan0670e082009-04-02 16:57:30 -07001303 cgroup_populate_dir(cgrp);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001304
Paul Menage81a6a5c2007-10-18 23:39:38 -07001305 if (opts.release_agent)
1306 strcpy(root->release_agent_path, opts.release_agent);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001307 out_unlock:
Jesper Juhl66bdc9c2009-04-02 16:57:27 -07001308 kfree(opts.release_agent);
Paul Menagec6d57f32009-09-23 15:56:19 -07001309 kfree(opts.name);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001310 mutex_unlock(&cgroup_mutex);
Paul Menagebd89aab2007-10-18 23:40:44 -07001311 mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001312 return ret;
1313}
1314
Alexey Dobriyanb87221d2009-09-21 17:01:09 -07001315static const struct super_operations cgroup_ops = {
Paul Menageddbcc7e2007-10-18 23:39:30 -07001316 .statfs = simple_statfs,
1317 .drop_inode = generic_delete_inode,
1318 .show_options = cgroup_show_options,
1319 .remount_fs = cgroup_remount,
1320};
1321
Paul Menagecc31edc2008-10-18 20:28:04 -07001322static void init_cgroup_housekeeping(struct cgroup *cgrp)
1323{
1324 INIT_LIST_HEAD(&cgrp->sibling);
1325 INIT_LIST_HEAD(&cgrp->children);
1326 INIT_LIST_HEAD(&cgrp->css_sets);
1327 INIT_LIST_HEAD(&cgrp->release_list);
Ben Blum72a8cb32009-09-23 15:56:27 -07001328 INIT_LIST_HEAD(&cgrp->pidlists);
1329 mutex_init(&cgrp->pidlist_mutex);
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08001330 INIT_LIST_HEAD(&cgrp->event_list);
1331 spin_lock_init(&cgrp->event_list_lock);
Paul Menagecc31edc2008-10-18 20:28:04 -07001332}
Paul Menagec6d57f32009-09-23 15:56:19 -07001333
Paul Menageddbcc7e2007-10-18 23:39:30 -07001334static void init_cgroup_root(struct cgroupfs_root *root)
1335{
Paul Menagebd89aab2007-10-18 23:40:44 -07001336 struct cgroup *cgrp = &root->top_cgroup;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001337 INIT_LIST_HEAD(&root->subsys_list);
1338 INIT_LIST_HEAD(&root->root_list);
1339 root->number_of_cgroups = 1;
Paul Menagebd89aab2007-10-18 23:40:44 -07001340 cgrp->root = root;
1341 cgrp->top_cgroup = cgrp;
Paul Menagecc31edc2008-10-18 20:28:04 -07001342 init_cgroup_housekeeping(cgrp);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001343}
1344
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001345static bool init_root_id(struct cgroupfs_root *root)
1346{
1347 int ret = 0;
1348
1349 do {
1350 if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL))
1351 return false;
1352 spin_lock(&hierarchy_id_lock);
1353 /* Try to allocate the next unused ID */
1354 ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id,
1355 &root->hierarchy_id);
1356 if (ret == -ENOSPC)
1357 /* Try again starting from 0 */
1358 ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id);
1359 if (!ret) {
1360 next_hierarchy_id = root->hierarchy_id + 1;
1361 } else if (ret != -EAGAIN) {
1362 /* Can only get here if the 31-bit IDR is full ... */
1363 BUG_ON(ret);
1364 }
1365 spin_unlock(&hierarchy_id_lock);
1366 } while (ret);
1367 return true;
1368}
1369
Paul Menageddbcc7e2007-10-18 23:39:30 -07001370static int cgroup_test_super(struct super_block *sb, void *data)
1371{
Paul Menagec6d57f32009-09-23 15:56:19 -07001372 struct cgroup_sb_opts *opts = data;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001373 struct cgroupfs_root *root = sb->s_fs_info;
1374
Paul Menagec6d57f32009-09-23 15:56:19 -07001375 /* If we asked for a name then it must match */
1376 if (opts->name && strcmp(opts->name, root->name))
1377 return 0;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001378
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001379 /*
1380 * If we asked for subsystems (or explicitly for no
1381 * subsystems) then they must match
1382 */
1383 if ((opts->subsys_bits || opts->none)
1384 && (opts->subsys_bits != root->subsys_bits))
Paul Menageddbcc7e2007-10-18 23:39:30 -07001385 return 0;
1386
1387 return 1;
1388}
1389
Paul Menagec6d57f32009-09-23 15:56:19 -07001390static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
1391{
1392 struct cgroupfs_root *root;
1393
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001394 if (!opts->subsys_bits && !opts->none)
Paul Menagec6d57f32009-09-23 15:56:19 -07001395 return NULL;
1396
1397 root = kzalloc(sizeof(*root), GFP_KERNEL);
1398 if (!root)
1399 return ERR_PTR(-ENOMEM);
1400
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001401 if (!init_root_id(root)) {
1402 kfree(root);
1403 return ERR_PTR(-ENOMEM);
1404 }
Paul Menagec6d57f32009-09-23 15:56:19 -07001405 init_cgroup_root(root);
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001406
Paul Menagec6d57f32009-09-23 15:56:19 -07001407 root->subsys_bits = opts->subsys_bits;
1408 root->flags = opts->flags;
1409 if (opts->release_agent)
1410 strcpy(root->release_agent_path, opts->release_agent);
1411 if (opts->name)
1412 strcpy(root->name, opts->name);
Daniel Lezcano97978e62010-10-27 15:33:35 -07001413 if (opts->clone_children)
1414 set_bit(CGRP_CLONE_CHILDREN, &root->top_cgroup.flags);
Paul Menagec6d57f32009-09-23 15:56:19 -07001415 return root;
1416}
1417
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001418static void cgroup_drop_root(struct cgroupfs_root *root)
1419{
1420 if (!root)
1421 return;
1422
1423 BUG_ON(!root->hierarchy_id);
1424 spin_lock(&hierarchy_id_lock);
1425 ida_remove(&hierarchy_ida, root->hierarchy_id);
1426 spin_unlock(&hierarchy_id_lock);
1427 kfree(root);
1428}
1429
Paul Menageddbcc7e2007-10-18 23:39:30 -07001430static int cgroup_set_super(struct super_block *sb, void *data)
1431{
1432 int ret;
Paul Menagec6d57f32009-09-23 15:56:19 -07001433 struct cgroup_sb_opts *opts = data;
1434
1435 /* If we don't have a new root, we can't set up a new sb */
1436 if (!opts->new_root)
1437 return -EINVAL;
1438
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001439 BUG_ON(!opts->subsys_bits && !opts->none);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001440
1441 ret = set_anon_super(sb, NULL);
1442 if (ret)
1443 return ret;
1444
Paul Menagec6d57f32009-09-23 15:56:19 -07001445 sb->s_fs_info = opts->new_root;
1446 opts->new_root->sb = sb;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001447
1448 sb->s_blocksize = PAGE_CACHE_SIZE;
1449 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
1450 sb->s_magic = CGROUP_SUPER_MAGIC;
1451 sb->s_op = &cgroup_ops;
1452
1453 return 0;
1454}
1455
1456static int cgroup_get_rootdir(struct super_block *sb)
1457{
Al Viro0df6a632010-12-21 13:29:29 -05001458 static const struct dentry_operations cgroup_dops = {
1459 .d_iput = cgroup_diput,
Al Viroc72a04e2011-01-14 05:31:45 +00001460 .d_delete = cgroup_delete,
Al Viro0df6a632010-12-21 13:29:29 -05001461 };
1462
Paul Menageddbcc7e2007-10-18 23:39:30 -07001463 struct inode *inode =
1464 cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb);
1465 struct dentry *dentry;
1466
1467 if (!inode)
1468 return -ENOMEM;
1469
Paul Menageddbcc7e2007-10-18 23:39:30 -07001470 inode->i_fop = &simple_dir_operations;
1471 inode->i_op = &cgroup_dir_inode_operations;
1472 /* directories start off with i_nlink == 2 (for "." entry) */
1473 inc_nlink(inode);
1474 dentry = d_alloc_root(inode);
1475 if (!dentry) {
1476 iput(inode);
1477 return -ENOMEM;
1478 }
1479 sb->s_root = dentry;
Al Viro0df6a632010-12-21 13:29:29 -05001480 /* for everything else we want ->d_op set */
1481 sb->s_d_op = &cgroup_dops;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001482 return 0;
1483}
1484
Al Virof7e83572010-07-26 13:23:11 +04001485static struct dentry *cgroup_mount(struct file_system_type *fs_type,
Paul Menageddbcc7e2007-10-18 23:39:30 -07001486 int flags, const char *unused_dev_name,
Al Virof7e83572010-07-26 13:23:11 +04001487 void *data)
Paul Menageddbcc7e2007-10-18 23:39:30 -07001488{
1489 struct cgroup_sb_opts opts;
Paul Menagec6d57f32009-09-23 15:56:19 -07001490 struct cgroupfs_root *root;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001491 int ret = 0;
1492 struct super_block *sb;
Paul Menagec6d57f32009-09-23 15:56:19 -07001493 struct cgroupfs_root *new_root;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001494
1495 /* First find the desired set of subsystems */
Ben Blumaae8aab2010-03-10 15:22:07 -08001496 mutex_lock(&cgroup_mutex);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001497 ret = parse_cgroupfs_options(data, &opts);
Ben Blumaae8aab2010-03-10 15:22:07 -08001498 mutex_unlock(&cgroup_mutex);
Paul Menagec6d57f32009-09-23 15:56:19 -07001499 if (ret)
1500 goto out_err;
1501
1502 /*
1503 * Allocate a new cgroup root. We may not need it if we're
1504 * reusing an existing hierarchy.
1505 */
1506 new_root = cgroup_root_from_opts(&opts);
1507 if (IS_ERR(new_root)) {
1508 ret = PTR_ERR(new_root);
Ben Blumcf5d5942010-03-10 15:22:09 -08001509 goto drop_modules;
Paul Menage81a6a5c2007-10-18 23:39:38 -07001510 }
Paul Menagec6d57f32009-09-23 15:56:19 -07001511 opts.new_root = new_root;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001512
Paul Menagec6d57f32009-09-23 15:56:19 -07001513 /* Locate an existing or new sb for this hierarchy */
1514 sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001515 if (IS_ERR(sb)) {
Paul Menagec6d57f32009-09-23 15:56:19 -07001516 ret = PTR_ERR(sb);
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001517 cgroup_drop_root(opts.new_root);
Ben Blumcf5d5942010-03-10 15:22:09 -08001518 goto drop_modules;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001519 }
1520
Paul Menagec6d57f32009-09-23 15:56:19 -07001521 root = sb->s_fs_info;
1522 BUG_ON(!root);
1523 if (root == opts.new_root) {
1524 /* We used the new root structure, so this is a new hierarchy */
1525 struct list_head tmp_cg_links;
Li Zefanc12f65d2009-01-07 18:07:42 -08001526 struct cgroup *root_cgrp = &root->top_cgroup;
Paul Menage817929e2007-10-18 23:39:36 -07001527 struct inode *inode;
Paul Menagec6d57f32009-09-23 15:56:19 -07001528 struct cgroupfs_root *existing_root;
Li Zefan28fd5df2008-04-29 01:00:13 -07001529 int i;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001530
1531 BUG_ON(sb->s_root != NULL);
1532
1533 ret = cgroup_get_rootdir(sb);
1534 if (ret)
1535 goto drop_new_super;
Paul Menage817929e2007-10-18 23:39:36 -07001536 inode = sb->s_root->d_inode;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001537
Paul Menage817929e2007-10-18 23:39:36 -07001538 mutex_lock(&inode->i_mutex);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001539 mutex_lock(&cgroup_mutex);
1540
Paul Menagec6d57f32009-09-23 15:56:19 -07001541 if (strlen(root->name)) {
1542 /* Check for name clashes with existing mounts */
1543 for_each_active_root(existing_root) {
1544 if (!strcmp(existing_root->name, root->name)) {
1545 ret = -EBUSY;
1546 mutex_unlock(&cgroup_mutex);
1547 mutex_unlock(&inode->i_mutex);
1548 goto drop_new_super;
1549 }
1550 }
1551 }
1552
Paul Menage817929e2007-10-18 23:39:36 -07001553 /*
1554 * We're accessing css_set_count without locking
1555 * css_set_lock here, but that's OK - it can only be
1556 * increased by someone holding cgroup_lock, and
1557 * that's us. The worst that can happen is that we
1558 * have some link structures left over
1559 */
1560 ret = allocate_cg_links(css_set_count, &tmp_cg_links);
1561 if (ret) {
1562 mutex_unlock(&cgroup_mutex);
1563 mutex_unlock(&inode->i_mutex);
1564 goto drop_new_super;
1565 }
1566
Paul Menageddbcc7e2007-10-18 23:39:30 -07001567 ret = rebind_subsystems(root, root->subsys_bits);
1568 if (ret == -EBUSY) {
1569 mutex_unlock(&cgroup_mutex);
Paul Menage817929e2007-10-18 23:39:36 -07001570 mutex_unlock(&inode->i_mutex);
Paul Menagec6d57f32009-09-23 15:56:19 -07001571 free_cg_links(&tmp_cg_links);
1572 goto drop_new_super;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001573 }
Ben Blumcf5d5942010-03-10 15:22:09 -08001574 /*
1575 * There must be no failure case after here, since rebinding
1576 * takes care of subsystems' refcounts, which are explicitly
1577 * dropped in the failure exit path.
1578 */
Paul Menageddbcc7e2007-10-18 23:39:30 -07001579
1580 /* EBUSY should be the only error here */
1581 BUG_ON(ret);
1582
1583 list_add(&root->root_list, &roots);
Paul Menage817929e2007-10-18 23:39:36 -07001584 root_count++;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001585
Li Zefanc12f65d2009-01-07 18:07:42 -08001586 sb->s_root->d_fsdata = root_cgrp;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001587 root->top_cgroup.dentry = sb->s_root;
1588
Paul Menage817929e2007-10-18 23:39:36 -07001589 /* Link the top cgroup in this hierarchy into all
1590 * the css_set objects */
1591 write_lock(&css_set_lock);
Li Zefan28fd5df2008-04-29 01:00:13 -07001592 for (i = 0; i < CSS_SET_TABLE_SIZE; i++) {
1593 struct hlist_head *hhead = &css_set_table[i];
1594 struct hlist_node *node;
Paul Menage817929e2007-10-18 23:39:36 -07001595 struct css_set *cg;
Li Zefan28fd5df2008-04-29 01:00:13 -07001596
Li Zefanc12f65d2009-01-07 18:07:42 -08001597 hlist_for_each_entry(cg, node, hhead, hlist)
1598 link_css_set(&tmp_cg_links, cg, root_cgrp);
Li Zefan28fd5df2008-04-29 01:00:13 -07001599 }
Paul Menage817929e2007-10-18 23:39:36 -07001600 write_unlock(&css_set_lock);
1601
1602 free_cg_links(&tmp_cg_links);
1603
Li Zefanc12f65d2009-01-07 18:07:42 -08001604 BUG_ON(!list_empty(&root_cgrp->sibling));
1605 BUG_ON(!list_empty(&root_cgrp->children));
Paul Menageddbcc7e2007-10-18 23:39:30 -07001606 BUG_ON(root->number_of_cgroups != 1);
1607
Li Zefanc12f65d2009-01-07 18:07:42 -08001608 cgroup_populate_dir(root_cgrp);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001609 mutex_unlock(&cgroup_mutex);
Xiaotian Feng34f77a92009-09-23 15:56:18 -07001610 mutex_unlock(&inode->i_mutex);
Paul Menagec6d57f32009-09-23 15:56:19 -07001611 } else {
1612 /*
1613 * We re-used an existing hierarchy - the new root (if
1614 * any) is not needed
1615 */
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001616 cgroup_drop_root(opts.new_root);
Ben Blumcf5d5942010-03-10 15:22:09 -08001617 /* no subsys rebinding, so refcounts don't change */
1618 drop_parsed_module_refcounts(opts.subsys_bits);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001619 }
1620
Paul Menagec6d57f32009-09-23 15:56:19 -07001621 kfree(opts.release_agent);
1622 kfree(opts.name);
Al Virof7e83572010-07-26 13:23:11 +04001623 return dget(sb->s_root);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001624
1625 drop_new_super:
Al Viro6f5bbff2009-05-06 01:34:22 -04001626 deactivate_locked_super(sb);
Ben Blumcf5d5942010-03-10 15:22:09 -08001627 drop_modules:
1628 drop_parsed_module_refcounts(opts.subsys_bits);
Paul Menagec6d57f32009-09-23 15:56:19 -07001629 out_err:
1630 kfree(opts.release_agent);
1631 kfree(opts.name);
Al Virof7e83572010-07-26 13:23:11 +04001632 return ERR_PTR(ret);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001633}
1634
1635static void cgroup_kill_sb(struct super_block *sb) {
1636 struct cgroupfs_root *root = sb->s_fs_info;
Paul Menagebd89aab2007-10-18 23:40:44 -07001637 struct cgroup *cgrp = &root->top_cgroup;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001638 int ret;
KOSAKI Motohiro71cbb942008-07-25 01:46:55 -07001639 struct cg_cgroup_link *link;
1640 struct cg_cgroup_link *saved_link;
Paul Menageddbcc7e2007-10-18 23:39:30 -07001641
1642 BUG_ON(!root);
1643
1644 BUG_ON(root->number_of_cgroups != 1);
Paul Menagebd89aab2007-10-18 23:40:44 -07001645 BUG_ON(!list_empty(&cgrp->children));
1646 BUG_ON(!list_empty(&cgrp->sibling));
Paul Menageddbcc7e2007-10-18 23:39:30 -07001647
1648 mutex_lock(&cgroup_mutex);
1649
1650 /* Rebind all subsystems back to the default hierarchy */
1651 ret = rebind_subsystems(root, 0);
1652 /* Shouldn't be able to fail ... */
1653 BUG_ON(ret);
1654
Paul Menage817929e2007-10-18 23:39:36 -07001655 /*
1656 * Release all the links from css_sets to this hierarchy's
1657 * root cgroup
1658 */
1659 write_lock(&css_set_lock);
KOSAKI Motohiro71cbb942008-07-25 01:46:55 -07001660
1661 list_for_each_entry_safe(link, saved_link, &cgrp->css_sets,
1662 cgrp_link_list) {
Paul Menage817929e2007-10-18 23:39:36 -07001663 list_del(&link->cg_link_list);
Paul Menagebd89aab2007-10-18 23:40:44 -07001664 list_del(&link->cgrp_link_list);
Paul Menage817929e2007-10-18 23:39:36 -07001665 kfree(link);
1666 }
1667 write_unlock(&css_set_lock);
1668
Paul Menage839ec542009-01-29 14:25:22 -08001669 if (!list_empty(&root->root_list)) {
1670 list_del(&root->root_list);
1671 root_count--;
1672 }
Li Zefane5f6a862009-01-07 18:07:41 -08001673
Paul Menageddbcc7e2007-10-18 23:39:30 -07001674 mutex_unlock(&cgroup_mutex);
1675
Paul Menageddbcc7e2007-10-18 23:39:30 -07001676 kill_litter_super(sb);
Paul Menage2c6ab6d2009-09-23 15:56:23 -07001677 cgroup_drop_root(root);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001678}
1679
1680static struct file_system_type cgroup_fs_type = {
1681 .name = "cgroup",
Al Virof7e83572010-07-26 13:23:11 +04001682 .mount = cgroup_mount,
Paul Menageddbcc7e2007-10-18 23:39:30 -07001683 .kill_sb = cgroup_kill_sb,
1684};
1685
Greg KH676db4a2010-08-05 13:53:35 -07001686static struct kobject *cgroup_kobj;
1687
Paul Menagebd89aab2007-10-18 23:40:44 -07001688static inline struct cgroup *__d_cgrp(struct dentry *dentry)
Paul Menageddbcc7e2007-10-18 23:39:30 -07001689{
1690 return dentry->d_fsdata;
1691}
1692
1693static inline struct cftype *__d_cft(struct dentry *dentry)
1694{
1695 return dentry->d_fsdata;
1696}
1697
Li Zefana043e3b2008-02-23 15:24:09 -08001698/**
1699 * cgroup_path - generate the path of a cgroup
1700 * @cgrp: the cgroup in question
1701 * @buf: the buffer to write the path into
1702 * @buflen: the length of the buffer
1703 *
Paul Menagea47295e2009-01-07 18:07:44 -08001704 * Called with cgroup_mutex held or else with an RCU-protected cgroup
1705 * reference. Writes path of cgroup into buf. Returns 0 on success,
1706 * -errno on error.
Paul Menageddbcc7e2007-10-18 23:39:30 -07001707 */
Paul Menagebd89aab2007-10-18 23:40:44 -07001708int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
Paul Menageddbcc7e2007-10-18 23:39:30 -07001709{
1710 char *start;
Li Zefan9a9686b2010-04-22 17:29:24 +08001711 struct dentry *dentry = rcu_dereference_check(cgrp->dentry,
1712 rcu_read_lock_held() ||
1713 cgroup_lock_is_held());
Paul Menageddbcc7e2007-10-18 23:39:30 -07001714
Paul Menagea47295e2009-01-07 18:07:44 -08001715 if (!dentry || cgrp == dummytop) {
Paul Menageddbcc7e2007-10-18 23:39:30 -07001716 /*
1717 * Inactive subsystems have no dentry for their root
1718 * cgroup
1719 */
1720 strcpy(buf, "/");
1721 return 0;
1722 }
1723
1724 start = buf + buflen;
1725
1726 *--start = '\0';
1727 for (;;) {
Paul Menagea47295e2009-01-07 18:07:44 -08001728 int len = dentry->d_name.len;
Li Zefan9a9686b2010-04-22 17:29:24 +08001729
Paul Menageddbcc7e2007-10-18 23:39:30 -07001730 if ((start -= len) < buf)
1731 return -ENAMETOOLONG;
Li Zefan9a9686b2010-04-22 17:29:24 +08001732 memcpy(start, dentry->d_name.name, len);
Paul Menagebd89aab2007-10-18 23:40:44 -07001733 cgrp = cgrp->parent;
1734 if (!cgrp)
Paul Menageddbcc7e2007-10-18 23:39:30 -07001735 break;
Li Zefan9a9686b2010-04-22 17:29:24 +08001736
1737 dentry = rcu_dereference_check(cgrp->dentry,
1738 rcu_read_lock_held() ||
1739 cgroup_lock_is_held());
Paul Menagebd89aab2007-10-18 23:40:44 -07001740 if (!cgrp->parent)
Paul Menageddbcc7e2007-10-18 23:39:30 -07001741 continue;
1742 if (--start < buf)
1743 return -ENAMETOOLONG;
1744 *start = '/';
1745 }
1746 memmove(buf, start, buf + buflen - start);
1747 return 0;
1748}
Ben Blum67523c42010-03-10 15:22:11 -08001749EXPORT_SYMBOL_GPL(cgroup_path);
Paul Menageddbcc7e2007-10-18 23:39:30 -07001750
Li Zefana043e3b2008-02-23 15:24:09 -08001751/**
1752 * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp'
1753 * @cgrp: the cgroup the task is attaching to
1754 * @tsk: the task to be attached
Paul Menagebbcb81d2007-10-18 23:39:32 -07001755 *
Li Zefana043e3b2008-02-23 15:24:09 -08001756 * Call holding cgroup_mutex. May take task_lock of
1757 * the task 'tsk' during call.
