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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 | |
e25e2cbb TH |
66 | /* |
67 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
68 | * hierarchy must be performed while holding it. | |
69 | * | |
70 | * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify | |
71 | * cgroupfs_root of any cgroup hierarchy - subsys list, flags, | |
72 | * release_agent_path and so on. Modifying requires both cgroup_mutex and | |
73 | * cgroup_root_mutex. Readers can acquire either of the two. This is to | |
74 | * break the following locking order cycle. | |
75 | * | |
76 | * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem | |
77 | * B. namespace_sem -> cgroup_mutex | |
78 | * | |
79 | * B happens only through cgroup_show_options() and using cgroup_root_mutex | |
80 | * breaks it. | |
81 | */ | |
81a6a5cd | 82 | static DEFINE_MUTEX(cgroup_mutex); |
e25e2cbb | 83 | static DEFINE_MUTEX(cgroup_root_mutex); |
81a6a5cd | 84 | |
aae8aab4 BB |
85 | /* |
86 | * Generate an array of cgroup subsystem pointers. At boot time, this is | |
87 | * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are | |
88 | * registered after that. The mutable section of this array is protected by | |
89 | * cgroup_mutex. | |
90 | */ | |
ddbcc7e8 | 91 | #define SUBSYS(_x) &_x ## _subsys, |
aae8aab4 | 92 | static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = { |
ddbcc7e8 PM |
93 | #include <linux/cgroup_subsys.h> |
94 | }; | |
95 | ||
c6d57f33 PM |
96 | #define MAX_CGROUP_ROOT_NAMELEN 64 |
97 | ||
ddbcc7e8 PM |
98 | /* |
99 | * A cgroupfs_root represents the root of a cgroup hierarchy, | |
100 | * and may be associated with a superblock to form an active | |
101 | * hierarchy | |
102 | */ | |
103 | struct cgroupfs_root { | |
104 | struct super_block *sb; | |
105 | ||
106 | /* | |
107 | * The bitmask of subsystems intended to be attached to this | |
108 | * hierarchy | |
109 | */ | |
110 | unsigned long subsys_bits; | |
111 | ||
2c6ab6d2 PM |
112 | /* Unique id for this hierarchy. */ |
113 | int hierarchy_id; | |
114 | ||
ddbcc7e8 PM |
115 | /* The bitmask of subsystems currently attached to this hierarchy */ |
116 | unsigned long actual_subsys_bits; | |
117 | ||
118 | /* A list running through the attached subsystems */ | |
119 | struct list_head subsys_list; | |
120 | ||
121 | /* The root cgroup for this hierarchy */ | |
122 | struct cgroup top_cgroup; | |
123 | ||
124 | /* Tracks how many cgroups are currently defined in hierarchy.*/ | |
125 | int number_of_cgroups; | |
126 | ||
e5f6a860 | 127 | /* A list running through the active hierarchies */ |
ddbcc7e8 PM |
128 | struct list_head root_list; |
129 | ||
b0ca5a84 TH |
130 | /* All cgroups on this root, cgroup_mutex protected */ |
131 | struct list_head allcg_list; | |
132 | ||
ddbcc7e8 PM |
133 | /* Hierarchy-specific flags */ |
134 | unsigned long flags; | |
81a6a5cd | 135 | |
e788e066 | 136 | /* The path to use for release notifications. */ |
81a6a5cd | 137 | char release_agent_path[PATH_MAX]; |
c6d57f33 PM |
138 | |
139 | /* The name for this hierarchy - may be empty */ | |
140 | char name[MAX_CGROUP_ROOT_NAMELEN]; | |
ddbcc7e8 PM |
141 | }; |
142 | ||
ddbcc7e8 PM |
143 | /* |
144 | * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the | |
145 | * subsystems that are otherwise unattached - it never has more than a | |
146 | * single cgroup, and all tasks are part of that cgroup. | |
147 | */ | |
148 | static struct cgroupfs_root rootnode; | |
149 | ||
38460b48 KH |
150 | /* |
151 | * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when | |
152 | * cgroup_subsys->use_id != 0. | |
153 | */ | |
154 | #define CSS_ID_MAX (65535) | |
155 | struct css_id { | |
156 | /* | |
157 | * The css to which this ID points. This pointer is set to valid value | |
158 | * after cgroup is populated. If cgroup is removed, this will be NULL. | |
159 | * This pointer is expected to be RCU-safe because destroy() | |
160 | * is called after synchronize_rcu(). But for safe use, css_is_removed() | |
161 | * css_tryget() should be used for avoiding race. | |
162 | */ | |
2c392b8c | 163 | struct cgroup_subsys_state __rcu *css; |
38460b48 KH |
164 | /* |
165 | * ID of this css. | |
166 | */ | |
167 | unsigned short id; | |
168 | /* | |
169 | * Depth in hierarchy which this ID belongs to. | |
170 | */ | |
171 | unsigned short depth; | |
172 | /* | |
173 | * ID is freed by RCU. (and lookup routine is RCU safe.) | |
174 | */ | |
175 | struct rcu_head rcu_head; | |
176 | /* | |
177 | * Hierarchy of CSS ID belongs to. | |
178 | */ | |
179 | unsigned short stack[0]; /* Array of Length (depth+1) */ | |
180 | }; | |
181 | ||
0dea1168 | 182 | /* |
25985edc | 183 | * cgroup_event represents events which userspace want to receive. |
0dea1168 KS |
184 | */ |
185 | struct cgroup_event { | |
186 | /* | |
187 | * Cgroup which the event belongs to. | |
188 | */ | |
189 | struct cgroup *cgrp; | |
190 | /* | |
191 | * Control file which the event associated. | |
192 | */ | |
193 | struct cftype *cft; | |
194 | /* | |
195 | * eventfd to signal userspace about the event. | |
196 | */ | |
197 | struct eventfd_ctx *eventfd; | |
198 | /* | |
199 | * Each of these stored in a list by the cgroup. | |
200 | */ | |
201 | struct list_head list; | |
202 | /* | |
203 | * All fields below needed to unregister event when | |
204 | * userspace closes eventfd. | |
205 | */ | |
206 | poll_table pt; | |
207 | wait_queue_head_t *wqh; | |
208 | wait_queue_t wait; | |
209 | struct work_struct remove; | |
210 | }; | |
38460b48 | 211 | |
ddbcc7e8 PM |
212 | /* The list of hierarchy roots */ |
213 | ||
214 | static LIST_HEAD(roots); | |
817929ec | 215 | static int root_count; |
ddbcc7e8 | 216 | |
2c6ab6d2 PM |
217 | static DEFINE_IDA(hierarchy_ida); |
218 | static int next_hierarchy_id; | |
219 | static DEFINE_SPINLOCK(hierarchy_id_lock); | |
220 | ||
ddbcc7e8 PM |
221 | /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ |
222 | #define dummytop (&rootnode.top_cgroup) | |
223 | ||
224 | /* This flag indicates whether tasks in the fork and exit paths should | |
a043e3b2 LZ |
225 | * check for fork/exit handlers to call. This avoids us having to do |
226 | * extra work in the fork/exit path if none of the subsystems need to | |
227 | * be called. | |
ddbcc7e8 | 228 | */ |
8947f9d5 | 229 | static int need_forkexit_callback __read_mostly; |
ddbcc7e8 | 230 | |
d11c563d PM |
231 | #ifdef CONFIG_PROVE_LOCKING |
232 | int cgroup_lock_is_held(void) | |
233 | { | |
234 | return lockdep_is_held(&cgroup_mutex); | |
235 | } | |
236 | #else /* #ifdef CONFIG_PROVE_LOCKING */ | |
237 | int cgroup_lock_is_held(void) | |
238 | { | |
239 | return mutex_is_locked(&cgroup_mutex); | |
240 | } | |
241 | #endif /* #else #ifdef CONFIG_PROVE_LOCKING */ | |
242 | ||
243 | EXPORT_SYMBOL_GPL(cgroup_lock_is_held); | |
244 | ||
ddbcc7e8 | 245 | /* convenient tests for these bits */ |
bd89aabc | 246 | inline int cgroup_is_removed(const struct cgroup *cgrp) |
ddbcc7e8 | 247 | { |
bd89aabc | 248 | return test_bit(CGRP_REMOVED, &cgrp->flags); |
ddbcc7e8 PM |
249 | } |
250 | ||
251 | /* bits in struct cgroupfs_root flags field */ | |
252 | enum { | |
253 | ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ | |
254 | }; | |
255 | ||
e9685a03 | 256 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
81a6a5cd PM |
257 | { |
258 | const int bits = | |
bd89aabc PM |
259 | (1 << CGRP_RELEASABLE) | |
260 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
261 | return (cgrp->flags & bits) == bits; | |
81a6a5cd PM |
262 | } |
263 | ||
e9685a03 | 264 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 265 | { |
bd89aabc | 266 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
267 | } |
268 | ||
97978e6d DL |
269 | static int clone_children(const struct cgroup *cgrp) |
270 | { | |
271 | return test_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
272 | } | |
273 | ||
ddbcc7e8 PM |
274 | /* |
275 | * for_each_subsys() allows you to iterate on each subsystem attached to | |
276 | * an active hierarchy | |
277 | */ | |
278 | #define for_each_subsys(_root, _ss) \ | |
279 | list_for_each_entry(_ss, &_root->subsys_list, sibling) | |
280 | ||
e5f6a860 LZ |
281 | /* for_each_active_root() allows you to iterate across the active hierarchies */ |
282 | #define for_each_active_root(_root) \ | |
ddbcc7e8 PM |
283 | list_for_each_entry(_root, &roots, root_list) |
284 | ||
81a6a5cd PM |
285 | /* the list of cgroups eligible for automatic release. Protected by |
286 | * release_list_lock */ | |
287 | static LIST_HEAD(release_list); | |
cdcc136f | 288 | static DEFINE_RAW_SPINLOCK(release_list_lock); |
81a6a5cd PM |
289 | static void cgroup_release_agent(struct work_struct *work); |
290 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
bd89aabc | 291 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 292 | |
817929ec PM |
293 | /* Link structure for associating css_set objects with cgroups */ |
294 | struct cg_cgroup_link { | |
295 | /* | |
296 | * List running through cg_cgroup_links associated with a | |
297 | * cgroup, anchored on cgroup->css_sets | |
298 | */ | |
bd89aabc | 299 | struct list_head cgrp_link_list; |
7717f7ba | 300 | struct cgroup *cgrp; |
817929ec PM |
301 | /* |
302 | * List running through cg_cgroup_links pointing at a | |
303 | * single css_set object, anchored on css_set->cg_links | |
304 | */ | |
305 | struct list_head cg_link_list; | |
306 | struct css_set *cg; | |
307 | }; | |
308 | ||
309 | /* The default css_set - used by init and its children prior to any | |
310 | * hierarchies being mounted. It contains a pointer to the root state | |
311 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
312 | * reference-counted, to improve performance when child cgroups | |
313 | * haven't been created. | |
314 | */ | |
315 | ||
316 | static struct css_set init_css_set; | |
317 | static struct cg_cgroup_link init_css_set_link; | |
318 | ||
e6a1105b BB |
319 | static int cgroup_init_idr(struct cgroup_subsys *ss, |
320 | struct cgroup_subsys_state *css); | |
38460b48 | 321 | |
817929ec PM |
322 | /* css_set_lock protects the list of css_set objects, and the |
323 | * chain of tasks off each css_set. Nests outside task->alloc_lock | |
324 | * due to cgroup_iter_start() */ | |
325 | static DEFINE_RWLOCK(css_set_lock); | |
326 | static int css_set_count; | |
327 | ||
7717f7ba PM |
328 | /* |
329 | * hash table for cgroup groups. This improves the performance to find | |
330 | * an existing css_set. This hash doesn't (currently) take into | |
331 | * account cgroups in empty hierarchies. | |
332 | */ | |
472b1053 LZ |
333 | #define CSS_SET_HASH_BITS 7 |
334 | #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS) | |
335 | static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE]; | |
336 | ||
337 | static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) | |
338 | { | |
339 | int i; | |
340 | int index; | |
341 | unsigned long tmp = 0UL; | |
342 | ||
343 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) | |
344 | tmp += (unsigned long)css[i]; | |
345 | tmp = (tmp >> 16) ^ tmp; | |
346 | ||
347 | index = hash_long(tmp, CSS_SET_HASH_BITS); | |
348 | ||
349 | return &css_set_table[index]; | |
350 | } | |
351 | ||
817929ec PM |
352 | /* We don't maintain the lists running through each css_set to its |
353 | * task until after the first call to cgroup_iter_start(). This | |
354 | * reduces the fork()/exit() overhead for people who have cgroups | |
355 | * compiled into their kernel but not actually in use */ | |
8947f9d5 | 356 | static int use_task_css_set_links __read_mostly; |
817929ec | 357 | |
2c6ab6d2 | 358 | static void __put_css_set(struct css_set *cg, int taskexit) |
b4f48b63 | 359 | { |
71cbb949 KM |
360 | struct cg_cgroup_link *link; |
361 | struct cg_cgroup_link *saved_link; | |
146aa1bd LJ |
362 | /* |
363 | * Ensure that the refcount doesn't hit zero while any readers | |
364 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
365 | * rwlock | |
366 | */ | |
367 | if (atomic_add_unless(&cg->refcount, -1, 1)) | |
368 | return; | |
369 | write_lock(&css_set_lock); | |
370 | if (!atomic_dec_and_test(&cg->refcount)) { | |
371 | write_unlock(&css_set_lock); | |
372 | return; | |
373 | } | |
81a6a5cd | 374 | |
2c6ab6d2 PM |
375 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
376 | hlist_del(&cg->hlist); | |
377 | css_set_count--; | |
378 | ||
379 | list_for_each_entry_safe(link, saved_link, &cg->cg_links, | |
380 | cg_link_list) { | |
381 | struct cgroup *cgrp = link->cgrp; | |
382 | list_del(&link->cg_link_list); | |
383 | list_del(&link->cgrp_link_list); | |
bd89aabc PM |
384 | if (atomic_dec_and_test(&cgrp->count) && |
385 | notify_on_release(cgrp)) { | |
81a6a5cd | 386 | if (taskexit) |
bd89aabc PM |
387 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
388 | check_for_release(cgrp); | |
81a6a5cd | 389 | } |
2c6ab6d2 PM |
390 | |
391 | kfree(link); | |
81a6a5cd | 392 | } |
2c6ab6d2 PM |
393 | |
394 | write_unlock(&css_set_lock); | |
30088ad8 | 395 | kfree_rcu(cg, rcu_head); |
b4f48b63 PM |
396 | } |
397 | ||
817929ec PM |
398 | /* |
399 | * refcounted get/put for css_set objects | |
400 | */ | |
401 | static inline void get_css_set(struct css_set *cg) | |
402 | { | |
146aa1bd | 403 | atomic_inc(&cg->refcount); |
817929ec PM |
404 | } |
405 | ||
406 | static inline void put_css_set(struct css_set *cg) | |
407 | { | |
146aa1bd | 408 | __put_css_set(cg, 0); |
817929ec PM |
409 | } |
410 | ||
81a6a5cd PM |
411 | static inline void put_css_set_taskexit(struct css_set *cg) |
412 | { | |
146aa1bd | 413 | __put_css_set(cg, 1); |
81a6a5cd PM |
414 | } |
415 | ||
7717f7ba PM |
416 | /* |
417 | * compare_css_sets - helper function for find_existing_css_set(). | |
418 | * @cg: candidate css_set being tested | |
419 | * @old_cg: existing css_set for a task | |
420 | * @new_cgrp: cgroup that's being entered by the task | |
421 | * @template: desired set of css pointers in css_set (pre-calculated) | |
422 | * | |
423 | * Returns true if "cg" matches "old_cg" except for the hierarchy | |
424 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". | |
425 | */ | |
426 | static bool compare_css_sets(struct css_set *cg, | |
427 | struct css_set *old_cg, | |
428 | struct cgroup *new_cgrp, | |
429 | struct cgroup_subsys_state *template[]) | |
430 | { | |
431 | struct list_head *l1, *l2; | |
432 | ||
433 | if (memcmp(template, cg->subsys, sizeof(cg->subsys))) { | |
434 | /* Not all subsystems matched */ | |
435 | return false; | |
436 | } | |
437 | ||
438 | /* | |
439 | * Compare cgroup pointers in order to distinguish between | |
440 | * different cgroups in heirarchies with no subsystems. We | |
441 | * could get by with just this check alone (and skip the | |
442 | * memcmp above) but on most setups the memcmp check will | |
443 | * avoid the need for this more expensive check on almost all | |
444 | * candidates. | |
445 | */ | |
446 | ||
447 | l1 = &cg->cg_links; | |
448 | l2 = &old_cg->cg_links; | |
449 | while (1) { | |
450 | struct cg_cgroup_link *cgl1, *cgl2; | |
451 | struct cgroup *cg1, *cg2; | |
452 | ||
453 | l1 = l1->next; | |
454 | l2 = l2->next; | |
455 | /* See if we reached the end - both lists are equal length. */ | |
456 | if (l1 == &cg->cg_links) { | |
457 | BUG_ON(l2 != &old_cg->cg_links); | |
458 | break; | |
459 | } else { | |
460 | BUG_ON(l2 == &old_cg->cg_links); | |
461 | } | |
462 | /* Locate the cgroups associated with these links. */ | |
463 | cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list); | |
464 | cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list); | |
465 | cg1 = cgl1->cgrp; | |
466 | cg2 = cgl2->cgrp; | |
467 | /* Hierarchies should be linked in the same order. */ | |
468 | BUG_ON(cg1->root != cg2->root); | |
469 | ||
470 | /* | |
471 | * If this hierarchy is the hierarchy of the cgroup | |
472 | * that's changing, then we need to check that this | |
473 | * css_set points to the new cgroup; if it's any other | |
474 | * hierarchy, then this css_set should point to the | |
475 | * same cgroup as the old css_set. | |
476 | */ | |
477 | if (cg1->root == new_cgrp->root) { | |
478 | if (cg1 != new_cgrp) | |
479 | return false; | |
480 | } else { | |
481 | if (cg1 != cg2) | |
482 | return false; | |
483 | } | |
484 | } | |
485 | return true; | |
486 | } | |
487 | ||
817929ec PM |
488 | /* |
489 | * find_existing_css_set() is a helper for | |
490 | * find_css_set(), and checks to see whether an existing | |
472b1053 | 491 | * css_set is suitable. |
817929ec PM |
492 | * |
493 | * oldcg: the cgroup group that we're using before the cgroup | |
494 | * transition | |
495 | * | |
bd89aabc | 496 | * cgrp: the cgroup that we're moving into |
817929ec PM |
497 | * |
498 | * template: location in which to build the desired set of subsystem | |
499 | * state objects for the new cgroup group | |
500 | */ | |
817929ec PM |
501 | static struct css_set *find_existing_css_set( |
502 | struct css_set *oldcg, | |
bd89aabc | 503 | struct cgroup *cgrp, |
817929ec | 504 | struct cgroup_subsys_state *template[]) |
b4f48b63 PM |
505 | { |
506 | int i; | |
bd89aabc | 507 | struct cgroupfs_root *root = cgrp->root; |
472b1053 LZ |
508 | struct hlist_head *hhead; |
509 | struct hlist_node *node; | |
510 | struct css_set *cg; | |
817929ec | 511 | |
aae8aab4 BB |
512 | /* |
513 | * Build the set of subsystem state objects that we want to see in the | |
514 | * new css_set. while subsystems can change globally, the entries here | |
515 | * won't change, so no need for locking. | |
516 | */ | |
817929ec | 517 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
8d53d55d | 518 | if (root->subsys_bits & (1UL << i)) { |
817929ec PM |
519 | /* Subsystem is in this hierarchy. So we want |
520 | * the subsystem state from the new | |
521 | * cgroup */ | |
bd89aabc | 522 | template[i] = cgrp->subsys[i]; |
817929ec PM |
523 | } else { |
524 | /* Subsystem is not in this hierarchy, so we | |
525 | * don't want to change the subsystem state */ | |
526 | template[i] = oldcg->subsys[i]; | |
527 | } | |
528 | } | |
529 | ||
472b1053 LZ |
530 | hhead = css_set_hash(template); |
531 | hlist_for_each_entry(cg, node, hhead, hlist) { | |
7717f7ba PM |
532 | if (!compare_css_sets(cg, oldcg, cgrp, template)) |
533 | continue; | |
534 | ||
535 | /* This css_set matches what we need */ | |
536 | return cg; | |
472b1053 | 537 | } |
817929ec PM |
538 | |
539 | /* No existing cgroup group matched */ | |
540 | return NULL; | |
541 | } | |
542 | ||
36553434 LZ |
543 | static void free_cg_links(struct list_head *tmp) |
544 | { | |
545 | struct cg_cgroup_link *link; | |
546 | struct cg_cgroup_link *saved_link; | |
547 | ||
548 | list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) { | |
549 | list_del(&link->cgrp_link_list); | |
550 | kfree(link); | |
551 | } | |
552 | } | |
553 | ||
817929ec PM |
554 | /* |
555 | * allocate_cg_links() allocates "count" cg_cgroup_link structures | |
bd89aabc | 556 | * and chains them on tmp through their cgrp_link_list fields. Returns 0 on |
817929ec PM |
557 | * success or a negative error |
558 | */ | |
817929ec PM |
559 | static int allocate_cg_links(int count, struct list_head *tmp) |
560 | { | |
561 | struct cg_cgroup_link *link; | |
562 | int i; | |
563 | INIT_LIST_HEAD(tmp); | |
564 | for (i = 0; i < count; i++) { | |
565 | link = kmalloc(sizeof(*link), GFP_KERNEL); | |
566 | if (!link) { | |
36553434 | 567 | free_cg_links(tmp); |
817929ec PM |
568 | return -ENOMEM; |
569 | } | |
bd89aabc | 570 | list_add(&link->cgrp_link_list, tmp); |
817929ec PM |
571 | } |
572 | return 0; | |
573 | } | |
574 | ||
c12f65d4 LZ |
575 | /** |
576 | * link_css_set - a helper function to link a css_set to a cgroup | |
577 | * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links() | |
578 | * @cg: the css_set to be linked | |
579 | * @cgrp: the destination cgroup | |
580 | */ | |
581 | static void link_css_set(struct list_head *tmp_cg_links, | |
582 | struct css_set *cg, struct cgroup *cgrp) | |
583 | { | |
584 | struct cg_cgroup_link *link; | |
585 | ||
586 | BUG_ON(list_empty(tmp_cg_links)); | |
587 | link = list_first_entry(tmp_cg_links, struct cg_cgroup_link, | |
588 | cgrp_link_list); | |
589 | link->cg = cg; | |
7717f7ba | 590 | link->cgrp = cgrp; |
2c6ab6d2 | 591 | atomic_inc(&cgrp->count); |
c12f65d4 | 592 | list_move(&link->cgrp_link_list, &cgrp->css_sets); |
7717f7ba PM |
593 | /* |
594 | * Always add links to the tail of the list so that the list | |
595 | * is sorted by order of hierarchy creation | |
596 | */ | |
597 | list_add_tail(&link->cg_link_list, &cg->cg_links); | |
c12f65d4 LZ |
598 | } |
599 | ||
817929ec PM |
600 | /* |
601 | * find_css_set() takes an existing cgroup group and a | |
602 | * cgroup object, and returns a css_set object that's | |
603 | * equivalent to the old group, but with the given cgroup | |
604 | * substituted into the appropriate hierarchy. Must be called with | |
605 | * cgroup_mutex held | |
606 | */ | |
817929ec | 607 | static struct css_set *find_css_set( |
bd89aabc | 608 | struct css_set *oldcg, struct cgroup *cgrp) |
817929ec PM |
609 | { |
610 | struct css_set *res; | |
611 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT]; | |
817929ec PM |
612 | |
613 | struct list_head tmp_cg_links; | |
817929ec | 614 | |
472b1053 | 615 | struct hlist_head *hhead; |
7717f7ba | 616 | struct cg_cgroup_link *link; |
472b1053 | 617 | |
817929ec PM |
618 | /* First see if we already have a cgroup group that matches |
619 | * the desired set */ | |
7e9abd89 | 620 | read_lock(&css_set_lock); |
bd89aabc | 621 | res = find_existing_css_set(oldcg, cgrp, template); |
817929ec PM |
622 | if (res) |
623 | get_css_set(res); | |
7e9abd89 | 624 | read_unlock(&css_set_lock); |
817929ec PM |
625 | |
626 | if (res) | |
627 | return res; | |
628 | ||
629 | res = kmalloc(sizeof(*res), GFP_KERNEL); | |
630 | if (!res) | |
631 | return NULL; | |
632 | ||
633 | /* Allocate all the cg_cgroup_link objects that we'll need */ | |
634 | if (allocate_cg_links(root_count, &tmp_cg_links) < 0) { | |
635 | kfree(res); | |
636 | return NULL; | |
637 | } | |
638 | ||
146aa1bd | 639 | atomic_set(&res->refcount, 1); |
817929ec PM |
640 | INIT_LIST_HEAD(&res->cg_links); |
641 | INIT_LIST_HEAD(&res->tasks); | |
472b1053 | 642 | INIT_HLIST_NODE(&res->hlist); |
817929ec PM |
643 | |
644 | /* Copy the set of subsystem state objects generated in | |
645 | * find_existing_css_set() */ | |
646 | memcpy(res->subsys, template, sizeof(res->subsys)); | |
647 | ||
648 | write_lock(&css_set_lock); | |
649 | /* Add reference counts and links from the new css_set. */ | |
7717f7ba PM |
650 | list_for_each_entry(link, &oldcg->cg_links, cg_link_list) { |
651 | struct cgroup *c = link->cgrp; | |
652 | if (c->root == cgrp->root) | |
653 | c = cgrp; | |
654 | link_css_set(&tmp_cg_links, res, c); | |
655 | } | |
817929ec PM |
656 | |
657 | BUG_ON(!list_empty(&tmp_cg_links)); | |
658 | ||
817929ec | 659 | css_set_count++; |
472b1053 LZ |
660 | |
661 | /* Add this cgroup group to the hash table */ | |
662 | hhead = css_set_hash(res->subsys); | |
663 | hlist_add_head(&res->hlist, hhead); | |
664 | ||
817929ec PM |
665 | write_unlock(&css_set_lock); |
666 | ||
667 | return res; | |
b4f48b63 PM |
668 | } |
669 | ||
7717f7ba PM |
670 | /* |
671 | * Return the cgroup for "task" from the given hierarchy. Must be | |
672 | * called with cgroup_mutex held. | |
673 | */ | |
674 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
675 | struct cgroupfs_root *root) | |
676 | { | |
677 | struct css_set *css; | |
678 | struct cgroup *res = NULL; | |
679 | ||
680 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); | |
681 | read_lock(&css_set_lock); | |
682 | /* | |
683 | * No need to lock the task - since we hold cgroup_mutex the | |
684 | * task can't change groups, so the only thing that can happen | |
685 | * is that it exits and its css is set back to init_css_set. | |
686 | */ | |
687 | css = task->cgroups; | |
688 | if (css == &init_css_set) { | |
689 | res = &root->top_cgroup; | |
690 | } else { | |
691 | struct cg_cgroup_link *link; | |
692 | list_for_each_entry(link, &css->cg_links, cg_link_list) { | |
693 | struct cgroup *c = link->cgrp; | |
694 | if (c->root == root) { | |
695 | res = c; | |
696 | break; | |
697 | } | |
698 | } | |
699 | } | |
700 | read_unlock(&css_set_lock); | |
701 | BUG_ON(!res); | |
702 | return res; | |
703 | } | |
704 | ||
ddbcc7e8 PM |
705 | /* |
706 | * There is one global cgroup mutex. We also require taking | |
707 | * task_lock() when dereferencing a task's cgroup subsys pointers. | |
708 | * See "The task_lock() exception", at the end of this comment. | |
709 | * | |
710 | * A task must hold cgroup_mutex to modify cgroups. | |
711 | * | |
712 | * Any task can increment and decrement the count field without lock. | |
713 | * So in general, code holding cgroup_mutex can't rely on the count | |
714 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 715 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
716 | * means that no tasks are currently attached, therefore there is no |
717 | * way a task attached to that cgroup can fork (the other way to | |
