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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 | * | |
7 | * Copyright notices from the original cpuset code: | |
8 | * -------------------------------------------------- | |
9 | * Copyright (C) 2003 BULL SA. | |
10 | * Copyright (C) 2004-2006 Silicon Graphics, Inc. | |
11 | * | |
12 | * Portions derived from Patrick Mochel's sysfs code. | |
13 | * sysfs is Copyright (c) 2001-3 Patrick Mochel | |
14 | * | |
15 | * 2003-10-10 Written by Simon Derr. | |
16 | * 2003-10-22 Updates by Stephen Hemminger. | |
17 | * 2004 May-July Rework by Paul Jackson. | |
18 | * --------------------------------------------------- | |
19 | * | |
20 | * This file is subject to the terms and conditions of the GNU General Public | |
21 | * License. See the file COPYING in the main directory of the Linux | |
22 | * distribution for more details. | |
23 | */ | |
24 | ||
25 | #include <linux/cgroup.h> | |
26 | #include <linux/errno.h> | |
27 | #include <linux/fs.h> | |
28 | #include <linux/kernel.h> | |
29 | #include <linux/list.h> | |
30 | #include <linux/mm.h> | |
31 | #include <linux/mutex.h> | |
32 | #include <linux/mount.h> | |
33 | #include <linux/pagemap.h> | |
a424316c | 34 | #include <linux/proc_fs.h> |
ddbcc7e8 PM |
35 | #include <linux/rcupdate.h> |
36 | #include <linux/sched.h> | |
817929ec | 37 | #include <linux/backing-dev.h> |
ddbcc7e8 PM |
38 | #include <linux/seq_file.h> |
39 | #include <linux/slab.h> | |
40 | #include <linux/magic.h> | |
41 | #include <linux/spinlock.h> | |
42 | #include <linux/string.h> | |
bbcb81d0 | 43 | #include <linux/sort.h> |
81a6a5cd | 44 | #include <linux/kmod.h> |
846c7bb0 BS |
45 | #include <linux/delayacct.h> |
46 | #include <linux/cgroupstats.h> | |
472b1053 | 47 | #include <linux/hash.h> |
3f8206d4 | 48 | #include <linux/namei.h> |
846c7bb0 | 49 | |
ddbcc7e8 PM |
50 | #include <asm/atomic.h> |
51 | ||
81a6a5cd PM |
52 | static DEFINE_MUTEX(cgroup_mutex); |
53 | ||
ddbcc7e8 PM |
54 | /* Generate an array of cgroup subsystem pointers */ |
55 | #define SUBSYS(_x) &_x ## _subsys, | |
56 | ||
57 | static struct cgroup_subsys *subsys[] = { | |
58 | #include <linux/cgroup_subsys.h> | |
59 | }; | |
60 | ||
61 | /* | |
62 | * A cgroupfs_root represents the root of a cgroup hierarchy, | |
63 | * and may be associated with a superblock to form an active | |
64 | * hierarchy | |
65 | */ | |
66 | struct cgroupfs_root { | |
67 | struct super_block *sb; | |
68 | ||
69 | /* | |
70 | * The bitmask of subsystems intended to be attached to this | |
71 | * hierarchy | |
72 | */ | |
73 | unsigned long subsys_bits; | |
74 | ||
75 | /* The bitmask of subsystems currently attached to this hierarchy */ | |
76 | unsigned long actual_subsys_bits; | |
77 | ||
78 | /* A list running through the attached subsystems */ | |
79 | struct list_head subsys_list; | |
80 | ||
81 | /* The root cgroup for this hierarchy */ | |
82 | struct cgroup top_cgroup; | |
83 | ||
84 | /* Tracks how many cgroups are currently defined in hierarchy.*/ | |
85 | int number_of_cgroups; | |
86 | ||
e5f6a860 | 87 | /* A list running through the active hierarchies */ |
ddbcc7e8 PM |
88 | struct list_head root_list; |
89 | ||
90 | /* Hierarchy-specific flags */ | |
91 | unsigned long flags; | |
81a6a5cd | 92 | |
e788e066 | 93 | /* The path to use for release notifications. */ |
81a6a5cd | 94 | char release_agent_path[PATH_MAX]; |
ddbcc7e8 PM |
95 | }; |
96 | ||
ddbcc7e8 PM |
97 | /* |
98 | * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the | |
99 | * subsystems that are otherwise unattached - it never has more than a | |
100 | * single cgroup, and all tasks are part of that cgroup. | |
101 | */ | |
102 | static struct cgroupfs_root rootnode; | |
103 | ||
38460b48 KH |
104 | /* |
105 | * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when | |
106 | * cgroup_subsys->use_id != 0. | |
107 | */ | |
108 | #define CSS_ID_MAX (65535) | |
109 | struct css_id { | |
110 | /* | |
111 | * The css to which this ID points. This pointer is set to valid value | |
112 | * after cgroup is populated. If cgroup is removed, this will be NULL. | |
113 | * This pointer is expected to be RCU-safe because destroy() | |
114 | * is called after synchronize_rcu(). But for safe use, css_is_removed() | |
115 | * css_tryget() should be used for avoiding race. | |
116 | */ | |
117 | struct cgroup_subsys_state *css; | |
118 | /* | |
119 | * ID of this css. | |
120 | */ | |
121 | unsigned short id; | |
122 | /* | |
123 | * Depth in hierarchy which this ID belongs to. | |
124 | */ | |
125 | unsigned short depth; | |
126 | /* | |
127 | * ID is freed by RCU. (and lookup routine is RCU safe.) | |
128 | */ | |
129 | struct rcu_head rcu_head; | |
130 | /* | |
131 | * Hierarchy of CSS ID belongs to. | |
132 | */ | |
133 | unsigned short stack[0]; /* Array of Length (depth+1) */ | |
134 | }; | |
135 | ||
136 | ||
ddbcc7e8 PM |
137 | /* The list of hierarchy roots */ |
138 | ||
139 | static LIST_HEAD(roots); | |
817929ec | 140 | static int root_count; |
ddbcc7e8 PM |
141 | |
142 | /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ | |
143 | #define dummytop (&rootnode.top_cgroup) | |
144 | ||
145 | /* This flag indicates whether tasks in the fork and exit paths should | |
a043e3b2 LZ |
146 | * check for fork/exit handlers to call. This avoids us having to do |
147 | * extra work in the fork/exit path if none of the subsystems need to | |
148 | * be called. | |
ddbcc7e8 | 149 | */ |
8947f9d5 | 150 | static int need_forkexit_callback __read_mostly; |
ddbcc7e8 | 151 | |
ddbcc7e8 | 152 | /* convenient tests for these bits */ |
bd89aabc | 153 | inline int cgroup_is_removed(const struct cgroup *cgrp) |
ddbcc7e8 | 154 | { |
bd89aabc | 155 | return test_bit(CGRP_REMOVED, &cgrp->flags); |
ddbcc7e8 PM |
156 | } |
157 | ||
158 | /* bits in struct cgroupfs_root flags field */ | |
159 | enum { | |
160 | ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ | |
161 | }; | |
162 | ||
e9685a03 | 163 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
81a6a5cd PM |
164 | { |
165 | const int bits = | |
bd89aabc PM |
166 | (1 << CGRP_RELEASABLE) | |
167 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
168 | return (cgrp->flags & bits) == bits; | |
81a6a5cd PM |
169 | } |
170 | ||
e9685a03 | 171 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 172 | { |
bd89aabc | 173 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
174 | } |
175 | ||
ddbcc7e8 PM |
176 | /* |
177 | * for_each_subsys() allows you to iterate on each subsystem attached to | |
178 | * an active hierarchy | |
179 | */ | |
180 | #define for_each_subsys(_root, _ss) \ | |
181 | list_for_each_entry(_ss, &_root->subsys_list, sibling) | |
182 | ||
e5f6a860 LZ |
183 | /* for_each_active_root() allows you to iterate across the active hierarchies */ |
184 | #define for_each_active_root(_root) \ | |
ddbcc7e8 PM |
185 | list_for_each_entry(_root, &roots, root_list) |
186 | ||
81a6a5cd PM |
187 | /* the list of cgroups eligible for automatic release. Protected by |
188 | * release_list_lock */ | |
189 | static LIST_HEAD(release_list); | |
190 | static DEFINE_SPINLOCK(release_list_lock); | |
191 | static void cgroup_release_agent(struct work_struct *work); | |
192 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
bd89aabc | 193 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 194 | |
817929ec PM |
195 | /* Link structure for associating css_set objects with cgroups */ |
196 | struct cg_cgroup_link { | |
197 | /* | |
198 | * List running through cg_cgroup_links associated with a | |
199 | * cgroup, anchored on cgroup->css_sets | |
200 | */ | |
bd89aabc | 201 | struct list_head cgrp_link_list; |
817929ec PM |
202 | /* |
203 | * List running through cg_cgroup_links pointing at a | |
204 | * single css_set object, anchored on css_set->cg_links | |
205 | */ | |
206 | struct list_head cg_link_list; | |
207 | struct css_set *cg; | |
208 | }; | |
209 | ||
210 | /* The default css_set - used by init and its children prior to any | |
211 | * hierarchies being mounted. It contains a pointer to the root state | |
212 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
213 | * reference-counted, to improve performance when child cgroups | |