Paul Menagebbcb81d2007-10-18 23:39:32 -07001758 */
Cliff Wickman956db3c2008-02-07 00:14:43 -08001759int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
Paul Menagebbcb81d2007-10-18 23:39:32 -07001760{
1761 int retval = 0;
Daisuke Nishimura2468c722010-03-10 15:22:03 -08001762 struct cgroup_subsys *ss, *failed_ss = NULL;
Paul Menagebd89aab2007-10-18 23:40:44 -07001763 struct cgroup *oldcgrp;
Lai Jiangshan77efecd2009-01-07 18:07:39 -08001764 struct css_set *cg;
Paul Menage817929e2007-10-18 23:39:36 -07001765 struct css_set *newcg;
Paul Menagebd89aab2007-10-18 23:40:44 -07001766 struct cgroupfs_root *root = cgrp->root;
Paul Menagebbcb81d2007-10-18 23:39:32 -07001767
1768 /* Nothing to do if the task is already in that cgroup */
Paul Menage7717f7b2009-09-23 15:56:22 -07001769 oldcgrp = task_cgroup_from_root(tsk, root);
Paul Menagebd89aab2007-10-18 23:40:44 -07001770 if (cgrp == oldcgrp)
Paul Menagebbcb81d2007-10-18 23:39:32 -07001771 return 0;
1772
1773 for_each_subsys(root, ss) {
1774 if (ss->can_attach) {
Ben Blumbe367d02009-09-23 15:56:31 -07001775 retval = ss->can_attach(ss, cgrp, tsk, false);
Daisuke Nishimura2468c722010-03-10 15:22:03 -08001776 if (retval) {
1777 /*
1778 * Remember on which subsystem the can_attach()
1779 * failed, so that we only call cancel_attach()
1780 * against the subsystems whose can_attach()
1781 * succeeded. (See below)
1782 */
1783 failed_ss = ss;
1784 goto out;
1785 }
Paul Menagebbcb81d2007-10-18 23:39:32 -07001786 }
1787 }
1788
Lai Jiangshan77efecd2009-01-07 18:07:39 -08001789 task_lock(tsk);
1790 cg = tsk->cgroups;
1791 get_css_set(cg);
1792 task_unlock(tsk);
Paul Menage817929e2007-10-18 23:39:36 -07001793 /*
1794 * Locate or allocate a new css_set for this task,
1795 * based on its final set of cgroups
1796 */
Paul Menagebd89aab2007-10-18 23:40:44 -07001797 newcg = find_css_set(cg, cgrp);
Lai Jiangshan77efecd2009-01-07 18:07:39 -08001798 put_css_set(cg);
Daisuke Nishimura2468c722010-03-10 15:22:03 -08001799 if (!newcg) {
1800 retval = -ENOMEM;
1801 goto out;
1802 }
Paul Menage817929e2007-10-18 23:39:36 -07001803
Paul Menagebbcb81d2007-10-18 23:39:32 -07001804 task_lock(tsk);
1805 if (tsk->flags & PF_EXITING) {
1806 task_unlock(tsk);
Paul Menage817929e2007-10-18 23:39:36 -07001807 put_css_set(newcg);
Daisuke Nishimura2468c722010-03-10 15:22:03 -08001808 retval = -ESRCH;
1809 goto out;
Paul Menagebbcb81d2007-10-18 23:39:32 -07001810 }
Paul Menage817929e2007-10-18 23:39:36 -07001811 rcu_assign_pointer(tsk->cgroups, newcg);
Paul Menagebbcb81d2007-10-18 23:39:32 -07001812 task_unlock(tsk);
1813
Paul Menage817929e2007-10-18 23:39:36 -07001814 /* Update the css_set linked lists if we're using them */
1815 write_lock(&css_set_lock);
1816 if (!list_empty(&tsk->cg_list)) {
1817 list_del(&tsk->cg_list);
1818 list_add(&tsk->cg_list, &newcg->tasks);
1819 }
1820 write_unlock(&css_set_lock);
1821
Paul Menagebbcb81d2007-10-18 23:39:32 -07001822 for_each_subsys(root, ss) {
Paul Jacksone18f6312008-02-07 00:13:44 -08001823 if (ss->attach)
Ben Blumbe367d02009-09-23 15:56:31 -07001824 ss->attach(ss, cgrp, oldcgrp, tsk, false);
Paul Menagebbcb81d2007-10-18 23:39:32 -07001825 }
Paul Menagebd89aab2007-10-18 23:40:44 -07001826 set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
Paul Menagebbcb81d2007-10-18 23:39:32 -07001827 synchronize_rcu();
Paul Menage817929e2007-10-18 23:39:36 -07001828 put_css_set(cg);
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07001829
1830 /*
1831 * wake up rmdir() waiter. the rmdir should fail since the cgroup
1832 * is no longer empty.
1833 */
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -07001834 cgroup_wakeup_rmdir_waiter(cgrp);
Daisuke Nishimura2468c722010-03-10 15:22:03 -08001835out:
1836 if (retval) {
1837 for_each_subsys(root, ss) {
1838 if (ss == failed_ss)
1839 /*
1840 * This subsystem was the one that failed the
1841 * can_attach() check earlier, so we don't need
1842 * to call cancel_attach() against it or any
1843 * remaining subsystems.
1844 */
1845 break;
1846 if (ss->cancel_attach)
1847 ss->cancel_attach(ss, cgrp, tsk, false);
1848 }
1849 }
1850 return retval;
Paul Menagebbcb81d2007-10-18 23:39:32 -07001851}
1852
Sridhar Samudralad7926ee2010-05-30 22:24:39 +02001853/**
Michael S. Tsirkin31583bb2010-09-09 16:37:37 -07001854 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
1855 * @from: attach to all cgroups of a given task
Sridhar Samudralad7926ee2010-05-30 22:24:39 +02001856 * @tsk: the task to be attached
1857 */
Michael S. Tsirkin31583bb2010-09-09 16:37:37 -07001858int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
Sridhar Samudralad7926ee2010-05-30 22:24:39 +02001859{
1860 struct cgroupfs_root *root;
Sridhar Samudralad7926ee2010-05-30 22:24:39 +02001861 int retval = 0;
1862
1863 cgroup_lock();
1864 for_each_active_root(root) {
Michael S. Tsirkin31583bb2010-09-09 16:37:37 -07001865 struct cgroup *from_cg = task_cgroup_from_root(from, root);
1866
1867 retval = cgroup_attach_task(from_cg, tsk);
Sridhar Samudralad7926ee2010-05-30 22:24:39 +02001868 if (retval)
1869 break;
1870 }
1871 cgroup_unlock();
1872
1873 return retval;
1874}
Michael S. Tsirkin31583bb2010-09-09 16:37:37 -07001875EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
Sridhar Samudralad7926ee2010-05-30 22:24:39 +02001876
Paul Menagebbcb81d2007-10-18 23:39:32 -07001877/*
Paul Menageaf351022008-07-25 01:47:01 -07001878 * Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex
1879 * held. May take task_lock of task
Paul Menagebbcb81d2007-10-18 23:39:32 -07001880 */
Paul Menageaf351022008-07-25 01:47:01 -07001881static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
Paul Menagebbcb81d2007-10-18 23:39:32 -07001882{
Paul Menagebbcb81d2007-10-18 23:39:32 -07001883 struct task_struct *tsk;
David Howellsc69e8d92008-11-14 10:39:19 +11001884 const struct cred *cred = current_cred(), *tcred;
Paul Menagebbcb81d2007-10-18 23:39:32 -07001885 int ret;
1886
Paul Menagebbcb81d2007-10-18 23:39:32 -07001887 if (pid) {
1888 rcu_read_lock();
Pavel Emelyanov73507f32008-02-07 00:14:47 -08001889 tsk = find_task_by_vpid(pid);
Paul Menagebbcb81d2007-10-18 23:39:32 -07001890 if (!tsk || tsk->flags & PF_EXITING) {
1891 rcu_read_unlock();
1892 return -ESRCH;
1893 }
Paul Menagebbcb81d2007-10-18 23:39:32 -07001894
David Howellsc69e8d92008-11-14 10:39:19 +11001895 tcred = __task_cred(tsk);
1896 if (cred->euid &&
1897 cred->euid != tcred->uid &&
1898 cred->euid != tcred->suid) {
1899 rcu_read_unlock();
Paul Menagebbcb81d2007-10-18 23:39:32 -07001900 return -EACCES;
1901 }
David Howellsc69e8d92008-11-14 10:39:19 +11001902 get_task_struct(tsk);
1903 rcu_read_unlock();
Paul Menagebbcb81d2007-10-18 23:39:32 -07001904 } else {
1905 tsk = current;
1906 get_task_struct(tsk);
1907 }
1908
Cliff Wickman956db3c2008-02-07 00:14:43 -08001909 ret = cgroup_attach_task(cgrp, tsk);
Paul Menagebbcb81d2007-10-18 23:39:32 -07001910 put_task_struct(tsk);
1911 return ret;
1912}
1913
Paul Menageaf351022008-07-25 01:47:01 -07001914static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid)
1915{
1916 int ret;
1917 if (!cgroup_lock_live_group(cgrp))
1918 return -ENODEV;
1919 ret = attach_task_by_pid(cgrp, pid);
1920 cgroup_unlock();
1921 return ret;
1922}
1923
Paul Menagee788e062008-07-25 01:46:59 -07001924/**
1925 * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
1926 * @cgrp: the cgroup to be checked for liveness
1927 *
Paul Menage84eea842008-07-25 01:47:00 -07001928 * On success, returns true; the lock should be later released with
1929 * cgroup_unlock(). On failure returns false with no lock held.
Paul Menagee788e062008-07-25 01:46:59 -07001930 */
Paul Menage84eea842008-07-25 01:47:00 -07001931bool cgroup_lock_live_group(struct cgroup *cgrp)
Paul Menagee788e062008-07-25 01:46:59 -07001932{
1933 mutex_lock(&cgroup_mutex);
1934 if (cgroup_is_removed(cgrp)) {
1935 mutex_unlock(&cgroup_mutex);
1936 return false;
1937 }
1938 return true;
1939}
Ben Blum67523c42010-03-10 15:22:11 -08001940EXPORT_SYMBOL_GPL(cgroup_lock_live_group);
Paul Menagee788e062008-07-25 01:46:59 -07001941
1942static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft,
1943 const char *buffer)
1944{
1945 BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
Evgeny Kuznetsovf4a25892010-10-27 15:33:37 -07001946 if (strlen(buffer) >= PATH_MAX)
1947 return -EINVAL;
Paul Menagee788e062008-07-25 01:46:59 -07001948 if (!cgroup_lock_live_group(cgrp))
1949 return -ENODEV;
1950 strcpy(cgrp->root->release_agent_path, buffer);
Paul Menage84eea842008-07-25 01:47:00 -07001951 cgroup_unlock();
Paul Menagee788e062008-07-25 01:46:59 -07001952 return 0;
1953}
1954
1955static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft,
1956 struct seq_file *seq)
1957{
1958 if (!cgroup_lock_live_group(cgrp))
1959 return -ENODEV;
1960 seq_puts(seq, cgrp->root->release_agent_path);
1961 seq_putc(seq, '\n');
Paul Menage84eea842008-07-25 01:47:00 -07001962 cgroup_unlock();
Paul Menagee788e062008-07-25 01:46:59 -07001963 return 0;
1964}
1965
Paul Menage84eea842008-07-25 01:47:00 -07001966/* A buffer size big enough for numbers or short strings */
1967#define CGROUP_LOCAL_BUFFER_SIZE 64
1968
Paul Menagee73d2c62008-04-29 01:00:06 -07001969static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft,
Paul Menagef4c753b2008-04-29 00:59:56 -07001970 struct file *file,
1971 const char __user *userbuf,
1972 size_t nbytes, loff_t *unused_ppos)
Paul Menage355e0c42007-10-18 23:39:33 -07001973{
Paul Menage84eea842008-07-25 01:47:00 -07001974 char buffer[CGROUP_LOCAL_BUFFER_SIZE];
Paul Menage355e0c42007-10-18 23:39:33 -07001975 int retval = 0;
Paul Menage355e0c42007-10-18 23:39:33 -07001976 char *end;
1977
1978 if (!nbytes)
1979 return -EINVAL;
1980 if (nbytes >= sizeof(buffer))
1981 return -E2BIG;
1982 if (copy_from_user(buffer, userbuf, nbytes))
1983 return -EFAULT;
1984
1985 buffer[nbytes] = 0; /* nul-terminate */
Paul Menagee73d2c62008-04-29 01:00:06 -07001986 if (cft->write_u64) {
KOSAKI Motohiro478988d2009-10-26 16:49:36 -07001987 u64 val = simple_strtoull(strstrip(buffer), &end, 0);
Paul Menagee73d2c62008-04-29 01:00:06 -07001988 if (*end)
1989 return -EINVAL;
1990 retval = cft->write_u64(cgrp, cft, val);
1991 } else {
KOSAKI Motohiro478988d2009-10-26 16:49:36 -07001992 s64 val = simple_strtoll(strstrip(buffer), &end, 0);
Paul Menagee73d2c62008-04-29 01:00:06 -07001993 if (*end)
1994 return -EINVAL;
1995 retval = cft->write_s64(cgrp, cft, val);
1996 }
Paul Menage355e0c42007-10-18 23:39:33 -07001997 if (!retval)
1998 retval = nbytes;
1999 return retval;
2000}
2001
Paul Menagedb3b1492008-07-25 01:46:58 -07002002static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft,
2003 struct file *file,
2004 const char __user *userbuf,
2005 size_t nbytes, loff_t *unused_ppos)
2006{
Paul Menage84eea842008-07-25 01:47:00 -07002007 char local_buffer[CGROUP_LOCAL_BUFFER_SIZE];
Paul Menagedb3b1492008-07-25 01:46:58 -07002008 int retval = 0;
2009 size_t max_bytes = cft->max_write_len;
2010 char *buffer = local_buffer;
2011
2012 if (!max_bytes)
2013 max_bytes = sizeof(local_buffer) - 1;
2014 if (nbytes >= max_bytes)
2015 return -E2BIG;
2016 /* Allocate a dynamic buffer if we need one */
2017 if (nbytes >= sizeof(local_buffer)) {
2018 buffer = kmalloc(nbytes + 1, GFP_KERNEL);
2019 if (buffer == NULL)
2020 return -ENOMEM;
2021 }
Li Zefan5a3eb9f2008-07-29 22:33:18 -07002022 if (nbytes && copy_from_user(buffer, userbuf, nbytes)) {
2023 retval = -EFAULT;
2024 goto out;
2025 }
Paul Menagedb3b1492008-07-25 01:46:58 -07002026
2027 buffer[nbytes] = 0; /* nul-terminate */
KOSAKI Motohiro478988d2009-10-26 16:49:36 -07002028 retval = cft->write_string(cgrp, cft, strstrip(buffer));
Paul Menagedb3b1492008-07-25 01:46:58 -07002029 if (!retval)
2030 retval = nbytes;
Li Zefan5a3eb9f2008-07-29 22:33:18 -07002031out:
Paul Menagedb3b1492008-07-25 01:46:58 -07002032 if (buffer != local_buffer)
2033 kfree(buffer);
2034 return retval;
2035}
2036
Paul Menageddbcc7e2007-10-18 23:39:30 -07002037static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
2038 size_t nbytes, loff_t *ppos)
2039{
2040 struct cftype *cft = __d_cft(file->f_dentry);
Paul Menagebd89aab2007-10-18 23:40:44 -07002041 struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002042
Li Zefan75139b82009-01-07 18:07:33 -08002043 if (cgroup_is_removed(cgrp))
Paul Menageddbcc7e2007-10-18 23:39:30 -07002044 return -ENODEV;
Paul Menage355e0c42007-10-18 23:39:33 -07002045 if (cft->write)
Paul Menagebd89aab2007-10-18 23:40:44 -07002046 return cft->write(cgrp, cft, file, buf, nbytes, ppos);
Paul Menagee73d2c62008-04-29 01:00:06 -07002047 if (cft->write_u64 || cft->write_s64)
2048 return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos);
Paul Menagedb3b1492008-07-25 01:46:58 -07002049 if (cft->write_string)
2050 return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos);
Pavel Emelyanovd447ea22008-04-29 01:00:08 -07002051 if (cft->trigger) {
2052 int ret = cft->trigger(cgrp, (unsigned int)cft->private);
2053 return ret ? ret : nbytes;
2054 }
Paul Menage355e0c42007-10-18 23:39:33 -07002055 return -EINVAL;
Paul Menageddbcc7e2007-10-18 23:39:30 -07002056}
2057
Paul Menagef4c753b2008-04-29 00:59:56 -07002058static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft,
2059 struct file *file,
2060 char __user *buf, size_t nbytes,
2061 loff_t *ppos)
Paul Menageddbcc7e2007-10-18 23:39:30 -07002062{
Paul Menage84eea842008-07-25 01:47:00 -07002063 char tmp[CGROUP_LOCAL_BUFFER_SIZE];
Paul Menagef4c753b2008-04-29 00:59:56 -07002064 u64 val = cft->read_u64(cgrp, cft);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002065 int len = sprintf(tmp, "%llu\n", (unsigned long long) val);
2066
2067 return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
2068}
2069
Paul Menagee73d2c62008-04-29 01:00:06 -07002070static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft,
2071 struct file *file,
2072 char __user *buf, size_t nbytes,
2073 loff_t *ppos)
2074{
Paul Menage84eea842008-07-25 01:47:00 -07002075 char tmp[CGROUP_LOCAL_BUFFER_SIZE];
Paul Menagee73d2c62008-04-29 01:00:06 -07002076 s64 val = cft->read_s64(cgrp, cft);
2077 int len = sprintf(tmp, "%lld\n", (long long) val);
2078
2079 return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
2080}
2081
Paul Menageddbcc7e2007-10-18 23:39:30 -07002082static ssize_t cgroup_file_read(struct file *file, char __user *buf,
2083 size_t nbytes, loff_t *ppos)
2084{
2085 struct cftype *cft = __d_cft(file->f_dentry);
Paul Menagebd89aab2007-10-18 23:40:44 -07002086 struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002087
Li Zefan75139b82009-01-07 18:07:33 -08002088 if (cgroup_is_removed(cgrp))
Paul Menageddbcc7e2007-10-18 23:39:30 -07002089 return -ENODEV;
2090
2091 if (cft->read)
Paul Menagebd89aab2007-10-18 23:40:44 -07002092 return cft->read(cgrp, cft, file, buf, nbytes, ppos);
Paul Menagef4c753b2008-04-29 00:59:56 -07002093 if (cft->read_u64)
2094 return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos);
Paul Menagee73d2c62008-04-29 01:00:06 -07002095 if (cft->read_s64)
2096 return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002097 return -EINVAL;
2098}
2099
Paul Menage91796562008-04-29 01:00:01 -07002100/*
2101 * seqfile ops/methods for returning structured data. Currently just
2102 * supports string->u64 maps, but can be extended in future.
2103 */
2104
2105struct cgroup_seqfile_state {
2106 struct cftype *cft;
2107 struct cgroup *cgroup;
2108};
2109
2110static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value)
2111{
2112 struct seq_file *sf = cb->state;
2113 return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value);
2114}
2115
2116static int cgroup_seqfile_show(struct seq_file *m, void *arg)
2117{
2118 struct cgroup_seqfile_state *state = m->private;
2119 struct cftype *cft = state->cft;
Serge E. Hallyn29486df2008-04-29 01:00:14 -07002120 if (cft->read_map) {
2121 struct cgroup_map_cb cb = {
2122 .fill = cgroup_map_add,
2123 .state = m,
2124 };
2125 return cft->read_map(state->cgroup, cft, &cb);
2126 }
2127 return cft->read_seq_string(state->cgroup, cft, m);
Paul Menage91796562008-04-29 01:00:01 -07002128}
2129
Adrian Bunk96930a62008-07-25 19:46:21 -07002130static int cgroup_seqfile_release(struct inode *inode, struct file *file)
Paul Menage91796562008-04-29 01:00:01 -07002131{
2132 struct seq_file *seq = file->private_data;
2133 kfree(seq->private);
2134 return single_release(inode, file);
2135}
2136
Alexey Dobriyan828c0952009-10-01 15:43:56 -07002137static const struct file_operations cgroup_seqfile_operations = {
Paul Menage91796562008-04-29 01:00:01 -07002138 .read = seq_read,
Paul Menagee788e062008-07-25 01:46:59 -07002139 .write = cgroup_file_write,
Paul Menage91796562008-04-29 01:00:01 -07002140 .llseek = seq_lseek,
2141 .release = cgroup_seqfile_release,
2142};
2143
Paul Menageddbcc7e2007-10-18 23:39:30 -07002144static int cgroup_file_open(struct inode *inode, struct file *file)
2145{
2146 int err;
2147 struct cftype *cft;
2148
2149 err = generic_file_open(inode, file);
2150 if (err)
2151 return err;
Paul Menageddbcc7e2007-10-18 23:39:30 -07002152 cft = __d_cft(file->f_dentry);
Li Zefan75139b82009-01-07 18:07:33 -08002153
Serge E. Hallyn29486df2008-04-29 01:00:14 -07002154 if (cft->read_map || cft->read_seq_string) {
Paul Menage91796562008-04-29 01:00:01 -07002155 struct cgroup_seqfile_state *state =
2156 kzalloc(sizeof(*state), GFP_USER);
2157 if (!state)
2158 return -ENOMEM;
2159 state->cft = cft;
2160 state->cgroup = __d_cgrp(file->f_dentry->d_parent);
2161 file->f_op = &cgroup_seqfile_operations;
2162 err = single_open(file, cgroup_seqfile_show, state);
2163 if (err < 0)
2164 kfree(state);
2165 } else if (cft->open)
Paul Menageddbcc7e2007-10-18 23:39:30 -07002166 err = cft->open(inode, file);
2167 else
2168 err = 0;
2169
2170 return err;
2171}
2172
2173static int cgroup_file_release(struct inode *inode, struct file *file)
2174{
2175 struct cftype *cft = __d_cft(file->f_dentry);
2176 if (cft->release)
2177 return cft->release(inode, file);
2178 return 0;
2179}
2180
2181/*
2182 * cgroup_rename - Only allow simple rename of directories in place.