718 | * increment the count). So code holding cgroup_mutex can safely | |
719 | * assume that if the count is zero, it will stay zero. Similarly, if | |
720 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
721 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
722 | * needs that mutex. | |
723 | * | |
ddbcc7e8 PM |
724 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
725 | * (usually) take cgroup_mutex. These are the two most performance | |
726 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
727 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
728 | * is taken, and if the cgroup count is zero, a usermode call made | |
a043e3b2 LZ |
729 | * to the release agent with the name of the cgroup (path relative to |
730 | * the root of cgroup file system) as the argument. | |
ddbcc7e8 PM |
731 | * |
732 | * A cgroup can only be deleted if both its 'count' of using tasks | |
733 | * is zero, and its list of 'children' cgroups is empty. Since all | |
734 | * tasks in the system use _some_ cgroup, and since there is always at | |
735 | * least one task in the system (init, pid == 1), therefore, top_cgroup | |
736 | * always has either children cgroups and/or using tasks. So we don't | |
737 | * need a special hack to ensure that top_cgroup cannot be deleted. | |
738 | * | |
739 | * The task_lock() exception | |
740 | * | |
741 | * The need for this exception arises from the action of | |
956db3ca | 742 | * cgroup_attach_task(), which overwrites one tasks cgroup pointer with |
a043e3b2 | 743 | * another. It does so using cgroup_mutex, however there are |
ddbcc7e8 PM |
744 | * several performance critical places that need to reference |
745 | * task->cgroup without the expense of grabbing a system global | |
746 | * mutex. Therefore except as noted below, when dereferencing or, as | |
956db3ca | 747 | * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use |
ddbcc7e8 PM |
748 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in |
749 | * the task_struct routinely used for such matters. | |
750 | * | |
751 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 752 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
753 | */ |
754 | ||
ddbcc7e8 PM |
755 | /** |
756 | * cgroup_lock - lock out any changes to cgroup structures | |
757 | * | |
758 | */ | |
ddbcc7e8 PM |
759 | void cgroup_lock(void) |
760 | { | |
761 | mutex_lock(&cgroup_mutex); | |
762 | } | |
67523c48 | 763 | EXPORT_SYMBOL_GPL(cgroup_lock); |
ddbcc7e8 PM |
764 | |
765 | /** | |
766 | * cgroup_unlock - release lock on cgroup changes | |
767 | * | |
768 | * Undo the lock taken in a previous cgroup_lock() call. | |
769 | */ | |
ddbcc7e8 PM |
770 | void cgroup_unlock(void) |
771 | { | |
772 | mutex_unlock(&cgroup_mutex); | |
773 | } | |
67523c48 | 774 | EXPORT_SYMBOL_GPL(cgroup_unlock); |
ddbcc7e8 PM |
775 | |
776 | /* | |
777 | * A couple of forward declarations required, due to cyclic reference loop: | |
778 | * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> | |
779 | * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations | |
780 | * -> cgroup_mkdir. | |
781 | */ | |
782 | ||
18bb1db3 | 783 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode); |
c72a04e3 | 784 | static struct dentry *cgroup_lookup(struct inode *, struct dentry *, struct nameidata *); |
ddbcc7e8 | 785 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); |
bd89aabc | 786 | static int cgroup_populate_dir(struct cgroup *cgrp); |
6e1d5dcc | 787 | static const struct inode_operations cgroup_dir_inode_operations; |
828c0950 | 788 | static const struct file_operations proc_cgroupstats_operations; |
a424316c PM |
789 | |
790 | static struct backing_dev_info cgroup_backing_dev_info = { | |
d993831f | 791 | .name = "cgroup", |
e4ad08fe | 792 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
a424316c | 793 | }; |
ddbcc7e8 | 794 | |
38460b48 KH |
795 | static int alloc_css_id(struct cgroup_subsys *ss, |
796 | struct cgroup *parent, struct cgroup *child); | |
797 | ||
a5e7ed32 | 798 | static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) |
ddbcc7e8 PM |
799 | { |
800 | struct inode *inode = new_inode(sb); | |
ddbcc7e8 PM |
801 | |
802 | if (inode) { | |
85fe4025 | 803 | inode->i_ino = get_next_ino(); |
ddbcc7e8 | 804 | inode->i_mode = mode; |
76aac0e9 DH |
805 | inode->i_uid = current_fsuid(); |
806 | inode->i_gid = current_fsgid(); | |
ddbcc7e8 PM |
807 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
808 | inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; | |
809 | } | |
810 | return inode; | |
811 | } | |
812 | ||
4fca88c8 KH |
813 | /* |
814 | * Call subsys's pre_destroy handler. | |
815 | * This is called before css refcnt check. | |
816 | */ | |
ec64f515 | 817 | static int cgroup_call_pre_destroy(struct cgroup *cgrp) |
4fca88c8 KH |
818 | { |
819 | struct cgroup_subsys *ss; | |
ec64f515 KH |
820 | int ret = 0; |
821 | ||
4fca88c8 | 822 | for_each_subsys(cgrp->root, ss) |
ec64f515 | 823 | if (ss->pre_destroy) { |
761b3ef5 | 824 | ret = ss->pre_destroy(cgrp); |
ec64f515 | 825 | if (ret) |
4ab78683 | 826 | break; |
ec64f515 | 827 | } |
0dea1168 | 828 | |
ec64f515 | 829 | return ret; |
4fca88c8 KH |
830 | } |
831 | ||
ddbcc7e8 PM |
832 | static void cgroup_diput(struct dentry *dentry, struct inode *inode) |
833 | { | |
834 | /* is dentry a directory ? if so, kfree() associated cgroup */ | |
835 | if (S_ISDIR(inode->i_mode)) { | |
bd89aabc | 836 | struct cgroup *cgrp = dentry->d_fsdata; |
8dc4f3e1 | 837 | struct cgroup_subsys *ss; |
bd89aabc | 838 | BUG_ON(!(cgroup_is_removed(cgrp))); |
81a6a5cd PM |
839 | /* It's possible for external users to be holding css |
840 | * reference counts on a cgroup; css_put() needs to | |
841 | * be able to access the cgroup after decrementing | |
842 | * the reference count in order to know if it needs to | |
843 | * queue the cgroup to be handled by the release | |
844 | * agent */ | |
845 | synchronize_rcu(); | |
8dc4f3e1 PM |
846 | |
847 | mutex_lock(&cgroup_mutex); | |
848 | /* | |
849 | * Release the subsystem state objects. | |
850 | */ | |
75139b82 | 851 | for_each_subsys(cgrp->root, ss) |
761b3ef5 | 852 | ss->destroy(cgrp); |
8dc4f3e1 PM |
853 | |
854 | cgrp->root->number_of_cgroups--; | |
855 | mutex_unlock(&cgroup_mutex); | |
856 | ||
a47295e6 PM |
857 | /* |
858 | * Drop the active superblock reference that we took when we | |
859 | * created the cgroup | |
860 | */ | |
8dc4f3e1 PM |
861 | deactivate_super(cgrp->root->sb); |
862 | ||
72a8cb30 BB |
863 | /* |
864 | * if we're getting rid of the cgroup, refcount should ensure | |
865 | * that there are no pidlists left. | |
866 | */ | |
867 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
868 | ||
f2da1c40 | 869 | kfree_rcu(cgrp, rcu_head); |
ddbcc7e8 PM |
870 | } |
871 | iput(inode); | |
872 | } | |
873 | ||
c72a04e3 AV |
874 | static int cgroup_delete(const struct dentry *d) |
875 | { | |
876 | return 1; | |
877 | } | |
878 | ||
ddbcc7e8 PM |
879 | static void remove_dir(struct dentry *d) |
880 | { | |
881 | struct dentry *parent = dget(d->d_parent); | |
882 | ||
883 | d_delete(d); | |
884 | simple_rmdir(parent->d_inode, d); | |
885 | dput(parent); | |
886 | } | |
887 | ||
888 | static void cgroup_clear_directory(struct dentry *dentry) | |
889 | { | |
890 | struct list_head *node; | |
891 | ||
892 | BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); | |
2fd6b7f5 | 893 | spin_lock(&dentry->d_lock); |
ddbcc7e8 PM |
894 | node = dentry->d_subdirs.next; |
895 | while (node != &dentry->d_subdirs) { | |
896 | struct dentry *d = list_entry(node, struct dentry, d_u.d_child); | |
2fd6b7f5 NP |
897 | |
898 | spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); | |
ddbcc7e8 PM |
899 | list_del_init(node); |
900 | if (d->d_inode) { | |
901 | /* This should never be called on a cgroup | |
902 | * directory with child cgroups */ | |
903 | BUG_ON(d->d_inode->i_mode & S_IFDIR); | |
dc0474be | 904 | dget_dlock(d); |
2fd6b7f5 NP |
905 | spin_unlock(&d->d_lock); |
906 | spin_unlock(&dentry->d_lock); | |
ddbcc7e8 PM |
907 | d_delete(d); |
908 | simple_unlink(dentry->d_inode, d); | |
909 | dput(d); | |
2fd6b7f5 NP |
910 | spin_lock(&dentry->d_lock); |
911 | } else | |
912 | spin_unlock(&d->d_lock); | |
ddbcc7e8 PM |
913 | node = dentry->d_subdirs.next; |
914 | } | |
2fd6b7f5 | 915 | spin_unlock(&dentry->d_lock); |
ddbcc7e8 PM |
916 | } |
917 | ||
918 | /* | |
919 | * NOTE : the dentry must have been dget()'ed | |
920 | */ | |
921 | static void cgroup_d_remove_dir(struct dentry *dentry) | |
922 | { | |
2fd6b7f5 NP |
923 | struct dentry *parent; |
924 | ||
ddbcc7e8 PM |
925 | cgroup_clear_directory(dentry); |
926 | ||
2fd6b7f5 NP |
927 | parent = dentry->d_parent; |
928 | spin_lock(&parent->d_lock); | |
3ec762ad | 929 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
ddbcc7e8 | 930 | list_del_init(&dentry->d_u.d_child); |
2fd6b7f5 NP |
931 | spin_unlock(&dentry->d_lock); |
932 | spin_unlock(&parent->d_lock); | |
ddbcc7e8 PM |
933 | remove_dir(dentry); |
934 | } | |
935 | ||
ec64f515 KH |
936 | /* |
937 | * A queue for waiters to do rmdir() cgroup. A tasks will sleep when | |
938 | * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some | |
939 | * reference to css->refcnt. In general, this refcnt is expected to goes down | |
940 | * to zero, soon. | |
941 | * | |
88703267 | 942 | * CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex; |
ec64f515 | 943 | */ |
1c6c3fad | 944 | static DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq); |
ec64f515 | 945 | |
88703267 | 946 | static void cgroup_wakeup_rmdir_waiter(struct cgroup *cgrp) |
ec64f515 | 947 | { |
88703267 | 948 | if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags))) |
ec64f515 KH |
949 | wake_up_all(&cgroup_rmdir_waitq); |
950 | } | |
951 | ||
88703267 KH |
952 | void cgroup_exclude_rmdir(struct cgroup_subsys_state *css) |
953 | { | |
954 | css_get(css); | |
955 | } | |
956 | ||
957 | void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css) | |
958 | { | |
959 | cgroup_wakeup_rmdir_waiter(css->cgroup); | |
960 | css_put(css); | |
961 | } | |
962 | ||
aae8aab4 | 963 | /* |
cf5d5941 BB |
964 | * Call with cgroup_mutex held. Drops reference counts on modules, including |
965 | * any duplicate ones that parse_cgroupfs_options took. If this function | |
966 | * returns an error, no reference counts are touched. | |
aae8aab4 | 967 | */ |
ddbcc7e8 PM |
968 | static int rebind_subsystems(struct cgroupfs_root *root, |
969 | unsigned long final_bits) | |
970 | { | |
971 | unsigned long added_bits, removed_bits; | |
bd89aabc | 972 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
973 | int i; |
974 | ||
aae8aab4 | 975 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
e25e2cbb | 976 | BUG_ON(!mutex_is_locked(&cgroup_root_mutex)); |
aae8aab4 | 977 | |
ddbcc7e8 PM |
978 | removed_bits = root->actual_subsys_bits & ~final_bits; |
979 | added_bits = final_bits & ~root->actual_subsys_bits; | |
980 | /* Check that any added subsystems are currently free */ | |
981 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
8d53d55d | 982 | unsigned long bit = 1UL << i; |
ddbcc7e8 PM |
983 | struct cgroup_subsys *ss = subsys[i]; |
984 | if (!(bit & added_bits)) | |
985 | continue; | |
aae8aab4 BB |
986 | /* |
987 | * Nobody should tell us to do a subsys that doesn't exist: | |
988 | * parse_cgroupfs_options should catch that case and refcounts | |
989 | * ensure that subsystems won't disappear once selected. | |
990 | */ | |
991 | BUG_ON(ss == NULL); | |
ddbcc7e8 PM |
992 | if (ss->root != &rootnode) { |
993 | /* Subsystem isn't free */ | |
994 | return -EBUSY; | |
995 | } | |
996 | } | |
997 | ||
998 | /* Currently we don't handle adding/removing subsystems when | |
999 | * any child cgroups exist. This is theoretically supportable | |
1000 | * but involves complex error handling, so it's being left until | |
1001 | * later */ | |
307257cf | 1002 | if (root->number_of_cgroups > 1) |
ddbcc7e8 PM |
1003 | return -EBUSY; |
1004 | ||
1005 | /* Process each subsystem */ | |
1006 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1007 | struct cgroup_subsys *ss = subsys[i]; | |
1008 | unsigned long bit = 1UL << i; | |
1009 | if (bit & added_bits) { | |
1010 | /* We're binding this subsystem to this hierarchy */ | |
aae8aab4 | 1011 | BUG_ON(ss == NULL); |
bd89aabc | 1012 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
1013 | BUG_ON(!dummytop->subsys[i]); |
1014 | BUG_ON(dummytop->subsys[i]->cgroup != dummytop); | |
999cd8a4 | 1015 | mutex_lock(&ss->hierarchy_mutex); |
bd89aabc PM |
1016 | cgrp->subsys[i] = dummytop->subsys[i]; |
1017 | cgrp->subsys[i]->cgroup = cgrp; | |
33a68ac1 | 1018 | list_move(&ss->sibling, &root->subsys_list); |
b2aa30f7 | 1019 | ss->root = root; |
ddbcc7e8 | 1020 | if (ss->bind) |
761b3ef5 | 1021 | ss->bind(cgrp); |
999cd8a4 | 1022 | mutex_unlock(&ss->hierarchy_mutex); |
cf5d5941 | 1023 | /* refcount was already taken, and we're keeping it */ |
ddbcc7e8 PM |
1024 | } else if (bit & removed_bits) { |
1025 | /* We're removing this subsystem */ | |
aae8aab4 | 1026 | BUG_ON(ss == NULL); |
bd89aabc PM |
1027 | BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); |
1028 | BUG_ON(cgrp->subsys[i]->cgroup != cgrp); | |
999cd8a4 | 1029 | mutex_lock(&ss->hierarchy_mutex); |
ddbcc7e8 | 1030 | if (ss->bind) |
761b3ef5 | 1031 | ss->bind(dummytop); |
ddbcc7e8 | 1032 | dummytop->subsys[i]->cgroup = dummytop; |
bd89aabc | 1033 | cgrp->subsys[i] = NULL; |
b2aa30f7 | 1034 | subsys[i]->root = &rootnode; |
33a68ac1 | 1035 | list_move(&ss->sibling, &rootnode.subsys_list); |
999cd8a4 | 1036 | mutex_unlock(&ss->hierarchy_mutex); |
cf5d5941 BB |
1037 | /* subsystem is now free - drop reference on module */ |
1038 | module_put(ss->module); | |
ddbcc7e8 PM |
1039 | } else if (bit & final_bits) { |
1040 | /* Subsystem state should already exist */ | |
aae8aab4 | 1041 | BUG_ON(ss == NULL); |
bd89aabc | 1042 | BUG_ON(!cgrp->subsys[i]); |
cf5d5941 BB |
1043 | /* |
1044 | * a refcount was taken, but we already had one, so | |
1045 | * drop the extra reference. | |
1046 | */ | |
1047 | module_put(ss->module); | |
1048 | #ifdef CONFIG_MODULE_UNLOAD | |
1049 | BUG_ON(ss->module && !module_refcount(ss->module)); | |
1050 | #endif | |
ddbcc7e8 PM |
1051 | } else { |
1052 | /* Subsystem state shouldn't exist */ | |
bd89aabc | 1053 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
1054 | } |
1055 | } | |
1056 | root->subsys_bits = root->actual_subsys_bits = final_bits; | |
1057 | synchronize_rcu(); | |
1058 | ||
1059 | return 0; | |
1060 | } | |
1061 | ||
34c80b1d | 1062 | static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) |
ddbcc7e8 | 1063 | { |
34c80b1d | 1064 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; |
ddbcc7e8 PM |
1065 | struct cgroup_subsys *ss; |
1066 | ||
e25e2cbb | 1067 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1068 | for_each_subsys(root, ss) |
1069 | seq_printf(seq, ",%s", ss->name); | |
1070 | if (test_bit(ROOT_NOPREFIX, &root->flags)) | |
1071 | seq_puts(seq, ",noprefix"); | |
81a6a5cd PM |
1072 | if (strlen(root->release_agent_path)) |
1073 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
97978e6d DL |
1074 | if (clone_children(&root->top_cgroup)) |
1075 | seq_puts(seq, ",clone_children"); | |
c6d57f33 PM |
1076 | if (strlen(root->name)) |
1077 | seq_printf(seq, ",name=%s", root->name); | |
e25e2cbb | 1078 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1079 | return 0; |
1080 | } | |
1081 | ||
1082 | struct cgroup_sb_opts { | |
1083 | unsigned long subsys_bits; | |
1084 | unsigned long flags; | |
81a6a5cd | 1085 | char *release_agent; |
97978e6d | 1086 | bool clone_children; |
c6d57f33 | 1087 | char *name; |
2c6ab6d2 PM |
1088 | /* User explicitly requested empty subsystem */ |
1089 | bool none; | |
c6d57f33 PM |
1090 | |
1091 | struct cgroupfs_root *new_root; | |
2c6ab6d2 | 1092 | |
ddbcc7e8 PM |
1093 | }; |
1094 | ||
aae8aab4 BB |
1095 | /* |
1096 | * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call | |
cf5d5941 BB |
1097 | * with cgroup_mutex held to protect the subsys[] array. This function takes |
1098 | * refcounts on subsystems to be used, unless it returns error, in which case | |
1099 | * no refcounts are taken. | |
aae8aab4 | 1100 | */ |
cf5d5941 | 1101 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1102 | { |
32a8cf23 DL |
1103 | char *token, *o = data; |
1104 | bool all_ss = false, one_ss = false; | |
f9ab5b5b | 1105 | unsigned long mask = (unsigned long)-1; |
cf5d5941 BB |
1106 | int i; |
1107 | bool module_pin_failed = false; | |
f9ab5b5b | 1108 | |
aae8aab4 BB |
1109 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
1110 | ||
f9ab5b5b LZ |
1111 | #ifdef CONFIG_CPUSETS |
1112 | mask = ~(1UL << cpuset_subsys_id); | |
1113 | #endif | |
ddbcc7e8 | 1114 | |
c6d57f33 | 1115 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1116 | |
1117 | while ((token = strsep(&o, ",")) != NULL) { | |
1118 | if (!*token) | |
1119 | return -EINVAL; | |
32a8cf23 | 1120 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1121 | /* Explicitly have no subsystems */ |
1122 | opts->none = true; | |
32a8cf23 DL |
1123 | continue; |
1124 | } | |
1125 | if (!strcmp(token, "all")) { | |
1126 | /* Mutually exclusive option 'all' + subsystem name */ | |
1127 | if (one_ss) | |
1128 | return -EINVAL; | |
1129 | all_ss = true; | |
1130 | continue; | |
1131 | } | |
1132 | if (!strcmp(token, "noprefix")) { | |
ddbcc7e8 | 1133 | set_bit(ROOT_NOPREFIX, &opts->flags); |
32a8cf23 DL |
1134 | continue; |
1135 | } | |
1136 | if (!strcmp(token, "clone_children")) { | |
97978e6d | 1137 | opts->clone_children = true; |
32a8cf23 DL |
1138 | continue; |
1139 | } | |
1140 | if (!strncmp(token, "release_agent=", 14)) { | |
81a6a5cd PM |
1141 | /* Specifying two release agents is forbidden */ |
1142 | if (opts->release_agent) | |
1143 | return -EINVAL; | |
c6d57f33 | 1144 | opts->release_agent = |
e400c285 | 1145 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1146 | if (!opts->release_agent) |
1147 | return -ENOMEM; | |
32a8cf23 DL |
1148 | continue; |
1149 | } | |
1150 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1151 | const char *name = token + 5; |
1152 | /* Can't specify an empty name */ | |
1153 | if (!strlen(name)) | |
1154 | return -EINVAL; | |
1155 | /* Must match [\w.-]+ */ | |
1156 | for (i = 0; i < strlen(name); i++) { | |
1157 | char c = name[i]; | |
1158 | if (isalnum(c)) | |
1159 | continue; | |
1160 | if ((c == '.') || (c == '-') || (c == '_')) | |
1161 | continue; | |
1162 | return -EINVAL; | |
1163 | } | |
1164 | /* Specifying two names is forbidden */ | |
1165 | if (opts->name) | |
1166 | return -EINVAL; | |
1167 | opts->name = kstrndup(name, | |
e400c285 | 1168 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1169 | GFP_KERNEL); |
1170 | if (!opts->name) | |
1171 | return -ENOMEM; | |
32a8cf23 DL |
1172 | |
1173 | continue; | |
1174 | } | |
1175 | ||
1176 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1177 | struct cgroup_subsys *ss = subsys[i]; | |
1178 | if (ss == NULL) | |
1179 | continue; | |
1180 | if (strcmp(token, ss->name)) | |
1181 | continue; | |
1182 | if (ss->disabled) | |
1183 | continue; | |
1184 | ||
1185 | /* Mutually exclusive option 'all' + subsystem name */ | |
1186 | if (all_ss) | |
1187 | return -EINVAL; | |
1188 | set_bit(i, &opts->subsys_bits); | |
1189 | one_ss = true; | |
1190 | ||
1191 | break; | |
1192 | } | |
1193 | if (i == CGROUP_SUBSYS_COUNT) | |
1194 | return -ENOENT; | |
1195 | } | |
1196 | ||
1197 | /* | |
1198 | * If the 'all' option was specified select all the subsystems, | |
0d19ea86 LZ |
1199 | * otherwise if 'none', 'name=' and a subsystem name options |
1200 | * were not specified, let's default to 'all' | |
32a8cf23 | 1201 | */ |
0d19ea86 | 1202 | if (all_ss || (!one_ss && !opts->none && !opts->name)) { |
32a8cf23 DL |
1203 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
1204 | struct cgroup_subsys *ss = subsys[i]; | |
1205 | if (ss == NULL) | |
1206 | continue; | |
1207 | if (ss->disabled) | |
1208 | continue; | |
1209 | set_bit(i, &opts->subsys_bits); | |
ddbcc7e8 PM |
1210 | } |
1211 | } | |
1212 | ||
2c6ab6d2 PM |
1213 | /* Consistency checks */ |
1214 | ||
f9ab5b5b LZ |
1215 | /* |
1216 | * Option noprefix was introduced just for backward compatibility | |
1217 | * with the old cpuset, so we allow noprefix only if mounting just | |
1218 | * the cpuset subsystem. | |
1219 | */ | |
1220 | if (test_bit(ROOT_NOPREFIX, &opts->flags) && | |
1221 | (opts->subsys_bits & mask)) | |
1222 | return -EINVAL; | |
1223 | ||
2c6ab6d2 PM |
1224 | |
1225 | /* Can't specify "none" and some subsystems */ | |
1226 | if (opts->subsys_bits && opts->none) | |
1227 | return -EINVAL; | |
1228 | ||
1229 | /* | |
1230 | * We either have to specify by name or by subsystems. (So all | |
1231 | * empty hierarchies must have a name). | |
1232 | */ | |
c6d57f33 | 1233 | if (!opts->subsys_bits && !opts->name) |
ddbcc7e8 PM |
1234 | return -EINVAL; |
1235 | ||
cf5d5941 BB |
1236 | /* |
1237 | * Grab references on all the modules we'll need, so the subsystems | |
1238 | * don't dance around before rebind_subsystems attaches them. This may | |
1239 | * take duplicate reference counts on a subsystem that's already used, | |
1240 | * but rebind_subsystems handles this case. | |
1241 | */ | |
1242 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { | |
1243 | unsigned long bit = 1UL << i; | |
1244 | ||
1245 | if (!(bit & opts->subsys_bits)) | |
1246 | continue; | |
1247 | if (!try_module_get(subsys[i]->module)) { | |
1248 | module_pin_failed = true; | |
1249 | break; | |
1250 | } | |
1251 | } | |
1252 | if (module_pin_failed) { | |
1253 | /* | |
1254 | * oops, one of the modules was going away. this means that we | |
1255 | * raced with a module_delete call, and to the user this is | |
1256 | * essentially a "subsystem doesn't exist" case. | |
1257 | */ | |
1258 | for (i--; i >= CGROUP_BUILTIN_SUBSYS_COUNT; i--) { | |
1259 | /* drop refcounts only on the ones we took */ | |
1260 | unsigned long bit = 1UL << i; | |
1261 | ||
1262 | if (!(bit & opts->subsys_bits)) | |
1263 | continue; | |
1264 | module_put(subsys[i]->module); | |
1265 | } | |
1266 | return -ENOENT; | |
1267 | } | |
1268 | ||
ddbcc7e8 PM |
1269 | return 0; |
1270 | } | |
1271 | ||
cf5d5941 BB |
1272 | static void drop_parsed_module_refcounts(unsigned long subsys_bits) |
1273 | { | |
1274 | int i; | |
1275 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { | |
1276 | unsigned long bit = 1UL << i; | |
1277 | ||
1278 | if (!(bit & subsys_bits)) | |
1279 | continue; | |
1280 | module_put(subsys[i]->module); | |
1281 | } | |
1282 | } | |
1283 | ||
ddbcc7e8 PM |
1284 | static int cgroup_remount(struct super_block *sb, int *flags, char *data) |
1285 | { | |
1286 | int ret = 0; | |
1287 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1288 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
1289 | struct cgroup_sb_opts opts; |
1290 | ||
bd89aabc | 1291 | mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 | 1292 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1293 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1294 | |
1295 | /* See what subsystems are wanted */ | |
1296 | ret = parse_cgroupfs_options(data, &opts); | |
1297 | if (ret) | |
1298 | goto out_unlock; | |
1299 | ||
8b5a5a9d TH |
1300 | /* See feature-removal-schedule.txt */ |
1301 | if (opts.subsys_bits != root->actual_subsys_bits || opts.release_agent) | |
1302 | pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", | |
1303 | task_tgid_nr(current), current->comm); | |
1304 | ||
cf5d5941 BB |
1305 | /* Don't allow flags or name to change at remount */ |
1306 | if (opts.flags != root->flags || | |
1307 | (opts.name && strcmp(opts.name, root->name))) { | |
c6d57f33 | 1308 | ret = -EINVAL; |
cf5d5941 | 1309 | drop_parsed_module_refcounts(opts.subsys_bits); |
c6d57f33 PM |
1310 | goto out_unlock; |
1311 | } | |
1312 | ||
ddbcc7e8 | 1313 | ret = rebind_subsystems(root, opts.subsys_bits); |
cf5d5941 BB |
1314 | if (ret) { |
1315 | drop_parsed_module_refcounts(opts.subsys_bits); | |
0670e08b | 1316 | goto out_unlock; |
cf5d5941 | 1317 | } |
ddbcc7e8 | 1318 | |
ff4c8d50 TH |
1319 | /* clear out any existing files and repopulate subsystem files */ |
1320 | cgroup_clear_directory(cgrp->dentry); | |
0670e08b | 1321 | cgroup_populate_dir(cgrp); |
ddbcc7e8 | 1322 | |
81a6a5cd PM |
1323 | if (opts.release_agent) |
1324 | strcpy(root->release_agent_path, opts.release_agent); | |
ddbcc7e8 | 1325 | out_unlock: |
66bdc9cf | 1326 | kfree(opts.release_agent); |
c6d57f33 | 1327 | kfree(opts.name); |
e25e2cbb | 1328 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1329 | mutex_unlock(&cgroup_mutex); |
bd89aabc | 1330 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
1331 | return ret; |
1332 | } | |
1333 | ||
b87221de | 1334 | static const struct super_operations cgroup_ops = { |
ddbcc7e8 PM |
1335 | .statfs = simple_statfs, |
1336 | .drop_inode = generic_delete_inode, | |
1337 | .show_options = cgroup_show_options, | |
1338 | .remount_fs = cgroup_remount, | |
1339 | }; | |
1340 | ||
cc31edce PM |
1341 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1342 | { | |