214 | * haven't been created. | |
215 | */ | |
216 | ||
217 | static struct css_set init_css_set; | |
218 | static struct cg_cgroup_link init_css_set_link; | |
219 | ||
38460b48 KH |
220 | static int cgroup_subsys_init_idr(struct cgroup_subsys *ss); |
221 | ||
817929ec PM |
222 | /* css_set_lock protects the list of css_set objects, and the |
223 | * chain of tasks off each css_set. Nests outside task->alloc_lock | |
224 | * due to cgroup_iter_start() */ | |
225 | static DEFINE_RWLOCK(css_set_lock); | |
226 | static int css_set_count; | |
227 | ||
472b1053 LZ |
228 | /* hash table for cgroup groups. This improves the performance to |
229 | * find an existing css_set */ | |
230 | #define CSS_SET_HASH_BITS 7 | |
231 | #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS) | |
232 | static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE]; | |
233 | ||
234 | static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) | |
235 | { | |
236 | int i; | |
237 | int index; | |
238 | unsigned long tmp = 0UL; | |
239 | ||
240 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) | |
241 | tmp += (unsigned long)css[i]; | |
242 | tmp = (tmp >> 16) ^ tmp; | |
243 | ||
244 | index = hash_long(tmp, CSS_SET_HASH_BITS); | |
245 | ||
246 | return &css_set_table[index]; | |
247 | } | |
248 | ||
817929ec PM |
249 | /* We don't maintain the lists running through each css_set to its |
250 | * task until after the first call to cgroup_iter_start(). This | |
251 | * reduces the fork()/exit() overhead for people who have cgroups | |
252 | * compiled into their kernel but not actually in use */ | |
8947f9d5 | 253 | static int use_task_css_set_links __read_mostly; |
817929ec PM |
254 | |
255 | /* When we create or destroy a css_set, the operation simply | |
256 | * takes/releases a reference count on all the cgroups referenced | |
257 | * by subsystems in this css_set. This can end up multiple-counting | |
258 | * some cgroups, but that's OK - the ref-count is just a | |
259 | * busy/not-busy indicator; ensuring that we only count each cgroup | |
260 | * once would require taking a global lock to ensure that no | |
b4f48b63 PM |
261 | * subsystems moved between hierarchies while we were doing so. |
262 | * | |
263 | * Possible TODO: decide at boot time based on the number of | |
264 | * registered subsystems and the number of CPUs or NUMA nodes whether | |
265 | * it's better for performance to ref-count every subsystem, or to | |
266 | * take a global lock and only add one ref count to each hierarchy. | |
267 | */ | |
817929ec PM |
268 | |
269 | /* | |
270 | * unlink a css_set from the list and free it | |
271 | */ | |
81a6a5cd | 272 | static void unlink_css_set(struct css_set *cg) |
b4f48b63 | 273 | { |
71cbb949 KM |
274 | struct cg_cgroup_link *link; |
275 | struct cg_cgroup_link *saved_link; | |
276 | ||
472b1053 | 277 | hlist_del(&cg->hlist); |
817929ec | 278 | css_set_count--; |
71cbb949 KM |
279 | |
280 | list_for_each_entry_safe(link, saved_link, &cg->cg_links, | |
281 | cg_link_list) { | |
817929ec | 282 | list_del(&link->cg_link_list); |
bd89aabc | 283 | list_del(&link->cgrp_link_list); |
817929ec PM |
284 | kfree(link); |
285 | } | |
81a6a5cd PM |
286 | } |
287 | ||
146aa1bd | 288 | static void __put_css_set(struct css_set *cg, int taskexit) |
81a6a5cd PM |
289 | { |
290 | int i; | |
146aa1bd LJ |
291 | /* |
292 | * Ensure that the refcount doesn't hit zero while any readers | |
293 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
294 | * rwlock | |
295 | */ | |
296 | if (atomic_add_unless(&cg->refcount, -1, 1)) | |
297 | return; | |
298 | write_lock(&css_set_lock); | |
299 | if (!atomic_dec_and_test(&cg->refcount)) { | |
300 | write_unlock(&css_set_lock); | |
301 | return; | |
302 | } | |
81a6a5cd | 303 | unlink_css_set(cg); |
146aa1bd | 304 | write_unlock(&css_set_lock); |
81a6a5cd PM |
305 | |
306 | rcu_read_lock(); | |
307 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
a47295e6 | 308 | struct cgroup *cgrp = rcu_dereference(cg->subsys[i]->cgroup); |
bd89aabc PM |
309 | if (atomic_dec_and_test(&cgrp->count) && |
310 | notify_on_release(cgrp)) { | |
81a6a5cd | 311 | if (taskexit) |
bd89aabc PM |
312 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
313 | check_for_release(cgrp); | |
81a6a5cd PM |
314 | } |
315 | } | |
316 | rcu_read_unlock(); | |
817929ec | 317 | kfree(cg); |
b4f48b63 PM |
318 | } |
319 | ||
817929ec PM |
320 | /* |
321 | * refcounted get/put for css_set objects | |
322 | */ | |
323 | static inline void get_css_set(struct css_set *cg) | |
324 | { | |
146aa1bd | 325 | atomic_inc(&cg->refcount); |
817929ec PM |
326 | } |
327 | ||
328 | static inline void put_css_set(struct css_set *cg) | |
329 | { | |
146aa1bd | 330 | __put_css_set(cg, 0); |
817929ec PM |
331 | } |
332 | ||
81a6a5cd PM |
333 | static inline void put_css_set_taskexit(struct css_set *cg) |
334 | { | |
146aa1bd | 335 | __put_css_set(cg, 1); |
81a6a5cd PM |
336 | } |
337 | ||
817929ec PM |
338 | /* |
339 | * find_existing_css_set() is a helper for | |
340 | * find_css_set(), and checks to see whether an existing | |
472b1053 | 341 | * css_set is suitable. |
817929ec PM |
342 | * |
343 | * oldcg: the cgroup group that we're using before the cgroup | |
344 | * transition | |
345 | * | |
bd89aabc | 346 | * cgrp: the cgroup that we're moving into |
817929ec PM |
347 | * |
348 | * template: location in which to build the desired set of subsystem | |
349 | * state objects for the new cgroup group | |
350 | */ | |
817929ec PM |
351 | static struct css_set *find_existing_css_set( |
352 | struct css_set *oldcg, | |
bd89aabc | 353 | struct cgroup *cgrp, |
817929ec | 354 | struct cgroup_subsys_state *template[]) |
b4f48b63 PM |
355 | { |
356 | int i; | |
bd89aabc | 357 | struct cgroupfs_root *root = cgrp->root; |
472b1053 LZ |
358 | struct hlist_head *hhead; |
359 | struct hlist_node *node; | |
360 | struct css_set *cg; | |
817929ec PM |
361 | |
362 | /* Built the set of subsystem state objects that we want to | |
363 | * see in the new css_set */ | |
364 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
8d53d55d | 365 | if (root->subsys_bits & (1UL << i)) { |
817929ec PM |
366 | /* Subsystem is in this hierarchy. So we want |
367 | * the subsystem state from the new | |
368 | * cgroup */ | |
bd89aabc | 369 | template[i] = cgrp->subsys[i]; |
817929ec PM |
370 | } else { |
371 | /* Subsystem is not in this hierarchy, so we | |
372 | * don't want to change the subsystem state */ | |
373 | template[i] = oldcg->subsys[i]; | |
374 | } | |
375 | } | |
376 | ||
472b1053 LZ |
377 | hhead = css_set_hash(template); |
378 | hlist_for_each_entry(cg, node, hhead, hlist) { | |
817929ec PM |
379 | if (!memcmp(template, cg->subsys, sizeof(cg->subsys))) { |
380 | /* All subsystems matched */ | |
381 | return cg; | |
382 | } | |
472b1053 | 383 | } |
817929ec PM |
384 | |
385 | /* No existing cgroup group matched */ | |
386 | return NULL; | |
387 | } | |
388 | ||
36553434 LZ |
389 | static void free_cg_links(struct list_head *tmp) |
390 | { | |
391 | struct cg_cgroup_link *link; | |
392 | struct cg_cgroup_link *saved_link; | |
393 | ||
394 | list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) { | |
395 | list_del(&link->cgrp_link_list); | |
396 | kfree(link); | |
397 | } | |
398 | } | |
399 | ||
817929ec PM |
400 | /* |
401 | * allocate_cg_links() allocates "count" cg_cgroup_link structures | |
bd89aabc | 402 | * and chains them on tmp through their cgrp_link_list fields. Returns 0 on |
817929ec PM |
403 | * success or a negative error |
404 | */ | |
817929ec PM |
405 | static int allocate_cg_links(int count, struct list_head *tmp) |
406 | { | |
407 | struct cg_cgroup_link *link; | |
408 | int i; | |
409 | INIT_LIST_HEAD(tmp); | |
410 | for (i = 0; i < count; i++) { | |
411 | link = kmalloc(sizeof(*link), GFP_KERNEL); | |
412 | if (!link) { | |
36553434 | 413 | free_cg_links(tmp); |
817929ec PM |
414 | return -ENOMEM; |
415 | } | |
bd89aabc | 416 | list_add(&link->cgrp_link_list, tmp); |
817929ec PM |
417 | } |
418 | return 0; | |
419 | } | |
420 | ||
c12f65d4 LZ |
421 | /** |
422 | * link_css_set - a helper function to link a css_set to a cgroup | |
