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ddbcc7e8 | 1 | /* |
ddbcc7e8 PM |
2 | * Generic process-grouping system. |
3 | * | |
4 | * Based originally on the cpuset system, extracted by Paul Menage | |
5 | * Copyright (C) 2006 Google, Inc | |
6 | * | |
0dea1168 KS |
7 | * Notifications support |
8 | * Copyright (C) 2009 Nokia Corporation | |
9 | * Author: Kirill A. Shutemov | |
10 | * | |
ddbcc7e8 PM |
11 | * Copyright notices from the original cpuset code: |
12 | * -------------------------------------------------- | |
13 | * Copyright (C) 2003 BULL SA. | |
14 | * Copyright (C) 2004-2006 Silicon Graphics, Inc. | |
15 | * | |
16 | * Portions derived from Patrick Mochel's sysfs code. | |
17 | * sysfs is Copyright (c) 2001-3 Patrick Mochel | |
18 | * | |
19 | * 2003-10-10 Written by Simon Derr. | |
20 | * 2003-10-22 Updates by Stephen Hemminger. | |
21 | * 2004 May-July Rework by Paul Jackson. | |
22 | * --------------------------------------------------- | |
23 | * | |
24 | * This file is subject to the terms and conditions of the GNU General Public | |
25 | * License. See the file COPYING in the main directory of the Linux | |
26 | * distribution for more details. | |
27 | */ | |
28 | ||
29 | #include <linux/cgroup.h> | |
2ce9738b | 30 | #include <linux/cred.h> |
c6d57f33 | 31 | #include <linux/ctype.h> |
ddbcc7e8 PM |
32 | #include <linux/errno.h> |
33 | #include <linux/fs.h> | |
2ce9738b | 34 | #include <linux/init_task.h> |
ddbcc7e8 PM |
35 | #include <linux/kernel.h> |
36 | #include <linux/list.h> | |
37 | #include <linux/mm.h> | |
38 | #include <linux/mutex.h> | |
39 | #include <linux/mount.h> | |
40 | #include <linux/pagemap.h> | |
a424316c | 41 | #include <linux/proc_fs.h> |
ddbcc7e8 PM |
42 | #include <linux/rcupdate.h> |
43 | #include <linux/sched.h> | |
817929ec | 44 | #include <linux/backing-dev.h> |
ddbcc7e8 PM |
45 | #include <linux/seq_file.h> |
46 | #include <linux/slab.h> | |
47 | #include <linux/magic.h> | |
48 | #include <linux/spinlock.h> | |
49 | #include <linux/string.h> | |
bbcb81d0 | 50 | #include <linux/sort.h> |
81a6a5cd | 51 | #include <linux/kmod.h> |
e6a1105b | 52 | #include <linux/module.h> |
846c7bb0 BS |
53 | #include <linux/delayacct.h> |
54 | #include <linux/cgroupstats.h> | |
472b1053 | 55 | #include <linux/hash.h> |
3f8206d4 | 56 | #include <linux/namei.h> |
096b7fe0 | 57 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 58 | #include <linux/idr.h> |
d1d9fd33 | 59 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
0dea1168 KS |
60 | #include <linux/eventfd.h> |
61 | #include <linux/poll.h> | |
d846687d | 62 | #include <linux/flex_array.h> /* used in cgroup_attach_proc */ |
846c7bb0 | 63 | |
60063497 | 64 | #include <linux/atomic.h> |
ddbcc7e8 | 65 | |
28b4c27b TH |
66 | /* css deactivation bias, makes css->refcnt negative to deny new trygets */ |
67 | #define CSS_DEACT_BIAS INT_MIN | |
68 | ||
e25e2cbb TH |
69 | /* |
70 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
71 | * hierarchy must be performed while holding it. | |
72 | * | |
73 | * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify | |
74 | * cgroupfs_root of any cgroup hierarchy - subsys list, flags, | |
75 | * release_agent_path and so on. Modifying requires both cgroup_mutex and | |
76 | * cgroup_root_mutex. Readers can acquire either of the two. This is to | |
77 | * break the following locking order cycle. | |
78 | * | |
79 | * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem | |
80 | * B. namespace_sem -> cgroup_mutex | |
81 | * | |
82 | * B happens only through cgroup_show_options() and using cgroup_root_mutex | |
83 | * breaks it. | |
84 | */ | |
81a6a5cd | 85 | static DEFINE_MUTEX(cgroup_mutex); |
e25e2cbb | 86 | static DEFINE_MUTEX(cgroup_root_mutex); |
81a6a5cd | 87 | |
aae8aab4 BB |
88 | /* |
89 | * Generate an array of cgroup subsystem pointers. At boot time, this is | |
90 | * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are | |
91 | * registered after that. The mutable section of this array is protected by | |
92 | * cgroup_mutex. | |
93 | */ | |
ddbcc7e8 | 94 | #define SUBSYS(_x) &_x ## _subsys, |
aae8aab4 | 95 | static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = { |
ddbcc7e8 PM |
96 | #include <linux/cgroup_subsys.h> |
97 | }; | |
98 | ||
c6d57f33 PM |
99 | #define MAX_CGROUP_ROOT_NAMELEN 64 |
100 | ||
ddbcc7e8 PM |
101 | /* |
102 | * A cgroupfs_root represents the root of a cgroup hierarchy, | |
103 | * and may be associated with a superblock to form an active | |
104 | * hierarchy | |
105 | */ | |
106 | struct cgroupfs_root { | |
107 | struct super_block *sb; | |
108 | ||
109 | /* | |
110 | * The bitmask of subsystems intended to be attached to this | |
111 | * hierarchy | |
112 | */ | |
113 | unsigned long subsys_bits; | |
114 | ||
2c6ab6d2 PM |
115 | /* Unique id for this hierarchy. */ |
116 | int hierarchy_id; | |
117 | ||
ddbcc7e8 PM |
118 | /* The bitmask of subsystems currently attached to this hierarchy */ |
119 | unsigned long actual_subsys_bits; | |
120 | ||
121 | /* A list running through the attached subsystems */ | |
122 | struct list_head subsys_list; | |
123 | ||
124 | /* The root cgroup for this hierarchy */ | |
125 | struct cgroup top_cgroup; | |
126 | ||
127 | /* Tracks how many cgroups are currently defined in hierarchy.*/ | |
128 | int number_of_cgroups; | |
129 | ||
e5f6a860 | 130 | /* A list running through the active hierarchies */ |
ddbcc7e8 PM |
131 | struct list_head root_list; |
132 | ||
b0ca5a84 TH |
133 | /* All cgroups on this root, cgroup_mutex protected */ |
134 | struct list_head allcg_list; | |
135 | ||
ddbcc7e8 PM |
136 | /* Hierarchy-specific flags */ |
137 | unsigned long flags; | |
81a6a5cd | 138 | |
e788e066 | 139 | /* The path to use for release notifications. */ |
81a6a5cd | 140 | char release_agent_path[PATH_MAX]; |
c6d57f33 PM |
141 | |
142 | /* The name for this hierarchy - may be empty */ | |
143 | char name[MAX_CGROUP_ROOT_NAMELEN]; | |
ddbcc7e8 PM |
144 | }; |
145 | ||
ddbcc7e8 PM |
146 | /* |
147 | * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the | |
148 | * subsystems that are otherwise unattached - it never has more than a | |
149 | * single cgroup, and all tasks are part of that cgroup. | |
150 | */ | |
151 | static struct cgroupfs_root rootnode; | |
152 | ||
05ef1d7c TH |
153 | /* |
154 | * cgroupfs file entry, pointed to from leaf dentry->d_fsdata. | |
155 | */ | |
156 | struct cfent { | |
157 | struct list_head node; | |
158 | struct dentry *dentry; | |
159 | struct cftype *type; | |
160 | }; | |
161 | ||
38460b48 KH |
162 | /* |
163 | * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when | |
164 | * cgroup_subsys->use_id != 0. | |
165 | */ | |
166 | #define CSS_ID_MAX (65535) | |
167 | struct css_id { | |
168 | /* | |
169 | * The css to which this ID points. This pointer is set to valid value | |
170 | * after cgroup is populated. If cgroup is removed, this will be NULL. | |
171 | * This pointer is expected to be RCU-safe because destroy() | |
172 | * is called after synchronize_rcu(). But for safe use, css_is_removed() | |
173 | * css_tryget() should be used for avoiding race. | |
174 | */ | |
2c392b8c | 175 | struct cgroup_subsys_state __rcu *css; |
38460b48 KH |
176 | /* |
177 | * ID of this css. | |
178 | */ | |
179 | unsigned short id; | |
180 | /* | |
181 | * Depth in hierarchy which this ID belongs to. | |
182 | */ | |
183 | unsigned short depth; | |
184 | /* | |
185 | * ID is freed by RCU. (and lookup routine is RCU safe.) | |
186 | */ | |
187 | struct rcu_head rcu_head; | |
188 | /* | |
189 | * Hierarchy of CSS ID belongs to. | |
190 | */ | |
191 | unsigned short stack[0]; /* Array of Length (depth+1) */ | |
192 | }; | |
193 | ||
0dea1168 | 194 | /* |
25985edc | 195 | * cgroup_event represents events which userspace want to receive. |
0dea1168 KS |
196 | */ |
197 | struct cgroup_event { | |
198 | /* | |
199 | * Cgroup which the event belongs to. | |
200 | */ | |
201 | struct cgroup *cgrp; | |
202 | /* | |
203 | * Control file which the event associated. | |
204 | */ | |
205 | struct cftype *cft; | |
206 | /* | |
207 | * eventfd to signal userspace about the event. | |
208 | */ | |
209 | struct eventfd_ctx *eventfd; | |
210 | /* | |
211 | * Each of these stored in a list by the cgroup. | |
212 | */ | |
213 | struct list_head list; | |
214 | /* | |
215 | * All fields below needed to unregister event when | |
216 | * userspace closes eventfd. | |
217 | */ | |
218 | poll_table pt; | |
219 | wait_queue_head_t *wqh; | |
220 | wait_queue_t wait; | |
221 | struct work_struct remove; | |
222 | }; | |
38460b48 | 223 | |
ddbcc7e8 PM |
224 | /* The list of hierarchy roots */ |
225 | ||
226 | static LIST_HEAD(roots); | |
817929ec | 227 | static int root_count; |
ddbcc7e8 | 228 | |
2c6ab6d2 PM |
229 | static DEFINE_IDA(hierarchy_ida); |
230 | static int next_hierarchy_id; | |
231 | static DEFINE_SPINLOCK(hierarchy_id_lock); | |
232 | ||
ddbcc7e8 PM |
233 | /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ |
234 | #define dummytop (&rootnode.top_cgroup) | |
235 | ||
236 | /* This flag indicates whether tasks in the fork and exit paths should | |
a043e3b2 LZ |
237 | * check for fork/exit handlers to call. This avoids us having to do |
238 | * extra work in the fork/exit path if none of the subsystems need to | |
239 | * be called. | |
ddbcc7e8 | 240 | */ |
8947f9d5 | 241 | static int need_forkexit_callback __read_mostly; |
ddbcc7e8 | 242 | |
d11c563d PM |
243 | #ifdef CONFIG_PROVE_LOCKING |
244 | int cgroup_lock_is_held(void) | |
245 | { | |
246 | return lockdep_is_held(&cgroup_mutex); | |
247 | } | |
248 | #else /* #ifdef CONFIG_PROVE_LOCKING */ | |
249 | int cgroup_lock_is_held(void) | |
250 | { | |
251 | return mutex_is_locked(&cgroup_mutex); | |
252 | } | |
253 | #endif /* #else #ifdef CONFIG_PROVE_LOCKING */ | |
254 | ||
255 | EXPORT_SYMBOL_GPL(cgroup_lock_is_held); | |
256 | ||
28b4c27b TH |
257 | /* the current nr of refs, always >= 0 whether @css is deactivated or not */ |
258 | static int css_refcnt(struct cgroup_subsys_state *css) | |
259 | { | |
260 | int v = atomic_read(&css->refcnt); | |
261 | ||
262 | return v >= 0 ? v : v - CSS_DEACT_BIAS; | |
263 | } | |
264 | ||
ddbcc7e8 | 265 | /* convenient tests for these bits */ |
bd89aabc | 266 | inline int cgroup_is_removed(const struct cgroup *cgrp) |
ddbcc7e8 | 267 | { |
bd89aabc | 268 | return test_bit(CGRP_REMOVED, &cgrp->flags); |
ddbcc7e8 PM |
269 | } |
270 | ||
271 | /* bits in struct cgroupfs_root flags field */ | |
272 | enum { | |
273 | ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ | |
274 | }; | |
275 | ||
e9685a03 | 276 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
81a6a5cd PM |
277 | { |
278 | const int bits = | |
bd89aabc PM |
279 | (1 << CGRP_RELEASABLE) | |
280 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
281 | return (cgrp->flags & bits) == bits; | |
81a6a5cd PM |
282 | } |
283 | ||
e9685a03 | 284 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 285 | { |
bd89aabc | 286 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
287 | } |
288 | ||
97978e6d DL |
289 | static int clone_children(const struct cgroup *cgrp) |
290 | { | |
291 | return test_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
292 | } | |
293 | ||
ddbcc7e8 PM |
294 | /* |
295 | * for_each_subsys() allows you to iterate on each subsystem attached to | |
296 | * an active hierarchy | |
297 | */ | |
298 | #define for_each_subsys(_root, _ss) \ | |
299 | list_for_each_entry(_ss, &_root->subsys_list, sibling) | |
300 | ||
e5f6a860 LZ |
301 | /* for_each_active_root() allows you to iterate across the active hierarchies */ |
302 | #define for_each_active_root(_root) \ | |
ddbcc7e8 PM |
303 | list_for_each_entry(_root, &roots, root_list) |
304 | ||
f6ea9372 TH |
305 | static inline struct cgroup *__d_cgrp(struct dentry *dentry) |
306 | { | |
307 | return dentry->d_fsdata; | |
308 | } | |
309 | ||
05ef1d7c | 310 | static inline struct cfent *__d_cfe(struct dentry *dentry) |
f6ea9372 TH |
311 | { |
312 | return dentry->d_fsdata; | |
313 | } | |
314 | ||
05ef1d7c TH |
315 | static inline struct cftype *__d_cft(struct dentry *dentry) |
316 | { | |
317 | return __d_cfe(dentry)->type; | |
318 | } | |
319 | ||
81a6a5cd PM |
320 | /* the list of cgroups eligible for automatic release. Protected by |
321 | * release_list_lock */ | |
322 | static LIST_HEAD(release_list); | |
cdcc136f | 323 | static DEFINE_RAW_SPINLOCK(release_list_lock); |
81a6a5cd PM |
324 | static void cgroup_release_agent(struct work_struct *work); |
325 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
bd89aabc | 326 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 327 | |
817929ec PM |
328 | /* Link structure for associating css_set objects with cgroups */ |
329 | struct cg_cgroup_link { | |
330 | /* | |
331 | * List running through cg_cgroup_links associated with a | |
332 | * cgroup, anchored on cgroup->css_sets | |
333 | */ | |
bd89aabc | 334 | struct list_head cgrp_link_list; |
7717f7ba | 335 | struct cgroup *cgrp; |
817929ec PM |
336 | /* |
337 | * List running through cg_cgroup_links pointing at a | |
338 | * single css_set object, anchored on css_set->cg_links | |
339 | */ | |
340 | struct list_head cg_link_list; | |
341 | struct css_set *cg; | |
342 | }; | |
343 | ||
344 | /* The default css_set - used by init and its children prior to any | |
345 | * hierarchies being mounted. It contains a pointer to the root state | |
346 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
347 | * reference-counted, to improve performance when child cgroups | |
348 | * haven't been created. | |
349 | */ | |
350 | ||
351 | static struct css_set init_css_set; | |
352 | static struct cg_cgroup_link init_css_set_link; | |
353 | ||
e6a1105b BB |
354 | static int cgroup_init_idr(struct cgroup_subsys *ss, |
355 | struct cgroup_subsys_state *css); | |
38460b48 | 356 | |
817929ec PM |
357 | /* css_set_lock protects the list of css_set objects, and the |
358 | * chain of tasks off each css_set. Nests outside task->alloc_lock | |
359 | * due to cgroup_iter_start() */ | |
360 | static DEFINE_RWLOCK(css_set_lock); | |
361 | static int css_set_count; | |
362 | ||
7717f7ba PM |
363 | /* |
364 | * hash table for cgroup groups. This improves the performance to find | |
365 | * an existing css_set. This hash doesn't (currently) take into | |
366 | * account cgroups in empty hierarchies. | |
367 | */ | |
472b1053 LZ |
368 | #define CSS_SET_HASH_BITS 7 |
369 | #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS) | |
370 | static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE]; | |
371 | ||
372 | static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) | |
373 | { | |
374 | int i; | |
375 | int index; | |
376 | unsigned long tmp = 0UL; | |
377 | ||
378 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) | |
379 | tmp += (unsigned long)css[i]; | |
380 | tmp = (tmp >> 16) ^ tmp; | |
381 | ||
382 | index = hash_long(tmp, CSS_SET_HASH_BITS); | |
383 | ||
384 | return &css_set_table[index]; | |
385 | } | |
386 | ||
817929ec PM |
387 | /* We don't maintain the lists running through each css_set to its |
388 | * task until after the first call to cgroup_iter_start(). This | |
389 | * reduces the fork()/exit() overhead for people who have cgroups | |
390 | * compiled into their kernel but not actually in use */ | |
8947f9d5 | 391 | static int use_task_css_set_links __read_mostly; |
817929ec | 392 | |
2c6ab6d2 | 393 | static void __put_css_set(struct css_set *cg, int taskexit) |
b4f48b63 | 394 | { |
71cbb949 KM |
395 | struct cg_cgroup_link *link; |
396 | struct cg_cgroup_link *saved_link; | |
146aa1bd LJ |
397 | /* |
398 | * Ensure that the refcount doesn't hit zero while any readers | |
399 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
400 | * rwlock | |
401 | */ | |
402 | if (atomic_add_unless(&cg->refcount, -1, 1)) | |
403 | return; | |
404 | write_lock(&css_set_lock); | |
405 | if (!atomic_dec_and_test(&cg->refcount)) { | |
406 | write_unlock(&css_set_lock); | |
407 | return; | |
408 | } | |
81a6a5cd | 409 | |
2c6ab6d2 PM |
410 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
411 | hlist_del(&cg->hlist); | |
412 | css_set_count--; | |
413 | ||
414 | list_for_each_entry_safe(link, saved_link, &cg->cg_links, | |
415 | cg_link_list) { | |
416 | struct cgroup *cgrp = link->cgrp; | |
417 | list_del(&link->cg_link_list); | |
418 | list_del(&link->cgrp_link_list); | |
bd89aabc PM |
419 | if (atomic_dec_and_test(&cgrp->count) && |
420 | notify_on_release(cgrp)) { | |
81a6a5cd | 421 | if (taskexit) |
bd89aabc PM |
422 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
423 | check_for_release(cgrp); | |
81a6a5cd | 424 | } |
2c6ab6d2 PM |
425 | |
426 | kfree(link); | |
81a6a5cd | 427 | } |
2c6ab6d2 PM |
428 | |
429 | write_unlock(&css_set_lock); | |
30088ad8 | 430 | kfree_rcu(cg, rcu_head); |
b4f48b63 PM |
431 | } |
432 | ||
817929ec PM |
433 | /* |
434 | * refcounted get/put for css_set objects | |
435 | */ | |
436 | static inline void get_css_set(struct css_set *cg) | |
437 | { | |
146aa1bd | 438 | atomic_inc(&cg->refcount); |
817929ec PM |
439 | } |
440 | ||
441 | static inline void put_css_set(struct css_set *cg) | |
442 | { | |
146aa1bd | 443 | __put_css_set(cg, 0); |
817929ec PM |
444 | } |
445 | ||
81a6a5cd PM |
446 | static inline void put_css_set_taskexit(struct css_set *cg) |
447 | { | |
146aa1bd | 448 | __put_css_set(cg, 1); |
81a6a5cd PM |
449 | } |
450 | ||
7717f7ba PM |
451 | /* |
452 | * compare_css_sets - helper function for find_existing_css_set(). | |
453 | * @cg: candidate css_set being tested | |
454 | * @old_cg: existing css_set for a task | |
455 | * @new_cgrp: cgroup that's being entered by the task | |
456 | * @template: desired set of css pointers in css_set (pre-calculated) | |
457 | * | |
458 | * Returns true if "cg" matches "old_cg" except for the hierarchy | |
459 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". | |
460 | */ | |
461 | static bool compare_css_sets(struct css_set *cg, | |
462 | struct css_set *old_cg, | |
463 | struct cgroup *new_cgrp, | |
464 | struct cgroup_subsys_state *template[]) | |
465 | { | |
466 | struct list_head *l1, *l2; | |
467 | ||
468 | if (memcmp(template, cg->subsys, sizeof(cg->subsys))) { | |
469 | /* Not all subsystems matched */ | |
470 | return false; | |
471 | } | |
472 | ||
473 | /* | |
474 | * Compare cgroup pointers in order to distinguish between | |
475 | * different cgroups in heirarchies with no subsystems. We | |
476 | * could get by with just this check alone (and skip the | |
477 | * memcmp above) but on most setups the memcmp check will | |
478 | * avoid the need for this more expensive check on almost all | |
479 | * candidates. | |
480 | */ | |
481 | ||
482 | l1 = &cg->cg_links; | |
483 | l2 = &old_cg->cg_links; | |
484 | while (1) { | |
485 | struct cg_cgroup_link *cgl1, *cgl2; | |
486 | struct cgroup *cg1, *cg2; | |
487 | ||
488 | l1 = l1->next; | |
489 | l2 = l2->next; | |
490 | /* See if we reached the end - both lists are equal length. */ | |
491 | if (l1 == &cg->cg_links) { | |
492 | BUG_ON(l2 != &old_cg->cg_links); | |
493 | break; | |
494 | } else { | |
495 | BUG_ON(l2 == &old_cg->cg_links); | |
496 | } | |
497 | /* Locate the cgroups associated with these links. */ | |
498 | cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list); | |
499 | cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list); | |
500 | cg1 = cgl1->cgrp; | |
501 | cg2 = cgl2->cgrp; | |
502 | /* Hierarchies should be linked in the same order. */ | |
503 | BUG_ON(cg1->root != cg2->root); | |
504 | ||
505 | /* | |
506 | * If this hierarchy is the hierarchy of the cgroup | |
507 | * that's changing, then we need to check that this | |
508 | * css_set points to the new cgroup; if it's any other | |
509 | * hierarchy, then this css_set should point to the | |
510 | * same cgroup as the old css_set. | |
511 | */ | |
512 | if (cg1->root == new_cgrp->root) { | |
513 | if (cg1 != new_cgrp) | |
514 | return false; | |
515 | } else { | |
516 | if (cg1 != cg2) | |
517 | return false; | |
518 | } | |
519 | } | |
520 | return true; | |
521 | } | |
522 | ||
817929ec PM |
523 | /* |
524 | * find_existing_css_set() is a helper for | |
525 | * find_css_set(), and checks to see whether an existing | |
472b1053 | 526 | * css_set is suitable. |
817929ec PM |
527 | * |
528 | * oldcg: the cgroup group that we're using before the cgroup | |
529 | * transition | |
530 | * | |
bd89aabc | 531 | * cgrp: the cgroup that we're moving into |
817929ec PM |
532 | * |
533 | * template: location in which to build the desired set of subsystem | |
534 | * state objects for the new cgroup group | |
535 | */ | |
817929ec PM |
536 | static struct css_set *find_existing_css_set( |
537 | struct css_set *oldcg, | |
bd89aabc | 538 | struct cgroup *cgrp, |
817929ec | 539 | struct cgroup_subsys_state *template[]) |
b4f48b63 PM |
540 | { |
541 | int i; | |
bd89aabc | 542 | struct cgroupfs_root *root = cgrp->root; |
472b1053 LZ |
543 | struct hlist_head *hhead; |
544 | struct hlist_node *node; | |
545 | struct css_set *cg; | |
817929ec | 546 | |
aae8aab4 BB |
547 | /* |
548 | * Build the set of subsystem state objects that we want to see in the | |
549 | * new css_set. while subsystems can change globally, the entries here | |
550 | * won't change, so no need for locking. | |
551 | */ | |
817929ec | 552 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
8d53d55d | 553 | if (root->subsys_bits & (1UL << i)) { |
817929ec PM |
554 | /* Subsystem is in this hierarchy. So we want |
555 | * the subsystem state from the new | |
556 | * cgroup */ | |
bd89aabc | 557 | template[i] = cgrp->subsys[i]; |
817929ec PM |
558 | } else { |
559 | /* Subsystem is not in this hierarchy, so we | |
560 | * don't want to change the subsystem state */ | |
561 | template[i] = oldcg->subsys[i]; | |
562 | } | |
563 | } | |
564 | ||
472b1053 LZ |
565 | hhead = css_set_hash(template); |
566 | hlist_for_each_entry(cg, node, hhead, hlist) { | |
7717f7ba PM |
567 | if (!compare_css_sets(cg, oldcg, cgrp, template)) |
568 | continue; | |
569 | ||
570 | /* This css_set matches what we need */ | |
571 | return cg; | |
472b1053 | 572 | } |
817929ec PM |
573 | |
574 | /* No existing cgroup group matched */ | |
575 | return NULL; | |
576 | } | |
577 | ||
36553434 LZ |
578 | static void free_cg_links(struct list_head *tmp) |
579 | { | |
580 | struct cg_cgroup_link *link; | |
581 | struct cg_cgroup_link *saved_link; | |
582 | ||
583 | list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) { | |
584 | list_del(&link->cgrp_link_list); | |
585 | kfree(link); | |
586 | } | |
587 | } | |
588 | ||
817929ec PM |
589 | /* |
590 | * allocate_cg_links() allocates "count" cg_cgroup_link structures | |
bd89aabc | 591 | * and chains them on tmp through their cgrp_link_list fields. Returns 0 on |
817929ec PM |
592 | * success or a negative error |
593 | */ | |
817929ec PM |
594 | static int allocate_cg_links(int count, struct list_head *tmp) |
595 | { | |
596 | struct cg_cgroup_link *link; | |
597 | int i; | |
598 | INIT_LIST_HEAD(tmp); | |
599 | for (i = 0; i < count; i++) { | |
600 | link = kmalloc(sizeof(*link), GFP_KERNEL); | |
601 | if (!link) { | |
36553434 | 602 | free_cg_links(tmp); |
817929ec PM |
603 | return -ENOMEM; |
604 | } | |
bd89aabc | 605 | list_add(&link->cgrp_link_list, tmp); |
817929ec PM |
606 | } |
607 | return 0; | |
608 | } | |
609 | ||
c12f65d4 LZ |
610 | /** |
611 | * link_css_set - a helper function to link a css_set to a cgroup | |
612 | * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links() | |
613 | * @cg: the css_set to be linked | |
614 | * @cgrp: the destination cgroup | |
615 | */ | |
616 | static void link_css_set(struct list_head *tmp_cg_links, | |
617 | struct css_set *cg, struct cgroup *cgrp) | |
618 | { | |
619 | struct cg_cgroup_link *link; | |
620 | ||
621 | BUG_ON(list_empty(tmp_cg_links)); | |
622 | link = list_first_entry(tmp_cg_links, struct cg_cgroup_link, | |
623 | cgrp_link_list); | |
624 | link->cg = cg; | |
7717f7ba | 625 | link->cgrp = cgrp; |
2c6ab6d2 | 626 | atomic_inc(&cgrp->count); |
c12f65d4 | 627 | list_move(&link->cgrp_link_list, &cgrp->css_sets); |
7717f7ba PM |
628 | /* |
629 | * Always add links to the tail of the list so that the list | |
630 | * is sorted by order of hierarchy creation | |
631 | */ | |
632 | list_add_tail(&link->cg_link_list, &cg->cg_links); | |
c12f65d4 LZ |
633 | } |
634 | ||
817929ec PM |
635 | /* |
636 | * find_css_set() takes an existing cgroup group and a | |
637 | * cgroup object, and returns a css_set object that's | |
638 | * equivalent to the old group, but with the given cgroup | |
639 | * substituted into the appropriate hierarchy. Must be called with | |
640 | * cgroup_mutex held | |
641 | */ | |
817929ec | 642 | static struct css_set *find_css_set( |
bd89aabc | 643 | struct css_set *oldcg, struct cgroup *cgrp) |
817929ec PM |
644 | { |
645 | struct css_set *res; | |
646 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT]; | |
817929ec PM |
647 | |
648 | struct list_head tmp_cg_links; | |
817929ec | 649 | |
472b1053 | 650 | struct hlist_head *hhead; |
7717f7ba | 651 | struct cg_cgroup_link *link; |
472b1053 | 652 | |
817929ec PM |
653 | /* First see if we already have a cgroup group that matches |
654 | * the desired set */ | |
7e9abd89 | 655 | read_lock(&css_set_lock); |
bd89aabc | 656 | res = find_existing_css_set(oldcg, cgrp, template); |
817929ec PM |
657 | if (res) |
658 | get_css_set(res); | |
7e9abd89 | 659 | read_unlock(&css_set_lock); |
817929ec PM |
660 | |
661 | if (res) | |
662 | return res; | |
663 | ||
664 | res = kmalloc(sizeof(*res), GFP_KERNEL); | |
665 | if (!res) | |
666 | return NULL; | |
667 | ||
668 | /* Allocate all the cg_cgroup_link objects that we'll need */ | |
669 | if (allocate_cg_links(root_count, &tmp_cg_links) < 0) { | |
670 | kfree(res); | |
671 | return NULL; | |
672 | } | |
673 | ||
146aa1bd | 674 | atomic_set(&res->refcount, 1); |
817929ec PM |
675 | INIT_LIST_HEAD(&res->cg_links); |
676 | INIT_LIST_HEAD(&res->tasks); | |
472b1053 | 677 | INIT_HLIST_NODE(&res->hlist); |
817929ec PM |
678 | |
679 | /* Copy the set of subsystem state objects generated in | |
680 | * find_existing_css_set() */ | |
681 | memcpy(res->subsys, template, sizeof(res->subsys)); | |
682 | ||
683 | write_lock(&css_set_lock); | |
684 | /* Add reference counts and links from the new css_set. */ | |
7717f7ba PM |
685 | list_for_each_entry(link, &oldcg->cg_links, cg_link_list) { |
686 | struct cgroup *c = link->cgrp; | |
687 | if (c->root == cgrp->root) | |
688 | c = cgrp; | |
689 | link_css_set(&tmp_cg_links, res, c); | |
690 | } | |
817929ec PM |
691 | |
692 | BUG_ON(!list_empty(&tmp_cg_links)); | |
693 | ||