1343 | INIT_LIST_HEAD(&cgrp->sibling); | |
1344 | INIT_LIST_HEAD(&cgrp->children); | |
1345 | INIT_LIST_HEAD(&cgrp->css_sets); | |
1346 | INIT_LIST_HEAD(&cgrp->release_list); | |
72a8cb30 BB |
1347 | INIT_LIST_HEAD(&cgrp->pidlists); |
1348 | mutex_init(&cgrp->pidlist_mutex); | |
0dea1168 KS |
1349 | INIT_LIST_HEAD(&cgrp->event_list); |
1350 | spin_lock_init(&cgrp->event_list_lock); | |
cc31edce | 1351 | } |
c6d57f33 | 1352 | |
ddbcc7e8 PM |
1353 | static void init_cgroup_root(struct cgroupfs_root *root) |
1354 | { | |
bd89aabc | 1355 | struct cgroup *cgrp = &root->top_cgroup; |
b0ca5a84 | 1356 | |
ddbcc7e8 PM |
1357 | INIT_LIST_HEAD(&root->subsys_list); |
1358 | INIT_LIST_HEAD(&root->root_list); | |
b0ca5a84 | 1359 | INIT_LIST_HEAD(&root->allcg_list); |
ddbcc7e8 | 1360 | root->number_of_cgroups = 1; |
bd89aabc PM |
1361 | cgrp->root = root; |
1362 | cgrp->top_cgroup = cgrp; | |
b0ca5a84 | 1363 | list_add_tail(&cgrp->allcg_node, &root->allcg_list); |
cc31edce | 1364 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 PM |
1365 | } |
1366 | ||
2c6ab6d2 PM |
1367 | static bool init_root_id(struct cgroupfs_root *root) |
1368 | { | |
1369 | int ret = 0; | |
1370 | ||
1371 | do { | |
1372 | if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL)) | |
1373 | return false; | |
1374 | spin_lock(&hierarchy_id_lock); | |
1375 | /* Try to allocate the next unused ID */ | |
1376 | ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id, | |
1377 | &root->hierarchy_id); | |
1378 | if (ret == -ENOSPC) | |
1379 | /* Try again starting from 0 */ | |
1380 | ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id); | |
1381 | if (!ret) { | |
1382 | next_hierarchy_id = root->hierarchy_id + 1; | |
1383 | } else if (ret != -EAGAIN) { | |
1384 | /* Can only get here if the 31-bit IDR is full ... */ | |
1385 | BUG_ON(ret); | |
1386 | } | |
1387 | spin_unlock(&hierarchy_id_lock); | |
1388 | } while (ret); | |
1389 | return true; | |
1390 | } | |
1391 | ||
ddbcc7e8 PM |
1392 | static int cgroup_test_super(struct super_block *sb, void *data) |
1393 | { | |
c6d57f33 | 1394 | struct cgroup_sb_opts *opts = data; |
ddbcc7e8 PM |
1395 | struct cgroupfs_root *root = sb->s_fs_info; |
1396 | ||
c6d57f33 PM |
1397 | /* If we asked for a name then it must match */ |
1398 | if (opts->name && strcmp(opts->name, root->name)) | |
1399 | return 0; | |
ddbcc7e8 | 1400 | |
2c6ab6d2 PM |
1401 | /* |
1402 | * If we asked for subsystems (or explicitly for no | |
1403 | * subsystems) then they must match | |
1404 | */ | |
1405 | if ((opts->subsys_bits || opts->none) | |
1406 | && (opts->subsys_bits != root->subsys_bits)) | |
ddbcc7e8 PM |
1407 | return 0; |
1408 | ||
1409 | return 1; | |
1410 | } | |
1411 | ||
c6d57f33 PM |
1412 | static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) |
1413 | { | |
1414 | struct cgroupfs_root *root; | |
1415 | ||
2c6ab6d2 | 1416 | if (!opts->subsys_bits && !opts->none) |
c6d57f33 PM |
1417 | return NULL; |
1418 | ||
1419 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
1420 | if (!root) | |
1421 | return ERR_PTR(-ENOMEM); | |
1422 | ||
2c6ab6d2 PM |
1423 | if (!init_root_id(root)) { |
1424 | kfree(root); | |
1425 | return ERR_PTR(-ENOMEM); | |
1426 | } | |
c6d57f33 | 1427 | init_cgroup_root(root); |
2c6ab6d2 | 1428 | |
c6d57f33 PM |
1429 | root->subsys_bits = opts->subsys_bits; |
1430 | root->flags = opts->flags; | |
1431 | if (opts->release_agent) | |
1432 | strcpy(root->release_agent_path, opts->release_agent); | |
1433 | if (opts->name) | |
1434 | strcpy(root->name, opts->name); | |
97978e6d DL |
1435 | if (opts->clone_children) |
1436 | set_bit(CGRP_CLONE_CHILDREN, &root->top_cgroup.flags); | |
c6d57f33 PM |
1437 | return root; |
1438 | } | |
1439 | ||
2c6ab6d2 PM |
1440 | static void cgroup_drop_root(struct cgroupfs_root *root) |
1441 | { | |
1442 | if (!root) | |
1443 | return; | |
1444 | ||
1445 | BUG_ON(!root->hierarchy_id); | |
1446 | spin_lock(&hierarchy_id_lock); | |
1447 | ida_remove(&hierarchy_ida, root->hierarchy_id); | |
1448 | spin_unlock(&hierarchy_id_lock); | |
1449 | kfree(root); | |
1450 | } | |
1451 | ||
ddbcc7e8 PM |
1452 | static int cgroup_set_super(struct super_block *sb, void *data) |
1453 | { | |
1454 | int ret; | |
c6d57f33 PM |
1455 | struct cgroup_sb_opts *opts = data; |
1456 | ||
1457 | /* If we don't have a new root, we can't set up a new sb */ | |
1458 | if (!opts->new_root) | |
1459 | return -EINVAL; | |
1460 | ||
2c6ab6d2 | 1461 | BUG_ON(!opts->subsys_bits && !opts->none); |
ddbcc7e8 PM |
1462 | |
1463 | ret = set_anon_super(sb, NULL); | |
1464 | if (ret) | |
1465 | return ret; | |
1466 | ||
c6d57f33 PM |
1467 | sb->s_fs_info = opts->new_root; |
1468 | opts->new_root->sb = sb; | |
ddbcc7e8 PM |
1469 | |
1470 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
1471 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
1472 | sb->s_magic = CGROUP_SUPER_MAGIC; | |
1473 | sb->s_op = &cgroup_ops; | |
1474 | ||
1475 | return 0; | |
1476 | } | |
1477 | ||
1478 | static int cgroup_get_rootdir(struct super_block *sb) | |
1479 | { | |
0df6a63f AV |
1480 | static const struct dentry_operations cgroup_dops = { |
1481 | .d_iput = cgroup_diput, | |
c72a04e3 | 1482 | .d_delete = cgroup_delete, |
0df6a63f AV |
1483 | }; |
1484 | ||
ddbcc7e8 PM |
1485 | struct inode *inode = |
1486 | cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); | |
ddbcc7e8 PM |
1487 | |
1488 | if (!inode) | |
1489 | return -ENOMEM; | |
1490 | ||
ddbcc7e8 PM |
1491 | inode->i_fop = &simple_dir_operations; |
1492 | inode->i_op = &cgroup_dir_inode_operations; | |
1493 | /* directories start off with i_nlink == 2 (for "." entry) */ | |
1494 | inc_nlink(inode); | |
48fde701 AV |
1495 | sb->s_root = d_make_root(inode); |
1496 | if (!sb->s_root) | |
ddbcc7e8 | 1497 | return -ENOMEM; |
0df6a63f AV |
1498 | /* for everything else we want ->d_op set */ |
1499 | sb->s_d_op = &cgroup_dops; | |
ddbcc7e8 PM |
1500 | return 0; |
1501 | } | |
1502 | ||
f7e83571 | 1503 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1504 | int flags, const char *unused_dev_name, |
f7e83571 | 1505 | void *data) |
ddbcc7e8 PM |
1506 | { |
1507 | struct cgroup_sb_opts opts; | |
c6d57f33 | 1508 | struct cgroupfs_root *root; |
ddbcc7e8 PM |
1509 | int ret = 0; |
1510 | struct super_block *sb; | |
c6d57f33 | 1511 | struct cgroupfs_root *new_root; |
e25e2cbb | 1512 | struct inode *inode; |
ddbcc7e8 PM |
1513 | |
1514 | /* First find the desired set of subsystems */ | |
aae8aab4 | 1515 | mutex_lock(&cgroup_mutex); |
ddbcc7e8 | 1516 | ret = parse_cgroupfs_options(data, &opts); |
aae8aab4 | 1517 | mutex_unlock(&cgroup_mutex); |
c6d57f33 PM |
1518 | if (ret) |
1519 | goto out_err; | |
ddbcc7e8 | 1520 | |
c6d57f33 PM |
1521 | /* |
1522 | * Allocate a new cgroup root. We may not need it if we're | |
1523 | * reusing an existing hierarchy. | |
1524 | */ | |
1525 | new_root = cgroup_root_from_opts(&opts); | |
1526 | if (IS_ERR(new_root)) { | |
1527 | ret = PTR_ERR(new_root); | |
cf5d5941 | 1528 | goto drop_modules; |
81a6a5cd | 1529 | } |
c6d57f33 | 1530 | opts.new_root = new_root; |
ddbcc7e8 | 1531 | |
c6d57f33 PM |
1532 | /* Locate an existing or new sb for this hierarchy */ |
1533 | sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts); | |
ddbcc7e8 | 1534 | if (IS_ERR(sb)) { |
c6d57f33 | 1535 | ret = PTR_ERR(sb); |
2c6ab6d2 | 1536 | cgroup_drop_root(opts.new_root); |
cf5d5941 | 1537 | goto drop_modules; |
ddbcc7e8 PM |
1538 | } |
1539 | ||
c6d57f33 PM |
1540 | root = sb->s_fs_info; |
1541 | BUG_ON(!root); | |
1542 | if (root == opts.new_root) { | |
1543 | /* We used the new root structure, so this is a new hierarchy */ | |
1544 | struct list_head tmp_cg_links; | |
c12f65d4 | 1545 | struct cgroup *root_cgrp = &root->top_cgroup; |
c6d57f33 | 1546 | struct cgroupfs_root *existing_root; |
2ce9738b | 1547 | const struct cred *cred; |
28fd5dfc | 1548 | int i; |
ddbcc7e8 PM |
1549 | |
1550 | BUG_ON(sb->s_root != NULL); | |
1551 | ||
1552 | ret = cgroup_get_rootdir(sb); | |
1553 | if (ret) | |
1554 | goto drop_new_super; | |
817929ec | 1555 | inode = sb->s_root->d_inode; |
ddbcc7e8 | 1556 | |
817929ec | 1557 | mutex_lock(&inode->i_mutex); |
ddbcc7e8 | 1558 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1559 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 | 1560 | |
e25e2cbb TH |
1561 | /* Check for name clashes with existing mounts */ |
1562 | ret = -EBUSY; | |
1563 | if (strlen(root->name)) | |
1564 | for_each_active_root(existing_root) | |
1565 | if (!strcmp(existing_root->name, root->name)) | |
1566 | goto unlock_drop; | |
c6d57f33 | 1567 | |
817929ec PM |
1568 | /* |
1569 | * We're accessing css_set_count without locking | |
1570 | * css_set_lock here, but that's OK - it can only be | |
1571 | * increased by someone holding cgroup_lock, and | |
1572 | * that's us. The worst that can happen is that we | |
1573 | * have some link structures left over | |
1574 | */ | |
1575 | ret = allocate_cg_links(css_set_count, &tmp_cg_links); | |
e25e2cbb TH |
1576 | if (ret) |
1577 | goto unlock_drop; | |
817929ec | 1578 | |
ddbcc7e8 PM |
1579 | ret = rebind_subsystems(root, root->subsys_bits); |
1580 | if (ret == -EBUSY) { | |
c6d57f33 | 1581 | free_cg_links(&tmp_cg_links); |
e25e2cbb | 1582 | goto unlock_drop; |
ddbcc7e8 | 1583 | } |
cf5d5941 BB |
1584 | /* |
1585 | * There must be no failure case after here, since rebinding | |
1586 | * takes care of subsystems' refcounts, which are explicitly | |
1587 | * dropped in the failure exit path. | |
1588 | */ | |
ddbcc7e8 PM |
1589 | |
1590 | /* EBUSY should be the only error here */ | |
1591 | BUG_ON(ret); | |
1592 | ||
1593 | list_add(&root->root_list, &roots); | |
817929ec | 1594 | root_count++; |
ddbcc7e8 | 1595 | |
c12f65d4 | 1596 | sb->s_root->d_fsdata = root_cgrp; |
ddbcc7e8 PM |
1597 | root->top_cgroup.dentry = sb->s_root; |
1598 | ||
817929ec PM |
1599 | /* Link the top cgroup in this hierarchy into all |
1600 | * the css_set objects */ | |
1601 | write_lock(&css_set_lock); | |
28fd5dfc LZ |
1602 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { |
1603 | struct hlist_head *hhead = &css_set_table[i]; | |
1604 | struct hlist_node *node; | |
817929ec | 1605 | struct css_set *cg; |
28fd5dfc | 1606 | |
c12f65d4 LZ |
1607 | hlist_for_each_entry(cg, node, hhead, hlist) |
1608 | link_css_set(&tmp_cg_links, cg, root_cgrp); | |
28fd5dfc | 1609 | } |
817929ec PM |
1610 | write_unlock(&css_set_lock); |
1611 | ||
1612 | free_cg_links(&tmp_cg_links); | |
1613 | ||
c12f65d4 LZ |
1614 | BUG_ON(!list_empty(&root_cgrp->sibling)); |
1615 | BUG_ON(!list_empty(&root_cgrp->children)); | |
ddbcc7e8 PM |
1616 | BUG_ON(root->number_of_cgroups != 1); |
1617 | ||
2ce9738b | 1618 | cred = override_creds(&init_cred); |
c12f65d4 | 1619 | cgroup_populate_dir(root_cgrp); |
2ce9738b | 1620 | revert_creds(cred); |
e25e2cbb | 1621 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1622 | mutex_unlock(&cgroup_mutex); |
34f77a90 | 1623 | mutex_unlock(&inode->i_mutex); |
c6d57f33 PM |
1624 | } else { |
1625 | /* | |
1626 | * We re-used an existing hierarchy - the new root (if | |
1627 | * any) is not needed | |
1628 | */ | |
2c6ab6d2 | 1629 | cgroup_drop_root(opts.new_root); |
cf5d5941 BB |
1630 | /* no subsys rebinding, so refcounts don't change */ |
1631 | drop_parsed_module_refcounts(opts.subsys_bits); | |
ddbcc7e8 PM |
1632 | } |
1633 | ||
c6d57f33 PM |
1634 | kfree(opts.release_agent); |
1635 | kfree(opts.name); | |
f7e83571 | 1636 | return dget(sb->s_root); |
ddbcc7e8 | 1637 | |
e25e2cbb TH |
1638 | unlock_drop: |
1639 | mutex_unlock(&cgroup_root_mutex); | |
1640 | mutex_unlock(&cgroup_mutex); | |
1641 | mutex_unlock(&inode->i_mutex); | |
ddbcc7e8 | 1642 | drop_new_super: |
6f5bbff9 | 1643 | deactivate_locked_super(sb); |
cf5d5941 BB |
1644 | drop_modules: |
1645 | drop_parsed_module_refcounts(opts.subsys_bits); | |
c6d57f33 PM |
1646 | out_err: |
1647 | kfree(opts.release_agent); | |
1648 | kfree(opts.name); | |
f7e83571 | 1649 | return ERR_PTR(ret); |
ddbcc7e8 PM |
1650 | } |
1651 | ||
1652 | static void cgroup_kill_sb(struct super_block *sb) { | |
1653 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1654 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 | 1655 | int ret; |
71cbb949 KM |
1656 | struct cg_cgroup_link *link; |
1657 | struct cg_cgroup_link *saved_link; | |
ddbcc7e8 PM |
1658 | |
1659 | BUG_ON(!root); | |
1660 | ||
1661 | BUG_ON(root->number_of_cgroups != 1); | |
bd89aabc PM |
1662 | BUG_ON(!list_empty(&cgrp->children)); |
1663 | BUG_ON(!list_empty(&cgrp->sibling)); | |
ddbcc7e8 PM |
1664 | |
1665 | mutex_lock(&cgroup_mutex); | |
e25e2cbb | 1666 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1667 | |
1668 | /* Rebind all subsystems back to the default hierarchy */ | |
1669 | ret = rebind_subsystems(root, 0); | |
1670 | /* Shouldn't be able to fail ... */ | |
1671 | BUG_ON(ret); | |
1672 | ||
817929ec PM |
1673 | /* |
1674 | * Release all the links from css_sets to this hierarchy's | |
1675 | * root cgroup | |
1676 | */ | |
1677 | write_lock(&css_set_lock); | |
71cbb949 KM |
1678 | |
1679 | list_for_each_entry_safe(link, saved_link, &cgrp->css_sets, | |
1680 | cgrp_link_list) { | |
817929ec | 1681 | list_del(&link->cg_link_list); |
bd89aabc | 1682 | list_del(&link->cgrp_link_list); |
817929ec PM |
1683 | kfree(link); |
1684 | } | |
1685 | write_unlock(&css_set_lock); | |
1686 | ||
839ec545 PM |
1687 | if (!list_empty(&root->root_list)) { |
1688 | list_del(&root->root_list); | |
1689 | root_count--; | |
1690 | } | |
e5f6a860 | 1691 | |
e25e2cbb | 1692 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1693 | mutex_unlock(&cgroup_mutex); |
1694 | ||
ddbcc7e8 | 1695 | kill_litter_super(sb); |
2c6ab6d2 | 1696 | cgroup_drop_root(root); |
ddbcc7e8 PM |
1697 | } |
1698 | ||
1699 | static struct file_system_type cgroup_fs_type = { | |
1700 | .name = "cgroup", | |
f7e83571 | 1701 | .mount = cgroup_mount, |
ddbcc7e8 PM |
1702 | .kill_sb = cgroup_kill_sb, |
1703 | }; | |
1704 | ||
676db4af GKH |
1705 | static struct kobject *cgroup_kobj; |
1706 | ||
bd89aabc | 1707 | static inline struct cgroup *__d_cgrp(struct dentry *dentry) |
ddbcc7e8 PM |
1708 | { |
1709 | return dentry->d_fsdata; | |
1710 | } | |
1711 | ||
1712 | static inline struct cftype *__d_cft(struct dentry *dentry) | |
1713 | { | |
1714 | return dentry->d_fsdata; | |
1715 | } | |
1716 | ||
a043e3b2 LZ |
1717 | /** |
1718 | * cgroup_path - generate the path of a cgroup | |
1719 | * @cgrp: the cgroup in question | |
1720 | * @buf: the buffer to write the path into | |
1721 | * @buflen: the length of the buffer | |
1722 | * | |
a47295e6 PM |
1723 | * Called with cgroup_mutex held or else with an RCU-protected cgroup |
1724 | * reference. Writes path of cgroup into buf. Returns 0 on success, | |
1725 | * -errno on error. | |
ddbcc7e8 | 1726 | */ |
bd89aabc | 1727 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) |
ddbcc7e8 PM |
1728 | { |
1729 | char *start; | |
9a9686b6 | 1730 | struct dentry *dentry = rcu_dereference_check(cgrp->dentry, |
9a9686b6 | 1731 | cgroup_lock_is_held()); |
ddbcc7e8 | 1732 | |
a47295e6 | 1733 | if (!dentry || cgrp == dummytop) { |
ddbcc7e8 PM |
1734 | /* |
1735 | * Inactive subsystems have no dentry for their root | |
1736 | * cgroup | |
1737 | */ | |
1738 | strcpy(buf, "/"); | |
1739 | return 0; | |
1740 | } | |
1741 | ||
1742 | start = buf + buflen; | |
1743 | ||
1744 | *--start = '\0'; | |
1745 | for (;;) { | |
a47295e6 | 1746 | int len = dentry->d_name.len; |
9a9686b6 | 1747 | |
ddbcc7e8 PM |
1748 | if ((start -= len) < buf) |
1749 | return -ENAMETOOLONG; | |
9a9686b6 | 1750 | memcpy(start, dentry->d_name.name, len); |
bd89aabc PM |
1751 | cgrp = cgrp->parent; |
1752 | if (!cgrp) | |
ddbcc7e8 | 1753 | break; |
9a9686b6 LZ |
1754 | |
1755 | dentry = rcu_dereference_check(cgrp->dentry, | |
9a9686b6 | 1756 | cgroup_lock_is_held()); |
bd89aabc | 1757 | if (!cgrp->parent) |
ddbcc7e8 PM |
1758 | continue; |
1759 | if (--start < buf) | |
1760 | return -ENAMETOOLONG; | |
1761 | *start = '/'; | |
1762 | } | |
1763 | memmove(buf, start, buf + buflen - start); | |
1764 | return 0; | |
1765 | } | |
67523c48 | 1766 | EXPORT_SYMBOL_GPL(cgroup_path); |
ddbcc7e8 | 1767 | |
2f7ee569 TH |
1768 | /* |
1769 | * Control Group taskset | |
1770 | */ | |
134d3373 TH |
1771 | struct task_and_cgroup { |
1772 | struct task_struct *task; | |
1773 | struct cgroup *cgrp; | |
61d1d219 | 1774 | struct css_set *cg; |
134d3373 TH |
1775 | }; |
1776 | ||
2f7ee569 TH |
1777 | struct cgroup_taskset { |
1778 | struct task_and_cgroup single; | |
1779 | struct flex_array *tc_array; | |
1780 | int tc_array_len; | |
1781 | int idx; | |
1782 | struct cgroup *cur_cgrp; | |
1783 | }; | |
1784 | ||
1785 | /** | |
1786 | * cgroup_taskset_first - reset taskset and return the first task | |
1787 | * @tset: taskset of interest | |
1788 | * | |
1789 | * @tset iteration is initialized and the first task is returned. | |
1790 | */ | |
1791 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
1792 | { | |
1793 | if (tset->tc_array) { | |
1794 | tset->idx = 0; | |
1795 | return cgroup_taskset_next(tset); | |
1796 | } else { | |
1797 | tset->cur_cgrp = tset->single.cgrp; | |
1798 | return tset->single.task; | |
1799 | } | |
1800 | } | |
1801 | EXPORT_SYMBOL_GPL(cgroup_taskset_first); | |
1802 | ||
1803 | /** | |
1804 | * cgroup_taskset_next - iterate to the next task in taskset | |
1805 | * @tset: taskset of interest | |
1806 | * | |
1807 | * Return the next task in @tset. Iteration must have been initialized | |
1808 | * with cgroup_taskset_first(). | |
1809 | */ | |
1810 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
1811 | { | |
1812 | struct task_and_cgroup *tc; | |
1813 | ||
1814 | if (!tset->tc_array || tset->idx >= tset->tc_array_len) | |
1815 | return NULL; | |
1816 | ||
1817 | tc = flex_array_get(tset->tc_array, tset->idx++); | |
1818 | tset->cur_cgrp = tc->cgrp; | |
1819 | return tc->task; | |
1820 | } | |
1821 | EXPORT_SYMBOL_GPL(cgroup_taskset_next); | |
1822 | ||
1823 | /** | |
1824 | * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task | |
1825 | * @tset: taskset of interest | |
1826 | * | |
1827 | * Return the cgroup for the current (last returned) task of @tset. This | |
1828 | * function must be preceded by either cgroup_taskset_first() or | |
1829 | * cgroup_taskset_next(). | |
1830 | */ | |
1831 | struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset) | |
1832 | { | |
1833 | return tset->cur_cgrp; | |
1834 | } | |
1835 | EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup); | |
1836 | ||
1837 | /** | |
1838 | * cgroup_taskset_size - return the number of tasks in taskset | |
1839 | * @tset: taskset of interest | |
1840 | */ | |
1841 | int cgroup_taskset_size(struct cgroup_taskset *tset) | |
1842 | { | |
1843 | return tset->tc_array ? tset->tc_array_len : 1; | |
1844 | } | |
1845 | EXPORT_SYMBOL_GPL(cgroup_taskset_size); | |
1846 | ||
1847 | ||
74a1166d BB |
1848 | /* |
1849 | * cgroup_task_migrate - move a task from one cgroup to another. | |
1850 | * | |
1851 | * 'guarantee' is set if the caller promises that a new css_set for the task | |
1852 | * will already exist. If not set, this function might sleep, and can fail with | |
cd3d0952 | 1853 | * -ENOMEM. Must be called with cgroup_mutex and threadgroup locked. |
74a1166d | 1854 | */ |
61d1d219 MSB |
1855 | static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, |
1856 | struct task_struct *tsk, struct css_set *newcg) | |
74a1166d BB |
1857 | { |
1858 | struct css_set *oldcg; | |
74a1166d BB |
1859 | |
1860 | /* | |
026085ef MSB |
1861 | * We are synchronized through threadgroup_lock() against PF_EXITING |
1862 | * setting such that we can't race against cgroup_exit() changing the | |
1863 | * css_set to init_css_set and dropping the old one. | |
74a1166d | 1864 | */ |
c84cdf75 | 1865 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
74a1166d | 1866 | oldcg = tsk->cgroups; |
74a1166d | 1867 | |
74a1166d | 1868 | task_lock(tsk); |
74a1166d BB |
1869 | rcu_assign_pointer(tsk->cgroups, newcg); |
1870 | task_unlock(tsk); | |
1871 | ||
1872 | /* Update the css_set linked lists if we're using them */ | |
1873 | write_lock(&css_set_lock); | |
1874 | if (!list_empty(&tsk->cg_list)) | |
1875 | list_move(&tsk->cg_list, &newcg->tasks); | |
1876 | write_unlock(&css_set_lock); | |
1877 | ||
1878 | /* | |
1879 | * We just gained a reference on oldcg by taking it from the task. As | |
1880 | * trading it for newcg is protected by cgroup_mutex, we're safe to drop | |
1881 | * it here; it will be freed under RCU. | |
1882 | */ | |
1883 | put_css_set(oldcg); | |
1884 | ||
1885 | set_bit(CGRP_RELEASABLE, &oldcgrp->flags); | |
74a1166d BB |
1886 | } |
1887 | ||
a043e3b2 LZ |
1888 | /** |
1889 | * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' | |
1890 | * @cgrp: the cgroup the task is attaching to | |
1891 | * @tsk: the task to be attached | |
bbcb81d0 | 1892 | * |
cd3d0952 TH |
1893 | * Call with cgroup_mutex and threadgroup locked. May take task_lock of |
1894 | * @tsk during call. | |
bbcb81d0 | 1895 | */ |
956db3ca | 1896 | int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) |
bbcb81d0 | 1897 | { |
8f121918 | 1898 | int retval = 0; |
2468c723 | 1899 | struct cgroup_subsys *ss, *failed_ss = NULL; |
bd89aabc | 1900 | struct cgroup *oldcgrp; |
bd89aabc | 1901 | struct cgroupfs_root *root = cgrp->root; |
2f7ee569 | 1902 | struct cgroup_taskset tset = { }; |
61d1d219 | 1903 | struct css_set *newcg; |
bbcb81d0 | 1904 | |
cd3d0952 TH |
1905 | /* @tsk either already exited or can't exit until the end */ |
1906 | if (tsk->flags & PF_EXITING) | |
1907 | return -ESRCH; | |
bbcb81d0 PM |
1908 | |
1909 | /* Nothing to do if the task is already in that cgroup */ | |
7717f7ba | 1910 | oldcgrp = task_cgroup_from_root(tsk, root); |
bd89aabc | 1911 | if (cgrp == oldcgrp) |
bbcb81d0 PM |
1912 | return 0; |
1913 | ||
2f7ee569 TH |
1914 | tset.single.task = tsk; |
1915 | tset.single.cgrp = oldcgrp; | |
1916 | ||
bbcb81d0 PM |
1917 | for_each_subsys(root, ss) { |
1918 | if (ss->can_attach) { | |
761b3ef5 | 1919 | retval = ss->can_attach(cgrp, &tset); |
2468c723 DN |
1920 | if (retval) { |
1921 | /* | |
1922 | * Remember on which subsystem the can_attach() | |
1923 | * failed, so that we only call cancel_attach() | |
1924 | * against the subsystems whose can_attach() | |
1925 | * succeeded. (See below) | |
1926 | */ | |
1927 | failed_ss = ss; | |
1928 | goto out; | |
1929 | } | |
bbcb81d0 PM |
1930 | } |
1931 | } | |
1932 | ||
61d1d219 MSB |
1933 | newcg = find_css_set(tsk->cgroups, cgrp); |
1934 | if (!newcg) { | |
1935 | retval = -ENOMEM; | |
2468c723 | 1936 | goto out; |
61d1d219 MSB |
1937 | } |
1938 | ||
1939 | cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg); | |
817929ec | 1940 | |
bbcb81d0 | 1941 | for_each_subsys(root, ss) { |
e18f6318 | 1942 | if (ss->attach) |
761b3ef5 | 1943 | ss->attach(cgrp, &tset); |
bbcb81d0 | 1944 | } |
74a1166d | 1945 | |
bbcb81d0 | 1946 | synchronize_rcu(); |
ec64f515 KH |
1947 | |
1948 | /* | |
1949 | * wake up rmdir() waiter. the rmdir should fail since the cgroup | |
1950 | * is no longer empty. | |
1951 | */ | |
88703267 | 1952 | cgroup_wakeup_rmdir_waiter(cgrp); |
2468c723 DN |
1953 | out: |
1954 | if (retval) { | |
1955 | for_each_subsys(root, ss) { | |
1956 | if (ss == failed_ss) | |
1957 | /* | |
1958 | * This subsystem was the one that failed the | |
1959 | * can_attach() check earlier, so we don't need | |
1960 | * to call cancel_attach() against it or any | |
1961 | * remaining subsystems. | |
1962 | */ | |
1963 | break; | |
1964 | if (ss->cancel_attach) | |
761b3ef5 | 1965 | ss->cancel_attach(cgrp, &tset); |
2468c723 DN |
1966 | } |
1967 | } | |
1968 | return retval; | |
bbcb81d0 PM |
1969 | } |
1970 | ||
d7926ee3 | 1971 | /** |
31583bb0 MT |
1972 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' |
1973 | * @from: attach to all cgroups of a given task | |
d7926ee3 SS |
1974 | * @tsk: the task to be attached |
1975 | */ | |
31583bb0 | 1976 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) |
d7926ee3 SS |
1977 | { |
1978 | struct cgroupfs_root *root; | |
d7926ee3 SS |
1979 | int retval = 0; |
1980 | ||
1981 | cgroup_lock(); | |
1982 | for_each_active_root(root) { | |
31583bb0 MT |
1983 | struct cgroup *from_cg = task_cgroup_from_root(from, root); |
1984 | ||
1985 | retval = cgroup_attach_task(from_cg, tsk); | |
d7926ee3 SS |
1986 | if (retval) |
1987 | break; | |
1988 | } | |
1989 | cgroup_unlock(); | |
1990 | ||
1991 | return retval; | |
1992 | } | |
31583bb0 | 1993 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); |
d7926ee3 | 1994 | |
74a1166d BB |
1995 | /** |
1996 | * cgroup_attach_proc - attach all threads in a threadgroup to a cgroup | |
1997 | * @cgrp: the cgroup to attach to | |
1998 | * @leader: the threadgroup leader task_struct of the group to be attached | |
1999 | * | |
257058ae TH |
2000 | * Call holding cgroup_mutex and the group_rwsem of the leader. Will take |
2001 | * task_lock of each thread in leader's threadgroup individually in turn. | |
74a1166d | 2002 | */ |
1c6c3fad | 2003 | static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) |
74a1166d BB |
2004 | { |
2005 | int retval, i, group_size; | |