423 | * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links() | |
424 | * @cg: the css_set to be linked | |
425 | * @cgrp: the destination cgroup | |
426 | */ | |
427 | static void link_css_set(struct list_head *tmp_cg_links, | |
428 | struct css_set *cg, struct cgroup *cgrp) | |
429 | { | |
430 | struct cg_cgroup_link *link; | |
431 | ||
432 | BUG_ON(list_empty(tmp_cg_links)); | |
433 | link = list_first_entry(tmp_cg_links, struct cg_cgroup_link, | |
434 | cgrp_link_list); | |
435 | link->cg = cg; | |
436 | list_move(&link->cgrp_link_list, &cgrp->css_sets); | |
437 | list_add(&link->cg_link_list, &cg->cg_links); | |
438 | } | |
439 | ||
817929ec PM |
440 | /* |
441 | * find_css_set() takes an existing cgroup group and a | |
442 | * cgroup object, and returns a css_set object that's | |
443 | * equivalent to the old group, but with the given cgroup | |
444 | * substituted into the appropriate hierarchy. Must be called with | |
445 | * cgroup_mutex held | |
446 | */ | |
817929ec | 447 | static struct css_set *find_css_set( |
bd89aabc | 448 | struct css_set *oldcg, struct cgroup *cgrp) |
817929ec PM |
449 | { |
450 | struct css_set *res; | |
451 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT]; | |
452 | int i; | |
453 | ||
454 | struct list_head tmp_cg_links; | |
817929ec | 455 | |
472b1053 LZ |
456 | struct hlist_head *hhead; |
457 | ||
817929ec PM |
458 | /* First see if we already have a cgroup group that matches |
459 | * the desired set */ | |
7e9abd89 | 460 | read_lock(&css_set_lock); |
bd89aabc | 461 | res = find_existing_css_set(oldcg, cgrp, template); |
817929ec PM |
462 | if (res) |
463 | get_css_set(res); | |
7e9abd89 | 464 | read_unlock(&css_set_lock); |
817929ec PM |
465 | |
466 | if (res) | |
467 | return res; | |
468 | ||
469 | res = kmalloc(sizeof(*res), GFP_KERNEL); | |
470 | if (!res) | |
471 | return NULL; | |
472 | ||
473 | /* Allocate all the cg_cgroup_link objects that we'll need */ | |
474 | if (allocate_cg_links(root_count, &tmp_cg_links) < 0) { | |
475 | kfree(res); | |
476 | return NULL; | |
477 | } | |
478 | ||
146aa1bd | 479 | atomic_set(&res->refcount, 1); |
817929ec PM |
480 | INIT_LIST_HEAD(&res->cg_links); |
481 | INIT_LIST_HEAD(&res->tasks); | |
472b1053 | 482 | INIT_HLIST_NODE(&res->hlist); |
817929ec PM |
483 | |
484 | /* Copy the set of subsystem state objects generated in | |
485 | * find_existing_css_set() */ | |
486 | memcpy(res->subsys, template, sizeof(res->subsys)); | |
487 | ||
488 | write_lock(&css_set_lock); | |
489 | /* Add reference counts and links from the new css_set. */ | |
490 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
bd89aabc | 491 | struct cgroup *cgrp = res->subsys[i]->cgroup; |
817929ec | 492 | struct cgroup_subsys *ss = subsys[i]; |
bd89aabc | 493 | atomic_inc(&cgrp->count); |
817929ec PM |
494 | /* |
495 | * We want to add a link once per cgroup, so we | |
496 | * only do it for the first subsystem in each | |
497 | * hierarchy | |
498 | */ | |
c12f65d4 LZ |
499 | if (ss->root->subsys_list.next == &ss->sibling) |
500 | link_css_set(&tmp_cg_links, res, cgrp); | |
817929ec | 501 | } |
c12f65d4 LZ |
502 | if (list_empty(&rootnode.subsys_list)) |
503 | link_css_set(&tmp_cg_links, res, dummytop); | |
817929ec PM |
504 | |
505 | BUG_ON(!list_empty(&tmp_cg_links)); | |
506 | ||
817929ec | 507 | css_set_count++; |
472b1053 LZ |
508 | |
509 | /* Add this cgroup group to the hash table */ | |
510 | hhead = css_set_hash(res->subsys); | |
511 | hlist_add_head(&res->hlist, hhead); | |
512 | ||
817929ec PM |
513 | write_unlock(&css_set_lock); |
514 | ||
515 | return res; | |
b4f48b63 PM |
516 | } |
517 | ||
ddbcc7e8 PM |
518 | /* |
519 | * There is one global cgroup mutex. We also require taking | |
520 | * task_lock() when dereferencing a task's cgroup subsys pointers. | |
521 | * See "The task_lock() exception", at the end of this comment. | |
522 | * | |
523 | * A task must hold cgroup_mutex to modify cgroups. | |
524 | * | |
525 | * Any task can increment and decrement the count field without lock. | |
526 | * So in general, code holding cgroup_mutex can't rely on the count | |
527 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 528 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
529 | * means that no tasks are currently attached, therefore there is no |
530 | * way a task attached to that cgroup can fork (the other way to | |
531 | * increment the count). So code holding cgroup_mutex can safely | |
532 | * assume that if the count is zero, it will stay zero. Similarly, if | |
533 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
534 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
535 | * needs that mutex. | |
536 | * | |
ddbcc7e8 PM |
537 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
538 | * (usually) take cgroup_mutex. These are the two most performance | |
539 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
540 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
541 | * is taken, and if the cgroup count is zero, a usermode call made | |
a043e3b2 LZ |
542 | * to the release agent with the name of the cgroup (path relative to |
543 | * the root of cgroup file system) as the argument. | |
ddbcc7e8 PM |
544 | * |
545 | * A cgroup can only be deleted if both its 'count' of using tasks | |
546 | * is zero, and its list of 'children' cgroups is empty. Since all | |
547 | * tasks in the system use _some_ cgroup, and since there is always at | |
548 | * least one task in the system (init, pid == 1), therefore, top_cgroup | |
549 | * always has either children cgroups and/or using tasks. So we don't | |
550 | * need a special hack to ensure that top_cgroup cannot be deleted. | |
551 | * | |
552 | * The task_lock() exception | |
553 | * | |
554 | * The need for this exception arises from the action of | |
956db3ca | 555 | * cgroup_attach_task(), which overwrites one tasks cgroup pointer with |
a043e3b2 | 556 | * another. It does so using cgroup_mutex, however there are |
ddbcc7e8 PM |
557 | * several performance critical places that need to reference |
558 | * task->cgroup without the expense of grabbing a system global | |
559 | * mutex. Therefore except as noted below, when dereferencing or, as | |
956db3ca | 560 | * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use |
ddbcc7e8 PM |
561 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in |
562 | * the task_struct routinely used for such matters. | |
563 | * | |
564 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 565 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
566 | */ |
567 | ||
ddbcc7e8 PM |
568 | /** |
569 | * cgroup_lock - lock out any changes to cgroup structures | |
570 | * | |
571 | */ | |
ddbcc7e8 PM |
572 | void cgroup_lock(void) |
573 | { | |
574 | mutex_lock(&cgroup_mutex); | |
575 | } | |
576 | ||
577 | /** | |
578 | * cgroup_unlock - release lock on cgroup changes | |
579 | * | |
580 | * Undo the lock taken in a previous cgroup_lock() call. | |
581 | */ | |
ddbcc7e8 PM |
582 | void cgroup_unlock(void) |
583 | { | |
584 | mutex_unlock(&cgroup_mutex); | |
585 | } | |
586 | ||
587 | /* | |
588 | * A couple of forward declarations required, due to cyclic reference loop: | |
589 | * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> | |
590 | * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations | |
591 | * -> cgroup_mkdir. | |
592 | */ | |
593 | ||
594 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode); | |
595 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); | |
bd89aabc | 596 | static int cgroup_populate_dir(struct cgroup *cgrp); |
ddbcc7e8 | 597 | static struct inode_operations cgroup_dir_inode_operations; |
a424316c PM |
598 | static struct file_operations proc_cgroupstats_operations; |
599 | ||
600 | static struct backing_dev_info cgroup_backing_dev_info = { | |
e4ad08fe | 601 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
a424316c | 602 | }; |
ddbcc7e8 | 603 | |
38460b48 KH |
604 | static int alloc_css_id(struct cgroup_subsys *ss, |
605 | struct cgroup *parent, struct cgroup *child); | |
606 | ||
ddbcc7e8 PM |
607 | static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb) |
608 | { | |
609 | struct inode *inode = new_inode(sb); | |
ddbcc7e8 PM |
610 | |
611 | if (inode) { | |