817929ec | 694 | css_set_count++; |
472b1053 LZ |
695 | |
696 | /* Add this cgroup group to the hash table */ | |
697 | hhead = css_set_hash(res->subsys); | |
698 | hlist_add_head(&res->hlist, hhead); | |
699 | ||
817929ec PM |
700 | write_unlock(&css_set_lock); |
701 | ||
702 | return res; | |
b4f48b63 PM |
703 | } |
704 | ||
7717f7ba PM |
705 | /* |
706 | * Return the cgroup for "task" from the given hierarchy. Must be | |
707 | * called with cgroup_mutex held. | |
708 | */ | |
709 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
710 | struct cgroupfs_root *root) | |
711 | { | |
712 | struct css_set *css; | |
713 | struct cgroup *res = NULL; | |
714 | ||
715 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); | |
716 | read_lock(&css_set_lock); | |
717 | /* | |
718 | * No need to lock the task - since we hold cgroup_mutex the | |
719 | * task can't change groups, so the only thing that can happen | |
720 | * is that it exits and its css is set back to init_css_set. | |
721 | */ | |
722 | css = task->cgroups; | |
723 | if (css == &init_css_set) { | |
724 | res = &root->top_cgroup; | |
725 | } else { | |
726 | struct cg_cgroup_link *link; | |
727 | list_for_each_entry(link, &css->cg_links, cg_link_list) { | |
728 | struct cgroup *c = link->cgrp; | |
729 | if (c->root == root) { | |
730 | res = c; | |
731 | break; | |
732 | } | |
733 | } | |
734 | } | |
735 | read_unlock(&css_set_lock); | |
736 | BUG_ON(!res); | |
737 | return res; | |
738 | } | |
739 | ||
ddbcc7e8 PM |
740 | /* |
741 | * There is one global cgroup mutex. We also require taking | |
742 | * task_lock() when dereferencing a task's cgroup subsys pointers. | |
743 | * See "The task_lock() exception", at the end of this comment. | |
744 | * | |
745 | * A task must hold cgroup_mutex to modify cgroups. | |
746 | * | |
747 | * Any task can increment and decrement the count field without lock. | |
748 | * So in general, code holding cgroup_mutex can't rely on the count | |
749 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 750 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
751 | * means that no tasks are currently attached, therefore there is no |
752 | * way a task attached to that cgroup can fork (the other way to | |
753 | * increment the count). So code holding cgroup_mutex can safely | |
754 | * assume that if the count is zero, it will stay zero. Similarly, if | |
755 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
756 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
757 | * needs that mutex. | |
758 | * | |
ddbcc7e8 PM |
759 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
760 | * (usually) take cgroup_mutex. These are the two most performance | |
761 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
762 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
763 | * is taken, and if the cgroup count is zero, a usermode call made | |
a043e3b2 LZ |
764 | * to the release agent with the name of the cgroup (path relative to |
765 | * the root of cgroup file system) as the argument. | |
ddbcc7e8 PM |
766 | * |
767 | * A cgroup can only be deleted if both its 'count' of using tasks | |
768 | * is zero, and its list of 'children' cgroups is empty. Since all | |
769 | * tasks in the system use _some_ cgroup, and since there is always at | |
770 | * least one task in the system (init, pid == 1), therefore, top_cgroup | |
771 | * always has either children cgroups and/or using tasks. So we don't | |
772 | * need a special hack to ensure that top_cgroup cannot be deleted. | |
773 | * | |
774 | * The task_lock() exception | |
775 | * | |
776 | * The need for this exception arises from the action of | |
956db3ca | 777 | * cgroup_attach_task(), which overwrites one tasks cgroup pointer with |
a043e3b2 | 778 | * another. It does so using cgroup_mutex, however there are |
ddbcc7e8 PM |
779 | * several performance critical places that need to reference |
780 | * task->cgroup without the expense of grabbing a system global | |
781 | * mutex. Therefore except as noted below, when dereferencing or, as | |
956db3ca | 782 | * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use |
ddbcc7e8 PM |
783 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in |
784 | * the task_struct routinely used for such matters. | |
785 | * | |
786 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 787 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
788 | */ |
789 | ||
ddbcc7e8 PM |
790 | /** |
791 | * cgroup_lock - lock out any changes to cgroup structures | |
792 | * | |
793 | */ | |
ddbcc7e8 PM |
794 | void cgroup_lock(void) |
795 | { | |
796 | mutex_lock(&cgroup_mutex); | |
797 | } | |
67523c48 | 798 | EXPORT_SYMBOL_GPL(cgroup_lock); |
ddbcc7e8 PM |
799 | |
800 | /** | |
801 | * cgroup_unlock - release lock on cgroup changes | |
802 | * | |
803 | * Undo the lock taken in a previous cgroup_lock() call. | |
804 | */ | |
ddbcc7e8 PM |
805 | void cgroup_unlock(void) |
806 | { | |
807 | mutex_unlock(&cgroup_mutex); | |
808 | } | |
67523c48 | 809 | EXPORT_SYMBOL_GPL(cgroup_unlock); |
ddbcc7e8 PM |
810 | |
811 | /* | |
812 | * A couple of forward declarations required, due to cyclic reference loop: | |
813 | * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> | |
814 | * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations | |
815 | * -> cgroup_mkdir. | |
816 | */ | |
817 | ||
18bb1db3 | 818 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode); |
c72a04e3 | 819 | static struct dentry *cgroup_lookup(struct inode *, struct dentry *, struct nameidata *); |
ddbcc7e8 | 820 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); |
bd89aabc | 821 | static int cgroup_populate_dir(struct cgroup *cgrp); |
6e1d5dcc | 822 | static const struct inode_operations cgroup_dir_inode_operations; |
828c0950 | 823 | static const struct file_operations proc_cgroupstats_operations; |
a424316c PM |
824 | |
825 | static struct backing_dev_info cgroup_backing_dev_info = { | |
d993831f | 826 | .name = "cgroup", |
e4ad08fe | 827 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
a424316c | 828 | }; |
ddbcc7e8 | 829 | |
38460b48 KH |
830 | static int alloc_css_id(struct cgroup_subsys *ss, |
831 | struct cgroup *parent, struct cgroup *child); | |
832 | ||
a5e7ed32 | 833 | static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) |
ddbcc7e8 PM |
834 | { |
835 | struct inode *inode = new_inode(sb); | |
ddbcc7e8 PM |
836 | |
837 | if (inode) { | |
85fe4025 | 838 | inode->i_ino = get_next_ino(); |
ddbcc7e8 | 839 | inode->i_mode = mode; |
76aac0e9 DH |
840 | inode->i_uid = current_fsuid(); |
841 | inode->i_gid = current_fsgid(); | |
ddbcc7e8 PM |
842 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
843 | inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; | |
844 | } | |
845 | return inode; | |
846 | } | |
847 | ||
4fca88c8 KH |
848 | /* |
849 | * Call subsys's pre_destroy handler. | |
850 | * This is called before css refcnt check. | |
851 | */ | |
ec64f515 | 852 | static int cgroup_call_pre_destroy(struct cgroup *cgrp) |
4fca88c8 KH |
853 | { |
854 | struct cgroup_subsys *ss; | |
ec64f515 KH |
855 | int ret = 0; |
856 | ||
48ddbe19 TH |
857 | for_each_subsys(cgrp->root, ss) { |
858 | if (!ss->pre_destroy) | |
859 | continue; | |
860 | ||
861 | ret = ss->pre_destroy(cgrp); | |
862 | if (ret) { | |
863 | /* ->pre_destroy() failure is being deprecated */ | |
864 | WARN_ON_ONCE(!ss->__DEPRECATED_clear_css_refs); | |
865 | break; | |
ec64f515 | 866 | } |
48ddbe19 | 867 | } |
0dea1168 | 868 | |
ec64f515 | 869 | return ret; |
4fca88c8 KH |
870 | } |
871 | ||
ddbcc7e8 PM |
872 | static void cgroup_diput(struct dentry *dentry, struct inode *inode) |
873 | { | |
874 | /* is dentry a directory ? if so, kfree() associated cgroup */ | |
875 | if (S_ISDIR(inode->i_mode)) { | |
bd89aabc | 876 | struct cgroup *cgrp = dentry->d_fsdata; |
8dc4f3e1 | 877 | struct cgroup_subsys *ss; |
bd89aabc | 878 | BUG_ON(!(cgroup_is_removed(cgrp))); |
81a6a5cd PM |
879 | /* It's possible for external users to be holding css |
880 | * reference counts on a cgroup; css_put() needs to | |
881 | * be able to access the cgroup after decrementing | |
882 | * the reference count in order to know if it needs to | |
883 | * queue the cgroup to be handled by the release | |
884 | * agent */ | |
885 | synchronize_rcu(); | |
8dc4f3e1 PM |
886 | |
887 | mutex_lock(&cgroup_mutex); | |
888 | /* | |
889 | * Release the subsystem state objects. | |
890 | */ | |
75139b82 | 891 | for_each_subsys(cgrp->root, ss) |
761b3ef5 | 892 | ss->destroy(cgrp); |
8dc4f3e1 PM |
893 | |
894 | cgrp->root->number_of_cgroups--; | |
895 | mutex_unlock(&cgroup_mutex); | |
896 | ||
a47295e6 PM |
897 | /* |
898 | * Drop the active superblock reference that we took when we | |
899 | * created the cgroup | |
900 | */ | |
8dc4f3e1 PM |
901 | deactivate_super(cgrp->root->sb); |
902 | ||
72a8cb30 BB |
903 | /* |
904 | * if we're getting rid of the cgroup, refcount should ensure | |
905 | * that there are no pidlists left. | |
906 | */ | |
907 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
908 | ||
f2da1c40 | 909 | kfree_rcu(cgrp, rcu_head); |
05ef1d7c TH |
910 | } else { |
911 | struct cfent *cfe = __d_cfe(dentry); | |
912 | struct cgroup *cgrp = dentry->d_parent->d_fsdata; | |
913 | ||
914 | WARN_ONCE(!list_empty(&cfe->node) && | |
915 | cgrp != &cgrp->root->top_cgroup, | |
916 | "cfe still linked for %s\n", cfe->type->name); | |
917 | kfree(cfe); | |
ddbcc7e8 PM |
918 | } |
919 | iput(inode); | |
920 | } | |
921 | ||
c72a04e3 AV |
922 | static int cgroup_delete(const struct dentry *d) |
923 | { | |
924 | return 1; | |
925 | } | |
926 | ||
ddbcc7e8 PM |
927 | static void remove_dir(struct dentry *d) |
928 | { | |
929 | struct dentry *parent = dget(d->d_parent); | |
930 | ||
931 | d_delete(d); | |
932 | simple_rmdir(parent->d_inode, d); | |
933 | dput(parent); | |
934 | } | |
935 | ||
05ef1d7c TH |
936 | static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
937 | { | |
938 | struct cfent *cfe; | |
939 | ||
940 | lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); | |
941 | lockdep_assert_held(&cgroup_mutex); | |
942 | ||
943 | list_for_each_entry(cfe, &cgrp->files, node) { | |
944 | struct dentry *d = cfe->dentry; | |
945 | ||
946 | if (cft && cfe->type != cft) | |
947 | continue; | |
948 | ||
949 | dget(d); | |
950 | d_delete(d); | |
951 | simple_unlink(d->d_inode, d); | |
952 | list_del_init(&cfe->node); | |
953 | dput(d); | |
954 | ||
955 | return 0; | |
ddbcc7e8 | 956 | } |
05ef1d7c TH |
957 | return -ENOENT; |
958 | } | |
959 | ||
960 | static void cgroup_clear_directory(struct dentry *dir) | |
961 | { | |
962 | struct cgroup *cgrp = __d_cgrp(dir); | |
963 | ||
964 | while (!list_empty(&cgrp->files)) | |
965 | cgroup_rm_file(cgrp, NULL); | |
ddbcc7e8 PM |
966 | } |
967 | ||
968 | /* | |
969 | * NOTE : the dentry must have been dget()'ed | |
970 | */ | |
971 | static void cgroup_d_remove_dir(struct dentry *dentry) | |
972 | { | |
2fd6b7f5 NP |
973 | struct dentry *parent; |
974 | ||
ddbcc7e8 PM |
975 | cgroup_clear_directory(dentry); |
976 | ||
2fd6b7f5 NP |
977 | parent = dentry->d_parent; |
978 | spin_lock(&parent->d_lock); | |
3ec762ad | 979 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
ddbcc7e8 | 980 | list_del_init(&dentry->d_u.d_child); |
2fd6b7f5 NP |
981 | spin_unlock(&dentry->d_lock); |
982 | spin_unlock(&parent->d_lock); | |
ddbcc7e8 PM |
983 | remove_dir(dentry); |
984 | } | |
985 | ||
ec64f515 KH |
986 | /* |
987 | * A queue for waiters to do rmdir() cgroup. A tasks will sleep when | |
988 | * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some | |
989 | * reference to css->refcnt. In general, this refcnt is expected to goes down | |
990 | * to zero, soon. | |
991 | * | |
88703267 | 992 | * CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex; |
ec64f515 | 993 | */ |
1c6c3fad | 994 | static DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq); |
ec64f515 | 995 | |
88703267 | 996 | static void cgroup_wakeup_rmdir_waiter(struct cgroup *cgrp) |
ec64f515 | 997 | { |
88703267 | 998 | if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags))) |
ec64f515 KH |
999 | wake_up_all(&cgroup_rmdir_waitq); |
1000 | } | |
1001 | ||
88703267 KH |
1002 | void cgroup_exclude_rmdir(struct cgroup_subsys_state *css) |
1003 | { | |
1004 | css_get(css); | |
1005 | } | |
1006 | ||
1007 | void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css) | |
1008 | { | |
1009 | cgroup_wakeup_rmdir_waiter(css->cgroup); | |
1010 | css_put(css); | |
1011 | } | |
1012 | ||
aae8aab4 | 1013 | /* |
cf5d5941 BB |
1014 | * Call with cgroup_mutex held. Drops reference counts on modules, including |
1015 | * any duplicate ones that parse_cgroupfs_options took. If this function | |
1016 | * returns an error, no reference counts are touched. | |
aae8aab4 | 1017 | */ |
ddbcc7e8 PM |
1018 | static int rebind_subsystems(struct cgroupfs_root *root, |
1019 | unsigned long final_bits) | |
1020 | { | |
1021 | unsigned long added_bits, removed_bits; | |
bd89aabc | 1022 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
1023 | int i; |
1024 | ||
aae8aab4 | 1025 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
e25e2cbb | 1026 | BUG_ON(!mutex_is_locked(&cgroup_root_mutex)); |
aae8aab4 | 1027 | |
ddbcc7e8 PM |
1028 | removed_bits = root->actual_subsys_bits & ~final_bits; |
1029 | added_bits = final_bits & ~root->actual_subsys_bits; | |
1030 | /* Check that any added subsystems are currently free */ | |
1031 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
8d53d55d | 1032 | unsigned long bit = 1UL << i; |
ddbcc7e8 PM |
1033 | struct cgroup_subsys *ss = subsys[i]; |
1034 | if (!(bit & added_bits)) | |
1035 | continue; | |
aae8aab4 BB |
1036 | /* |
1037 | * Nobody should tell us to do a subsys that doesn't exist: | |
1038 | * parse_cgroupfs_options should catch that case and refcounts | |
1039 | * ensure that subsystems won't disappear once selected. | |
1040 | */ | |
1041 | BUG_ON(ss == NULL); | |
ddbcc7e8 PM |
1042 | if (ss->root != &rootnode) { |
1043 | /* Subsystem isn't free */ | |
1044 | return -EBUSY; | |
1045 | } | |
1046 | } | |
1047 | ||
1048 | /* Currently we don't handle adding/removing subsystems when | |
1049 | * any child cgroups exist. This is theoretically supportable | |
1050 | * but involves complex error handling, so it's being left until | |
1051 | * later */ | |
307257cf | 1052 | if (root->number_of_cgroups > 1) |
ddbcc7e8 PM |
1053 | return -EBUSY; |
1054 | ||
1055 | /* Process each subsystem */ | |
1056 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1057 | struct cgroup_subsys *ss = subsys[i]; | |
1058 | unsigned long bit = 1UL << i; | |
1059 | if (bit & added_bits) { | |
1060 | /* We're binding this subsystem to this hierarchy */ | |
aae8aab4 | 1061 | BUG_ON(ss == NULL); |
bd89aabc | 1062 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
1063 | BUG_ON(!dummytop->subsys[i]); |
1064 | BUG_ON(dummytop->subsys[i]->cgroup != dummytop); | |
999cd8a4 | 1065 | mutex_lock(&ss->hierarchy_mutex); |
bd89aabc PM |
1066 | cgrp->subsys[i] = dummytop->subsys[i]; |
1067 | cgrp->subsys[i]->cgroup = cgrp; | |
33a68ac1 | 1068 | list_move(&ss->sibling, &root->subsys_list); |
b2aa30f7 | 1069 | ss->root = root; |
ddbcc7e8 | 1070 | if (ss->bind) |
761b3ef5 | 1071 | ss->bind(cgrp); |
999cd8a4 | 1072 | mutex_unlock(&ss->hierarchy_mutex); |
cf5d5941 | 1073 | /* refcount was already taken, and we're keeping it */ |
ddbcc7e8 PM |
1074 | } else if (bit & removed_bits) { |
1075 | /* We're removing this subsystem */ | |
aae8aab4 | 1076 | BUG_ON(ss == NULL); |
bd89aabc PM |
1077 | BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); |
1078 | BUG_ON(cgrp->subsys[i]->cgroup != cgrp); | |
999cd8a4 | 1079 | mutex_lock(&ss->hierarchy_mutex); |
ddbcc7e8 | 1080 | if (ss->bind) |
761b3ef5 | 1081 | ss->bind(dummytop); |
ddbcc7e8 | 1082 | dummytop->subsys[i]->cgroup = dummytop; |
bd89aabc | 1083 | cgrp->subsys[i] = NULL; |
b2aa30f7 | 1084 | subsys[i]->root = &rootnode; |
33a68ac1 | 1085 | list_move(&ss->sibling, &rootnode.subsys_list); |
999cd8a4 | 1086 | mutex_unlock(&ss->hierarchy_mutex); |
cf5d5941 BB |
1087 | /* subsystem is now free - drop reference on module */ |
1088 | module_put(ss->module); | |
ddbcc7e8 PM |
1089 | } else if (bit & final_bits) { |
1090 | /* Subsystem state should already exist */ | |
aae8aab4 | 1091 | BUG_ON(ss == NULL); |
bd89aabc | 1092 | BUG_ON(!cgrp->subsys[i]); |
cf5d5941 BB |
1093 | /* |
1094 | * a refcount was taken, but we already had one, so | |
1095 | * drop the extra reference. | |
1096 | */ | |
1097 | module_put(ss->module); | |
1098 | #ifdef CONFIG_MODULE_UNLOAD | |
1099 | BUG_ON(ss->module && !module_refcount(ss->module)); | |
1100 | #endif | |
ddbcc7e8 PM |
1101 | } else { |
1102 | /* Subsystem state shouldn't exist */ | |
bd89aabc | 1103 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
1104 | } |
1105 | } | |
1106 | root->subsys_bits = root->actual_subsys_bits = final_bits; | |
1107 | synchronize_rcu(); | |
1108 | ||
1109 | return 0; | |
1110 | } | |
1111 | ||
34c80b1d | 1112 | static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) |
ddbcc7e8 | 1113 | { |
34c80b1d | 1114 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; |
ddbcc7e8 PM |
1115 | struct cgroup_subsys *ss; |
1116 | ||
e25e2cbb | 1117 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1118 | for_each_subsys(root, ss) |
1119 | seq_printf(seq, ",%s", ss->name); | |
1120 | if (test_bit(ROOT_NOPREFIX, &root->flags)) | |
1121 | seq_puts(seq, ",noprefix"); | |
81a6a5cd PM |
1122 | if (strlen(root->release_agent_path)) |
1123 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
97978e6d DL |
1124 | if (clone_children(&root->top_cgroup)) |
1125 | seq_puts(seq, ",clone_children"); | |
c6d57f33 PM |
1126 | if (strlen(root->name)) |
1127 | seq_printf(seq, ",name=%s", root->name); | |
e25e2cbb | 1128 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1129 | return 0; |
1130 | } | |
1131 | ||
1132 | struct cgroup_sb_opts { | |
1133 | unsigned long subsys_bits; | |
1134 | unsigned long flags; | |
81a6a5cd | 1135 | char *release_agent; |
97978e6d | 1136 | bool clone_children; |
c6d57f33 | 1137 | char *name; |
2c6ab6d2 PM |
1138 | /* User explicitly requested empty subsystem */ |
1139 | bool none; | |
c6d57f33 PM |
1140 | |
1141 | struct cgroupfs_root *new_root; | |
2c6ab6d2 | 1142 | |
ddbcc7e8 PM |
1143 | }; |
1144 | ||
aae8aab4 BB |
1145 | /* |
1146 | * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call | |
cf5d5941 BB |
1147 | * with cgroup_mutex held to protect the subsys[] array. This function takes |
1148 | * refcounts on subsystems to be used, unless it returns error, in which case | |
1149 | * no refcounts are taken. | |
aae8aab4 | 1150 | */ |
cf5d5941 | 1151 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1152 | { |
32a8cf23 DL |
1153 | char *token, *o = data; |
1154 | bool all_ss = false, one_ss = false; | |
f9ab5b5b | 1155 | unsigned long mask = (unsigned long)-1; |
cf5d5941 BB |
1156 | int i; |
1157 | bool module_pin_failed = false; | |
f9ab5b5b | 1158 | |
aae8aab4 BB |
1159 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
1160 | ||
f9ab5b5b LZ |
1161 | #ifdef CONFIG_CPUSETS |
1162 | mask = ~(1UL << cpuset_subsys_id); | |
1163 | #endif | |
ddbcc7e8 | 1164 | |
c6d57f33 | 1165 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1166 | |
1167 | while ((token = strsep(&o, ",")) != NULL) { | |
1168 | if (!*token) | |
1169 | return -EINVAL; | |
32a8cf23 | 1170 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1171 | /* Explicitly have no subsystems */ |
1172 | opts->none = true; | |
32a8cf23 DL |
1173 | continue; |
1174 | } | |
1175 | if (!strcmp(token, "all")) { | |
1176 | /* Mutually exclusive option 'all' + subsystem name */ | |
1177 | if (one_ss) | |
1178 | return -EINVAL; | |
1179 | all_ss = true; | |
1180 | continue; | |
1181 | } | |
1182 | if (!strcmp(token, "noprefix")) { | |
ddbcc7e8 | 1183 | set_bit(ROOT_NOPREFIX, &opts->flags); |
32a8cf23 DL |
1184 | continue; |
1185 | } | |
1186 | if (!strcmp(token, "clone_children")) { | |
97978e6d | 1187 | opts->clone_children = true; |
32a8cf23 DL |
1188 | continue; |
1189 | } | |
1190 | if (!strncmp(token, "release_agent=", 14)) { | |
81a6a5cd PM |
1191 | /* Specifying two release agents is forbidden */ |
1192 | if (opts->release_agent) | |
1193 | return -EINVAL; | |
c6d57f33 | 1194 | opts->release_agent = |
e400c285 | 1195 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1196 | if (!opts->release_agent) |
1197 | return -ENOMEM; | |
32a8cf23 DL |
1198 | continue; |
1199 | } | |
1200 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1201 | const char *name = token + 5; |
1202 | /* Can't specify an empty name */ | |
1203 | if (!strlen(name)) | |
1204 | return -EINVAL; | |
1205 | /* Must match [\w.-]+ */ | |
1206 | for (i = 0; i < strlen(name); i++) { | |
1207 | char c = name[i]; | |
1208 | if (isalnum(c)) | |
1209 | continue; | |
1210 | if ((c == '.') || (c == '-') || (c == '_')) | |
1211 | continue; | |
1212 | return -EINVAL; | |
1213 | } | |
1214 | /* Specifying two names is forbidden */ | |
1215 | if (opts->name) | |
1216 | return -EINVAL; | |
1217 | opts->name = kstrndup(name, | |
e400c285 | 1218 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1219 | GFP_KERNEL); |
1220 | if (!opts->name) | |
1221 | return -ENOMEM; | |
32a8cf23 DL |
1222 | |
1223 | continue; | |
1224 | } | |
1225 | ||
1226 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1227 | struct cgroup_subsys *ss = subsys[i]; | |
1228 | if (ss == NULL) | |
1229 | continue; | |
1230 | if (strcmp(token, ss->name)) | |
1231 | continue; | |
1232 | if (ss->disabled) | |
1233 | continue; | |
1234 | ||
1235 | /* Mutually exclusive option 'all' + subsystem name */ | |
1236 | if (all_ss) | |
1237 | return -EINVAL; | |
1238 | set_bit(i, &opts->subsys_bits); | |
1239 | one_ss = true; | |
1240 | ||
1241 | break; | |
1242 | } | |
1243 | if (i == CGROUP_SUBSYS_COUNT) | |
1244 | return -ENOENT; | |
1245 | } | |
1246 | ||
1247 | /* | |
1248 | * If the 'all' option was specified select all the subsystems, | |
0d19ea86 LZ |
1249 | * otherwise if 'none', 'name=' and a subsystem name options |
1250 | * were not specified, let's default to 'all' | |
32a8cf23 | 1251 | */ |
0d19ea86 | 1252 | if (all_ss || (!one_ss && !opts->none && !opts->name)) { |
32a8cf23 DL |
1253 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
1254 | struct cgroup_subsys *ss = subsys[i]; | |
1255 | if (ss == NULL) | |
1256 | continue; | |
1257 | if (ss->disabled) | |
1258 | continue; | |
1259 | set_bit(i, &opts->subsys_bits); | |
ddbcc7e8 PM |
1260 | } |
1261 | } | |
1262 | ||
2c6ab6d2 PM |
1263 | /* Consistency checks */ |
1264 | ||
f9ab5b5b LZ |
1265 | /* |
1266 | * Option noprefix was introduced just for backward compatibility | |
1267 | * with the old cpuset, so we allow noprefix only if mounting just | |
1268 | * the cpuset subsystem. | |
1269 | */ | |
1270 | if (test_bit(ROOT_NOPREFIX, &opts->flags) && | |
1271 | (opts->subsys_bits & mask)) | |
1272 | return -EINVAL; | |
1273 | ||
2c6ab6d2 PM |
1274 | |
1275 | /* Can't specify "none" and some subsystems */ | |
1276 | if (opts->subsys_bits && opts->none) | |
1277 | return -EINVAL; | |
1278 | ||
1279 | /* | |
1280 | * We either have to specify by name or by subsystems. (So all | |
1281 | * empty hierarchies must have a name). | |
1282 | */ | |
c6d57f33 | 1283 | if (!opts->subsys_bits && !opts->name) |
ddbcc7e8 PM |
1284 | return -EINVAL; |
1285 | ||
cf5d5941 BB |
1286 | /* |
1287 | * Grab references on all the modules we'll need, so the subsystems | |
1288 | * don't dance around before rebind_subsystems attaches them. This may | |
1289 | * take duplicate reference counts on a subsystem that's already used, | |
1290 | * but rebind_subsystems handles this case. | |
1291 | */ | |
1292 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { | |
1293 | unsigned long bit = 1UL << i; | |
1294 | ||
1295 | if (!(bit & opts->subsys_bits)) | |
1296 | continue; | |
1297 | if (!try_module_get(subsys[i]->module)) { | |
1298 | module_pin_failed = true; | |
1299 | break; | |
1300 | } | |
1301 | } | |
1302 | if (module_pin_failed) { | |
1303 | /* | |
1304 | * oops, one of the modules was going away. this means that we | |
1305 | * raced with a module_delete call, and to the user this is | |
1306 | * essentially a "subsystem doesn't exist" case. | |
1307 | */ | |
1308 | for (i--; i >= CGROUP_BUILTIN_SUBSYS_COUNT; i--) { | |
1309 | /* drop refcounts only on the ones we took */ | |
1310 | unsigned long bit = 1UL << i; | |
1311 | ||
1312 | if (!(bit & opts->subsys_bits)) | |
1313 | continue; | |
1314 | module_put(subsys[i]->module); | |
1315 | } | |
1316 | return -ENOENT; | |
1317 | } | |
1318 | ||
ddbcc7e8 PM |
1319 | return 0; |
1320 | } | |
1321 | ||
cf5d5941 BB |
1322 | static void drop_parsed_module_refcounts(unsigned long subsys_bits) |
1323 | { | |
1324 | int i; | |
1325 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { | |
1326 | unsigned long bit = 1UL << i; | |
1327 | ||
1328 | if (!(bit & subsys_bits)) | |
1329 | continue; | |
1330 | module_put(subsys[i]->module); | |
1331 | } | |
1332 | } | |
1333 | ||
ddbcc7e8 PM |
1334 | static int cgroup_remount(struct super_block *sb, int *flags, char *data) |
1335 | { | |
1336 | int ret = 0; | |
1337 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1338 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
1339 | struct cgroup_sb_opts opts; |
1340 | ||
bd89aabc | 1341 | mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 | 1342 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1343 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1344 | |
1345 | /* See what subsystems are wanted */ | |
1346 | ret = parse_cgroupfs_options(data, &opts); | |
1347 | if (ret) | |
1348 | goto out_unlock; | |
1349 | ||
8b5a5a9d TH |
1350 | /* See feature-removal-schedule.txt */ |
1351 | if (opts.subsys_bits != root->actual_subsys_bits || opts.release_agent) | |
1352 | pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", | |
1353 | task_tgid_nr(current), current->comm); | |
1354 | ||
cf5d5941 BB |
1355 | /* Don't allow flags or name to change at remount */ |
1356 | if (opts.flags != root->flags || | |
1357 | (opts.name && strcmp(opts.name, root->name))) { | |
c6d57f33 | 1358 | ret = -EINVAL; |
cf5d5941 | 1359 | drop_parsed_module_refcounts(opts.subsys_bits); |
c6d57f33 PM |
1360 | goto out_unlock; |
1361 | } | |
1362 | ||
ddbcc7e8 | 1363 | ret = rebind_subsystems(root, opts.subsys_bits); |
cf5d5941 BB |
1364 | if (ret) { |
1365 | drop_parsed_module_refcounts(opts.subsys_bits); | |
0670e08b | 1366 | goto out_unlock; |
cf5d5941 | 1367 | } |
ddbcc7e8 | 1368 | |
ff4c8d50 TH |
1369 | /* clear out any existing files and repopulate subsystem files */ |
1370 | cgroup_clear_directory(cgrp->dentry); | |