2006 | struct cgroup_subsys *ss, *failed_ss = NULL; | |
74a1166d | 2007 | /* guaranteed to be initialized later, but the compiler needs this */ |
74a1166d BB |
2008 | struct cgroupfs_root *root = cgrp->root; |
2009 | /* threadgroup list cursor and array */ | |
2010 | struct task_struct *tsk; | |
134d3373 | 2011 | struct task_and_cgroup *tc; |
d846687d | 2012 | struct flex_array *group; |
2f7ee569 | 2013 | struct cgroup_taskset tset = { }; |
74a1166d BB |
2014 | |
2015 | /* | |
2016 | * step 0: in order to do expensive, possibly blocking operations for | |
2017 | * every thread, we cannot iterate the thread group list, since it needs | |
2018 | * rcu or tasklist locked. instead, build an array of all threads in the | |
257058ae TH |
2019 | * group - group_rwsem prevents new threads from appearing, and if |
2020 | * threads exit, this will just be an over-estimate. | |
74a1166d BB |
2021 | */ |
2022 | group_size = get_nr_threads(leader); | |
d846687d | 2023 | /* flex_array supports very large thread-groups better than kmalloc. */ |
134d3373 | 2024 | group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL); |
74a1166d BB |
2025 | if (!group) |
2026 | return -ENOMEM; | |
d846687d BB |
2027 | /* pre-allocate to guarantee space while iterating in rcu read-side. */ |
2028 | retval = flex_array_prealloc(group, 0, group_size - 1, GFP_KERNEL); | |
2029 | if (retval) | |
2030 | goto out_free_group_list; | |
74a1166d | 2031 | |
74a1166d BB |
2032 | tsk = leader; |
2033 | i = 0; | |
fb5d2b4c MSB |
2034 | /* |
2035 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
2036 | * already PF_EXITING could be freed from underneath us unless we | |
2037 | * take an rcu_read_lock. | |
2038 | */ | |
2039 | rcu_read_lock(); | |
74a1166d | 2040 | do { |
134d3373 TH |
2041 | struct task_and_cgroup ent; |
2042 | ||
cd3d0952 TH |
2043 | /* @tsk either already exited or can't exit until the end */ |
2044 | if (tsk->flags & PF_EXITING) | |
2045 | continue; | |
2046 | ||
74a1166d BB |
2047 | /* as per above, nr_threads may decrease, but not increase. */ |
2048 | BUG_ON(i >= group_size); | |
134d3373 TH |
2049 | ent.task = tsk; |
2050 | ent.cgrp = task_cgroup_from_root(tsk, root); | |
892a2b90 MSB |
2051 | /* nothing to do if this task is already in the cgroup */ |
2052 | if (ent.cgrp == cgrp) | |
2053 | continue; | |
61d1d219 MSB |
2054 | /* |
2055 | * saying GFP_ATOMIC has no effect here because we did prealloc | |
2056 | * earlier, but it's good form to communicate our expectations. | |
2057 | */ | |
134d3373 | 2058 | retval = flex_array_put(group, i, &ent, GFP_ATOMIC); |
d846687d | 2059 | BUG_ON(retval != 0); |
74a1166d BB |
2060 | i++; |
2061 | } while_each_thread(leader, tsk); | |
fb5d2b4c | 2062 | rcu_read_unlock(); |
74a1166d BB |
2063 | /* remember the number of threads in the array for later. */ |
2064 | group_size = i; | |
2f7ee569 TH |
2065 | tset.tc_array = group; |
2066 | tset.tc_array_len = group_size; | |
74a1166d | 2067 | |
134d3373 TH |
2068 | /* methods shouldn't be called if no task is actually migrating */ |
2069 | retval = 0; | |
892a2b90 | 2070 | if (!group_size) |
b07ef774 | 2071 | goto out_free_group_list; |
134d3373 | 2072 | |
74a1166d BB |
2073 | /* |
2074 | * step 1: check that we can legitimately attach to the cgroup. | |
2075 | */ | |
2076 | for_each_subsys(root, ss) { | |
2077 | if (ss->can_attach) { | |
761b3ef5 | 2078 | retval = ss->can_attach(cgrp, &tset); |
74a1166d BB |
2079 | if (retval) { |
2080 | failed_ss = ss; | |
2081 | goto out_cancel_attach; | |
2082 | } | |
2083 | } | |
74a1166d BB |
2084 | } |
2085 | ||
2086 | /* | |
2087 | * step 2: make sure css_sets exist for all threads to be migrated. | |
2088 | * we use find_css_set, which allocates a new one if necessary. | |
2089 | */ | |
74a1166d | 2090 | for (i = 0; i < group_size; i++) { |
134d3373 | 2091 | tc = flex_array_get(group, i); |
61d1d219 MSB |
2092 | tc->cg = find_css_set(tc->task->cgroups, cgrp); |
2093 | if (!tc->cg) { | |
2094 | retval = -ENOMEM; | |
2095 | goto out_put_css_set_refs; | |
74a1166d BB |
2096 | } |
2097 | } | |
2098 | ||
2099 | /* | |
494c167c TH |
2100 | * step 3: now that we're guaranteed success wrt the css_sets, |
2101 | * proceed to move all tasks to the new cgroup. There are no | |
2102 | * failure cases after here, so this is the commit point. | |
74a1166d | 2103 | */ |
74a1166d | 2104 | for (i = 0; i < group_size; i++) { |
134d3373 | 2105 | tc = flex_array_get(group, i); |
61d1d219 | 2106 | cgroup_task_migrate(cgrp, tc->cgrp, tc->task, tc->cg); |
74a1166d BB |
2107 | } |
2108 | /* nothing is sensitive to fork() after this point. */ | |
2109 | ||
2110 | /* | |
494c167c | 2111 | * step 4: do subsystem attach callbacks. |
74a1166d BB |
2112 | */ |
2113 | for_each_subsys(root, ss) { | |
2114 | if (ss->attach) | |
761b3ef5 | 2115 | ss->attach(cgrp, &tset); |
74a1166d BB |
2116 | } |
2117 | ||
2118 | /* | |
2119 | * step 5: success! and cleanup | |
2120 | */ | |
2121 | synchronize_rcu(); | |
2122 | cgroup_wakeup_rmdir_waiter(cgrp); | |
2123 | retval = 0; | |
61d1d219 MSB |
2124 | out_put_css_set_refs: |
2125 | if (retval) { | |
2126 | for (i = 0; i < group_size; i++) { | |
2127 | tc = flex_array_get(group, i); | |
2128 | if (!tc->cg) | |
2129 | break; | |
2130 | put_css_set(tc->cg); | |
2131 | } | |
74a1166d BB |
2132 | } |
2133 | out_cancel_attach: | |
74a1166d BB |
2134 | if (retval) { |
2135 | for_each_subsys(root, ss) { | |
494c167c | 2136 | if (ss == failed_ss) |
74a1166d | 2137 | break; |
74a1166d | 2138 | if (ss->cancel_attach) |
761b3ef5 | 2139 | ss->cancel_attach(cgrp, &tset); |
74a1166d BB |
2140 | } |
2141 | } | |
74a1166d | 2142 | out_free_group_list: |
d846687d | 2143 | flex_array_free(group); |
74a1166d BB |
2144 | return retval; |
2145 | } | |
2146 | ||
2147 | /* | |
2148 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 TH |
2149 | * function to attach either it or all tasks in its threadgroup. Will lock |
2150 | * cgroup_mutex and threadgroup; may take task_lock of task. | |
bbcb81d0 | 2151 | */ |
74a1166d | 2152 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) |
bbcb81d0 | 2153 | { |
bbcb81d0 | 2154 | struct task_struct *tsk; |
c69e8d9c | 2155 | const struct cred *cred = current_cred(), *tcred; |
bbcb81d0 PM |
2156 | int ret; |
2157 | ||
74a1166d BB |
2158 | if (!cgroup_lock_live_group(cgrp)) |
2159 | return -ENODEV; | |
2160 | ||
b78949eb MSB |
2161 | retry_find_task: |
2162 | rcu_read_lock(); | |
bbcb81d0 | 2163 | if (pid) { |
73507f33 | 2164 | tsk = find_task_by_vpid(pid); |
74a1166d BB |
2165 | if (!tsk) { |
2166 | rcu_read_unlock(); | |
b78949eb MSB |
2167 | ret= -ESRCH; |
2168 | goto out_unlock_cgroup; | |
bbcb81d0 | 2169 | } |
74a1166d BB |
2170 | /* |
2171 | * even if we're attaching all tasks in the thread group, we | |
2172 | * only need to check permissions on one of them. | |
2173 | */ | |
c69e8d9c DH |
2174 | tcred = __task_cred(tsk); |
2175 | if (cred->euid && | |
2176 | cred->euid != tcred->uid && | |
2177 | cred->euid != tcred->suid) { | |
2178 | rcu_read_unlock(); | |
b78949eb MSB |
2179 | ret = -EACCES; |
2180 | goto out_unlock_cgroup; | |
bbcb81d0 | 2181 | } |
b78949eb MSB |
2182 | } else |
2183 | tsk = current; | |
cd3d0952 TH |
2184 | |
2185 | if (threadgroup) | |
b78949eb MSB |
2186 | tsk = tsk->group_leader; |
2187 | get_task_struct(tsk); | |
2188 | rcu_read_unlock(); | |
2189 | ||
2190 | threadgroup_lock(tsk); | |
2191 | if (threadgroup) { | |
2192 | if (!thread_group_leader(tsk)) { | |
2193 | /* | |
2194 | * a race with de_thread from another thread's exec() | |
2195 | * may strip us of our leadership, if this happens, | |
2196 | * there is no choice but to throw this task away and | |
2197 | * try again; this is | |
2198 | * "double-double-toil-and-trouble-check locking". | |
2199 | */ | |
2200 | threadgroup_unlock(tsk); | |
2201 | put_task_struct(tsk); | |
2202 | goto retry_find_task; | |
2203 | } | |
74a1166d | 2204 | ret = cgroup_attach_proc(cgrp, tsk); |
b78949eb | 2205 | } else |
74a1166d | 2206 | ret = cgroup_attach_task(cgrp, tsk); |
cd3d0952 TH |
2207 | threadgroup_unlock(tsk); |
2208 | ||
bbcb81d0 | 2209 | put_task_struct(tsk); |
b78949eb | 2210 | out_unlock_cgroup: |
74a1166d | 2211 | cgroup_unlock(); |
bbcb81d0 PM |
2212 | return ret; |
2213 | } | |
2214 | ||
af351026 | 2215 | static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) |
74a1166d BB |
2216 | { |
2217 | return attach_task_by_pid(cgrp, pid, false); | |
2218 | } | |
2219 | ||
2220 | static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid) | |
af351026 | 2221 | { |
b78949eb | 2222 | return attach_task_by_pid(cgrp, tgid, true); |
af351026 PM |
2223 | } |
2224 | ||
e788e066 PM |
2225 | /** |
2226 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
2227 | * @cgrp: the cgroup to be checked for liveness | |
2228 | * | |
84eea842 PM |
2229 | * On success, returns true; the lock should be later released with |
2230 | * cgroup_unlock(). On failure returns false with no lock held. | |
e788e066 | 2231 | */ |
84eea842 | 2232 | bool cgroup_lock_live_group(struct cgroup *cgrp) |
e788e066 PM |
2233 | { |
2234 | mutex_lock(&cgroup_mutex); | |
2235 | if (cgroup_is_removed(cgrp)) { | |
2236 | mutex_unlock(&cgroup_mutex); | |
2237 | return false; | |
2238 | } | |
2239 | return true; | |
2240 | } | |
67523c48 | 2241 | EXPORT_SYMBOL_GPL(cgroup_lock_live_group); |
e788e066 PM |
2242 | |
2243 | static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, | |
2244 | const char *buffer) | |
2245 | { | |
2246 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); | |
f4a2589f EK |
2247 | if (strlen(buffer) >= PATH_MAX) |
2248 | return -EINVAL; | |
e788e066 PM |
2249 | if (!cgroup_lock_live_group(cgrp)) |
2250 | return -ENODEV; | |
e25e2cbb | 2251 | mutex_lock(&cgroup_root_mutex); |
e788e066 | 2252 | strcpy(cgrp->root->release_agent_path, buffer); |
e25e2cbb | 2253 | mutex_unlock(&cgroup_root_mutex); |
84eea842 | 2254 | cgroup_unlock(); |
e788e066 PM |
2255 | return 0; |
2256 | } | |
2257 | ||
2258 | static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, | |
2259 | struct seq_file *seq) | |
2260 | { | |
2261 | if (!cgroup_lock_live_group(cgrp)) | |
2262 | return -ENODEV; | |
2263 | seq_puts(seq, cgrp->root->release_agent_path); | |
2264 | seq_putc(seq, '\n'); | |
84eea842 | 2265 | cgroup_unlock(); |
e788e066 PM |
2266 | return 0; |
2267 | } | |
2268 | ||
84eea842 PM |
2269 | /* A buffer size big enough for numbers or short strings */ |
2270 | #define CGROUP_LOCAL_BUFFER_SIZE 64 | |
2271 | ||
e73d2c61 | 2272 | static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, |
f4c753b7 PM |
2273 | struct file *file, |
2274 | const char __user *userbuf, | |
2275 | size_t nbytes, loff_t *unused_ppos) | |
355e0c48 | 2276 | { |
84eea842 | 2277 | char buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
355e0c48 | 2278 | int retval = 0; |
355e0c48 PM |
2279 | char *end; |
2280 | ||
2281 | if (!nbytes) | |
2282 | return -EINVAL; | |
2283 | if (nbytes >= sizeof(buffer)) | |
2284 | return -E2BIG; | |
2285 | if (copy_from_user(buffer, userbuf, nbytes)) | |
2286 | return -EFAULT; | |
2287 | ||
2288 | buffer[nbytes] = 0; /* nul-terminate */ | |
e73d2c61 | 2289 | if (cft->write_u64) { |
478988d3 | 2290 | u64 val = simple_strtoull(strstrip(buffer), &end, 0); |
e73d2c61 PM |
2291 | if (*end) |
2292 | return -EINVAL; | |
2293 | retval = cft->write_u64(cgrp, cft, val); | |
2294 | } else { | |
478988d3 | 2295 | s64 val = simple_strtoll(strstrip(buffer), &end, 0); |
e73d2c61 PM |
2296 | if (*end) |
2297 | return -EINVAL; | |
2298 | retval = cft->write_s64(cgrp, cft, val); | |
2299 | } | |
355e0c48 PM |
2300 | if (!retval) |
2301 | retval = nbytes; | |
2302 | return retval; | |
2303 | } | |
2304 | ||
db3b1497 PM |
2305 | static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, |
2306 | struct file *file, | |
2307 | const char __user *userbuf, | |
2308 | size_t nbytes, loff_t *unused_ppos) | |
2309 | { | |
84eea842 | 2310 | char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
db3b1497 PM |
2311 | int retval = 0; |
2312 | size_t max_bytes = cft->max_write_len; | |
2313 | char *buffer = local_buffer; | |
2314 | ||
2315 | if (!max_bytes) | |
2316 | max_bytes = sizeof(local_buffer) - 1; | |
2317 | if (nbytes >= max_bytes) | |
2318 | return -E2BIG; | |
2319 | /* Allocate a dynamic buffer if we need one */ | |
2320 | if (nbytes >= sizeof(local_buffer)) { | |
2321 | buffer = kmalloc(nbytes + 1, GFP_KERNEL); | |
2322 | if (buffer == NULL) | |
2323 | return -ENOMEM; | |
2324 | } | |
5a3eb9f6 LZ |
2325 | if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { |
2326 | retval = -EFAULT; | |
2327 | goto out; | |
2328 | } | |
db3b1497 PM |
2329 | |
2330 | buffer[nbytes] = 0; /* nul-terminate */ | |
478988d3 | 2331 | retval = cft->write_string(cgrp, cft, strstrip(buffer)); |
db3b1497 PM |
2332 | if (!retval) |
2333 | retval = nbytes; | |
5a3eb9f6 | 2334 | out: |
db3b1497 PM |
2335 | if (buffer != local_buffer) |
2336 | kfree(buffer); | |
2337 | return retval; | |
2338 | } | |
2339 | ||
ddbcc7e8 PM |
2340 | static ssize_t cgroup_file_write(struct file *file, const char __user *buf, |
2341 | size_t nbytes, loff_t *ppos) | |
2342 | { | |
2343 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 2344 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 2345 | |
75139b82 | 2346 | if (cgroup_is_removed(cgrp)) |
ddbcc7e8 | 2347 | return -ENODEV; |
355e0c48 | 2348 | if (cft->write) |
bd89aabc | 2349 | return cft->write(cgrp, cft, file, buf, nbytes, ppos); |
e73d2c61 PM |
2350 | if (cft->write_u64 || cft->write_s64) |
2351 | return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); | |
db3b1497 PM |
2352 | if (cft->write_string) |
2353 | return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); | |
d447ea2f PE |
2354 | if (cft->trigger) { |
2355 | int ret = cft->trigger(cgrp, (unsigned int)cft->private); | |
2356 | return ret ? ret : nbytes; | |
2357 | } | |
355e0c48 | 2358 | return -EINVAL; |
ddbcc7e8 PM |
2359 | } |
2360 | ||
f4c753b7 PM |
2361 | static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, |
2362 | struct file *file, | |
2363 | char __user *buf, size_t nbytes, | |
2364 | loff_t *ppos) | |
ddbcc7e8 | 2365 | { |
84eea842 | 2366 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
f4c753b7 | 2367 | u64 val = cft->read_u64(cgrp, cft); |
ddbcc7e8 PM |
2368 | int len = sprintf(tmp, "%llu\n", (unsigned long long) val); |
2369 | ||
2370 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2371 | } | |
2372 | ||
e73d2c61 PM |
2373 | static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft, |
2374 | struct file *file, | |
2375 | char __user *buf, size_t nbytes, | |
2376 | loff_t *ppos) | |
2377 | { | |
84eea842 | 2378 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
e73d2c61 PM |
2379 | s64 val = cft->read_s64(cgrp, cft); |
2380 | int len = sprintf(tmp, "%lld\n", (long long) val); | |
2381 | ||
2382 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2383 | } | |
2384 | ||
ddbcc7e8 PM |
2385 | static ssize_t cgroup_file_read(struct file *file, char __user *buf, |
2386 | size_t nbytes, loff_t *ppos) | |
2387 | { | |
2388 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 2389 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 2390 | |
75139b82 | 2391 | if (cgroup_is_removed(cgrp)) |
ddbcc7e8 PM |
2392 | return -ENODEV; |
2393 | ||
2394 | if (cft->read) | |
bd89aabc | 2395 | return cft->read(cgrp, cft, file, buf, nbytes, ppos); |
f4c753b7 PM |
2396 | if (cft->read_u64) |
2397 | return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos); | |
e73d2c61 PM |
2398 | if (cft->read_s64) |
2399 | return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos); | |
ddbcc7e8 PM |
2400 | return -EINVAL; |
2401 | } | |
2402 | ||
91796569 PM |
2403 | /* |
2404 | * seqfile ops/methods for returning structured data. Currently just | |
2405 | * supports string->u64 maps, but can be extended in future. | |
2406 | */ | |
2407 | ||
2408 | struct cgroup_seqfile_state { | |
2409 | struct cftype *cft; | |
2410 | struct cgroup *cgroup; | |
2411 | }; | |
2412 | ||
2413 | static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) | |
2414 | { | |
2415 | struct seq_file *sf = cb->state; | |
2416 | return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); | |
2417 | } | |
2418 | ||
2419 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) | |
2420 | { | |
2421 | struct cgroup_seqfile_state *state = m->private; | |
2422 | struct cftype *cft = state->cft; | |
29486df3 SH |
2423 | if (cft->read_map) { |
2424 | struct cgroup_map_cb cb = { | |
2425 | .fill = cgroup_map_add, | |
2426 | .state = m, | |
2427 | }; | |
2428 | return cft->read_map(state->cgroup, cft, &cb); | |
2429 | } | |
2430 | return cft->read_seq_string(state->cgroup, cft, m); | |
91796569 PM |
2431 | } |
2432 | ||
96930a63 | 2433 | static int cgroup_seqfile_release(struct inode *inode, struct file *file) |
91796569 PM |
2434 | { |
2435 | struct seq_file *seq = file->private_data; | |
2436 | kfree(seq->private); | |
2437 | return single_release(inode, file); | |
2438 | } | |
2439 | ||
828c0950 | 2440 | static const struct file_operations cgroup_seqfile_operations = { |
91796569 | 2441 | .read = seq_read, |
e788e066 | 2442 | .write = cgroup_file_write, |
91796569 PM |
2443 | .llseek = seq_lseek, |
2444 | .release = cgroup_seqfile_release, | |
2445 | }; | |
2446 | ||
ddbcc7e8 PM |
2447 | static int cgroup_file_open(struct inode *inode, struct file *file) |
2448 | { | |
2449 | int err; | |
2450 | struct cftype *cft; | |
2451 | ||
2452 | err = generic_file_open(inode, file); | |
2453 | if (err) | |
2454 | return err; | |
ddbcc7e8 | 2455 | cft = __d_cft(file->f_dentry); |
75139b82 | 2456 | |
29486df3 | 2457 | if (cft->read_map || cft->read_seq_string) { |
91796569 PM |
2458 | struct cgroup_seqfile_state *state = |
2459 | kzalloc(sizeof(*state), GFP_USER); | |
2460 | if (!state) | |
2461 | return -ENOMEM; | |
2462 | state->cft = cft; | |
2463 | state->cgroup = __d_cgrp(file->f_dentry->d_parent); | |
2464 | file->f_op = &cgroup_seqfile_operations; | |
2465 | err = single_open(file, cgroup_seqfile_show, state); | |
2466 | if (err < 0) | |
2467 | kfree(state); | |
2468 | } else if (cft->open) | |
ddbcc7e8 PM |
2469 | err = cft->open(inode, file); |
2470 | else | |
2471 | err = 0; | |
2472 | ||
2473 | return err; | |
2474 | } | |
2475 | ||
2476 | static int cgroup_file_release(struct inode *inode, struct file *file) | |
2477 | { | |
2478 | struct cftype *cft = __d_cft(file->f_dentry); | |
2479 | if (cft->release) | |
2480 | return cft->release(inode, file); | |
2481 | return 0; | |
2482 | } | |
2483 | ||
2484 | /* | |
2485 | * cgroup_rename - Only allow simple rename of directories in place. | |
2486 | */ | |
2487 | static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2488 | struct inode *new_dir, struct dentry *new_dentry) | |
2489 | { | |
2490 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) | |
2491 | return -ENOTDIR; | |
2492 | if (new_dentry->d_inode) | |
2493 | return -EEXIST; | |
2494 | if (old_dir != new_dir) | |
2495 | return -EIO; | |
2496 | return simple_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2497 | } | |
2498 | ||
828c0950 | 2499 | static const struct file_operations cgroup_file_operations = { |
ddbcc7e8 PM |
2500 | .read = cgroup_file_read, |
2501 | .write = cgroup_file_write, | |
2502 | .llseek = generic_file_llseek, | |
2503 | .open = cgroup_file_open, | |
2504 | .release = cgroup_file_release, | |
2505 | }; | |
2506 | ||
6e1d5dcc | 2507 | static const struct inode_operations cgroup_dir_inode_operations = { |
c72a04e3 | 2508 | .lookup = cgroup_lookup, |
ddbcc7e8 PM |
2509 | .mkdir = cgroup_mkdir, |
2510 | .rmdir = cgroup_rmdir, | |
2511 | .rename = cgroup_rename, | |
2512 | }; | |
2513 | ||
c72a04e3 AV |
2514 | static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) |
2515 | { | |
2516 | if (dentry->d_name.len > NAME_MAX) | |
2517 | return ERR_PTR(-ENAMETOOLONG); | |
2518 | d_add(dentry, NULL); | |
2519 | return NULL; | |
2520 | } | |
2521 | ||
0dea1168 KS |
2522 | /* |
2523 | * Check if a file is a control file | |
2524 | */ | |
2525 | static inline struct cftype *__file_cft(struct file *file) | |
2526 | { | |
2527 | if (file->f_dentry->d_inode->i_fop != &cgroup_file_operations) | |
2528 | return ERR_PTR(-EINVAL); | |
2529 | return __d_cft(file->f_dentry); | |
2530 | } | |
2531 | ||
a5e7ed32 | 2532 | static int cgroup_create_file(struct dentry *dentry, umode_t mode, |
5adcee1d NP |
2533 | struct super_block *sb) |
2534 | { | |
ddbcc7e8 PM |
2535 | struct inode *inode; |
2536 | ||
2537 | if (!dentry) | |
2538 | return -ENOENT; | |
2539 | if (dentry->d_inode) | |
2540 | return -EEXIST; | |
2541 | ||
2542 | inode = cgroup_new_inode(mode, sb); | |
2543 | if (!inode) | |
2544 | return -ENOMEM; | |
2545 | ||
2546 | if (S_ISDIR(mode)) { | |
2547 | inode->i_op = &cgroup_dir_inode_operations; | |
2548 | inode->i_fop = &simple_dir_operations; | |
2549 | ||
2550 | /* start off with i_nlink == 2 (for "." entry) */ | |
2551 | inc_nlink(inode); | |
2552 | ||
2553 | /* start with the directory inode held, so that we can | |
2554 | * populate it without racing with another mkdir */ | |
817929ec | 2555 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); |
ddbcc7e8 PM |
2556 | } else if (S_ISREG(mode)) { |
2557 | inode->i_size = 0; | |
2558 | inode->i_fop = &cgroup_file_operations; | |
2559 | } | |
ddbcc7e8 PM |
2560 | d_instantiate(dentry, inode); |
2561 | dget(dentry); /* Extra count - pin the dentry in core */ | |
2562 | return 0; | |
2563 | } | |
2564 | ||
2565 | /* | |
a043e3b2 LZ |
2566 | * cgroup_create_dir - create a directory for an object. |
2567 | * @cgrp: the cgroup we create the directory for. It must have a valid | |
2568 | * ->parent field. And we are going to fill its ->dentry field. | |
2569 | * @dentry: dentry of the new cgroup | |
2570 | * @mode: mode to set on new directory. | |
ddbcc7e8 | 2571 | */ |
bd89aabc | 2572 | static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry, |
a5e7ed32 | 2573 | umode_t mode) |
ddbcc7e8 PM |
2574 | { |
2575 | struct dentry *parent; | |
2576 | int error = 0; | |
2577 | ||
bd89aabc PM |
2578 | parent = cgrp->parent->dentry; |
2579 | error = cgroup_create_file(dentry, S_IFDIR | mode, cgrp->root->sb); | |
ddbcc7e8 | 2580 | if (!error) { |
bd89aabc | 2581 | dentry->d_fsdata = cgrp; |
ddbcc7e8 | 2582 | inc_nlink(parent->d_inode); |
a47295e6 | 2583 | rcu_assign_pointer(cgrp->dentry, dentry); |
ddbcc7e8 PM |
2584 | dget(dentry); |
2585 | } | |
2586 | dput(dentry); | |
2587 | ||
2588 | return error; | |
2589 | } | |
2590 | ||
099fca32 LZ |
2591 | /** |
2592 | * cgroup_file_mode - deduce file mode of a control file | |
2593 | * @cft: the control file in question | |
2594 | * | |
2595 | * returns cft->mode if ->mode is not 0 | |
2596 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
2597 | * returns S_IRUGO if it has only a read handler | |
2598 | * returns S_IWUSR if it has only a write hander | |
2599 | */ | |
a5e7ed32 | 2600 | static umode_t cgroup_file_mode(const struct cftype *cft) |
099fca32 | 2601 | { |
a5e7ed32 | 2602 | umode_t mode = 0; |
099fca32 LZ |
2603 | |
2604 | if (cft->mode) | |
2605 | return cft->mode; | |
2606 | ||
2607 | if (cft->read || cft->read_u64 || cft->read_s64 || | |
2608 | cft->read_map || cft->read_seq_string) | |
2609 | mode |= S_IRUGO; | |
2610 | ||
2611 | if (cft->write || cft->write_u64 || cft->write_s64 || | |
2612 | cft->write_string || cft->trigger) | |
2613 | mode |= S_IWUSR; | |
2614 | ||
2615 | return mode; | |
2616 | } | |
2617 | ||
bd89aabc | 2618 | int cgroup_add_file(struct cgroup *cgrp, |
ddbcc7e8 PM |
2619 | struct cgroup_subsys *subsys, |
2620 | const struct cftype *cft) | |
2621 | { | |
bd89aabc | 2622 | struct dentry *dir = cgrp->dentry; |
ddbcc7e8 PM |
2623 | struct dentry *dentry; |
2624 | int error; | |
a5e7ed32 | 2625 | umode_t mode; |
ddbcc7e8 PM |
2626 | |
2627 | char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; | |
bd89aabc | 2628 | if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) { |
ddbcc7e8 PM |
2629 | strcpy(name, subsys->name); |
2630 | strcat(name, "."); | |
2631 | } | |
2632 | strcat(name, cft->name); | |
2633 | BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); | |
2634 | dentry = lookup_one_len(name, dir, strlen(name)); | |
2635 | if (!IS_ERR(dentry)) { | |
099fca32 LZ |
2636 | mode = cgroup_file_mode(cft); |
2637 | error = cgroup_create_file(dentry, mode | S_IFREG, | |
bd89aabc | 2638 | cgrp->root->sb); |
ddbcc7e8 PM |
2639 | if (!error) |
2640 | dentry->d_fsdata = (void *)cft; | |
2641 | dput(dentry); | |
2642 | } else | |
2643 | error = PTR_ERR(dentry); | |
2644 | return error; | |
2645 | } | |
e6a1105b | 2646 | EXPORT_SYMBOL_GPL(cgroup_add_file); |
ddbcc7e8 | 2647 | |
bd89aabc | 2648 | int cgroup_add_files(struct cgroup *cgrp, |
ddbcc7e8 PM |
2649 | struct cgroup_subsys *subsys, |
2650 | const struct cftype cft[], | |
2651 | int count) | |
2652 | { | |
2653 | int i, err; | |
2654 | for (i = 0; i < count; i++) { | |
bd89aabc | 2655 | err = cgroup_add_file(cgrp, subsys, &cft[i]); |
ddbcc7e8 PM |
2656 | if (err) |
2657 | return err; | |
2658 | } | |
2659 | return 0; | |
2660 | } | |
e6a1105b | 2661 | EXPORT_SYMBOL_GPL(cgroup_add_files); |