612 | inode->i_mode = mode; | |
76aac0e9 DH |
613 | inode->i_uid = current_fsuid(); |
614 | inode->i_gid = current_fsgid(); | |
ddbcc7e8 PM |
615 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
616 | inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; | |
617 | } | |
618 | return inode; | |
619 | } | |
620 | ||
4fca88c8 KH |
621 | /* |
622 | * Call subsys's pre_destroy handler. | |
623 | * This is called before css refcnt check. | |
624 | */ | |
ec64f515 | 625 | static int cgroup_call_pre_destroy(struct cgroup *cgrp) |
4fca88c8 KH |
626 | { |
627 | struct cgroup_subsys *ss; | |
ec64f515 KH |
628 | int ret = 0; |
629 | ||
4fca88c8 | 630 | for_each_subsys(cgrp->root, ss) |
ec64f515 KH |
631 | if (ss->pre_destroy) { |
632 | ret = ss->pre_destroy(ss, cgrp); | |
633 | if (ret) | |
634 | break; | |
635 | } | |
636 | return ret; | |
4fca88c8 KH |
637 | } |
638 | ||
a47295e6 PM |
639 | static void free_cgroup_rcu(struct rcu_head *obj) |
640 | { | |
641 | struct cgroup *cgrp = container_of(obj, struct cgroup, rcu_head); | |
642 | ||
643 | kfree(cgrp); | |
644 | } | |
645 | ||
ddbcc7e8 PM |
646 | static void cgroup_diput(struct dentry *dentry, struct inode *inode) |
647 | { | |
648 | /* is dentry a directory ? if so, kfree() associated cgroup */ | |
649 | if (S_ISDIR(inode->i_mode)) { | |
bd89aabc | 650 | struct cgroup *cgrp = dentry->d_fsdata; |
8dc4f3e1 | 651 | struct cgroup_subsys *ss; |
bd89aabc | 652 | BUG_ON(!(cgroup_is_removed(cgrp))); |
81a6a5cd PM |
653 | /* It's possible for external users to be holding css |
654 | * reference counts on a cgroup; css_put() needs to | |
655 | * be able to access the cgroup after decrementing | |
656 | * the reference count in order to know if it needs to | |
657 | * queue the cgroup to be handled by the release | |
658 | * agent */ | |
659 | synchronize_rcu(); | |
8dc4f3e1 PM |
660 | |
661 | mutex_lock(&cgroup_mutex); | |
662 | /* | |
663 | * Release the subsystem state objects. | |
664 | */ | |
75139b82 LZ |
665 | for_each_subsys(cgrp->root, ss) |
666 | ss->destroy(ss, cgrp); | |
8dc4f3e1 PM |
667 | |
668 | cgrp->root->number_of_cgroups--; | |
669 | mutex_unlock(&cgroup_mutex); | |
670 | ||
a47295e6 PM |
671 | /* |
672 | * Drop the active superblock reference that we took when we | |
673 | * created the cgroup | |
674 | */ | |
8dc4f3e1 PM |
675 | deactivate_super(cgrp->root->sb); |
676 | ||
a47295e6 | 677 | call_rcu(&cgrp->rcu_head, free_cgroup_rcu); |
ddbcc7e8 PM |
678 | } |
679 | iput(inode); | |
680 | } | |
681 | ||
682 | static void remove_dir(struct dentry *d) | |
683 | { | |
684 | struct dentry *parent = dget(d->d_parent); | |
685 | ||
686 | d_delete(d); | |
687 | simple_rmdir(parent->d_inode, d); | |
688 | dput(parent); | |
689 | } | |
690 | ||
691 | static void cgroup_clear_directory(struct dentry *dentry) | |
692 | { | |
693 | struct list_head *node; | |
694 | ||
695 | BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); | |
696 | spin_lock(&dcache_lock); | |
697 | node = dentry->d_subdirs.next; | |
698 | while (node != &dentry->d_subdirs) { | |
699 | struct dentry *d = list_entry(node, struct dentry, d_u.d_child); | |
700 | list_del_init(node); | |
701 | if (d->d_inode) { | |
702 | /* This should never be called on a cgroup | |
703 | * directory with child cgroups */ | |
704 | BUG_ON(d->d_inode->i_mode & S_IFDIR); | |
705 | d = dget_locked(d); | |
706 | spin_unlock(&dcache_lock); | |
707 | d_delete(d); | |
708 | simple_unlink(dentry->d_inode, d); | |
709 | dput(d); | |
710 | spin_lock(&dcache_lock); | |
711 | } | |
712 | node = dentry->d_subdirs.next; | |
713 | } | |
714 | spin_unlock(&dcache_lock); | |
715 | } | |
716 | ||
717 | /* | |
718 | * NOTE : the dentry must have been dget()'ed | |
719 | */ | |
720 | static void cgroup_d_remove_dir(struct dentry *dentry) | |
721 | { | |
722 | cgroup_clear_directory(dentry); | |
723 | ||
724 | spin_lock(&dcache_lock); | |
725 | list_del_init(&dentry->d_u.d_child); | |
726 | spin_unlock(&dcache_lock); | |
727 | remove_dir(dentry); | |
728 | } | |
729 | ||
ec64f515 KH |
730 | /* |
731 | * A queue for waiters to do rmdir() cgroup. A tasks will sleep when | |
732 | * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some | |
733 | * reference to css->refcnt. In general, this refcnt is expected to goes down | |
734 | * to zero, soon. | |
735 | * | |
736 | * CGRP_WAIT_ON_RMDIR flag is modified under cgroup's inode->i_mutex; | |
737 | */ | |
738 | DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq); | |
739 | ||
740 | static void cgroup_wakeup_rmdir_waiters(const struct cgroup *cgrp) | |
741 | { | |
742 | if (unlikely(test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags))) | |
743 | wake_up_all(&cgroup_rmdir_waitq); | |
744 | } | |
745 | ||
ddbcc7e8 PM |
746 | static int rebind_subsystems(struct cgroupfs_root *root, |
747 | unsigned long final_bits) | |
748 | { | |
749 | unsigned long added_bits, removed_bits; | |
bd89aabc | 750 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
751 | int i; |
752 | ||
753 | removed_bits = root->actual_subsys_bits & ~final_bits; | |
754 | added_bits = final_bits & ~root->actual_subsys_bits; | |
755 | /* Check that any added subsystems are currently free */ | |
756 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
8d53d55d | 757 | unsigned long bit = 1UL << i; |
ddbcc7e8 PM |
758 | struct cgroup_subsys *ss = subsys[i]; |
759 | if (!(bit & added_bits)) | |
760 | continue; | |
761 | if (ss->root != &rootnode) { | |
762 | /* Subsystem isn't free */ | |
763 | return -EBUSY; | |
764 | } | |
765 | } | |
766 | ||
767 | /* Currently we don't handle adding/removing subsystems when | |
768 | * any child cgroups exist. This is theoretically supportable | |
769 | * but involves complex error handling, so it's being left until | |
770 | * later */ | |
307257cf | 771 | if (root->number_of_cgroups > 1) |
ddbcc7e8 PM |
772 | return -EBUSY; |
773 | ||
774 | /* Process each subsystem */ | |
775 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
776 | struct cgroup_subsys *ss = subsys[i]; | |
777 | unsigned long bit = 1UL << i; | |
778 | if (bit & added_bits) { | |
779 | /* We're binding this subsystem to this hierarchy */ | |
bd89aabc | 780 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
781 | BUG_ON(!dummytop->subsys[i]); |
782 | BUG_ON(dummytop->subsys[i]->cgroup != dummytop); | |
999cd8a4 | 783 | mutex_lock(&ss->hierarchy_mutex); |
bd89aabc PM |
784 | cgrp->subsys[i] = dummytop->subsys[i]; |
785 | cgrp->subsys[i]->cgroup = cgrp; | |
33a68ac1 | 786 | list_move(&ss->sibling, &root->subsys_list); |
b2aa30f7 | 787 | ss->root = root; |
ddbcc7e8 | 788 | if (ss->bind) |
bd89aabc | 789 | ss->bind(ss, cgrp); |
999cd8a4 | 790 | mutex_unlock(&ss->hierarchy_mutex); |
ddbcc7e8 PM |
791 | } else if (bit & removed_bits) { |
792 | /* We're removing this subsystem */ | |
bd89aabc PM |
793 | BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); |
794 | BUG_ON(cgrp->subsys[i]->cgroup != cgrp); | |
999cd8a4 | 795 | mutex_lock(&ss->hierarchy_mutex); |
ddbcc7e8 PM |
796 | if (ss->bind) |
797 | ss->bind(ss, dummytop); | |
798 | dummytop->subsys[i]->cgroup = dummytop; | |
bd89aabc | 799 | cgrp->subsys[i] = NULL; |
b2aa30f7 | 800 | subsys[i]->root = &rootnode; |
33a68ac1 | 801 | list_move(&ss->sibling, &rootnode.subsys_list); |
999cd8a4 | 802 | mutex_unlock(&ss->hierarchy_mutex); |
ddbcc7e8 PM |
803 | } else if (bit & final_bits) { |
804 | /* Subsystem state should already exist */ | |
bd89aabc | 805 | BUG_ON(!cgrp->subsys[i]); |
ddbcc7e8 PM |
806 | } else { |
807 | /* Subsystem state shouldn't exist */ | |
bd89aabc | 808 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
809 | } |
810 | } | |
811 | root->subsys_bits = root->actual_subsys_bits = final_bits; | |
812 | synchronize_rcu(); | |
813 | ||
814 | return 0; | |
815 | } | |
816 | ||
817 | static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs) | |
818 | { | |
819 | struct cgroupfs_root *root = vfs->mnt_sb->s_fs_info; | |
820 | struct cgroup_subsys *ss; | |
821 | ||
822 | mutex_lock(&cgroup_mutex); | |
823 | for_each_subsys(root, ss) | |
824 | seq_printf(seq, ",%s", ss->name); | |
825 | if (test_bit(ROOT_NOPREFIX, &root->flags)) | |
826 | seq_puts(seq, ",noprefix"); | |
81a6a5cd PM |