2183 */
2184static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry,
2185 struct inode *new_dir, struct dentry *new_dentry)
2186{
2187 if (!S_ISDIR(old_dentry->d_inode->i_mode))
2188 return -ENOTDIR;
2189 if (new_dentry->d_inode)
2190 return -EEXIST;
2191 if (old_dir != new_dir)
2192 return -EIO;
2193 return simple_rename(old_dir, old_dentry, new_dir, new_dentry);
2194}
2195
Alexey Dobriyan828c0952009-10-01 15:43:56 -07002196static const struct file_operations cgroup_file_operations = {
Paul Menageddbcc7e2007-10-18 23:39:30 -07002197 .read = cgroup_file_read,
2198 .write = cgroup_file_write,
2199 .llseek = generic_file_llseek,
2200 .open = cgroup_file_open,
2201 .release = cgroup_file_release,
2202};
2203
Alexey Dobriyan6e1d5dc2009-09-21 17:01:11 -07002204static const struct inode_operations cgroup_dir_inode_operations = {
Al Viroc72a04e2011-01-14 05:31:45 +00002205 .lookup = cgroup_lookup,
Paul Menageddbcc7e2007-10-18 23:39:30 -07002206 .mkdir = cgroup_mkdir,
2207 .rmdir = cgroup_rmdir,
2208 .rename = cgroup_rename,
2209};
2210
Al Viroc72a04e2011-01-14 05:31:45 +00002211static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
2212{
2213 if (dentry->d_name.len > NAME_MAX)
2214 return ERR_PTR(-ENAMETOOLONG);
2215 d_add(dentry, NULL);
2216 return NULL;
2217}
2218
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08002219/*
2220 * Check if a file is a control file
2221 */
2222static inline struct cftype *__file_cft(struct file *file)
2223{
2224 if (file->f_dentry->d_inode->i_fop != &cgroup_file_operations)
2225 return ERR_PTR(-EINVAL);
2226 return __d_cft(file->f_dentry);
2227}
2228
Nick Piggin5adcee12011-01-07 17:49:20 +11002229static int cgroup_create_file(struct dentry *dentry, mode_t mode,
2230 struct super_block *sb)
2231{
Paul Menageddbcc7e2007-10-18 23:39:30 -07002232 struct inode *inode;
2233
2234 if (!dentry)
2235 return -ENOENT;
2236 if (dentry->d_inode)
2237 return -EEXIST;
2238
2239 inode = cgroup_new_inode(mode, sb);
2240 if (!inode)
2241 return -ENOMEM;
2242
2243 if (S_ISDIR(mode)) {
2244 inode->i_op = &cgroup_dir_inode_operations;
2245 inode->i_fop = &simple_dir_operations;
2246
2247 /* start off with i_nlink == 2 (for "." entry) */
2248 inc_nlink(inode);
2249
2250 /* start with the directory inode held, so that we can
2251 * populate it without racing with another mkdir */
Paul Menage817929e2007-10-18 23:39:36 -07002252 mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002253 } else if (S_ISREG(mode)) {
2254 inode->i_size = 0;
2255 inode->i_fop = &cgroup_file_operations;
2256 }
Paul Menageddbcc7e2007-10-18 23:39:30 -07002257 d_instantiate(dentry, inode);
2258 dget(dentry); /* Extra count - pin the dentry in core */
2259 return 0;
2260}
2261
2262/*
Li Zefana043e3b2008-02-23 15:24:09 -08002263 * cgroup_create_dir - create a directory for an object.
2264 * @cgrp: the cgroup we create the directory for. It must have a valid
2265 * ->parent field. And we are going to fill its ->dentry field.
2266 * @dentry: dentry of the new cgroup
2267 * @mode: mode to set on new directory.
Paul Menageddbcc7e2007-10-18 23:39:30 -07002268 */
Paul Menagebd89aab2007-10-18 23:40:44 -07002269static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry,
Li Zefan099fca32009-04-02 16:57:29 -07002270 mode_t mode)
Paul Menageddbcc7e2007-10-18 23:39:30 -07002271{
2272 struct dentry *parent;
2273 int error = 0;
2274
Paul Menagebd89aab2007-10-18 23:40:44 -07002275 parent = cgrp->parent->dentry;
2276 error = cgroup_create_file(dentry, S_IFDIR | mode, cgrp->root->sb);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002277 if (!error) {
Paul Menagebd89aab2007-10-18 23:40:44 -07002278 dentry->d_fsdata = cgrp;
Paul Menageddbcc7e2007-10-18 23:39:30 -07002279 inc_nlink(parent->d_inode);
Paul Menagea47295e2009-01-07 18:07:44 -08002280 rcu_assign_pointer(cgrp->dentry, dentry);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002281 dget(dentry);
2282 }
2283 dput(dentry);
2284
2285 return error;
2286}
2287
Li Zefan099fca32009-04-02 16:57:29 -07002288/**
2289 * cgroup_file_mode - deduce file mode of a control file
2290 * @cft: the control file in question
2291 *
2292 * returns cft->mode if ->mode is not 0
2293 * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
2294 * returns S_IRUGO if it has only a read handler
2295 * returns S_IWUSR if it has only a write hander
2296 */
2297static mode_t cgroup_file_mode(const struct cftype *cft)
2298{
2299 mode_t mode = 0;
2300
2301 if (cft->mode)
2302 return cft->mode;
2303
2304 if (cft->read || cft->read_u64 || cft->read_s64 ||
2305 cft->read_map || cft->read_seq_string)
2306 mode |= S_IRUGO;
2307
2308 if (cft->write || cft->write_u64 || cft->write_s64 ||
2309 cft->write_string || cft->trigger)
2310 mode |= S_IWUSR;
2311
2312 return mode;
2313}
2314
Paul Menagebd89aab2007-10-18 23:40:44 -07002315int cgroup_add_file(struct cgroup *cgrp,
Paul Menageddbcc7e2007-10-18 23:39:30 -07002316 struct cgroup_subsys *subsys,
2317 const struct cftype *cft)
2318{
Paul Menagebd89aab2007-10-18 23:40:44 -07002319 struct dentry *dir = cgrp->dentry;
Paul Menageddbcc7e2007-10-18 23:39:30 -07002320 struct dentry *dentry;
2321 int error;
Li Zefan099fca32009-04-02 16:57:29 -07002322 mode_t mode;
Paul Menageddbcc7e2007-10-18 23:39:30 -07002323
2324 char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
Paul Menagebd89aab2007-10-18 23:40:44 -07002325 if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
Paul Menageddbcc7e2007-10-18 23:39:30 -07002326 strcpy(name, subsys->name);
2327 strcat(name, ".");
2328 }
2329 strcat(name, cft->name);
2330 BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
2331 dentry = lookup_one_len(name, dir, strlen(name));
2332 if (!IS_ERR(dentry)) {
Li Zefan099fca32009-04-02 16:57:29 -07002333 mode = cgroup_file_mode(cft);
2334 error = cgroup_create_file(dentry, mode | S_IFREG,
Paul Menagebd89aab2007-10-18 23:40:44 -07002335 cgrp->root->sb);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002336 if (!error)
2337 dentry->d_fsdata = (void *)cft;
2338 dput(dentry);
2339 } else
2340 error = PTR_ERR(dentry);
2341 return error;
2342}
Ben Blume6a11052010-03-10 15:22:09 -08002343EXPORT_SYMBOL_GPL(cgroup_add_file);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002344
Paul Menagebd89aab2007-10-18 23:40:44 -07002345int cgroup_add_files(struct cgroup *cgrp,
Paul Menageddbcc7e2007-10-18 23:39:30 -07002346 struct cgroup_subsys *subsys,
2347 const struct cftype cft[],
2348 int count)
2349{
2350 int i, err;
2351 for (i = 0; i < count; i++) {
Paul Menagebd89aab2007-10-18 23:40:44 -07002352 err = cgroup_add_file(cgrp, subsys, &cft[i]);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002353 if (err)
2354 return err;
2355 }
2356 return 0;
2357}
Ben Blume6a11052010-03-10 15:22:09 -08002358EXPORT_SYMBOL_GPL(cgroup_add_files);
Paul Menageddbcc7e2007-10-18 23:39:30 -07002359
Li Zefana043e3b2008-02-23 15:24:09 -08002360/**
2361 * cgroup_task_count - count the number of tasks in a cgroup.
2362 * @cgrp: the cgroup in question
2363 *
2364 * Return the number of tasks in the cgroup.
2365 */
Paul Menagebd89aab2007-10-18 23:40:44 -07002366int cgroup_task_count(const struct cgroup *cgrp)
Paul Menagebbcb81d2007-10-18 23:39:32 -07002367{
2368 int count = 0;
KOSAKI Motohiro71cbb942008-07-25 01:46:55 -07002369 struct cg_cgroup_link *link;
Paul Menagebbcb81d2007-10-18 23:39:32 -07002370
Paul Menage817929e2007-10-18 23:39:36 -07002371 read_lock(&css_set_lock);
KOSAKI Motohiro71cbb942008-07-25 01:46:55 -07002372 list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) {
Lai Jiangshan146aa1b2008-10-18 20:28:03 -07002373 count += atomic_read(&link->cg->refcount);
Paul Menage817929e2007-10-18 23:39:36 -07002374 }
2375 read_unlock(&css_set_lock);
Paul Menagebbcb81d2007-10-18 23:39:32 -07002376 return count;
2377}
2378
2379/*
Paul Menage817929e2007-10-18 23:39:36 -07002380 * Advance a list_head iterator. The iterator should be positioned at
2381 * the start of a css_set
2382 */
Paul Menagebd89aab2007-10-18 23:40:44 -07002383static void cgroup_advance_iter(struct cgroup *cgrp,
Paul Menage7717f7b2009-09-23 15:56:22 -07002384 struct cgroup_iter *it)
Paul Menage817929e2007-10-18 23:39:36 -07002385{
2386 struct list_head *l = it->cg_link;
2387 struct cg_cgroup_link *link;
2388 struct css_set *cg;
2389
2390 /* Advance to the next non-empty css_set */
2391 do {
2392 l = l->next;
Paul Menagebd89aab2007-10-18 23:40:44 -07002393 if (l == &cgrp->css_sets) {
Paul Menage817929e2007-10-18 23:39:36 -07002394 it->cg_link = NULL;
2395 return;
2396 }
Paul Menagebd89aab2007-10-18 23:40:44 -07002397 link = list_entry(l, struct cg_cgroup_link, cgrp_link_list);
Paul Menage817929e2007-10-18 23:39:36 -07002398 cg = link->cg;
2399 } while (list_empty(&cg->tasks));
2400 it->cg_link = l;
2401 it->task = cg->tasks.next;
2402}
2403
Cliff Wickman31a7df02008-02-07 00:14:42 -08002404/*
2405 * To reduce the fork() overhead for systems that are not actually
2406 * using their cgroups capability, we don't maintain the lists running
2407 * through each css_set to its tasks until we see the list actually
2408 * used - in other words after the first call to cgroup_iter_start().
2409 *
2410 * The tasklist_lock is not held here, as do_each_thread() and
2411 * while_each_thread() are protected by RCU.
2412 */
Adrian Bunk3df91fe2008-04-29 00:59:54 -07002413static void cgroup_enable_task_cg_lists(void)
Cliff Wickman31a7df02008-02-07 00:14:42 -08002414{
2415 struct task_struct *p, *g;
2416 write_lock(&css_set_lock);
2417 use_task_css_set_links = 1;
2418 do_each_thread(g, p) {
2419 task_lock(p);
Li Zefan0e043882008-04-17 11:37:15 +08002420 /*
2421 * We should check if the process is exiting, otherwise
2422 * it will race with cgroup_exit() in that the list
2423 * entry won't be deleted though the process has exited.
2424 */
2425 if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list))
Cliff Wickman31a7df02008-02-07 00:14:42 -08002426 list_add(&p->cg_list, &p->cgroups->tasks);
2427 task_unlock(p);
2428 } while_each_thread(g, p);
2429 write_unlock(&css_set_lock);
2430}
2431
Paul Menagebd89aab2007-10-18 23:40:44 -07002432void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it)
Paul Menage817929e2007-10-18 23:39:36 -07002433{
2434 /*
2435 * The first time anyone tries to iterate across a cgroup,
2436 * we need to enable the list linking each css_set to its
2437 * tasks, and fix up all existing tasks.
2438 */
Cliff Wickman31a7df02008-02-07 00:14:42 -08002439 if (!use_task_css_set_links)
2440 cgroup_enable_task_cg_lists();
2441
Paul Menage817929e2007-10-18 23:39:36 -07002442 read_lock(&css_set_lock);
Paul Menagebd89aab2007-10-18 23:40:44 -07002443 it->cg_link = &cgrp->css_sets;
2444 cgroup_advance_iter(cgrp, it);
Paul Menage817929e2007-10-18 23:39:36 -07002445}
2446
Paul Menagebd89aab2007-10-18 23:40:44 -07002447struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
Paul Menage817929e2007-10-18 23:39:36 -07002448 struct cgroup_iter *it)
2449{
2450 struct task_struct *res;
2451 struct list_head *l = it->task;
Lai Jiangshan2019f632009-01-07 18:07:36 -08002452 struct cg_cgroup_link *link;
Paul Menage817929e2007-10-18 23:39:36 -07002453
2454 /* If the iterator cg is NULL, we have no tasks */
2455 if (!it->cg_link)
2456 return NULL;
2457 res = list_entry(l, struct task_struct, cg_list);
2458 /* Advance iterator to find next entry */
2459 l = l->next;
Lai Jiangshan2019f632009-01-07 18:07:36 -08002460 link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list);
2461 if (l == &link->cg->tasks) {
Paul Menage817929e2007-10-18 23:39:36 -07002462 /* We reached the end of this task list - move on to
2463 * the next cg_cgroup_link */
Paul Menagebd89aab2007-10-18 23:40:44 -07002464 cgroup_advance_iter(cgrp, it);
Paul Menage817929e2007-10-18 23:39:36 -07002465 } else {
2466 it->task = l;
2467 }
2468 return res;
2469}
2470
Paul Menagebd89aab2007-10-18 23:40:44 -07002471void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it)
Paul Menage817929e2007-10-18 23:39:36 -07002472{
2473 read_unlock(&css_set_lock);
2474}
2475
Cliff Wickman31a7df02008-02-07 00:14:42 -08002476static inline int started_after_time(struct task_struct *t1,
2477 struct timespec *time,
2478 struct task_struct *t2)
2479{
2480 int start_diff = timespec_compare(&t1->start_time, time);
2481 if (start_diff > 0) {
2482 return 1;
2483 } else if (start_diff < 0) {
2484 return 0;
2485 } else {
2486 /*
2487 * Arbitrarily, if two processes started at the same
2488 * time, we'll say that the lower pointer value
2489 * started first. Note that t2 may have exited by now
2490 * so this may not be a valid pointer any longer, but
2491 * that's fine - it still serves to distinguish
2492 * between two tasks started (effectively) simultaneously.
2493 */
2494 return t1 > t2;
2495 }
2496}
2497
2498/*
2499 * This function is a callback from heap_insert() and is used to order
2500 * the heap.
2501 * In this case we order the heap in descending task start time.
2502 */
2503static inline int started_after(void *p1, void *p2)
2504{
2505 struct task_struct *t1 = p1;
2506 struct task_struct *t2 = p2;
2507 return started_after_time(t1, &t2->start_time, t2);
2508}
2509
2510/**
2511 * cgroup_scan_tasks - iterate though all the tasks in a cgroup
2512 * @scan: struct cgroup_scanner containing arguments for the scan
2513 *
2514 * Arguments include pointers to callback functions test_task() and
2515 * process_task().
2516 * Iterate through all the tasks in a cgroup, calling test_task() for each,
2517 * and if it returns true, call process_task() for it also.
2518 * The test_task pointer may be NULL, meaning always true (select all tasks).
2519 * Effectively duplicates cgroup_iter_{start,next,end}()
2520 * but does not lock css_set_lock for the call to process_task().
2521 * The struct cgroup_scanner may be embedded in any structure of the caller's
2522 * creation.
2523 * It is guaranteed that process_task() will act on every task that
2524 * is a member of the cgroup for the duration of this call. This
2525 * function may or may not call process_task() for tasks that exit
2526 * or move to a different cgroup during the call, or are forked or
2527 * move into the cgroup during the call.
2528 *
2529 * Note that test_task() may be called with locks held, and may in some
2530 * situations be called multiple times for the same task, so it should
2531 * be cheap.
2532 * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been
2533 * pre-allocated and will be used for heap operations (and its "gt" member will
2534 * be overwritten), else a temporary heap will be used (allocation of which
2535 * may cause this function to fail).
2536 */
2537int cgroup_scan_tasks(struct cgroup_scanner *scan)
2538{
2539 int retval, i;
2540 struct cgroup_iter it;
2541 struct task_struct *p, *dropped;
2542 /* Never dereference latest_task, since it's not refcounted */
2543 struct task_struct *latest_task = NULL;
2544 struct ptr_heap tmp_heap;
2545 struct ptr_heap *heap;
2546 struct timespec latest_time = { 0, 0 };
2547
2548 if (scan->heap) {
2549 /* The caller supplied our heap and pre-allocated its memory */
2550 heap = scan->heap;
2551 heap->gt = &started_after;
2552 } else {
2553 /* We need to allocate our own heap memory */
2554 heap = &tmp_heap;
2555 retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after);
2556 if (retval)
2557 /* cannot allocate the heap */
2558 return retval;
2559 }
2560
2561 again:
2562 /*
2563 * Scan tasks in the cgroup, using the scanner's "test_task" callback
2564 * to determine which are of interest, and using the scanner's
2565 * "process_task" callback to process any of them that need an update.
2566 * Since we don't want to hold any locks during the task updates,
2567 * gather tasks to be processed in a heap structure.
2568 * The heap is sorted by descending task start time.
2569 * If the statically-sized heap fills up, we overflow tasks that
2570 * started later, and in future iterations only consider tasks that
2571 * started after the latest task in the previous pass. This
2572 * guarantees forward progress and that we don't miss any tasks.
2573 */
2574 heap->size = 0;
2575 cgroup_iter_start(scan->cg, &it);
2576 while ((p = cgroup_iter_next(scan->cg, &it))) {
2577 /*
2578 * Only affect tasks that qualify per the caller's callback,
2579 * if he provided one
2580 */
2581 if (scan->test_task && !scan->test_task(p, scan))
2582 continue;
2583 /*
2584 * Only process tasks that started after the last task
2585 * we processed
2586 */
2587 if (!started_after_time(p, &latest_time, latest_task))
2588 continue;
2589 dropped = heap_insert(heap, p);
2590 if (dropped == NULL) {
2591 /*
2592 * The new task was inserted; the heap wasn't
2593 * previously full
2594 */
2595 get_task_struct(p);
2596 } else if (dropped != p) {
2597 /*
2598 * The new task was inserted, and pushed out a
2599 * different task
2600 */
2601 get_task_struct(p);
2602 put_task_struct(dropped);
2603 }
2604 /*
2605 * Else the new task was newer than anything already in
2606 * the heap and wasn't inserted
2607 */
2608 }
2609 cgroup_iter_end(scan->cg, &it);
2610
2611 if (heap->size) {
2612 for (i = 0; i < heap->size; i++) {
Paul Jackson4fe91d52008-04-29 00:59:55 -07002613 struct task_struct *q = heap->ptrs[i];
Cliff Wickman31a7df02008-02-07 00:14:42 -08002614 if (i == 0) {
Paul Jackson4fe91d52008-04-29 00:59:55 -07002615 latest_time = q->start_time;
2616 latest_task = q;
Cliff Wickman31a7df02008-02-07 00:14:42 -08002617 }
2618 /* Process the task per the caller's callback */
Paul Jackson4fe91d52008-04-29 00:59:55 -07002619 scan->process_task(q, scan);
2620 put_task_struct(q);
Cliff Wickman31a7df02008-02-07 00:14:42 -08002621 }
2622 /*
2623 * If we had to process any tasks at all, scan again
2624 * in case some of them were in the middle of forking
2625 * children that didn't get processed.
2626 * Not the most efficient way to do it, but it avoids
2627 * having to take callback_mutex in the fork path
2628 */
2629 goto again;
2630 }
2631 if (heap == &tmp_heap)
2632 heap_free(&tmp_heap);
2633 return 0;
2634}
2635
Paul Menage817929e2007-10-18 23:39:36 -07002636/*
Ben Blum102a7752009-09-23 15:56:26 -07002637 * Stuff for reading the 'tasks'/'procs' files.