ddbcc7e8 | 2662 | |
a043e3b2 LZ |
2663 | /** |
2664 | * cgroup_task_count - count the number of tasks in a cgroup. | |
2665 | * @cgrp: the cgroup in question | |
2666 | * | |
2667 | * Return the number of tasks in the cgroup. | |
2668 | */ | |
bd89aabc | 2669 | int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
2670 | { |
2671 | int count = 0; | |
71cbb949 | 2672 | struct cg_cgroup_link *link; |
817929ec PM |
2673 | |
2674 | read_lock(&css_set_lock); | |
71cbb949 | 2675 | list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) { |
146aa1bd | 2676 | count += atomic_read(&link->cg->refcount); |
817929ec PM |
2677 | } |
2678 | read_unlock(&css_set_lock); | |
bbcb81d0 PM |
2679 | return count; |
2680 | } | |
2681 | ||
817929ec PM |
2682 | /* |
2683 | * Advance a list_head iterator. The iterator should be positioned at | |
2684 | * the start of a css_set | |
2685 | */ | |
bd89aabc | 2686 | static void cgroup_advance_iter(struct cgroup *cgrp, |
7717f7ba | 2687 | struct cgroup_iter *it) |
817929ec PM |
2688 | { |
2689 | struct list_head *l = it->cg_link; | |
2690 | struct cg_cgroup_link *link; | |
2691 | struct css_set *cg; | |
2692 | ||
2693 | /* Advance to the next non-empty css_set */ | |
2694 | do { | |
2695 | l = l->next; | |
bd89aabc | 2696 | if (l == &cgrp->css_sets) { |
817929ec PM |
2697 | it->cg_link = NULL; |
2698 | return; | |
2699 | } | |
bd89aabc | 2700 | link = list_entry(l, struct cg_cgroup_link, cgrp_link_list); |
817929ec PM |
2701 | cg = link->cg; |
2702 | } while (list_empty(&cg->tasks)); | |
2703 | it->cg_link = l; | |
2704 | it->task = cg->tasks.next; | |
2705 | } | |
2706 | ||
31a7df01 CW |
2707 | /* |
2708 | * To reduce the fork() overhead for systems that are not actually | |
2709 | * using their cgroups capability, we don't maintain the lists running | |
2710 | * through each css_set to its tasks until we see the list actually | |
2711 | * used - in other words after the first call to cgroup_iter_start(). | |
31a7df01 | 2712 | */ |
3df91fe3 | 2713 | static void cgroup_enable_task_cg_lists(void) |
31a7df01 CW |
2714 | { |
2715 | struct task_struct *p, *g; | |
2716 | write_lock(&css_set_lock); | |
2717 | use_task_css_set_links = 1; | |
3ce3230a FW |
2718 | /* |
2719 | * We need tasklist_lock because RCU is not safe against | |
2720 | * while_each_thread(). Besides, a forking task that has passed | |
2721 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
2722 | * is not guaranteed to have its child immediately visible in the | |
2723 | * tasklist if we walk through it with RCU. | |
2724 | */ | |
2725 | read_lock(&tasklist_lock); | |
31a7df01 CW |
2726 | do_each_thread(g, p) { |
2727 | task_lock(p); | |
0e04388f LZ |
2728 | /* |
2729 | * We should check if the process is exiting, otherwise | |
2730 | * it will race with cgroup_exit() in that the list | |
2731 | * entry won't be deleted though the process has exited. | |
2732 | */ | |
2733 | if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) | |
31a7df01 CW |
2734 | list_add(&p->cg_list, &p->cgroups->tasks); |
2735 | task_unlock(p); | |
2736 | } while_each_thread(g, p); | |
3ce3230a | 2737 | read_unlock(&tasklist_lock); |
31a7df01 CW |
2738 | write_unlock(&css_set_lock); |
2739 | } | |
2740 | ||
bd89aabc | 2741 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) |
c6ca5750 | 2742 | __acquires(css_set_lock) |
817929ec PM |
2743 | { |
2744 | /* | |
2745 | * The first time anyone tries to iterate across a cgroup, | |
2746 | * we need to enable the list linking each css_set to its | |
2747 | * tasks, and fix up all existing tasks. | |
2748 | */ | |
31a7df01 CW |
2749 | if (!use_task_css_set_links) |
2750 | cgroup_enable_task_cg_lists(); | |
2751 | ||
817929ec | 2752 | read_lock(&css_set_lock); |
bd89aabc PM |
2753 | it->cg_link = &cgrp->css_sets; |
2754 | cgroup_advance_iter(cgrp, it); | |
817929ec PM |
2755 | } |
2756 | ||
bd89aabc | 2757 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
817929ec PM |
2758 | struct cgroup_iter *it) |
2759 | { | |
2760 | struct task_struct *res; | |
2761 | struct list_head *l = it->task; | |
2019f634 | 2762 | struct cg_cgroup_link *link; |
817929ec PM |
2763 | |
2764 | /* If the iterator cg is NULL, we have no tasks */ | |
2765 | if (!it->cg_link) | |
2766 | return NULL; | |
2767 | res = list_entry(l, struct task_struct, cg_list); | |
2768 | /* Advance iterator to find next entry */ | |
2769 | l = l->next; | |
2019f634 LJ |
2770 | link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list); |
2771 | if (l == &link->cg->tasks) { | |
817929ec PM |
2772 | /* We reached the end of this task list - move on to |
2773 | * the next cg_cgroup_link */ | |
bd89aabc | 2774 | cgroup_advance_iter(cgrp, it); |
817929ec PM |
2775 | } else { |
2776 | it->task = l; | |
2777 | } | |
2778 | return res; | |
2779 | } | |
2780 | ||
bd89aabc | 2781 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it) |
c6ca5750 | 2782 | __releases(css_set_lock) |
817929ec PM |
2783 | { |
2784 | read_unlock(&css_set_lock); | |
2785 | } | |
2786 | ||
31a7df01 CW |
2787 | static inline int started_after_time(struct task_struct *t1, |
2788 | struct timespec *time, | |
2789 | struct task_struct *t2) | |
2790 | { | |
2791 | int start_diff = timespec_compare(&t1->start_time, time); | |
2792 | if (start_diff > 0) { | |
2793 | return 1; | |
2794 | } else if (start_diff < 0) { | |
2795 | return 0; | |
2796 | } else { | |
2797 | /* | |
2798 | * Arbitrarily, if two processes started at the same | |
2799 | * time, we'll say that the lower pointer value | |
2800 | * started first. Note that t2 may have exited by now | |
2801 | * so this may not be a valid pointer any longer, but | |
2802 | * that's fine - it still serves to distinguish | |
2803 | * between two tasks started (effectively) simultaneously. | |
2804 | */ | |
2805 | return t1 > t2; | |
2806 | } | |
2807 | } | |
2808 | ||
2809 | /* | |
2810 | * This function is a callback from heap_insert() and is used to order | |
2811 | * the heap. | |
2812 | * In this case we order the heap in descending task start time. | |
2813 | */ | |
2814 | static inline int started_after(void *p1, void *p2) | |
2815 | { | |
2816 | struct task_struct *t1 = p1; | |
2817 | struct task_struct *t2 = p2; | |
2818 | return started_after_time(t1, &t2->start_time, t2); | |
2819 | } | |
2820 | ||
2821 | /** | |
2822 | * cgroup_scan_tasks - iterate though all the tasks in a cgroup | |
2823 | * @scan: struct cgroup_scanner containing arguments for the scan | |
2824 | * | |
2825 | * Arguments include pointers to callback functions test_task() and | |
2826 | * process_task(). | |
2827 | * Iterate through all the tasks in a cgroup, calling test_task() for each, | |
2828 | * and if it returns true, call process_task() for it also. | |
2829 | * The test_task pointer may be NULL, meaning always true (select all tasks). | |
2830 | * Effectively duplicates cgroup_iter_{start,next,end}() | |
2831 | * but does not lock css_set_lock for the call to process_task(). | |
2832 | * The struct cgroup_scanner may be embedded in any structure of the caller's | |
2833 | * creation. | |
2834 | * It is guaranteed that process_task() will act on every task that | |
2835 | * is a member of the cgroup for the duration of this call. This | |
2836 | * function may or may not call process_task() for tasks that exit | |
2837 | * or move to a different cgroup during the call, or are forked or | |
2838 | * move into the cgroup during the call. | |
2839 | * | |
2840 | * Note that test_task() may be called with locks held, and may in some | |
2841 | * situations be called multiple times for the same task, so it should | |
2842 | * be cheap. | |
2843 | * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been | |
2844 | * pre-allocated and will be used for heap operations (and its "gt" member will | |
2845 | * be overwritten), else a temporary heap will be used (allocation of which | |
2846 | * may cause this function to fail). | |
2847 | */ | |
2848 | int cgroup_scan_tasks(struct cgroup_scanner *scan) | |
2849 | { | |
2850 | int retval, i; | |
2851 | struct cgroup_iter it; | |
2852 | struct task_struct *p, *dropped; | |
2853 | /* Never dereference latest_task, since it's not refcounted */ | |
2854 | struct task_struct *latest_task = NULL; | |
2855 | struct ptr_heap tmp_heap; | |
2856 | struct ptr_heap *heap; | |
2857 | struct timespec latest_time = { 0, 0 }; | |
2858 | ||
2859 | if (scan->heap) { | |
2860 | /* The caller supplied our heap and pre-allocated its memory */ | |
2861 | heap = scan->heap; | |
2862 | heap->gt = &started_after; | |
2863 | } else { | |
2864 | /* We need to allocate our own heap memory */ | |
2865 | heap = &tmp_heap; | |
2866 | retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); | |
2867 | if (retval) | |
2868 | /* cannot allocate the heap */ | |
2869 | return retval; | |
2870 | } | |
2871 | ||
2872 | again: | |
2873 | /* | |
2874 | * Scan tasks in the cgroup, using the scanner's "test_task" callback | |
2875 | * to determine which are of interest, and using the scanner's | |
2876 | * "process_task" callback to process any of them that need an update. | |
2877 | * Since we don't want to hold any locks during the task updates, | |
2878 | * gather tasks to be processed in a heap structure. | |
2879 | * The heap is sorted by descending task start time. | |
2880 | * If the statically-sized heap fills up, we overflow tasks that | |
2881 | * started later, and in future iterations only consider tasks that | |
2882 | * started after the latest task in the previous pass. This | |
2883 | * guarantees forward progress and that we don't miss any tasks. | |
2884 | */ | |
2885 | heap->size = 0; | |
2886 | cgroup_iter_start(scan->cg, &it); | |
2887 | while ((p = cgroup_iter_next(scan->cg, &it))) { | |
2888 | /* | |
2889 | * Only affect tasks that qualify per the caller's callback, | |
2890 | * if he provided one | |
2891 | */ | |
2892 | if (scan->test_task && !scan->test_task(p, scan)) | |
2893 | continue; | |
2894 | /* | |
2895 | * Only process tasks that started after the last task | |
2896 | * we processed | |
2897 | */ | |
2898 | if (!started_after_time(p, &latest_time, latest_task)) | |
2899 | continue; | |
2900 | dropped = heap_insert(heap, p); | |
2901 | if (dropped == NULL) { | |
2902 | /* | |
2903 | * The new task was inserted; the heap wasn't | |
2904 | * previously full | |
2905 | */ | |
2906 | get_task_struct(p); | |
2907 | } else if (dropped != p) { | |
2908 | /* | |
2909 | * The new task was inserted, and pushed out a | |
2910 | * different task | |
2911 | */ | |
2912 | get_task_struct(p); | |
2913 | put_task_struct(dropped); | |
2914 | } | |
2915 | /* | |
2916 | * Else the new task was newer than anything already in | |
2917 | * the heap and wasn't inserted | |
2918 | */ | |
2919 | } | |
2920 | cgroup_iter_end(scan->cg, &it); | |
2921 | ||
2922 | if (heap->size) { | |
2923 | for (i = 0; i < heap->size; i++) { | |
4fe91d51 | 2924 | struct task_struct *q = heap->ptrs[i]; |
31a7df01 | 2925 | if (i == 0) { |
4fe91d51 PJ |
2926 | latest_time = q->start_time; |
2927 | latest_task = q; | |
31a7df01 CW |
2928 | } |
2929 | /* Process the task per the caller's callback */ | |
4fe91d51 PJ |
2930 | scan->process_task(q, scan); |
2931 | put_task_struct(q); | |
31a7df01 CW |
2932 | } |
2933 | /* | |
2934 | * If we had to process any tasks at all, scan again | |
2935 | * in case some of them were in the middle of forking | |
2936 | * children that didn't get processed. | |
2937 | * Not the most efficient way to do it, but it avoids | |
2938 | * having to take callback_mutex in the fork path | |
2939 | */ | |
2940 | goto again; | |
2941 | } | |
2942 | if (heap == &tmp_heap) | |
2943 | heap_free(&tmp_heap); | |
2944 | return 0; | |
2945 | } | |
2946 | ||
bbcb81d0 | 2947 | /* |
102a775e | 2948 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
2949 | * |
2950 | * Reading this file can return large amounts of data if a cgroup has | |
2951 | * *lots* of attached tasks. So it may need several calls to read(), | |
2952 | * but we cannot guarantee that the information we produce is correct | |
2953 | * unless we produce it entirely atomically. | |
2954 | * | |
bbcb81d0 | 2955 | */ |
bbcb81d0 | 2956 | |
24528255 LZ |
2957 | /* which pidlist file are we talking about? */ |
2958 | enum cgroup_filetype { | |
2959 | CGROUP_FILE_PROCS, | |
2960 | CGROUP_FILE_TASKS, | |
2961 | }; | |
2962 | ||
2963 | /* | |
2964 | * A pidlist is a list of pids that virtually represents the contents of one | |
2965 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
2966 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
2967 | * to the cgroup. | |
2968 | */ | |
2969 | struct cgroup_pidlist { | |
2970 | /* | |
2971 | * used to find which pidlist is wanted. doesn't change as long as | |
2972 | * this particular list stays in the list. | |
2973 | */ | |
2974 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
2975 | /* array of xids */ | |
2976 | pid_t *list; | |
2977 | /* how many elements the above list has */ | |
2978 | int length; | |
2979 | /* how many files are using the current array */ | |
2980 | int use_count; | |
2981 | /* each of these stored in a list by its cgroup */ | |
2982 | struct list_head links; | |
2983 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
2984 | struct cgroup *owner; | |
2985 | /* protects the other fields */ | |
2986 | struct rw_semaphore mutex; | |
2987 | }; | |
2988 | ||
d1d9fd33 BB |
2989 | /* |
2990 | * The following two functions "fix" the issue where there are more pids | |
2991 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
2992 | * TODO: replace with a kernel-wide solution to this problem | |
2993 | */ | |
2994 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
2995 | static void *pidlist_allocate(int count) | |
2996 | { | |
2997 | if (PIDLIST_TOO_LARGE(count)) | |
2998 | return vmalloc(count * sizeof(pid_t)); | |
2999 | else | |
3000 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
3001 | } | |
3002 | static void pidlist_free(void *p) | |
3003 | { | |
3004 | if (is_vmalloc_addr(p)) | |
3005 | vfree(p); | |
3006 | else | |
3007 | kfree(p); | |
3008 | } | |
3009 | static void *pidlist_resize(void *p, int newcount) | |
3010 | { | |
3011 | void *newlist; | |
3012 | /* note: if new alloc fails, old p will still be valid either way */ | |
3013 | if (is_vmalloc_addr(p)) { | |
3014 | newlist = vmalloc(newcount * sizeof(pid_t)); | |
3015 | if (!newlist) | |
3016 | return NULL; | |
3017 | memcpy(newlist, p, newcount * sizeof(pid_t)); | |
3018 | vfree(p); | |
3019 | } else { | |
3020 | newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL); | |
3021 | } | |
3022 | return newlist; | |
3023 | } | |
3024 | ||
bbcb81d0 | 3025 | /* |
102a775e BB |
3026 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
3027 | * If the new stripped list is sufficiently smaller and there's enough memory | |
3028 | * to allocate a new buffer, will let go of the unneeded memory. Returns the | |
3029 | * number of unique elements. | |
bbcb81d0 | 3030 | */ |
102a775e BB |
3031 | /* is the size difference enough that we should re-allocate the array? */ |
3032 | #define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new)) | |
3033 | static int pidlist_uniq(pid_t **p, int length) | |
bbcb81d0 | 3034 | { |
102a775e BB |
3035 | int src, dest = 1; |
3036 | pid_t *list = *p; | |
3037 | pid_t *newlist; | |
3038 | ||
3039 | /* | |
3040 | * we presume the 0th element is unique, so i starts at 1. trivial | |
3041 | * edge cases first; no work needs to be done for either | |
3042 | */ | |
3043 | if (length == 0 || length == 1) | |
3044 | return length; | |
3045 | /* src and dest walk down the list; dest counts unique elements */ | |
3046 | for (src = 1; src < length; src++) { | |
3047 | /* find next unique element */ | |
3048 | while (list[src] == list[src-1]) { | |
3049 | src++; | |
3050 | if (src == length) | |
3051 | goto after; | |
3052 | } | |
3053 | /* dest always points to where the next unique element goes */ | |
3054 | list[dest] = list[src]; | |
3055 | dest++; | |
3056 | } | |
3057 | after: | |
3058 | /* | |
3059 | * if the length difference is large enough, we want to allocate a | |
3060 | * smaller buffer to save memory. if this fails due to out of memory, | |
3061 | * we'll just stay with what we've got. | |
3062 | */ | |
3063 | if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) { | |
d1d9fd33 | 3064 | newlist = pidlist_resize(list, dest); |
102a775e BB |
3065 | if (newlist) |
3066 | *p = newlist; | |
3067 | } | |
3068 | return dest; | |
3069 | } | |
3070 | ||
3071 | static int cmppid(const void *a, const void *b) | |
3072 | { | |
3073 | return *(pid_t *)a - *(pid_t *)b; | |
3074 | } | |
3075 | ||
72a8cb30 BB |
3076 | /* |
3077 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
3078 | * returns with the lock on that pidlist already held, and takes care | |
3079 | * of the use count, or returns NULL with no locks held if we're out of | |
3080 | * memory. | |
3081 | */ | |
3082 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, | |
3083 | enum cgroup_filetype type) | |
3084 | { | |
3085 | struct cgroup_pidlist *l; | |
3086 | /* don't need task_nsproxy() if we're looking at ourself */ | |
b70cc5fd LZ |
3087 | struct pid_namespace *ns = current->nsproxy->pid_ns; |
3088 | ||
72a8cb30 BB |
3089 | /* |
3090 | * We can't drop the pidlist_mutex before taking the l->mutex in case | |
3091 | * the last ref-holder is trying to remove l from the list at the same | |
3092 | * time. Holding the pidlist_mutex precludes somebody taking whichever | |
3093 | * list we find out from under us - compare release_pid_array(). | |
3094 | */ | |
3095 | mutex_lock(&cgrp->pidlist_mutex); | |
3096 | list_for_each_entry(l, &cgrp->pidlists, links) { | |
3097 | if (l->key.type == type && l->key.ns == ns) { | |
72a8cb30 BB |
3098 | /* make sure l doesn't vanish out from under us */ |
3099 | down_write(&l->mutex); | |
3100 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
3101 | return l; |
3102 | } | |
3103 | } | |
3104 | /* entry not found; create a new one */ | |
3105 | l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); | |
3106 | if (!l) { | |
3107 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
3108 | return l; |
3109 | } | |
3110 | init_rwsem(&l->mutex); | |
3111 | down_write(&l->mutex); | |
3112 | l->key.type = type; | |
b70cc5fd | 3113 | l->key.ns = get_pid_ns(ns); |
72a8cb30 BB |
3114 | l->use_count = 0; /* don't increment here */ |
3115 | l->list = NULL; | |
3116 | l->owner = cgrp; | |
3117 | list_add(&l->links, &cgrp->pidlists); | |
3118 | mutex_unlock(&cgrp->pidlist_mutex); | |
3119 | return l; | |
3120 | } | |
3121 | ||
102a775e BB |
3122 | /* |
3123 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
3124 | */ | |
72a8cb30 BB |
3125 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
3126 | struct cgroup_pidlist **lp) | |
102a775e BB |
3127 | { |
3128 | pid_t *array; | |
3129 | int length; | |
3130 | int pid, n = 0; /* used for populating the array */ | |
817929ec PM |
3131 | struct cgroup_iter it; |
3132 | struct task_struct *tsk; | |
102a775e BB |
3133 | struct cgroup_pidlist *l; |
3134 | ||
3135 | /* | |
3136 | * If cgroup gets more users after we read count, we won't have | |
3137 | * enough space - tough. This race is indistinguishable to the | |
3138 | * caller from the case that the additional cgroup users didn't | |
3139 | * show up until sometime later on. | |
3140 | */ | |
3141 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 3142 | array = pidlist_allocate(length); |
102a775e BB |
3143 | if (!array) |
3144 | return -ENOMEM; | |
3145 | /* now, populate the array */ | |
bd89aabc PM |
3146 | cgroup_iter_start(cgrp, &it); |
3147 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
102a775e | 3148 | if (unlikely(n == length)) |
817929ec | 3149 | break; |
102a775e | 3150 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
3151 | if (type == CGROUP_FILE_PROCS) |
3152 | pid = task_tgid_vnr(tsk); | |
3153 | else | |
3154 | pid = task_pid_vnr(tsk); | |
102a775e BB |
3155 | if (pid > 0) /* make sure to only use valid results */ |
3156 | array[n++] = pid; | |
817929ec | 3157 | } |
bd89aabc | 3158 | cgroup_iter_end(cgrp, &it); |
102a775e BB |
3159 | length = n; |
3160 | /* now sort & (if procs) strip out duplicates */ | |
3161 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 3162 | if (type == CGROUP_FILE_PROCS) |
102a775e | 3163 | length = pidlist_uniq(&array, length); |
72a8cb30 BB |
3164 | l = cgroup_pidlist_find(cgrp, type); |
3165 | if (!l) { | |
d1d9fd33 | 3166 | pidlist_free(array); |
72a8cb30 | 3167 | return -ENOMEM; |
102a775e | 3168 | } |
72a8cb30 | 3169 | /* store array, freeing old if necessary - lock already held */ |
d1d9fd33 | 3170 | pidlist_free(l->list); |
102a775e BB |
3171 | l->list = array; |
3172 | l->length = length; | |
3173 | l->use_count++; | |
3174 | up_write(&l->mutex); | |
72a8cb30 | 3175 | *lp = l; |
102a775e | 3176 | return 0; |
bbcb81d0 PM |
3177 | } |
3178 | ||
846c7bb0 | 3179 | /** |
a043e3b2 | 3180 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
3181 | * @stats: cgroupstats to fill information into |
3182 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
3183 | * been requested. | |
a043e3b2 LZ |
3184 | * |
3185 | * Build and fill cgroupstats so that taskstats can export it to user | |
3186 | * space. | |
846c7bb0 BS |
3187 | */ |
3188 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
3189 | { | |
3190 | int ret = -EINVAL; | |
bd89aabc | 3191 | struct cgroup *cgrp; |
846c7bb0 BS |
3192 | struct cgroup_iter it; |
3193 | struct task_struct *tsk; | |
33d283be | 3194 | |
846c7bb0 | 3195 | /* |
33d283be LZ |
3196 | * Validate dentry by checking the superblock operations, |
3197 | * and make sure it's a directory. | |
846c7bb0 | 3198 | */ |
33d283be LZ |
3199 | if (dentry->d_sb->s_op != &cgroup_ops || |
3200 | !S_ISDIR(dentry->d_inode->i_mode)) | |
846c7bb0 BS |
3201 | goto err; |
3202 | ||
3203 | ret = 0; | |
bd89aabc | 3204 | cgrp = dentry->d_fsdata; |
846c7bb0 | 3205 | |
bd89aabc PM |
3206 | cgroup_iter_start(cgrp, &it); |
3207 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
846c7bb0 BS |
3208 | switch (tsk->state) { |
3209 | case TASK_RUNNING: | |
3210 | stats->nr_running++; | |
3211 | break; | |
3212 | case TASK_INTERRUPTIBLE: | |
3213 | stats->nr_sleeping++; | |
3214 | break; | |
3215 | case TASK_UNINTERRUPTIBLE: | |
3216 | stats->nr_uninterruptible++; | |
3217 | break; | |
3218 | case TASK_STOPPED: | |
3219 | stats->nr_stopped++; | |
3220 | break; | |
3221 | default: | |
3222 | if (delayacct_is_task_waiting_on_io(tsk)) | |
3223 | stats->nr_io_wait++; | |
3224 | break; | |
3225 | } | |
3226 | } | |
bd89aabc | 3227 | cgroup_iter_end(cgrp, &it); |
846c7bb0 | 3228 | |
846c7bb0 BS |
3229 | err: |
3230 | return ret; | |
3231 | } | |
3232 | ||
8f3ff208 | 3233 | |
bbcb81d0 | 3234 | /* |
102a775e | 3235 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 3236 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 3237 | * in the cgroup->l->list array. |
bbcb81d0 | 3238 | */ |
cc31edce | 3239 | |
102a775e | 3240 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 3241 | { |
cc31edce PM |
3242 | /* |
3243 | * Initially we receive a position value that corresponds to | |
3244 | * one more than the last pid shown (or 0 on the first call or | |
3245 | * after a seek to the start). Use a binary-search to find the | |
3246 | * next pid to display, if any | |
3247 | */ | |
102a775e | 3248 | struct cgroup_pidlist *l = s->private; |
cc31edce PM |
3249 | int index = 0, pid = *pos; |
3250 | int *iter; | |
3251 | ||
102a775e | 3252 | down_read(&l->mutex); |
cc31edce | 3253 | if (pid) { |
102a775e | 3254 | int end = l->length; |
20777766 | 3255 | |
cc31edce PM |
3256 | while (index < end) { |
3257 | int mid = (index + end) / 2; | |
102a775e | 3258 | if (l->list[mid] == pid) { |
cc31edce PM |
3259 | index = mid; |
3260 | break; | |
102a775e | 3261 | } else if (l->list[mid] <= pid) |
cc31edce PM |
3262 | index = mid + 1; |
3263 | else | |
3264 | end = mid; | |
3265 | } | |
3266 | } | |
3267 | /* If we're off the end of the array, we're done */ | |
102a775e | 3268 | if (index >= l->length) |
cc31edce PM |
3269 | return NULL; |
3270 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 3271 | iter = l->list + index; |
cc31edce PM |
3272 | *pos = *iter; |
3273 | return iter; | |
3274 | } | |
3275 | ||
102a775e | 3276 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 3277 | { |
102a775e BB |
3278 | struct cgroup_pidlist *l = s->private; |
3279 | up_read(&l->mutex); | |
cc31edce PM |
3280 | } |
3281 | ||
102a775e | 3282 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 3283 | { |
102a775e BB |
3284 | struct cgroup_pidlist *l = s->private; |
3285 | pid_t *p = v; | |
3286 | pid_t *end = l->list + l->length; | |
cc31edce PM |
3287 | /* |
3288 | * Advance to the next pid in the array. If this goes off the | |
3289 | * end, we're done | |
3290 | */ | |
3291 | p++; | |
3292 | if (p >= end) { | |
3293 | return NULL; | |
3294 | } else { | |
3295 | *pos = *p; | |
3296 | return p; | |
3297 | } | |
3298 | } | |
3299 | ||