0670e08b | 1371 | cgroup_populate_dir(cgrp); |
ddbcc7e8 | 1372 | |
81a6a5cd PM |
1373 | if (opts.release_agent) |
1374 | strcpy(root->release_agent_path, opts.release_agent); | |
ddbcc7e8 | 1375 | out_unlock: |
66bdc9cf | 1376 | kfree(opts.release_agent); |
c6d57f33 | 1377 | kfree(opts.name); |
e25e2cbb | 1378 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1379 | mutex_unlock(&cgroup_mutex); |
bd89aabc | 1380 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
1381 | return ret; |
1382 | } | |
1383 | ||
b87221de | 1384 | static const struct super_operations cgroup_ops = { |
ddbcc7e8 PM |
1385 | .statfs = simple_statfs, |
1386 | .drop_inode = generic_delete_inode, | |
1387 | .show_options = cgroup_show_options, | |
1388 | .remount_fs = cgroup_remount, | |
1389 | }; | |
1390 | ||
cc31edce PM |
1391 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1392 | { | |
1393 | INIT_LIST_HEAD(&cgrp->sibling); | |
1394 | INIT_LIST_HEAD(&cgrp->children); | |
05ef1d7c | 1395 | INIT_LIST_HEAD(&cgrp->files); |
cc31edce PM |
1396 | INIT_LIST_HEAD(&cgrp->css_sets); |
1397 | INIT_LIST_HEAD(&cgrp->release_list); | |
72a8cb30 BB |
1398 | INIT_LIST_HEAD(&cgrp->pidlists); |
1399 | mutex_init(&cgrp->pidlist_mutex); | |
0dea1168 KS |
1400 | INIT_LIST_HEAD(&cgrp->event_list); |
1401 | spin_lock_init(&cgrp->event_list_lock); | |
cc31edce | 1402 | } |
c6d57f33 | 1403 | |
ddbcc7e8 PM |
1404 | static void init_cgroup_root(struct cgroupfs_root *root) |
1405 | { | |
bd89aabc | 1406 | struct cgroup *cgrp = &root->top_cgroup; |
b0ca5a84 | 1407 | |
ddbcc7e8 PM |
1408 | INIT_LIST_HEAD(&root->subsys_list); |
1409 | INIT_LIST_HEAD(&root->root_list); | |
b0ca5a84 | 1410 | INIT_LIST_HEAD(&root->allcg_list); |
ddbcc7e8 | 1411 | root->number_of_cgroups = 1; |
bd89aabc PM |
1412 | cgrp->root = root; |
1413 | cgrp->top_cgroup = cgrp; | |
b0ca5a84 | 1414 | list_add_tail(&cgrp->allcg_node, &root->allcg_list); |
cc31edce | 1415 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 PM |
1416 | } |
1417 | ||
2c6ab6d2 PM |
1418 | static bool init_root_id(struct cgroupfs_root *root) |
1419 | { | |
1420 | int ret = 0; | |
1421 | ||
1422 | do { | |
1423 | if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL)) | |
1424 | return false; | |
1425 | spin_lock(&hierarchy_id_lock); | |
1426 | /* Try to allocate the next unused ID */ | |
1427 | ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id, | |
1428 | &root->hierarchy_id); | |
1429 | if (ret == -ENOSPC) | |
1430 | /* Try again starting from 0 */ | |
1431 | ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id); | |
1432 | if (!ret) { | |
1433 | next_hierarchy_id = root->hierarchy_id + 1; | |
1434 | } else if (ret != -EAGAIN) { | |
1435 | /* Can only get here if the 31-bit IDR is full ... */ | |
1436 | BUG_ON(ret); | |
1437 | } | |
1438 | spin_unlock(&hierarchy_id_lock); | |
1439 | } while (ret); | |
1440 | return true; | |
1441 | } | |
1442 | ||
ddbcc7e8 PM |
1443 | static int cgroup_test_super(struct super_block *sb, void *data) |
1444 | { | |
c6d57f33 | 1445 | struct cgroup_sb_opts *opts = data; |
ddbcc7e8 PM |
1446 | struct cgroupfs_root *root = sb->s_fs_info; |
1447 | ||
c6d57f33 PM |
1448 | /* If we asked for a name then it must match */ |
1449 | if (opts->name && strcmp(opts->name, root->name)) | |
1450 | return 0; | |
ddbcc7e8 | 1451 | |
2c6ab6d2 PM |
1452 | /* |
1453 | * If we asked for subsystems (or explicitly for no | |
1454 | * subsystems) then they must match | |
1455 | */ | |
1456 | if ((opts->subsys_bits || opts->none) | |
1457 | && (opts->subsys_bits != root->subsys_bits)) | |
ddbcc7e8 PM |
1458 | return 0; |
1459 | ||
1460 | return 1; | |
1461 | } | |
1462 | ||
c6d57f33 PM |
1463 | static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) |
1464 | { | |
1465 | struct cgroupfs_root *root; | |
1466 | ||
2c6ab6d2 | 1467 | if (!opts->subsys_bits && !opts->none) |
c6d57f33 PM |
1468 | return NULL; |
1469 | ||
1470 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
1471 | if (!root) | |
1472 | return ERR_PTR(-ENOMEM); | |
1473 | ||
2c6ab6d2 PM |
1474 | if (!init_root_id(root)) { |
1475 | kfree(root); | |
1476 | return ERR_PTR(-ENOMEM); | |
1477 | } | |
c6d57f33 | 1478 | init_cgroup_root(root); |
2c6ab6d2 | 1479 | |
c6d57f33 PM |
1480 | root->subsys_bits = opts->subsys_bits; |
1481 | root->flags = opts->flags; | |
1482 | if (opts->release_agent) | |
1483 | strcpy(root->release_agent_path, opts->release_agent); | |
1484 | if (opts->name) | |
1485 | strcpy(root->name, opts->name); | |
97978e6d DL |
1486 | if (opts->clone_children) |
1487 | set_bit(CGRP_CLONE_CHILDREN, &root->top_cgroup.flags); | |
c6d57f33 PM |
1488 | return root; |
1489 | } | |
1490 | ||
2c6ab6d2 PM |
1491 | static void cgroup_drop_root(struct cgroupfs_root *root) |
1492 | { | |
1493 | if (!root) | |
1494 | return; | |
1495 | ||
1496 | BUG_ON(!root->hierarchy_id); | |
1497 | spin_lock(&hierarchy_id_lock); | |
1498 | ida_remove(&hierarchy_ida, root->hierarchy_id); | |
1499 | spin_unlock(&hierarchy_id_lock); | |
1500 | kfree(root); | |
1501 | } | |
1502 | ||
ddbcc7e8 PM |
1503 | static int cgroup_set_super(struct super_block *sb, void *data) |
1504 | { | |
1505 | int ret; | |
c6d57f33 PM |
1506 | struct cgroup_sb_opts *opts = data; |
1507 | ||
1508 | /* If we don't have a new root, we can't set up a new sb */ | |
1509 | if (!opts->new_root) | |
1510 | return -EINVAL; | |
1511 | ||
2c6ab6d2 | 1512 | BUG_ON(!opts->subsys_bits && !opts->none); |
ddbcc7e8 PM |
1513 | |
1514 | ret = set_anon_super(sb, NULL); | |
1515 | if (ret) | |
1516 | return ret; | |
1517 | ||
c6d57f33 PM |
1518 | sb->s_fs_info = opts->new_root; |
1519 | opts->new_root->sb = sb; | |
ddbcc7e8 PM |
1520 | |
1521 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
1522 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
1523 | sb->s_magic = CGROUP_SUPER_MAGIC; | |
1524 | sb->s_op = &cgroup_ops; | |
1525 | ||
1526 | return 0; | |
1527 | } | |
1528 | ||
1529 | static int cgroup_get_rootdir(struct super_block *sb) | |
1530 | { | |
0df6a63f AV |
1531 | static const struct dentry_operations cgroup_dops = { |
1532 | .d_iput = cgroup_diput, | |
c72a04e3 | 1533 | .d_delete = cgroup_delete, |
0df6a63f AV |
1534 | }; |
1535 | ||
ddbcc7e8 PM |
1536 | struct inode *inode = |
1537 | cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); | |
ddbcc7e8 PM |
1538 | |
1539 | if (!inode) | |
1540 | return -ENOMEM; | |
1541 | ||
ddbcc7e8 PM |
1542 | inode->i_fop = &simple_dir_operations; |
1543 | inode->i_op = &cgroup_dir_inode_operations; | |
1544 | /* directories start off with i_nlink == 2 (for "." entry) */ | |
1545 | inc_nlink(inode); | |
48fde701 AV |
1546 | sb->s_root = d_make_root(inode); |
1547 | if (!sb->s_root) | |
ddbcc7e8 | 1548 | return -ENOMEM; |
0df6a63f AV |
1549 | /* for everything else we want ->d_op set */ |
1550 | sb->s_d_op = &cgroup_dops; | |
ddbcc7e8 PM |
1551 | return 0; |
1552 | } | |
1553 | ||
f7e83571 | 1554 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1555 | int flags, const char *unused_dev_name, |
f7e83571 | 1556 | void *data) |
ddbcc7e8 PM |
1557 | { |
1558 | struct cgroup_sb_opts opts; | |
c6d57f33 | 1559 | struct cgroupfs_root *root; |
ddbcc7e8 PM |
1560 | int ret = 0; |
1561 | struct super_block *sb; | |
c6d57f33 | 1562 | struct cgroupfs_root *new_root; |
e25e2cbb | 1563 | struct inode *inode; |
ddbcc7e8 PM |
1564 | |
1565 | /* First find the desired set of subsystems */ | |
aae8aab4 | 1566 | mutex_lock(&cgroup_mutex); |
ddbcc7e8 | 1567 | ret = parse_cgroupfs_options(data, &opts); |
aae8aab4 | 1568 | mutex_unlock(&cgroup_mutex); |
c6d57f33 PM |
1569 | if (ret) |
1570 | goto out_err; | |
ddbcc7e8 | 1571 | |
c6d57f33 PM |
1572 | /* |
1573 | * Allocate a new cgroup root. We may not need it if we're | |
1574 | * reusing an existing hierarchy. | |
1575 | */ | |
1576 | new_root = cgroup_root_from_opts(&opts); | |
1577 | if (IS_ERR(new_root)) { | |
1578 | ret = PTR_ERR(new_root); | |
cf5d5941 | 1579 | goto drop_modules; |
81a6a5cd | 1580 | } |
c6d57f33 | 1581 | opts.new_root = new_root; |
ddbcc7e8 | 1582 | |
c6d57f33 PM |
1583 | /* Locate an existing or new sb for this hierarchy */ |
1584 | sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts); | |
ddbcc7e8 | 1585 | if (IS_ERR(sb)) { |
c6d57f33 | 1586 | ret = PTR_ERR(sb); |
2c6ab6d2 | 1587 | cgroup_drop_root(opts.new_root); |
cf5d5941 | 1588 | goto drop_modules; |
ddbcc7e8 PM |
1589 | } |
1590 | ||
c6d57f33 PM |
1591 | root = sb->s_fs_info; |
1592 | BUG_ON(!root); | |
1593 | if (root == opts.new_root) { | |
1594 | /* We used the new root structure, so this is a new hierarchy */ | |
1595 | struct list_head tmp_cg_links; | |
c12f65d4 | 1596 | struct cgroup *root_cgrp = &root->top_cgroup; |
c6d57f33 | 1597 | struct cgroupfs_root *existing_root; |
2ce9738b | 1598 | const struct cred *cred; |
28fd5dfc | 1599 | int i; |
ddbcc7e8 PM |
1600 | |
1601 | BUG_ON(sb->s_root != NULL); | |
1602 | ||
1603 | ret = cgroup_get_rootdir(sb); | |
1604 | if (ret) | |
1605 | goto drop_new_super; | |
817929ec | 1606 | inode = sb->s_root->d_inode; |
ddbcc7e8 | 1607 | |
817929ec | 1608 | mutex_lock(&inode->i_mutex); |
ddbcc7e8 | 1609 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1610 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 | 1611 | |
e25e2cbb TH |
1612 | /* Check for name clashes with existing mounts */ |
1613 | ret = -EBUSY; | |
1614 | if (strlen(root->name)) | |
1615 | for_each_active_root(existing_root) | |
1616 | if (!strcmp(existing_root->name, root->name)) | |
1617 | goto unlock_drop; | |
c6d57f33 | 1618 | |
817929ec PM |
1619 | /* |
1620 | * We're accessing css_set_count without locking | |
1621 | * css_set_lock here, but that's OK - it can only be | |
1622 | * increased by someone holding cgroup_lock, and | |
1623 | * that's us. The worst that can happen is that we | |
1624 | * have some link structures left over | |
1625 | */ | |
1626 | ret = allocate_cg_links(css_set_count, &tmp_cg_links); | |
e25e2cbb TH |
1627 | if (ret) |
1628 | goto unlock_drop; | |
817929ec | 1629 | |
ddbcc7e8 PM |
1630 | ret = rebind_subsystems(root, root->subsys_bits); |
1631 | if (ret == -EBUSY) { | |
c6d57f33 | 1632 | free_cg_links(&tmp_cg_links); |
e25e2cbb | 1633 | goto unlock_drop; |
ddbcc7e8 | 1634 | } |
cf5d5941 BB |
1635 | /* |
1636 | * There must be no failure case after here, since rebinding | |
1637 | * takes care of subsystems' refcounts, which are explicitly | |
1638 | * dropped in the failure exit path. | |
1639 | */ | |
ddbcc7e8 PM |
1640 | |
1641 | /* EBUSY should be the only error here */ | |
1642 | BUG_ON(ret); | |
1643 | ||
1644 | list_add(&root->root_list, &roots); | |
817929ec | 1645 | root_count++; |
ddbcc7e8 | 1646 | |
c12f65d4 | 1647 | sb->s_root->d_fsdata = root_cgrp; |
ddbcc7e8 PM |
1648 | root->top_cgroup.dentry = sb->s_root; |
1649 | ||
817929ec PM |
1650 | /* Link the top cgroup in this hierarchy into all |
1651 | * the css_set objects */ | |
1652 | write_lock(&css_set_lock); | |
28fd5dfc LZ |
1653 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { |
1654 | struct hlist_head *hhead = &css_set_table[i]; | |
1655 | struct hlist_node *node; | |
817929ec | 1656 | struct css_set *cg; |
28fd5dfc | 1657 | |
c12f65d4 LZ |
1658 | hlist_for_each_entry(cg, node, hhead, hlist) |
1659 | link_css_set(&tmp_cg_links, cg, root_cgrp); | |
28fd5dfc | 1660 | } |
817929ec PM |
1661 | write_unlock(&css_set_lock); |
1662 | ||
1663 | free_cg_links(&tmp_cg_links); | |
1664 | ||
c12f65d4 LZ |
1665 | BUG_ON(!list_empty(&root_cgrp->sibling)); |
1666 | BUG_ON(!list_empty(&root_cgrp->children)); | |
ddbcc7e8 PM |
1667 | BUG_ON(root->number_of_cgroups != 1); |
1668 | ||
2ce9738b | 1669 | cred = override_creds(&init_cred); |
c12f65d4 | 1670 | cgroup_populate_dir(root_cgrp); |
2ce9738b | 1671 | revert_creds(cred); |
e25e2cbb | 1672 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1673 | mutex_unlock(&cgroup_mutex); |
34f77a90 | 1674 | mutex_unlock(&inode->i_mutex); |
c6d57f33 PM |
1675 | } else { |
1676 | /* | |
1677 | * We re-used an existing hierarchy - the new root (if | |
1678 | * any) is not needed | |
1679 | */ | |
2c6ab6d2 | 1680 | cgroup_drop_root(opts.new_root); |
cf5d5941 BB |
1681 | /* no subsys rebinding, so refcounts don't change */ |
1682 | drop_parsed_module_refcounts(opts.subsys_bits); | |
ddbcc7e8 PM |
1683 | } |
1684 | ||
c6d57f33 PM |
1685 | kfree(opts.release_agent); |
1686 | kfree(opts.name); | |
f7e83571 | 1687 | return dget(sb->s_root); |
ddbcc7e8 | 1688 | |
e25e2cbb TH |
1689 | unlock_drop: |
1690 | mutex_unlock(&cgroup_root_mutex); | |
1691 | mutex_unlock(&cgroup_mutex); | |
1692 | mutex_unlock(&inode->i_mutex); | |
ddbcc7e8 | 1693 | drop_new_super: |
6f5bbff9 | 1694 | deactivate_locked_super(sb); |
cf5d5941 BB |
1695 | drop_modules: |
1696 | drop_parsed_module_refcounts(opts.subsys_bits); | |
c6d57f33 PM |
1697 | out_err: |
1698 | kfree(opts.release_agent); | |
1699 | kfree(opts.name); | |
f7e83571 | 1700 | return ERR_PTR(ret); |
ddbcc7e8 PM |
1701 | } |
1702 | ||
1703 | static void cgroup_kill_sb(struct super_block *sb) { | |
1704 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1705 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 | 1706 | int ret; |
71cbb949 KM |
1707 | struct cg_cgroup_link *link; |
1708 | struct cg_cgroup_link *saved_link; | |
ddbcc7e8 PM |
1709 | |
1710 | BUG_ON(!root); | |
1711 | ||
1712 | BUG_ON(root->number_of_cgroups != 1); | |
bd89aabc PM |
1713 | BUG_ON(!list_empty(&cgrp->children)); |
1714 | BUG_ON(!list_empty(&cgrp->sibling)); | |
ddbcc7e8 PM |
1715 | |
1716 | mutex_lock(&cgroup_mutex); | |
e25e2cbb | 1717 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1718 | |
1719 | /* Rebind all subsystems back to the default hierarchy */ | |
1720 | ret = rebind_subsystems(root, 0); | |
1721 | /* Shouldn't be able to fail ... */ | |
1722 | BUG_ON(ret); | |
1723 | ||
817929ec PM |
1724 | /* |
1725 | * Release all the links from css_sets to this hierarchy's | |
1726 | * root cgroup | |
1727 | */ | |
1728 | write_lock(&css_set_lock); | |
71cbb949 KM |
1729 | |
1730 | list_for_each_entry_safe(link, saved_link, &cgrp->css_sets, | |
1731 | cgrp_link_list) { | |
817929ec | 1732 | list_del(&link->cg_link_list); |
bd89aabc | 1733 | list_del(&link->cgrp_link_list); |
817929ec PM |
1734 | kfree(link); |
1735 | } | |
1736 | write_unlock(&css_set_lock); | |
1737 | ||
839ec545 PM |
1738 | if (!list_empty(&root->root_list)) { |
1739 | list_del(&root->root_list); | |
1740 | root_count--; | |
1741 | } | |
e5f6a860 | 1742 | |
e25e2cbb | 1743 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1744 | mutex_unlock(&cgroup_mutex); |
1745 | ||
ddbcc7e8 | 1746 | kill_litter_super(sb); |
2c6ab6d2 | 1747 | cgroup_drop_root(root); |
ddbcc7e8 PM |
1748 | } |
1749 | ||
1750 | static struct file_system_type cgroup_fs_type = { | |
1751 | .name = "cgroup", | |
f7e83571 | 1752 | .mount = cgroup_mount, |
ddbcc7e8 PM |
1753 | .kill_sb = cgroup_kill_sb, |
1754 | }; | |
1755 | ||
676db4af GKH |
1756 | static struct kobject *cgroup_kobj; |
1757 | ||
a043e3b2 LZ |
1758 | /** |
1759 | * cgroup_path - generate the path of a cgroup | |
1760 | * @cgrp: the cgroup in question | |
1761 | * @buf: the buffer to write the path into | |
1762 | * @buflen: the length of the buffer | |
1763 | * | |
a47295e6 PM |
1764 | * Called with cgroup_mutex held or else with an RCU-protected cgroup |
1765 | * reference. Writes path of cgroup into buf. Returns 0 on success, | |
1766 | * -errno on error. | |
ddbcc7e8 | 1767 | */ |
bd89aabc | 1768 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) |
ddbcc7e8 PM |
1769 | { |
1770 | char *start; | |
9a9686b6 | 1771 | struct dentry *dentry = rcu_dereference_check(cgrp->dentry, |
9a9686b6 | 1772 | cgroup_lock_is_held()); |
ddbcc7e8 | 1773 | |
a47295e6 | 1774 | if (!dentry || cgrp == dummytop) { |
ddbcc7e8 PM |
1775 | /* |
1776 | * Inactive subsystems have no dentry for their root | |
1777 | * cgroup | |
1778 | */ | |
1779 | strcpy(buf, "/"); | |
1780 | return 0; | |
1781 | } | |
1782 | ||
1783 | start = buf + buflen; | |
1784 | ||
1785 | *--start = '\0'; | |
1786 | for (;;) { | |
a47295e6 | 1787 | int len = dentry->d_name.len; |
9a9686b6 | 1788 | |
ddbcc7e8 PM |
1789 | if ((start -= len) < buf) |
1790 | return -ENAMETOOLONG; | |
9a9686b6 | 1791 | memcpy(start, dentry->d_name.name, len); |
bd89aabc PM |
1792 | cgrp = cgrp->parent; |
1793 | if (!cgrp) | |
ddbcc7e8 | 1794 | break; |
9a9686b6 LZ |
1795 | |
1796 | dentry = rcu_dereference_check(cgrp->dentry, | |
9a9686b6 | 1797 | cgroup_lock_is_held()); |
bd89aabc | 1798 | if (!cgrp->parent) |
ddbcc7e8 PM |
1799 | continue; |
1800 | if (--start < buf) | |
1801 | return -ENAMETOOLONG; | |
1802 | *start = '/'; | |
1803 | } | |
1804 | memmove(buf, start, buf + buflen - start); | |
1805 | return 0; | |
1806 | } | |
67523c48 | 1807 | EXPORT_SYMBOL_GPL(cgroup_path); |
ddbcc7e8 | 1808 | |
2f7ee569 TH |
1809 | /* |
1810 | * Control Group taskset | |
1811 | */ | |
134d3373 TH |
1812 | struct task_and_cgroup { |
1813 | struct task_struct *task; | |
1814 | struct cgroup *cgrp; | |
61d1d219 | 1815 | struct css_set *cg; |
134d3373 TH |
1816 | }; |
1817 | ||
2f7ee569 TH |
1818 | struct cgroup_taskset { |
1819 | struct task_and_cgroup single; | |
1820 | struct flex_array *tc_array; | |
1821 | int tc_array_len; | |
1822 | int idx; | |
1823 | struct cgroup *cur_cgrp; | |
1824 | }; | |
1825 | ||
1826 | /** | |
1827 | * cgroup_taskset_first - reset taskset and return the first task | |
1828 | * @tset: taskset of interest | |
1829 | * | |
1830 | * @tset iteration is initialized and the first task is returned. | |
1831 | */ | |
1832 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
1833 | { | |
1834 | if (tset->tc_array) { | |
1835 | tset->idx = 0; | |
1836 | return cgroup_taskset_next(tset); | |
1837 | } else { | |
1838 | tset->cur_cgrp = tset->single.cgrp; | |
1839 | return tset->single.task; | |
1840 | } | |
1841 | } | |
1842 | EXPORT_SYMBOL_GPL(cgroup_taskset_first); | |
1843 | ||
1844 | /** | |
1845 | * cgroup_taskset_next - iterate to the next task in taskset | |
1846 | * @tset: taskset of interest | |
1847 | * | |
1848 | * Return the next task in @tset. Iteration must have been initialized | |
1849 | * with cgroup_taskset_first(). | |
1850 | */ | |
1851 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
1852 | { | |
1853 | struct task_and_cgroup *tc; | |
1854 | ||
1855 | if (!tset->tc_array || tset->idx >= tset->tc_array_len) | |
1856 | return NULL; | |
1857 | ||
1858 | tc = flex_array_get(tset->tc_array, tset->idx++); | |
1859 | tset->cur_cgrp = tc->cgrp; | |
1860 | return tc->task; | |
1861 | } | |
1862 | EXPORT_SYMBOL_GPL(cgroup_taskset_next); | |
1863 | ||
1864 | /** | |
1865 | * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task | |
1866 | * @tset: taskset of interest | |
1867 | * | |
1868 | * Return the cgroup for the current (last returned) task of @tset. This | |
1869 | * function must be preceded by either cgroup_taskset_first() or | |
1870 | * cgroup_taskset_next(). | |
1871 | */ | |
1872 | struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset) | |
1873 | { | |
1874 | return tset->cur_cgrp; | |
1875 | } | |
1876 | EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup); | |
1877 | ||
1878 | /** | |
1879 | * cgroup_taskset_size - return the number of tasks in taskset | |
1880 | * @tset: taskset of interest | |
1881 | */ | |
1882 | int cgroup_taskset_size(struct cgroup_taskset *tset) | |
1883 | { | |
1884 | return tset->tc_array ? tset->tc_array_len : 1; | |
1885 | } | |
1886 | EXPORT_SYMBOL_GPL(cgroup_taskset_size); | |
1887 | ||
1888 | ||
74a1166d BB |
1889 | /* |
1890 | * cgroup_task_migrate - move a task from one cgroup to another. | |
1891 | * | |
1892 | * 'guarantee' is set if the caller promises that a new css_set for the task | |
1893 | * will already exist. If not set, this function might sleep, and can fail with | |
cd3d0952 | 1894 | * -ENOMEM. Must be called with cgroup_mutex and threadgroup locked. |
74a1166d | 1895 | */ |
61d1d219 MSB |
1896 | static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, |
1897 | struct task_struct *tsk, struct css_set *newcg) | |
74a1166d BB |
1898 | { |
1899 | struct css_set *oldcg; | |
74a1166d BB |
1900 | |
1901 | /* | |
026085ef MSB |
1902 | * We are synchronized through threadgroup_lock() against PF_EXITING |
1903 | * setting such that we can't race against cgroup_exit() changing the | |
1904 | * css_set to init_css_set and dropping the old one. | |
74a1166d | 1905 | */ |
c84cdf75 | 1906 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
74a1166d | 1907 | oldcg = tsk->cgroups; |
74a1166d | 1908 | |
74a1166d | 1909 | task_lock(tsk); |
74a1166d BB |
1910 | rcu_assign_pointer(tsk->cgroups, newcg); |
1911 | task_unlock(tsk); | |
1912 | ||
1913 | /* Update the css_set linked lists if we're using them */ | |
1914 | write_lock(&css_set_lock); | |
1915 | if (!list_empty(&tsk->cg_list)) | |
1916 | list_move(&tsk->cg_list, &newcg->tasks); | |
1917 | write_unlock(&css_set_lock); | |
1918 | ||
1919 | /* | |
1920 | * We just gained a reference on oldcg by taking it from the task. As | |
1921 | * trading it for newcg is protected by cgroup_mutex, we're safe to drop | |
1922 | * it here; it will be freed under RCU. | |
1923 | */ | |
1924 | put_css_set(oldcg); | |
1925 | ||
1926 | set_bit(CGRP_RELEASABLE, &oldcgrp->flags); | |
74a1166d BB |
1927 | } |
1928 | ||
a043e3b2 LZ |
1929 | /** |
1930 | * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' | |
1931 | * @cgrp: the cgroup the task is attaching to | |
1932 | * @tsk: the task to be attached | |
bbcb81d0 | 1933 | * |
cd3d0952 TH |
1934 | * Call with cgroup_mutex and threadgroup locked. May take task_lock of |
1935 | * @tsk during call. | |
bbcb81d0 | 1936 | */ |
956db3ca | 1937 | int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) |
bbcb81d0 | 1938 | { |
8f121918 | 1939 | int retval = 0; |
2468c723 | 1940 | struct cgroup_subsys *ss, *failed_ss = NULL; |
bd89aabc | 1941 | struct cgroup *oldcgrp; |
bd89aabc | 1942 | struct cgroupfs_root *root = cgrp->root; |
2f7ee569 | 1943 | struct cgroup_taskset tset = { }; |
61d1d219 | 1944 | struct css_set *newcg; |
bbcb81d0 | 1945 | |
cd3d0952 TH |
1946 | /* @tsk either already exited or can't exit until the end */ |
1947 | if (tsk->flags & PF_EXITING) | |
1948 | return -ESRCH; | |
bbcb81d0 PM |
1949 | |
1950 | /* Nothing to do if the task is already in that cgroup */ | |
7717f7ba | 1951 | oldcgrp = task_cgroup_from_root(tsk, root); |
bd89aabc | 1952 | if (cgrp == oldcgrp) |
bbcb81d0 PM |
1953 | return 0; |
1954 | ||
2f7ee569 TH |
1955 | tset.single.task = tsk; |
1956 | tset.single.cgrp = oldcgrp; | |
1957 | ||
bbcb81d0 PM |
1958 | for_each_subsys(root, ss) { |
1959 | if (ss->can_attach) { | |
761b3ef5 | 1960 | retval = ss->can_attach(cgrp, &tset); |
2468c723 DN |
1961 | if (retval) { |
1962 | /* | |
1963 | * Remember on which subsystem the can_attach() | |
1964 | * failed, so that we only call cancel_attach() | |
1965 | * against the subsystems whose can_attach() | |
1966 | * succeeded. (See below) | |
1967 | */ | |
1968 | failed_ss = ss; | |
1969 | goto out; | |
1970 | } | |
bbcb81d0 PM |
1971 | } |
1972 | } | |
1973 | ||
61d1d219 MSB |
1974 | newcg = find_css_set(tsk->cgroups, cgrp); |
1975 | if (!newcg) { | |
1976 | retval = -ENOMEM; | |
2468c723 | 1977 | goto out; |
61d1d219 MSB |
1978 | } |
1979 | ||
1980 | cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg); | |
817929ec | 1981 | |
bbcb81d0 | 1982 | for_each_subsys(root, ss) { |
e18f6318 | 1983 | if (ss->attach) |
761b3ef5 | 1984 | ss->attach(cgrp, &tset); |
bbcb81d0 | 1985 | } |
74a1166d | 1986 | |
bbcb81d0 | 1987 | synchronize_rcu(); |
ec64f515 KH |
1988 | |
1989 | /* | |
1990 | * wake up rmdir() waiter. the rmdir should fail since the cgroup | |
1991 | * is no longer empty. | |
1992 | */ | |
88703267 | 1993 | cgroup_wakeup_rmdir_waiter(cgrp); |
2468c723 DN |
1994 | out: |
1995 | if (retval) { | |
1996 | for_each_subsys(root, ss) { | |
1997 | if (ss == failed_ss) | |
1998 | /* | |
1999 | * This subsystem was the one that failed the | |
2000 | * can_attach() check earlier, so we don't need | |
2001 | * to call cancel_attach() against it or any | |
2002 | * remaining subsystems. | |
2003 | */ | |
2004 | break; | |
2005 | if (ss->cancel_attach) | |
761b3ef5 | 2006 | ss->cancel_attach(cgrp, &tset); |
2468c723 DN |
2007 | } |
2008 | } | |
2009 | return retval; | |
bbcb81d0 PM |
2010 | } |
2011 | ||
d7926ee3 | 2012 | /** |
31583bb0 MT |
2013 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' |
2014 | * @from: attach to all cgroups of a given task | |
d7926ee3 SS |
2015 | * @tsk: the task to be attached |
2016 | */ | |
31583bb0 | 2017 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) |
d7926ee3 SS |
2018 | { |
2019 | struct cgroupfs_root *root; | |
d7926ee3 SS |
2020 | int retval = 0; |
2021 | ||
2022 | cgroup_lock(); | |
2023 | for_each_active_root(root) { | |
31583bb0 MT |
2024 | struct cgroup *from_cg = task_cgroup_from_root(from, root); |
2025 | ||
2026 | retval = cgroup_attach_task(from_cg, tsk); | |
d7926ee3 SS |
2027 | if (retval) |
2028 | break; | |
2029 | } | |
2030 | cgroup_unlock(); | |
2031 | ||
2032 | return retval; | |
2033 | } | |
31583bb0 | 2034 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); |
d7926ee3 | 2035 | |
74a1166d BB |
2036 | /** |
2037 | * cgroup_attach_proc - attach all threads in a threadgroup to a cgroup | |
2038 | * @cgrp: the cgroup to attach to | |
2039 | * @leader: the threadgroup leader task_struct of the group to be attached | |
2040 | * | |
257058ae TH |
2041 | * Call holding cgroup_mutex and the group_rwsem of the leader. Will take |
2042 | * task_lock of each thread in leader's threadgroup individually in turn. | |
74a1166d | 2043 | */ |
1c6c3fad | 2044 | static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) |
74a1166d BB |
2045 | { |
2046 | int retval, i, group_size; | |
2047 | struct cgroup_subsys *ss, *failed_ss = NULL; | |
74a1166d | 2048 | /* guaranteed to be initialized later, but the compiler needs this */ |
74a1166d BB |
2049 | struct cgroupfs_root *root = cgrp->root; |
2050 | /* threadgroup list cursor and array */ | |
2051 | struct task_struct *tsk; | |
134d3373 | 2052 | struct task_and_cgroup *tc; |
d846687d | 2053 | struct flex_array *group; |
2f7ee569 | 2054 | struct cgroup_taskset tset = { }; |
74a1166d BB |
2055 | |
2056 | /* | |
2057 | * step 0: in order to do expensive, possibly blocking operations for | |
2058 | * every thread, we cannot iterate the thread group list, since it needs | |
2059 | * rcu or tasklist locked. instead, build an array of all threads in the | |
257058ae TH |
2060 | * group - group_rwsem prevents new threads from appearing, and if |
2061 | * threads exit, this will just be an over-estimate. | |
74a1166d BB |
2062 | */ |