Paul Menagebbcb81d2007-10-18 23:39:32 -07002638 *
2639 * Reading this file can return large amounts of data if a cgroup has
2640 * *lots* of attached tasks. So it may need several calls to read(),
2641 * but we cannot guarantee that the information we produce is correct
2642 * unless we produce it entirely atomically.
2643 *
Paul Menagebbcb81d2007-10-18 23:39:32 -07002644 */
Paul Menagebbcb81d2007-10-18 23:39:32 -07002645
2646/*
Ben Blumd1d9fd32009-09-23 15:56:28 -07002647 * The following two functions "fix" the issue where there are more pids
2648 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
2649 * TODO: replace with a kernel-wide solution to this problem
2650 */
2651#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
2652static void *pidlist_allocate(int count)
2653{
2654 if (PIDLIST_TOO_LARGE(count))
2655 return vmalloc(count * sizeof(pid_t));
2656 else
2657 return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
2658}
2659static void pidlist_free(void *p)
2660{
2661 if (is_vmalloc_addr(p))
2662 vfree(p);
2663 else
2664 kfree(p);
2665}
2666static void *pidlist_resize(void *p, int newcount)
2667{
2668 void *newlist;
2669 /* note: if new alloc fails, old p will still be valid either way */
2670 if (is_vmalloc_addr(p)) {
2671 newlist = vmalloc(newcount * sizeof(pid_t));
2672 if (!newlist)
2673 return NULL;
2674 memcpy(newlist, p, newcount * sizeof(pid_t));
2675 vfree(p);
2676 } else {
2677 newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL);
2678 }
2679 return newlist;
2680}
2681
2682/*
Ben Blum102a7752009-09-23 15:56:26 -07002683 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
2684 * If the new stripped list is sufficiently smaller and there's enough memory
2685 * to allocate a new buffer, will let go of the unneeded memory. Returns the
2686 * number of unique elements.
Paul Menagebbcb81d2007-10-18 23:39:32 -07002687 */
Ben Blum102a7752009-09-23 15:56:26 -07002688/* is the size difference enough that we should re-allocate the array? */
2689#define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new))
2690static int pidlist_uniq(pid_t **p, int length)
Paul Menagebbcb81d2007-10-18 23:39:32 -07002691{
Ben Blum102a7752009-09-23 15:56:26 -07002692 int src, dest = 1;
2693 pid_t *list = *p;
2694 pid_t *newlist;
2695
2696 /*
2697 * we presume the 0th element is unique, so i starts at 1. trivial
2698 * edge cases first; no work needs to be done for either
2699 */
2700 if (length == 0 || length == 1)
2701 return length;
2702 /* src and dest walk down the list; dest counts unique elements */
2703 for (src = 1; src < length; src++) {
2704 /* find next unique element */
2705 while (list[src] == list[src-1]) {
2706 src++;
2707 if (src == length)
2708 goto after;
2709 }
2710 /* dest always points to where the next unique element goes */
2711 list[dest] = list[src];
2712 dest++;
2713 }
2714after:
2715 /*
2716 * if the length difference is large enough, we want to allocate a
2717 * smaller buffer to save memory. if this fails due to out of memory,
2718 * we'll just stay with what we've got.
2719 */
2720 if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) {
Ben Blumd1d9fd32009-09-23 15:56:28 -07002721 newlist = pidlist_resize(list, dest);
Ben Blum102a7752009-09-23 15:56:26 -07002722 if (newlist)
2723 *p = newlist;
2724 }
2725 return dest;
2726}
2727
2728static int cmppid(const void *a, const void *b)
2729{
2730 return *(pid_t *)a - *(pid_t *)b;
2731}
2732
2733/*
Ben Blum72a8cb32009-09-23 15:56:27 -07002734 * find the appropriate pidlist for our purpose (given procs vs tasks)
2735 * returns with the lock on that pidlist already held, and takes care
2736 * of the use count, or returns NULL with no locks held if we're out of
2737 * memory.
2738 */
2739static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
2740 enum cgroup_filetype type)
2741{
2742 struct cgroup_pidlist *l;
2743 /* don't need task_nsproxy() if we're looking at ourself */
Li Zefanb70cc5f2010-03-10 15:22:12 -08002744 struct pid_namespace *ns = current->nsproxy->pid_ns;
2745
Ben Blum72a8cb32009-09-23 15:56:27 -07002746 /*
2747 * We can't drop the pidlist_mutex before taking the l->mutex in case
2748 * the last ref-holder is trying to remove l from the list at the same
2749 * time. Holding the pidlist_mutex precludes somebody taking whichever
2750 * list we find out from under us - compare release_pid_array().
2751 */
2752 mutex_lock(&cgrp->pidlist_mutex);
2753 list_for_each_entry(l, &cgrp->pidlists, links) {
2754 if (l->key.type == type && l->key.ns == ns) {
Ben Blum72a8cb32009-09-23 15:56:27 -07002755 /* make sure l doesn't vanish out from under us */
2756 down_write(&l->mutex);
2757 mutex_unlock(&cgrp->pidlist_mutex);
Ben Blum72a8cb32009-09-23 15:56:27 -07002758 return l;
2759 }
2760 }
2761 /* entry not found; create a new one */
2762 l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
2763 if (!l) {
2764 mutex_unlock(&cgrp->pidlist_mutex);
Ben Blum72a8cb32009-09-23 15:56:27 -07002765 return l;
2766 }
2767 init_rwsem(&l->mutex);
2768 down_write(&l->mutex);
2769 l->key.type = type;
Li Zefanb70cc5f2010-03-10 15:22:12 -08002770 l->key.ns = get_pid_ns(ns);
Ben Blum72a8cb32009-09-23 15:56:27 -07002771 l->use_count = 0; /* don't increment here */
2772 l->list = NULL;
2773 l->owner = cgrp;
2774 list_add(&l->links, &cgrp->pidlists);
2775 mutex_unlock(&cgrp->pidlist_mutex);
2776 return l;
2777}
2778
2779/*
Ben Blum102a7752009-09-23 15:56:26 -07002780 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
2781 */
Ben Blum72a8cb32009-09-23 15:56:27 -07002782static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
2783 struct cgroup_pidlist **lp)
Ben Blum102a7752009-09-23 15:56:26 -07002784{
2785 pid_t *array;
2786 int length;
2787 int pid, n = 0; /* used for populating the array */
Paul Menage817929e2007-10-18 23:39:36 -07002788 struct cgroup_iter it;
2789 struct task_struct *tsk;
Ben Blum102a7752009-09-23 15:56:26 -07002790 struct cgroup_pidlist *l;
2791
2792 /*
2793 * If cgroup gets more users after we read count, we won't have
2794 * enough space - tough. This race is indistinguishable to the
2795 * caller from the case that the additional cgroup users didn't
2796 * show up until sometime later on.
2797 */
2798 length = cgroup_task_count(cgrp);
Ben Blumd1d9fd32009-09-23 15:56:28 -07002799 array = pidlist_allocate(length);
Ben Blum102a7752009-09-23 15:56:26 -07002800 if (!array)
2801 return -ENOMEM;
2802 /* now, populate the array */
Paul Menagebd89aab2007-10-18 23:40:44 -07002803 cgroup_iter_start(cgrp, &it);
2804 while ((tsk = cgroup_iter_next(cgrp, &it))) {
Ben Blum102a7752009-09-23 15:56:26 -07002805 if (unlikely(n == length))
Paul Menage817929e2007-10-18 23:39:36 -07002806 break;
Ben Blum102a7752009-09-23 15:56:26 -07002807 /* get tgid or pid for procs or tasks file respectively */
Ben Blum72a8cb32009-09-23 15:56:27 -07002808 if (type == CGROUP_FILE_PROCS)
2809 pid = task_tgid_vnr(tsk);
2810 else
2811 pid = task_pid_vnr(tsk);
Ben Blum102a7752009-09-23 15:56:26 -07002812 if (pid > 0) /* make sure to only use valid results */
2813 array[n++] = pid;
Paul Menage817929e2007-10-18 23:39:36 -07002814 }
Paul Menagebd89aab2007-10-18 23:40:44 -07002815 cgroup_iter_end(cgrp, &it);
Ben Blum102a7752009-09-23 15:56:26 -07002816 length = n;
2817 /* now sort & (if procs) strip out duplicates */
2818 sort(array, length, sizeof(pid_t), cmppid, NULL);
Ben Blum72a8cb32009-09-23 15:56:27 -07002819 if (type == CGROUP_FILE_PROCS)
Ben Blum102a7752009-09-23 15:56:26 -07002820 length = pidlist_uniq(&array, length);
Ben Blum72a8cb32009-09-23 15:56:27 -07002821 l = cgroup_pidlist_find(cgrp, type);
2822 if (!l) {
Ben Blumd1d9fd32009-09-23 15:56:28 -07002823 pidlist_free(array);
Ben Blum72a8cb32009-09-23 15:56:27 -07002824 return -ENOMEM;
Ben Blum102a7752009-09-23 15:56:26 -07002825 }
Ben Blum72a8cb32009-09-23 15:56:27 -07002826 /* store array, freeing old if necessary - lock already held */
Ben Blumd1d9fd32009-09-23 15:56:28 -07002827 pidlist_free(l->list);
Ben Blum102a7752009-09-23 15:56:26 -07002828 l->list = array;
2829 l->length = length;
2830 l->use_count++;
2831 up_write(&l->mutex);
Ben Blum72a8cb32009-09-23 15:56:27 -07002832 *lp = l;
Ben Blum102a7752009-09-23 15:56:26 -07002833 return 0;
Paul Menagebbcb81d2007-10-18 23:39:32 -07002834}
2835
Balbir Singh846c7bb2007-10-18 23:39:44 -07002836/**
Li Zefana043e3b2008-02-23 15:24:09 -08002837 * cgroupstats_build - build and fill cgroupstats
Balbir Singh846c7bb2007-10-18 23:39:44 -07002838 * @stats: cgroupstats to fill information into
2839 * @dentry: A dentry entry belonging to the cgroup for which stats have
2840 * been requested.
Li Zefana043e3b2008-02-23 15:24:09 -08002841 *
2842 * Build and fill cgroupstats so that taskstats can export it to user
2843 * space.
Balbir Singh846c7bb2007-10-18 23:39:44 -07002844 */
2845int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
2846{
2847 int ret = -EINVAL;
Paul Menagebd89aab2007-10-18 23:40:44 -07002848 struct cgroup *cgrp;
Balbir Singh846c7bb2007-10-18 23:39:44 -07002849 struct cgroup_iter it;
2850 struct task_struct *tsk;
Li Zefan33d283b2008-11-19 15:36:48 -08002851
Balbir Singh846c7bb2007-10-18 23:39:44 -07002852 /*
Li Zefan33d283b2008-11-19 15:36:48 -08002853 * Validate dentry by checking the superblock operations,
2854 * and make sure it's a directory.
Balbir Singh846c7bb2007-10-18 23:39:44 -07002855 */
Li Zefan33d283b2008-11-19 15:36:48 -08002856 if (dentry->d_sb->s_op != &cgroup_ops ||
2857 !S_ISDIR(dentry->d_inode->i_mode))
Balbir Singh846c7bb2007-10-18 23:39:44 -07002858 goto err;
2859
2860 ret = 0;
Paul Menagebd89aab2007-10-18 23:40:44 -07002861 cgrp = dentry->d_fsdata;
Balbir Singh846c7bb2007-10-18 23:39:44 -07002862
Paul Menagebd89aab2007-10-18 23:40:44 -07002863 cgroup_iter_start(cgrp, &it);
2864 while ((tsk = cgroup_iter_next(cgrp, &it))) {
Balbir Singh846c7bb2007-10-18 23:39:44 -07002865 switch (tsk->state) {
2866 case TASK_RUNNING:
2867 stats->nr_running++;
2868 break;
2869 case TASK_INTERRUPTIBLE:
2870 stats->nr_sleeping++;
2871 break;
2872 case TASK_UNINTERRUPTIBLE:
2873 stats->nr_uninterruptible++;
2874 break;
2875 case TASK_STOPPED:
2876 stats->nr_stopped++;
2877 break;
2878 default:
2879 if (delayacct_is_task_waiting_on_io(tsk))
2880 stats->nr_io_wait++;
2881 break;
2882 }
2883 }
Paul Menagebd89aab2007-10-18 23:40:44 -07002884 cgroup_iter_end(cgrp, &it);
Balbir Singh846c7bb2007-10-18 23:39:44 -07002885
Balbir Singh846c7bb2007-10-18 23:39:44 -07002886err:
2887 return ret;
2888}
2889
Paul Menage8f3ff202009-09-23 15:56:25 -07002890
Paul Menagecc31edc2008-10-18 20:28:04 -07002891/*
Ben Blum102a7752009-09-23 15:56:26 -07002892 * seq_file methods for the tasks/procs files. The seq_file position is the
Paul Menagecc31edc2008-10-18 20:28:04 -07002893 * next pid to display; the seq_file iterator is a pointer to the pid
Ben Blum102a7752009-09-23 15:56:26 -07002894 * in the cgroup->l->list array.
Paul Menagecc31edc2008-10-18 20:28:04 -07002895 */
2896
Ben Blum102a7752009-09-23 15:56:26 -07002897static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
Paul Menagecc31edc2008-10-18 20:28:04 -07002898{
2899 /*
2900 * Initially we receive a position value that corresponds to
2901 * one more than the last pid shown (or 0 on the first call or
2902 * after a seek to the start). Use a binary-search to find the
2903 * next pid to display, if any
2904 */
Ben Blum102a7752009-09-23 15:56:26 -07002905 struct cgroup_pidlist *l = s->private;
Paul Menagecc31edc2008-10-18 20:28:04 -07002906 int index = 0, pid = *pos;
2907 int *iter;
2908
Ben Blum102a7752009-09-23 15:56:26 -07002909 down_read(&l->mutex);
Paul Menagecc31edc2008-10-18 20:28:04 -07002910 if (pid) {
Ben Blum102a7752009-09-23 15:56:26 -07002911 int end = l->length;
Stephen Rothwell20777762008-10-21 16:11:20 +11002912
Paul Menagecc31edc2008-10-18 20:28:04 -07002913 while (index < end) {
2914 int mid = (index + end) / 2;
Ben Blum102a7752009-09-23 15:56:26 -07002915 if (l->list[mid] == pid) {
Paul Menagecc31edc2008-10-18 20:28:04 -07002916 index = mid;
2917 break;
Ben Blum102a7752009-09-23 15:56:26 -07002918 } else if (l->list[mid] <= pid)
Paul Menagecc31edc2008-10-18 20:28:04 -07002919 index = mid + 1;
2920 else
2921 end = mid;
2922 }
2923 }
2924 /* If we're off the end of the array, we're done */
Ben Blum102a7752009-09-23 15:56:26 -07002925 if (index >= l->length)
Paul Menagecc31edc2008-10-18 20:28:04 -07002926 return NULL;
2927 /* Update the abstract position to be the actual pid that we found */
Ben Blum102a7752009-09-23 15:56:26 -07002928 iter = l->list + index;
Paul Menagecc31edc2008-10-18 20:28:04 -07002929 *pos = *iter;
2930 return iter;
Paul Menagebbcb81d2007-10-18 23:39:32 -07002931}
2932
Ben Blum102a7752009-09-23 15:56:26 -07002933static void cgroup_pidlist_stop(struct seq_file *s, void *v)
Paul Menagecc31edc2008-10-18 20:28:04 -07002934{
Ben Blum102a7752009-09-23 15:56:26 -07002935 struct cgroup_pidlist *l = s->private;
2936 up_read(&l->mutex);
Paul Menagecc31edc2008-10-18 20:28:04 -07002937}
2938
Ben Blum102a7752009-09-23 15:56:26 -07002939static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
Paul Menagecc31edc2008-10-18 20:28:04 -07002940{
Ben Blum102a7752009-09-23 15:56:26 -07002941 struct cgroup_pidlist *l = s->private;
2942 pid_t *p = v;
2943 pid_t *end = l->list + l->length;
Paul Menagecc31edc2008-10-18 20:28:04 -07002944 /*
2945 * Advance to the next pid in the array. If this goes off the
2946 * end, we're done
2947 */
2948 p++;
2949 if (p >= end) {
2950 return NULL;
2951 } else {
2952 *pos = *p;
2953 return p;
2954 }
2955}
2956
Ben Blum102a7752009-09-23 15:56:26 -07002957static int cgroup_pidlist_show(struct seq_file *s, void *v)
Paul Menagecc31edc2008-10-18 20:28:04 -07002958{
2959 return seq_printf(s, "%d\n", *(int *)v);
2960}
2961
Ben Blum102a7752009-09-23 15:56:26 -07002962/*
2963 * seq_operations functions for iterating on pidlists through seq_file -
2964 * independent of whether it's tasks or procs
2965 */
2966static const struct seq_operations cgroup_pidlist_seq_operations = {
2967 .start = cgroup_pidlist_start,
2968 .stop = cgroup_pidlist_stop,
2969 .next = cgroup_pidlist_next,
2970 .show = cgroup_pidlist_show,
Paul Menagecc31edc2008-10-18 20:28:04 -07002971};
2972
Ben Blum102a7752009-09-23 15:56:26 -07002973static void cgroup_release_pid_array(struct cgroup_pidlist *l)
Paul Menagecc31edc2008-10-18 20:28:04 -07002974{
Ben Blum72a8cb32009-09-23 15:56:27 -07002975 /*
2976 * the case where we're the last user of this particular pidlist will
2977 * have us remove it from the cgroup's list, which entails taking the
2978 * mutex. since in pidlist_find the pidlist->lock depends on cgroup->
2979 * pidlist_mutex, we have to take pidlist_mutex first.
2980 */
2981 mutex_lock(&l->owner->pidlist_mutex);
Ben Blum102a7752009-09-23 15:56:26 -07002982 down_write(&l->mutex);
2983 BUG_ON(!l->use_count);
2984 if (!--l->use_count) {
Ben Blum72a8cb32009-09-23 15:56:27 -07002985 /* we're the last user if refcount is 0; remove and free */
2986 list_del(&l->links);
2987 mutex_unlock(&l->owner->pidlist_mutex);
Ben Blumd1d9fd32009-09-23 15:56:28 -07002988 pidlist_free(l->list);
Ben Blum72a8cb32009-09-23 15:56:27 -07002989 put_pid_ns(l->key.ns);
2990 up_write(&l->mutex);
2991 kfree(l);
2992 return;
Paul Menagecc31edc2008-10-18 20:28:04 -07002993 }
Ben Blum72a8cb32009-09-23 15:56:27 -07002994 mutex_unlock(&l->owner->pidlist_mutex);
Ben Blum102a7752009-09-23 15:56:26 -07002995 up_write(&l->mutex);
Paul Menagecc31edc2008-10-18 20:28:04 -07002996}
2997
Ben Blum102a7752009-09-23 15:56:26 -07002998static int cgroup_pidlist_release(struct inode *inode, struct file *file)
Paul Menagebbcb81d2007-10-18 23:39:32 -07002999{
Ben Blum102a7752009-09-23 15:56:26 -07003000 struct cgroup_pidlist *l;
Paul Menagebbcb81d2007-10-18 23:39:32 -07003001 if (!(file->f_mode & FMODE_READ))
3002 return 0;
Ben Blum102a7752009-09-23 15:56:26 -07003003 /*
3004 * the seq_file will only be initialized if the file was opened for
3005 * reading; hence we check if it's not null only in that case.
3006 */
3007 l = ((struct seq_file *)file->private_data)->private;
3008 cgroup_release_pid_array(l);
Paul Menagecc31edc2008-10-18 20:28:04 -07003009 return seq_release(inode, file);
3010}
3011
Ben Blum102a7752009-09-23 15:56:26 -07003012static const struct file_operations cgroup_pidlist_operations = {
Paul Menagecc31edc2008-10-18 20:28:04 -07003013 .read = seq_read,
3014 .llseek = seq_lseek,
3015 .write = cgroup_file_write,
Ben Blum102a7752009-09-23 15:56:26 -07003016 .release = cgroup_pidlist_release,
Paul Menagecc31edc2008-10-18 20:28:04 -07003017};
3018
3019/*
Ben Blum102a7752009-09-23 15:56:26 -07003020 * The following functions handle opens on a file that displays a pidlist
3021 * (tasks or procs). Prepare an array of the process/thread IDs of whoever's
3022 * in the cgroup.