102a775e | 3300 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce PM |
3301 | { |
3302 | return seq_printf(s, "%d\n", *(int *)v); | |
3303 | } | |
bbcb81d0 | 3304 | |
102a775e BB |
3305 | /* |
3306 | * seq_operations functions for iterating on pidlists through seq_file - | |
3307 | * independent of whether it's tasks or procs | |
3308 | */ | |
3309 | static const struct seq_operations cgroup_pidlist_seq_operations = { | |
3310 | .start = cgroup_pidlist_start, | |
3311 | .stop = cgroup_pidlist_stop, | |
3312 | .next = cgroup_pidlist_next, | |
3313 | .show = cgroup_pidlist_show, | |
cc31edce PM |
3314 | }; |
3315 | ||
102a775e | 3316 | static void cgroup_release_pid_array(struct cgroup_pidlist *l) |
cc31edce | 3317 | { |
72a8cb30 BB |
3318 | /* |
3319 | * the case where we're the last user of this particular pidlist will | |
3320 | * have us remove it from the cgroup's list, which entails taking the | |
3321 | * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> | |
3322 | * pidlist_mutex, we have to take pidlist_mutex first. | |
3323 | */ | |
3324 | mutex_lock(&l->owner->pidlist_mutex); | |
102a775e BB |
3325 | down_write(&l->mutex); |
3326 | BUG_ON(!l->use_count); | |
3327 | if (!--l->use_count) { | |
72a8cb30 BB |
3328 | /* we're the last user if refcount is 0; remove and free */ |
3329 | list_del(&l->links); | |
3330 | mutex_unlock(&l->owner->pidlist_mutex); | |
d1d9fd33 | 3331 | pidlist_free(l->list); |
72a8cb30 BB |
3332 | put_pid_ns(l->key.ns); |
3333 | up_write(&l->mutex); | |
3334 | kfree(l); | |
3335 | return; | |
cc31edce | 3336 | } |
72a8cb30 | 3337 | mutex_unlock(&l->owner->pidlist_mutex); |
102a775e | 3338 | up_write(&l->mutex); |
bbcb81d0 PM |
3339 | } |
3340 | ||
102a775e | 3341 | static int cgroup_pidlist_release(struct inode *inode, struct file *file) |
cc31edce | 3342 | { |
102a775e | 3343 | struct cgroup_pidlist *l; |
cc31edce PM |
3344 | if (!(file->f_mode & FMODE_READ)) |
3345 | return 0; | |
102a775e BB |
3346 | /* |
3347 | * the seq_file will only be initialized if the file was opened for | |
3348 | * reading; hence we check if it's not null only in that case. | |
3349 | */ | |
3350 | l = ((struct seq_file *)file->private_data)->private; | |
3351 | cgroup_release_pid_array(l); | |
cc31edce PM |
3352 | return seq_release(inode, file); |
3353 | } | |
3354 | ||
102a775e | 3355 | static const struct file_operations cgroup_pidlist_operations = { |
cc31edce PM |
3356 | .read = seq_read, |
3357 | .llseek = seq_lseek, | |
3358 | .write = cgroup_file_write, | |
102a775e | 3359 | .release = cgroup_pidlist_release, |
cc31edce PM |
3360 | }; |
3361 | ||
bbcb81d0 | 3362 | /* |
102a775e BB |
3363 | * The following functions handle opens on a file that displays a pidlist |
3364 | * (tasks or procs). Prepare an array of the process/thread IDs of whoever's | |
3365 | * in the cgroup. | |
bbcb81d0 | 3366 | */ |
102a775e | 3367 | /* helper function for the two below it */ |
72a8cb30 | 3368 | static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) |
bbcb81d0 | 3369 | { |
bd89aabc | 3370 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
72a8cb30 | 3371 | struct cgroup_pidlist *l; |
cc31edce | 3372 | int retval; |
bbcb81d0 | 3373 | |
cc31edce | 3374 | /* Nothing to do for write-only files */ |
bbcb81d0 PM |
3375 | if (!(file->f_mode & FMODE_READ)) |
3376 | return 0; | |
3377 | ||
102a775e | 3378 | /* have the array populated */ |
72a8cb30 | 3379 | retval = pidlist_array_load(cgrp, type, &l); |
102a775e BB |
3380 | if (retval) |
3381 | return retval; | |
3382 | /* configure file information */ | |
3383 | file->f_op = &cgroup_pidlist_operations; | |
cc31edce | 3384 | |
102a775e | 3385 | retval = seq_open(file, &cgroup_pidlist_seq_operations); |
cc31edce | 3386 | if (retval) { |
102a775e | 3387 | cgroup_release_pid_array(l); |
cc31edce | 3388 | return retval; |
bbcb81d0 | 3389 | } |
102a775e | 3390 | ((struct seq_file *)file->private_data)->private = l; |
bbcb81d0 PM |
3391 | return 0; |
3392 | } | |
102a775e BB |
3393 | static int cgroup_tasks_open(struct inode *unused, struct file *file) |
3394 | { | |
72a8cb30 | 3395 | return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); |
102a775e BB |
3396 | } |
3397 | static int cgroup_procs_open(struct inode *unused, struct file *file) | |
3398 | { | |
72a8cb30 | 3399 | return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); |
102a775e | 3400 | } |
bbcb81d0 | 3401 | |
bd89aabc | 3402 | static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, |
81a6a5cd PM |
3403 | struct cftype *cft) |
3404 | { | |
bd89aabc | 3405 | return notify_on_release(cgrp); |
81a6a5cd PM |
3406 | } |
3407 | ||
6379c106 PM |
3408 | static int cgroup_write_notify_on_release(struct cgroup *cgrp, |
3409 | struct cftype *cft, | |
3410 | u64 val) | |
3411 | { | |
3412 | clear_bit(CGRP_RELEASABLE, &cgrp->flags); | |
3413 | if (val) | |
3414 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3415 | else | |
3416 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3417 | return 0; | |
3418 | } | |
3419 | ||
0dea1168 KS |
3420 | /* |
3421 | * Unregister event and free resources. | |
3422 | * | |
3423 | * Gets called from workqueue. | |
3424 | */ | |
3425 | static void cgroup_event_remove(struct work_struct *work) | |
3426 | { | |
3427 | struct cgroup_event *event = container_of(work, struct cgroup_event, | |
3428 | remove); | |
3429 | struct cgroup *cgrp = event->cgrp; | |
3430 | ||
0dea1168 KS |
3431 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); |
3432 | ||
3433 | eventfd_ctx_put(event->eventfd); | |
0dea1168 | 3434 | kfree(event); |
a0a4db54 | 3435 | dput(cgrp->dentry); |
0dea1168 KS |
3436 | } |
3437 | ||
3438 | /* | |
3439 | * Gets called on POLLHUP on eventfd when user closes it. | |
3440 | * | |
3441 | * Called with wqh->lock held and interrupts disabled. | |
3442 | */ | |
3443 | static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, | |
3444 | int sync, void *key) | |
3445 | { | |
3446 | struct cgroup_event *event = container_of(wait, | |
3447 | struct cgroup_event, wait); | |
3448 | struct cgroup *cgrp = event->cgrp; | |
3449 | unsigned long flags = (unsigned long)key; | |
3450 | ||
3451 | if (flags & POLLHUP) { | |
a93d2f17 | 3452 | __remove_wait_queue(event->wqh, &event->wait); |
0dea1168 KS |
3453 | spin_lock(&cgrp->event_list_lock); |
3454 | list_del(&event->list); | |
3455 | spin_unlock(&cgrp->event_list_lock); | |
3456 | /* | |
3457 | * We are in atomic context, but cgroup_event_remove() may | |
3458 | * sleep, so we have to call it in workqueue. | |
3459 | */ | |
3460 | schedule_work(&event->remove); | |
3461 | } | |
3462 | ||
3463 | return 0; | |
3464 | } | |
3465 | ||
3466 | static void cgroup_event_ptable_queue_proc(struct file *file, | |
3467 | wait_queue_head_t *wqh, poll_table *pt) | |
3468 | { | |
3469 | struct cgroup_event *event = container_of(pt, | |
3470 | struct cgroup_event, pt); | |
3471 | ||
3472 | event->wqh = wqh; | |
3473 | add_wait_queue(wqh, &event->wait); | |
3474 | } | |
3475 | ||
3476 | /* | |
3477 | * Parse input and register new cgroup event handler. | |
3478 | * | |
3479 | * Input must be in format '<event_fd> <control_fd> <args>'. | |
3480 | * Interpretation of args is defined by control file implementation. | |
3481 | */ | |
3482 | static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, | |
3483 | const char *buffer) | |
3484 | { | |
3485 | struct cgroup_event *event = NULL; | |
3486 | unsigned int efd, cfd; | |
3487 | struct file *efile = NULL; | |
3488 | struct file *cfile = NULL; | |
3489 | char *endp; | |
3490 | int ret; | |
3491 | ||
3492 | efd = simple_strtoul(buffer, &endp, 10); | |
3493 | if (*endp != ' ') | |
3494 | return -EINVAL; | |
3495 | buffer = endp + 1; | |
3496 | ||
3497 | cfd = simple_strtoul(buffer, &endp, 10); | |
3498 | if ((*endp != ' ') && (*endp != '\0')) | |
3499 | return -EINVAL; | |
3500 | buffer = endp + 1; | |
3501 | ||
3502 | event = kzalloc(sizeof(*event), GFP_KERNEL); | |
3503 | if (!event) | |
3504 | return -ENOMEM; | |
3505 | event->cgrp = cgrp; | |
3506 | INIT_LIST_HEAD(&event->list); | |
3507 | init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); | |
3508 | init_waitqueue_func_entry(&event->wait, cgroup_event_wake); | |
3509 | INIT_WORK(&event->remove, cgroup_event_remove); | |
3510 | ||
3511 | efile = eventfd_fget(efd); | |
3512 | if (IS_ERR(efile)) { | |
3513 | ret = PTR_ERR(efile); | |
3514 | goto fail; | |
3515 | } | |
3516 | ||
3517 | event->eventfd = eventfd_ctx_fileget(efile); | |
3518 | if (IS_ERR(event->eventfd)) { | |
3519 | ret = PTR_ERR(event->eventfd); | |
3520 | goto fail; | |
3521 | } | |
3522 | ||
3523 | cfile = fget(cfd); | |
3524 | if (!cfile) { | |
3525 | ret = -EBADF; | |
3526 | goto fail; | |
3527 | } | |
3528 | ||
3529 | /* the process need read permission on control file */ | |
3bfa784a AV |
3530 | /* AV: shouldn't we check that it's been opened for read instead? */ |
3531 | ret = inode_permission(cfile->f_path.dentry->d_inode, MAY_READ); | |
0dea1168 KS |
3532 | if (ret < 0) |
3533 | goto fail; | |
3534 | ||
3535 | event->cft = __file_cft(cfile); | |
3536 | if (IS_ERR(event->cft)) { | |
3537 | ret = PTR_ERR(event->cft); | |
3538 | goto fail; | |
3539 | } | |
3540 | ||
3541 | if (!event->cft->register_event || !event->cft->unregister_event) { | |
3542 | ret = -EINVAL; | |
3543 | goto fail; | |
3544 | } | |
3545 | ||
3546 | ret = event->cft->register_event(cgrp, event->cft, | |
3547 | event->eventfd, buffer); | |
3548 | if (ret) | |
3549 | goto fail; | |
3550 | ||
3551 | if (efile->f_op->poll(efile, &event->pt) & POLLHUP) { | |
3552 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); | |
3553 | ret = 0; | |
3554 | goto fail; | |
3555 | } | |
3556 | ||
a0a4db54 KS |
3557 | /* |
3558 | * Events should be removed after rmdir of cgroup directory, but before | |
3559 | * destroying subsystem state objects. Let's take reference to cgroup | |
3560 | * directory dentry to do that. | |
3561 | */ | |
3562 | dget(cgrp->dentry); | |
3563 | ||
0dea1168 KS |
3564 | spin_lock(&cgrp->event_list_lock); |
3565 | list_add(&event->list, &cgrp->event_list); | |
3566 | spin_unlock(&cgrp->event_list_lock); | |
3567 | ||
3568 | fput(cfile); | |
3569 | fput(efile); | |
3570 | ||
3571 | return 0; | |
3572 | ||
3573 | fail: | |
3574 | if (cfile) | |
3575 | fput(cfile); | |
3576 | ||
3577 | if (event && event->eventfd && !IS_ERR(event->eventfd)) | |
3578 | eventfd_ctx_put(event->eventfd); | |
3579 | ||
3580 | if (!IS_ERR_OR_NULL(efile)) | |
3581 | fput(efile); | |
3582 | ||
3583 | kfree(event); | |
3584 | ||
3585 | return ret; | |
3586 | } | |
3587 | ||
97978e6d DL |
3588 | static u64 cgroup_clone_children_read(struct cgroup *cgrp, |
3589 | struct cftype *cft) | |
3590 | { | |
3591 | return clone_children(cgrp); | |
3592 | } | |
3593 | ||
3594 | static int cgroup_clone_children_write(struct cgroup *cgrp, | |
3595 | struct cftype *cft, | |
3596 | u64 val) | |
3597 | { | |
3598 | if (val) | |
3599 | set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3600 | else | |
3601 | clear_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3602 | return 0; | |
3603 | } | |
3604 | ||
bbcb81d0 PM |
3605 | /* |
3606 | * for the common functions, 'private' gives the type of file | |
3607 | */ | |
102a775e BB |
3608 | /* for hysterical raisins, we can't put this on the older files */ |
3609 | #define CGROUP_FILE_GENERIC_PREFIX "cgroup." | |
81a6a5cd PM |
3610 | static struct cftype files[] = { |
3611 | { | |
3612 | .name = "tasks", | |
3613 | .open = cgroup_tasks_open, | |
af351026 | 3614 | .write_u64 = cgroup_tasks_write, |
102a775e | 3615 | .release = cgroup_pidlist_release, |
099fca32 | 3616 | .mode = S_IRUGO | S_IWUSR, |
81a6a5cd | 3617 | }, |
102a775e BB |
3618 | { |
3619 | .name = CGROUP_FILE_GENERIC_PREFIX "procs", | |
3620 | .open = cgroup_procs_open, | |
74a1166d | 3621 | .write_u64 = cgroup_procs_write, |
102a775e | 3622 | .release = cgroup_pidlist_release, |
74a1166d | 3623 | .mode = S_IRUGO | S_IWUSR, |
102a775e | 3624 | }, |
81a6a5cd PM |
3625 | { |
3626 | .name = "notify_on_release", | |
f4c753b7 | 3627 | .read_u64 = cgroup_read_notify_on_release, |
6379c106 | 3628 | .write_u64 = cgroup_write_notify_on_release, |
81a6a5cd | 3629 | }, |
0dea1168 KS |
3630 | { |
3631 | .name = CGROUP_FILE_GENERIC_PREFIX "event_control", | |
3632 | .write_string = cgroup_write_event_control, | |
3633 | .mode = S_IWUGO, | |
3634 | }, | |
97978e6d DL |
3635 | { |
3636 | .name = "cgroup.clone_children", | |
3637 | .read_u64 = cgroup_clone_children_read, | |
3638 | .write_u64 = cgroup_clone_children_write, | |
3639 | }, | |
81a6a5cd PM |
3640 | }; |
3641 | ||
3642 | static struct cftype cft_release_agent = { | |
3643 | .name = "release_agent", | |
e788e066 PM |
3644 | .read_seq_string = cgroup_release_agent_show, |
3645 | .write_string = cgroup_release_agent_write, | |
3646 | .max_write_len = PATH_MAX, | |
bbcb81d0 PM |
3647 | }; |
3648 | ||
bd89aabc | 3649 | static int cgroup_populate_dir(struct cgroup *cgrp) |
ddbcc7e8 PM |
3650 | { |
3651 | int err; | |
3652 | struct cgroup_subsys *ss; | |
3653 | ||
bd89aabc | 3654 | err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files)); |
bbcb81d0 PM |
3655 | if (err < 0) |
3656 | return err; | |
3657 | ||
bd89aabc PM |
3658 | if (cgrp == cgrp->top_cgroup) { |
3659 | if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0) | |
81a6a5cd PM |
3660 | return err; |
3661 | } | |
3662 | ||
bd89aabc PM |
3663 | for_each_subsys(cgrp->root, ss) { |
3664 | if (ss->populate && (err = ss->populate(ss, cgrp)) < 0) | |
ddbcc7e8 PM |
3665 | return err; |
3666 | } | |
38460b48 KH |
3667 | /* This cgroup is ready now */ |
3668 | for_each_subsys(cgrp->root, ss) { | |
3669 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
3670 | /* | |
3671 | * Update id->css pointer and make this css visible from | |
3672 | * CSS ID functions. This pointer will be dereferened | |
3673 | * from RCU-read-side without locks. | |
3674 | */ | |
3675 | if (css->id) | |
3676 | rcu_assign_pointer(css->id->css, css); | |
3677 | } | |
ddbcc7e8 PM |
3678 | |
3679 | return 0; | |
3680 | } | |
3681 | ||
3682 | static void init_cgroup_css(struct cgroup_subsys_state *css, | |
3683 | struct cgroup_subsys *ss, | |
bd89aabc | 3684 | struct cgroup *cgrp) |
ddbcc7e8 | 3685 | { |
bd89aabc | 3686 | css->cgroup = cgrp; |
e7c5ec91 | 3687 | atomic_set(&css->refcnt, 1); |
ddbcc7e8 | 3688 | css->flags = 0; |
38460b48 | 3689 | css->id = NULL; |
bd89aabc | 3690 | if (cgrp == dummytop) |
ddbcc7e8 | 3691 | set_bit(CSS_ROOT, &css->flags); |
bd89aabc PM |
3692 | BUG_ON(cgrp->subsys[ss->subsys_id]); |
3693 | cgrp->subsys[ss->subsys_id] = css; | |
ddbcc7e8 PM |
3694 | } |
3695 | ||
999cd8a4 PM |
3696 | static void cgroup_lock_hierarchy(struct cgroupfs_root *root) |
3697 | { | |
3698 | /* We need to take each hierarchy_mutex in a consistent order */ | |
3699 | int i; | |
3700 | ||
aae8aab4 BB |
3701 | /* |
3702 | * No worry about a race with rebind_subsystems that might mess up the | |
3703 | * locking order, since both parties are under cgroup_mutex. | |
3704 | */ | |
999cd8a4 PM |
3705 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
3706 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
3707 | if (ss == NULL) |
3708 | continue; | |
999cd8a4 | 3709 | if (ss->root == root) |
cfebe563 | 3710 | mutex_lock(&ss->hierarchy_mutex); |
999cd8a4 PM |
3711 | } |
3712 | } | |
3713 | ||
3714 | static void cgroup_unlock_hierarchy(struct cgroupfs_root *root) | |
3715 | { | |
3716 | int i; | |
3717 | ||
3718 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
3719 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
3720 | if (ss == NULL) |
3721 | continue; | |
999cd8a4 PM |
3722 | if (ss->root == root) |
3723 | mutex_unlock(&ss->hierarchy_mutex); | |
3724 | } | |
3725 | } | |
3726 | ||
ddbcc7e8 | 3727 | /* |
a043e3b2 LZ |
3728 | * cgroup_create - create a cgroup |
3729 | * @parent: cgroup that will be parent of the new cgroup | |
3730 | * @dentry: dentry of the new cgroup | |
3731 | * @mode: mode to set on new inode | |
ddbcc7e8 | 3732 | * |
a043e3b2 | 3733 | * Must be called with the mutex on the parent inode held |
ddbcc7e8 | 3734 | */ |
ddbcc7e8 | 3735 | static long cgroup_create(struct cgroup *parent, struct dentry *dentry, |
a5e7ed32 | 3736 | umode_t mode) |
ddbcc7e8 | 3737 | { |
bd89aabc | 3738 | struct cgroup *cgrp; |
ddbcc7e8 PM |
3739 | struct cgroupfs_root *root = parent->root; |
3740 | int err = 0; | |
3741 | struct cgroup_subsys *ss; | |
3742 | struct super_block *sb = root->sb; | |
3743 | ||
bd89aabc PM |
3744 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
3745 | if (!cgrp) | |
ddbcc7e8 PM |
3746 | return -ENOMEM; |
3747 | ||
3748 | /* Grab a reference on the superblock so the hierarchy doesn't | |
3749 | * get deleted on unmount if there are child cgroups. This | |
3750 | * can be done outside cgroup_mutex, since the sb can't | |
3751 | * disappear while someone has an open control file on the | |
3752 | * fs */ | |
3753 | atomic_inc(&sb->s_active); | |
3754 | ||
3755 | mutex_lock(&cgroup_mutex); | |
3756 | ||
cc31edce | 3757 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 3758 | |
bd89aabc PM |
3759 | cgrp->parent = parent; |
3760 | cgrp->root = parent->root; | |
3761 | cgrp->top_cgroup = parent->top_cgroup; | |
ddbcc7e8 | 3762 | |
b6abdb0e LZ |
3763 | if (notify_on_release(parent)) |
3764 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3765 | ||
97978e6d DL |
3766 | if (clone_children(parent)) |
3767 | set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3768 | ||
ddbcc7e8 | 3769 | for_each_subsys(root, ss) { |
761b3ef5 | 3770 | struct cgroup_subsys_state *css = ss->create(cgrp); |
4528fd05 | 3771 | |
ddbcc7e8 PM |
3772 | if (IS_ERR(css)) { |
3773 | err = PTR_ERR(css); | |
3774 | goto err_destroy; | |
3775 | } | |
bd89aabc | 3776 | init_cgroup_css(css, ss, cgrp); |
4528fd05 LZ |
3777 | if (ss->use_id) { |
3778 | err = alloc_css_id(ss, parent, cgrp); | |
3779 | if (err) | |
38460b48 | 3780 | goto err_destroy; |
4528fd05 | 3781 | } |
38460b48 | 3782 | /* At error, ->destroy() callback has to free assigned ID. */ |
97978e6d | 3783 | if (clone_children(parent) && ss->post_clone) |
761b3ef5 | 3784 | ss->post_clone(cgrp); |
ddbcc7e8 PM |
3785 | } |
3786 | ||
999cd8a4 | 3787 | cgroup_lock_hierarchy(root); |
bd89aabc | 3788 | list_add(&cgrp->sibling, &cgrp->parent->children); |
999cd8a4 | 3789 | cgroup_unlock_hierarchy(root); |
ddbcc7e8 PM |
3790 | root->number_of_cgroups++; |
3791 | ||
bd89aabc | 3792 | err = cgroup_create_dir(cgrp, dentry, mode); |
ddbcc7e8 PM |
3793 | if (err < 0) |
3794 | goto err_remove; | |
3795 | ||
3796 | /* The cgroup directory was pre-locked for us */ | |
bd89aabc | 3797 | BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); |
ddbcc7e8 | 3798 | |
b0ca5a84 TH |
3799 | list_add_tail(&cgrp->allcg_node, &root->allcg_list); |
3800 | ||
bd89aabc | 3801 | err = cgroup_populate_dir(cgrp); |
ddbcc7e8 PM |
3802 | /* If err < 0, we have a half-filled directory - oh well ;) */ |
3803 | ||
3804 | mutex_unlock(&cgroup_mutex); | |
bd89aabc | 3805 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
3806 | |
3807 | return 0; | |
3808 | ||
3809 | err_remove: | |
3810 | ||
baef99a0 | 3811 | cgroup_lock_hierarchy(root); |
bd89aabc | 3812 | list_del(&cgrp->sibling); |
baef99a0 | 3813 | cgroup_unlock_hierarchy(root); |
ddbcc7e8 PM |
3814 | root->number_of_cgroups--; |
3815 | ||
3816 | err_destroy: | |
3817 | ||
3818 | for_each_subsys(root, ss) { | |
bd89aabc | 3819 | if (cgrp->subsys[ss->subsys_id]) |
761b3ef5 | 3820 | ss->destroy(cgrp); |
ddbcc7e8 PM |
3821 | } |
3822 | ||
3823 | mutex_unlock(&cgroup_mutex); | |
3824 | ||
3825 | /* Release the reference count that we took on the superblock */ | |
3826 | deactivate_super(sb); | |
3827 | ||
bd89aabc | 3828 | kfree(cgrp); |
ddbcc7e8 PM |
3829 | return err; |
3830 | } | |
3831 | ||
18bb1db3 | 3832 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
ddbcc7e8 PM |
3833 | { |
3834 | struct cgroup *c_parent = dentry->d_parent->d_fsdata; | |
3835 | ||
3836 | /* the vfs holds inode->i_mutex already */ | |
3837 | return cgroup_create(c_parent, dentry, mode | S_IFDIR); | |
3838 | } | |
3839 | ||
55b6fd01 | 3840 | static int cgroup_has_css_refs(struct cgroup *cgrp) |
81a6a5cd PM |
3841 | { |
3842 | /* Check the reference count on each subsystem. Since we | |
3843 | * already established that there are no tasks in the | |
e7c5ec91 | 3844 | * cgroup, if the css refcount is also 1, then there should |
81a6a5cd PM |
3845 | * be no outstanding references, so the subsystem is safe to |
3846 | * destroy. We scan across all subsystems rather than using | |
3847 | * the per-hierarchy linked list of mounted subsystems since | |
3848 | * we can be called via check_for_release() with no | |
3849 | * synchronization other than RCU, and the subsystem linked | |
3850 | * list isn't RCU-safe */ | |
3851 | int i; | |
aae8aab4 BB |
3852 | /* |
3853 | * We won't need to lock the subsys array, because the subsystems | |
3854 | * we're concerned about aren't going anywhere since our cgroup root | |
3855 | * has a reference on them. | |
3856 | */ | |
81a6a5cd PM |
3857 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
3858 | struct cgroup_subsys *ss = subsys[i]; | |
3859 | struct cgroup_subsys_state *css; | |
aae8aab4 BB |
3860 | /* Skip subsystems not present or not in this hierarchy */ |
3861 | if (ss == NULL || ss->root != cgrp->root) | |
81a6a5cd | 3862 | continue; |
bd89aabc | 3863 | css = cgrp->subsys[ss->subsys_id]; |
81a6a5cd PM |
3864 | /* When called from check_for_release() it's possible |
3865 | * that by this point the cgroup has been removed | |
3866 | * and the css deleted. But a false-positive doesn't | |
3867 | * matter, since it can only happen if the cgroup | |
3868 | * has been deleted and hence no longer needs the | |
3869 | * release agent to be called anyway. */ | |
e7c5ec91 | 3870 | if (css && (atomic_read(&css->refcnt) > 1)) |
81a6a5cd | 3871 | return 1; |
81a6a5cd PM |
3872 | } |
3873 | return 0; | |
3874 | } | |
3875 | ||
e7c5ec91 PM |
3876 | /* |
3877 | * Atomically mark all (or else none) of the cgroup's CSS objects as | |
3878 | * CSS_REMOVED. Return true on success, or false if the cgroup has | |
3879 | * busy subsystems. Call with cgroup_mutex held | |
3880 | */ | |
3881 | ||
3882 | static int cgroup_clear_css_refs(struct cgroup *cgrp) | |
3883 | { | |
3884 | struct cgroup_subsys *ss; | |
3885 | unsigned long flags; | |
3886 | bool failed = false; | |
3887 | local_irq_save(flags); | |
3888 | for_each_subsys(cgrp->root, ss) { | |
3889 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
3890 | int refcnt; | |
804b3c28 | 3891 | while (1) { |
e7c5ec91 PM |
3892 | /* We can only remove a CSS with a refcnt==1 */ |
3893 | refcnt = atomic_read(&css->refcnt); | |
3894 | if (refcnt > 1) { | |
3895 | failed = true; | |
3896 | goto done; | |
3897 | } | |
3898 | BUG_ON(!refcnt); | |
3899 | /* | |
3900 | * Drop the refcnt to 0 while we check other | |
3901 | * subsystems. This will cause any racing | |
3902 | * css_tryget() to spin until we set the | |
3903 | * CSS_REMOVED bits or abort | |
3904 | */ | |
804b3c28 PM |
3905 | if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt) |
3906 | break; | |
3907 | cpu_relax(); | |
3908 | } | |
e7c5ec91 PM |
3909 | } |
3910 | done: | |
3911 | for_each_subsys(cgrp->root, ss) { | |
3912 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
3913 | if (failed) { | |
3914 | /* | |
3915 | * Restore old refcnt if we previously managed | |
3916 | * to clear it from 1 to 0 | |
3917 | */ | |
3918 | if (!atomic_read(&css->refcnt)) | |
3919 | atomic_set(&css->refcnt, 1); | |
3920 | } else { | |
3921 | /* Commit the fact that the CSS is removed */ | |
3922 | set_bit(CSS_REMOVED, &css->flags); | |
3923 | } | |
3924 | } | |
3925 | local_irq_restore(flags); | |
3926 | return !failed; | |
3927 | } | |
3928 | ||
ddbcc7e8 PM |
3929 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) |
3930 | { | |
bd89aabc | 3931 | struct cgroup *cgrp = dentry->d_fsdata; |
ddbcc7e8 PM |
3932 | struct dentry *d; |
3933 | struct cgroup *parent; | |
ec64f515 | 3934 | DEFINE_WAIT(wait); |
4ab78683 | 3935 | struct cgroup_event *event, *tmp; |
ec64f515 | 3936 | int ret; |
ddbcc7e8 PM |
3937 | |
3938 | /* the vfs holds both inode->i_mutex already */ | |
ec64f515 | 3939 | again: |
ddbcc7e8 | 3940 | mutex_lock(&cgroup_mutex); |
bd89aabc | 3941 | if (atomic_read(&cgrp->count) != 0) { |
ddbcc7e8 PM |
3942 | mutex_unlock(&cgroup_mutex); |
3943 | return -EBUSY; | |
3944 | } | |
bd89aabc | 3945 | if (!list_empty(&cgrp->children)) { |
ddbcc7e8 PM |
3946 | mutex_unlock(&cgroup_mutex); |
3947 | return -EBUSY; | |
3948 | } | |
3fa59dfb | 3949 | mutex_unlock(&cgroup_mutex); |
a043e3b2 | 3950 | |
88703267 KH |
3951 | /* |
3952 | * In general, subsystem has no css->refcnt after pre_destroy(). But | |
3953 | * in racy cases, subsystem may have to get css->refcnt after | |
3954 | * pre_destroy() and it makes rmdir return with -EBUSY. This sometimes | |
3955 | * make rmdir return -EBUSY too often. To avoid that, we use waitqueue | |
3956 | * for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir | |
3957 | * and subsystem's reference count handling. Please see css_get/put | |