827 | if (strlen(root->release_agent_path)) |
828 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
ddbcc7e8 PM |
829 | mutex_unlock(&cgroup_mutex); |
830 | return 0; | |
831 | } | |
832 | ||
833 | struct cgroup_sb_opts { | |
834 | unsigned long subsys_bits; | |
835 | unsigned long flags; | |
81a6a5cd | 836 | char *release_agent; |
ddbcc7e8 PM |
837 | }; |
838 | ||
839 | /* Convert a hierarchy specifier into a bitmask of subsystems and | |
840 | * flags. */ | |
841 | static int parse_cgroupfs_options(char *data, | |
842 | struct cgroup_sb_opts *opts) | |
843 | { | |
844 | char *token, *o = data ?: "all"; | |
845 | ||
846 | opts->subsys_bits = 0; | |
847 | opts->flags = 0; | |
81a6a5cd | 848 | opts->release_agent = NULL; |
ddbcc7e8 PM |
849 | |
850 | while ((token = strsep(&o, ",")) != NULL) { | |
851 | if (!*token) | |
852 | return -EINVAL; | |
853 | if (!strcmp(token, "all")) { | |
8bab8dde PM |
854 | /* Add all non-disabled subsystems */ |
855 | int i; | |
856 | opts->subsys_bits = 0; | |
857 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
858 | struct cgroup_subsys *ss = subsys[i]; | |
859 | if (!ss->disabled) | |
860 | opts->subsys_bits |= 1ul << i; | |
861 | } | |
ddbcc7e8 PM |
862 | } else if (!strcmp(token, "noprefix")) { |
863 | set_bit(ROOT_NOPREFIX, &opts->flags); | |
81a6a5cd PM |
864 | } else if (!strncmp(token, "release_agent=", 14)) { |
865 | /* Specifying two release agents is forbidden */ | |
866 | if (opts->release_agent) | |
867 | return -EINVAL; | |
868 | opts->release_agent = kzalloc(PATH_MAX, GFP_KERNEL); | |
869 | if (!opts->release_agent) | |
870 | return -ENOMEM; | |
871 | strncpy(opts->release_agent, token + 14, PATH_MAX - 1); | |
872 | opts->release_agent[PATH_MAX - 1] = 0; | |
ddbcc7e8 PM |
873 | } else { |
874 | struct cgroup_subsys *ss; | |
875 | int i; | |
876 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
877 | ss = subsys[i]; | |
878 | if (!strcmp(token, ss->name)) { | |
8bab8dde PM |
879 | if (!ss->disabled) |
880 | set_bit(i, &opts->subsys_bits); | |
ddbcc7e8 PM |
881 | break; |
882 | } | |
883 | } | |
884 | if (i == CGROUP_SUBSYS_COUNT) | |
885 | return -ENOENT; | |
886 | } | |
887 | } | |
888 | ||
889 | /* We can't have an empty hierarchy */ | |
890 | if (!opts->subsys_bits) | |
891 | return -EINVAL; | |
892 | ||
893 | return 0; | |
894 | } | |
895 | ||
896 | static int cgroup_remount(struct super_block *sb, int *flags, char *data) | |
897 | { | |
898 | int ret = 0; | |
899 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 900 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
901 | struct cgroup_sb_opts opts; |
902 | ||
bd89aabc | 903 | mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
904 | mutex_lock(&cgroup_mutex); |
905 | ||
906 | /* See what subsystems are wanted */ | |
907 | ret = parse_cgroupfs_options(data, &opts); | |
908 | if (ret) | |
909 | goto out_unlock; | |
910 | ||
911 | /* Don't allow flags to change at remount */ | |
912 | if (opts.flags != root->flags) { | |
913 | ret = -EINVAL; | |
914 | goto out_unlock; | |
915 | } | |
916 | ||
917 | ret = rebind_subsystems(root, opts.subsys_bits); | |
918 | ||
919 | /* (re)populate subsystem files */ | |
920 | if (!ret) | |
bd89aabc | 921 | cgroup_populate_dir(cgrp); |
ddbcc7e8 | 922 | |
81a6a5cd PM |
923 | if (opts.release_agent) |
924 | strcpy(root->release_agent_path, opts.release_agent); | |
ddbcc7e8 | 925 | out_unlock: |
81a6a5cd PM |
926 | if (opts.release_agent) |
927 | kfree(opts.release_agent); | |
ddbcc7e8 | 928 | mutex_unlock(&cgroup_mutex); |
bd89aabc | 929 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
930 | return ret; |
931 | } | |
932 | ||
933 | static struct super_operations cgroup_ops = { | |
934 | .statfs = simple_statfs, | |
935 | .drop_inode = generic_delete_inode, | |
936 | .show_options = cgroup_show_options, | |
937 | .remount_fs = cgroup_remount, | |
938 | }; | |
939 | ||
cc31edce PM |
940 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
941 | { | |
942 | INIT_LIST_HEAD(&cgrp->sibling); | |
943 | INIT_LIST_HEAD(&cgrp->children); | |
944 | INIT_LIST_HEAD(&cgrp->css_sets); | |
945 | INIT_LIST_HEAD(&cgrp->release_list); | |
946 | init_rwsem(&cgrp->pids_mutex); | |
947 | } | |
ddbcc7e8 PM |
948 | static void init_cgroup_root(struct cgroupfs_root *root) |
949 | { | |
bd89aabc | 950 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
951 | INIT_LIST_HEAD(&root->subsys_list); |
952 | INIT_LIST_HEAD(&root->root_list); | |
953 | root->number_of_cgroups = 1; | |
bd89aabc PM |
954 | cgrp->root = root; |
955 | cgrp->top_cgroup = cgrp; | |
cc31edce | 956 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 PM |
957 | } |
958 | ||
959 | static int cgroup_test_super(struct super_block *sb, void *data) | |
960 | { | |
961 | struct cgroupfs_root *new = data; | |
962 | struct cgroupfs_root *root = sb->s_fs_info; | |
963 | ||
964 | /* First check subsystems */ | |
965 | if (new->subsys_bits != root->subsys_bits) | |
966 | return 0; | |
967 | ||
968 | /* Next check flags */ | |
969 | if (new->flags != root->flags) | |
970 | return 0; | |
971 | ||
972 | return 1; | |
973 | } | |
974 | ||
975 | static int cgroup_set_super(struct super_block *sb, void *data) | |
976 | { | |
977 | int ret; | |
978 | struct cgroupfs_root *root = data; | |
979 | ||
980 | ret = set_anon_super(sb, NULL); | |
981 | if (ret) | |
982 | return ret; | |
983 | ||
984 | sb->s_fs_info = root; | |
985 | root->sb = sb; | |
986 | ||
987 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
988 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
989 | sb->s_magic = CGROUP_SUPER_MAGIC; | |
990 | sb->s_op = &cgroup_ops; | |
991 | ||
992 | return 0; | |
993 | } | |
994 | ||
995 | static int cgroup_get_rootdir(struct super_block *sb) | |
996 | { | |
997 | struct inode *inode = | |
998 | cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); | |
999 | struct dentry *dentry; | |
1000 | ||
1001 | if (!inode) | |
1002 | return -ENOMEM; | |
1003 | ||
ddbcc7e8 PM |
1004 | inode->i_fop = &simple_dir_operations; |
1005 | inode->i_op = &cgroup_dir_inode_operations; | |
1006 | /* directories start off with i_nlink == 2 (for "." entry) */ | |
1007 | inc_nlink(inode); | |
1008 | dentry = d_alloc_root(inode); | |
1009 | if (!dentry) { | |
1010 | iput(inode); | |
1011 | return -ENOMEM; | |
1012 | } | |
1013 | sb->s_root = dentry; | |
1014 | return 0; | |
1015 | } | |
1016 | ||
1017 | static int cgroup_get_sb(struct file_system_type *fs_type, | |
1018 | int flags, const char *unused_dev_name, | |
1019 | void *data, struct vfsmount *mnt) | |
1020 | { | |
1021 | struct cgroup_sb_opts opts; | |
1022 | int ret = 0; | |
1023 | struct super_block *sb; | |
1024 | struct cgroupfs_root *root; | |
28fd5dfc | 1025 | struct list_head tmp_cg_links; |
ddbcc7e8 PM |
1026 | |
1027 | /* First find the desired set of subsystems */ | |
1028 | ret = parse_cgroupfs_options(data, &opts); | |
81a6a5cd PM |
1029 | if (ret) { |
1030 | if (opts.release_agent) | |
1031 | kfree(opts.release_agent); | |
ddbcc7e8 | 1032 | return ret; |
81a6a5cd | 1033 | } |
ddbcc7e8 PM |
1034 | |
1035 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
f7770738 LZ |
1036 | if (!root) { |
1037 | if (opts.release_agent) | |
1038 | kfree(opts.release_agent); | |
ddbcc7e8 | 1039 | return -ENOMEM; |
f7770738 | 1040 | } |
ddbcc7e8 PM |
1041 | |
1042 | init_cgroup_root(root); | |
1043 | root->subsys_bits = opts.subsys_bits; | |
1044 | root->flags = opts.flags; | |
81a6a5cd PM |
1045 | if (opts.release_agent) { |
1046 | strcpy(root->release_agent_path, opts.release_agent); | |
1047 | kfree(opts.release_agent); | |
1048 | } | |
ddbcc7e8 PM |
1049 | |
1050 | sb = sget(fs_type, cgroup_test_super, cgroup_set_super, root); | |
1051 | ||
1052 | if (IS_ERR(sb)) { | |
1053 | kfree(root); | |
1054 | return PTR_ERR(sb); | |
1055 | } | |
1056 | ||
1057 | if (sb->s_fs_info != root) { | |
1058 | /* Reusing an existing superblock */ | |
1059 | BUG_ON(sb->s_root == NULL); | |
1060 | kfree(root); | |
1061 | root = NULL; | |
1062 | } else { | |
1063 | /* New superblock */ | |
c12f65d4 | 1064 | struct cgroup *root_cgrp = &root->top_cgroup; |
817929ec | 1065 | struct inode *inode; |
28fd5dfc | 1066 | int i; |
ddbcc7e8 PM |
1067 | |