2063 | group_size = get_nr_threads(leader); | |
d846687d | 2064 | /* flex_array supports very large thread-groups better than kmalloc. */ |
134d3373 | 2065 | group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL); |
74a1166d BB |
2066 | if (!group) |
2067 | return -ENOMEM; | |
d846687d BB |
2068 | /* pre-allocate to guarantee space while iterating in rcu read-side. */ |
2069 | retval = flex_array_prealloc(group, 0, group_size - 1, GFP_KERNEL); | |
2070 | if (retval) | |
2071 | goto out_free_group_list; | |
74a1166d | 2072 | |
74a1166d BB |
2073 | tsk = leader; |
2074 | i = 0; | |
fb5d2b4c MSB |
2075 | /* |
2076 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
2077 | * already PF_EXITING could be freed from underneath us unless we | |
2078 | * take an rcu_read_lock. | |
2079 | */ | |
2080 | rcu_read_lock(); | |
74a1166d | 2081 | do { |
134d3373 TH |
2082 | struct task_and_cgroup ent; |
2083 | ||
cd3d0952 TH |
2084 | /* @tsk either already exited or can't exit until the end */ |
2085 | if (tsk->flags & PF_EXITING) | |
2086 | continue; | |
2087 | ||
74a1166d BB |
2088 | /* as per above, nr_threads may decrease, but not increase. */ |
2089 | BUG_ON(i >= group_size); | |
134d3373 TH |
2090 | ent.task = tsk; |
2091 | ent.cgrp = task_cgroup_from_root(tsk, root); | |
892a2b90 MSB |
2092 | /* nothing to do if this task is already in the cgroup */ |
2093 | if (ent.cgrp == cgrp) | |
2094 | continue; | |
61d1d219 MSB |
2095 | /* |
2096 | * saying GFP_ATOMIC has no effect here because we did prealloc | |
2097 | * earlier, but it's good form to communicate our expectations. | |
2098 | */ | |
134d3373 | 2099 | retval = flex_array_put(group, i, &ent, GFP_ATOMIC); |
d846687d | 2100 | BUG_ON(retval != 0); |
74a1166d BB |
2101 | i++; |
2102 | } while_each_thread(leader, tsk); | |
fb5d2b4c | 2103 | rcu_read_unlock(); |
74a1166d BB |
2104 | /* remember the number of threads in the array for later. */ |
2105 | group_size = i; | |
2f7ee569 TH |
2106 | tset.tc_array = group; |
2107 | tset.tc_array_len = group_size; | |
74a1166d | 2108 | |
134d3373 TH |
2109 | /* methods shouldn't be called if no task is actually migrating */ |
2110 | retval = 0; | |
892a2b90 | 2111 | if (!group_size) |
b07ef774 | 2112 | goto out_free_group_list; |
134d3373 | 2113 | |
74a1166d BB |
2114 | /* |
2115 | * step 1: check that we can legitimately attach to the cgroup. | |
2116 | */ | |
2117 | for_each_subsys(root, ss) { | |
2118 | if (ss->can_attach) { | |
761b3ef5 | 2119 | retval = ss->can_attach(cgrp, &tset); |
74a1166d BB |
2120 | if (retval) { |
2121 | failed_ss = ss; | |
2122 | goto out_cancel_attach; | |
2123 | } | |
2124 | } | |
74a1166d BB |
2125 | } |
2126 | ||
2127 | /* | |
2128 | * step 2: make sure css_sets exist for all threads to be migrated. | |
2129 | * we use find_css_set, which allocates a new one if necessary. | |
2130 | */ | |
74a1166d | 2131 | for (i = 0; i < group_size; i++) { |
134d3373 | 2132 | tc = flex_array_get(group, i); |
61d1d219 MSB |
2133 | tc->cg = find_css_set(tc->task->cgroups, cgrp); |
2134 | if (!tc->cg) { | |
2135 | retval = -ENOMEM; | |
2136 | goto out_put_css_set_refs; | |
74a1166d BB |
2137 | } |
2138 | } | |
2139 | ||
2140 | /* | |
494c167c TH |
2141 | * step 3: now that we're guaranteed success wrt the css_sets, |
2142 | * proceed to move all tasks to the new cgroup. There are no | |
2143 | * failure cases after here, so this is the commit point. | |
74a1166d | 2144 | */ |
74a1166d | 2145 | for (i = 0; i < group_size; i++) { |
134d3373 | 2146 | tc = flex_array_get(group, i); |
61d1d219 | 2147 | cgroup_task_migrate(cgrp, tc->cgrp, tc->task, tc->cg); |
74a1166d BB |
2148 | } |
2149 | /* nothing is sensitive to fork() after this point. */ | |
2150 | ||
2151 | /* | |
494c167c | 2152 | * step 4: do subsystem attach callbacks. |
74a1166d BB |
2153 | */ |
2154 | for_each_subsys(root, ss) { | |
2155 | if (ss->attach) | |
761b3ef5 | 2156 | ss->attach(cgrp, &tset); |
74a1166d BB |
2157 | } |
2158 | ||
2159 | /* | |
2160 | * step 5: success! and cleanup | |
2161 | */ | |
2162 | synchronize_rcu(); | |
2163 | cgroup_wakeup_rmdir_waiter(cgrp); | |
2164 | retval = 0; | |
61d1d219 MSB |
2165 | out_put_css_set_refs: |
2166 | if (retval) { | |
2167 | for (i = 0; i < group_size; i++) { | |
2168 | tc = flex_array_get(group, i); | |
2169 | if (!tc->cg) | |
2170 | break; | |
2171 | put_css_set(tc->cg); | |
2172 | } | |
74a1166d BB |
2173 | } |
2174 | out_cancel_attach: | |
74a1166d BB |
2175 | if (retval) { |
2176 | for_each_subsys(root, ss) { | |
494c167c | 2177 | if (ss == failed_ss) |
74a1166d | 2178 | break; |
74a1166d | 2179 | if (ss->cancel_attach) |
761b3ef5 | 2180 | ss->cancel_attach(cgrp, &tset); |
74a1166d BB |
2181 | } |
2182 | } | |
74a1166d | 2183 | out_free_group_list: |
d846687d | 2184 | flex_array_free(group); |
74a1166d BB |
2185 | return retval; |
2186 | } | |
2187 | ||
2188 | /* | |
2189 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 TH |
2190 | * function to attach either it or all tasks in its threadgroup. Will lock |
2191 | * cgroup_mutex and threadgroup; may take task_lock of task. | |
bbcb81d0 | 2192 | */ |
74a1166d | 2193 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) |
bbcb81d0 | 2194 | { |
bbcb81d0 | 2195 | struct task_struct *tsk; |
c69e8d9c | 2196 | const struct cred *cred = current_cred(), *tcred; |
bbcb81d0 PM |
2197 | int ret; |
2198 | ||
74a1166d BB |
2199 | if (!cgroup_lock_live_group(cgrp)) |
2200 | return -ENODEV; | |
2201 | ||
b78949eb MSB |
2202 | retry_find_task: |
2203 | rcu_read_lock(); | |
bbcb81d0 | 2204 | if (pid) { |
73507f33 | 2205 | tsk = find_task_by_vpid(pid); |
74a1166d BB |
2206 | if (!tsk) { |
2207 | rcu_read_unlock(); | |
b78949eb MSB |
2208 | ret= -ESRCH; |
2209 | goto out_unlock_cgroup; | |
bbcb81d0 | 2210 | } |
74a1166d BB |
2211 | /* |
2212 | * even if we're attaching all tasks in the thread group, we | |
2213 | * only need to check permissions on one of them. | |
2214 | */ | |
c69e8d9c DH |
2215 | tcred = __task_cred(tsk); |
2216 | if (cred->euid && | |
2217 | cred->euid != tcred->uid && | |
2218 | cred->euid != tcred->suid) { | |
2219 | rcu_read_unlock(); | |
b78949eb MSB |
2220 | ret = -EACCES; |
2221 | goto out_unlock_cgroup; | |
bbcb81d0 | 2222 | } |
b78949eb MSB |
2223 | } else |
2224 | tsk = current; | |
cd3d0952 TH |
2225 | |
2226 | if (threadgroup) | |
b78949eb MSB |
2227 | tsk = tsk->group_leader; |
2228 | get_task_struct(tsk); | |
2229 | rcu_read_unlock(); | |
2230 | ||
2231 | threadgroup_lock(tsk); | |
2232 | if (threadgroup) { | |
2233 | if (!thread_group_leader(tsk)) { | |
2234 | /* | |
2235 | * a race with de_thread from another thread's exec() | |
2236 | * may strip us of our leadership, if this happens, | |
2237 | * there is no choice but to throw this task away and | |
2238 | * try again; this is | |
2239 | * "double-double-toil-and-trouble-check locking". | |
2240 | */ | |
2241 | threadgroup_unlock(tsk); | |
2242 | put_task_struct(tsk); | |
2243 | goto retry_find_task; | |
2244 | } | |
74a1166d | 2245 | ret = cgroup_attach_proc(cgrp, tsk); |
b78949eb | 2246 | } else |
74a1166d | 2247 | ret = cgroup_attach_task(cgrp, tsk); |
cd3d0952 TH |
2248 | threadgroup_unlock(tsk); |
2249 | ||
bbcb81d0 | 2250 | put_task_struct(tsk); |
b78949eb | 2251 | out_unlock_cgroup: |
74a1166d | 2252 | cgroup_unlock(); |
bbcb81d0 PM |
2253 | return ret; |
2254 | } | |
2255 | ||
af351026 | 2256 | static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) |
74a1166d BB |
2257 | { |
2258 | return attach_task_by_pid(cgrp, pid, false); | |
2259 | } | |
2260 | ||
2261 | static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid) | |
af351026 | 2262 | { |
b78949eb | 2263 | return attach_task_by_pid(cgrp, tgid, true); |
af351026 PM |
2264 | } |
2265 | ||
e788e066 PM |
2266 | /** |
2267 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
2268 | * @cgrp: the cgroup to be checked for liveness | |
2269 | * | |
84eea842 PM |
2270 | * On success, returns true; the lock should be later released with |
2271 | * cgroup_unlock(). On failure returns false with no lock held. | |
e788e066 | 2272 | */ |
84eea842 | 2273 | bool cgroup_lock_live_group(struct cgroup *cgrp) |
e788e066 PM |
2274 | { |
2275 | mutex_lock(&cgroup_mutex); | |
2276 | if (cgroup_is_removed(cgrp)) { | |
2277 | mutex_unlock(&cgroup_mutex); | |
2278 | return false; | |
2279 | } | |
2280 | return true; | |
2281 | } | |
67523c48 | 2282 | EXPORT_SYMBOL_GPL(cgroup_lock_live_group); |
e788e066 PM |
2283 | |
2284 | static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, | |
2285 | const char *buffer) | |
2286 | { | |
2287 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); | |
f4a2589f EK |
2288 | if (strlen(buffer) >= PATH_MAX) |
2289 | return -EINVAL; | |
e788e066 PM |
2290 | if (!cgroup_lock_live_group(cgrp)) |
2291 | return -ENODEV; | |
e25e2cbb | 2292 | mutex_lock(&cgroup_root_mutex); |
e788e066 | 2293 | strcpy(cgrp->root->release_agent_path, buffer); |
e25e2cbb | 2294 | mutex_unlock(&cgroup_root_mutex); |
84eea842 | 2295 | cgroup_unlock(); |
e788e066 PM |
2296 | return 0; |
2297 | } | |
2298 | ||
2299 | static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, | |
2300 | struct seq_file *seq) | |
2301 | { | |
2302 | if (!cgroup_lock_live_group(cgrp)) | |
2303 | return -ENODEV; | |
2304 | seq_puts(seq, cgrp->root->release_agent_path); | |
2305 | seq_putc(seq, '\n'); | |
84eea842 | 2306 | cgroup_unlock(); |
e788e066 PM |
2307 | return 0; |
2308 | } | |
2309 | ||
84eea842 PM |
2310 | /* A buffer size big enough for numbers or short strings */ |
2311 | #define CGROUP_LOCAL_BUFFER_SIZE 64 | |
2312 | ||
e73d2c61 | 2313 | static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, |
f4c753b7 PM |
2314 | struct file *file, |
2315 | const char __user *userbuf, | |
2316 | size_t nbytes, loff_t *unused_ppos) | |
355e0c48 | 2317 | { |
84eea842 | 2318 | char buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
355e0c48 | 2319 | int retval = 0; |
355e0c48 PM |
2320 | char *end; |
2321 | ||
2322 | if (!nbytes) | |
2323 | return -EINVAL; | |
2324 | if (nbytes >= sizeof(buffer)) | |
2325 | return -E2BIG; | |
2326 | if (copy_from_user(buffer, userbuf, nbytes)) | |
2327 | return -EFAULT; | |
2328 | ||
2329 | buffer[nbytes] = 0; /* nul-terminate */ | |
e73d2c61 | 2330 | if (cft->write_u64) { |
478988d3 | 2331 | u64 val = simple_strtoull(strstrip(buffer), &end, 0); |
e73d2c61 PM |
2332 | if (*end) |
2333 | return -EINVAL; | |
2334 | retval = cft->write_u64(cgrp, cft, val); | |
2335 | } else { | |
478988d3 | 2336 | s64 val = simple_strtoll(strstrip(buffer), &end, 0); |
e73d2c61 PM |
2337 | if (*end) |
2338 | return -EINVAL; | |
2339 | retval = cft->write_s64(cgrp, cft, val); | |
2340 | } | |
355e0c48 PM |
2341 | if (!retval) |
2342 | retval = nbytes; | |
2343 | return retval; | |
2344 | } | |
2345 | ||
db3b1497 PM |
2346 | static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, |
2347 | struct file *file, | |
2348 | const char __user *userbuf, | |
2349 | size_t nbytes, loff_t *unused_ppos) | |
2350 | { | |
84eea842 | 2351 | char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
db3b1497 PM |
2352 | int retval = 0; |
2353 | size_t max_bytes = cft->max_write_len; | |
2354 | char *buffer = local_buffer; | |
2355 | ||
2356 | if (!max_bytes) | |
2357 | max_bytes = sizeof(local_buffer) - 1; | |
2358 | if (nbytes >= max_bytes) | |
2359 | return -E2BIG; | |
2360 | /* Allocate a dynamic buffer if we need one */ | |
2361 | if (nbytes >= sizeof(local_buffer)) { | |
2362 | buffer = kmalloc(nbytes + 1, GFP_KERNEL); | |
2363 | if (buffer == NULL) | |
2364 | return -ENOMEM; | |
2365 | } | |
5a3eb9f6 LZ |
2366 | if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { |
2367 | retval = -EFAULT; | |
2368 | goto out; | |
2369 | } | |
db3b1497 PM |
2370 | |
2371 | buffer[nbytes] = 0; /* nul-terminate */ | |
478988d3 | 2372 | retval = cft->write_string(cgrp, cft, strstrip(buffer)); |
db3b1497 PM |
2373 | if (!retval) |
2374 | retval = nbytes; | |
5a3eb9f6 | 2375 | out: |
db3b1497 PM |
2376 | if (buffer != local_buffer) |
2377 | kfree(buffer); | |
2378 | return retval; | |
2379 | } | |
2380 | ||
ddbcc7e8 PM |
2381 | static ssize_t cgroup_file_write(struct file *file, const char __user *buf, |
2382 | size_t nbytes, loff_t *ppos) | |
2383 | { | |
2384 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 2385 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 2386 | |
75139b82 | 2387 | if (cgroup_is_removed(cgrp)) |
ddbcc7e8 | 2388 | return -ENODEV; |
355e0c48 | 2389 | if (cft->write) |
bd89aabc | 2390 | return cft->write(cgrp, cft, file, buf, nbytes, ppos); |
e73d2c61 PM |
2391 | if (cft->write_u64 || cft->write_s64) |
2392 | return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); | |
db3b1497 PM |
2393 | if (cft->write_string) |
2394 | return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); | |
d447ea2f PE |
2395 | if (cft->trigger) { |
2396 | int ret = cft->trigger(cgrp, (unsigned int)cft->private); | |
2397 | return ret ? ret : nbytes; | |
2398 | } | |
355e0c48 | 2399 | return -EINVAL; |
ddbcc7e8 PM |
2400 | } |
2401 | ||
f4c753b7 PM |
2402 | static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, |
2403 | struct file *file, | |
2404 | char __user *buf, size_t nbytes, | |
2405 | loff_t *ppos) | |
ddbcc7e8 | 2406 | { |
84eea842 | 2407 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
f4c753b7 | 2408 | u64 val = cft->read_u64(cgrp, cft); |
ddbcc7e8 PM |
2409 | int len = sprintf(tmp, "%llu\n", (unsigned long long) val); |
2410 | ||
2411 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2412 | } | |
2413 | ||
e73d2c61 PM |
2414 | static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft, |
2415 | struct file *file, | |
2416 | char __user *buf, size_t nbytes, | |
2417 | loff_t *ppos) | |
2418 | { | |
84eea842 | 2419 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
e73d2c61 PM |
2420 | s64 val = cft->read_s64(cgrp, cft); |
2421 | int len = sprintf(tmp, "%lld\n", (long long) val); | |
2422 | ||
2423 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2424 | } | |
2425 | ||
ddbcc7e8 PM |
2426 | static ssize_t cgroup_file_read(struct file *file, char __user *buf, |
2427 | size_t nbytes, loff_t *ppos) | |
2428 | { | |
2429 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 2430 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 2431 | |
75139b82 | 2432 | if (cgroup_is_removed(cgrp)) |
ddbcc7e8 PM |
2433 | return -ENODEV; |
2434 | ||
2435 | if (cft->read) | |
bd89aabc | 2436 | return cft->read(cgrp, cft, file, buf, nbytes, ppos); |
f4c753b7 PM |
2437 | if (cft->read_u64) |
2438 | return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos); | |
e73d2c61 PM |
2439 | if (cft->read_s64) |
2440 | return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos); | |
ddbcc7e8 PM |
2441 | return -EINVAL; |
2442 | } | |
2443 | ||
91796569 PM |
2444 | /* |
2445 | * seqfile ops/methods for returning structured data. Currently just | |
2446 | * supports string->u64 maps, but can be extended in future. | |
2447 | */ | |
2448 | ||
2449 | struct cgroup_seqfile_state { | |
2450 | struct cftype *cft; | |
2451 | struct cgroup *cgroup; | |
2452 | }; | |
2453 | ||
2454 | static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) | |
2455 | { | |
2456 | struct seq_file *sf = cb->state; | |
2457 | return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); | |
2458 | } | |
2459 | ||
2460 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) | |
2461 | { | |
2462 | struct cgroup_seqfile_state *state = m->private; | |
2463 | struct cftype *cft = state->cft; | |
29486df3 SH |
2464 | if (cft->read_map) { |
2465 | struct cgroup_map_cb cb = { | |
2466 | .fill = cgroup_map_add, | |
2467 | .state = m, | |
2468 | }; | |
2469 | return cft->read_map(state->cgroup, cft, &cb); | |
2470 | } | |
2471 | return cft->read_seq_string(state->cgroup, cft, m); | |
91796569 PM |
2472 | } |
2473 | ||
96930a63 | 2474 | static int cgroup_seqfile_release(struct inode *inode, struct file *file) |
91796569 PM |
2475 | { |
2476 | struct seq_file *seq = file->private_data; | |
2477 | kfree(seq->private); | |
2478 | return single_release(inode, file); | |
2479 | } | |
2480 | ||
828c0950 | 2481 | static const struct file_operations cgroup_seqfile_operations = { |
91796569 | 2482 | .read = seq_read, |
e788e066 | 2483 | .write = cgroup_file_write, |
91796569 PM |
2484 | .llseek = seq_lseek, |
2485 | .release = cgroup_seqfile_release, | |
2486 | }; | |
2487 | ||
ddbcc7e8 PM |
2488 | static int cgroup_file_open(struct inode *inode, struct file *file) |
2489 | { | |
2490 | int err; | |
2491 | struct cftype *cft; | |
2492 | ||
2493 | err = generic_file_open(inode, file); | |
2494 | if (err) | |
2495 | return err; | |
ddbcc7e8 | 2496 | cft = __d_cft(file->f_dentry); |
75139b82 | 2497 | |
29486df3 | 2498 | if (cft->read_map || cft->read_seq_string) { |
91796569 PM |
2499 | struct cgroup_seqfile_state *state = |
2500 | kzalloc(sizeof(*state), GFP_USER); | |
2501 | if (!state) | |
2502 | return -ENOMEM; | |
2503 | state->cft = cft; | |
2504 | state->cgroup = __d_cgrp(file->f_dentry->d_parent); | |
2505 | file->f_op = &cgroup_seqfile_operations; | |
2506 | err = single_open(file, cgroup_seqfile_show, state); | |
2507 | if (err < 0) | |
2508 | kfree(state); | |
2509 | } else if (cft->open) | |
ddbcc7e8 PM |
2510 | err = cft->open(inode, file); |
2511 | else | |
2512 | err = 0; | |
2513 | ||
2514 | return err; | |
2515 | } | |
2516 | ||
2517 | static int cgroup_file_release(struct inode *inode, struct file *file) | |
2518 | { | |
2519 | struct cftype *cft = __d_cft(file->f_dentry); | |
2520 | if (cft->release) | |
2521 | return cft->release(inode, file); | |
2522 | return 0; | |
2523 | } | |
2524 | ||
2525 | /* | |
2526 | * cgroup_rename - Only allow simple rename of directories in place. | |
2527 | */ | |
2528 | static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2529 | struct inode *new_dir, struct dentry *new_dentry) | |
2530 | { | |
2531 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) | |
2532 | return -ENOTDIR; | |
2533 | if (new_dentry->d_inode) | |
2534 | return -EEXIST; | |
2535 | if (old_dir != new_dir) | |
2536 | return -EIO; | |
2537 | return simple_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2538 | } | |
2539 | ||
828c0950 | 2540 | static const struct file_operations cgroup_file_operations = { |
ddbcc7e8 PM |
2541 | .read = cgroup_file_read, |
2542 | .write = cgroup_file_write, | |
2543 | .llseek = generic_file_llseek, | |
2544 | .open = cgroup_file_open, | |
2545 | .release = cgroup_file_release, | |
2546 | }; | |
2547 | ||
6e1d5dcc | 2548 | static const struct inode_operations cgroup_dir_inode_operations = { |
c72a04e3 | 2549 | .lookup = cgroup_lookup, |
ddbcc7e8 PM |
2550 | .mkdir = cgroup_mkdir, |
2551 | .rmdir = cgroup_rmdir, | |
2552 | .rename = cgroup_rename, | |
2553 | }; | |
2554 | ||
c72a04e3 AV |
2555 | static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) |
2556 | { | |
2557 | if (dentry->d_name.len > NAME_MAX) | |
2558 | return ERR_PTR(-ENAMETOOLONG); | |
2559 | d_add(dentry, NULL); | |
2560 | return NULL; | |
2561 | } | |
2562 | ||
0dea1168 KS |
2563 | /* |
2564 | * Check if a file is a control file | |
2565 | */ | |
2566 | static inline struct cftype *__file_cft(struct file *file) | |
2567 | { | |
2568 | if (file->f_dentry->d_inode->i_fop != &cgroup_file_operations) | |
2569 | return ERR_PTR(-EINVAL); | |
2570 | return __d_cft(file->f_dentry); | |
2571 | } | |
2572 | ||
a5e7ed32 | 2573 | static int cgroup_create_file(struct dentry *dentry, umode_t mode, |
5adcee1d NP |
2574 | struct super_block *sb) |
2575 | { | |
ddbcc7e8 PM |
2576 | struct inode *inode; |
2577 | ||
2578 | if (!dentry) | |
2579 | return -ENOENT; | |
2580 | if (dentry->d_inode) | |
2581 | return -EEXIST; | |
2582 | ||
2583 | inode = cgroup_new_inode(mode, sb); | |
2584 | if (!inode) | |
2585 | return -ENOMEM; | |
2586 | ||
2587 | if (S_ISDIR(mode)) { | |
2588 | inode->i_op = &cgroup_dir_inode_operations; | |
2589 | inode->i_fop = &simple_dir_operations; | |
2590 | ||
2591 | /* start off with i_nlink == 2 (for "." entry) */ | |
2592 | inc_nlink(inode); | |
2593 | ||
2594 | /* start with the directory inode held, so that we can | |
2595 | * populate it without racing with another mkdir */ | |
817929ec | 2596 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); |
ddbcc7e8 PM |
2597 | } else if (S_ISREG(mode)) { |
2598 | inode->i_size = 0; | |
2599 | inode->i_fop = &cgroup_file_operations; | |
2600 | } | |
ddbcc7e8 PM |
2601 | d_instantiate(dentry, inode); |
2602 | dget(dentry); /* Extra count - pin the dentry in core */ | |
2603 | return 0; | |
2604 | } | |
2605 | ||
2606 | /* | |
a043e3b2 LZ |
2607 | * cgroup_create_dir - create a directory for an object. |
2608 | * @cgrp: the cgroup we create the directory for. It must have a valid | |
2609 | * ->parent field. And we are going to fill its ->dentry field. | |
2610 | * @dentry: dentry of the new cgroup | |
2611 | * @mode: mode to set on new directory. | |
ddbcc7e8 | 2612 | */ |
bd89aabc | 2613 | static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry, |
a5e7ed32 | 2614 | umode_t mode) |
ddbcc7e8 PM |
2615 | { |
2616 | struct dentry *parent; | |
2617 | int error = 0; | |
2618 | ||
bd89aabc PM |
2619 | parent = cgrp->parent->dentry; |
2620 | error = cgroup_create_file(dentry, S_IFDIR | mode, cgrp->root->sb); | |
ddbcc7e8 | 2621 | if (!error) { |
bd89aabc | 2622 | dentry->d_fsdata = cgrp; |
ddbcc7e8 | 2623 | inc_nlink(parent->d_inode); |
a47295e6 | 2624 | rcu_assign_pointer(cgrp->dentry, dentry); |
ddbcc7e8 PM |
2625 | dget(dentry); |
2626 | } | |
2627 | dput(dentry); | |
2628 | ||
2629 | return error; | |
2630 | } | |
2631 | ||
099fca32 LZ |
2632 | /** |
2633 | * cgroup_file_mode - deduce file mode of a control file | |
2634 | * @cft: the control file in question | |
2635 | * | |
2636 | * returns cft->mode if ->mode is not 0 | |
2637 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
2638 | * returns S_IRUGO if it has only a read handler | |
2639 | * returns S_IWUSR if it has only a write hander | |
2640 | */ | |
a5e7ed32 | 2641 | static umode_t cgroup_file_mode(const struct cftype *cft) |
099fca32 | 2642 | { |
a5e7ed32 | 2643 | umode_t mode = 0; |
099fca32 LZ |
2644 | |
2645 | if (cft->mode) | |
2646 | return cft->mode; | |
2647 | ||
2648 | if (cft->read || cft->read_u64 || cft->read_s64 || | |
2649 | cft->read_map || cft->read_seq_string) | |
2650 | mode |= S_IRUGO; | |
2651 | ||
2652 | if (cft->write || cft->write_u64 || cft->write_s64 || | |
2653 | cft->write_string || cft->trigger) | |
2654 | mode |= S_IWUSR; | |
2655 | ||
2656 | return mode; | |
2657 | } | |
2658 | ||
db0416b6 TH |
2659 | static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
2660 | const struct cftype *cft) | |
ddbcc7e8 | 2661 | { |
bd89aabc | 2662 | struct dentry *dir = cgrp->dentry; |
05ef1d7c | 2663 | struct cgroup *parent = __d_cgrp(dir); |
ddbcc7e8 | 2664 | struct dentry *dentry; |
05ef1d7c | 2665 | struct cfent *cfe; |
ddbcc7e8 | 2666 | int error; |
a5e7ed32 | 2667 | umode_t mode; |
ddbcc7e8 | 2668 | char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; |
8e3f6541 TH |
2669 | |
2670 | /* does @cft->flags tell us to skip creation on @cgrp? */ | |
2671 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) | |
2672 | return 0; | |
2673 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) | |
2674 | return 0; | |
2675 | ||
bd89aabc | 2676 | if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) { |
ddbcc7e8 PM |
2677 | strcpy(name, subsys->name); |
2678 | strcat(name, "."); | |
2679 | } | |
2680 | strcat(name, cft->name); | |
05ef1d7c | 2681 | |
ddbcc7e8 | 2682 | BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); |
05ef1d7c TH |
2683 | |
2684 | cfe = kzalloc(sizeof(*cfe), GFP_KERNEL); | |
2685 | if (!cfe) | |
2686 | return -ENOMEM; | |
2687 | ||
ddbcc7e8 | 2688 | dentry = lookup_one_len(name, dir, strlen(name)); |
05ef1d7c | 2689 | if (IS_ERR(dentry)) { |
ddbcc7e8 | 2690 | error = PTR_ERR(dentry); |
05ef1d7c TH |
2691 | goto out; |
2692 | } | |
2693 | ||
2694 | mode = cgroup_file_mode(cft); | |
2695 | error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb); | |
2696 | if (!error) { | |
2697 | cfe->type = (void *)cft; | |
2698 | cfe->dentry = dentry; | |
2699 | dentry->d_fsdata = cfe; | |
2700 | list_add_tail(&cfe->node, &parent->files); | |
2701 | cfe = NULL; | |
2702 | } | |
2703 | dput(dentry); | |
2704 | out: | |
2705 | kfree(cfe); | |
ddbcc7e8 PM |
2706 | return error; |
2707 | } | |
2708 | ||
79578621 TH |
2709 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
2710 | const struct cftype cfts[], bool is_add) | |
ddbcc7e8 | 2711 | { |
db0416b6 TH |
2712 | const struct cftype *cft; |
2713 | int err, ret = 0; | |
2714 | ||
2715 | for (cft = cfts; cft->name[0] != '\0'; cft++) { | |
79578621 TH |
2716 | if (is_add) |
2717 | err = cgroup_add_file(cgrp, subsys, cft); | |
2718 | else | |
2719 | err = cgroup_rm_file(cgrp, cft); | |
db0416b6 | 2720 | if (err) { |
79578621 TH |
2721 | pr_warning("cgroup_addrm_files: failed to %s %s, err=%d\n", |
2722 | is_add ? "add" : "remove", cft->name, err); | |
db0416b6 TH |
2723 | ret = err; |
2724 | } | |
ddbcc7e8 | 2725 | } |
db0416b6 | 2726 | return ret; |
ddbcc7e8 PM |
2727 | } |
2728 | ||
8e3f6541 TH |
2729 | static DEFINE_MUTEX(cgroup_cft_mutex); |
2730 | ||
2731 | static void cgroup_cfts_prepare(void) | |
2732 | __acquires(&cgroup_cft_mutex) __acquires(&cgroup_mutex) | |
2733 | { | |
2734 | /* | |
2735 | * Thanks to the entanglement with vfs inode locking, we can't walk | |
2736 | * the existing cgroups under cgroup_mutex and create files. | |
2737 | * Instead, we increment reference on all cgroups and build list of | |
2738 | * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure | |
2739 | * exclusive access to the field. | |
2740 | */ | |
2741 | mutex_lock(&cgroup_cft_mutex); | |
2742 | mutex_lock(&cgroup_mutex); | |
2743 | } | |
2744 | ||
2745 | static void cgroup_cfts_commit(struct cgroup_subsys *ss, | |
79578621 | 2746 | const struct cftype *cfts, bool is_add) |
8e3f6541 TH |
2747 | __releases(&cgroup_mutex) __releases(&cgroup_cft_mutex) |
2748 | { | |
2749 | LIST_HEAD(pending); | |
2750 | struct cgroup *cgrp, *n; | |
8e3f6541 TH |
2751 | |
2752 | /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */ | |
2753 | if (cfts && ss->root != &rootnode) { | |
2754 | list_for_each_entry(cgrp, &ss->root->allcg_list, allcg_node) { | |
2755 | dget(cgrp->dentry); | |
2756 | list_add_tail(&cgrp->cft_q_node, &pending); | |
2757 | } | |
2758 | } | |
2759 | ||
2760 | mutex_unlock(&cgroup_mutex); | |
2761 | ||
2762 | /* | |
2763 | * All new cgroups will see @cfts update on @ss->cftsets. Add/rm | |
2764 | * files for all cgroups which were created before. | |
2765 | */ | |