3958 | * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation. | |
3959 | */ | |
3960 | set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
3961 | ||
4fca88c8 | 3962 | /* |
a043e3b2 LZ |
3963 | * Call pre_destroy handlers of subsys. Notify subsystems |
3964 | * that rmdir() request comes. | |
4fca88c8 | 3965 | */ |
ec64f515 | 3966 | ret = cgroup_call_pre_destroy(cgrp); |
88703267 KH |
3967 | if (ret) { |
3968 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
ec64f515 | 3969 | return ret; |
88703267 | 3970 | } |
ddbcc7e8 | 3971 | |
3fa59dfb KH |
3972 | mutex_lock(&cgroup_mutex); |
3973 | parent = cgrp->parent; | |
ec64f515 | 3974 | if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) { |
88703267 | 3975 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); |
ddbcc7e8 PM |
3976 | mutex_unlock(&cgroup_mutex); |
3977 | return -EBUSY; | |
3978 | } | |
ec64f515 | 3979 | prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE); |
ec64f515 KH |
3980 | if (!cgroup_clear_css_refs(cgrp)) { |
3981 | mutex_unlock(&cgroup_mutex); | |
88703267 KH |
3982 | /* |
3983 | * Because someone may call cgroup_wakeup_rmdir_waiter() before | |
3984 | * prepare_to_wait(), we need to check this flag. | |
3985 | */ | |
3986 | if (test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)) | |
3987 | schedule(); | |
ec64f515 KH |
3988 | finish_wait(&cgroup_rmdir_waitq, &wait); |
3989 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
3990 | if (signal_pending(current)) | |
3991 | return -EINTR; | |
3992 | goto again; | |
3993 | } | |
3994 | /* NO css_tryget() can success after here. */ | |
3995 | finish_wait(&cgroup_rmdir_waitq, &wait); | |
3996 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
ddbcc7e8 | 3997 | |
cdcc136f | 3998 | raw_spin_lock(&release_list_lock); |
bd89aabc PM |
3999 | set_bit(CGRP_REMOVED, &cgrp->flags); |
4000 | if (!list_empty(&cgrp->release_list)) | |
8d258797 | 4001 | list_del_init(&cgrp->release_list); |
cdcc136f | 4002 | raw_spin_unlock(&release_list_lock); |
999cd8a4 PM |
4003 | |
4004 | cgroup_lock_hierarchy(cgrp->root); | |
4005 | /* delete this cgroup from parent->children */ | |
8d258797 | 4006 | list_del_init(&cgrp->sibling); |
999cd8a4 PM |
4007 | cgroup_unlock_hierarchy(cgrp->root); |
4008 | ||
b0ca5a84 TH |
4009 | list_del_init(&cgrp->allcg_node); |
4010 | ||
bd89aabc | 4011 | d = dget(cgrp->dentry); |
ddbcc7e8 PM |
4012 | |
4013 | cgroup_d_remove_dir(d); | |
4014 | dput(d); | |
ddbcc7e8 | 4015 | |
bd89aabc | 4016 | set_bit(CGRP_RELEASABLE, &parent->flags); |
81a6a5cd PM |
4017 | check_for_release(parent); |
4018 | ||
4ab78683 KS |
4019 | /* |
4020 | * Unregister events and notify userspace. | |
4021 | * Notify userspace about cgroup removing only after rmdir of cgroup | |
4022 | * directory to avoid race between userspace and kernelspace | |
4023 | */ | |
4024 | spin_lock(&cgrp->event_list_lock); | |
4025 | list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { | |
4026 | list_del(&event->list); | |
4027 | remove_wait_queue(event->wqh, &event->wait); | |
4028 | eventfd_signal(event->eventfd, 1); | |
4029 | schedule_work(&event->remove); | |
4030 | } | |
4031 | spin_unlock(&cgrp->event_list_lock); | |
4032 | ||
ddbcc7e8 | 4033 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
4034 | return 0; |
4035 | } | |
4036 | ||
06a11920 | 4037 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
ddbcc7e8 | 4038 | { |
ddbcc7e8 | 4039 | struct cgroup_subsys_state *css; |
cfe36bde DC |
4040 | |
4041 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 PM |
4042 | |
4043 | /* Create the top cgroup state for this subsystem */ | |
33a68ac1 | 4044 | list_add(&ss->sibling, &rootnode.subsys_list); |
ddbcc7e8 | 4045 | ss->root = &rootnode; |
761b3ef5 | 4046 | css = ss->create(dummytop); |
ddbcc7e8 PM |
4047 | /* We don't handle early failures gracefully */ |
4048 | BUG_ON(IS_ERR(css)); | |
4049 | init_cgroup_css(css, ss, dummytop); | |
4050 | ||
e8d55fde | 4051 | /* Update the init_css_set to contain a subsys |
817929ec | 4052 | * pointer to this state - since the subsystem is |
e8d55fde LZ |
4053 | * newly registered, all tasks and hence the |
4054 | * init_css_set is in the subsystem's top cgroup. */ | |
4055 | init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id]; | |
ddbcc7e8 PM |
4056 | |
4057 | need_forkexit_callback |= ss->fork || ss->exit; | |
4058 | ||
e8d55fde LZ |
4059 | /* At system boot, before all subsystems have been |
4060 | * registered, no tasks have been forked, so we don't | |
4061 | * need to invoke fork callbacks here. */ | |
4062 | BUG_ON(!list_empty(&init_task.tasks)); | |
4063 | ||
999cd8a4 | 4064 | mutex_init(&ss->hierarchy_mutex); |
cfebe563 | 4065 | lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); |
ddbcc7e8 | 4066 | ss->active = 1; |
e6a1105b BB |
4067 | |
4068 | /* this function shouldn't be used with modular subsystems, since they | |
4069 | * need to register a subsys_id, among other things */ | |
4070 | BUG_ON(ss->module); | |
4071 | } | |
4072 | ||
4073 | /** | |
4074 | * cgroup_load_subsys: load and register a modular subsystem at runtime | |
4075 | * @ss: the subsystem to load | |
4076 | * | |
4077 | * This function should be called in a modular subsystem's initcall. If the | |
88393161 | 4078 | * subsystem is built as a module, it will be assigned a new subsys_id and set |
e6a1105b BB |
4079 | * up for use. If the subsystem is built-in anyway, work is delegated to the |
4080 | * simpler cgroup_init_subsys. | |
4081 | */ | |
4082 | int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) | |
4083 | { | |
4084 | int i; | |
4085 | struct cgroup_subsys_state *css; | |
4086 | ||
4087 | /* check name and function validity */ | |
4088 | if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || | |
4089 | ss->create == NULL || ss->destroy == NULL) | |
4090 | return -EINVAL; | |
4091 | ||
4092 | /* | |
4093 | * we don't support callbacks in modular subsystems. this check is | |
4094 | * before the ss->module check for consistency; a subsystem that could | |
4095 | * be a module should still have no callbacks even if the user isn't | |
4096 | * compiling it as one. | |
4097 | */ | |
4098 | if (ss->fork || ss->exit) | |
4099 | return -EINVAL; | |
4100 | ||
4101 | /* | |
4102 | * an optionally modular subsystem is built-in: we want to do nothing, | |
4103 | * since cgroup_init_subsys will have already taken care of it. | |
4104 | */ | |
4105 | if (ss->module == NULL) { | |
4106 | /* a few sanity checks */ | |
4107 | BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT); | |
4108 | BUG_ON(subsys[ss->subsys_id] != ss); | |
4109 | return 0; | |
4110 | } | |
4111 | ||
4112 | /* | |
4113 | * need to register a subsys id before anything else - for example, | |
4114 | * init_cgroup_css needs it. | |
4115 | */ | |
4116 | mutex_lock(&cgroup_mutex); | |
4117 | /* find the first empty slot in the array */ | |
4118 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { | |
4119 | if (subsys[i] == NULL) | |
4120 | break; | |
4121 | } | |
4122 | if (i == CGROUP_SUBSYS_COUNT) { | |
4123 | /* maximum number of subsystems already registered! */ | |
4124 | mutex_unlock(&cgroup_mutex); | |
4125 | return -EBUSY; | |
4126 | } | |
4127 | /* assign ourselves the subsys_id */ | |
4128 | ss->subsys_id = i; | |
4129 | subsys[i] = ss; | |
4130 | ||
4131 | /* | |
4132 | * no ss->create seems to need anything important in the ss struct, so | |
4133 | * this can happen first (i.e. before the rootnode attachment). | |
4134 | */ | |
761b3ef5 | 4135 | css = ss->create(dummytop); |
e6a1105b BB |
4136 | if (IS_ERR(css)) { |
4137 | /* failure case - need to deassign the subsys[] slot. */ | |
4138 | subsys[i] = NULL; | |
4139 | mutex_unlock(&cgroup_mutex); | |
4140 | return PTR_ERR(css); | |
4141 | } | |
4142 | ||
4143 | list_add(&ss->sibling, &rootnode.subsys_list); | |
4144 | ss->root = &rootnode; | |
4145 | ||
4146 | /* our new subsystem will be attached to the dummy hierarchy. */ | |
4147 | init_cgroup_css(css, ss, dummytop); | |
4148 | /* init_idr must be after init_cgroup_css because it sets css->id. */ | |
4149 | if (ss->use_id) { | |
4150 | int ret = cgroup_init_idr(ss, css); | |
4151 | if (ret) { | |
4152 | dummytop->subsys[ss->subsys_id] = NULL; | |
761b3ef5 | 4153 | ss->destroy(dummytop); |
e6a1105b BB |
4154 | subsys[i] = NULL; |
4155 | mutex_unlock(&cgroup_mutex); | |
4156 | return ret; | |
4157 | } | |
4158 | } | |
4159 | ||
4160 | /* | |
4161 | * Now we need to entangle the css into the existing css_sets. unlike | |
4162 | * in cgroup_init_subsys, there are now multiple css_sets, so each one | |
4163 | * will need a new pointer to it; done by iterating the css_set_table. | |
4164 | * furthermore, modifying the existing css_sets will corrupt the hash | |
4165 | * table state, so each changed css_set will need its hash recomputed. | |
4166 | * this is all done under the css_set_lock. | |
4167 | */ | |
4168 | write_lock(&css_set_lock); | |
4169 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { | |
4170 | struct css_set *cg; | |
4171 | struct hlist_node *node, *tmp; | |
4172 | struct hlist_head *bucket = &css_set_table[i], *new_bucket; | |
4173 | ||
4174 | hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) { | |
4175 | /* skip entries that we already rehashed */ | |
4176 | if (cg->subsys[ss->subsys_id]) | |
4177 | continue; | |
4178 | /* remove existing entry */ | |
4179 | hlist_del(&cg->hlist); | |
4180 | /* set new value */ | |
4181 | cg->subsys[ss->subsys_id] = css; | |
4182 | /* recompute hash and restore entry */ | |
4183 | new_bucket = css_set_hash(cg->subsys); | |
4184 | hlist_add_head(&cg->hlist, new_bucket); | |
4185 | } | |
4186 | } | |
4187 | write_unlock(&css_set_lock); | |
4188 | ||
4189 | mutex_init(&ss->hierarchy_mutex); | |
4190 | lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); | |
4191 | ss->active = 1; | |
4192 | ||
e6a1105b BB |
4193 | /* success! */ |
4194 | mutex_unlock(&cgroup_mutex); | |
4195 | return 0; | |
ddbcc7e8 | 4196 | } |
e6a1105b | 4197 | EXPORT_SYMBOL_GPL(cgroup_load_subsys); |
ddbcc7e8 | 4198 | |
cf5d5941 BB |
4199 | /** |
4200 | * cgroup_unload_subsys: unload a modular subsystem | |
4201 | * @ss: the subsystem to unload | |
4202 | * | |
4203 | * This function should be called in a modular subsystem's exitcall. When this | |
4204 | * function is invoked, the refcount on the subsystem's module will be 0, so | |
4205 | * the subsystem will not be attached to any hierarchy. | |
4206 | */ | |
4207 | void cgroup_unload_subsys(struct cgroup_subsys *ss) | |
4208 | { | |
4209 | struct cg_cgroup_link *link; | |
4210 | struct hlist_head *hhead; | |
4211 | ||
4212 | BUG_ON(ss->module == NULL); | |
4213 | ||
4214 | /* | |
4215 | * we shouldn't be called if the subsystem is in use, and the use of | |
4216 | * try_module_get in parse_cgroupfs_options should ensure that it | |
4217 | * doesn't start being used while we're killing it off. | |
4218 | */ | |
4219 | BUG_ON(ss->root != &rootnode); | |
4220 | ||
4221 | mutex_lock(&cgroup_mutex); | |
4222 | /* deassign the subsys_id */ | |
4223 | BUG_ON(ss->subsys_id < CGROUP_BUILTIN_SUBSYS_COUNT); | |
4224 | subsys[ss->subsys_id] = NULL; | |
4225 | ||
4226 | /* remove subsystem from rootnode's list of subsystems */ | |
8d258797 | 4227 | list_del_init(&ss->sibling); |
cf5d5941 BB |
4228 | |
4229 | /* | |
4230 | * disentangle the css from all css_sets attached to the dummytop. as | |
4231 | * in loading, we need to pay our respects to the hashtable gods. | |
4232 | */ | |
4233 | write_lock(&css_set_lock); | |
4234 | list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) { | |
4235 | struct css_set *cg = link->cg; | |
4236 | ||
4237 | hlist_del(&cg->hlist); | |
4238 | BUG_ON(!cg->subsys[ss->subsys_id]); | |
4239 | cg->subsys[ss->subsys_id] = NULL; | |
4240 | hhead = css_set_hash(cg->subsys); | |
4241 | hlist_add_head(&cg->hlist, hhead); | |
4242 | } | |
4243 | write_unlock(&css_set_lock); | |
4244 | ||
4245 | /* | |
4246 | * remove subsystem's css from the dummytop and free it - need to free | |
4247 | * before marking as null because ss->destroy needs the cgrp->subsys | |
4248 | * pointer to find their state. note that this also takes care of | |
4249 | * freeing the css_id. | |
4250 | */ | |
761b3ef5 | 4251 | ss->destroy(dummytop); |
cf5d5941 BB |
4252 | dummytop->subsys[ss->subsys_id] = NULL; |
4253 | ||
4254 | mutex_unlock(&cgroup_mutex); | |
4255 | } | |
4256 | EXPORT_SYMBOL_GPL(cgroup_unload_subsys); | |
4257 | ||
ddbcc7e8 | 4258 | /** |
a043e3b2 LZ |
4259 | * cgroup_init_early - cgroup initialization at system boot |
4260 | * | |
4261 | * Initialize cgroups at system boot, and initialize any | |
4262 | * subsystems that request early init. | |
ddbcc7e8 PM |
4263 | */ |
4264 | int __init cgroup_init_early(void) | |
4265 | { | |
4266 | int i; | |
146aa1bd | 4267 | atomic_set(&init_css_set.refcount, 1); |
817929ec PM |
4268 | INIT_LIST_HEAD(&init_css_set.cg_links); |
4269 | INIT_LIST_HEAD(&init_css_set.tasks); | |
472b1053 | 4270 | INIT_HLIST_NODE(&init_css_set.hlist); |
817929ec | 4271 | css_set_count = 1; |
ddbcc7e8 | 4272 | init_cgroup_root(&rootnode); |
817929ec PM |
4273 | root_count = 1; |
4274 | init_task.cgroups = &init_css_set; | |
4275 | ||
4276 | init_css_set_link.cg = &init_css_set; | |
7717f7ba | 4277 | init_css_set_link.cgrp = dummytop; |
bd89aabc | 4278 | list_add(&init_css_set_link.cgrp_link_list, |
817929ec PM |
4279 | &rootnode.top_cgroup.css_sets); |
4280 | list_add(&init_css_set_link.cg_link_list, | |
4281 | &init_css_set.cg_links); | |
ddbcc7e8 | 4282 | |
472b1053 LZ |
4283 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) |
4284 | INIT_HLIST_HEAD(&css_set_table[i]); | |
4285 | ||
aae8aab4 BB |
4286 | /* at bootup time, we don't worry about modular subsystems */ |
4287 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
ddbcc7e8 PM |
4288 | struct cgroup_subsys *ss = subsys[i]; |
4289 | ||
4290 | BUG_ON(!ss->name); | |
4291 | BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); | |
4292 | BUG_ON(!ss->create); | |
4293 | BUG_ON(!ss->destroy); | |
4294 | if (ss->subsys_id != i) { | |
cfe36bde | 4295 | printk(KERN_ERR "cgroup: Subsys %s id == %d\n", |
ddbcc7e8 PM |
4296 | ss->name, ss->subsys_id); |
4297 | BUG(); | |
4298 | } | |
4299 | ||
4300 | if (ss->early_init) | |
4301 | cgroup_init_subsys(ss); | |
4302 | } | |
4303 | return 0; | |
4304 | } | |
4305 | ||
4306 | /** | |
a043e3b2 LZ |
4307 | * cgroup_init - cgroup initialization |
4308 | * | |
4309 | * Register cgroup filesystem and /proc file, and initialize | |
4310 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
4311 | */ |
4312 | int __init cgroup_init(void) | |
4313 | { | |
4314 | int err; | |
4315 | int i; | |
472b1053 | 4316 | struct hlist_head *hhead; |
a424316c PM |
4317 | |
4318 | err = bdi_init(&cgroup_backing_dev_info); | |
4319 | if (err) | |
4320 | return err; | |
ddbcc7e8 | 4321 | |
aae8aab4 BB |
4322 | /* at bootup time, we don't worry about modular subsystems */ |
4323 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
ddbcc7e8 PM |
4324 | struct cgroup_subsys *ss = subsys[i]; |
4325 | if (!ss->early_init) | |
4326 | cgroup_init_subsys(ss); | |
38460b48 | 4327 | if (ss->use_id) |
e6a1105b | 4328 | cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]); |
ddbcc7e8 PM |
4329 | } |
4330 | ||
472b1053 LZ |
4331 | /* Add init_css_set to the hash table */ |
4332 | hhead = css_set_hash(init_css_set.subsys); | |
4333 | hlist_add_head(&init_css_set.hlist, hhead); | |
2c6ab6d2 | 4334 | BUG_ON(!init_root_id(&rootnode)); |
676db4af GKH |
4335 | |
4336 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); | |
4337 | if (!cgroup_kobj) { | |
4338 | err = -ENOMEM; | |
4339 | goto out; | |
4340 | } | |
4341 | ||
ddbcc7e8 | 4342 | err = register_filesystem(&cgroup_fs_type); |
676db4af GKH |
4343 | if (err < 0) { |
4344 | kobject_put(cgroup_kobj); | |
ddbcc7e8 | 4345 | goto out; |
676db4af | 4346 | } |
ddbcc7e8 | 4347 | |
46ae220b | 4348 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
a424316c | 4349 | |
ddbcc7e8 | 4350 | out: |
a424316c PM |
4351 | if (err) |
4352 | bdi_destroy(&cgroup_backing_dev_info); | |
4353 | ||
ddbcc7e8 PM |
4354 | return err; |
4355 | } | |
b4f48b63 | 4356 | |
a424316c PM |
4357 | /* |
4358 | * proc_cgroup_show() | |
4359 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
4360 | * - Used for /proc/<pid>/cgroup. | |
4361 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it | |
4362 | * doesn't really matter if tsk->cgroup changes after we read it, | |
956db3ca | 4363 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it |
a424316c PM |
4364 | * anyway. No need to check that tsk->cgroup != NULL, thanks to |
4365 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks | |
4366 | * cgroup to top_cgroup. | |
4367 | */ | |
4368 | ||
4369 | /* TODO: Use a proper seq_file iterator */ | |
4370 | static int proc_cgroup_show(struct seq_file *m, void *v) | |
4371 | { | |
4372 | struct pid *pid; | |
4373 | struct task_struct *tsk; | |
4374 | char *buf; | |
4375 | int retval; | |
4376 | struct cgroupfs_root *root; | |
4377 | ||
4378 | retval = -ENOMEM; | |
4379 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
4380 | if (!buf) | |
4381 | goto out; | |
4382 | ||
4383 | retval = -ESRCH; | |
4384 | pid = m->private; | |
4385 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
4386 | if (!tsk) | |
4387 | goto out_free; | |
4388 | ||
4389 | retval = 0; | |
4390 | ||
4391 | mutex_lock(&cgroup_mutex); | |
4392 | ||
e5f6a860 | 4393 | for_each_active_root(root) { |
a424316c | 4394 | struct cgroup_subsys *ss; |
bd89aabc | 4395 | struct cgroup *cgrp; |
a424316c PM |
4396 | int count = 0; |
4397 | ||
2c6ab6d2 | 4398 | seq_printf(m, "%d:", root->hierarchy_id); |
a424316c PM |
4399 | for_each_subsys(root, ss) |
4400 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); | |
c6d57f33 PM |
4401 | if (strlen(root->name)) |
4402 | seq_printf(m, "%sname=%s", count ? "," : "", | |
4403 | root->name); | |
a424316c | 4404 | seq_putc(m, ':'); |
7717f7ba | 4405 | cgrp = task_cgroup_from_root(tsk, root); |
bd89aabc | 4406 | retval = cgroup_path(cgrp, buf, PAGE_SIZE); |
a424316c PM |
4407 | if (retval < 0) |
4408 | goto out_unlock; | |
4409 | seq_puts(m, buf); | |
4410 | seq_putc(m, '\n'); | |
4411 | } | |
4412 | ||
4413 | out_unlock: | |
4414 | mutex_unlock(&cgroup_mutex); | |
4415 | put_task_struct(tsk); | |
4416 | out_free: | |
4417 | kfree(buf); | |
4418 | out: | |
4419 | return retval; | |
4420 | } | |
4421 | ||
4422 | static int cgroup_open(struct inode *inode, struct file *file) | |
4423 | { | |
4424 | struct pid *pid = PROC_I(inode)->pid; | |
4425 | return single_open(file, proc_cgroup_show, pid); | |
4426 | } | |
4427 | ||
828c0950 | 4428 | const struct file_operations proc_cgroup_operations = { |
a424316c PM |
4429 | .open = cgroup_open, |
4430 | .read = seq_read, | |
4431 | .llseek = seq_lseek, | |
4432 | .release = single_release, | |
4433 | }; | |
4434 | ||
4435 | /* Display information about each subsystem and each hierarchy */ | |
4436 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
4437 | { | |
4438 | int i; | |
a424316c | 4439 | |
8bab8dde | 4440 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
4441 | /* |
4442 | * ideally we don't want subsystems moving around while we do this. | |
4443 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
4444 | * subsys/hierarchy state. | |
4445 | */ | |
a424316c | 4446 | mutex_lock(&cgroup_mutex); |
a424316c PM |
4447 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
4448 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
4449 | if (ss == NULL) |
4450 | continue; | |
2c6ab6d2 PM |
4451 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
4452 | ss->name, ss->root->hierarchy_id, | |
8bab8dde | 4453 | ss->root->number_of_cgroups, !ss->disabled); |
a424316c PM |
4454 | } |
4455 | mutex_unlock(&cgroup_mutex); | |
4456 | return 0; | |
4457 | } | |
4458 | ||
4459 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
4460 | { | |
9dce07f1 | 4461 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
4462 | } |
4463 | ||
828c0950 | 4464 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
4465 | .open = cgroupstats_open, |
4466 | .read = seq_read, | |
4467 | .llseek = seq_lseek, | |
4468 | .release = single_release, | |
4469 | }; | |
4470 | ||
b4f48b63 PM |
4471 | /** |
4472 | * cgroup_fork - attach newly forked task to its parents cgroup. | |
a043e3b2 | 4473 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 PM |
4474 | * |
4475 | * Description: A task inherits its parent's cgroup at fork(). | |
4476 | * | |
4477 | * A pointer to the shared css_set was automatically copied in | |
4478 | * fork.c by dup_task_struct(). However, we ignore that copy, since | |
7e381b0e FW |
4479 | * it was not made under the protection of RCU, cgroup_mutex or |
4480 | * threadgroup_change_begin(), so it might no longer be a valid | |
4481 | * cgroup pointer. cgroup_attach_task() might have already changed | |
4482 | * current->cgroups, allowing the previously referenced cgroup | |
4483 | * group to be removed and freed. | |
4484 | * | |
4485 | * Outside the pointer validity we also need to process the css_set | |
4486 | * inheritance between threadgoup_change_begin() and | |
4487 | * threadgoup_change_end(), this way there is no leak in any process | |
4488 | * wide migration performed by cgroup_attach_proc() that could otherwise | |
4489 | * miss a thread because it is too early or too late in the fork stage. | |
b4f48b63 PM |
4490 | * |
4491 | * At the point that cgroup_fork() is called, 'current' is the parent | |
4492 | * task, and the passed argument 'child' points to the child task. | |
4493 | */ | |
4494 | void cgroup_fork(struct task_struct *child) | |
4495 | { | |
7e381b0e FW |
4496 | /* |
4497 | * We don't need to task_lock() current because current->cgroups | |
4498 | * can't be changed concurrently here. The parent obviously hasn't | |
4499 | * exited and called cgroup_exit(), and we are synchronized against | |
4500 | * cgroup migration through threadgroup_change_begin(). | |
4501 | */ | |
817929ec PM |
4502 | child->cgroups = current->cgroups; |
4503 | get_css_set(child->cgroups); | |
817929ec | 4504 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
4505 | } |
4506 | ||
4507 | /** | |
a043e3b2 LZ |
4508 | * cgroup_fork_callbacks - run fork callbacks |
4509 | * @child: the new task | |
4510 | * | |
4511 | * Called on a new task very soon before adding it to the | |
4512 | * tasklist. No need to take any locks since no-one can | |
4513 | * be operating on this task. | |
b4f48b63 PM |
4514 | */ |
4515 | void cgroup_fork_callbacks(struct task_struct *child) | |
4516 | { | |
4517 | if (need_forkexit_callback) { | |
4518 | int i; | |
aae8aab4 BB |
4519 | /* |
4520 | * forkexit callbacks are only supported for builtin | |
4521 | * subsystems, and the builtin section of the subsys array is | |
4522 | * immutable, so we don't need to lock the subsys array here. | |
4523 | */ | |
4524 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
b4f48b63 PM |
4525 | struct cgroup_subsys *ss = subsys[i]; |
4526 | if (ss->fork) | |
761b3ef5 | 4527 | ss->fork(child); |
b4f48b63 PM |
4528 | } |
4529 | } | |
4530 | } | |
4531 | ||
817929ec | 4532 | /** |
a043e3b2 LZ |
4533 | * cgroup_post_fork - called on a new task after adding it to the task list |
4534 | * @child: the task in question | |
4535 | * | |
4536 | * Adds the task to the list running through its css_set if necessary. | |
4537 | * Has to be after the task is visible on the task list in case we race | |
4538 | * with the first call to cgroup_iter_start() - to guarantee that the | |
4539 | * new task ends up on its list. | |
4540 | */ | |
817929ec PM |
4541 | void cgroup_post_fork(struct task_struct *child) |
4542 | { | |
3ce3230a FW |
4543 | /* |
4544 | * use_task_css_set_links is set to 1 before we walk the tasklist | |
4545 | * under the tasklist_lock and we read it here after we added the child | |
4546 | * to the tasklist under the tasklist_lock as well. If the child wasn't | |
4547 | * yet in the tasklist when we walked through it from | |
4548 | * cgroup_enable_task_cg_lists(), then use_task_css_set_links value | |
4549 | * should be visible now due to the paired locking and barriers implied | |
4550 | * by LOCK/UNLOCK: it is written before the tasklist_lock unlock | |
4551 | * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock | |
4552 | * lock on fork. | |
4553 | */ | |
817929ec PM |
4554 | if (use_task_css_set_links) { |
4555 | write_lock(&css_set_lock); | |
7e3aa30a FW |
4556 | if (list_empty(&child->cg_list)) { |
4557 | /* | |
4558 | * It's safe to use child->cgroups without task_lock() | |
4559 | * here because we are protected through | |
4560 | * threadgroup_change_begin() against concurrent | |
4561 | * css_set change in cgroup_task_migrate(). Also | |
4562 | * the task can't exit at that point until | |
4563 | * wake_up_new_task() is called, so we are protected | |
4564 | * against cgroup_exit() setting child->cgroup to | |
4565 | * init_css_set. | |
4566 | */ | |
817929ec | 4567 | list_add(&child->cg_list, &child->cgroups->tasks); |
7e3aa30a | 4568 | } |