Paul Menagecc31edc2008-10-18 20:28:04 -07003023 */
Ben Blum102a7752009-09-23 15:56:26 -07003024/* helper function for the two below it */
Ben Blum72a8cb32009-09-23 15:56:27 -07003025static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type)
Paul Menagecc31edc2008-10-18 20:28:04 -07003026{
3027 struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
Ben Blum72a8cb32009-09-23 15:56:27 -07003028 struct cgroup_pidlist *l;
Paul Menagecc31edc2008-10-18 20:28:04 -07003029 int retval;
3030
3031 /* Nothing to do for write-only files */
3032 if (!(file->f_mode & FMODE_READ))
3033 return 0;
Paul Menagebbcb81d2007-10-18 23:39:32 -07003034
Ben Blum102a7752009-09-23 15:56:26 -07003035 /* have the array populated */
Ben Blum72a8cb32009-09-23 15:56:27 -07003036 retval = pidlist_array_load(cgrp, type, &l);
Ben Blum102a7752009-09-23 15:56:26 -07003037 if (retval)
3038 return retval;
3039 /* configure file information */
3040 file->f_op = &cgroup_pidlist_operations;
Paul Menagebbcb81d2007-10-18 23:39:32 -07003041
Ben Blum102a7752009-09-23 15:56:26 -07003042 retval = seq_open(file, &cgroup_pidlist_seq_operations);
Paul Menagecc31edc2008-10-18 20:28:04 -07003043 if (retval) {
Ben Blum102a7752009-09-23 15:56:26 -07003044 cgroup_release_pid_array(l);
Paul Menagecc31edc2008-10-18 20:28:04 -07003045 return retval;
Paul Menagebbcb81d2007-10-18 23:39:32 -07003046 }
Ben Blum102a7752009-09-23 15:56:26 -07003047 ((struct seq_file *)file->private_data)->private = l;
Paul Menagebbcb81d2007-10-18 23:39:32 -07003048 return 0;
3049}
Ben Blum102a7752009-09-23 15:56:26 -07003050static int cgroup_tasks_open(struct inode *unused, struct file *file)
3051{
Ben Blum72a8cb32009-09-23 15:56:27 -07003052 return cgroup_pidlist_open(file, CGROUP_FILE_TASKS);
Ben Blum102a7752009-09-23 15:56:26 -07003053}
3054static int cgroup_procs_open(struct inode *unused, struct file *file)
3055{
Ben Blum72a8cb32009-09-23 15:56:27 -07003056 return cgroup_pidlist_open(file, CGROUP_FILE_PROCS);
Ben Blum102a7752009-09-23 15:56:26 -07003057}
Paul Menagebbcb81d2007-10-18 23:39:32 -07003058
Paul Menagebd89aab2007-10-18 23:40:44 -07003059static u64 cgroup_read_notify_on_release(struct cgroup *cgrp,
Paul Menage81a6a5c2007-10-18 23:39:38 -07003060 struct cftype *cft)
3061{
Paul Menagebd89aab2007-10-18 23:40:44 -07003062 return notify_on_release(cgrp);
Paul Menage81a6a5c2007-10-18 23:39:38 -07003063}
3064
Paul Menage6379c102008-07-25 01:47:01 -07003065static int cgroup_write_notify_on_release(struct cgroup *cgrp,
3066 struct cftype *cft,
3067 u64 val)
3068{
3069 clear_bit(CGRP_RELEASABLE, &cgrp->flags);
3070 if (val)
3071 set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
3072 else
3073 clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
3074 return 0;
3075}
3076
Paul Menagebbcb81d2007-10-18 23:39:32 -07003077/*
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08003078 * Unregister event and free resources.
3079 *
3080 * Gets called from workqueue.
3081 */
3082static void cgroup_event_remove(struct work_struct *work)
3083{
3084 struct cgroup_event *event = container_of(work, struct cgroup_event,
3085 remove);
3086 struct cgroup *cgrp = event->cgrp;
3087
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08003088 event->cft->unregister_event(cgrp, event->cft, event->eventfd);
3089
3090 eventfd_ctx_put(event->eventfd);
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08003091 kfree(event);
Kirill A. Shutemova0a4db52010-03-10 15:22:34 -08003092 dput(cgrp->dentry);
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08003093}
3094
3095/*
3096 * Gets called on POLLHUP on eventfd when user closes it.
3097 *
3098 * Called with wqh->lock held and interrupts disabled.
3099 */
3100static int cgroup_event_wake(wait_queue_t *wait, unsigned mode,
3101 int sync, void *key)
3102{
3103 struct cgroup_event *event = container_of(wait,
3104 struct cgroup_event, wait);
3105 struct cgroup *cgrp = event->cgrp;
3106 unsigned long flags = (unsigned long)key;
3107
3108 if (flags & POLLHUP) {
Changli Gaoa93d2f12010-05-07 14:33:26 +08003109 __remove_wait_queue(event->wqh, &event->wait);
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08003110 spin_lock(&cgrp->event_list_lock);
3111 list_del(&event->list);
3112 spin_unlock(&cgrp->event_list_lock);
3113 /*
3114 * We are in atomic context, but cgroup_event_remove() may
3115 * sleep, so we have to call it in workqueue.
3116 */
3117 schedule_work(&event->remove);
3118 }
3119
3120 return 0;
3121}
3122
3123static void cgroup_event_ptable_queue_proc(struct file *file,
3124 wait_queue_head_t *wqh, poll_table *pt)
3125{
3126 struct cgroup_event *event = container_of(pt,
3127 struct cgroup_event, pt);
3128
3129 event->wqh = wqh;
3130 add_wait_queue(wqh, &event->wait);
3131}
3132
3133/*
3134 * Parse input and register new cgroup event handler.
3135 *
3136 * Input must be in format '<event_fd> <control_fd> <args>'.
3137 * Interpretation of args is defined by control file implementation.
3138 */
3139static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,
3140 const char *buffer)
3141{
3142 struct cgroup_event *event = NULL;
3143 unsigned int efd, cfd;
3144 struct file *efile = NULL;
3145 struct file *cfile = NULL;
3146 char *endp;
3147 int ret;
3148
3149 efd = simple_strtoul(buffer, &endp, 10);
3150 if (*endp != ' ')
3151 return -EINVAL;
3152 buffer = endp + 1;
3153
3154 cfd = simple_strtoul(buffer, &endp, 10);
3155 if ((*endp != ' ') && (*endp != '\0'))
3156 return -EINVAL;
3157 buffer = endp + 1;
3158
3159 event = kzalloc(sizeof(*event), GFP_KERNEL);
3160 if (!event)
3161 return -ENOMEM;
3162 event->cgrp = cgrp;
3163 INIT_LIST_HEAD(&event->list);
3164 init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc);
3165 init_waitqueue_func_entry(&event->wait, cgroup_event_wake);
3166 INIT_WORK(&event->remove, cgroup_event_remove);
3167
3168 efile = eventfd_fget(efd);
3169 if (IS_ERR(efile)) {
3170 ret = PTR_ERR(efile);
3171 goto fail;
3172 }
3173
3174 event->eventfd = eventfd_ctx_fileget(efile);
3175 if (IS_ERR(event->eventfd)) {
3176 ret = PTR_ERR(event->eventfd);
3177 goto fail;
3178 }
3179
3180 cfile = fget(cfd);
3181 if (!cfile) {
3182 ret = -EBADF;
3183 goto fail;
3184 }
3185
3186 /* the process need read permission on control file */
3187 ret = file_permission(cfile, MAY_READ);
3188 if (ret < 0)
3189 goto fail;
3190
3191 event->cft = __file_cft(cfile);
3192 if (IS_ERR(event->cft)) {
3193 ret = PTR_ERR(event->cft);
3194 goto fail;
3195 }
3196
3197 if (!event->cft->register_event || !event->cft->unregister_event) {
3198 ret = -EINVAL;
3199 goto fail;
3200 }
3201
3202 ret = event->cft->register_event(cgrp, event->cft,
3203 event->eventfd, buffer);
3204 if (ret)
3205 goto fail;
3206
3207 if (efile->f_op->poll(efile, &event->pt) & POLLHUP) {
3208 event->cft->unregister_event(cgrp, event->cft, event->eventfd);
3209 ret = 0;
3210 goto fail;
3211 }
3212
Kirill A. Shutemova0a4db52010-03-10 15:22:34 -08003213 /*
3214 * Events should be removed after rmdir of cgroup directory, but before
3215 * destroying subsystem state objects. Let's take reference to cgroup
3216 * directory dentry to do that.
3217 */
3218 dget(cgrp->dentry);
3219
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08003220 spin_lock(&cgrp->event_list_lock);
3221 list_add(&event->list, &cgrp->event_list);
3222 spin_unlock(&cgrp->event_list_lock);
3223
3224 fput(cfile);
3225 fput(efile);
3226
3227 return 0;
3228
3229fail:
3230 if (cfile)
3231 fput(cfile);
3232
3233 if (event && event->eventfd && !IS_ERR(event->eventfd))
3234 eventfd_ctx_put(event->eventfd);
3235
3236 if (!IS_ERR_OR_NULL(efile))
3237 fput(efile);
3238
3239 kfree(event);
3240
3241 return ret;
3242}
3243
Daniel Lezcano97978e62010-10-27 15:33:35 -07003244static u64 cgroup_clone_children_read(struct cgroup *cgrp,
3245 struct cftype *cft)
3246{
3247 return clone_children(cgrp);
3248}
3249
3250static int cgroup_clone_children_write(struct cgroup *cgrp,
3251 struct cftype *cft,
3252 u64 val)
3253{
3254 if (val)
3255 set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags);
3256 else
3257 clear_bit(CGRP_CLONE_CHILDREN, &cgrp->flags);
3258 return 0;
3259}
3260
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08003261/*
Paul Menagebbcb81d2007-10-18 23:39:32 -07003262 * for the common functions, 'private' gives the type of file
3263 */
Ben Blum102a7752009-09-23 15:56:26 -07003264/* for hysterical raisins, we can't put this on the older files */
3265#define CGROUP_FILE_GENERIC_PREFIX "cgroup."
Paul Menage81a6a5c2007-10-18 23:39:38 -07003266static struct cftype files[] = {
3267 {
3268 .name = "tasks",
3269 .open = cgroup_tasks_open,
Paul Menageaf351022008-07-25 01:47:01 -07003270 .write_u64 = cgroup_tasks_write,
Ben Blum102a7752009-09-23 15:56:26 -07003271 .release = cgroup_pidlist_release,
Li Zefan099fca32009-04-02 16:57:29 -07003272 .mode = S_IRUGO | S_IWUSR,
Paul Menage81a6a5c2007-10-18 23:39:38 -07003273 },
Ben Blum102a7752009-09-23 15:56:26 -07003274 {
3275 .name = CGROUP_FILE_GENERIC_PREFIX "procs",
3276 .open = cgroup_procs_open,
3277 /* .write_u64 = cgroup_procs_write, TODO */
3278 .release = cgroup_pidlist_release,
3279 .mode = S_IRUGO,
3280 },
Paul Menage81a6a5c2007-10-18 23:39:38 -07003281 {
3282 .name = "notify_on_release",
Paul Menagef4c753b2008-04-29 00:59:56 -07003283 .read_u64 = cgroup_read_notify_on_release,
Paul Menage6379c102008-07-25 01:47:01 -07003284 .write_u64 = cgroup_write_notify_on_release,
Paul Menage81a6a5c2007-10-18 23:39:38 -07003285 },
Kirill A. Shutemov0dea1162010-03-10 15:22:20 -08003286 {
3287 .name = CGROUP_FILE_GENERIC_PREFIX "event_control",
3288 .write_string = cgroup_write_event_control,
3289 .mode = S_IWUGO,
3290 },
Daniel Lezcano97978e62010-10-27 15:33:35 -07003291 {
3292 .name = "cgroup.clone_children",
3293 .read_u64 = cgroup_clone_children_read,
3294 .write_u64 = cgroup_clone_children_write,
3295 },
Paul Menage81a6a5c2007-10-18 23:39:38 -07003296};
3297
3298static struct cftype cft_release_agent = {
3299 .name = "release_agent",
Paul Menagee788e062008-07-25 01:46:59 -07003300 .read_seq_string = cgroup_release_agent_show,
3301 .write_string = cgroup_release_agent_write,
3302 .max_write_len = PATH_MAX,
Paul Menagebbcb81d2007-10-18 23:39:32 -07003303};
3304
Paul Menagebd89aab2007-10-18 23:40:44 -07003305static int cgroup_populate_dir(struct cgroup *cgrp)
Paul Menageddbcc7e2007-10-18 23:39:30 -07003306{
3307 int err;
3308 struct cgroup_subsys *ss;
3309
3310 /* First clear out any existing files */
Paul Menagebd89aab2007-10-18 23:40:44 -07003311 cgroup_clear_directory(cgrp->dentry);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003312
Paul Menagebd89aab2007-10-18 23:40:44 -07003313 err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files));
Paul Menagebbcb81d2007-10-18 23:39:32 -07003314 if (err < 0)
3315 return err;
3316
Paul Menagebd89aab2007-10-18 23:40:44 -07003317 if (cgrp == cgrp->top_cgroup) {
3318 if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0)
Paul Menage81a6a5c2007-10-18 23:39:38 -07003319 return err;
3320 }
3321
Paul Menagebd89aab2007-10-18 23:40:44 -07003322 for_each_subsys(cgrp->root, ss) {
3323 if (ss->populate && (err = ss->populate(ss, cgrp)) < 0)
Paul Menageddbcc7e2007-10-18 23:39:30 -07003324 return err;
3325 }
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07003326 /* This cgroup is ready now */
3327 for_each_subsys(cgrp->root, ss) {
3328 struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
3329 /*
3330 * Update id->css pointer and make this css visible from
3331 * CSS ID functions. This pointer will be dereferened
3332 * from RCU-read-side without locks.
3333 */
3334 if (css->id)
3335 rcu_assign_pointer(css->id->css, css);
3336 }
Paul Menageddbcc7e2007-10-18 23:39:30 -07003337
3338 return 0;
3339}
3340
3341static void init_cgroup_css(struct cgroup_subsys_state *css,
3342 struct cgroup_subsys *ss,
Paul Menagebd89aab2007-10-18 23:40:44 -07003343 struct cgroup *cgrp)
Paul Menageddbcc7e2007-10-18 23:39:30 -07003344{
Paul Menagebd89aab2007-10-18 23:40:44 -07003345 css->cgroup = cgrp;
Paul Menagee7c5ec92009-01-07 18:08:38 -08003346 atomic_set(&css->refcnt, 1);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003347 css->flags = 0;
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07003348 css->id = NULL;
Paul Menagebd89aab2007-10-18 23:40:44 -07003349 if (cgrp == dummytop)
Paul Menageddbcc7e2007-10-18 23:39:30 -07003350 set_bit(CSS_ROOT, &css->flags);
Paul Menagebd89aab2007-10-18 23:40:44 -07003351 BUG_ON(cgrp->subsys[ss->subsys_id]);
3352 cgrp->subsys[ss->subsys_id] = css;
Paul Menageddbcc7e2007-10-18 23:39:30 -07003353}
3354
Paul Menage999cd8a2009-01-07 18:08:36 -08003355static void cgroup_lock_hierarchy(struct cgroupfs_root *root)
3356{
3357 /* We need to take each hierarchy_mutex in a consistent order */
3358 int i;
3359
Ben Blumaae8aab2010-03-10 15:22:07 -08003360 /*
3361 * No worry about a race with rebind_subsystems that might mess up the
3362 * locking order, since both parties are under cgroup_mutex.
3363 */
Paul Menage999cd8a2009-01-07 18:08:36 -08003364 for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
3365 struct cgroup_subsys *ss = subsys[i];
Ben Blumaae8aab2010-03-10 15:22:07 -08003366 if (ss == NULL)
3367 continue;
Paul Menage999cd8a2009-01-07 18:08:36 -08003368 if (ss->root == root)
Li Zefancfebe562009-02-11 13:04:36 -08003369 mutex_lock(&ss->hierarchy_mutex);
Paul Menage999cd8a2009-01-07 18:08:36 -08003370 }
3371}
3372
3373static void cgroup_unlock_hierarchy(struct cgroupfs_root *root)
3374{
3375 int i;
3376
3377 for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
3378 struct cgroup_subsys *ss = subsys[i];
Ben Blumaae8aab2010-03-10 15:22:07 -08003379 if (ss == NULL)
3380 continue;
Paul Menage999cd8a2009-01-07 18:08:36 -08003381 if (ss->root == root)
3382 mutex_unlock(&ss->hierarchy_mutex);
3383 }
3384}
3385
Paul Menageddbcc7e2007-10-18 23:39:30 -07003386/*
Li Zefana043e3b2008-02-23 15:24:09 -08003387 * cgroup_create - create a cgroup
3388 * @parent: cgroup that will be parent of the new cgroup
3389 * @dentry: dentry of the new cgroup
3390 * @mode: mode to set on new inode
Paul Menageddbcc7e2007-10-18 23:39:30 -07003391 *
Li Zefana043e3b2008-02-23 15:24:09 -08003392 * Must be called with the mutex on the parent inode held
Paul Menageddbcc7e2007-10-18 23:39:30 -07003393 */
Paul Menageddbcc7e2007-10-18 23:39:30 -07003394static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
Li Zefan099fca32009-04-02 16:57:29 -07003395 mode_t mode)
Paul Menageddbcc7e2007-10-18 23:39:30 -07003396{
Paul Menagebd89aab2007-10-18 23:40:44 -07003397 struct cgroup *cgrp;
Paul Menageddbcc7e2007-10-18 23:39:30 -07003398 struct cgroupfs_root *root = parent->root;
3399 int err = 0;
3400 struct cgroup_subsys *ss;
3401 struct super_block *sb = root->sb;
3402
Paul Menagebd89aab2007-10-18 23:40:44 -07003403 cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
3404 if (!cgrp)
Paul Menageddbcc7e2007-10-18 23:39:30 -07003405 return -ENOMEM;
3406
3407 /* Grab a reference on the superblock so the hierarchy doesn't
3408 * get deleted on unmount if there are child cgroups. This
3409 * can be done outside cgroup_mutex, since the sb can't
3410 * disappear while someone has an open control file on the
3411 * fs */
3412 atomic_inc(&sb->s_active);
3413
3414 mutex_lock(&cgroup_mutex);
3415
Paul Menagecc31edc2008-10-18 20:28:04 -07003416 init_cgroup_housekeeping(cgrp);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003417
Paul Menagebd89aab2007-10-18 23:40:44 -07003418 cgrp->parent = parent;
3419 cgrp->root = parent->root;
3420 cgrp->top_cgroup = parent->top_cgroup;
Paul Menageddbcc7e2007-10-18 23:39:30 -07003421
Li Zefanb6abdb02008-03-04 14:28:19 -08003422 if (notify_on_release(parent))
3423 set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
3424
Daniel Lezcano97978e62010-10-27 15:33:35 -07003425 if (clone_children(parent))
3426 set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags);
3427
Paul Menageddbcc7e2007-10-18 23:39:30 -07003428 for_each_subsys(root, ss) {
Paul Menagebd89aab2007-10-18 23:40:44 -07003429 struct cgroup_subsys_state *css = ss->create(ss, cgrp);
Li Zefan4528fd02010-02-02 13:44:10 -08003430
Paul Menageddbcc7e2007-10-18 23:39:30 -07003431 if (IS_ERR(css)) {
3432 err = PTR_ERR(css);
3433 goto err_destroy;
3434 }
Paul Menagebd89aab2007-10-18 23:40:44 -07003435 init_cgroup_css(css, ss, cgrp);
Li Zefan4528fd02010-02-02 13:44:10 -08003436 if (ss->use_id) {
3437 err = alloc_css_id(ss, parent, cgrp);
3438 if (err)
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07003439 goto err_destroy;
Li Zefan4528fd02010-02-02 13:44:10 -08003440 }
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07003441 /* At error, ->destroy() callback has to free assigned ID. */
Daniel Lezcano97978e62010-10-27 15:33:35 -07003442 if (clone_children(parent) && ss->post_clone)
3443 ss->post_clone(ss, cgrp);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003444 }
3445
Paul Menage999cd8a2009-01-07 18:08:36 -08003446 cgroup_lock_hierarchy(root);
Paul Menagebd89aab2007-10-18 23:40:44 -07003447 list_add(&cgrp->sibling, &cgrp->parent->children);
Paul Menage999cd8a2009-01-07 18:08:36 -08003448 cgroup_unlock_hierarchy(root);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003449 root->number_of_cgroups++;
3450
Paul Menagebd89aab2007-10-18 23:40:44 -07003451 err = cgroup_create_dir(cgrp, dentry, mode);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003452 if (err < 0)
3453 goto err_remove;
3454
3455 /* The cgroup directory was pre-locked for us */
Paul Menagebd89aab2007-10-18 23:40:44 -07003456 BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex));
Paul Menageddbcc7e2007-10-18 23:39:30 -07003457
Paul Menagebd89aab2007-10-18 23:40:44 -07003458 err = cgroup_populate_dir(cgrp);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003459 /* If err < 0, we have a half-filled directory - oh well ;) */
3460
3461 mutex_unlock(&cgroup_mutex);
Paul Menagebd89aab2007-10-18 23:40:44 -07003462 mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003463
3464 return 0;
3465
3466 err_remove:
3467
KAMEZAWA Hiroyukibaef99a2009-01-29 14:25:10 -08003468 cgroup_lock_hierarchy(root);
Paul Menagebd89aab2007-10-18 23:40:44 -07003469 list_del(&cgrp->sibling);
KAMEZAWA Hiroyukibaef99a2009-01-29 14:25:10 -08003470 cgroup_unlock_hierarchy(root);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003471 root->number_of_cgroups--;
3472
3473 err_destroy:
3474
3475 for_each_subsys(root, ss) {
Paul Menagebd89aab2007-10-18 23:40:44 -07003476 if (cgrp->subsys[ss->subsys_id])
3477 ss->destroy(ss, cgrp);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003478 }
3479
3480 mutex_unlock(&cgroup_mutex);
3481
3482 /* Release the reference count that we took on the superblock */
3483 deactivate_super(sb);
3484
Paul Menagebd89aab2007-10-18 23:40:44 -07003485 kfree(cgrp);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003486 return err;
3487}
3488
3489static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode)
3490{
3491 struct cgroup *c_parent = dentry->d_parent->d_fsdata;
3492
3493 /* the vfs holds inode->i_mutex already */
3494 return cgroup_create(c_parent, dentry, mode | S_IFDIR);
3495}
3496
Li Zefan55b6fd02008-07-29 22:33:20 -07003497static int cgroup_has_css_refs(struct cgroup *cgrp)
Paul Menage81a6a5c2007-10-18 23:39:38 -07003498{
3499 /* Check the reference count on each subsystem. Since we
3500 * already established that there are no tasks in the
Paul Menagee7c5ec92009-01-07 18:08:38 -08003501 * cgroup, if the css refcount is also 1, then there should
Paul Menage81a6a5c2007-10-18 23:39:38 -07003502 * be no outstanding references, so the subsystem is safe to
3503 * destroy. We scan across all subsystems rather than using
3504 * the per-hierarchy linked list of mounted subsystems since
3505 * we can be called via check_for_release() with no
3506 * synchronization other than RCU, and the subsystem linked
3507 * list isn't RCU-safe */
3508 int i;
Ben Blumaae8aab2010-03-10 15:22:07 -08003509 /*
3510 * We won't need to lock the subsys array, because the subsystems
3511 * we're concerned about aren't going anywhere since our cgroup root
3512 * has a reference on them.