1068 | BUG_ON(sb->s_root != NULL); | |
1069 | ||
1070 | ret = cgroup_get_rootdir(sb); | |
1071 | if (ret) | |
1072 | goto drop_new_super; | |
817929ec | 1073 | inode = sb->s_root->d_inode; |
ddbcc7e8 | 1074 | |
817929ec | 1075 | mutex_lock(&inode->i_mutex); |
ddbcc7e8 PM |
1076 | mutex_lock(&cgroup_mutex); |
1077 | ||
817929ec PM |
1078 | /* |
1079 | * We're accessing css_set_count without locking | |
1080 | * css_set_lock here, but that's OK - it can only be | |
1081 | * increased by someone holding cgroup_lock, and | |
1082 | * that's us. The worst that can happen is that we | |
1083 | * have some link structures left over | |
1084 | */ | |
1085 | ret = allocate_cg_links(css_set_count, &tmp_cg_links); | |
1086 | if (ret) { | |
1087 | mutex_unlock(&cgroup_mutex); | |
1088 | mutex_unlock(&inode->i_mutex); | |
1089 | goto drop_new_super; | |
1090 | } | |
1091 | ||
ddbcc7e8 PM |
1092 | ret = rebind_subsystems(root, root->subsys_bits); |
1093 | if (ret == -EBUSY) { | |
1094 | mutex_unlock(&cgroup_mutex); | |
817929ec | 1095 | mutex_unlock(&inode->i_mutex); |
20ca9b3f | 1096 | goto free_cg_links; |
ddbcc7e8 PM |
1097 | } |
1098 | ||
1099 | /* EBUSY should be the only error here */ | |
1100 | BUG_ON(ret); | |
1101 | ||
1102 | list_add(&root->root_list, &roots); | |
817929ec | 1103 | root_count++; |
ddbcc7e8 | 1104 | |
c12f65d4 | 1105 | sb->s_root->d_fsdata = root_cgrp; |
ddbcc7e8 PM |
1106 | root->top_cgroup.dentry = sb->s_root; |
1107 | ||
817929ec PM |
1108 | /* Link the top cgroup in this hierarchy into all |
1109 | * the css_set objects */ | |
1110 | write_lock(&css_set_lock); | |
28fd5dfc LZ |
1111 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { |
1112 | struct hlist_head *hhead = &css_set_table[i]; | |
1113 | struct hlist_node *node; | |
817929ec | 1114 | struct css_set *cg; |
28fd5dfc | 1115 | |
c12f65d4 LZ |
1116 | hlist_for_each_entry(cg, node, hhead, hlist) |
1117 | link_css_set(&tmp_cg_links, cg, root_cgrp); | |
28fd5dfc | 1118 | } |
817929ec PM |
1119 | write_unlock(&css_set_lock); |
1120 | ||
1121 | free_cg_links(&tmp_cg_links); | |
1122 | ||
c12f65d4 LZ |
1123 | BUG_ON(!list_empty(&root_cgrp->sibling)); |
1124 | BUG_ON(!list_empty(&root_cgrp->children)); | |
ddbcc7e8 PM |
1125 | BUG_ON(root->number_of_cgroups != 1); |
1126 | ||
c12f65d4 | 1127 | cgroup_populate_dir(root_cgrp); |
817929ec | 1128 | mutex_unlock(&inode->i_mutex); |
ddbcc7e8 PM |
1129 | mutex_unlock(&cgroup_mutex); |
1130 | } | |
1131 | ||
a3ec947c SB |
1132 | simple_set_mnt(mnt, sb); |
1133 | return 0; | |
ddbcc7e8 | 1134 | |
20ca9b3f LZ |
1135 | free_cg_links: |
1136 | free_cg_links(&tmp_cg_links); | |
ddbcc7e8 PM |
1137 | drop_new_super: |
1138 | up_write(&sb->s_umount); | |
1139 | deactivate_super(sb); | |
1140 | return ret; | |
1141 | } | |
1142 | ||
1143 | static void cgroup_kill_sb(struct super_block *sb) { | |
1144 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1145 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 | 1146 | int ret; |
71cbb949 KM |
1147 | struct cg_cgroup_link *link; |
1148 | struct cg_cgroup_link *saved_link; | |
ddbcc7e8 PM |
1149 | |
1150 | BUG_ON(!root); | |
1151 | ||
1152 | BUG_ON(root->number_of_cgroups != 1); | |
bd89aabc PM |
1153 | BUG_ON(!list_empty(&cgrp->children)); |
1154 | BUG_ON(!list_empty(&cgrp->sibling)); | |
ddbcc7e8 PM |
1155 | |
1156 | mutex_lock(&cgroup_mutex); | |
1157 | ||
1158 | /* Rebind all subsystems back to the default hierarchy */ | |
1159 | ret = rebind_subsystems(root, 0); | |
1160 | /* Shouldn't be able to fail ... */ | |
1161 | BUG_ON(ret); | |
1162 | ||
817929ec PM |
1163 | /* |
1164 | * Release all the links from css_sets to this hierarchy's | |
1165 | * root cgroup | |
1166 | */ | |
1167 | write_lock(&css_set_lock); | |
71cbb949 KM |
1168 | |
1169 | list_for_each_entry_safe(link, saved_link, &cgrp->css_sets, | |
1170 | cgrp_link_list) { | |
817929ec | 1171 | list_del(&link->cg_link_list); |
bd89aabc | 1172 | list_del(&link->cgrp_link_list); |
817929ec PM |
1173 | kfree(link); |
1174 | } | |
1175 | write_unlock(&css_set_lock); | |
1176 | ||
839ec545 PM |
1177 | if (!list_empty(&root->root_list)) { |
1178 | list_del(&root->root_list); | |
1179 | root_count--; | |
1180 | } | |
e5f6a860 | 1181 | |
ddbcc7e8 PM |
1182 | mutex_unlock(&cgroup_mutex); |
1183 | ||
ddbcc7e8 | 1184 | kill_litter_super(sb); |
67e055d1 | 1185 | kfree(root); |
ddbcc7e8 PM |
1186 | } |
1187 | ||
1188 | static struct file_system_type cgroup_fs_type = { | |
1189 | .name = "cgroup", | |
1190 | .get_sb = cgroup_get_sb, | |
1191 | .kill_sb = cgroup_kill_sb, | |
1192 | }; | |
1193 | ||
bd89aabc | 1194 | static inline struct cgroup *__d_cgrp(struct dentry *dentry) |
ddbcc7e8 PM |
1195 | { |
1196 | return dentry->d_fsdata; | |
1197 | } | |
1198 | ||
1199 | static inline struct cftype *__d_cft(struct dentry *dentry) | |
1200 | { | |
1201 | return dentry->d_fsdata; | |
1202 | } | |
1203 | ||
a043e3b2 LZ |
1204 | /** |
1205 | * cgroup_path - generate the path of a cgroup | |
1206 | * @cgrp: the cgroup in question | |
1207 | * @buf: the buffer to write the path into | |
1208 | * @buflen: the length of the buffer | |
1209 | * | |
a47295e6 PM |
1210 | * Called with cgroup_mutex held or else with an RCU-protected cgroup |
1211 | * reference. Writes path of cgroup into buf. Returns 0 on success, | |
1212 | * -errno on error. | |
ddbcc7e8 | 1213 | */ |
bd89aabc | 1214 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) |
ddbcc7e8 PM |
1215 | { |
1216 | char *start; | |
a47295e6 | 1217 | struct dentry *dentry = rcu_dereference(cgrp->dentry); |
ddbcc7e8 | 1218 | |
a47295e6 | 1219 | if (!dentry || cgrp == dummytop) { |
ddbcc7e8 PM |
1220 | /* |
1221 | * Inactive subsystems have no dentry for their root | |
1222 | * cgroup | |
1223 | */ | |
1224 | strcpy(buf, "/"); | |
1225 | return 0; | |
1226 | } | |
1227 | ||
1228 | start = buf + buflen; | |
1229 | ||
1230 | *--start = '\0'; | |
1231 | for (;;) { | |
a47295e6 | 1232 | int len = dentry->d_name.len; |
ddbcc7e8 PM |
1233 | if ((start -= len) < buf) |
1234 | return -ENAMETOOLONG; | |
bd89aabc PM |
1235 | memcpy(start, cgrp->dentry->d_name.name, len); |
1236 | cgrp = cgrp->parent; | |
1237 | if (!cgrp) | |
ddbcc7e8 | 1238 | break; |
a47295e6 | 1239 | dentry = rcu_dereference(cgrp->dentry); |
bd89aabc | 1240 | if (!cgrp->parent) |
ddbcc7e8 PM |
1241 | continue; |
1242 | if (--start < buf) | |
1243 | return -ENAMETOOLONG; | |
1244 | *start = '/'; | |
1245 | } | |
1246 | memmove(buf, start, buf + buflen - start); | |
1247 | return 0; | |
1248 | } | |
1249 | ||
bbcb81d0 PM |
1250 | /* |
1251 | * Return the first subsystem attached to a cgroup's hierarchy, and | |
1252 | * its subsystem id. | |
1253 | */ | |
1254 | ||
bd89aabc | 1255 | static void get_first_subsys(const struct cgroup *cgrp, |
bbcb81d0 PM |
1256 | struct cgroup_subsys_state **css, int *subsys_id) |
1257 | { | |
bd89aabc | 1258 | const struct cgroupfs_root *root = cgrp->root; |
bbcb81d0 PM |
1259 | const struct cgroup_subsys *test_ss; |
1260 | BUG_ON(list_empty(&root->subsys_list)); | |
1261 | test_ss = list_entry(root->subsys_list.next, | |
1262 | struct cgroup_subsys, sibling); | |
1263 | if (css) { | |
bd89aabc | 1264 | *css = cgrp->subsys[test_ss->subsys_id]; |
bbcb81d0 PM |
1265 | BUG_ON(!*css); |
1266 | } | |
1267 | if (subsys_id) | |
1268 | *subsys_id = test_ss->subsys_id; | |
1269 | } | |
1270 | ||
a043e3b2 LZ |
1271 | /** |
1272 | * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' | |
1273 | * @cgrp: the cgroup the task is attaching to | |
1274 | * @tsk: the task to be attached | |
bbcb81d0 | 1275 | * |
a043e3b2 LZ |
1276 | * Call holding cgroup_mutex. May take task_lock of |
1277 | * the task 'tsk' during call. | |
bbcb81d0 | 1278 | */ |
956db3ca | 1279 | int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) |
bbcb81d0 PM |
1280 | { |
1281 | int retval = 0; | |
1282 | struct cgroup_subsys *ss; | |
bd89aabc | 1283 | struct cgroup *oldcgrp; |
77efecd9 | 1284 | struct css_set *cg; |
817929ec | 1285 | struct css_set *newcg; |
bd89aabc | 1286 | struct cgroupfs_root *root = cgrp->root; |
bbcb81d0 PM |
1287 | int subsys_id; |
1288 | ||
bd89aabc | 1289 | get_first_subsys(cgrp, NULL, &subsys_id); |
bbcb81d0 PM |
1290 | |
1291 | /* Nothing to do if the task is already in that cgroup */ | |