2766 | list_for_each_entry_safe(cgrp, n, &pending, cft_q_node) { | |
2767 | struct inode *inode = cgrp->dentry->d_inode; | |
2768 | ||
2769 | mutex_lock(&inode->i_mutex); | |
2770 | mutex_lock(&cgroup_mutex); | |
2771 | if (!cgroup_is_removed(cgrp)) | |
79578621 | 2772 | cgroup_addrm_files(cgrp, ss, cfts, is_add); |
8e3f6541 TH |
2773 | mutex_unlock(&cgroup_mutex); |
2774 | mutex_unlock(&inode->i_mutex); | |
2775 | ||
2776 | list_del_init(&cgrp->cft_q_node); | |
2777 | dput(cgrp->dentry); | |
2778 | } | |
2779 | ||
2780 | mutex_unlock(&cgroup_cft_mutex); | |
2781 | } | |
2782 | ||
2783 | /** | |
2784 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
2785 | * @ss: target cgroup subsystem | |
2786 | * @cfts: zero-length name terminated array of cftypes | |
2787 | * | |
2788 | * Register @cfts to @ss. Files described by @cfts are created for all | |
2789 | * existing cgroups to which @ss is attached and all future cgroups will | |
2790 | * have them too. This function can be called anytime whether @ss is | |
2791 | * attached or not. | |
2792 | * | |
2793 | * Returns 0 on successful registration, -errno on failure. Note that this | |
2794 | * function currently returns 0 as long as @cfts registration is successful | |
2795 | * even if some file creation attempts on existing cgroups fail. | |
2796 | */ | |
2797 | int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts) | |
2798 | { | |
2799 | struct cftype_set *set; | |
2800 | ||
2801 | set = kzalloc(sizeof(*set), GFP_KERNEL); | |
2802 | if (!set) | |
2803 | return -ENOMEM; | |
2804 | ||
2805 | cgroup_cfts_prepare(); | |
2806 | set->cfts = cfts; | |
2807 | list_add_tail(&set->node, &ss->cftsets); | |
79578621 | 2808 | cgroup_cfts_commit(ss, cfts, true); |
8e3f6541 TH |
2809 | |
2810 | return 0; | |
2811 | } | |
2812 | EXPORT_SYMBOL_GPL(cgroup_add_cftypes); | |
2813 | ||
79578621 TH |
2814 | /** |
2815 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
2816 | * @ss: target cgroup subsystem | |
2817 | * @cfts: zero-length name terminated array of cftypes | |
2818 | * | |
2819 | * Unregister @cfts from @ss. Files described by @cfts are removed from | |
2820 | * all existing cgroups to which @ss is attached and all future cgroups | |
2821 | * won't have them either. This function can be called anytime whether @ss | |
2822 | * is attached or not. | |
2823 | * | |
2824 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2825 | * registered with @ss. | |
2826 | */ | |
2827 | int cgroup_rm_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts) | |
2828 | { | |
2829 | struct cftype_set *set; | |
2830 | ||
2831 | cgroup_cfts_prepare(); | |
2832 | ||
2833 | list_for_each_entry(set, &ss->cftsets, node) { | |
2834 | if (set->cfts == cfts) { | |
2835 | list_del_init(&set->node); | |
2836 | cgroup_cfts_commit(ss, cfts, false); | |
2837 | return 0; | |
2838 | } | |
2839 | } | |
2840 | ||
2841 | cgroup_cfts_commit(ss, NULL, false); | |
2842 | return -ENOENT; | |
2843 | } | |
2844 | ||
a043e3b2 LZ |
2845 | /** |
2846 | * cgroup_task_count - count the number of tasks in a cgroup. | |
2847 | * @cgrp: the cgroup in question | |
2848 | * | |
2849 | * Return the number of tasks in the cgroup. | |
2850 | */ | |
bd89aabc | 2851 | int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
2852 | { |
2853 | int count = 0; | |
71cbb949 | 2854 | struct cg_cgroup_link *link; |
817929ec PM |
2855 | |
2856 | read_lock(&css_set_lock); | |
71cbb949 | 2857 | list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) { |
146aa1bd | 2858 | count += atomic_read(&link->cg->refcount); |
817929ec PM |
2859 | } |
2860 | read_unlock(&css_set_lock); | |
bbcb81d0 PM |
2861 | return count; |
2862 | } | |
2863 | ||
817929ec PM |
2864 | /* |
2865 | * Advance a list_head iterator. The iterator should be positioned at | |
2866 | * the start of a css_set | |
2867 | */ | |
bd89aabc | 2868 | static void cgroup_advance_iter(struct cgroup *cgrp, |
7717f7ba | 2869 | struct cgroup_iter *it) |
817929ec PM |
2870 | { |
2871 | struct list_head *l = it->cg_link; | |
2872 | struct cg_cgroup_link *link; | |
2873 | struct css_set *cg; | |
2874 | ||
2875 | /* Advance to the next non-empty css_set */ | |
2876 | do { | |
2877 | l = l->next; | |
bd89aabc | 2878 | if (l == &cgrp->css_sets) { |
817929ec PM |
2879 | it->cg_link = NULL; |
2880 | return; | |
2881 | } | |
bd89aabc | 2882 | link = list_entry(l, struct cg_cgroup_link, cgrp_link_list); |
817929ec PM |
2883 | cg = link->cg; |
2884 | } while (list_empty(&cg->tasks)); | |
2885 | it->cg_link = l; | |
2886 | it->task = cg->tasks.next; | |
2887 | } | |
2888 | ||
31a7df01 CW |
2889 | /* |
2890 | * To reduce the fork() overhead for systems that are not actually | |
2891 | * using their cgroups capability, we don't maintain the lists running | |
2892 | * through each css_set to its tasks until we see the list actually | |
2893 | * used - in other words after the first call to cgroup_iter_start(). | |
31a7df01 | 2894 | */ |
3df91fe3 | 2895 | static void cgroup_enable_task_cg_lists(void) |
31a7df01 CW |
2896 | { |
2897 | struct task_struct *p, *g; | |
2898 | write_lock(&css_set_lock); | |
2899 | use_task_css_set_links = 1; | |
3ce3230a FW |
2900 | /* |
2901 | * We need tasklist_lock because RCU is not safe against | |
2902 | * while_each_thread(). Besides, a forking task that has passed | |
2903 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
2904 | * is not guaranteed to have its child immediately visible in the | |
2905 | * tasklist if we walk through it with RCU. | |
2906 | */ | |
2907 | read_lock(&tasklist_lock); | |
31a7df01 CW |
2908 | do_each_thread(g, p) { |
2909 | task_lock(p); | |
0e04388f LZ |
2910 | /* |
2911 | * We should check if the process is exiting, otherwise | |
2912 | * it will race with cgroup_exit() in that the list | |
2913 | * entry won't be deleted though the process has exited. | |
2914 | */ | |
2915 | if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) | |
31a7df01 CW |
2916 | list_add(&p->cg_list, &p->cgroups->tasks); |
2917 | task_unlock(p); | |
2918 | } while_each_thread(g, p); | |
3ce3230a | 2919 | read_unlock(&tasklist_lock); |
31a7df01 CW |
2920 | write_unlock(&css_set_lock); |
2921 | } | |
2922 | ||
bd89aabc | 2923 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) |
c6ca5750 | 2924 | __acquires(css_set_lock) |
817929ec PM |
2925 | { |
2926 | /* | |
2927 | * The first time anyone tries to iterate across a cgroup, | |
2928 | * we need to enable the list linking each css_set to its | |
2929 | * tasks, and fix up all existing tasks. | |
2930 | */ | |
31a7df01 CW |
2931 | if (!use_task_css_set_links) |
2932 | cgroup_enable_task_cg_lists(); | |
2933 | ||
817929ec | 2934 | read_lock(&css_set_lock); |
bd89aabc PM |
2935 | it->cg_link = &cgrp->css_sets; |
2936 | cgroup_advance_iter(cgrp, it); | |
817929ec PM |
2937 | } |
2938 | ||
bd89aabc | 2939 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
817929ec PM |
2940 | struct cgroup_iter *it) |
2941 | { | |
2942 | struct task_struct *res; | |
2943 | struct list_head *l = it->task; | |
2019f634 | 2944 | struct cg_cgroup_link *link; |
817929ec PM |
2945 | |
2946 | /* If the iterator cg is NULL, we have no tasks */ | |
2947 | if (!it->cg_link) | |
2948 | return NULL; | |
2949 | res = list_entry(l, struct task_struct, cg_list); | |
2950 | /* Advance iterator to find next entry */ | |
2951 | l = l->next; | |
2019f634 LJ |
2952 | link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list); |
2953 | if (l == &link->cg->tasks) { | |
817929ec PM |
2954 | /* We reached the end of this task list - move on to |
2955 | * the next cg_cgroup_link */ | |
bd89aabc | 2956 | cgroup_advance_iter(cgrp, it); |
817929ec PM |
2957 | } else { |
2958 | it->task = l; | |
2959 | } | |
2960 | return res; | |
2961 | } | |
2962 | ||
bd89aabc | 2963 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it) |
c6ca5750 | 2964 | __releases(css_set_lock) |
817929ec PM |
2965 | { |
2966 | read_unlock(&css_set_lock); | |
2967 | } | |
2968 | ||
31a7df01 CW |
2969 | static inline int started_after_time(struct task_struct *t1, |
2970 | struct timespec *time, | |
2971 | struct task_struct *t2) | |
2972 | { | |
2973 | int start_diff = timespec_compare(&t1->start_time, time); | |
2974 | if (start_diff > 0) { | |
2975 | return 1; | |
2976 | } else if (start_diff < 0) { | |
2977 | return 0; | |
2978 | } else { | |
2979 | /* | |
2980 | * Arbitrarily, if two processes started at the same | |
2981 | * time, we'll say that the lower pointer value | |
2982 | * started first. Note that t2 may have exited by now | |
2983 | * so this may not be a valid pointer any longer, but | |
2984 | * that's fine - it still serves to distinguish | |
2985 | * between two tasks started (effectively) simultaneously. | |
2986 | */ | |
2987 | return t1 > t2; | |
2988 | } | |
2989 | } | |
2990 | ||
2991 | /* | |
2992 | * This function is a callback from heap_insert() and is used to order | |
2993 | * the heap. | |
2994 | * In this case we order the heap in descending task start time. | |
2995 | */ | |
2996 | static inline int started_after(void *p1, void *p2) | |
2997 | { | |
2998 | struct task_struct *t1 = p1; | |
2999 | struct task_struct *t2 = p2; | |
3000 | return started_after_time(t1, &t2->start_time, t2); | |
3001 | } | |
3002 | ||
3003 | /** | |
3004 | * cgroup_scan_tasks - iterate though all the tasks in a cgroup | |
3005 | * @scan: struct cgroup_scanner containing arguments for the scan | |
3006 | * | |
3007 | * Arguments include pointers to callback functions test_task() and | |
3008 | * process_task(). | |
3009 | * Iterate through all the tasks in a cgroup, calling test_task() for each, | |
3010 | * and if it returns true, call process_task() for it also. | |
3011 | * The test_task pointer may be NULL, meaning always true (select all tasks). | |
3012 | * Effectively duplicates cgroup_iter_{start,next,end}() | |
3013 | * but does not lock css_set_lock for the call to process_task(). | |
3014 | * The struct cgroup_scanner may be embedded in any structure of the caller's | |
3015 | * creation. | |
3016 | * It is guaranteed that process_task() will act on every task that | |
3017 | * is a member of the cgroup for the duration of this call. This | |
3018 | * function may or may not call process_task() for tasks that exit | |
3019 | * or move to a different cgroup during the call, or are forked or | |
3020 | * move into the cgroup during the call. | |
3021 | * | |
3022 | * Note that test_task() may be called with locks held, and may in some | |
3023 | * situations be called multiple times for the same task, so it should | |
3024 | * be cheap. | |
3025 | * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been | |
3026 | * pre-allocated and will be used for heap operations (and its "gt" member will | |
3027 | * be overwritten), else a temporary heap will be used (allocation of which | |
3028 | * may cause this function to fail). | |
3029 | */ | |
3030 | int cgroup_scan_tasks(struct cgroup_scanner *scan) | |
3031 | { | |
3032 | int retval, i; | |
3033 | struct cgroup_iter it; | |
3034 | struct task_struct *p, *dropped; | |
3035 | /* Never dereference latest_task, since it's not refcounted */ | |
3036 | struct task_struct *latest_task = NULL; | |
3037 | struct ptr_heap tmp_heap; | |
3038 | struct ptr_heap *heap; | |
3039 | struct timespec latest_time = { 0, 0 }; | |
3040 | ||
3041 | if (scan->heap) { | |
3042 | /* The caller supplied our heap and pre-allocated its memory */ | |
3043 | heap = scan->heap; | |
3044 | heap->gt = &started_after; | |
3045 | } else { | |
3046 | /* We need to allocate our own heap memory */ | |
3047 | heap = &tmp_heap; | |
3048 | retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); | |
3049 | if (retval) | |
3050 | /* cannot allocate the heap */ | |
3051 | return retval; | |
3052 | } | |
3053 | ||
3054 | again: | |
3055 | /* | |
3056 | * Scan tasks in the cgroup, using the scanner's "test_task" callback | |
3057 | * to determine which are of interest, and using the scanner's | |
3058 | * "process_task" callback to process any of them that need an update. | |
3059 | * Since we don't want to hold any locks during the task updates, | |
3060 | * gather tasks to be processed in a heap structure. | |
3061 | * The heap is sorted by descending task start time. | |
3062 | * If the statically-sized heap fills up, we overflow tasks that | |
3063 | * started later, and in future iterations only consider tasks that | |
3064 | * started after the latest task in the previous pass. This | |
3065 | * guarantees forward progress and that we don't miss any tasks. | |
3066 | */ | |
3067 | heap->size = 0; | |
3068 | cgroup_iter_start(scan->cg, &it); | |
3069 | while ((p = cgroup_iter_next(scan->cg, &it))) { | |
3070 | /* | |
3071 | * Only affect tasks that qualify per the caller's callback, | |
3072 | * if he provided one | |
3073 | */ | |
3074 | if (scan->test_task && !scan->test_task(p, scan)) | |
3075 | continue; | |
3076 | /* | |
3077 | * Only process tasks that started after the last task | |
3078 | * we processed | |
3079 | */ | |
3080 | if (!started_after_time(p, &latest_time, latest_task)) | |
3081 | continue; | |
3082 | dropped = heap_insert(heap, p); | |
3083 | if (dropped == NULL) { | |
3084 | /* | |
3085 | * The new task was inserted; the heap wasn't | |
3086 | * previously full | |
3087 | */ | |
3088 | get_task_struct(p); | |
3089 | } else if (dropped != p) { | |
3090 | /* | |
3091 | * The new task was inserted, and pushed out a | |
3092 | * different task | |
3093 | */ | |
3094 | get_task_struct(p); | |
3095 | put_task_struct(dropped); | |
3096 | } | |
3097 | /* | |
3098 | * Else the new task was newer than anything already in | |
3099 | * the heap and wasn't inserted | |
3100 | */ | |
3101 | } | |
3102 | cgroup_iter_end(scan->cg, &it); | |
3103 | ||
3104 | if (heap->size) { | |
3105 | for (i = 0; i < heap->size; i++) { | |
4fe91d51 | 3106 | struct task_struct *q = heap->ptrs[i]; |
31a7df01 | 3107 | if (i == 0) { |
4fe91d51 PJ |
3108 | latest_time = q->start_time; |
3109 | latest_task = q; | |
31a7df01 CW |
3110 | } |
3111 | /* Process the task per the caller's callback */ | |
4fe91d51 PJ |
3112 | scan->process_task(q, scan); |
3113 | put_task_struct(q); | |
31a7df01 CW |
3114 | } |
3115 | /* | |
3116 | * If we had to process any tasks at all, scan again | |
3117 | * in case some of them were in the middle of forking | |
3118 | * children that didn't get processed. | |
3119 | * Not the most efficient way to do it, but it avoids | |
3120 | * having to take callback_mutex in the fork path | |
3121 | */ | |
3122 | goto again; | |
3123 | } | |
3124 | if (heap == &tmp_heap) | |
3125 | heap_free(&tmp_heap); | |
3126 | return 0; | |
3127 | } | |
3128 | ||
bbcb81d0 | 3129 | /* |
102a775e | 3130 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
3131 | * |
3132 | * Reading this file can return large amounts of data if a cgroup has | |
3133 | * *lots* of attached tasks. So it may need several calls to read(), | |
3134 | * but we cannot guarantee that the information we produce is correct | |
3135 | * unless we produce it entirely atomically. | |
3136 | * | |
bbcb81d0 | 3137 | */ |
bbcb81d0 | 3138 | |
24528255 LZ |
3139 | /* which pidlist file are we talking about? */ |
3140 | enum cgroup_filetype { | |
3141 | CGROUP_FILE_PROCS, | |
3142 | CGROUP_FILE_TASKS, | |
3143 | }; | |
3144 | ||
3145 | /* | |
3146 | * A pidlist is a list of pids that virtually represents the contents of one | |
3147 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
3148 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
3149 | * to the cgroup. | |
3150 | */ | |
3151 | struct cgroup_pidlist { | |
3152 | /* | |
3153 | * used to find which pidlist is wanted. doesn't change as long as | |
3154 | * this particular list stays in the list. | |
3155 | */ | |
3156 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
3157 | /* array of xids */ | |
3158 | pid_t *list; | |
3159 | /* how many elements the above list has */ | |
3160 | int length; | |
3161 | /* how many files are using the current array */ | |
3162 | int use_count; | |
3163 | /* each of these stored in a list by its cgroup */ | |
3164 | struct list_head links; | |
3165 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
3166 | struct cgroup *owner; | |
3167 | /* protects the other fields */ | |
3168 | struct rw_semaphore mutex; | |
3169 | }; | |
3170 | ||
d1d9fd33 BB |
3171 | /* |
3172 | * The following two functions "fix" the issue where there are more pids | |
3173 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
3174 | * TODO: replace with a kernel-wide solution to this problem | |
3175 | */ | |
3176 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
3177 | static void *pidlist_allocate(int count) | |
3178 | { | |
3179 | if (PIDLIST_TOO_LARGE(count)) | |
3180 | return vmalloc(count * sizeof(pid_t)); | |
3181 | else | |
3182 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
3183 | } | |
3184 | static void pidlist_free(void *p) | |
3185 | { | |
3186 | if (is_vmalloc_addr(p)) | |
3187 | vfree(p); | |
3188 | else | |
3189 | kfree(p); | |
3190 | } | |
3191 | static void *pidlist_resize(void *p, int newcount) | |
3192 | { | |
3193 | void *newlist; | |
3194 | /* note: if new alloc fails, old p will still be valid either way */ | |
3195 | if (is_vmalloc_addr(p)) { | |
3196 | newlist = vmalloc(newcount * sizeof(pid_t)); | |
3197 | if (!newlist) | |
3198 | return NULL; | |
3199 | memcpy(newlist, p, newcount * sizeof(pid_t)); | |
3200 | vfree(p); | |
3201 | } else { | |
3202 | newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL); | |
3203 | } | |
3204 | return newlist; | |
3205 | } | |
3206 | ||
bbcb81d0 | 3207 | /* |
102a775e BB |
3208 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
3209 | * If the new stripped list is sufficiently smaller and there's enough memory | |
3210 | * to allocate a new buffer, will let go of the unneeded memory. Returns the | |
3211 | * number of unique elements. | |
bbcb81d0 | 3212 | */ |
102a775e BB |
3213 | /* is the size difference enough that we should re-allocate the array? */ |
3214 | #define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new)) | |
3215 | static int pidlist_uniq(pid_t **p, int length) | |
bbcb81d0 | 3216 | { |
102a775e BB |
3217 | int src, dest = 1; |
3218 | pid_t *list = *p; | |
3219 | pid_t *newlist; | |
3220 | ||
3221 | /* | |
3222 | * we presume the 0th element is unique, so i starts at 1. trivial | |
3223 | * edge cases first; no work needs to be done for either | |
3224 | */ | |
3225 | if (length == 0 || length == 1) | |
3226 | return length; | |
3227 | /* src and dest walk down the list; dest counts unique elements */ | |
3228 | for (src = 1; src < length; src++) { | |
3229 | /* find next unique element */ | |
3230 | while (list[src] == list[src-1]) { | |
3231 | src++; | |
3232 | if (src == length) | |
3233 | goto after; | |
3234 | } | |
3235 | /* dest always points to where the next unique element goes */ | |
3236 | list[dest] = list[src]; | |
3237 | dest++; | |
3238 | } | |
3239 | after: | |
3240 | /* | |
3241 | * if the length difference is large enough, we want to allocate a | |
3242 | * smaller buffer to save memory. if this fails due to out of memory, | |
3243 | * we'll just stay with what we've got. | |
3244 | */ | |
3245 | if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) { | |
d1d9fd33 | 3246 | newlist = pidlist_resize(list, dest); |
102a775e BB |
3247 | if (newlist) |
3248 | *p = newlist; | |
3249 | } | |
3250 | return dest; | |
3251 | } | |
3252 | ||
3253 | static int cmppid(const void *a, const void *b) | |
3254 | { | |
3255 | return *(pid_t *)a - *(pid_t *)b; | |
3256 | } | |
3257 | ||
72a8cb30 BB |
3258 | /* |
3259 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
3260 | * returns with the lock on that pidlist already held, and takes care | |
3261 | * of the use count, or returns NULL with no locks held if we're out of | |
3262 | * memory. | |
3263 | */ | |
3264 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, | |
3265 | enum cgroup_filetype type) | |
3266 | { | |
3267 | struct cgroup_pidlist *l; | |
3268 | /* don't need task_nsproxy() if we're looking at ourself */ | |
b70cc5fd LZ |
3269 | struct pid_namespace *ns = current->nsproxy->pid_ns; |
3270 | ||
72a8cb30 BB |
3271 | /* |
3272 | * We can't drop the pidlist_mutex before taking the l->mutex in case | |
3273 | * the last ref-holder is trying to remove l from the list at the same | |
3274 | * time. Holding the pidlist_mutex precludes somebody taking whichever | |
3275 | * list we find out from under us - compare release_pid_array(). | |
3276 | */ | |
3277 | mutex_lock(&cgrp->pidlist_mutex); | |
3278 | list_for_each_entry(l, &cgrp->pidlists, links) { | |
3279 | if (l->key.type == type && l->key.ns == ns) { | |
72a8cb30 BB |
3280 | /* make sure l doesn't vanish out from under us */ |
3281 | down_write(&l->mutex); | |
3282 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
3283 | return l; |
3284 | } | |
3285 | } | |
3286 | /* entry not found; create a new one */ | |
3287 | l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); | |
3288 | if (!l) { | |
3289 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
3290 | return l; |
3291 | } | |
3292 | init_rwsem(&l->mutex); | |
3293 | down_write(&l->mutex); | |
3294 | l->key.type = type; | |
b70cc5fd | 3295 | l->key.ns = get_pid_ns(ns); |
72a8cb30 BB |
3296 | l->use_count = 0; /* don't increment here */ |
3297 | l->list = NULL; | |
3298 | l->owner = cgrp; | |
3299 | list_add(&l->links, &cgrp->pidlists); | |
3300 | mutex_unlock(&cgrp->pidlist_mutex); | |
3301 | return l; | |
3302 | } | |
3303 | ||
102a775e BB |
3304 | /* |
3305 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
3306 | */ | |
72a8cb30 BB |
3307 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
3308 | struct cgroup_pidlist **lp) | |
102a775e BB |
3309 | { |
3310 | pid_t *array; | |
3311 | int length; | |
3312 | int pid, n = 0; /* used for populating the array */ | |
817929ec PM |
3313 | struct cgroup_iter it; |
3314 | struct task_struct *tsk; | |
102a775e BB |
3315 | struct cgroup_pidlist *l; |
3316 | ||
3317 | /* | |
3318 | * If cgroup gets more users after we read count, we won't have | |
3319 | * enough space - tough. This race is indistinguishable to the | |
3320 | * caller from the case that the additional cgroup users didn't | |
3321 | * show up until sometime later on. | |
3322 | */ | |
3323 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 3324 | array = pidlist_allocate(length); |
102a775e BB |
3325 | if (!array) |
3326 | return -ENOMEM; | |
3327 | /* now, populate the array */ | |
bd89aabc PM |
3328 | cgroup_iter_start(cgrp, &it); |
3329 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
102a775e | 3330 | if (unlikely(n == length)) |
817929ec | 3331 | break; |
102a775e | 3332 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
3333 | if (type == CGROUP_FILE_PROCS) |
3334 | pid = task_tgid_vnr(tsk); | |
3335 | else | |
3336 | pid = task_pid_vnr(tsk); | |
102a775e BB |
3337 | if (pid > 0) /* make sure to only use valid results */ |
3338 | array[n++] = pid; | |
817929ec | 3339 | } |
bd89aabc | 3340 | cgroup_iter_end(cgrp, &it); |
102a775e BB |
3341 | length = n; |
3342 | /* now sort & (if procs) strip out duplicates */ | |
3343 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 3344 | if (type == CGROUP_FILE_PROCS) |
102a775e | 3345 | length = pidlist_uniq(&array, length); |
72a8cb30 BB |
3346 | l = cgroup_pidlist_find(cgrp, type); |
3347 | if (!l) { | |
d1d9fd33 | 3348 | pidlist_free(array); |
72a8cb30 | 3349 | return -ENOMEM; |
102a775e | 3350 | } |
72a8cb30 | 3351 | /* store array, freeing old if necessary - lock already held */ |
d1d9fd33 | 3352 | pidlist_free(l->list); |
102a775e BB |
3353 | l->list = array; |
3354 | l->length = length; | |
3355 | l->use_count++; | |
3356 | up_write(&l->mutex); | |
72a8cb30 | 3357 | *lp = l; |
102a775e | 3358 | return 0; |
bbcb81d0 PM |
3359 | } |
3360 | ||
846c7bb0 | 3361 | /** |
a043e3b2 | 3362 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
3363 | * @stats: cgroupstats to fill information into |
3364 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
3365 | * been requested. | |
a043e3b2 LZ |
3366 | * |
3367 | * Build and fill cgroupstats so that taskstats can export it to user | |
3368 | * space. | |
846c7bb0 BS |
3369 | */ |
3370 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
3371 | { | |
3372 | int ret = -EINVAL; | |
bd89aabc | 3373 | struct cgroup *cgrp; |
846c7bb0 BS |
3374 | struct cgroup_iter it; |
3375 | struct task_struct *tsk; | |
33d283be | 3376 | |
846c7bb0 | 3377 | /* |
33d283be LZ |
3378 | * Validate dentry by checking the superblock operations, |
3379 | * and make sure it's a directory. | |
846c7bb0 | 3380 | */ |
33d283be LZ |
3381 | if (dentry->d_sb->s_op != &cgroup_ops || |
3382 | !S_ISDIR(dentry->d_inode->i_mode)) | |
846c7bb0 BS |
3383 | goto err; |
3384 | ||
3385 | ret = 0; | |
bd89aabc | 3386 | cgrp = dentry->d_fsdata; |
846c7bb0 | 3387 | |
bd89aabc PM |
3388 | cgroup_iter_start(cgrp, &it); |
3389 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
846c7bb0 BS |
3390 | switch (tsk->state) { |
3391 | case TASK_RUNNING: | |
3392 | stats->nr_running++; | |
3393 | break; | |
3394 | case TASK_INTERRUPTIBLE: | |
3395 | stats->nr_sleeping++; | |
3396 | break; | |
3397 | case TASK_UNINTERRUPTIBLE: | |
3398 | stats->nr_uninterruptible++; | |
3399 | break; | |
3400 | case TASK_STOPPED: | |
3401 | stats->nr_stopped++; | |
3402 | break; | |
3403 | default: | |
3404 | if (delayacct_is_task_waiting_on_io(tsk)) | |
3405 | stats->nr_io_wait++; | |
3406 | break; | |
3407 | } | |
3408 | } | |
bd89aabc | 3409 | cgroup_iter_end(cgrp, &it); |
846c7bb0 | 3410 | |
846c7bb0 BS |
3411 | err: |
3412 | return ret; | |
3413 | } | |
3414 | ||
8f3ff208 | 3415 | |
bbcb81d0 | 3416 | /* |
102a775e | 3417 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 3418 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 3419 | * in the cgroup->l->list array. |
bbcb81d0 | 3420 | */ |
cc31edce | 3421 | |
102a775e | 3422 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 3423 | { |
cc31edce PM |
3424 | /* |
3425 | * Initially we receive a position value that corresponds to | |
3426 | * one more than the last pid shown (or 0 on the first call or | |
3427 | * after a seek to the start). Use a binary-search to find the | |
3428 | * next pid to display, if any | |
3429 | */ | |
102a775e | 3430 | struct cgroup_pidlist *l = s->private; |
cc31edce PM |
3431 | int index = 0, pid = *pos; |
3432 | int *iter; | |
3433 | ||
102a775e | 3434 | down_read(&l->mutex); |
cc31edce | 3435 | if (pid) { |
102a775e | 3436 | int end = l->length; |
20777766 | 3437 | |
cc31edce PM |
3438 | while (index < end) { |
3439 | int mid = (index + end) / 2; | |