817929ec PM |
4569 | write_unlock(&css_set_lock); |
4570 | } | |
4571 | } | |
b4f48b63 PM |
4572 | /** |
4573 | * cgroup_exit - detach cgroup from exiting task | |
4574 | * @tsk: pointer to task_struct of exiting process | |
a043e3b2 | 4575 | * @run_callback: run exit callbacks? |
b4f48b63 PM |
4576 | * |
4577 | * Description: Detach cgroup from @tsk and release it. | |
4578 | * | |
4579 | * Note that cgroups marked notify_on_release force every task in | |
4580 | * them to take the global cgroup_mutex mutex when exiting. | |
4581 | * This could impact scaling on very large systems. Be reluctant to | |
4582 | * use notify_on_release cgroups where very high task exit scaling | |
4583 | * is required on large systems. | |
4584 | * | |
4585 | * the_top_cgroup_hack: | |
4586 | * | |
4587 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup). | |
4588 | * | |
4589 | * We call cgroup_exit() while the task is still competent to | |
4590 | * handle notify_on_release(), then leave the task attached to the | |
4591 | * root cgroup in each hierarchy for the remainder of its exit. | |
4592 | * | |
4593 | * To do this properly, we would increment the reference count on | |
4594 | * top_cgroup, and near the very end of the kernel/exit.c do_exit() | |
4595 | * code we would add a second cgroup function call, to drop that | |
4596 | * reference. This would just create an unnecessary hot spot on | |
4597 | * the top_cgroup reference count, to no avail. | |
4598 | * | |
4599 | * Normally, holding a reference to a cgroup without bumping its | |
4600 | * count is unsafe. The cgroup could go away, or someone could | |
4601 | * attach us to a different cgroup, decrementing the count on | |
4602 | * the first cgroup that we never incremented. But in this case, | |
4603 | * top_cgroup isn't going away, and either task has PF_EXITING set, | |
956db3ca CW |
4604 | * which wards off any cgroup_attach_task() attempts, or task is a failed |
4605 | * fork, never visible to cgroup_attach_task. | |
b4f48b63 PM |
4606 | */ |
4607 | void cgroup_exit(struct task_struct *tsk, int run_callbacks) | |
4608 | { | |
817929ec | 4609 | struct css_set *cg; |
d41d5a01 | 4610 | int i; |
817929ec PM |
4611 | |
4612 | /* | |
4613 | * Unlink from the css_set task list if necessary. | |
4614 | * Optimistically check cg_list before taking | |
4615 | * css_set_lock | |
4616 | */ | |
4617 | if (!list_empty(&tsk->cg_list)) { | |
4618 | write_lock(&css_set_lock); | |
4619 | if (!list_empty(&tsk->cg_list)) | |
8d258797 | 4620 | list_del_init(&tsk->cg_list); |
817929ec PM |
4621 | write_unlock(&css_set_lock); |
4622 | } | |
4623 | ||
b4f48b63 PM |
4624 | /* Reassign the task to the init_css_set. */ |
4625 | task_lock(tsk); | |
817929ec PM |
4626 | cg = tsk->cgroups; |
4627 | tsk->cgroups = &init_css_set; | |
d41d5a01 PZ |
4628 | |
4629 | if (run_callbacks && need_forkexit_callback) { | |
4630 | /* | |
4631 | * modular subsystems can't use callbacks, so no need to lock | |
4632 | * the subsys array | |
4633 | */ | |
4634 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
4635 | struct cgroup_subsys *ss = subsys[i]; | |
4636 | if (ss->exit) { | |
4637 | struct cgroup *old_cgrp = | |
4638 | rcu_dereference_raw(cg->subsys[i])->cgroup; | |
4639 | struct cgroup *cgrp = task_cgroup(tsk, i); | |
761b3ef5 | 4640 | ss->exit(cgrp, old_cgrp, tsk); |
d41d5a01 PZ |
4641 | } |
4642 | } | |
4643 | } | |
b4f48b63 | 4644 | task_unlock(tsk); |
d41d5a01 | 4645 | |
817929ec | 4646 | if (cg) |
81a6a5cd | 4647 | put_css_set_taskexit(cg); |
b4f48b63 | 4648 | } |
697f4161 | 4649 | |
a043e3b2 | 4650 | /** |
313e924c | 4651 | * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp |
a043e3b2 | 4652 | * @cgrp: the cgroup in question |
313e924c | 4653 | * @task: the task in question |
a043e3b2 | 4654 | * |
313e924c GN |
4655 | * See if @cgrp is a descendant of @task's cgroup in the appropriate |
4656 | * hierarchy. | |
697f4161 PM |
4657 | * |
4658 | * If we are sending in dummytop, then presumably we are creating | |
4659 | * the top cgroup in the subsystem. | |
4660 | * | |
4661 | * Called only by the ns (nsproxy) cgroup. | |
4662 | */ | |
313e924c | 4663 | int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task) |
697f4161 PM |
4664 | { |
4665 | int ret; | |
4666 | struct cgroup *target; | |
697f4161 | 4667 | |
bd89aabc | 4668 | if (cgrp == dummytop) |
697f4161 PM |
4669 | return 1; |
4670 | ||
7717f7ba | 4671 | target = task_cgroup_from_root(task, cgrp->root); |
bd89aabc PM |
4672 | while (cgrp != target && cgrp!= cgrp->top_cgroup) |
4673 | cgrp = cgrp->parent; | |
4674 | ret = (cgrp == target); | |
697f4161 PM |
4675 | return ret; |
4676 | } | |
81a6a5cd | 4677 | |
bd89aabc | 4678 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd PM |
4679 | { |
4680 | /* All of these checks rely on RCU to keep the cgroup | |
4681 | * structure alive */ | |
bd89aabc PM |
4682 | if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count) |
4683 | && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) { | |
81a6a5cd PM |
4684 | /* Control Group is currently removeable. If it's not |
4685 | * already queued for a userspace notification, queue | |
4686 | * it now */ | |
4687 | int need_schedule_work = 0; | |
cdcc136f | 4688 | raw_spin_lock(&release_list_lock); |
bd89aabc PM |
4689 | if (!cgroup_is_removed(cgrp) && |
4690 | list_empty(&cgrp->release_list)) { | |
4691 | list_add(&cgrp->release_list, &release_list); | |
81a6a5cd PM |
4692 | need_schedule_work = 1; |
4693 | } | |
cdcc136f | 4694 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
4695 | if (need_schedule_work) |
4696 | schedule_work(&release_agent_work); | |
4697 | } | |
4698 | } | |
4699 | ||
d7b9fff7 DN |
4700 | /* Caller must verify that the css is not for root cgroup */ |
4701 | void __css_put(struct cgroup_subsys_state *css, int count) | |
81a6a5cd | 4702 | { |
bd89aabc | 4703 | struct cgroup *cgrp = css->cgroup; |
3dece834 | 4704 | int val; |
81a6a5cd | 4705 | rcu_read_lock(); |
d7b9fff7 | 4706 | val = atomic_sub_return(count, &css->refcnt); |
3dece834 | 4707 | if (val == 1) { |
ec64f515 KH |
4708 | if (notify_on_release(cgrp)) { |
4709 | set_bit(CGRP_RELEASABLE, &cgrp->flags); | |
4710 | check_for_release(cgrp); | |
4711 | } | |
88703267 | 4712 | cgroup_wakeup_rmdir_waiter(cgrp); |
81a6a5cd PM |
4713 | } |
4714 | rcu_read_unlock(); | |
3dece834 | 4715 | WARN_ON_ONCE(val < 1); |
81a6a5cd | 4716 | } |
67523c48 | 4717 | EXPORT_SYMBOL_GPL(__css_put); |
81a6a5cd PM |
4718 | |
4719 | /* | |
4720 | * Notify userspace when a cgroup is released, by running the | |
4721 | * configured release agent with the name of the cgroup (path | |
4722 | * relative to the root of cgroup file system) as the argument. | |
4723 | * | |
4724 | * Most likely, this user command will try to rmdir this cgroup. | |
4725 | * | |
4726 | * This races with the possibility that some other task will be | |
4727 | * attached to this cgroup before it is removed, or that some other | |
4728 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
4729 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
4730 | * unused, and this cgroup will be reprieved from its death sentence, | |
4731 | * to continue to serve a useful existence. Next time it's released, | |
4732 | * we will get notified again, if it still has 'notify_on_release' set. | |
4733 | * | |
4734 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
4735 | * means only wait until the task is successfully execve()'d. The | |
4736 | * separate release agent task is forked by call_usermodehelper(), | |
4737 | * then control in this thread returns here, without waiting for the | |
4738 | * release agent task. We don't bother to wait because the caller of | |
4739 | * this routine has no use for the exit status of the release agent | |
4740 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 4741 | */ |
81a6a5cd PM |
4742 | static void cgroup_release_agent(struct work_struct *work) |
4743 | { | |
4744 | BUG_ON(work != &release_agent_work); | |
4745 | mutex_lock(&cgroup_mutex); | |
cdcc136f | 4746 | raw_spin_lock(&release_list_lock); |
81a6a5cd PM |
4747 | while (!list_empty(&release_list)) { |
4748 | char *argv[3], *envp[3]; | |
4749 | int i; | |
e788e066 | 4750 | char *pathbuf = NULL, *agentbuf = NULL; |
bd89aabc | 4751 | struct cgroup *cgrp = list_entry(release_list.next, |
81a6a5cd PM |
4752 | struct cgroup, |
4753 | release_list); | |
bd89aabc | 4754 | list_del_init(&cgrp->release_list); |
cdcc136f | 4755 | raw_spin_unlock(&release_list_lock); |
81a6a5cd | 4756 | pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); |
e788e066 PM |
4757 | if (!pathbuf) |
4758 | goto continue_free; | |
4759 | if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) | |
4760 | goto continue_free; | |
4761 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
4762 | if (!agentbuf) | |
4763 | goto continue_free; | |
81a6a5cd PM |
4764 | |
4765 | i = 0; | |
e788e066 PM |
4766 | argv[i++] = agentbuf; |
4767 | argv[i++] = pathbuf; | |
81a6a5cd PM |
4768 | argv[i] = NULL; |
4769 | ||
4770 | i = 0; | |
4771 | /* minimal command environment */ | |
4772 | envp[i++] = "HOME=/"; | |
4773 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
4774 | envp[i] = NULL; | |
4775 | ||
4776 | /* Drop the lock while we invoke the usermode helper, | |
4777 | * since the exec could involve hitting disk and hence | |
4778 | * be a slow process */ | |
4779 | mutex_unlock(&cgroup_mutex); | |
4780 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
81a6a5cd | 4781 | mutex_lock(&cgroup_mutex); |
e788e066 PM |
4782 | continue_free: |
4783 | kfree(pathbuf); | |
4784 | kfree(agentbuf); | |
cdcc136f | 4785 | raw_spin_lock(&release_list_lock); |
81a6a5cd | 4786 | } |
cdcc136f | 4787 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
4788 | mutex_unlock(&cgroup_mutex); |
4789 | } | |
8bab8dde PM |
4790 | |
4791 | static int __init cgroup_disable(char *str) | |
4792 | { | |
4793 | int i; | |
4794 | char *token; | |
4795 | ||
4796 | while ((token = strsep(&str, ",")) != NULL) { | |
4797 | if (!*token) | |
4798 | continue; | |
aae8aab4 BB |
4799 | /* |
4800 | * cgroup_disable, being at boot time, can't know about module | |
4801 | * subsystems, so we don't worry about them. | |
4802 | */ | |
4803 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
8bab8dde PM |
4804 | struct cgroup_subsys *ss = subsys[i]; |
4805 | ||
4806 | if (!strcmp(token, ss->name)) { | |
4807 | ss->disabled = 1; | |
4808 | printk(KERN_INFO "Disabling %s control group" | |
4809 | " subsystem\n", ss->name); | |
4810 | break; | |
4811 | } | |
4812 | } | |
4813 | } | |
4814 | return 1; | |
4815 | } | |
4816 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 KH |
4817 | |
4818 | /* | |
4819 | * Functons for CSS ID. | |
4820 | */ | |
4821 | ||
4822 | /* | |
4823 | *To get ID other than 0, this should be called when !cgroup_is_removed(). | |
4824 | */ | |
4825 | unsigned short css_id(struct cgroup_subsys_state *css) | |
4826 | { | |
7f0f1546 KH |
4827 | struct css_id *cssid; |
4828 | ||
4829 | /* | |
4830 | * This css_id() can return correct value when somone has refcnt | |
4831 | * on this or this is under rcu_read_lock(). Once css->id is allocated, | |
4832 | * it's unchanged until freed. | |
4833 | */ | |
d8bf4ca9 | 4834 | cssid = rcu_dereference_check(css->id, atomic_read(&css->refcnt)); |
38460b48 KH |
4835 | |
4836 | if (cssid) | |
4837 | return cssid->id; | |
4838 | return 0; | |
4839 | } | |
67523c48 | 4840 | EXPORT_SYMBOL_GPL(css_id); |
38460b48 KH |
4841 | |
4842 | unsigned short css_depth(struct cgroup_subsys_state *css) | |
4843 | { | |
7f0f1546 KH |
4844 | struct css_id *cssid; |
4845 | ||
d8bf4ca9 | 4846 | cssid = rcu_dereference_check(css->id, atomic_read(&css->refcnt)); |
38460b48 KH |
4847 | |
4848 | if (cssid) | |
4849 | return cssid->depth; | |
4850 | return 0; | |
4851 | } | |
67523c48 | 4852 | EXPORT_SYMBOL_GPL(css_depth); |
38460b48 | 4853 | |
747388d7 KH |
4854 | /** |
4855 | * css_is_ancestor - test "root" css is an ancestor of "child" | |
4856 | * @child: the css to be tested. | |
4857 | * @root: the css supporsed to be an ancestor of the child. | |
4858 | * | |
4859 | * Returns true if "root" is an ancestor of "child" in its hierarchy. Because | |
4860 | * this function reads css->id, this use rcu_dereference() and rcu_read_lock(). | |
4861 | * But, considering usual usage, the csses should be valid objects after test. | |
4862 | * Assuming that the caller will do some action to the child if this returns | |
4863 | * returns true, the caller must take "child";s reference count. | |
4864 | * If "child" is valid object and this returns true, "root" is valid, too. | |
4865 | */ | |
4866 | ||
38460b48 | 4867 | bool css_is_ancestor(struct cgroup_subsys_state *child, |
0b7f569e | 4868 | const struct cgroup_subsys_state *root) |
38460b48 | 4869 | { |
747388d7 KH |
4870 | struct css_id *child_id; |
4871 | struct css_id *root_id; | |
4872 | bool ret = true; | |
38460b48 | 4873 | |
747388d7 KH |
4874 | rcu_read_lock(); |
4875 | child_id = rcu_dereference(child->id); | |
4876 | root_id = rcu_dereference(root->id); | |
4877 | if (!child_id | |
4878 | || !root_id | |
4879 | || (child_id->depth < root_id->depth) | |
4880 | || (child_id->stack[root_id->depth] != root_id->id)) | |
4881 | ret = false; | |
4882 | rcu_read_unlock(); | |
4883 | return ret; | |
38460b48 KH |
4884 | } |
4885 | ||
38460b48 KH |
4886 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) |
4887 | { | |
4888 | struct css_id *id = css->id; | |
4889 | /* When this is called before css_id initialization, id can be NULL */ | |
4890 | if (!id) | |
4891 | return; | |
4892 | ||
4893 | BUG_ON(!ss->use_id); | |
4894 | ||
4895 | rcu_assign_pointer(id->css, NULL); | |
4896 | rcu_assign_pointer(css->id, NULL); | |
42aee6c4 | 4897 | spin_lock(&ss->id_lock); |
38460b48 | 4898 | idr_remove(&ss->idr, id->id); |
42aee6c4 | 4899 | spin_unlock(&ss->id_lock); |
025cea99 | 4900 | kfree_rcu(id, rcu_head); |
38460b48 | 4901 | } |
67523c48 | 4902 | EXPORT_SYMBOL_GPL(free_css_id); |
38460b48 KH |
4903 | |
4904 | /* | |
4905 | * This is called by init or create(). Then, calls to this function are | |
4906 | * always serialized (By cgroup_mutex() at create()). | |
4907 | */ | |
4908 | ||
4909 | static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) | |
4910 | { | |
4911 | struct css_id *newid; | |
4912 | int myid, error, size; | |
4913 | ||
4914 | BUG_ON(!ss->use_id); | |
4915 | ||
4916 | size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); | |
4917 | newid = kzalloc(size, GFP_KERNEL); | |
4918 | if (!newid) | |
4919 | return ERR_PTR(-ENOMEM); | |
4920 | /* get id */ | |
4921 | if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) { | |
4922 | error = -ENOMEM; | |
4923 | goto err_out; | |
4924 | } | |
42aee6c4 | 4925 | spin_lock(&ss->id_lock); |
38460b48 KH |
4926 | /* Don't use 0. allocates an ID of 1-65535 */ |
4927 | error = idr_get_new_above(&ss->idr, newid, 1, &myid); | |
42aee6c4 | 4928 | spin_unlock(&ss->id_lock); |
38460b48 KH |
4929 | |
4930 | /* Returns error when there are no free spaces for new ID.*/ | |
4931 | if (error) { | |
4932 | error = -ENOSPC; | |
4933 | goto err_out; | |
4934 | } | |
4935 | if (myid > CSS_ID_MAX) | |
4936 | goto remove_idr; | |
4937 | ||
4938 | newid->id = myid; | |
4939 | newid->depth = depth; | |
4940 | return newid; | |
4941 | remove_idr: | |
4942 | error = -ENOSPC; | |
42aee6c4 | 4943 | spin_lock(&ss->id_lock); |
38460b48 | 4944 | idr_remove(&ss->idr, myid); |
42aee6c4 | 4945 | spin_unlock(&ss->id_lock); |
38460b48 KH |
4946 | err_out: |
4947 | kfree(newid); | |
4948 | return ERR_PTR(error); | |
4949 | ||
4950 | } | |
4951 | ||
e6a1105b BB |
4952 | static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, |
4953 | struct cgroup_subsys_state *rootcss) | |
38460b48 KH |
4954 | { |
4955 | struct css_id *newid; | |
38460b48 | 4956 | |
42aee6c4 | 4957 | spin_lock_init(&ss->id_lock); |
38460b48 KH |
4958 | idr_init(&ss->idr); |
4959 | ||
38460b48 KH |
4960 | newid = get_new_cssid(ss, 0); |
4961 | if (IS_ERR(newid)) | |
4962 | return PTR_ERR(newid); | |
4963 | ||
4964 | newid->stack[0] = newid->id; | |
4965 | newid->css = rootcss; | |
4966 | rootcss->id = newid; | |
4967 | return 0; | |
4968 | } | |
4969 | ||
4970 | static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, | |
4971 | struct cgroup *child) | |
4972 | { | |
4973 | int subsys_id, i, depth = 0; | |
4974 | struct cgroup_subsys_state *parent_css, *child_css; | |
fae9c791 | 4975 | struct css_id *child_id, *parent_id; |
38460b48 KH |
4976 | |
4977 | subsys_id = ss->subsys_id; | |
4978 | parent_css = parent->subsys[subsys_id]; | |
4979 | child_css = child->subsys[subsys_id]; | |
38460b48 | 4980 | parent_id = parent_css->id; |
94b3dd0f | 4981 | depth = parent_id->depth + 1; |
38460b48 KH |
4982 | |
4983 | child_id = get_new_cssid(ss, depth); | |
4984 | if (IS_ERR(child_id)) | |
4985 | return PTR_ERR(child_id); | |
4986 | ||
4987 | for (i = 0; i < depth; i++) | |
4988 | child_id->stack[i] = parent_id->stack[i]; | |
4989 | child_id->stack[depth] = child_id->id; | |
4990 | /* | |
4991 | * child_id->css pointer will be set after this cgroup is available | |
4992 | * see cgroup_populate_dir() | |
4993 | */ | |
4994 | rcu_assign_pointer(child_css->id, child_id); | |
4995 | ||
4996 | return 0; | |
4997 | } | |
4998 | ||
4999 | /** | |
5000 | * css_lookup - lookup css by id | |
5001 | * @ss: cgroup subsys to be looked into. | |
5002 | * @id: the id | |
5003 | * | |
5004 | * Returns pointer to cgroup_subsys_state if there is valid one with id. | |
5005 | * NULL if not. Should be called under rcu_read_lock() | |
5006 | */ | |
5007 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) | |
5008 | { | |
5009 | struct css_id *cssid = NULL; | |
5010 | ||
5011 | BUG_ON(!ss->use_id); | |
5012 | cssid = idr_find(&ss->idr, id); | |
5013 | ||
5014 | if (unlikely(!cssid)) | |
5015 | return NULL; | |
5016 | ||
5017 | return rcu_dereference(cssid->css); | |
5018 | } | |
67523c48 | 5019 | EXPORT_SYMBOL_GPL(css_lookup); |
38460b48 KH |
5020 | |
5021 | /** | |
5022 | * css_get_next - lookup next cgroup under specified hierarchy. | |
5023 | * @ss: pointer to subsystem | |
5024 | * @id: current position of iteration. | |
5025 | * @root: pointer to css. search tree under this. | |
5026 | * @foundid: position of found object. | |
5027 | * | |
5028 | * Search next css under the specified hierarchy of rootid. Calling under | |
5029 | * rcu_read_lock() is necessary. Returns NULL if it reaches the end. | |
5030 | */ | |
5031 | struct cgroup_subsys_state * | |
5032 | css_get_next(struct cgroup_subsys *ss, int id, | |
5033 | struct cgroup_subsys_state *root, int *foundid) | |
5034 | { | |
5035 | struct cgroup_subsys_state *ret = NULL; | |
5036 | struct css_id *tmp; | |
5037 | int tmpid; | |
5038 | int rootid = css_id(root); | |
5039 | int depth = css_depth(root); | |
5040 | ||
5041 | if (!rootid) | |
5042 | return NULL; | |
5043 | ||
5044 | BUG_ON(!ss->use_id); | |
ca464d69 HD |
5045 | WARN_ON_ONCE(!rcu_read_lock_held()); |
5046 | ||
38460b48 KH |
5047 | /* fill start point for scan */ |
5048 | tmpid = id; | |
5049 | while (1) { | |
5050 | /* | |
5051 | * scan next entry from bitmap(tree), tmpid is updated after | |
5052 | * idr_get_next(). | |
5053 | */ | |
38460b48 | 5054 | tmp = idr_get_next(&ss->idr, &tmpid); |
38460b48 KH |
5055 | if (!tmp) |
5056 | break; | |
5057 | if (tmp->depth >= depth && tmp->stack[depth] == rootid) { | |
5058 | ret = rcu_dereference(tmp->css); | |
5059 | if (ret) { | |
5060 | *foundid = tmpid; | |
5061 | break; | |
5062 | } | |
5063 | } | |
5064 | /* continue to scan from next id */ | |
5065 | tmpid = tmpid + 1; | |
5066 | } | |
5067 | return ret; | |
5068 | } | |
5069 | ||
e5d1367f SE |
5070 | /* |
5071 | * get corresponding css from file open on cgroupfs directory | |
5072 | */ | |
5073 | struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) | |
5074 | { | |
5075 | struct cgroup *cgrp; | |
5076 | struct inode *inode; | |
5077 | struct cgroup_subsys_state *css; | |
5078 | ||
5079 | inode = f->f_dentry->d_inode; | |
5080 | /* check in cgroup filesystem dir */ | |
5081 | if (inode->i_op != &cgroup_dir_inode_operations) | |
5082 | return ERR_PTR(-EBADF); | |
5083 | ||
5084 | if (id < 0 || id >= CGROUP_SUBSYS_COUNT) | |
5085 | return ERR_PTR(-EINVAL); | |
5086 | ||
5087 | /* get cgroup */ | |
5088 | cgrp = __d_cgrp(f->f_dentry); | |
5089 | css = cgrp->subsys[id]; | |
5090 | return css ? css : ERR_PTR(-ENOENT); | |
5091 | } | |
5092 | ||
fe693435 | 5093 | #ifdef CONFIG_CGROUP_DEBUG |
761b3ef5 | 5094 | static struct cgroup_subsys_state *debug_create(struct cgroup *cont) |
fe693435 PM |
5095 | { |
5096 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5097 | ||
5098 | if (!css) | |
5099 | return ERR_PTR(-ENOMEM); | |
5100 | ||
5101 | return css; | |
5102 | } | |
5103 | ||
761b3ef5 | 5104 | static void debug_destroy(struct cgroup *cont) |
fe693435 PM |
5105 | { |
5106 | kfree(cont->subsys[debug_subsys_id]); | |
5107 | } | |
5108 | ||
5109 | static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft) | |
5110 | { | |
5111 | return atomic_read(&cont->count); | |
5112 | } | |
5113 | ||
5114 | static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft) | |
5115 | { | |
5116 | return cgroup_task_count(cont); | |
5117 | } | |
5118 | ||
5119 | static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft) | |
5120 | { | |
5121 | return (u64)(unsigned long)current->cgroups; | |
5122 | } | |
5123 | ||
5124 | static u64 current_css_set_refcount_read(struct cgroup *cont, | |
5125 | struct cftype *cft) | |
5126 | { | |
5127 | u64 count; | |
5128 | ||
5129 | rcu_read_lock(); | |
5130 | count = atomic_read(¤t->cgroups->refcount); | |
5131 | rcu_read_unlock(); | |
5132 | return count; | |
5133 | } | |
5134 | ||
7717f7ba PM |
5135 | static int current_css_set_cg_links_read(struct cgroup *cont, |
5136 | struct cftype *cft, | |
5137 | struct seq_file *seq) | |
5138 | { | |
5139 | struct cg_cgroup_link *link; | |
5140 | struct css_set *cg; | |
5141 | ||
5142 | read_lock(&css_set_lock); | |
5143 | rcu_read_lock(); | |
5144 | cg = rcu_dereference(current->cgroups); | |
5145 | list_for_each_entry(link, &cg->cg_links, cg_link_list) { | |
5146 | struct cgroup *c = link->cgrp; | |
5147 | const char *name; | |
5148 | ||
5149 | if (c->dentry) | |
5150 | name = c->dentry->d_name.name; | |
5151 | else | |
5152 | name = "?"; | |
2c6ab6d2 PM |
5153 | seq_printf(seq, "Root %d group %s\n", |
5154 | c->root->hierarchy_id, name); | |
7717f7ba PM |
5155 | } |
5156 | rcu_read_unlock(); | |
5157 | read_unlock(&css_set_lock); | |
5158 | return 0; | |
5159 | } | |
5160 | ||
5161 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
5162 | static int cgroup_css_links_read(struct cgroup *cont, | |
5163 | struct cftype *cft, | |
5164 | struct seq_file *seq) | |
5165 | { | |
5166 | struct cg_cgroup_link *link; | |
5167 | ||
5168 | read_lock(&css_set_lock); | |
5169 | list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { | |
5170 | struct css_set *cg = link->cg; | |
5171 | struct task_struct *task; | |
5172 | int count = 0; | |
5173 | seq_printf(seq, "css_set %p\n", cg); | |
5174 | list_for_each_entry(task, &cg->tasks, cg_list) { | |
5175 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) { | |
5176 | seq_puts(seq, " ...\n"); | |
5177 | break; | |
5178 | } else { | |
5179 | seq_printf(seq, " task %d\n", | |
5180 | task_pid_vnr(task)); | |
5181 | } | |
5182 | } | |
5183 | } | |
5184 | read_unlock(&css_set_lock); | |
5185 | return 0; | |
5186 | } | |
5187 | ||
fe693435 PM |
5188 | static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft) |
5189 | { | |
5190 | return test_bit(CGRP_RELEASABLE, &cgrp->flags); | |
5191 | } | |
5192 | ||
5193 | static struct cftype debug_files[] = { | |
5194 | { | |
5195 | .name = "cgroup_refcount", | |
5196 | .read_u64 = cgroup_refcount_read, | |
5197 | }, | |
5198 | { | |
5199 | .name = "taskcount", | |
5200 | .read_u64 = debug_taskcount_read, | |
5201 | }, | |
5202 | ||
5203 | { | |
5204 | .name = "current_css_set", | |
5205 | .read_u64 = current_css_set_read, | |
5206 | }, | |
5207 | ||
5208 | { | |
5209 | .name = "current_css_set_refcount", | |
5210 | .read_u64 = current_css_set_refcount_read, | |
5211 | }, | |
5212 | ||
7717f7ba PM |
5213 | { |
5214 | .name = "current_css_set_cg_links", | |
5215 | .read_seq_string = current_css_set_cg_links_read, | |
5216 | }, | |
5217 | ||
5218 | { | |
5219 | .name = "cgroup_css_links", | |
5220 | .read_seq_string = cgroup_css_links_read, | |
5221 | }, | |
5222 | ||
fe693435 PM |
5223 | { |
5224 | .name = "releasable", | |
5225 | .read_u64 = releasable_read, | |
5226 | }, | |
5227 | }; | |
5228 | ||
5229 | static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont) | |
5230 | { | |
5231 | return cgroup_add_files(cont, ss, debug_files, | |
5232 | ARRAY_SIZE(debug_files)); | |
5233 | } | |
5234 | ||
5235 | struct cgroup_subsys debug_subsys = { | |
5236 | .name = "debug", | |
5237 | .create = debug_create, | |
5238 | .destroy = debug_destroy, | |
5239 | .populate = debug_populate, | |
5240 | .subsys_id = debug_subsys_id, | |
5241 | }; | |
5242 | #endif /* CONFIG_CGROUP_DEBUG */ |