bd89aabc PM |
1292 | oldcgrp = task_cgroup(tsk, subsys_id); |
1293 | if (cgrp == oldcgrp) | |
bbcb81d0 PM |
1294 | return 0; |
1295 | ||
1296 | for_each_subsys(root, ss) { | |
1297 | if (ss->can_attach) { | |
bd89aabc | 1298 | retval = ss->can_attach(ss, cgrp, tsk); |
e18f6318 | 1299 | if (retval) |
bbcb81d0 | 1300 | return retval; |
bbcb81d0 PM |
1301 | } |
1302 | } | |
1303 | ||
77efecd9 LJ |
1304 | task_lock(tsk); |
1305 | cg = tsk->cgroups; | |
1306 | get_css_set(cg); | |
1307 | task_unlock(tsk); | |
817929ec PM |
1308 | /* |
1309 | * Locate or allocate a new css_set for this task, | |
1310 | * based on its final set of cgroups | |
1311 | */ | |
bd89aabc | 1312 | newcg = find_css_set(cg, cgrp); |
77efecd9 | 1313 | put_css_set(cg); |
e18f6318 | 1314 | if (!newcg) |
817929ec | 1315 | return -ENOMEM; |
817929ec | 1316 | |
bbcb81d0 PM |
1317 | task_lock(tsk); |
1318 | if (tsk->flags & PF_EXITING) { | |
1319 | task_unlock(tsk); | |
817929ec | 1320 | put_css_set(newcg); |
bbcb81d0 PM |
1321 | return -ESRCH; |
1322 | } | |
817929ec | 1323 | rcu_assign_pointer(tsk->cgroups, newcg); |
bbcb81d0 PM |
1324 | task_unlock(tsk); |
1325 | ||
817929ec PM |
1326 | /* Update the css_set linked lists if we're using them */ |
1327 | write_lock(&css_set_lock); | |
1328 | if (!list_empty(&tsk->cg_list)) { | |
1329 | list_del(&tsk->cg_list); | |
1330 | list_add(&tsk->cg_list, &newcg->tasks); | |
1331 | } | |
1332 | write_unlock(&css_set_lock); | |
1333 | ||
bbcb81d0 | 1334 | for_each_subsys(root, ss) { |
e18f6318 | 1335 | if (ss->attach) |
bd89aabc | 1336 | ss->attach(ss, cgrp, oldcgrp, tsk); |
bbcb81d0 | 1337 | } |
bd89aabc | 1338 | set_bit(CGRP_RELEASABLE, &oldcgrp->flags); |
bbcb81d0 | 1339 | synchronize_rcu(); |
817929ec | 1340 | put_css_set(cg); |
ec64f515 KH |
1341 | |
1342 | /* | |
1343 | * wake up rmdir() waiter. the rmdir should fail since the cgroup | |
1344 | * is no longer empty. | |
1345 | */ | |
1346 | cgroup_wakeup_rmdir_waiters(cgrp); | |
bbcb81d0 PM |
1347 | return 0; |
1348 | } | |
1349 | ||
1350 | /* | |
af351026 PM |
1351 | * Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex |
1352 | * held. May take task_lock of task | |
bbcb81d0 | 1353 | */ |
af351026 | 1354 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid) |
bbcb81d0 | 1355 | { |
bbcb81d0 | 1356 | struct task_struct *tsk; |
c69e8d9c | 1357 | const struct cred *cred = current_cred(), *tcred; |
bbcb81d0 PM |
1358 | int ret; |
1359 | ||
bbcb81d0 PM |
1360 | if (pid) { |
1361 | rcu_read_lock(); | |
73507f33 | 1362 | tsk = find_task_by_vpid(pid); |
bbcb81d0 PM |
1363 | if (!tsk || tsk->flags & PF_EXITING) { |
1364 | rcu_read_unlock(); | |
1365 | return -ESRCH; | |
1366 | } | |
bbcb81d0 | 1367 | |
c69e8d9c DH |
1368 | tcred = __task_cred(tsk); |
1369 | if (cred->euid && | |
1370 | cred->euid != tcred->uid && | |
1371 | cred->euid != tcred->suid) { | |
1372 | rcu_read_unlock(); | |
bbcb81d0 PM |
1373 | return -EACCES; |
1374 | } | |
c69e8d9c DH |
1375 | get_task_struct(tsk); |
1376 | rcu_read_unlock(); | |
bbcb81d0 PM |
1377 | } else { |
1378 | tsk = current; | |
1379 | get_task_struct(tsk); | |
1380 | } | |
1381 | ||
956db3ca | 1382 | ret = cgroup_attach_task(cgrp, tsk); |
bbcb81d0 PM |
1383 | put_task_struct(tsk); |
1384 | return ret; | |
1385 | } | |
1386 | ||
af351026 PM |
1387 | static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) |
1388 | { | |
1389 | int ret; | |
1390 | if (!cgroup_lock_live_group(cgrp)) | |
1391 | return -ENODEV; | |
1392 | ret = attach_task_by_pid(cgrp, pid); | |
1393 | cgroup_unlock(); | |
1394 | return ret; | |
1395 | } | |
1396 | ||
ddbcc7e8 | 1397 | /* The various types of files and directories in a cgroup file system */ |
ddbcc7e8 PM |
1398 | enum cgroup_filetype { |
1399 | FILE_ROOT, | |
1400 | FILE_DIR, | |
1401 | FILE_TASKLIST, | |
81a6a5cd | 1402 | FILE_NOTIFY_ON_RELEASE, |
81a6a5cd | 1403 | FILE_RELEASE_AGENT, |
ddbcc7e8 PM |
1404 | }; |
1405 | ||
e788e066 PM |
1406 | /** |
1407 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
1408 | * @cgrp: the cgroup to be checked for liveness | |
1409 | * | |
84eea842 PM |
1410 | * On success, returns true; the lock should be later released with |
1411 | * cgroup_unlock(). On failure returns false with no lock held. | |
e788e066 | 1412 | */ |
84eea842 | 1413 | bool cgroup_lock_live_group(struct cgroup *cgrp) |
e788e066 PM |
1414 | { |
1415 | mutex_lock(&cgroup_mutex); | |
1416 | if (cgroup_is_removed(cgrp)) { | |
1417 | mutex_unlock(&cgroup_mutex); | |
1418 | return false; | |
1419 | } | |
1420 | return true; | |
1421 | } | |
1422 | ||
1423 | static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, | |
1424 | const char *buffer) | |
1425 | { | |
1426 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); | |
1427 | if (!cgroup_lock_live_group(cgrp)) | |
1428 | return -ENODEV; | |
1429 | strcpy(cgrp->root->release_agent_path, buffer); | |
84eea842 | 1430 | cgroup_unlock(); |
e788e066 PM |
1431 | return 0; |
1432 | } | |
1433 | ||
1434 | static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, | |
1435 | struct seq_file *seq) | |
1436 | { | |
1437 | if (!cgroup_lock_live_group(cgrp)) | |
1438 | return -ENODEV; | |
1439 | seq_puts(seq, cgrp->root->release_agent_path); | |
1440 | seq_putc(seq, '\n'); | |
84eea842 | 1441 | cgroup_unlock(); |
e788e066 PM |
1442 | return 0; |
1443 | } | |
1444 | ||
84eea842 PM |
1445 | /* A buffer size big enough for numbers or short strings */ |
1446 | #define CGROUP_LOCAL_BUFFER_SIZE 64 | |
1447 | ||
e73d2c61 | 1448 | static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, |
f4c753b7 PM |
1449 | struct file *file, |
1450 | const char __user *userbuf, | |
1451 | size_t nbytes, loff_t *unused_ppos) | |
355e0c48 | 1452 | { |
84eea842 | 1453 | char buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
355e0c48 | 1454 | int retval = 0; |
355e0c48 PM |
1455 | char *end; |
1456 | ||
1457 | if (!nbytes) | |
1458 | return -EINVAL; | |
1459 | if (nbytes >= sizeof(buffer)) | |
1460 | return -E2BIG; | |
1461 | if (copy_from_user(buffer, userbuf, nbytes)) | |
1462 | return -EFAULT; | |
1463 | ||
1464 | buffer[nbytes] = 0; /* nul-terminate */ | |
b7269dfc | 1465 | strstrip(buffer); |
e73d2c61 PM |
1466 | if (cft->write_u64) { |
1467 | u64 val = simple_strtoull(buffer, &end, 0); | |
1468 | if (*end) | |
1469 | return -EINVAL; | |
1470 | retval = cft->write_u64(cgrp, cft, val); | |
1471 | } else { | |
1472 | s64 val = simple_strtoll(buffer, &end, 0); | |
1473 | if (*end) | |
1474 | return -EINVAL; | |
1475 | retval = cft->write_s64(cgrp, cft, val); | |
1476 | } | |
355e0c48 PM |
1477 | if (!retval) |
1478 | retval = nbytes; | |
1479 | return retval; | |
1480 | } | |
1481 | ||
db3b1497 PM |
1482 | static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, |
1483 | struct file *file, | |
1484 | const char __user *userbuf, | |
1485 | size_t nbytes, loff_t *unused_ppos) | |
1486 | { | |
84eea842 | 1487 | char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
db3b1497 PM |
1488 | int retval = 0; |
1489 | size_t max_bytes = cft->max_write_len; | |
1490 | char *buffer = local_buffer; | |
1491 | ||
1492 | if (!max_bytes) | |
1493 | max_bytes = sizeof(local_buffer) - 1; | |
1494 | if (nbytes >= max_bytes) | |
1495 | return -E2BIG; | |
1496 | /* Allocate a dynamic buffer if we need one */ | |
1497 | if (nbytes >= sizeof(local_buffer)) { | |
1498 | buffer = kmalloc(nbytes + 1, GFP_KERNEL); | |
1499 | if (buffer == NULL) | |
1500 | return -ENOMEM; | |
1501 | } | |
5a3eb9f6 LZ |
1502 | if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { |
1503 | retval = -EFAULT; | |
1504 | goto out; | |
1505 | } | |
db3b1497 PM |
1506 | |
1507 | buffer[nbytes] = 0; /* nul-terminate */ | |
1508 | strstrip(buffer); | |
1509 | retval = cft->write_string(cgrp, cft, buffer); | |
1510 | if (!retval) | |
1511 | retval = nbytes; | |
5a3eb9f6 | 1512 | out: |
db3b1497 PM |
1513 | if (buffer != local_buffer) |
1514 | kfree(buffer); | |
1515 | return retval; | |
1516 | } | |
1517 | ||
ddbcc7e8 PM |
1518 | static ssize_t cgroup_file_write(struct file *file, const char __user *buf, |
1519 | size_t nbytes, loff_t *ppos) | |
1520 | { | |