102a775e | 3440 | if (l->list[mid] == pid) { |
cc31edce PM |
3441 | index = mid; |
3442 | break; | |
102a775e | 3443 | } else if (l->list[mid] <= pid) |
cc31edce PM |
3444 | index = mid + 1; |
3445 | else | |
3446 | end = mid; | |
3447 | } | |
3448 | } | |
3449 | /* If we're off the end of the array, we're done */ | |
102a775e | 3450 | if (index >= l->length) |
cc31edce PM |
3451 | return NULL; |
3452 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 3453 | iter = l->list + index; |
cc31edce PM |
3454 | *pos = *iter; |
3455 | return iter; | |
3456 | } | |
3457 | ||
102a775e | 3458 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 3459 | { |
102a775e BB |
3460 | struct cgroup_pidlist *l = s->private; |
3461 | up_read(&l->mutex); | |
cc31edce PM |
3462 | } |
3463 | ||
102a775e | 3464 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 3465 | { |
102a775e BB |
3466 | struct cgroup_pidlist *l = s->private; |
3467 | pid_t *p = v; | |
3468 | pid_t *end = l->list + l->length; | |
cc31edce PM |
3469 | /* |
3470 | * Advance to the next pid in the array. If this goes off the | |
3471 | * end, we're done | |
3472 | */ | |
3473 | p++; | |
3474 | if (p >= end) { | |
3475 | return NULL; | |
3476 | } else { | |
3477 | *pos = *p; | |
3478 | return p; | |
3479 | } | |
3480 | } | |
3481 | ||
102a775e | 3482 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce PM |
3483 | { |
3484 | return seq_printf(s, "%d\n", *(int *)v); | |
3485 | } | |
bbcb81d0 | 3486 | |
102a775e BB |
3487 | /* |
3488 | * seq_operations functions for iterating on pidlists through seq_file - | |
3489 | * independent of whether it's tasks or procs | |
3490 | */ | |
3491 | static const struct seq_operations cgroup_pidlist_seq_operations = { | |
3492 | .start = cgroup_pidlist_start, | |
3493 | .stop = cgroup_pidlist_stop, | |
3494 | .next = cgroup_pidlist_next, | |
3495 | .show = cgroup_pidlist_show, | |
cc31edce PM |
3496 | }; |
3497 | ||
102a775e | 3498 | static void cgroup_release_pid_array(struct cgroup_pidlist *l) |
cc31edce | 3499 | { |
72a8cb30 BB |
3500 | /* |
3501 | * the case where we're the last user of this particular pidlist will | |
3502 | * have us remove it from the cgroup's list, which entails taking the | |
3503 | * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> | |
3504 | * pidlist_mutex, we have to take pidlist_mutex first. | |
3505 | */ | |
3506 | mutex_lock(&l->owner->pidlist_mutex); | |
102a775e BB |
3507 | down_write(&l->mutex); |
3508 | BUG_ON(!l->use_count); | |
3509 | if (!--l->use_count) { | |
72a8cb30 BB |
3510 | /* we're the last user if refcount is 0; remove and free */ |
3511 | list_del(&l->links); | |
3512 | mutex_unlock(&l->owner->pidlist_mutex); | |
d1d9fd33 | 3513 | pidlist_free(l->list); |
72a8cb30 BB |
3514 | put_pid_ns(l->key.ns); |
3515 | up_write(&l->mutex); | |
3516 | kfree(l); | |
3517 | return; | |
cc31edce | 3518 | } |
72a8cb30 | 3519 | mutex_unlock(&l->owner->pidlist_mutex); |
102a775e | 3520 | up_write(&l->mutex); |
bbcb81d0 PM |
3521 | } |
3522 | ||
102a775e | 3523 | static int cgroup_pidlist_release(struct inode *inode, struct file *file) |
cc31edce | 3524 | { |
102a775e | 3525 | struct cgroup_pidlist *l; |
cc31edce PM |
3526 | if (!(file->f_mode & FMODE_READ)) |
3527 | return 0; | |
102a775e BB |
3528 | /* |
3529 | * the seq_file will only be initialized if the file was opened for | |
3530 | * reading; hence we check if it's not null only in that case. | |
3531 | */ | |
3532 | l = ((struct seq_file *)file->private_data)->private; | |
3533 | cgroup_release_pid_array(l); | |
cc31edce PM |
3534 | return seq_release(inode, file); |
3535 | } | |
3536 | ||
102a775e | 3537 | static const struct file_operations cgroup_pidlist_operations = { |
cc31edce PM |
3538 | .read = seq_read, |
3539 | .llseek = seq_lseek, | |
3540 | .write = cgroup_file_write, | |
102a775e | 3541 | .release = cgroup_pidlist_release, |
cc31edce PM |
3542 | }; |
3543 | ||
bbcb81d0 | 3544 | /* |
102a775e BB |
3545 | * The following functions handle opens on a file that displays a pidlist |
3546 | * (tasks or procs). Prepare an array of the process/thread IDs of whoever's | |
3547 | * in the cgroup. | |
bbcb81d0 | 3548 | */ |
102a775e | 3549 | /* helper function for the two below it */ |
72a8cb30 | 3550 | static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) |
bbcb81d0 | 3551 | { |
bd89aabc | 3552 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
72a8cb30 | 3553 | struct cgroup_pidlist *l; |
cc31edce | 3554 | int retval; |
bbcb81d0 | 3555 | |
cc31edce | 3556 | /* Nothing to do for write-only files */ |
bbcb81d0 PM |
3557 | if (!(file->f_mode & FMODE_READ)) |
3558 | return 0; | |
3559 | ||
102a775e | 3560 | /* have the array populated */ |
72a8cb30 | 3561 | retval = pidlist_array_load(cgrp, type, &l); |
102a775e BB |
3562 | if (retval) |
3563 | return retval; | |
3564 | /* configure file information */ | |
3565 | file->f_op = &cgroup_pidlist_operations; | |
cc31edce | 3566 | |
102a775e | 3567 | retval = seq_open(file, &cgroup_pidlist_seq_operations); |
cc31edce | 3568 | if (retval) { |
102a775e | 3569 | cgroup_release_pid_array(l); |
cc31edce | 3570 | return retval; |
bbcb81d0 | 3571 | } |
102a775e | 3572 | ((struct seq_file *)file->private_data)->private = l; |
bbcb81d0 PM |
3573 | return 0; |
3574 | } | |
102a775e BB |
3575 | static int cgroup_tasks_open(struct inode *unused, struct file *file) |
3576 | { | |
72a8cb30 | 3577 | return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); |
102a775e BB |
3578 | } |
3579 | static int cgroup_procs_open(struct inode *unused, struct file *file) | |
3580 | { | |
72a8cb30 | 3581 | return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); |
102a775e | 3582 | } |
bbcb81d0 | 3583 | |
bd89aabc | 3584 | static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, |
81a6a5cd PM |
3585 | struct cftype *cft) |
3586 | { | |
bd89aabc | 3587 | return notify_on_release(cgrp); |
81a6a5cd PM |
3588 | } |
3589 | ||
6379c106 PM |
3590 | static int cgroup_write_notify_on_release(struct cgroup *cgrp, |
3591 | struct cftype *cft, | |
3592 | u64 val) | |
3593 | { | |
3594 | clear_bit(CGRP_RELEASABLE, &cgrp->flags); | |
3595 | if (val) | |
3596 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3597 | else | |
3598 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3599 | return 0; | |
3600 | } | |
3601 | ||
0dea1168 KS |
3602 | /* |
3603 | * Unregister event and free resources. | |
3604 | * | |
3605 | * Gets called from workqueue. | |
3606 | */ | |
3607 | static void cgroup_event_remove(struct work_struct *work) | |
3608 | { | |
3609 | struct cgroup_event *event = container_of(work, struct cgroup_event, | |
3610 | remove); | |
3611 | struct cgroup *cgrp = event->cgrp; | |
3612 | ||
0dea1168 KS |
3613 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); |
3614 | ||
3615 | eventfd_ctx_put(event->eventfd); | |
0dea1168 | 3616 | kfree(event); |
a0a4db54 | 3617 | dput(cgrp->dentry); |
0dea1168 KS |
3618 | } |
3619 | ||
3620 | /* | |
3621 | * Gets called on POLLHUP on eventfd when user closes it. | |
3622 | * | |
3623 | * Called with wqh->lock held and interrupts disabled. | |
3624 | */ | |
3625 | static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, | |
3626 | int sync, void *key) | |
3627 | { | |
3628 | struct cgroup_event *event = container_of(wait, | |
3629 | struct cgroup_event, wait); | |
3630 | struct cgroup *cgrp = event->cgrp; | |
3631 | unsigned long flags = (unsigned long)key; | |
3632 | ||
3633 | if (flags & POLLHUP) { | |
a93d2f17 | 3634 | __remove_wait_queue(event->wqh, &event->wait); |
0dea1168 KS |
3635 | spin_lock(&cgrp->event_list_lock); |
3636 | list_del(&event->list); | |
3637 | spin_unlock(&cgrp->event_list_lock); | |
3638 | /* | |
3639 | * We are in atomic context, but cgroup_event_remove() may | |
3640 | * sleep, so we have to call it in workqueue. | |
3641 | */ | |
3642 | schedule_work(&event->remove); | |
3643 | } | |
3644 | ||
3645 | return 0; | |
3646 | } | |
3647 | ||
3648 | static void cgroup_event_ptable_queue_proc(struct file *file, | |
3649 | wait_queue_head_t *wqh, poll_table *pt) | |
3650 | { | |
3651 | struct cgroup_event *event = container_of(pt, | |
3652 | struct cgroup_event, pt); | |
3653 | ||
3654 | event->wqh = wqh; | |
3655 | add_wait_queue(wqh, &event->wait); | |
3656 | } | |
3657 | ||
3658 | /* | |
3659 | * Parse input and register new cgroup event handler. | |
3660 | * | |
3661 | * Input must be in format '<event_fd> <control_fd> <args>'. | |
3662 | * Interpretation of args is defined by control file implementation. | |
3663 | */ | |
3664 | static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, | |
3665 | const char *buffer) | |
3666 | { | |
3667 | struct cgroup_event *event = NULL; | |
3668 | unsigned int efd, cfd; | |
3669 | struct file *efile = NULL; | |
3670 | struct file *cfile = NULL; | |
3671 | char *endp; | |
3672 | int ret; | |
3673 | ||
3674 | efd = simple_strtoul(buffer, &endp, 10); | |
3675 | if (*endp != ' ') | |
3676 | return -EINVAL; | |
3677 | buffer = endp + 1; | |
3678 | ||
3679 | cfd = simple_strtoul(buffer, &endp, 10); | |
3680 | if ((*endp != ' ') && (*endp != '\0')) | |
3681 | return -EINVAL; | |
3682 | buffer = endp + 1; | |
3683 | ||
3684 | event = kzalloc(sizeof(*event), GFP_KERNEL); | |
3685 | if (!event) | |
3686 | return -ENOMEM; | |
3687 | event->cgrp = cgrp; | |
3688 | INIT_LIST_HEAD(&event->list); | |
3689 | init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); | |
3690 | init_waitqueue_func_entry(&event->wait, cgroup_event_wake); | |
3691 | INIT_WORK(&event->remove, cgroup_event_remove); | |
3692 | ||
3693 | efile = eventfd_fget(efd); | |
3694 | if (IS_ERR(efile)) { | |
3695 | ret = PTR_ERR(efile); | |
3696 | goto fail; | |
3697 | } | |
3698 | ||
3699 | event->eventfd = eventfd_ctx_fileget(efile); | |
3700 | if (IS_ERR(event->eventfd)) { | |
3701 | ret = PTR_ERR(event->eventfd); | |
3702 | goto fail; | |
3703 | } | |
3704 | ||
3705 | cfile = fget(cfd); | |
3706 | if (!cfile) { | |
3707 | ret = -EBADF; | |
3708 | goto fail; | |
3709 | } | |
3710 | ||
3711 | /* the process need read permission on control file */ | |
3bfa784a AV |
3712 | /* AV: shouldn't we check that it's been opened for read instead? */ |
3713 | ret = inode_permission(cfile->f_path.dentry->d_inode, MAY_READ); | |
0dea1168 KS |
3714 | if (ret < 0) |
3715 | goto fail; | |
3716 | ||
3717 | event->cft = __file_cft(cfile); | |
3718 | if (IS_ERR(event->cft)) { | |
3719 | ret = PTR_ERR(event->cft); | |
3720 | goto fail; | |
3721 | } | |
3722 | ||
3723 | if (!event->cft->register_event || !event->cft->unregister_event) { | |
3724 | ret = -EINVAL; | |
3725 | goto fail; | |
3726 | } | |
3727 | ||
3728 | ret = event->cft->register_event(cgrp, event->cft, | |
3729 | event->eventfd, buffer); | |
3730 | if (ret) | |
3731 | goto fail; | |
3732 | ||
3733 | if (efile->f_op->poll(efile, &event->pt) & POLLHUP) { | |
3734 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); | |
3735 | ret = 0; | |
3736 | goto fail; | |
3737 | } | |
3738 | ||
a0a4db54 KS |
3739 | /* |
3740 | * Events should be removed after rmdir of cgroup directory, but before | |
3741 | * destroying subsystem state objects. Let's take reference to cgroup | |
3742 | * directory dentry to do that. | |
3743 | */ | |
3744 | dget(cgrp->dentry); | |
3745 | ||
0dea1168 KS |
3746 | spin_lock(&cgrp->event_list_lock); |
3747 | list_add(&event->list, &cgrp->event_list); | |
3748 | spin_unlock(&cgrp->event_list_lock); | |
3749 | ||
3750 | fput(cfile); | |
3751 | fput(efile); | |
3752 | ||
3753 | return 0; | |
3754 | ||
3755 | fail: | |
3756 | if (cfile) | |
3757 | fput(cfile); | |
3758 | ||
3759 | if (event && event->eventfd && !IS_ERR(event->eventfd)) | |
3760 | eventfd_ctx_put(event->eventfd); | |
3761 | ||
3762 | if (!IS_ERR_OR_NULL(efile)) | |
3763 | fput(efile); | |
3764 | ||
3765 | kfree(event); | |
3766 | ||
3767 | return ret; | |
3768 | } | |
3769 | ||
97978e6d DL |
3770 | static u64 cgroup_clone_children_read(struct cgroup *cgrp, |
3771 | struct cftype *cft) | |
3772 | { | |
3773 | return clone_children(cgrp); | |
3774 | } | |
3775 | ||
3776 | static int cgroup_clone_children_write(struct cgroup *cgrp, | |
3777 | struct cftype *cft, | |
3778 | u64 val) | |
3779 | { | |
3780 | if (val) | |
3781 | set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3782 | else | |
3783 | clear_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3784 | return 0; | |
3785 | } | |
3786 | ||
bbcb81d0 PM |
3787 | /* |
3788 | * for the common functions, 'private' gives the type of file | |
3789 | */ | |
102a775e BB |
3790 | /* for hysterical raisins, we can't put this on the older files */ |
3791 | #define CGROUP_FILE_GENERIC_PREFIX "cgroup." | |
81a6a5cd PM |
3792 | static struct cftype files[] = { |
3793 | { | |
3794 | .name = "tasks", | |
3795 | .open = cgroup_tasks_open, | |
af351026 | 3796 | .write_u64 = cgroup_tasks_write, |
102a775e | 3797 | .release = cgroup_pidlist_release, |
099fca32 | 3798 | .mode = S_IRUGO | S_IWUSR, |
81a6a5cd | 3799 | }, |
102a775e BB |
3800 | { |
3801 | .name = CGROUP_FILE_GENERIC_PREFIX "procs", | |
3802 | .open = cgroup_procs_open, | |
74a1166d | 3803 | .write_u64 = cgroup_procs_write, |
102a775e | 3804 | .release = cgroup_pidlist_release, |
74a1166d | 3805 | .mode = S_IRUGO | S_IWUSR, |
102a775e | 3806 | }, |
81a6a5cd PM |
3807 | { |
3808 | .name = "notify_on_release", | |
f4c753b7 | 3809 | .read_u64 = cgroup_read_notify_on_release, |
6379c106 | 3810 | .write_u64 = cgroup_write_notify_on_release, |
81a6a5cd | 3811 | }, |
0dea1168 KS |
3812 | { |
3813 | .name = CGROUP_FILE_GENERIC_PREFIX "event_control", | |
3814 | .write_string = cgroup_write_event_control, | |
3815 | .mode = S_IWUGO, | |
3816 | }, | |
97978e6d DL |
3817 | { |
3818 | .name = "cgroup.clone_children", | |
3819 | .read_u64 = cgroup_clone_children_read, | |
3820 | .write_u64 = cgroup_clone_children_write, | |
3821 | }, | |
6e6ff25b TH |
3822 | { |
3823 | .name = "release_agent", | |
3824 | .flags = CFTYPE_ONLY_ON_ROOT, | |
3825 | .read_seq_string = cgroup_release_agent_show, | |
3826 | .write_string = cgroup_release_agent_write, | |
3827 | .max_write_len = PATH_MAX, | |
3828 | }, | |
db0416b6 | 3829 | { } /* terminate */ |
bbcb81d0 PM |
3830 | }; |
3831 | ||
bd89aabc | 3832 | static int cgroup_populate_dir(struct cgroup *cgrp) |
ddbcc7e8 PM |
3833 | { |
3834 | int err; | |
3835 | struct cgroup_subsys *ss; | |
3836 | ||
79578621 | 3837 | err = cgroup_addrm_files(cgrp, NULL, files, true); |
bbcb81d0 PM |
3838 | if (err < 0) |
3839 | return err; | |
3840 | ||
8e3f6541 | 3841 | /* process cftsets of each subsystem */ |
bd89aabc | 3842 | for_each_subsys(cgrp->root, ss) { |
8e3f6541 TH |
3843 | struct cftype_set *set; |
3844 | ||
db0416b6 | 3845 | list_for_each_entry(set, &ss->cftsets, node) |
79578621 | 3846 | cgroup_addrm_files(cgrp, ss, set->cfts, true); |
ddbcc7e8 | 3847 | } |
8e3f6541 | 3848 | |
38460b48 KH |
3849 | /* This cgroup is ready now */ |
3850 | for_each_subsys(cgrp->root, ss) { | |
3851 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
3852 | /* | |
3853 | * Update id->css pointer and make this css visible from | |
3854 | * CSS ID functions. This pointer will be dereferened | |
3855 | * from RCU-read-side without locks. | |
3856 | */ | |
3857 | if (css->id) | |
3858 | rcu_assign_pointer(css->id->css, css); | |
3859 | } | |
ddbcc7e8 PM |
3860 | |
3861 | return 0; | |
3862 | } | |
3863 | ||
48ddbe19 TH |
3864 | static void css_dput_fn(struct work_struct *work) |
3865 | { | |
3866 | struct cgroup_subsys_state *css = | |
3867 | container_of(work, struct cgroup_subsys_state, dput_work); | |
3868 | ||
3869 | dput(css->cgroup->dentry); | |
3870 | } | |
3871 | ||
ddbcc7e8 PM |
3872 | static void init_cgroup_css(struct cgroup_subsys_state *css, |
3873 | struct cgroup_subsys *ss, | |
bd89aabc | 3874 | struct cgroup *cgrp) |
ddbcc7e8 | 3875 | { |
bd89aabc | 3876 | css->cgroup = cgrp; |
e7c5ec91 | 3877 | atomic_set(&css->refcnt, 1); |
ddbcc7e8 | 3878 | css->flags = 0; |
38460b48 | 3879 | css->id = NULL; |
bd89aabc | 3880 | if (cgrp == dummytop) |
ddbcc7e8 | 3881 | set_bit(CSS_ROOT, &css->flags); |
bd89aabc PM |
3882 | BUG_ON(cgrp->subsys[ss->subsys_id]); |
3883 | cgrp->subsys[ss->subsys_id] = css; | |
48ddbe19 TH |
3884 | |
3885 | /* | |
3886 | * If !clear_css_refs, css holds an extra ref to @cgrp->dentry | |
3887 | * which is put on the last css_put(). dput() requires process | |
3888 | * context, which css_put() may be called without. @css->dput_work | |
3889 | * will be used to invoke dput() asynchronously from css_put(). | |
3890 | */ | |
3891 | INIT_WORK(&css->dput_work, css_dput_fn); | |
3892 | if (ss->__DEPRECATED_clear_css_refs) | |
3893 | set_bit(CSS_CLEAR_CSS_REFS, &css->flags); | |
ddbcc7e8 PM |
3894 | } |
3895 | ||
999cd8a4 PM |
3896 | static void cgroup_lock_hierarchy(struct cgroupfs_root *root) |
3897 | { | |
3898 | /* We need to take each hierarchy_mutex in a consistent order */ | |
3899 | int i; | |
3900 | ||
aae8aab4 BB |
3901 | /* |
3902 | * No worry about a race with rebind_subsystems that might mess up the | |
3903 | * locking order, since both parties are under cgroup_mutex. | |
3904 | */ | |
999cd8a4 PM |
3905 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
3906 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
3907 | if (ss == NULL) |
3908 | continue; | |
999cd8a4 | 3909 | if (ss->root == root) |
cfebe563 | 3910 | mutex_lock(&ss->hierarchy_mutex); |
999cd8a4 PM |
3911 | } |
3912 | } | |
3913 | ||
3914 | static void cgroup_unlock_hierarchy(struct cgroupfs_root *root) | |
3915 | { | |
3916 | int i; | |
3917 | ||
3918 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
3919 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
3920 | if (ss == NULL) |
3921 | continue; | |
999cd8a4 PM |
3922 | if (ss->root == root) |
3923 | mutex_unlock(&ss->hierarchy_mutex); | |
3924 | } | |
3925 | } | |
3926 | ||
ddbcc7e8 | 3927 | /* |
a043e3b2 LZ |
3928 | * cgroup_create - create a cgroup |
3929 | * @parent: cgroup that will be parent of the new cgroup | |
3930 | * @dentry: dentry of the new cgroup | |
3931 | * @mode: mode to set on new inode | |
ddbcc7e8 | 3932 | * |
a043e3b2 | 3933 | * Must be called with the mutex on the parent inode held |
ddbcc7e8 | 3934 | */ |
ddbcc7e8 | 3935 | static long cgroup_create(struct cgroup *parent, struct dentry *dentry, |
a5e7ed32 | 3936 | umode_t mode) |
ddbcc7e8 | 3937 | { |
bd89aabc | 3938 | struct cgroup *cgrp; |
ddbcc7e8 PM |
3939 | struct cgroupfs_root *root = parent->root; |
3940 | int err = 0; | |
3941 | struct cgroup_subsys *ss; | |
3942 | struct super_block *sb = root->sb; | |
3943 | ||
bd89aabc PM |
3944 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
3945 | if (!cgrp) | |
ddbcc7e8 PM |
3946 | return -ENOMEM; |
3947 | ||
3948 | /* Grab a reference on the superblock so the hierarchy doesn't | |
3949 | * get deleted on unmount if there are child cgroups. This | |
3950 | * can be done outside cgroup_mutex, since the sb can't | |
3951 | * disappear while someone has an open control file on the | |
3952 | * fs */ | |
3953 | atomic_inc(&sb->s_active); | |
3954 | ||
3955 | mutex_lock(&cgroup_mutex); | |
3956 | ||
cc31edce | 3957 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 3958 | |
bd89aabc PM |
3959 | cgrp->parent = parent; |
3960 | cgrp->root = parent->root; | |
3961 | cgrp->top_cgroup = parent->top_cgroup; | |
ddbcc7e8 | 3962 | |
b6abdb0e LZ |
3963 | if (notify_on_release(parent)) |
3964 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3965 | ||
97978e6d DL |
3966 | if (clone_children(parent)) |
3967 | set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3968 | ||
ddbcc7e8 | 3969 | for_each_subsys(root, ss) { |
761b3ef5 | 3970 | struct cgroup_subsys_state *css = ss->create(cgrp); |
4528fd05 | 3971 | |
ddbcc7e8 PM |
3972 | if (IS_ERR(css)) { |
3973 | err = PTR_ERR(css); | |
3974 | goto err_destroy; | |
3975 | } | |
bd89aabc | 3976 | init_cgroup_css(css, ss, cgrp); |
4528fd05 LZ |
3977 | if (ss->use_id) { |
3978 | err = alloc_css_id(ss, parent, cgrp); | |
3979 | if (err) | |
38460b48 | 3980 | goto err_destroy; |
4528fd05 | 3981 | } |
38460b48 | 3982 | /* At error, ->destroy() callback has to free assigned ID. */ |
97978e6d | 3983 | if (clone_children(parent) && ss->post_clone) |
761b3ef5 | 3984 | ss->post_clone(cgrp); |
ddbcc7e8 PM |
3985 | } |
3986 | ||
999cd8a4 | 3987 | cgroup_lock_hierarchy(root); |
bd89aabc | 3988 | list_add(&cgrp->sibling, &cgrp->parent->children); |
999cd8a4 | 3989 | cgroup_unlock_hierarchy(root); |
ddbcc7e8 PM |
3990 | root->number_of_cgroups++; |
3991 | ||
bd89aabc | 3992 | err = cgroup_create_dir(cgrp, dentry, mode); |
ddbcc7e8 PM |
3993 | if (err < 0) |
3994 | goto err_remove; | |
3995 | ||
48ddbe19 TH |
3996 | /* If !clear_css_refs, each css holds a ref to the cgroup's dentry */ |
3997 | for_each_subsys(root, ss) | |
3998 | if (!ss->__DEPRECATED_clear_css_refs) | |
3999 | dget(dentry); | |
4000 | ||
ddbcc7e8 | 4001 | /* The cgroup directory was pre-locked for us */ |
bd89aabc | 4002 | BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); |
ddbcc7e8 | 4003 | |
b0ca5a84 TH |
4004 | list_add_tail(&cgrp->allcg_node, &root->allcg_list); |
4005 | ||
bd89aabc | 4006 | err = cgroup_populate_dir(cgrp); |
ddbcc7e8 PM |
4007 | /* If err < 0, we have a half-filled directory - oh well ;) */ |
4008 | ||
4009 | mutex_unlock(&cgroup_mutex); | |
bd89aabc | 4010 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
4011 | |
4012 | return 0; | |
4013 | ||
4014 | err_remove: | |
4015 | ||
baef99a0 | 4016 | cgroup_lock_hierarchy(root); |
bd89aabc | 4017 | list_del(&cgrp->sibling); |
baef99a0 | 4018 | cgroup_unlock_hierarchy(root); |
ddbcc7e8 PM |
4019 | root->number_of_cgroups--; |
4020 | ||
4021 | err_destroy: | |
4022 | ||
4023 | for_each_subsys(root, ss) { | |
bd89aabc | 4024 | if (cgrp->subsys[ss->subsys_id]) |
761b3ef5 | 4025 | ss->destroy(cgrp); |
ddbcc7e8 PM |
4026 | } |
4027 | ||
4028 | mutex_unlock(&cgroup_mutex); | |
4029 | ||
4030 | /* Release the reference count that we took on the superblock */ | |
4031 | deactivate_super(sb); | |
4032 | ||
bd89aabc | 4033 | kfree(cgrp); |
ddbcc7e8 PM |
4034 | return err; |
4035 | } | |
4036 | ||
18bb1db3 | 4037 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
ddbcc7e8 PM |
4038 | { |
4039 | struct cgroup *c_parent = dentry->d_parent->d_fsdata; | |
4040 | ||
4041 | /* the vfs holds inode->i_mutex already */ | |
4042 | return cgroup_create(c_parent, dentry, mode | S_IFDIR); | |
4043 | } | |
4044 | ||
28b4c27b TH |
4045 | /* |
4046 | * Check the reference count on each subsystem. Since we already | |
4047 | * established that there are no tasks in the cgroup, if the css refcount | |
4048 | * is also 1, then there should be no outstanding references, so the | |
4049 | * subsystem is safe to destroy. We scan across all subsystems rather than | |
4050 | * using the per-hierarchy linked list of mounted subsystems since we can | |
4051 | * be called via check_for_release() with no synchronization other than | |
4052 | * RCU, and the subsystem linked list isn't RCU-safe. | |
4053 | */ | |
55b6fd01 | 4054 | static int cgroup_has_css_refs(struct cgroup *cgrp) |
81a6a5cd | 4055 | { |
81a6a5cd | 4056 | int i; |
28b4c27b | 4057 | |
aae8aab4 BB |
4058 | /* |
4059 | * We won't need to lock the subsys array, because the subsystems | |
4060 | * we're concerned about aren't going anywhere since our cgroup root | |
4061 | * has a reference on them. | |
4062 | */ | |
81a6a5cd PM |
4063 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
4064 | struct cgroup_subsys *ss = subsys[i]; | |
4065 | struct cgroup_subsys_state *css; | |
28b4c27b | 4066 | |
aae8aab4 BB |
4067 | /* Skip subsystems not present or not in this hierarchy */ |
4068 | if (ss == NULL || ss->root != cgrp->root) | |
81a6a5cd | 4069 | continue; |
28b4c27b | 4070 | |
bd89aabc | 4071 | css = cgrp->subsys[ss->subsys_id]; |
28b4c27b TH |
4072 | /* |
4073 | * When called from check_for_release() it's possible | |
81a6a5cd PM |
4074 | * that by this point the cgroup has been removed |
4075 | * and the css deleted. But a false-positive doesn't | |
4076 | * matter, since it can only happen if the cgroup | |
4077 | * has been deleted and hence no longer needs the | |
28b4c27b TH |
4078 | * release agent to be called anyway. |
4079 | */ | |
4080 | if (css && css_refcnt(css) > 1) | |
81a6a5cd | 4081 | return 1; |
81a6a5cd PM |
4082 | } |
4083 | return 0; | |
4084 | } | |
4085 | ||
e7c5ec91 PM |
4086 | /* |
4087 | * Atomically mark all (or else none) of the cgroup's CSS objects as | |
4088 | * CSS_REMOVED. Return true on success, or false if the cgroup has | |
4089 | * busy subsystems. Call with cgroup_mutex held | |
48ddbe19 TH |
4090 | * |
4091 | * Depending on whether a subsys has __DEPRECATED_clear_css_refs set or | |
4092 | * not, cgroup removal behaves differently. | |
4093 | * | |
4094 | * If clear is set, css refcnt for the subsystem should be zero before | |
4095 | * cgroup removal can be committed. This is implemented by | |
4096 | * CGRP_WAIT_ON_RMDIR and retry logic around ->pre_destroy(), which may be | |
4097 | * called multiple times until all css refcnts reach zero and is allowed to | |
4098 | * veto removal on any invocation. This behavior is deprecated and will be | |
4099 | * removed as soon as the existing user (memcg) is updated. | |
4100 | * | |
4101 | * If clear is not set, each css holds an extra reference to the cgroup's | |
4102 | * dentry and cgroup removal proceeds regardless of css refs. | |
4103 | * ->pre_destroy() will be called at least once and is not allowed to fail. | |
4104 | * On the last put of each css, whenever that may be, the extra dentry ref | |
4105 | * is put so that dentry destruction happens only after all css's are | |
4106 | * released. | |
e7c5ec91 | 4107 | */ |
e7c5ec91 PM |
4108 | static int cgroup_clear_css_refs(struct cgroup *cgrp) |
4109 | { | |
4110 | struct cgroup_subsys *ss; | |
4111 | unsigned long flags; | |
4112 | bool failed = false; | |
28b4c27b | 4113 | |
e7c5ec91 | 4114 | local_irq_save(flags); |
28b4c27b TH |
4115 | |
4116 | /* | |
4117 | * Block new css_tryget() by deactivating refcnt. If all refcnts | |
48ddbe19 TH |
4118 | * for subsystems w/ clear_css_refs set were 1 at the moment of |
4119 | * deactivation, we succeeded. | |
28b4c27b | 4120 | */ |
e7c5ec91 PM |
4121 | for_each_subsys(cgrp->root, ss) { |
4122 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
28b4c27b TH |
4123 | |
4124 | WARN_ON(atomic_read(&css->refcnt) < 0); | |
4125 | atomic_add(CSS_DEACT_BIAS, &css->refcnt); | |
48ddbe19 TH |
4126 | |
4127 | if (ss->__DEPRECATED_clear_css_refs) | |
4128 | failed |= css_refcnt(css) != 1; | |
e7c5ec91 | 4129 | } |
28b4c27b TH |
4130 | |
4131 | /* | |
4132 | * If succeeded, set REMOVED and put all the base refs; otherwise, | |