3513 */
Paul Menage81a6a5c2007-10-18 23:39:38 -07003514 for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
3515 struct cgroup_subsys *ss = subsys[i];
3516 struct cgroup_subsys_state *css;
Ben Blumaae8aab2010-03-10 15:22:07 -08003517 /* Skip subsystems not present or not in this hierarchy */
3518 if (ss == NULL || ss->root != cgrp->root)
Paul Menage81a6a5c2007-10-18 23:39:38 -07003519 continue;
Paul Menagebd89aab2007-10-18 23:40:44 -07003520 css = cgrp->subsys[ss->subsys_id];
Paul Menage81a6a5c2007-10-18 23:39:38 -07003521 /* When called from check_for_release() it's possible
3522 * that by this point the cgroup has been removed
3523 * and the css deleted. But a false-positive doesn't
3524 * matter, since it can only happen if the cgroup
3525 * has been deleted and hence no longer needs the
3526 * release agent to be called anyway. */
Paul Menagee7c5ec92009-01-07 18:08:38 -08003527 if (css && (atomic_read(&css->refcnt) > 1))
Paul Menage81a6a5c2007-10-18 23:39:38 -07003528 return 1;
Paul Menage81a6a5c2007-10-18 23:39:38 -07003529 }
3530 return 0;
3531}
3532
Paul Menagee7c5ec92009-01-07 18:08:38 -08003533/*
3534 * Atomically mark all (or else none) of the cgroup's CSS objects as
3535 * CSS_REMOVED. Return true on success, or false if the cgroup has
3536 * busy subsystems. Call with cgroup_mutex held
3537 */
3538
3539static int cgroup_clear_css_refs(struct cgroup *cgrp)
3540{
3541 struct cgroup_subsys *ss;
3542 unsigned long flags;
3543 bool failed = false;
3544 local_irq_save(flags);
3545 for_each_subsys(cgrp->root, ss) {
3546 struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
3547 int refcnt;
Paul Menage804b3c22009-01-29 14:25:21 -08003548 while (1) {
Paul Menagee7c5ec92009-01-07 18:08:38 -08003549 /* We can only remove a CSS with a refcnt==1 */
3550 refcnt = atomic_read(&css->refcnt);
3551 if (refcnt > 1) {
3552 failed = true;
3553 goto done;
3554 }
3555 BUG_ON(!refcnt);
3556 /*
3557 * Drop the refcnt to 0 while we check other
3558 * subsystems. This will cause any racing
3559 * css_tryget() to spin until we set the
3560 * CSS_REMOVED bits or abort
3561 */
Paul Menage804b3c22009-01-29 14:25:21 -08003562 if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt)
3563 break;
3564 cpu_relax();
3565 }
Paul Menagee7c5ec92009-01-07 18:08:38 -08003566 }
3567 done:
3568 for_each_subsys(cgrp->root, ss) {
3569 struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
3570 if (failed) {
3571 /*
3572 * Restore old refcnt if we previously managed
3573 * to clear it from 1 to 0
3574 */
3575 if (!atomic_read(&css->refcnt))
3576 atomic_set(&css->refcnt, 1);
3577 } else {
3578 /* Commit the fact that the CSS is removed */
3579 set_bit(CSS_REMOVED, &css->flags);
3580 }
3581 }
3582 local_irq_restore(flags);
3583 return !failed;
3584}
3585
Paul Menageddbcc7e2007-10-18 23:39:30 -07003586static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
3587{
Paul Menagebd89aab2007-10-18 23:40:44 -07003588 struct cgroup *cgrp = dentry->d_fsdata;
Paul Menageddbcc7e2007-10-18 23:39:30 -07003589 struct dentry *d;
3590 struct cgroup *parent;
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07003591 DEFINE_WAIT(wait);
Kirill A. Shutemov4ab78682010-03-10 15:22:34 -08003592 struct cgroup_event *event, *tmp;
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07003593 int ret;
Paul Menageddbcc7e2007-10-18 23:39:30 -07003594
3595 /* the vfs holds both inode->i_mutex already */
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07003596again:
Paul Menageddbcc7e2007-10-18 23:39:30 -07003597 mutex_lock(&cgroup_mutex);
Paul Menagebd89aab2007-10-18 23:40:44 -07003598 if (atomic_read(&cgrp->count) != 0) {
Paul Menageddbcc7e2007-10-18 23:39:30 -07003599 mutex_unlock(&cgroup_mutex);
3600 return -EBUSY;
3601 }
Paul Menagebd89aab2007-10-18 23:40:44 -07003602 if (!list_empty(&cgrp->children)) {
Paul Menageddbcc7e2007-10-18 23:39:30 -07003603 mutex_unlock(&cgroup_mutex);
3604 return -EBUSY;
3605 }
KAMEZAWA Hiroyuki3fa59df2008-11-19 15:36:34 -08003606 mutex_unlock(&cgroup_mutex);
Li Zefana043e3b2008-02-23 15:24:09 -08003607
KAMEZAWA Hiroyuki4fca88c2008-02-07 00:14:27 -08003608 /*
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -07003609 * In general, subsystem has no css->refcnt after pre_destroy(). But
3610 * in racy cases, subsystem may have to get css->refcnt after
3611 * pre_destroy() and it makes rmdir return with -EBUSY. This sometimes
3612 * make rmdir return -EBUSY too often. To avoid that, we use waitqueue
3613 * for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir
3614 * and subsystem's reference count handling. Please see css_get/put
3615 * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation.
3616 */
3617 set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
3618
3619 /*
Li Zefana043e3b2008-02-23 15:24:09 -08003620 * Call pre_destroy handlers of subsys. Notify subsystems
3621 * that rmdir() request comes.
KAMEZAWA Hiroyuki4fca88c2008-02-07 00:14:27 -08003622 */
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07003623 ret = cgroup_call_pre_destroy(cgrp);
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -07003624 if (ret) {
3625 clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07003626 return ret;
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -07003627 }
Paul Menageddbcc7e2007-10-18 23:39:30 -07003628
KAMEZAWA Hiroyuki3fa59df2008-11-19 15:36:34 -08003629 mutex_lock(&cgroup_mutex);
3630 parent = cgrp->parent;
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07003631 if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) {
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -07003632 clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003633 mutex_unlock(&cgroup_mutex);
3634 return -EBUSY;
3635 }
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07003636 prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE);
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07003637 if (!cgroup_clear_css_refs(cgrp)) {
3638 mutex_unlock(&cgroup_mutex);
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -07003639 /*
3640 * Because someone may call cgroup_wakeup_rmdir_waiter() before
3641 * prepare_to_wait(), we need to check this flag.
3642 */
3643 if (test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags))
3644 schedule();
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07003645 finish_wait(&cgroup_rmdir_waitq, &wait);
3646 clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
3647 if (signal_pending(current))
3648 return -EINTR;
3649 goto again;
3650 }
3651 /* NO css_tryget() can success after here. */
3652 finish_wait(&cgroup_rmdir_waitq, &wait);
3653 clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003654
Paul Menage81a6a5c2007-10-18 23:39:38 -07003655 spin_lock(&release_list_lock);
Paul Menagebd89aab2007-10-18 23:40:44 -07003656 set_bit(CGRP_REMOVED, &cgrp->flags);
3657 if (!list_empty(&cgrp->release_list))
3658 list_del(&cgrp->release_list);
Paul Menage81a6a5c2007-10-18 23:39:38 -07003659 spin_unlock(&release_list_lock);
Paul Menage999cd8a2009-01-07 18:08:36 -08003660
3661 cgroup_lock_hierarchy(cgrp->root);
3662 /* delete this cgroup from parent->children */
Paul Menagebd89aab2007-10-18 23:40:44 -07003663 list_del(&cgrp->sibling);
Paul Menage999cd8a2009-01-07 18:08:36 -08003664 cgroup_unlock_hierarchy(cgrp->root);
3665
Paul Menagebd89aab2007-10-18 23:40:44 -07003666 d = dget(cgrp->dentry);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003667
3668 cgroup_d_remove_dir(d);
3669 dput(d);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003670
Paul Menagebd89aab2007-10-18 23:40:44 -07003671 set_bit(CGRP_RELEASABLE, &parent->flags);
Paul Menage81a6a5c2007-10-18 23:39:38 -07003672 check_for_release(parent);
3673
Kirill A. Shutemov4ab78682010-03-10 15:22:34 -08003674 /*
3675 * Unregister events and notify userspace.
3676 * Notify userspace about cgroup removing only after rmdir of cgroup
3677 * directory to avoid race between userspace and kernelspace
3678 */
3679 spin_lock(&cgrp->event_list_lock);
3680 list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) {
3681 list_del(&event->list);
3682 remove_wait_queue(event->wqh, &event->wait);
3683 eventfd_signal(event->eventfd, 1);
3684 schedule_work(&event->remove);
3685 }
3686 spin_unlock(&cgrp->event_list_lock);
3687
Paul Menageddbcc7e2007-10-18 23:39:30 -07003688 mutex_unlock(&cgroup_mutex);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003689 return 0;
3690}
3691
Li Zefan06a11922008-04-29 01:00:07 -07003692static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
Paul Menageddbcc7e2007-10-18 23:39:30 -07003693{
Paul Menageddbcc7e2007-10-18 23:39:30 -07003694 struct cgroup_subsys_state *css;
Diego Callejacfe36bd2007-11-14 16:58:54 -08003695
3696 printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003697
3698 /* Create the top cgroup state for this subsystem */
Li Zefan33a68ac2009-01-07 18:07:42 -08003699 list_add(&ss->sibling, &rootnode.subsys_list);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003700 ss->root = &rootnode;
3701 css = ss->create(ss, dummytop);
3702 /* We don't handle early failures gracefully */
3703 BUG_ON(IS_ERR(css));
3704 init_cgroup_css(css, ss, dummytop);
3705
Li Zefane8d55fd2008-04-29 01:00:13 -07003706 /* Update the init_css_set to contain a subsys
Paul Menage817929e2007-10-18 23:39:36 -07003707 * pointer to this state - since the subsystem is
Li Zefane8d55fd2008-04-29 01:00:13 -07003708 * newly registered, all tasks and hence the
3709 * init_css_set is in the subsystem's top cgroup. */
3710 init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id];
Paul Menageddbcc7e2007-10-18 23:39:30 -07003711
3712 need_forkexit_callback |= ss->fork || ss->exit;
3713
Li Zefane8d55fd2008-04-29 01:00:13 -07003714 /* At system boot, before all subsystems have been
3715 * registered, no tasks have been forked, so we don't
3716 * need to invoke fork callbacks here. */
3717 BUG_ON(!list_empty(&init_task.tasks));
3718
Paul Menage999cd8a2009-01-07 18:08:36 -08003719 mutex_init(&ss->hierarchy_mutex);
Li Zefancfebe562009-02-11 13:04:36 -08003720 lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003721 ss->active = 1;
Ben Blume6a11052010-03-10 15:22:09 -08003722
3723 /* this function shouldn't be used with modular subsystems, since they
3724 * need to register a subsys_id, among other things */
3725 BUG_ON(ss->module);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003726}
3727
3728/**
Ben Blume6a11052010-03-10 15:22:09 -08003729 * cgroup_load_subsys: load and register a modular subsystem at runtime
3730 * @ss: the subsystem to load
3731 *
3732 * This function should be called in a modular subsystem's initcall. If the
Thomas Weber88393162010-03-16 11:47:56 +01003733 * subsystem is built as a module, it will be assigned a new subsys_id and set
Ben Blume6a11052010-03-10 15:22:09 -08003734 * up for use. If the subsystem is built-in anyway, work is delegated to the
3735 * simpler cgroup_init_subsys.
3736 */
3737int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
3738{
3739 int i;
3740 struct cgroup_subsys_state *css;
3741
3742 /* check name and function validity */
3743 if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN ||
3744 ss->create == NULL || ss->destroy == NULL)
3745 return -EINVAL;
3746
3747 /*
3748 * we don't support callbacks in modular subsystems. this check is
3749 * before the ss->module check for consistency; a subsystem that could
3750 * be a module should still have no callbacks even if the user isn't
3751 * compiling it as one.
3752 */
3753 if (ss->fork || ss->exit)
3754 return -EINVAL;
3755
3756 /*
3757 * an optionally modular subsystem is built-in: we want to do nothing,
3758 * since cgroup_init_subsys will have already taken care of it.
3759 */
3760 if (ss->module == NULL) {
3761 /* a few sanity checks */
3762 BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT);
3763 BUG_ON(subsys[ss->subsys_id] != ss);
3764 return 0;
3765 }
3766
3767 /*
3768 * need to register a subsys id before anything else - for example,
3769 * init_cgroup_css needs it.
3770 */
3771 mutex_lock(&cgroup_mutex);
3772 /* find the first empty slot in the array */
3773 for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
3774 if (subsys[i] == NULL)
3775 break;
3776 }
3777 if (i == CGROUP_SUBSYS_COUNT) {
3778 /* maximum number of subsystems already registered! */
3779 mutex_unlock(&cgroup_mutex);
3780 return -EBUSY;
3781 }
3782 /* assign ourselves the subsys_id */
3783 ss->subsys_id = i;
3784 subsys[i] = ss;
3785
3786 /*
3787 * no ss->create seems to need anything important in the ss struct, so
3788 * this can happen first (i.e. before the rootnode attachment).
3789 */
3790 css = ss->create(ss, dummytop);
3791 if (IS_ERR(css)) {
3792 /* failure case - need to deassign the subsys[] slot. */
3793 subsys[i] = NULL;
3794 mutex_unlock(&cgroup_mutex);
3795 return PTR_ERR(css);
3796 }
3797
3798 list_add(&ss->sibling, &rootnode.subsys_list);
3799 ss->root = &rootnode;
3800
3801 /* our new subsystem will be attached to the dummy hierarchy. */
3802 init_cgroup_css(css, ss, dummytop);
3803 /* init_idr must be after init_cgroup_css because it sets css->id. */
3804 if (ss->use_id) {
3805 int ret = cgroup_init_idr(ss, css);
3806 if (ret) {
3807 dummytop->subsys[ss->subsys_id] = NULL;
3808 ss->destroy(ss, dummytop);
3809 subsys[i] = NULL;
3810 mutex_unlock(&cgroup_mutex);
3811 return ret;
3812 }
3813 }
3814
3815 /*
3816 * Now we need to entangle the css into the existing css_sets. unlike
3817 * in cgroup_init_subsys, there are now multiple css_sets, so each one
3818 * will need a new pointer to it; done by iterating the css_set_table.
3819 * furthermore, modifying the existing css_sets will corrupt the hash
3820 * table state, so each changed css_set will need its hash recomputed.
3821 * this is all done under the css_set_lock.
3822 */
3823 write_lock(&css_set_lock);
3824 for (i = 0; i < CSS_SET_TABLE_SIZE; i++) {
3825 struct css_set *cg;
3826 struct hlist_node *node, *tmp;
3827 struct hlist_head *bucket = &css_set_table[i], *new_bucket;
3828
3829 hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) {
3830 /* skip entries that we already rehashed */
3831 if (cg->subsys[ss->subsys_id])
3832 continue;
3833 /* remove existing entry */
3834 hlist_del(&cg->hlist);
3835 /* set new value */
3836 cg->subsys[ss->subsys_id] = css;
3837 /* recompute hash and restore entry */
3838 new_bucket = css_set_hash(cg->subsys);
3839 hlist_add_head(&cg->hlist, new_bucket);
3840 }
3841 }
3842 write_unlock(&css_set_lock);
3843
3844 mutex_init(&ss->hierarchy_mutex);
3845 lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key);
3846 ss->active = 1;
3847
Ben Blume6a11052010-03-10 15:22:09 -08003848 /* success! */
3849 mutex_unlock(&cgroup_mutex);
3850 return 0;
3851}
3852EXPORT_SYMBOL_GPL(cgroup_load_subsys);
3853
3854/**
Ben Blumcf5d5942010-03-10 15:22:09 -08003855 * cgroup_unload_subsys: unload a modular subsystem
3856 * @ss: the subsystem to unload
3857 *
3858 * This function should be called in a modular subsystem's exitcall. When this
3859 * function is invoked, the refcount on the subsystem's module will be 0, so
3860 * the subsystem will not be attached to any hierarchy.
3861 */
3862void cgroup_unload_subsys(struct cgroup_subsys *ss)
3863{
3864 struct cg_cgroup_link *link;
3865 struct hlist_head *hhead;
3866
3867 BUG_ON(ss->module == NULL);
3868
3869 /*
3870 * we shouldn't be called if the subsystem is in use, and the use of
3871 * try_module_get in parse_cgroupfs_options should ensure that it
3872 * doesn't start being used while we're killing it off.
3873 */
3874 BUG_ON(ss->root != &rootnode);
3875
3876 mutex_lock(&cgroup_mutex);
3877 /* deassign the subsys_id */
3878 BUG_ON(ss->subsys_id < CGROUP_BUILTIN_SUBSYS_COUNT);
3879 subsys[ss->subsys_id] = NULL;
3880
3881 /* remove subsystem from rootnode's list of subsystems */
3882 list_del(&ss->sibling);
3883
3884 /*
3885 * disentangle the css from all css_sets attached to the dummytop. as
3886 * in loading, we need to pay our respects to the hashtable gods.
3887 */
3888 write_lock(&css_set_lock);
3889 list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) {
3890 struct css_set *cg = link->cg;
3891
3892 hlist_del(&cg->hlist);
3893 BUG_ON(!cg->subsys[ss->subsys_id]);
3894 cg->subsys[ss->subsys_id] = NULL;
3895 hhead = css_set_hash(cg->subsys);
3896 hlist_add_head(&cg->hlist, hhead);
3897 }
3898 write_unlock(&css_set_lock);
3899
3900 /*
3901 * remove subsystem's css from the dummytop and free it - need to free
3902 * before marking as null because ss->destroy needs the cgrp->subsys
3903 * pointer to find their state. note that this also takes care of
3904 * freeing the css_id.
3905 */
3906 ss->destroy(ss, dummytop);
3907 dummytop->subsys[ss->subsys_id] = NULL;
3908
3909 mutex_unlock(&cgroup_mutex);
3910}
3911EXPORT_SYMBOL_GPL(cgroup_unload_subsys);
3912
3913/**
Li Zefana043e3b2008-02-23 15:24:09 -08003914 * cgroup_init_early - cgroup initialization at system boot
3915 *
3916 * Initialize cgroups at system boot, and initialize any
3917 * subsystems that request early init.
Paul Menageddbcc7e2007-10-18 23:39:30 -07003918 */
3919int __init cgroup_init_early(void)
3920{
3921 int i;
Lai Jiangshan146aa1b2008-10-18 20:28:03 -07003922 atomic_set(&init_css_set.refcount, 1);
Paul Menage817929e2007-10-18 23:39:36 -07003923 INIT_LIST_HEAD(&init_css_set.cg_links);
3924 INIT_LIST_HEAD(&init_css_set.tasks);
Li Zefan472b1052008-04-29 01:00:11 -07003925 INIT_HLIST_NODE(&init_css_set.hlist);
Paul Menage817929e2007-10-18 23:39:36 -07003926 css_set_count = 1;
Paul Menageddbcc7e2007-10-18 23:39:30 -07003927 init_cgroup_root(&rootnode);
Paul Menage817929e2007-10-18 23:39:36 -07003928 root_count = 1;
3929 init_task.cgroups = &init_css_set;
3930
3931 init_css_set_link.cg = &init_css_set;
Paul Menage7717f7b2009-09-23 15:56:22 -07003932 init_css_set_link.cgrp = dummytop;
Paul Menagebd89aab2007-10-18 23:40:44 -07003933 list_add(&init_css_set_link.cgrp_link_list,
Paul Menage817929e2007-10-18 23:39:36 -07003934 &rootnode.top_cgroup.css_sets);
3935 list_add(&init_css_set_link.cg_link_list,
3936 &init_css_set.cg_links);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003937
Li Zefan472b1052008-04-29 01:00:11 -07003938 for (i = 0; i < CSS_SET_TABLE_SIZE; i++)
3939 INIT_HLIST_HEAD(&css_set_table[i]);
3940
Ben Blumaae8aab2010-03-10 15:22:07 -08003941 /* at bootup time, we don't worry about modular subsystems */
3942 for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
Paul Menageddbcc7e2007-10-18 23:39:30 -07003943 struct cgroup_subsys *ss = subsys[i];
3944
3945 BUG_ON(!ss->name);
3946 BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
3947 BUG_ON(!ss->create);
3948 BUG_ON(!ss->destroy);
3949 if (ss->subsys_id != i) {
Diego Callejacfe36bd2007-11-14 16:58:54 -08003950 printk(KERN_ERR "cgroup: Subsys %s id == %d\n",
Paul Menageddbcc7e2007-10-18 23:39:30 -07003951 ss->name, ss->subsys_id);
3952 BUG();
3953 }
3954
3955 if (ss->early_init)
3956 cgroup_init_subsys(ss);
3957 }
3958 return 0;
3959}
3960
3961/**
Li Zefana043e3b2008-02-23 15:24:09 -08003962 * cgroup_init - cgroup initialization
3963 *
3964 * Register cgroup filesystem and /proc file, and initialize
3965 * any subsystems that didn't request early init.