4133 | * restore refcnts to positive values. Either way, all in-progress | |
4134 | * css_tryget() will be released. | |
4135 | */ | |
e7c5ec91 PM |
4136 | for_each_subsys(cgrp->root, ss) { |
4137 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
28b4c27b TH |
4138 | |
4139 | if (!failed) { | |
e7c5ec91 | 4140 | set_bit(CSS_REMOVED, &css->flags); |
28b4c27b TH |
4141 | css_put(css); |
4142 | } else { | |
4143 | atomic_sub(CSS_DEACT_BIAS, &css->refcnt); | |
e7c5ec91 PM |
4144 | } |
4145 | } | |
28b4c27b | 4146 | |
e7c5ec91 PM |
4147 | local_irq_restore(flags); |
4148 | return !failed; | |
4149 | } | |
4150 | ||
ddbcc7e8 PM |
4151 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) |
4152 | { | |
bd89aabc | 4153 | struct cgroup *cgrp = dentry->d_fsdata; |
ddbcc7e8 PM |
4154 | struct dentry *d; |
4155 | struct cgroup *parent; | |
ec64f515 | 4156 | DEFINE_WAIT(wait); |
4ab78683 | 4157 | struct cgroup_event *event, *tmp; |
ec64f515 | 4158 | int ret; |
ddbcc7e8 PM |
4159 | |
4160 | /* the vfs holds both inode->i_mutex already */ | |
ec64f515 | 4161 | again: |
ddbcc7e8 | 4162 | mutex_lock(&cgroup_mutex); |
bd89aabc | 4163 | if (atomic_read(&cgrp->count) != 0) { |
ddbcc7e8 PM |
4164 | mutex_unlock(&cgroup_mutex); |
4165 | return -EBUSY; | |
4166 | } | |
bd89aabc | 4167 | if (!list_empty(&cgrp->children)) { |
ddbcc7e8 PM |
4168 | mutex_unlock(&cgroup_mutex); |
4169 | return -EBUSY; | |
4170 | } | |
3fa59dfb | 4171 | mutex_unlock(&cgroup_mutex); |
a043e3b2 | 4172 | |
88703267 KH |
4173 | /* |
4174 | * In general, subsystem has no css->refcnt after pre_destroy(). But | |
4175 | * in racy cases, subsystem may have to get css->refcnt after | |
4176 | * pre_destroy() and it makes rmdir return with -EBUSY. This sometimes | |
4177 | * make rmdir return -EBUSY too often. To avoid that, we use waitqueue | |
4178 | * for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir | |
4179 | * and subsystem's reference count handling. Please see css_get/put | |
4180 | * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation. | |
4181 | */ | |
4182 | set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
4183 | ||
4fca88c8 | 4184 | /* |
a043e3b2 LZ |
4185 | * Call pre_destroy handlers of subsys. Notify subsystems |
4186 | * that rmdir() request comes. | |
4fca88c8 | 4187 | */ |
ec64f515 | 4188 | ret = cgroup_call_pre_destroy(cgrp); |
88703267 KH |
4189 | if (ret) { |
4190 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
ec64f515 | 4191 | return ret; |
88703267 | 4192 | } |
ddbcc7e8 | 4193 | |
3fa59dfb KH |
4194 | mutex_lock(&cgroup_mutex); |
4195 | parent = cgrp->parent; | |
ec64f515 | 4196 | if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) { |
88703267 | 4197 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); |
ddbcc7e8 PM |
4198 | mutex_unlock(&cgroup_mutex); |
4199 | return -EBUSY; | |
4200 | } | |
ec64f515 | 4201 | prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE); |
ec64f515 KH |
4202 | if (!cgroup_clear_css_refs(cgrp)) { |
4203 | mutex_unlock(&cgroup_mutex); | |
88703267 KH |
4204 | /* |
4205 | * Because someone may call cgroup_wakeup_rmdir_waiter() before | |
4206 | * prepare_to_wait(), we need to check this flag. | |
4207 | */ | |
4208 | if (test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)) | |
4209 | schedule(); | |
ec64f515 KH |
4210 | finish_wait(&cgroup_rmdir_waitq, &wait); |
4211 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
4212 | if (signal_pending(current)) | |
4213 | return -EINTR; | |
4214 | goto again; | |
4215 | } | |
4216 | /* NO css_tryget() can success after here. */ | |
4217 | finish_wait(&cgroup_rmdir_waitq, &wait); | |
4218 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
ddbcc7e8 | 4219 | |
cdcc136f | 4220 | raw_spin_lock(&release_list_lock); |
bd89aabc PM |
4221 | set_bit(CGRP_REMOVED, &cgrp->flags); |
4222 | if (!list_empty(&cgrp->release_list)) | |
8d258797 | 4223 | list_del_init(&cgrp->release_list); |
cdcc136f | 4224 | raw_spin_unlock(&release_list_lock); |
999cd8a4 PM |
4225 | |
4226 | cgroup_lock_hierarchy(cgrp->root); | |
4227 | /* delete this cgroup from parent->children */ | |
8d258797 | 4228 | list_del_init(&cgrp->sibling); |
999cd8a4 PM |
4229 | cgroup_unlock_hierarchy(cgrp->root); |
4230 | ||
b0ca5a84 TH |
4231 | list_del_init(&cgrp->allcg_node); |
4232 | ||
bd89aabc | 4233 | d = dget(cgrp->dentry); |
ddbcc7e8 PM |
4234 | |
4235 | cgroup_d_remove_dir(d); | |
4236 | dput(d); | |
ddbcc7e8 | 4237 | |
bd89aabc | 4238 | set_bit(CGRP_RELEASABLE, &parent->flags); |
81a6a5cd PM |
4239 | check_for_release(parent); |
4240 | ||
4ab78683 KS |
4241 | /* |
4242 | * Unregister events and notify userspace. | |
4243 | * Notify userspace about cgroup removing only after rmdir of cgroup | |
4244 | * directory to avoid race between userspace and kernelspace | |
4245 | */ | |
4246 | spin_lock(&cgrp->event_list_lock); | |
4247 | list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { | |
4248 | list_del(&event->list); | |
4249 | remove_wait_queue(event->wqh, &event->wait); | |
4250 | eventfd_signal(event->eventfd, 1); | |
4251 | schedule_work(&event->remove); | |
4252 | } | |
4253 | spin_unlock(&cgrp->event_list_lock); | |
4254 | ||
ddbcc7e8 | 4255 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
4256 | return 0; |
4257 | } | |
4258 | ||
8e3f6541 TH |
4259 | static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss) |
4260 | { | |
4261 | INIT_LIST_HEAD(&ss->cftsets); | |
4262 | ||
4263 | /* | |
4264 | * base_cftset is embedded in subsys itself, no need to worry about | |
4265 | * deregistration. | |
4266 | */ | |
4267 | if (ss->base_cftypes) { | |
4268 | ss->base_cftset.cfts = ss->base_cftypes; | |
4269 | list_add_tail(&ss->base_cftset.node, &ss->cftsets); | |
4270 | } | |
4271 | } | |
4272 | ||
06a11920 | 4273 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
ddbcc7e8 | 4274 | { |
ddbcc7e8 | 4275 | struct cgroup_subsys_state *css; |
cfe36bde DC |
4276 | |
4277 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 4278 | |
8e3f6541 TH |
4279 | /* init base cftset */ |
4280 | cgroup_init_cftsets(ss); | |
4281 | ||
ddbcc7e8 | 4282 | /* Create the top cgroup state for this subsystem */ |
33a68ac1 | 4283 | list_add(&ss->sibling, &rootnode.subsys_list); |
ddbcc7e8 | 4284 | ss->root = &rootnode; |
761b3ef5 | 4285 | css = ss->create(dummytop); |
ddbcc7e8 PM |
4286 | /* We don't handle early failures gracefully */ |
4287 | BUG_ON(IS_ERR(css)); | |
4288 | init_cgroup_css(css, ss, dummytop); | |
4289 | ||
e8d55fde | 4290 | /* Update the init_css_set to contain a subsys |
817929ec | 4291 | * pointer to this state - since the subsystem is |
e8d55fde LZ |
4292 | * newly registered, all tasks and hence the |
4293 | * init_css_set is in the subsystem's top cgroup. */ | |
4294 | init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id]; | |
ddbcc7e8 PM |
4295 | |
4296 | need_forkexit_callback |= ss->fork || ss->exit; | |
4297 | ||
e8d55fde LZ |
4298 | /* At system boot, before all subsystems have been |
4299 | * registered, no tasks have been forked, so we don't | |
4300 | * need to invoke fork callbacks here. */ | |
4301 | BUG_ON(!list_empty(&init_task.tasks)); | |
4302 | ||
999cd8a4 | 4303 | mutex_init(&ss->hierarchy_mutex); |
cfebe563 | 4304 | lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); |
ddbcc7e8 | 4305 | ss->active = 1; |
e6a1105b BB |
4306 | |
4307 | /* this function shouldn't be used with modular subsystems, since they | |
4308 | * need to register a subsys_id, among other things */ | |
4309 | BUG_ON(ss->module); | |
4310 | } | |
4311 | ||
4312 | /** | |
4313 | * cgroup_load_subsys: load and register a modular subsystem at runtime | |
4314 | * @ss: the subsystem to load | |
4315 | * | |
4316 | * This function should be called in a modular subsystem's initcall. If the | |
88393161 | 4317 | * subsystem is built as a module, it will be assigned a new subsys_id and set |
e6a1105b BB |
4318 | * up for use. If the subsystem is built-in anyway, work is delegated to the |
4319 | * simpler cgroup_init_subsys. | |
4320 | */ | |
4321 | int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) | |
4322 | { | |
4323 | int i; | |
4324 | struct cgroup_subsys_state *css; | |
4325 | ||
4326 | /* check name and function validity */ | |
4327 | if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || | |
4328 | ss->create == NULL || ss->destroy == NULL) | |
4329 | return -EINVAL; | |
4330 | ||
4331 | /* | |
4332 | * we don't support callbacks in modular subsystems. this check is | |
4333 | * before the ss->module check for consistency; a subsystem that could | |
4334 | * be a module should still have no callbacks even if the user isn't | |
4335 | * compiling it as one. | |
4336 | */ | |
4337 | if (ss->fork || ss->exit) | |
4338 | return -EINVAL; | |
4339 | ||
4340 | /* | |
4341 | * an optionally modular subsystem is built-in: we want to do nothing, | |
4342 | * since cgroup_init_subsys will have already taken care of it. | |
4343 | */ | |
4344 | if (ss->module == NULL) { | |
4345 | /* a few sanity checks */ | |
4346 | BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT); | |
4347 | BUG_ON(subsys[ss->subsys_id] != ss); | |
4348 | return 0; | |
4349 | } | |
4350 | ||
8e3f6541 TH |
4351 | /* init base cftset */ |
4352 | cgroup_init_cftsets(ss); | |
4353 | ||
e6a1105b BB |
4354 | /* |
4355 | * need to register a subsys id before anything else - for example, | |
4356 | * init_cgroup_css needs it. | |
4357 | */ | |
4358 | mutex_lock(&cgroup_mutex); | |
4359 | /* find the first empty slot in the array */ | |
4360 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { | |
4361 | if (subsys[i] == NULL) | |
4362 | break; | |
4363 | } | |
4364 | if (i == CGROUP_SUBSYS_COUNT) { | |
4365 | /* maximum number of subsystems already registered! */ | |
4366 | mutex_unlock(&cgroup_mutex); | |
4367 | return -EBUSY; | |
4368 | } | |
4369 | /* assign ourselves the subsys_id */ | |
4370 | ss->subsys_id = i; | |
4371 | subsys[i] = ss; | |
4372 | ||
4373 | /* | |
4374 | * no ss->create seems to need anything important in the ss struct, so | |
4375 | * this can happen first (i.e. before the rootnode attachment). | |
4376 | */ | |
761b3ef5 | 4377 | css = ss->create(dummytop); |
e6a1105b BB |
4378 | if (IS_ERR(css)) { |
4379 | /* failure case - need to deassign the subsys[] slot. */ | |
4380 | subsys[i] = NULL; | |
4381 | mutex_unlock(&cgroup_mutex); | |
4382 | return PTR_ERR(css); | |
4383 | } | |
4384 | ||
4385 | list_add(&ss->sibling, &rootnode.subsys_list); | |
4386 | ss->root = &rootnode; | |
4387 | ||
4388 | /* our new subsystem will be attached to the dummy hierarchy. */ | |
4389 | init_cgroup_css(css, ss, dummytop); | |
4390 | /* init_idr must be after init_cgroup_css because it sets css->id. */ | |
4391 | if (ss->use_id) { | |
4392 | int ret = cgroup_init_idr(ss, css); | |
4393 | if (ret) { | |
4394 | dummytop->subsys[ss->subsys_id] = NULL; | |
761b3ef5 | 4395 | ss->destroy(dummytop); |
e6a1105b BB |
4396 | subsys[i] = NULL; |
4397 | mutex_unlock(&cgroup_mutex); | |
4398 | return ret; | |
4399 | } | |
4400 | } | |
4401 | ||
4402 | /* | |
4403 | * Now we need to entangle the css into the existing css_sets. unlike | |
4404 | * in cgroup_init_subsys, there are now multiple css_sets, so each one | |
4405 | * will need a new pointer to it; done by iterating the css_set_table. | |
4406 | * furthermore, modifying the existing css_sets will corrupt the hash | |
4407 | * table state, so each changed css_set will need its hash recomputed. | |
4408 | * this is all done under the css_set_lock. | |
4409 | */ | |
4410 | write_lock(&css_set_lock); | |
4411 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { | |
4412 | struct css_set *cg; | |
4413 | struct hlist_node *node, *tmp; | |
4414 | struct hlist_head *bucket = &css_set_table[i], *new_bucket; | |
4415 | ||
4416 | hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) { | |
4417 | /* skip entries that we already rehashed */ | |
4418 | if (cg->subsys[ss->subsys_id]) | |
4419 | continue; | |
4420 | /* remove existing entry */ | |
4421 | hlist_del(&cg->hlist); | |
4422 | /* set new value */ | |
4423 | cg->subsys[ss->subsys_id] = css; | |
4424 | /* recompute hash and restore entry */ | |
4425 | new_bucket = css_set_hash(cg->subsys); | |
4426 | hlist_add_head(&cg->hlist, new_bucket); | |
4427 | } | |
4428 | } | |
4429 | write_unlock(&css_set_lock); | |
4430 | ||
4431 | mutex_init(&ss->hierarchy_mutex); | |
4432 | lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); | |
4433 | ss->active = 1; | |
4434 | ||
e6a1105b BB |
4435 | /* success! */ |
4436 | mutex_unlock(&cgroup_mutex); | |
4437 | return 0; | |
ddbcc7e8 | 4438 | } |
e6a1105b | 4439 | EXPORT_SYMBOL_GPL(cgroup_load_subsys); |
ddbcc7e8 | 4440 | |
cf5d5941 BB |
4441 | /** |
4442 | * cgroup_unload_subsys: unload a modular subsystem | |
4443 | * @ss: the subsystem to unload | |
4444 | * | |
4445 | * This function should be called in a modular subsystem's exitcall. When this | |
4446 | * function is invoked, the refcount on the subsystem's module will be 0, so | |
4447 | * the subsystem will not be attached to any hierarchy. | |
4448 | */ | |
4449 | void cgroup_unload_subsys(struct cgroup_subsys *ss) | |
4450 | { | |
4451 | struct cg_cgroup_link *link; | |
4452 | struct hlist_head *hhead; | |
4453 | ||
4454 | BUG_ON(ss->module == NULL); | |
4455 | ||
4456 | /* | |
4457 | * we shouldn't be called if the subsystem is in use, and the use of | |
4458 | * try_module_get in parse_cgroupfs_options should ensure that it | |
4459 | * doesn't start being used while we're killing it off. | |
4460 | */ | |
4461 | BUG_ON(ss->root != &rootnode); | |
4462 | ||
4463 | mutex_lock(&cgroup_mutex); | |
4464 | /* deassign the subsys_id */ | |
4465 | BUG_ON(ss->subsys_id < CGROUP_BUILTIN_SUBSYS_COUNT); | |
4466 | subsys[ss->subsys_id] = NULL; | |
4467 | ||
4468 | /* remove subsystem from rootnode's list of subsystems */ | |
8d258797 | 4469 | list_del_init(&ss->sibling); |
cf5d5941 BB |
4470 | |
4471 | /* | |
4472 | * disentangle the css from all css_sets attached to the dummytop. as | |
4473 | * in loading, we need to pay our respects to the hashtable gods. | |
4474 | */ | |
4475 | write_lock(&css_set_lock); | |
4476 | list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) { | |
4477 | struct css_set *cg = link->cg; | |
4478 | ||
4479 | hlist_del(&cg->hlist); | |
4480 | BUG_ON(!cg->subsys[ss->subsys_id]); | |
4481 | cg->subsys[ss->subsys_id] = NULL; | |
4482 | hhead = css_set_hash(cg->subsys); | |
4483 | hlist_add_head(&cg->hlist, hhead); | |
4484 | } | |
4485 | write_unlock(&css_set_lock); | |
4486 | ||
4487 | /* | |
4488 | * remove subsystem's css from the dummytop and free it - need to free | |
4489 | * before marking as null because ss->destroy needs the cgrp->subsys | |
4490 | * pointer to find their state. note that this also takes care of | |
4491 | * freeing the css_id. | |
4492 | */ | |
761b3ef5 | 4493 | ss->destroy(dummytop); |
cf5d5941 BB |
4494 | dummytop->subsys[ss->subsys_id] = NULL; |
4495 | ||
4496 | mutex_unlock(&cgroup_mutex); | |
4497 | } | |
4498 | EXPORT_SYMBOL_GPL(cgroup_unload_subsys); | |
4499 | ||
ddbcc7e8 | 4500 | /** |
a043e3b2 LZ |
4501 | * cgroup_init_early - cgroup initialization at system boot |
4502 | * | |
4503 | * Initialize cgroups at system boot, and initialize any | |
4504 | * subsystems that request early init. | |
ddbcc7e8 PM |
4505 | */ |
4506 | int __init cgroup_init_early(void) | |
4507 | { | |
4508 | int i; | |
146aa1bd | 4509 | atomic_set(&init_css_set.refcount, 1); |
817929ec PM |
4510 | INIT_LIST_HEAD(&init_css_set.cg_links); |
4511 | INIT_LIST_HEAD(&init_css_set.tasks); | |
472b1053 | 4512 | INIT_HLIST_NODE(&init_css_set.hlist); |
817929ec | 4513 | css_set_count = 1; |
ddbcc7e8 | 4514 | init_cgroup_root(&rootnode); |
817929ec PM |
4515 | root_count = 1; |
4516 | init_task.cgroups = &init_css_set; | |
4517 | ||
4518 | init_css_set_link.cg = &init_css_set; | |
7717f7ba | 4519 | init_css_set_link.cgrp = dummytop; |
bd89aabc | 4520 | list_add(&init_css_set_link.cgrp_link_list, |
817929ec PM |
4521 | &rootnode.top_cgroup.css_sets); |
4522 | list_add(&init_css_set_link.cg_link_list, | |
4523 | &init_css_set.cg_links); | |
ddbcc7e8 | 4524 | |
472b1053 LZ |
4525 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) |
4526 | INIT_HLIST_HEAD(&css_set_table[i]); | |
4527 | ||
aae8aab4 BB |
4528 | /* at bootup time, we don't worry about modular subsystems */ |
4529 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
ddbcc7e8 PM |
4530 | struct cgroup_subsys *ss = subsys[i]; |
4531 | ||
4532 | BUG_ON(!ss->name); | |
4533 | BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); | |
4534 | BUG_ON(!ss->create); | |
4535 | BUG_ON(!ss->destroy); | |
4536 | if (ss->subsys_id != i) { | |
cfe36bde | 4537 | printk(KERN_ERR "cgroup: Subsys %s id == %d\n", |
ddbcc7e8 PM |
4538 | ss->name, ss->subsys_id); |
4539 | BUG(); | |
4540 | } | |
4541 | ||
4542 | if (ss->early_init) | |
4543 | cgroup_init_subsys(ss); | |
4544 | } | |
4545 | return 0; | |
4546 | } | |
4547 | ||
4548 | /** | |
a043e3b2 LZ |
4549 | * cgroup_init - cgroup initialization |
4550 | * | |
4551 | * Register cgroup filesystem and /proc file, and initialize | |
4552 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
4553 | */ |
4554 | int __init cgroup_init(void) | |
4555 | { | |
4556 | int err; | |
4557 | int i; | |
472b1053 | 4558 | struct hlist_head *hhead; |
a424316c PM |
4559 | |
4560 | err = bdi_init(&cgroup_backing_dev_info); | |
4561 | if (err) | |
4562 | return err; | |
ddbcc7e8 | 4563 | |
aae8aab4 BB |
4564 | /* at bootup time, we don't worry about modular subsystems */ |
4565 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
ddbcc7e8 PM |
4566 | struct cgroup_subsys *ss = subsys[i]; |
4567 | if (!ss->early_init) | |
4568 | cgroup_init_subsys(ss); | |
38460b48 | 4569 | if (ss->use_id) |
e6a1105b | 4570 | cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]); |
ddbcc7e8 PM |
4571 | } |
4572 | ||
472b1053 LZ |
4573 | /* Add init_css_set to the hash table */ |
4574 | hhead = css_set_hash(init_css_set.subsys); | |
4575 | hlist_add_head(&init_css_set.hlist, hhead); | |
2c6ab6d2 | 4576 | BUG_ON(!init_root_id(&rootnode)); |
676db4af GKH |
4577 | |
4578 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); | |
4579 | if (!cgroup_kobj) { | |
4580 | err = -ENOMEM; | |
4581 | goto out; | |
4582 | } | |
4583 | ||
ddbcc7e8 | 4584 | err = register_filesystem(&cgroup_fs_type); |
676db4af GKH |
4585 | if (err < 0) { |
4586 | kobject_put(cgroup_kobj); | |
ddbcc7e8 | 4587 | goto out; |
676db4af | 4588 | } |
ddbcc7e8 | 4589 | |
46ae220b | 4590 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
a424316c | 4591 | |
ddbcc7e8 | 4592 | out: |
a424316c PM |
4593 | if (err) |
4594 | bdi_destroy(&cgroup_backing_dev_info); | |
4595 | ||
ddbcc7e8 PM |
4596 | return err; |
4597 | } | |
b4f48b63 | 4598 | |
a424316c PM |
4599 | /* |
4600 | * proc_cgroup_show() | |
4601 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
4602 | * - Used for /proc/<pid>/cgroup. | |
4603 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it | |
4604 | * doesn't really matter if tsk->cgroup changes after we read it, | |
956db3ca | 4605 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it |
a424316c PM |
4606 | * anyway. No need to check that tsk->cgroup != NULL, thanks to |
4607 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks | |
4608 | * cgroup to top_cgroup. | |
4609 | */ | |
4610 | ||
4611 | /* TODO: Use a proper seq_file iterator */ | |
4612 | static int proc_cgroup_show(struct seq_file *m, void *v) | |
4613 | { | |
4614 | struct pid *pid; | |
4615 | struct task_struct *tsk; | |
4616 | char *buf; | |
4617 | int retval; | |
4618 | struct cgroupfs_root *root; | |
4619 | ||
4620 | retval = -ENOMEM; | |
4621 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
4622 | if (!buf) | |
4623 | goto out; | |
4624 | ||
4625 | retval = -ESRCH; | |
4626 | pid = m->private; | |
4627 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
4628 | if (!tsk) | |
4629 | goto out_free; | |
4630 | ||
4631 | retval = 0; | |
4632 | ||
4633 | mutex_lock(&cgroup_mutex); | |
4634 | ||
e5f6a860 | 4635 | for_each_active_root(root) { |
a424316c | 4636 | struct cgroup_subsys *ss; |
bd89aabc | 4637 | struct cgroup *cgrp; |
a424316c PM |
4638 | int count = 0; |
4639 | ||
2c6ab6d2 | 4640 | seq_printf(m, "%d:", root->hierarchy_id); |
a424316c PM |
4641 | for_each_subsys(root, ss) |
4642 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); | |
c6d57f33 PM |
4643 | if (strlen(root->name)) |
4644 | seq_printf(m, "%sname=%s", count ? "," : "", | |
4645 | root->name); | |
a424316c | 4646 | seq_putc(m, ':'); |
7717f7ba | 4647 | cgrp = task_cgroup_from_root(tsk, root); |
bd89aabc | 4648 | retval = cgroup_path(cgrp, buf, PAGE_SIZE); |
a424316c PM |
4649 | if (retval < 0) |
4650 | goto out_unlock; | |
4651 | seq_puts(m, buf); | |
4652 | seq_putc(m, '\n'); | |
4653 | } | |
4654 | ||
4655 | out_unlock: | |
4656 | mutex_unlock(&cgroup_mutex); | |
4657 | put_task_struct(tsk); | |
4658 | out_free: | |
4659 | kfree(buf); | |
4660 | out: | |
4661 | return retval; | |
4662 | } | |
4663 | ||
4664 | static int cgroup_open(struct inode *inode, struct file *file) | |
4665 | { | |
4666 | struct pid *pid = PROC_I(inode)->pid; | |
4667 | return single_open(file, proc_cgroup_show, pid); | |
4668 | } | |
4669 | ||
828c0950 | 4670 | const struct file_operations proc_cgroup_operations = { |
a424316c PM |
4671 | .open = cgroup_open, |
4672 | .read = seq_read, | |
4673 | .llseek = seq_lseek, | |
4674 | .release = single_release, | |
4675 | }; | |
4676 | ||
4677 | /* Display information about each subsystem and each hierarchy */ | |
4678 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
4679 | { | |
4680 | int i; | |
a424316c | 4681 | |
8bab8dde | 4682 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
4683 | /* |
4684 | * ideally we don't want subsystems moving around while we do this. | |
4685 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
4686 | * subsys/hierarchy state. | |
4687 | */ | |
a424316c | 4688 | mutex_lock(&cgroup_mutex); |
a424316c PM |
4689 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
4690 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
4691 | if (ss == NULL) |
4692 | continue; | |
2c6ab6d2 PM |
4693 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
4694 | ss->name, ss->root->hierarchy_id, | |
8bab8dde | 4695 | ss->root->number_of_cgroups, !ss->disabled); |
a424316c PM |
4696 | } |
4697 | mutex_unlock(&cgroup_mutex); | |
4698 | return 0; | |
4699 | } | |
4700 | ||
4701 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
4702 | { | |
9dce07f1 | 4703 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
4704 | } |
4705 | ||
828c0950 | 4706 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
4707 | .open = cgroupstats_open, |
4708 | .read = seq_read, | |
4709 | .llseek = seq_lseek, | |
4710 | .release = single_release, | |
4711 | }; | |
4712 | ||
b4f48b63 PM |
4713 | /** |
4714 | * cgroup_fork - attach newly forked task to its parents cgroup. | |
a043e3b2 | 4715 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 PM |
4716 | * |
4717 | * Description: A task inherits its parent's cgroup at fork(). | |
4718 | * | |
4719 | * A pointer to the shared css_set was automatically copied in | |
4720 | * fork.c by dup_task_struct(). However, we ignore that copy, since | |
7e381b0e FW |
4721 | * it was not made under the protection of RCU, cgroup_mutex or |
4722 | * threadgroup_change_begin(), so it might no longer be a valid | |
4723 | * cgroup pointer. cgroup_attach_task() might have already changed | |
4724 | * current->cgroups, allowing the previously referenced cgroup | |
4725 | * group to be removed and freed. | |
4726 | * | |
4727 | * Outside the pointer validity we also need to process the css_set | |
4728 | * inheritance between threadgoup_change_begin() and | |
4729 | * threadgoup_change_end(), this way there is no leak in any process | |
4730 | * wide migration performed by cgroup_attach_proc() that could otherwise | |
4731 | * miss a thread because it is too early or too late in the fork stage. | |
b4f48b63 PM |
4732 | * |
4733 | * At the point that cgroup_fork() is called, 'current' is the parent | |
4734 | * task, and the passed argument 'child' points to the child task. | |
4735 | */ | |
4736 | void cgroup_fork(struct task_struct *child) | |
4737 | { | |
7e381b0e FW |
4738 | /* |
4739 | * We don't need to task_lock() current because current->cgroups | |
4740 | * can't be changed concurrently here. The parent obviously hasn't | |
4741 | * exited and called cgroup_exit(), and we are synchronized against | |
4742 | * cgroup migration through threadgroup_change_begin(). | |
4743 | */ | |
817929ec PM |
4744 | child->cgroups = current->cgroups; |
4745 | get_css_set(child->cgroups); | |
817929ec | 4746 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
4747 | } |
4748 | ||
4749 | /** | |
a043e3b2 LZ |
4750 | * cgroup_fork_callbacks - run fork callbacks |
4751 | * @child: the new task | |
4752 | * | |
4753 | * Called on a new task very soon before adding it to the | |
4754 | * tasklist. No need to take any locks since no-one can | |
4755 | * be operating on this task. | |
b4f48b63 PM |
4756 | */ |
4757 | void cgroup_fork_callbacks(struct task_struct *child) | |
4758 | { | |
4759 | if (need_forkexit_callback) { | |
4760 | int i; | |
aae8aab4 BB |
4761 | /* |
4762 | * forkexit callbacks are only supported for builtin | |
4763 | * subsystems, and the builtin section of the subsys array is | |
4764 | * immutable, so we don't need to lock the subsys array here. | |
4765 | */ | |
4766 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
b4f48b63 PM |
4767 | struct cgroup_subsys *ss = subsys[i]; |
4768 | if (ss->fork) | |
761b3ef5 | 4769 | ss->fork(child); |
b4f48b63 PM |
4770 | } |
4771 | } | |
4772 | } | |
4773 | ||
817929ec | 4774 | /** |
a043e3b2 LZ |
4775 | * cgroup_post_fork - called on a new task after adding it to the task list |
4776 | * @child: the task in question | |
4777 | * | |
4778 | * Adds the task to the list running through its css_set if necessary. | |
4779 | * Has to be after the task is visible on the task list in case we race | |
4780 | * with the first call to cgroup_iter_start() - to guarantee that the | |
4781 | * new task ends up on its list. | |
4782 | */ | |
817929ec PM |
4783 | void cgroup_post_fork(struct task_struct *child) |
4784 | { | |
3ce3230a FW |
4785 | /* |
4786 | * use_task_css_set_links is set to 1 before we walk the tasklist | |
4787 | * under the tasklist_lock and we read it here after we added the child | |
4788 | * to the tasklist under the tasklist_lock as well. If the child wasn't | |
4789 | * yet in the tasklist when we walked through it from | |
4790 | * cgroup_enable_task_cg_lists(), then use_task_css_set_links value | |
4791 | * should be visible now due to the paired locking and barriers implied | |
4792 | * by LOCK/UNLOCK: it is written before the tasklist_lock unlock | |
4793 | * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock | |
4794 | * lock on fork. | |
4795 | */ | |
817929ec PM |
4796 | if (use_task_css_set_links) { |
4797 | write_lock(&css_set_lock); | |
7e3aa30a FW |
4798 | if (list_empty(&child->cg_list)) { |
4799 | /* | |
4800 | * It's safe to use child->cgroups without task_lock() | |
4801 | * here because we are protected through | |
4802 | * threadgroup_change_begin() against concurrent | |
4803 | * css_set change in cgroup_task_migrate(). Also | |
4804 | * the task can't exit at that point until | |
4805 | * wake_up_new_task() is called, so we are protected | |
4806 | * against cgroup_exit() setting child->cgroup to | |
4807 | * init_css_set. | |
4808 | */ | |
817929ec | 4809 | list_add(&child->cg_list, &child->cgroups->tasks); |
7e3aa30a | 4810 | } |
817929ec PM |
4811 | write_unlock(&css_set_lock); |
4812 | } | |
4813 | } | |
b4f48b63 PM |
4814 | /** |
4815 | * cgroup_exit - detach cgroup from exiting task | |
4816 | * @tsk: pointer to task_struct of exiting process | |
a043e3b2 | 4817 | * @run_callback: run exit callbacks? |
b4f48b63 PM |
4818 | * |
4819 | * Description: Detach cgroup from @tsk and release it. | |
4820 | * | |
4821 | * Note that cgroups marked notify_on_release force every task in | |
4822 | * them to take the global cgroup_mutex mutex when exiting. | |
4823 | * This could impact scaling on very large systems. Be reluctant to | |
4824 | * use notify_on_release cgroups where very high task exit scaling | |
4825 | * is required on large systems. | |
4826 | * | |
4827 | * the_top_cgroup_hack: | |
4828 | * | |
4829 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup). | |
4830 | * | |
4831 | * We call cgroup_exit() while the task is still competent to | |
4832 | * handle notify_on_release(), then leave the task attached to the | |
4833 | * root cgroup in each hierarchy for the remainder of its exit. | |
4834 | * | |
4835 | * To do this properly, we would increment the reference count on | |
4836 | * top_cgroup, and near the very end of the kernel/exit.c do_exit() | |
4837 | * code we would add a second cgroup function call, to drop that | |
4838 | * reference. This would just create an unnecessary hot spot on | |
4839 | * the top_cgroup reference count, to no avail. | |
4840 | * | |
4841 | * Normally, holding a reference to a cgroup without bumping its | |
4842 | * count is unsafe. The cgroup could go away, or someone could | |
4843 | * attach us to a different cgroup, decrementing the count on | |
4844 | * the first cgroup that we never incremented. But in this case, | |
4845 | * top_cgroup isn't going away, and either task has PF_EXITING set, | |
956db3ca CW |
4846 | * which wards off any cgroup_attach_task() attempts, or task is a failed |
4847 | * fork, never visible to cgroup_attach_task. | |
b4f48b63 PM |
4848 | */ |
4849 | void cgroup_exit(struct task_struct *tsk, int run_callbacks) | |
4850 | { | |
817929ec | 4851 | struct css_set *cg; |
d41d5a01 | 4852 | int i; |
817929ec PM |
4853 | |
4854 | /* | |
4855 | * Unlink from the css_set task list if necessary. | |
4856 | * Optimistically check cg_list before taking | |
4857 | * css_set_lock | |
4858 | */ | |
4859 | if (!list_empty(&tsk->cg_list)) { | |
4860 | write_lock(&css_set_lock); | |
4861 | if (!list_empty(&tsk->cg_list)) | |
8d258797 | 4862 | list_del_init(&tsk->cg_list); |
817929ec PM |
4863 | write_unlock(&css_set_lock); |
4864 | } | |
4865 | ||
b4f48b63 PM |
4866 | /* Reassign the task to the init_css_set. */ |
4867 | task_lock(tsk); | |
817929ec PM |
4868 | cg = tsk->cgroups; |
4869 | tsk->cgroups = &init_css_set; | |
d41d5a01 PZ |
4870 | |
4871 | if (run_callbacks && need_forkexit_callback) { | |
4872 | /* | |
4873 | * modular subsystems can't use callbacks, so no need to lock | |
4874 | * the subsys array | |
4875 | */ | |
4876 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
4877 | struct cgroup_subsys *ss = subsys[i]; | |
4878 | if (ss->exit) { | |
4879 | struct cgroup *old_cgrp = | |
4880 | rcu_dereference_raw(cg->subsys[i])->cgroup; | |
4881 | struct cgroup *cgrp = task_cgroup(tsk, i); | |
761b3ef5 | 4882 | ss->exit(cgrp, old_cgrp, tsk); |
d41d5a01 PZ |
4883 | } |
4884 | } | |
4885 | } | |
b4f48b63 | 4886 | task_unlock(tsk); |
d41d5a01 | 4887 | |
817929ec | 4888 | if (cg) |
81a6a5cd | 4889 | put_css_set_taskexit(cg); |
b4f48b63 | 4890 | } |
697f4161 | 4891 | |
a043e3b2 | 4892 | /** |
313e924c | 4893 | * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp |
a043e3b2 | 4894 | * @cgrp: the cgroup in question |
313e924c | 4895 | * @task: the task in question |
a043e3b2 | 4896 | * |
313e924c GN |
4897 | * See if @cgrp is a descendant of @task's cgroup in the appropriate |
4898 | * hierarchy. | |
697f4161 PM |
4899 | * |
4900 | * If we are sending in dummytop, then presumably we are creating | |
4901 | * the top cgroup in the subsystem. | |
4902 | * | |
4903 | * Called only by the ns (nsproxy) cgroup. | |
4904 | */ | |
313e924c | 4905 | int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task) |
697f4161 PM |
4906 | { |
4907 | int ret; | |
4908 | struct cgroup *target; | |
697f4161 | 4909 | |
bd89aabc | 4910 | if (cgrp == dummytop) |
697f4161 PM |
4911 | return 1; |
4912 | ||
7717f7ba | 4913 | target = task_cgroup_from_root(task, cgrp->root); |
bd89aabc PM |
4914 | while (cgrp != target && cgrp!= cgrp->top_cgroup) |
4915 | cgrp = cgrp->parent; | |
4916 | ret = (cgrp == target); | |
697f4161 PM |
4917 | return ret; |
4918 | } | |
81a6a5cd | 4919 | |
bd89aabc | 4920 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd PM |
4921 | { |
4922 | /* All of these checks rely on RCU to keep the cgroup | |
4923 | * structure alive */ | |
bd89aabc PM |
4924 | if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count) |
4925 | && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) { | |
81a6a5cd PM |
4926 | /* Control Group is currently removeable. If it's not |
4927 | * already queued for a userspace notification, queue | |
4928 | * it now */ | |
4929 | int need_schedule_work = 0; | |
cdcc136f | 4930 | raw_spin_lock(&release_list_lock); |
bd89aabc PM |
4931 | if (!cgroup_is_removed(cgrp) && |
4932 | list_empty(&cgrp->release_list)) { | |
4933 | list_add(&cgrp->release_list, &release_list); | |
81a6a5cd PM |
4934 | need_schedule_work = 1; |
4935 | } | |
cdcc136f | 4936 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
4937 | if (need_schedule_work) |
4938 | schedule_work(&release_agent_work); | |
4939 | } | |
4940 | } | |
4941 | ||
d7b9fff7 | 4942 | /* Caller must verify that the css is not for root cgroup */ |
28b4c27b TH |
4943 | bool __css_tryget(struct cgroup_subsys_state *css) |
4944 | { | |
4945 | do { | |
4946 | int v = css_refcnt(css); | |
4947 | ||
4948 | if (atomic_cmpxchg(&css->refcnt, v, v + 1) == v) | |
4949 | return true; | |
4950 | cpu_relax(); | |
4951 | } while (!test_bit(CSS_REMOVED, &css->flags)); | |
4952 | ||
4953 | return false; | |
4954 | } | |
4955 | EXPORT_SYMBOL_GPL(__css_tryget); | |
4956 | ||
4957 | /* Caller must verify that the css is not for root cgroup */ | |
4958 | void __css_put(struct cgroup_subsys_state *css) | |
81a6a5cd | 4959 | { |
bd89aabc | 4960 | struct cgroup *cgrp = css->cgroup; |
28b4c27b | 4961 | |
81a6a5cd | 4962 | rcu_read_lock(); |
28b4c27b | 4963 | atomic_dec(&css->refcnt); |
48ddbe19 TH |
4964 | switch (css_refcnt(css)) { |
4965 | case 1: | |
ec64f515 KH |
4966 | if (notify_on_release(cgrp)) { |
4967 | set_bit(CGRP_RELEASABLE, &cgrp->flags); | |
4968 | check_for_release(cgrp); | |
4969 | } | |
88703267 | 4970 | cgroup_wakeup_rmdir_waiter(cgrp); |
48ddbe19 TH |
4971 | break; |
4972 | case 0: | |
4973 | if (!test_bit(CSS_CLEAR_CSS_REFS, &css->flags)) | |
4974 | schedule_work(&css->dput_work); | |
4975 | break; | |
81a6a5cd PM |
4976 | } |
4977 | rcu_read_unlock(); | |
4978 | } | |
67523c48 | 4979 | EXPORT_SYMBOL_GPL(__css_put); |
81a6a5cd PM |
4980 | |
4981 | /* | |
4982 | * Notify userspace when a cgroup is released, by running the | |
4983 | * configured release agent with the name of the cgroup (path | |
4984 | * relative to the root of cgroup file system) as the argument. | |
4985 | * | |
4986 | * Most likely, this user command will try to rmdir this cgroup. | |
4987 | * | |
4988 | * This races with the possibility that some other task will be | |
4989 | * attached to this cgroup before it is removed, or that some other | |
4990 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
4991 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
4992 | * unused, and this cgroup will be reprieved from its death sentence, | |
4993 | * to continue to serve a useful existence. Next time it's released, | |
4994 | * we will get notified again, if it still has 'notify_on_release' set. | |
4995 | * | |
4996 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
4997 | * means only wait until the task is successfully execve()'d. The | |
4998 | * separate release agent task is forked by call_usermodehelper(), | |
4999 | * then control in this thread returns here, without waiting for the | |
5000 | * release agent task. We don't bother to wait because the caller of | |
5001 | * this routine has no use for the exit status of the release agent | |
5002 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 5003 | */ |
81a6a5cd PM |
5004 | static void cgroup_release_agent(struct work_struct *work) |
5005 | { | |
5006 | BUG_ON(work != &release_agent_work); | |
5007 | mutex_lock(&cgroup_mutex); | |
cdcc136f | 5008 | raw_spin_lock(&release_list_lock); |
81a6a5cd PM |
5009 | while (!list_empty(&release_list)) { |
5010 | char *argv[3], *envp[3]; | |
5011 | int i; | |
e788e066 | 5012 | char *pathbuf = NULL, *agentbuf = NULL; |
bd89aabc | 5013 | struct cgroup *cgrp = list_entry(release_list.next, |
81a6a5cd PM |
5014 | struct cgroup, |
5015 | release_list); | |
bd89aabc | 5016 | list_del_init(&cgrp->release_list); |
cdcc136f | 5017 | raw_spin_unlock(&release_list_lock); |
81a6a5cd | 5018 | pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); |
e788e066 PM |
5019 | if (!pathbuf) |
5020 | goto continue_free; | |
5021 | if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) | |
5022 | goto continue_free; | |
5023 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
5024 | if (!agentbuf) | |
5025 | goto continue_free; | |
81a6a5cd PM |
5026 | |
5027 | i = 0; | |
e788e066 PM |
5028 | argv[i++] = agentbuf; |
5029 | argv[i++] = pathbuf; | |
81a6a5cd PM |
5030 | argv[i] = NULL; |
5031 | ||
5032 | i = 0; | |
5033 | /* minimal command environment */ | |
5034 | envp[i++] = "HOME=/"; | |
5035 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
5036 | envp[i] = NULL; | |
5037 | ||
5038 | /* Drop the lock while we invoke the usermode helper, | |
5039 | * since the exec could involve hitting disk and hence | |
5040 | * be a slow process */ | |
5041 | mutex_unlock(&cgroup_mutex); | |
5042 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
81a6a5cd | 5043 | mutex_lock(&cgroup_mutex); |
e788e066 PM |
5044 | continue_free: |
5045 | kfree(pathbuf); | |
5046 | kfree(agentbuf); | |
cdcc136f | 5047 | raw_spin_lock(&release_list_lock); |
81a6a5cd | 5048 | } |
cdcc136f | 5049 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
5050 | mutex_unlock(&cgroup_mutex); |
5051 | } | |
8bab8dde PM |
5052 | |
5053 | static int __init cgroup_disable(char *str) | |
5054 | { | |
5055 | int i; | |
5056 | char *token; | |
5057 | ||
5058 | while ((token = strsep(&str, ",")) != NULL) { | |
5059 | if (!*token) | |
5060 | continue; | |
aae8aab4 BB |
5061 | /* |
5062 | * cgroup_disable, being at boot time, can't know about module | |
5063 | * subsystems, so we don't worry about them. | |
5064 | */ | |
5065 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
8bab8dde PM |
5066 | struct cgroup_subsys *ss = subsys[i]; |
5067 | ||
5068 | if (!strcmp(token, ss->name)) { | |
5069 | ss->disabled = 1; | |
5070 | printk(KERN_INFO "Disabling %s control group" | |
5071 | " subsystem\n", ss->name); | |
5072 | break; | |
5073 | } | |
5074 | } | |
5075 | } | |
5076 | return 1; | |
5077 | } | |
5078 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 KH |
5079 | |
5080 | /* | |
5081 | * Functons for CSS ID. | |
5082 | */ | |
5083 | ||
5084 | /* | |
5085 | *To get ID other than 0, this should be called when !cgroup_is_removed(). | |
5086 | */ | |
5087 | unsigned short css_id(struct cgroup_subsys_state *css) | |
5088 | { | |
7f0f1546 KH |
5089 | struct css_id *cssid; |
5090 | ||
5091 | /* | |
5092 | * This css_id() can return correct value when somone has refcnt | |
5093 | * on this or this is under rcu_read_lock(). Once css->id is allocated, | |
5094 | * it's unchanged until freed. | |
5095 | */ | |
28b4c27b | 5096 | cssid = rcu_dereference_check(css->id, css_refcnt(css)); |
38460b48 KH |
5097 | |
5098 | if (cssid) | |
5099 | return cssid->id; | |
5100 | return 0; | |
5101 | } | |
67523c48 | 5102 | EXPORT_SYMBOL_GPL(css_id); |
38460b48 KH |
5103 | |
5104 | unsigned short css_depth(struct cgroup_subsys_state *css) | |
5105 | { | |
7f0f1546 KH |
5106 | struct css_id *cssid; |
5107 | ||
28b4c27b | 5108 | cssid = rcu_dereference_check(css->id, css_refcnt(css)); |
38460b48 KH |
5109 | |
5110 | if (cssid) | |
5111 | return cssid->depth; | |
5112 | return 0; | |
5113 | } | |
67523c48 | 5114 | EXPORT_SYMBOL_GPL(css_depth); |
38460b48 | 5115 | |
747388d7 KH |
5116 | /** |
5117 | * css_is_ancestor - test "root" css is an ancestor of "child" | |
5118 | * @child: the css to be tested. | |
5119 | * @root: the css supporsed to be an ancestor of the child. | |
5120 | * | |
5121 | * Returns true if "root" is an ancestor of "child" in its hierarchy. Because | |
5122 | * this function reads css->id, this use rcu_dereference() and rcu_read_lock(). | |
5123 | * But, considering usual usage, the csses should be valid objects after test. | |
5124 | * Assuming that the caller will do some action to the child if this returns | |
5125 | * returns true, the caller must take "child";s reference count. | |
5126 | * If "child" is valid object and this returns true, "root" is valid, too. | |
5127 | */ | |
5128 | ||
38460b48 | 5129 | bool css_is_ancestor(struct cgroup_subsys_state *child, |
0b7f569e | 5130 | const struct cgroup_subsys_state *root) |
38460b48 | 5131 | { |
747388d7 KH |
5132 | struct css_id *child_id; |
5133 | struct css_id *root_id; | |
5134 | bool ret = true; | |
38460b48 | 5135 | |
747388d7 KH |
5136 | rcu_read_lock(); |
5137 | child_id = rcu_dereference(child->id); | |
5138 | root_id = rcu_dereference(root->id); | |
5139 | if (!child_id | |
5140 | || !root_id | |
5141 | || (child_id->depth < root_id->depth) | |
5142 | || (child_id->stack[root_id->depth] != root_id->id)) | |
5143 | ret = false; | |
5144 | rcu_read_unlock(); | |
5145 | return ret; | |
38460b48 KH |
5146 | } |
5147 | ||
38460b48 KH |
5148 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) |
5149 | { | |
5150 | struct css_id *id = css->id; | |
5151 | /* When this is called before css_id initialization, id can be NULL */ | |
5152 | if (!id) | |
5153 | return; | |
5154 | ||
5155 | BUG_ON(!ss->use_id); | |
5156 | ||
5157 | rcu_assign_pointer(id->css, NULL); | |
5158 | rcu_assign_pointer(css->id, NULL); | |
42aee6c4 | 5159 | spin_lock(&ss->id_lock); |
38460b48 | 5160 | idr_remove(&ss->idr, id->id); |
42aee6c4 | 5161 | spin_unlock(&ss->id_lock); |
025cea99 | 5162 | kfree_rcu(id, rcu_head); |
38460b48 | 5163 | } |
67523c48 | 5164 | EXPORT_SYMBOL_GPL(free_css_id); |
38460b48 KH |
5165 | |
5166 | /* | |
5167 | * This is called by init or create(). Then, calls to this function are | |
5168 | * always serialized (By cgroup_mutex() at create()). | |
5169 | */ | |
5170 | ||
5171 | static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) | |
5172 | { | |
5173 | struct css_id *newid; | |
5174 | int myid, error, size; | |
5175 | ||
5176 | BUG_ON(!ss->use_id); | |
5177 | ||
5178 | size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); | |
5179 | newid = kzalloc(size, GFP_KERNEL); | |
5180 | if (!newid) | |
5181 | return ERR_PTR(-ENOMEM); | |
5182 | /* get id */ | |
5183 | if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) { | |
5184 | error = -ENOMEM; | |
5185 | goto err_out; | |
5186 | } | |
42aee6c4 | 5187 | spin_lock(&ss->id_lock); |
38460b48 KH |
5188 | /* Don't use 0. allocates an ID of 1-65535 */ |
5189 | error = idr_get_new_above(&ss->idr, newid, 1, &myid); | |
42aee6c4 | 5190 | spin_unlock(&ss->id_lock); |
38460b48 KH |
5191 | |
5192 | /* Returns error when there are no free spaces for new ID.*/ | |
5193 | if (error) { | |
5194 | error = -ENOSPC; | |
5195 | goto err_out; | |
5196 | } | |
5197 | if (myid > CSS_ID_MAX) | |
5198 | goto remove_idr; | |
5199 | ||
5200 | newid->id = myid; | |
5201 | newid->depth = depth; | |
5202 | return newid; | |
5203 | remove_idr: | |
5204 | error = -ENOSPC; | |
42aee6c4 | 5205 | spin_lock(&ss->id_lock); |
38460b48 | 5206 | idr_remove(&ss->idr, myid); |
42aee6c4 | 5207 | spin_unlock(&ss->id_lock); |
38460b48 KH |
5208 | err_out: |
5209 | kfree(newid); | |
5210 | return ERR_PTR(error); | |
5211 | ||
5212 | } | |
5213 | ||
e6a1105b BB |
5214 | static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, |
5215 | struct cgroup_subsys_state *rootcss) | |
38460b48 KH |
5216 | { |
5217 | struct css_id *newid; | |
38460b48 | 5218 | |
42aee6c4 | 5219 | spin_lock_init(&ss->id_lock); |
38460b48 KH |
5220 | idr_init(&ss->idr); |
5221 | ||
38460b48 KH |
5222 | newid = get_new_cssid(ss, 0); |
5223 | if (IS_ERR(newid)) | |
5224 | return PTR_ERR(newid); | |
5225 | ||
5226 | newid->stack[0] = newid->id; | |
5227 | newid->css = rootcss; | |
5228 | rootcss->id = newid; | |
5229 | return 0; | |
5230 | } | |
5231 | ||
5232 | static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, | |
5233 | struct cgroup *child) | |
5234 | { | |
5235 | int subsys_id, i, depth = 0; | |
5236 | struct cgroup_subsys_state *parent_css, *child_css; | |
fae9c791 | 5237 | struct css_id *child_id, *parent_id; |
38460b48 KH |
5238 | |
5239 | subsys_id = ss->subsys_id; | |
5240 | parent_css = parent->subsys[subsys_id]; | |
5241 | child_css = child->subsys[subsys_id]; | |
38460b48 | 5242 | parent_id = parent_css->id; |
94b3dd0f | 5243 | depth = parent_id->depth + 1; |
38460b48 KH |
5244 | |
5245 | child_id = get_new_cssid(ss, depth); | |
5246 | if (IS_ERR(child_id)) | |
5247 | return PTR_ERR(child_id); | |
5248 | ||
5249 | for (i = 0; i < depth; i++) | |
5250 | child_id->stack[i] = parent_id->stack[i]; | |
5251 | child_id->stack[depth] = child_id->id; | |
5252 | /* | |
5253 | * child_id->css pointer will be set after this cgroup is available | |
5254 | * see cgroup_populate_dir() | |
5255 | */ | |
5256 | rcu_assign_pointer(child_css->id, child_id); | |
5257 | ||
5258 | return 0; | |
5259 | } | |
5260 | ||
5261 | /** | |
5262 | * css_lookup - lookup css by id | |
5263 | * @ss: cgroup subsys to be looked into. | |
5264 | * @id: the id | |
5265 | * | |
5266 | * Returns pointer to cgroup_subsys_state if there is valid one with id. | |
5267 | * NULL if not. Should be called under rcu_read_lock() | |
5268 | */ | |
5269 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) | |
5270 | { | |
5271 | struct css_id *cssid = NULL; | |
5272 | ||
5273 | BUG_ON(!ss->use_id); | |
5274 | cssid = idr_find(&ss->idr, id); | |
5275 | ||
5276 | if (unlikely(!cssid)) | |
5277 | return NULL; | |
5278 | ||
5279 | return rcu_dereference(cssid->css); | |
5280 | } | |
67523c48 | 5281 | EXPORT_SYMBOL_GPL(css_lookup); |
38460b48 KH |
5282 | |
5283 | /** | |
5284 | * css_get_next - lookup next cgroup under specified hierarchy. | |
5285 | * @ss: pointer to subsystem | |
5286 | * @id: current position of iteration. | |
5287 | * @root: pointer to css. search tree under this. | |
5288 | * @foundid: position of found object. | |
5289 | * | |
5290 | * Search next css under the specified hierarchy of rootid. Calling under | |
5291 | * rcu_read_lock() is necessary. Returns NULL if it reaches the end. | |
5292 | */ | |
5293 | struct cgroup_subsys_state * | |
5294 | css_get_next(struct cgroup_subsys *ss, int id, | |
5295 | struct cgroup_subsys_state *root, int *foundid) | |
5296 | { | |
5297 | struct cgroup_subsys_state *ret = NULL; | |
5298 | struct css_id *tmp; | |
5299 | int tmpid; | |
5300 | int rootid = css_id(root); | |
5301 | int depth = css_depth(root); | |
5302 | ||
5303 | if (!rootid) | |
5304 | return NULL; | |
5305 | ||
5306 | BUG_ON(!ss->use_id); | |
ca464d69 HD |
5307 | WARN_ON_ONCE(!rcu_read_lock_held()); |
5308 | ||
38460b48 KH |
5309 | /* fill start point for scan */ |
5310 | tmpid = id; | |
5311 | while (1) { | |
5312 | /* | |
5313 | * scan next entry from bitmap(tree), tmpid is updated after | |
5314 | * idr_get_next(). | |
5315 | */ | |
38460b48 | 5316 | tmp = idr_get_next(&ss->idr, &tmpid); |
38460b48 KH |
5317 | if (!tmp) |
5318 | break; | |
5319 | if (tmp->depth >= depth && tmp->stack[depth] == rootid) { | |
5320 | ret = rcu_dereference(tmp->css); | |
5321 | if (ret) { | |
5322 | *foundid = tmpid; | |
5323 | break; | |
5324 | } | |
5325 | } | |
5326 | /* continue to scan from next id */ | |
5327 | tmpid = tmpid + 1; | |
5328 | } | |
5329 | return ret; | |
5330 | } | |
5331 | ||
e5d1367f SE |
5332 | /* |
5333 | * get corresponding css from file open on cgroupfs directory | |
5334 | */ | |
5335 | struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) | |
5336 | { | |
5337 | struct cgroup *cgrp; | |
5338 | struct inode *inode; | |
5339 | struct cgroup_subsys_state *css; | |
5340 | ||
5341 | inode = f->f_dentry->d_inode; | |
5342 | /* check in cgroup filesystem dir */ | |
5343 | if (inode->i_op != &cgroup_dir_inode_operations) | |
5344 | return ERR_PTR(-EBADF); | |
5345 | ||
5346 | if (id < 0 || id >= CGROUP_SUBSYS_COUNT) | |
5347 | return ERR_PTR(-EINVAL); | |
5348 | ||
5349 | /* get cgroup */ | |
5350 | cgrp = __d_cgrp(f->f_dentry); | |
5351 | css = cgrp->subsys[id]; | |
5352 | return css ? css : ERR_PTR(-ENOENT); | |
5353 | } | |
5354 | ||
fe693435 | 5355 | #ifdef CONFIG_CGROUP_DEBUG |
761b3ef5 | 5356 | static struct cgroup_subsys_state *debug_create(struct cgroup *cont) |
fe693435 PM |
5357 | { |
5358 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5359 | ||
5360 | if (!css) | |
5361 | return ERR_PTR(-ENOMEM); | |
5362 | ||
5363 | return css; | |
5364 | } | |
5365 | ||
761b3ef5 | 5366 | static void debug_destroy(struct cgroup *cont) |
fe693435 PM |
5367 | { |
5368 | kfree(cont->subsys[debug_subsys_id]); | |
5369 | } | |
5370 | ||
5371 | static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft) | |
5372 | { | |
5373 | return atomic_read(&cont->count); | |
5374 | } | |
5375 | ||
5376 | static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft) | |
5377 | { | |
5378 | return cgroup_task_count(cont); | |
5379 | } | |
5380 | ||
5381 | static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft) | |
5382 | { | |
5383 | return (u64)(unsigned long)current->cgroups; | |
5384 | } | |
5385 | ||
5386 | static u64 current_css_set_refcount_read(struct cgroup *cont, | |
5387 | struct cftype *cft) | |
5388 | { | |
5389 | u64 count; | |
5390 | ||
5391 | rcu_read_lock(); | |
5392 | count = atomic_read(¤t->cgroups->refcount); | |
5393 | rcu_read_unlock(); | |
5394 | return count; | |
5395 | } | |
5396 | ||
7717f7ba PM |
5397 | static int current_css_set_cg_links_read(struct cgroup *cont, |
5398 | struct cftype *cft, | |
5399 | struct seq_file *seq) | |
5400 | { | |
5401 | struct cg_cgroup_link *link; | |
5402 | struct css_set *cg; | |
5403 | ||
5404 | read_lock(&css_set_lock); | |
5405 | rcu_read_lock(); | |
5406 | cg = rcu_dereference(current->cgroups); | |
5407 | list_for_each_entry(link, &cg->cg_links, cg_link_list) { | |
5408 | struct cgroup *c = link->cgrp; | |
5409 | const char *name; | |
5410 | ||
5411 | if (c->dentry) | |
5412 | name = c->dentry->d_name.name; | |
5413 | else | |
5414 | name = "?"; | |
2c6ab6d2 PM |
5415 | seq_printf(seq, "Root %d group %s\n", |
5416 | c->root->hierarchy_id, name); | |
7717f7ba PM |
5417 | } |
5418 | rcu_read_unlock(); | |
5419 | read_unlock(&css_set_lock); | |
5420 | return 0; | |
5421 | } | |
5422 | ||
5423 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
5424 | static int cgroup_css_links_read(struct cgroup *cont, | |
5425 | struct cftype *cft, | |
5426 | struct seq_file *seq) | |
5427 | { | |
5428 | struct cg_cgroup_link *link; | |
5429 | ||
5430 | read_lock(&css_set_lock); | |
5431 | list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { | |
5432 | struct css_set *cg = link->cg; | |
5433 | struct task_struct *task; | |
5434 | int count = 0; | |
5435 | seq_printf(seq, "css_set %p\n", cg); | |
5436 | list_for_each_entry(task, &cg->tasks, cg_list) { | |
5437 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) { | |
5438 | seq_puts(seq, " ...\n"); | |
5439 | break; | |
5440 | } else { | |
5441 | seq_printf(seq, " task %d\n", | |
5442 | task_pid_vnr(task)); | |
5443 | } | |
5444 | } | |
5445 | } | |
5446 | read_unlock(&css_set_lock); | |
5447 | return 0; | |
5448 | } | |
5449 | ||
fe693435 PM |
5450 | static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft) |
5451 | { | |
5452 | return test_bit(CGRP_RELEASABLE, &cgrp->flags); | |
5453 | } | |
5454 | ||
5455 | static struct cftype debug_files[] = { | |
5456 | { | |
5457 | .name = "cgroup_refcount", | |
5458 | .read_u64 = cgroup_refcount_read, | |
5459 | }, | |
5460 | { | |
5461 | .name = "taskcount", | |
5462 | .read_u64 = debug_taskcount_read, | |
5463 | }, | |
5464 | ||
5465 | { | |
5466 | .name = "current_css_set", | |
5467 | .read_u64 = current_css_set_read, | |
5468 | }, | |
5469 | ||
5470 | { | |
5471 | .name = "current_css_set_refcount", | |
5472 | .read_u64 = current_css_set_refcount_read, | |
5473 | }, | |
5474 | ||
7717f7ba PM |
5475 | { |
5476 | .name = "current_css_set_cg_links", | |
5477 | .read_seq_string = current_css_set_cg_links_read, | |
5478 | }, | |
5479 | ||
5480 | { | |
5481 | .name = "cgroup_css_links", | |
5482 | .read_seq_string = cgroup_css_links_read, | |
5483 | }, | |
5484 | ||
fe693435 PM |
5485 | { |
5486 | .name = "releasable", | |
5487 | .read_u64 = releasable_read, | |
5488 | }, | |
fe693435 | 5489 | |
4baf6e33 TH |
5490 | { } /* terminate */ |
5491 | }; | |
fe693435 PM |
5492 | |
5493 | struct cgroup_subsys debug_subsys = { | |
5494 | .name = "debug", | |
5495 | .create = debug_create, | |
5496 | .destroy = debug_destroy, | |
fe693435 | 5497 | .subsys_id = debug_subsys_id, |
4baf6e33 | 5498 | .base_cftypes = debug_files, |
fe693435 PM |
5499 | }; |
5500 | #endif /* CONFIG_CGROUP_DEBUG */ |