Paul Menageddbcc7e2007-10-18 23:39:30 -07003966 */
3967int __init cgroup_init(void)
3968{
3969 int err;
3970 int i;
Li Zefan472b1052008-04-29 01:00:11 -07003971 struct hlist_head *hhead;
Paul Menagea4243162007-10-18 23:39:35 -07003972
3973 err = bdi_init(&cgroup_backing_dev_info);
3974 if (err)
3975 return err;
Paul Menageddbcc7e2007-10-18 23:39:30 -07003976
Ben Blumaae8aab2010-03-10 15:22:07 -08003977 /* at bootup time, we don't worry about modular subsystems */
3978 for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
Paul Menageddbcc7e2007-10-18 23:39:30 -07003979 struct cgroup_subsys *ss = subsys[i];
3980 if (!ss->early_init)
3981 cgroup_init_subsys(ss);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07003982 if (ss->use_id)
Ben Blume6a11052010-03-10 15:22:09 -08003983 cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]);
Paul Menageddbcc7e2007-10-18 23:39:30 -07003984 }
3985
Li Zefan472b1052008-04-29 01:00:11 -07003986 /* Add init_css_set to the hash table */
3987 hhead = css_set_hash(init_css_set.subsys);
3988 hlist_add_head(&init_css_set.hlist, hhead);
Paul Menage2c6ab6d2009-09-23 15:56:23 -07003989 BUG_ON(!init_root_id(&rootnode));
Greg KH676db4a2010-08-05 13:53:35 -07003990
3991 cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
3992 if (!cgroup_kobj) {
3993 err = -ENOMEM;
Paul Menageddbcc7e2007-10-18 23:39:30 -07003994 goto out;
Greg KH676db4a2010-08-05 13:53:35 -07003995 }
3996
3997 err = register_filesystem(&cgroup_fs_type);
3998 if (err < 0) {
3999 kobject_put(cgroup_kobj);
4000 goto out;
4001 }
Paul Menageddbcc7e2007-10-18 23:39:30 -07004002
Li Zefan46ae2202008-04-29 01:00:08 -07004003 proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
Paul Menagea4243162007-10-18 23:39:35 -07004004
Paul Menageddbcc7e2007-10-18 23:39:30 -07004005out:
Paul Menagea4243162007-10-18 23:39:35 -07004006 if (err)
4007 bdi_destroy(&cgroup_backing_dev_info);
4008
Paul Menageddbcc7e2007-10-18 23:39:30 -07004009 return err;
4010}
Paul Menageb4f48b62007-10-18 23:39:33 -07004011
Paul Menagea4243162007-10-18 23:39:35 -07004012/*
4013 * proc_cgroup_show()
4014 * - Print task's cgroup paths into seq_file, one line for each hierarchy
4015 * - Used for /proc/<pid>/cgroup.
4016 * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
4017 * doesn't really matter if tsk->cgroup changes after we read it,
Cliff Wickman956db3c2008-02-07 00:14:43 -08004018 * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
Paul Menagea4243162007-10-18 23:39:35 -07004019 * anyway. No need to check that tsk->cgroup != NULL, thanks to
4020 * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
4021 * cgroup to top_cgroup.
4022 */
4023
4024/* TODO: Use a proper seq_file iterator */
4025static int proc_cgroup_show(struct seq_file *m, void *v)
4026{
4027 struct pid *pid;
4028 struct task_struct *tsk;
4029 char *buf;
4030 int retval;
4031 struct cgroupfs_root *root;
4032
4033 retval = -ENOMEM;
4034 buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
4035 if (!buf)
4036 goto out;
4037
4038 retval = -ESRCH;
4039 pid = m->private;
4040 tsk = get_pid_task(pid, PIDTYPE_PID);
4041 if (!tsk)
4042 goto out_free;
4043
4044 retval = 0;
4045
4046 mutex_lock(&cgroup_mutex);
4047
Li Zefane5f6a862009-01-07 18:07:41 -08004048 for_each_active_root(root) {
Paul Menagea4243162007-10-18 23:39:35 -07004049 struct cgroup_subsys *ss;
Paul Menagebd89aab2007-10-18 23:40:44 -07004050 struct cgroup *cgrp;
Paul Menagea4243162007-10-18 23:39:35 -07004051 int count = 0;
4052
Paul Menage2c6ab6d2009-09-23 15:56:23 -07004053 seq_printf(m, "%d:", root->hierarchy_id);
Paul Menagea4243162007-10-18 23:39:35 -07004054 for_each_subsys(root, ss)
4055 seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
Paul Menagec6d57f32009-09-23 15:56:19 -07004056 if (strlen(root->name))
4057 seq_printf(m, "%sname=%s", count ? "," : "",
4058 root->name);
Paul Menagea4243162007-10-18 23:39:35 -07004059 seq_putc(m, ':');
Paul Menage7717f7b2009-09-23 15:56:22 -07004060 cgrp = task_cgroup_from_root(tsk, root);
Paul Menagebd89aab2007-10-18 23:40:44 -07004061 retval = cgroup_path(cgrp, buf, PAGE_SIZE);
Paul Menagea4243162007-10-18 23:39:35 -07004062 if (retval < 0)
4063 goto out_unlock;
4064 seq_puts(m, buf);
4065 seq_putc(m, '\n');
4066 }
4067
4068out_unlock:
4069 mutex_unlock(&cgroup_mutex);
4070 put_task_struct(tsk);
4071out_free:
4072 kfree(buf);
4073out:
4074 return retval;
4075}
4076
4077static int cgroup_open(struct inode *inode, struct file *file)
4078{
4079 struct pid *pid = PROC_I(inode)->pid;
4080 return single_open(file, proc_cgroup_show, pid);
4081}
4082
Alexey Dobriyan828c0952009-10-01 15:43:56 -07004083const struct file_operations proc_cgroup_operations = {
Paul Menagea4243162007-10-18 23:39:35 -07004084 .open = cgroup_open,
4085 .read = seq_read,
4086 .llseek = seq_lseek,
4087 .release = single_release,
4088};
4089
4090/* Display information about each subsystem and each hierarchy */
4091static int proc_cgroupstats_show(struct seq_file *m, void *v)
4092{
4093 int i;
Paul Menagea4243162007-10-18 23:39:35 -07004094
Paul Menage8bab8dd2008-04-04 14:29:57 -07004095 seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
Ben Blumaae8aab2010-03-10 15:22:07 -08004096 /*
4097 * ideally we don't want subsystems moving around while we do this.
4098 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
4099 * subsys/hierarchy state.
4100 */
Paul Menagea4243162007-10-18 23:39:35 -07004101 mutex_lock(&cgroup_mutex);
Paul Menagea4243162007-10-18 23:39:35 -07004102 for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
4103 struct cgroup_subsys *ss = subsys[i];
Ben Blumaae8aab2010-03-10 15:22:07 -08004104 if (ss == NULL)
4105 continue;
Paul Menage2c6ab6d2009-09-23 15:56:23 -07004106 seq_printf(m, "%s\t%d\t%d\t%d\n",
4107 ss->name, ss->root->hierarchy_id,
Paul Menage8bab8dd2008-04-04 14:29:57 -07004108 ss->root->number_of_cgroups, !ss->disabled);
Paul Menagea4243162007-10-18 23:39:35 -07004109 }
4110 mutex_unlock(&cgroup_mutex);
4111 return 0;
4112}
4113
4114static int cgroupstats_open(struct inode *inode, struct file *file)
4115{
Al Viro9dce07f2008-03-29 03:07:28 +00004116 return single_open(file, proc_cgroupstats_show, NULL);
Paul Menagea4243162007-10-18 23:39:35 -07004117}
4118
Alexey Dobriyan828c0952009-10-01 15:43:56 -07004119static const struct file_operations proc_cgroupstats_operations = {
Paul Menagea4243162007-10-18 23:39:35 -07004120 .open = cgroupstats_open,
4121 .read = seq_read,
4122 .llseek = seq_lseek,
4123 .release = single_release,
4124};
4125
Paul Menageb4f48b62007-10-18 23:39:33 -07004126/**
4127 * cgroup_fork - attach newly forked task to its parents cgroup.
Li Zefana043e3b2008-02-23 15:24:09 -08004128 * @child: pointer to task_struct of forking parent process.
Paul Menageb4f48b62007-10-18 23:39:33 -07004129 *
4130 * Description: A task inherits its parent's cgroup at fork().
4131 *
4132 * A pointer to the shared css_set was automatically copied in
4133 * fork.c by dup_task_struct(). However, we ignore that copy, since
4134 * it was not made under the protection of RCU or cgroup_mutex, so
Cliff Wickman956db3c2008-02-07 00:14:43 -08004135 * might no longer be a valid cgroup pointer. cgroup_attach_task() might
Paul Menage817929e2007-10-18 23:39:36 -07004136 * have already changed current->cgroups, allowing the previously
4137 * referenced cgroup group to be removed and freed.
Paul Menageb4f48b62007-10-18 23:39:33 -07004138 *
4139 * At the point that cgroup_fork() is called, 'current' is the parent
4140 * task, and the passed argument 'child' points to the child task.
4141 */
4142void cgroup_fork(struct task_struct *child)
4143{
Paul Menage817929e2007-10-18 23:39:36 -07004144 task_lock(current);
4145 child->cgroups = current->cgroups;
4146 get_css_set(child->cgroups);
4147 task_unlock(current);
4148 INIT_LIST_HEAD(&child->cg_list);
Paul Menageb4f48b62007-10-18 23:39:33 -07004149}
4150
4151/**
Li Zefana043e3b2008-02-23 15:24:09 -08004152 * cgroup_fork_callbacks - run fork callbacks
4153 * @child: the new task
4154 *
4155 * Called on a new task very soon before adding it to the
4156 * tasklist. No need to take any locks since no-one can
4157 * be operating on this task.
Paul Menageb4f48b62007-10-18 23:39:33 -07004158 */
4159void cgroup_fork_callbacks(struct task_struct *child)
4160{
4161 if (need_forkexit_callback) {
4162 int i;
Ben Blumaae8aab2010-03-10 15:22:07 -08004163 /*
4164 * forkexit callbacks are only supported for builtin
4165 * subsystems, and the builtin section of the subsys array is
4166 * immutable, so we don't need to lock the subsys array here.
4167 */
4168 for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
Paul Menageb4f48b62007-10-18 23:39:33 -07004169 struct cgroup_subsys *ss = subsys[i];
4170 if (ss->fork)
4171 ss->fork(ss, child);
4172 }
4173 }
4174}
4175
4176/**
Li Zefana043e3b2008-02-23 15:24:09 -08004177 * cgroup_post_fork - called on a new task after adding it to the task list
4178 * @child: the task in question
4179 *
4180 * Adds the task to the list running through its css_set if necessary.
4181 * Has to be after the task is visible on the task list in case we race
4182 * with the first call to cgroup_iter_start() - to guarantee that the
4183 * new task ends up on its list.
4184 */
Paul Menage817929e2007-10-18 23:39:36 -07004185void cgroup_post_fork(struct task_struct *child)
4186{
4187 if (use_task_css_set_links) {
4188 write_lock(&css_set_lock);
Lai Jiangshanb12b5332009-01-07 18:07:36 -08004189 task_lock(child);
Paul Menage817929e2007-10-18 23:39:36 -07004190 if (list_empty(&child->cg_list))
4191 list_add(&child->cg_list, &child->cgroups->tasks);
Lai Jiangshanb12b5332009-01-07 18:07:36 -08004192 task_unlock(child);
Paul Menage817929e2007-10-18 23:39:36 -07004193 write_unlock(&css_set_lock);
4194 }
4195}
4196/**
Paul Menageb4f48b62007-10-18 23:39:33 -07004197 * cgroup_exit - detach cgroup from exiting task
4198 * @tsk: pointer to task_struct of exiting process
Li Zefana043e3b2008-02-23 15:24:09 -08004199 * @run_callback: run exit callbacks?
Paul Menageb4f48b62007-10-18 23:39:33 -07004200 *
4201 * Description: Detach cgroup from @tsk and release it.
4202 *
4203 * Note that cgroups marked notify_on_release force every task in
4204 * them to take the global cgroup_mutex mutex when exiting.
4205 * This could impact scaling on very large systems. Be reluctant to
4206 * use notify_on_release cgroups where very high task exit scaling
4207 * is required on large systems.
4208 *
4209 * the_top_cgroup_hack:
4210 *
4211 * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
4212 *
4213 * We call cgroup_exit() while the task is still competent to
4214 * handle notify_on_release(), then leave the task attached to the
4215 * root cgroup in each hierarchy for the remainder of its exit.
4216 *
4217 * To do this properly, we would increment the reference count on
4218 * top_cgroup, and near the very end of the kernel/exit.c do_exit()
4219 * code we would add a second cgroup function call, to drop that
4220 * reference. This would just create an unnecessary hot spot on
4221 * the top_cgroup reference count, to no avail.
4222 *
4223 * Normally, holding a reference to a cgroup without bumping its
4224 * count is unsafe. The cgroup could go away, or someone could
4225 * attach us to a different cgroup, decrementing the count on
4226 * the first cgroup that we never incremented. But in this case,
4227 * top_cgroup isn't going away, and either task has PF_EXITING set,
Cliff Wickman956db3c2008-02-07 00:14:43 -08004228 * which wards off any cgroup_attach_task() attempts, or task is a failed
4229 * fork, never visible to cgroup_attach_task.
Paul Menageb4f48b62007-10-18 23:39:33 -07004230 */
4231void cgroup_exit(struct task_struct *tsk, int run_callbacks)
4232{
Paul Menage817929e2007-10-18 23:39:36 -07004233 struct css_set *cg;
Peter Zijlstrad41d5a02011-02-07 17:02:20 +01004234 int i;
Paul Menage817929e2007-10-18 23:39:36 -07004235
4236 /*
4237 * Unlink from the css_set task list if necessary.
4238 * Optimistically check cg_list before taking
4239 * css_set_lock
4240 */
4241 if (!list_empty(&tsk->cg_list)) {
4242 write_lock(&css_set_lock);
4243 if (!list_empty(&tsk->cg_list))
4244 list_del(&tsk->cg_list);
4245 write_unlock(&css_set_lock);
4246 }
4247
Paul Menageb4f48b62007-10-18 23:39:33 -07004248 /* Reassign the task to the init_css_set. */
4249 task_lock(tsk);
Paul Menage817929e2007-10-18 23:39:36 -07004250 cg = tsk->cgroups;
4251 tsk->cgroups = &init_css_set;
Peter Zijlstrad41d5a02011-02-07 17:02:20 +01004252
4253 if (run_callbacks && need_forkexit_callback) {
4254 /*
4255 * modular subsystems can't use callbacks, so no need to lock
4256 * the subsys array
4257 */
4258 for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
4259 struct cgroup_subsys *ss = subsys[i];
4260 if (ss->exit) {
4261 struct cgroup *old_cgrp =
4262 rcu_dereference_raw(cg->subsys[i])->cgroup;
4263 struct cgroup *cgrp = task_cgroup(tsk, i);
4264 ss->exit(ss, cgrp, old_cgrp, tsk);
4265 }
4266 }
4267 }
Paul Menageb4f48b62007-10-18 23:39:33 -07004268 task_unlock(tsk);
Peter Zijlstrad41d5a02011-02-07 17:02:20 +01004269
Paul Menage817929e2007-10-18 23:39:36 -07004270 if (cg)
Paul Menage81a6a5c2007-10-18 23:39:38 -07004271 put_css_set_taskexit(cg);
Paul Menageb4f48b62007-10-18 23:39:33 -07004272}
Paul Menage697f4162007-10-18 23:39:34 -07004273
4274/**
Li Zefana043e3b2008-02-23 15:24:09 -08004275 * cgroup_clone - clone the cgroup the given subsystem is attached to
4276 * @tsk: the task to be moved
4277 * @subsys: the given subsystem
Serge E. Hallyne885dcd2008-07-25 01:47:06 -07004278 * @nodename: the name for the new cgroup
Li Zefana043e3b2008-02-23 15:24:09 -08004279 *
4280 * Duplicate the current cgroup in the hierarchy that the given
4281 * subsystem is attached to, and move this task into the new
4282 * child.
Paul Menage697f4162007-10-18 23:39:34 -07004283 */
Serge E. Hallyne885dcd2008-07-25 01:47:06 -07004284int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
4285 char *nodename)
Paul Menage697f4162007-10-18 23:39:34 -07004286{
4287 struct dentry *dentry;
4288 int ret = 0;
Paul Menage697f4162007-10-18 23:39:34 -07004289 struct cgroup *parent, *child;
4290 struct inode *inode;
4291 struct css_set *cg;
4292 struct cgroupfs_root *root;
4293 struct cgroup_subsys *ss;
4294
4295 /* We shouldn't be called by an unregistered subsystem */
4296 BUG_ON(!subsys->active);
4297
4298 /* First figure out what hierarchy and cgroup we're dealing
4299 * with, and pin them so we can drop cgroup_mutex */
4300 mutex_lock(&cgroup_mutex);
4301 again:
4302 root = subsys->root;
4303 if (root == &rootnode) {
Paul Menage697f4162007-10-18 23:39:34 -07004304 mutex_unlock(&cgroup_mutex);
4305 return 0;
4306 }
Paul Menage697f4162007-10-18 23:39:34 -07004307
Paul Menage697f4162007-10-18 23:39:34 -07004308 /* Pin the hierarchy */
Li Zefan1404f062009-01-29 14:25:21 -08004309 if (!atomic_inc_not_zero(&root->sb->s_active)) {
Li Zefan7b574b72009-01-04 12:00:45 -08004310 /* We race with the final deactivate_super() */
4311 mutex_unlock(&cgroup_mutex);
4312 return 0;
4313 }
Paul Menage697f4162007-10-18 23:39:34 -07004314
Paul Menage817929e2007-10-18 23:39:36 -07004315 /* Keep the cgroup alive */
Li Zefan1404f062009-01-29 14:25:21 -08004316 task_lock(tsk);
4317 parent = task_cgroup(tsk, subsys->subsys_id);
4318 cg = tsk->cgroups;
Paul Menage817929e2007-10-18 23:39:36 -07004319 get_css_set(cg);
Lai Jiangshan104cbd52009-01-07 18:07:38 -08004320 task_unlock(tsk);
Li Zefan1404f062009-01-29 14:25:21 -08004321
Paul Menage697f4162007-10-18 23:39:34 -07004322 mutex_unlock(&cgroup_mutex);
4323
4324 /* Now do the VFS work to create a cgroup */
4325 inode = parent->dentry->d_inode;
4326
4327 /* Hold the parent directory mutex across this operation to
4328 * stop anyone else deleting the new cgroup */
4329 mutex_lock(&inode->i_mutex);
4330 dentry = lookup_one_len(nodename, parent->dentry, strlen(nodename));
4331 if (IS_ERR(dentry)) {
4332 printk(KERN_INFO
Diego Callejacfe36bd2007-11-14 16:58:54 -08004333 "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename,
Paul Menage697f4162007-10-18 23:39:34 -07004334 PTR_ERR(dentry));
4335 ret = PTR_ERR(dentry);
4336 goto out_release;
4337 }
4338
4339 /* Create the cgroup directory, which also creates the cgroup */
Li Zefan75139b82009-01-07 18:07:33 -08004340 ret = vfs_mkdir(inode, dentry, 0755);
Paul Menagebd89aab2007-10-18 23:40:44 -07004341 child = __d_cgrp(dentry);
Paul Menage697f4162007-10-18 23:39:34 -07004342 dput(dentry);
4343 if (ret) {
4344 printk(KERN_INFO
4345 "Failed to create cgroup %s: %d\n", nodename,
4346 ret);
4347 goto out_release;
4348 }
4349
Paul Menage697f4162007-10-18 23:39:34 -07004350 /* The cgroup now exists. Retake cgroup_mutex and check
4351 * that we're still in the same state that we thought we
4352 * were. */
4353 mutex_lock(&cgroup_mutex);
4354 if ((root != subsys->root) ||
4355 (parent != task_cgroup(tsk, subsys->subsys_id))) {
4356 /* Aargh, we raced ... */
4357 mutex_unlock(&inode->i_mutex);
Paul Menage817929e2007-10-18 23:39:36 -07004358 put_css_set(cg);
Paul Menage697f4162007-10-18 23:39:34 -07004359
Li Zefan1404f062009-01-29 14:25:21 -08004360 deactivate_super(root->sb);
Paul Menage697f4162007-10-18 23:39:34 -07004361 /* The cgroup is still accessible in the VFS, but
4362 * we're not going to try to rmdir() it at this
4363 * point. */
4364 printk(KERN_INFO
4365 "Race in cgroup_clone() - leaking cgroup %s\n",
4366 nodename);
4367 goto again;
4368 }
4369
4370 /* do any required auto-setup */
4371 for_each_subsys(root, ss) {
4372 if (ss->post_clone)
4373 ss->post_clone(ss, child);
4374 }
4375
4376 /* All seems fine. Finish by moving the task into the new cgroup */
Cliff Wickman956db3c2008-02-07 00:14:43 -08004377 ret = cgroup_attach_task(child, tsk);
Paul Menage697f4162007-10-18 23:39:34 -07004378 mutex_unlock(&cgroup_mutex);
4379
4380 out_release:
4381 mutex_unlock(&inode->i_mutex);
Paul Menage81a6a5c2007-10-18 23:39:38 -07004382
4383 mutex_lock(&cgroup_mutex);
Paul Menage817929e2007-10-18 23:39:36 -07004384 put_css_set(cg);
Paul Menage81a6a5c2007-10-18 23:39:38 -07004385 mutex_unlock(&cgroup_mutex);
Li Zefan1404f062009-01-29 14:25:21 -08004386 deactivate_super(root->sb);
Paul Menage697f4162007-10-18 23:39:34 -07004387 return ret;
4388}
4389
Li Zefana043e3b2008-02-23 15:24:09 -08004390/**
Grzegorz Nosek313e9242009-04-02 16:57:23 -07004391 * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp
Li Zefana043e3b2008-02-23 15:24:09 -08004392 * @cgrp: the cgroup in question
Grzegorz Nosek313e9242009-04-02 16:57:23 -07004393 * @task: the task in question
Li Zefana043e3b2008-02-23 15:24:09 -08004394 *
Grzegorz Nosek313e9242009-04-02 16:57:23 -07004395 * See if @cgrp is a descendant of @task's cgroup in the appropriate
4396 * hierarchy.
Paul Menage697f4162007-10-18 23:39:34 -07004397 *
4398 * If we are sending in dummytop, then presumably we are creating
4399 * the top cgroup in the subsystem.
4400 *
4401 * Called only by the ns (nsproxy) cgroup.
4402 */
Grzegorz Nosek313e9242009-04-02 16:57:23 -07004403int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task)
Paul Menage697f4162007-10-18 23:39:34 -07004404{
4405 int ret;
4406 struct cgroup *target;
Paul Menage697f4162007-10-18 23:39:34 -07004407
Paul Menagebd89aab2007-10-18 23:40:44 -07004408 if (cgrp == dummytop)
Paul Menage697f4162007-10-18 23:39:34 -07004409 return 1;
4410
Paul Menage7717f7b2009-09-23 15:56:22 -07004411 target = task_cgroup_from_root(task, cgrp->root);
Paul Menagebd89aab2007-10-18 23:40:44 -07004412 while (cgrp != target && cgrp!= cgrp->top_cgroup)
4413 cgrp = cgrp->parent;
4414 ret = (cgrp == target);
Paul Menage697f4162007-10-18 23:39:34 -07004415 return ret;
4416}
Paul Menage81a6a5c2007-10-18 23:39:38 -07004417
Paul Menagebd89aab2007-10-18 23:40:44 -07004418static void check_for_release(struct cgroup *cgrp)
Paul Menage81a6a5c2007-10-18 23:39:38 -07004419{
4420 /* All of these checks rely on RCU to keep the cgroup
4421 * structure alive */
Paul Menagebd89aab2007-10-18 23:40:44 -07004422 if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count)
4423 && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) {
Paul Menage81a6a5c2007-10-18 23:39:38 -07004424 /* Control Group is currently removeable. If it's not
4425 * already queued for a userspace notification, queue
4426 * it now */
4427 int need_schedule_work = 0;
4428 spin_lock(&release_list_lock);
Paul Menagebd89aab2007-10-18 23:40:44 -07004429 if (!cgroup_is_removed(cgrp) &&
4430 list_empty(&cgrp->release_list)) {
4431 list_add(&cgrp->release_list, &release_list);
Paul Menage81a6a5c2007-10-18 23:39:38 -07004432 need_schedule_work = 1;
4433 }
4434 spin_unlock(&release_list_lock);
4435 if (need_schedule_work)
4436 schedule_work(&release_agent_work);
4437 }
4438}
4439
Daisuke Nishimurad7b9fff2010-03-10 15:22:05 -08004440/* Caller must verify that the css is not for root cgroup */
4441void __css_put(struct cgroup_subsys_state *css, int count)
Paul Menage81a6a5c2007-10-18 23:39:38 -07004442{
Paul Menagebd89aab2007-10-18 23:40:44 -07004443 struct cgroup *cgrp = css->cgroup;
KAMEZAWA Hiroyuki3dece832009-10-01 15:44:09 -07004444 int val;
Paul Menage81a6a5c2007-10-18 23:39:38 -07004445 rcu_read_lock();
Daisuke Nishimurad7b9fff2010-03-10 15:22:05 -08004446 val = atomic_sub_return(count, &css->refcnt);
KAMEZAWA Hiroyuki3dece832009-10-01 15:44:09 -07004447 if (val == 1) {
KAMEZAWA Hiroyukiec64f512009-04-02 16:57:26 -07004448 if (notify_on_release(cgrp)) {
4449 set_bit(CGRP_RELEASABLE, &cgrp->flags);
4450 check_for_release(cgrp);
4451 }
KAMEZAWA Hiroyuki88703262009-07-29 15:04:06 -07004452 cgroup_wakeup_rmdir_waiter(cgrp);
Paul Menage81a6a5c2007-10-18 23:39:38 -07004453 }
4454 rcu_read_unlock();
KAMEZAWA Hiroyuki3dece832009-10-01 15:44:09 -07004455 WARN_ON_ONCE(val < 1);
Paul Menage81a6a5c2007-10-18 23:39:38 -07004456}
Ben Blum67523c42010-03-10 15:22:11 -08004457EXPORT_SYMBOL_GPL(__css_put);
Paul Menage81a6a5c2007-10-18 23:39:38 -07004458
4459/*
4460 * Notify userspace when a cgroup is released, by running the
4461 * configured release agent with the name of the cgroup (path
4462 * relative to the root of cgroup file system) as the argument.
4463 *
4464 * Most likely, this user command will try to rmdir this cgroup.
4465 *
4466 * This races with the possibility that some other task will be
4467 * attached to this cgroup before it is removed, or that some other
4468 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
4469 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
4470 * unused, and this cgroup will be reprieved from its death sentence,
4471 * to continue to serve a useful existence. Next time it's released,
4472 * we will get notified again, if it still has 'notify_on_release' set.
4473 *
4474 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
4475 * means only wait until the task is successfully execve()'d. The
4476 * separate release agent task is forked by call_usermodehelper(),
4477 * then control in this thread returns here, without waiting for the
4478 * release agent task. We don't bother to wait because the caller of
4479 * this routine has no use for the exit status of the release agent
4480 * task, so no sense holding our caller up for that.
Paul Menage81a6a5c2007-10-18 23:39:38 -07004481 */
Paul Menage81a6a5c2007-10-18 23:39:38 -07004482static void cgroup_release_agent(struct work_struct *work)
4483{
4484 BUG_ON(work != &release_agent_work);
4485 mutex_lock(&cgroup_mutex);
4486 spin_lock(&release_list_lock);
4487 while (!list_empty(&release_list)) {
4488 char *argv[3], *envp[3];
4489 int i;
Paul Menagee788e062008-07-25 01:46:59 -07004490 char *pathbuf = NULL, *agentbuf = NULL;
Paul Menagebd89aab2007-10-18 23:40:44 -07004491 struct cgroup *cgrp = list_entry(release_list.next,
Paul Menage81a6a5c2007-10-18 23:39:38 -07004492 struct cgroup,
4493 release_list);
Paul Menagebd89aab2007-10-18 23:40:44 -07004494 list_del_init(&cgrp->release_list);
Paul Menage81a6a5c2007-10-18 23:39:38 -07004495 spin_unlock(&release_list_lock);
4496 pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
Paul Menagee788e062008-07-25 01:46:59 -07004497 if (!pathbuf)
4498 goto continue_free;
4499 if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0)
4500 goto continue_free;
4501 agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
4502 if (!agentbuf)
4503 goto continue_free;
Paul Menage81a6a5c2007-10-18 23:39:38 -07004504
4505 i = 0;
Paul Menagee788e062008-07-25 01:46:59 -07004506 argv[i++] = agentbuf;
4507 argv[i++] = pathbuf;
Paul Menage81a6a5c2007-10-18 23:39:38 -07004508 argv[i] = NULL;
4509
4510 i = 0;
4511 /* minimal command environment */
4512 envp[i++] = "HOME=/";
4513 envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
4514 envp[i] = NULL;
4515
4516 /* Drop the lock while we invoke the usermode helper,
4517 * since the exec could involve hitting disk and hence
4518 * be a slow process */
4519 mutex_unlock(&cgroup_mutex);
4520 call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
Paul Menage81a6a5c2007-10-18 23:39:38 -07004521 mutex_lock(&cgroup_mutex);
Paul Menagee788e062008-07-25 01:46:59 -07004522 continue_free:
4523 kfree(pathbuf);
4524 kfree(agentbuf);
Paul Menage81a6a5c2007-10-18 23:39:38 -07004525 spin_lock(&release_list_lock);
4526 }
4527 spin_unlock(&release_list_lock);
4528 mutex_unlock(&cgroup_mutex);
4529}
Paul Menage8bab8dd2008-04-04 14:29:57 -07004530
4531static int __init cgroup_disable(char *str)
4532{
4533 int i;
4534 char *token;
4535
4536 while ((token = strsep(&str, ",")) != NULL) {
4537 if (!*token)
4538 continue;
Ben Blumaae8aab2010-03-10 15:22:07 -08004539 /*
4540 * cgroup_disable, being at boot time, can't know about module
4541 * subsystems, so we don't worry about them.
4542 */
4543 for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
Paul Menage8bab8dd2008-04-04 14:29:57 -07004544 struct cgroup_subsys *ss = subsys[i];
4545
4546 if (!strcmp(token, ss->name)) {
4547 ss->disabled = 1;
4548 printk(KERN_INFO "Disabling %s control group"
4549 " subsystem\n", ss->name);
4550 break;
4551 }
4552 }
4553 }
4554 return 1;
4555}
4556__setup("cgroup_disable=", cgroup_disable);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004557
4558/*
4559 * Functons for CSS ID.
4560 */
4561
4562/*
4563 *To get ID other than 0, this should be called when !cgroup_is_removed().
4564 */
4565unsigned short css_id(struct cgroup_subsys_state *css)
4566{
KAMEZAWA Hiroyuki7f0f1542010-05-11 14:06:58 -07004567 struct css_id *cssid;
4568
4569 /*
4570 * This css_id() can return correct value when somone has refcnt
4571 * on this or this is under rcu_read_lock(). Once css->id is allocated,
4572 * it's unchanged until freed.
4573 */
4574 cssid = rcu_dereference_check(css->id,
4575 rcu_read_lock_held() || atomic_read(&css->refcnt));
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004576
4577 if (cssid)
4578 return cssid->id;
4579 return 0;
4580}
Ben Blum67523c42010-03-10 15:22:11 -08004581EXPORT_SYMBOL_GPL(css_id);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004582
4583unsigned short css_depth(struct cgroup_subsys_state *css)
4584{
KAMEZAWA Hiroyuki7f0f1542010-05-11 14:06:58 -07004585 struct css_id *cssid;
4586
4587 cssid = rcu_dereference_check(css->id,
4588 rcu_read_lock_held() || atomic_read(&css->refcnt));
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004589
4590 if (cssid)
4591 return cssid->depth;
4592 return 0;
4593}
Ben Blum67523c42010-03-10 15:22:11 -08004594EXPORT_SYMBOL_GPL(css_depth);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004595
KAMEZAWA Hiroyuki747388d2010-05-11 14:06:59 -07004596/**
4597 * css_is_ancestor - test "root" css is an ancestor of "child"
4598 * @child: the css to be tested.
4599 * @root: the css supporsed to be an ancestor of the child.
4600 *
4601 * Returns true if "root" is an ancestor of "child" in its hierarchy. Because
4602 * this function reads css->id, this use rcu_dereference() and rcu_read_lock().
4603 * But, considering usual usage, the csses should be valid objects after test.
4604 * Assuming that the caller will do some action to the child if this returns
4605 * returns true, the caller must take "child";s reference count.
4606 * If "child" is valid object and this returns true, "root" is valid, too.
4607 */
4608
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004609bool css_is_ancestor(struct cgroup_subsys_state *child,
KAMEZAWA Hiroyuki0b7f5692009-04-02 16:57:38 -07004610 const struct cgroup_subsys_state *root)
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004611{
KAMEZAWA Hiroyuki747388d2010-05-11 14:06:59 -07004612 struct css_id *child_id;
4613 struct css_id *root_id;
4614 bool ret = true;
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004615
KAMEZAWA Hiroyuki747388d2010-05-11 14:06:59 -07004616 rcu_read_lock();
4617 child_id = rcu_dereference(child->id);
4618 root_id = rcu_dereference(root->id);
4619 if (!child_id
4620 || !root_id
4621 || (child_id->depth < root_id->depth)
4622 || (child_id->stack[root_id->depth] != root_id->id))
4623 ret = false;
4624 rcu_read_unlock();
4625 return ret;
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004626}
4627
4628static void __free_css_id_cb(struct rcu_head *head)
4629{
4630 struct css_id *id;
4631
4632 id = container_of(head, struct css_id, rcu_head);
4633 kfree(id);
4634}
4635
4636void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css)
4637{
4638 struct css_id *id = css->id;
4639 /* When this is called before css_id initialization, id can be NULL */
4640 if (!id)
4641 return;
4642
4643 BUG_ON(!ss->use_id);
4644
4645 rcu_assign_pointer(id->css, NULL);
4646 rcu_assign_pointer(css->id, NULL);
4647 spin_lock(&ss->id_lock);
4648 idr_remove(&ss->idr, id->id);
4649 spin_unlock(&ss->id_lock);
4650 call_rcu(&id->rcu_head, __free_css_id_cb);
4651}
Ben Blum67523c42010-03-10 15:22:11 -08004652EXPORT_SYMBOL_GPL(free_css_id);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004653
4654/*
4655 * This is called by init or create(). Then, calls to this function are
4656 * always serialized (By cgroup_mutex() at create()).
4657 */
4658
4659static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth)
4660{
4661 struct css_id *newid;
4662 int myid, error, size;
4663
4664 BUG_ON(!ss->use_id);
4665
4666 size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1);
4667 newid = kzalloc(size, GFP_KERNEL);
4668 if (!newid)
4669 return ERR_PTR(-ENOMEM);
4670 /* get id */
4671 if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) {
4672 error = -ENOMEM;
4673 goto err_out;
4674 }
4675 spin_lock(&ss->id_lock);
4676 /* Don't use 0. allocates an ID of 1-65535 */
4677 error = idr_get_new_above(&ss->idr, newid, 1, &myid);
4678 spin_unlock(&ss->id_lock);
4679
4680 /* Returns error when there are no free spaces for new ID.*/
4681 if (error) {
4682 error = -ENOSPC;
4683 goto err_out;
4684 }
4685 if (myid > CSS_ID_MAX)
4686 goto remove_idr;
4687
4688 newid->id = myid;
4689 newid->depth = depth;
4690 return newid;
4691remove_idr:
4692 error = -ENOSPC;
4693 spin_lock(&ss->id_lock);
4694 idr_remove(&ss->idr, myid);
4695 spin_unlock(&ss->id_lock);
4696err_out:
4697 kfree(newid);
4698 return ERR_PTR(error);
4699
4700}
4701
Ben Blume6a11052010-03-10 15:22:09 -08004702static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss,
4703 struct cgroup_subsys_state *rootcss)
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004704{
4705 struct css_id *newid;
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004706
4707 spin_lock_init(&ss->id_lock);
4708 idr_init(&ss->idr);
4709
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004710 newid = get_new_cssid(ss, 0);
4711 if (IS_ERR(newid))
4712 return PTR_ERR(newid);
4713
4714 newid->stack[0] = newid->id;
4715 newid->css = rootcss;
4716 rootcss->id = newid;
4717 return 0;
4718}
4719
4720static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent,
4721 struct cgroup *child)
4722{
4723 int subsys_id, i, depth = 0;
4724 struct cgroup_subsys_state *parent_css, *child_css;
Li Zefanfae9c792010-04-22 17:30:00 +08004725 struct css_id *child_id, *parent_id;
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004726
4727 subsys_id = ss->subsys_id;
4728 parent_css = parent->subsys[subsys_id];
4729 child_css = child->subsys[subsys_id];
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004730 parent_id = parent_css->id;
Greg Thelen94b3dd02010-06-04 14:15:03 -07004731 depth = parent_id->depth + 1;
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004732
4733 child_id = get_new_cssid(ss, depth);
4734 if (IS_ERR(child_id))
4735 return PTR_ERR(child_id);
4736
4737 for (i = 0; i < depth; i++)
4738 child_id->stack[i] = parent_id->stack[i];
4739 child_id->stack[depth] = child_id->id;
4740 /*
4741 * child_id->css pointer will be set after this cgroup is available
4742 * see cgroup_populate_dir()
4743 */
4744 rcu_assign_pointer(child_css->id, child_id);
4745
4746 return 0;
4747}
4748
4749/**
4750 * css_lookup - lookup css by id
4751 * @ss: cgroup subsys to be looked into.
4752 * @id: the id
4753 *
4754 * Returns pointer to cgroup_subsys_state if there is valid one with id.
4755 * NULL if not. Should be called under rcu_read_lock()
4756 */
4757struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id)
4758{
4759 struct css_id *cssid = NULL;
4760
4761 BUG_ON(!ss->use_id);
4762 cssid = idr_find(&ss->idr, id);
4763
4764 if (unlikely(!cssid))
4765 return NULL;
4766
4767 return rcu_dereference(cssid->css);
4768}
Ben Blum67523c42010-03-10 15:22:11 -08004769EXPORT_SYMBOL_GPL(css_lookup);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -07004770
4771/**
4772 * css_get_next - lookup next cgroup under specified hierarchy.
4773 * @ss: pointer to subsystem
4774 * @id: current position of iteration.
4775 * @root: pointer to css. search tree under this.
4776 * @foundid: position of found object.
4777 *
4778 * Search next css under the specified hierarchy of rootid. Calling under
4779 * rcu_read_lock() is necessary. Returns NULL if it reaches the end.
4780 */
4781struct cgroup_subsys_state *
4782css_get_next(struct cgroup_subsys *ss, int id,
4783 struct cgroup_subsys_state *root, int *foundid)
4784{
4785 struct cgroup_subsys_state *ret = NULL;
4786 struct css_id *tmp;
4787 int tmpid;
4788 int rootid = css_id(root);
4789 int depth = css_depth(root);
4790
4791 if (!rootid)
4792 return NULL;
4793
4794 BUG_ON(!ss->use_id);
4795 /* fill start point for scan */
4796 tmpid = id;
4797 while (1) {
4798 /*
4799 * scan next entry from bitmap(tree), tmpid is updated after
4800 * idr_get_next().
4801 */
4802 spin_lock(&ss->id_lock);
4803 tmp = idr_get_next(&ss->idr, &tmpid);
4804 spin_unlock(&ss->id_lock);
4805
4806 if (!tmp)
4807 break;
4808 if (tmp->depth >= depth && tmp->stack[depth] == rootid) {
4809 ret = rcu_dereference(tmp->css);
4810 if (ret) {
4811 *foundid = tmpid;
4812 break;
4813 }
4814 }
4815 /* continue to scan from next id */
4816 tmpid = tmpid + 1;
4817 }
4818 return ret;
4819}
4820
Paul Menagefe693432009-09-23 15:56:20 -07004821#ifdef CONFIG_CGROUP_DEBUG
4822static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
4823 struct cgroup *cont)
4824{
4825 struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
4826
4827 if (!css)
4828 return ERR_PTR(-ENOMEM);
4829
4830 return css;
4831}
4832
4833static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
4834{
4835 kfree(cont->subsys[debug_subsys_id]);
4836}
4837
4838static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft)
4839{
4840 return atomic_read(&cont->count);
4841}
4842
4843static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft)
4844{
4845 return cgroup_task_count(cont);
4846}
4847
4848static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft)
4849{
4850 return (u64)(unsigned long)current->cgroups;
4851}
4852
4853static u64 current_css_set_refcount_read(struct cgroup *cont,
4854 struct cftype *cft)
4855{
4856 u64 count;
4857
4858 rcu_read_lock();
4859 count = atomic_read(&current->cgroups->refcount);
4860 rcu_read_unlock();
4861 return count;
4862}
4863
Paul Menage7717f7b2009-09-23 15:56:22 -07004864static int current_css_set_cg_links_read(struct cgroup *cont,
4865 struct cftype *cft,
4866 struct seq_file *seq)
4867{
4868 struct cg_cgroup_link *link;
4869 struct css_set *cg;
4870
4871 read_lock(&css_set_lock);
4872 rcu_read_lock();
4873 cg = rcu_dereference(current->cgroups);
4874 list_for_each_entry(link, &cg->cg_links, cg_link_list) {
4875 struct cgroup *c = link->cgrp;
4876 const char *name;
4877
4878 if (c->dentry)
4879 name = c->dentry->d_name.name;
4880 else
4881 name = "?";
Paul Menage2c6ab6d2009-09-23 15:56:23 -07004882 seq_printf(seq, "Root %d group %s\n",
4883 c->root->hierarchy_id, name);
Paul Menage7717f7b2009-09-23 15:56:22 -07004884 }
4885 rcu_read_unlock();
4886 read_unlock(&css_set_lock);
4887 return 0;
4888}
4889
4890#define MAX_TASKS_SHOWN_PER_CSS 25
4891static int cgroup_css_links_read(struct cgroup *cont,
4892 struct cftype *cft,
4893 struct seq_file *seq)
4894{
4895 struct cg_cgroup_link *link;
4896
4897 read_lock(&css_set_lock);
4898 list_for_each_entry(link, &cont->css_sets, cgrp_link_list) {
4899 struct css_set *cg = link->cg;
4900 struct task_struct *task;
4901 int count = 0;
4902 seq_printf(seq, "css_set %p\n", cg);
4903 list_for_each_entry(task, &cg->tasks, cg_list) {
4904 if (count++ > MAX_TASKS_SHOWN_PER_CSS) {
4905 seq_puts(seq, " ...\n");
4906 break;
4907 } else {
4908 seq_printf(seq, " task %d\n",
4909 task_pid_vnr(task));
4910 }
4911 }
4912 }
4913 read_unlock(&css_set_lock);
4914 return 0;
4915}
4916
Paul Menagefe693432009-09-23 15:56:20 -07004917static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft)
4918{
4919 return test_bit(CGRP_RELEASABLE, &cgrp->flags);
4920}
4921
4922static struct cftype debug_files[] = {
4923 {
4924 .name = "cgroup_refcount",
4925 .read_u64 = cgroup_refcount_read,
4926 },
4927 {
4928 .name = "taskcount",
4929 .read_u64 = debug_taskcount_read,
4930 },
4931
4932 {
4933 .name = "current_css_set",
4934 .read_u64 = current_css_set_read,
4935 },
4936
4937 {
4938 .name = "current_css_set_refcount",
4939 .read_u64 = current_css_set_refcount_read,
4940 },
4941
4942 {
Paul Menage7717f7b2009-09-23 15:56:22 -07004943 .name = "current_css_set_cg_links",
4944 .read_seq_string = current_css_set_cg_links_read,
4945 },
4946
4947 {
4948 .name = "cgroup_css_links",
4949 .read_seq_string = cgroup_css_links_read,
4950 },
4951
4952 {
Paul Menagefe693432009-09-23 15:56:20 -07004953 .name = "releasable",
4954 .read_u64 = releasable_read,
4955 },
4956};
4957
4958static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
4959{
4960 return cgroup_add_files(cont, ss, debug_files,
4961 ARRAY_SIZE(debug_files));
4962}
4963
4964struct cgroup_subsys debug_subsys = {
4965 .name = "debug",
4966 .create = debug_create,
4967 .destroy = debug_destroy,
4968 .populate = debug_populate,
4969 .subsys_id = debug_subsys_id,
4970};
4971#endif /* CONFIG_CGROUP_DEBUG */