1521 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 1522 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 1523 | |
75139b82 | 1524 | if (cgroup_is_removed(cgrp)) |
ddbcc7e8 | 1525 | return -ENODEV; |
355e0c48 | 1526 | if (cft->write) |
bd89aabc | 1527 | return cft->write(cgrp, cft, file, buf, nbytes, ppos); |
e73d2c61 PM |
1528 | if (cft->write_u64 || cft->write_s64) |
1529 | return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); | |
db3b1497 PM |
1530 | if (cft->write_string) |
1531 | return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); | |
d447ea2f PE |
1532 | if (cft->trigger) { |
1533 | int ret = cft->trigger(cgrp, (unsigned int)cft->private); | |
1534 | return ret ? ret : nbytes; | |
1535 | } | |
355e0c48 | 1536 | return -EINVAL; |
ddbcc7e8 PM |
1537 | } |
1538 | ||
f4c753b7 PM |
1539 | static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, |
1540 | struct file *file, | |
1541 | char __user *buf, size_t nbytes, | |
1542 | loff_t *ppos) | |
ddbcc7e8 | 1543 | { |
84eea842 | 1544 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
f4c753b7 | 1545 | u64 val = cft->read_u64(cgrp, cft); |
ddbcc7e8 PM |
1546 | int len = sprintf(tmp, "%llu\n", (unsigned long long) val); |
1547 | ||
1548 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
1549 | } | |
1550 | ||
e73d2c61 PM |
1551 | static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft, |
1552 | struct file *file, | |
1553 | char __user *buf, size_t nbytes, | |
1554 | loff_t *ppos) | |
1555 | { | |
84eea842 | 1556 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
e73d2c61 PM |
1557 | s64 val = cft->read_s64(cgrp, cft); |
1558 | int len = sprintf(tmp, "%lld\n", (long long) val); | |
1559 | ||
1560 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
1561 | } | |
1562 | ||
ddbcc7e8 PM |
1563 | static ssize_t cgroup_file_read(struct file *file, char __user *buf, |
1564 | size_t nbytes, loff_t *ppos) | |
1565 | { | |
1566 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 1567 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 1568 | |
75139b82 | 1569 | if (cgroup_is_removed(cgrp)) |
ddbcc7e8 PM |
1570 | return -ENODEV; |
1571 | ||
1572 | if (cft->read) | |
bd89aabc | 1573 | return cft->read(cgrp, cft, file, buf, nbytes, ppos); |
f4c753b7 PM |
1574 | if (cft->read_u64) |
1575 | return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos); | |
e73d2c61 PM |
1576 | if (cft->read_s64) |
1577 | return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos); | |
ddbcc7e8 PM |
1578 | return -EINVAL; |
1579 | } | |
1580 | ||
91796569 PM |
1581 | /* |
1582 | * seqfile ops/methods for returning structured data. Currently just | |
1583 | * supports string->u64 maps, but can be extended in future. | |
1584 | */ | |
1585 | ||
1586 | struct cgroup_seqfile_state { | |
1587 | struct cftype *cft; | |
1588 | struct cgroup *cgroup; | |
1589 | }; | |
1590 | ||
1591 | static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) | |
1592 | { | |
1593 | struct seq_file *sf = cb->state; | |
1594 | return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); | |
1595 | } | |
1596 | ||
1597 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) | |
1598 | { | |
1599 | struct cgroup_seqfile_state *state = m->private; | |
1600 | struct cftype *cft = state->cft; | |
29486df3 SH |
1601 | if (cft->read_map) { |
1602 | struct cgroup_map_cb cb = { | |
1603 | .fill = cgroup_map_add, | |
1604 | .state = m, | |
1605 | }; | |
1606 | return cft->read_map(state->cgroup, cft, &cb); | |
1607 | } | |
1608 | return cft->read_seq_string(state->cgroup, cft, m); | |
91796569 PM |
1609 | } |
1610 | ||
96930a63 | 1611 | static int cgroup_seqfile_release(struct inode *inode, struct file *file) |
91796569 PM |
1612 | { |
1613 | struct seq_file *seq = file->private_data; | |
1614 | kfree(seq->private); | |
1615 | return single_release(inode, file); | |
1616 | } | |
1617 | ||
1618 | static struct file_operations cgroup_seqfile_operations = { | |
1619 | .read = seq_read, | |
e788e066 | 1620 | .write = cgroup_file_write, |
91796569 PM |
1621 | .llseek = seq_lseek, |
1622 | .release = cgroup_seqfile_release, | |
1623 | }; | |
1624 | ||
ddbcc7e8 PM |
1625 | static int cgroup_file_open(struct inode *inode, struct file *file) |
1626 | { | |
1627 | int err; | |
1628 | struct cftype *cft; | |
1629 | ||
1630 | err = generic_file_open(inode, file); | |
1631 | if (err) | |
1632 | return err; | |
ddbcc7e8 | 1633 | cft = __d_cft(file->f_dentry); |
75139b82 | 1634 | |
29486df3 | 1635 | if (cft->read_map || cft->read_seq_string) { |
91796569 PM |
1636 | struct cgroup_seqfile_state *state = |
1637 | kzalloc(sizeof(*state), GFP_USER); | |
1638 | if (!state) | |
1639 | return -ENOMEM; | |
1640 | state->cft = cft; | |
1641 | state->cgroup = __d_cgrp(file->f_dentry->d_parent); | |
1642 | file->f_op = &cgroup_seqfile_operations; | |
1643 | err = single_open(file, cgroup_seqfile_show, state); | |
1644 | if (err < 0) | |
1645 | kfree(state); | |
1646 | } else if (cft->open) | |
ddbcc7e8 PM |
1647 | err = cft->open(inode, file); |
1648 | else | |
1649 | err = 0; | |
1650 | ||
1651 | return err; | |
1652 | } | |
1653 | ||
1654 | static int cgroup_file_release(struct inode *inode, struct file *file) | |
1655 | { | |
1656 | struct cftype *cft = __d_cft(file->f_dentry); | |
1657 | if (cft->release) | |
1658 | return cft->release(inode, file); | |
1659 | return 0; | |
1660 | } | |
1661 | ||
1662 | /* | |
1663 | * cgroup_rename - Only allow simple rename of directories in place. | |
1664 | */ | |
1665 | static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, | |
1666 | struct inode *new_dir, struct dentry *new_dentry) | |
1667 | { | |
1668 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) | |
1669 | return -ENOTDIR; | |
1670 | if (new_dentry->d_inode) | |
1671 | return -EEXIST; | |
1672 | if (old_dir != new_dir) | |
1673 | return -EIO; | |
1674 | return simple_rename(old_dir, old_dentry, new_dir, new_dentry); | |
1675 | } | |
1676 | ||
1677 | static struct file_operations cgroup_file_operations = { | |
1678 | .read = cgroup_file_read, | |
1679 | .write = cgroup_file_write, | |
1680 | .llseek = generic_file_llseek, | |
1681 | .open = cgroup_file_open, | |
1682 | .release = cgroup_file_release, | |
1683 | }; | |
1684 | ||
1685 | static struct inode_operations cgroup_dir_inode_operations = { | |
1686 | .lookup = simple_lookup, | |
1687 | .mkdir = cgroup_mkdir, | |
1688 | .rmdir = cgroup_rmdir, | |
1689 | .rename = cgroup_rename, | |
1690 | }; | |
1691 | ||
1692 | static int cgroup_create_file(struct dentry *dentry, int mode, | |
1693 | struct super_block *sb) | |
1694 | { | |
3ba13d17 | 1695 | static const struct dentry_operations cgroup_dops = { |
ddbcc7e8 PM |
1696 | .d_iput = cgroup_diput, |
1697 | }; | |
1698 | ||
1699 | struct inode *inode; | |
1700 | ||
1701 | if (!dentry) | |
1702 | return -ENOENT; | |
1703 | if (dentry->d_inode) | |
1704 | return -EEXIST; | |
1705 | ||
1706 | inode = cgroup_new_inode(mode, sb); | |
1707 | if (!inode) | |
1708 | return -ENOMEM; | |
1709 | ||
1710 | if (S_ISDIR(mode)) { | |
1711 | inode->i_op = &cgroup_dir_inode_operations; | |
1712 | inode->i_fop = &simple_dir_operations; | |
1713 | ||
1714 | /* start off with i_nlink == 2 (for "." entry) */ | |
1715 | inc_nlink(inode); | |
1716 | ||
1717 | /* start with the directory inode held, so that we can | |
1718 | * populate it without racing with another mkdir */ | |
817929ec | 1719 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); |
ddbcc7e8 PM |
1720 | } else if (S_ISREG(mode)) { |
1721 | inode->i_size = 0; | |
1722 | inode->i_fop = &cgroup_file_operations; | |
1723 | } | |
1724 | dentry->d_op = &cgroup_dops; | |
1725 | d_instantiate(dentry, inode); | |
1726 | dget(dentry); /* Extra count - pin the dentry in core */ | |
1727 | return 0; | |
1728 | } | |
1729 | ||
1730 | /* | |
a043e3b2 LZ |
1731 | * cgroup_create_dir - create a directory for an object. |
1732 | * @cgrp: the cgroup we create the directory for. It must have a valid | |
1733 | * ->parent field. And we are going to fill its ->dentry field. | |
1734 | * @dentry: dentry of the new cgroup | |
1735 | * @mode: mode to set on new directory. | |
ddbcc7e8 | 1736 | */ |
bd89aabc | 1737 | static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry, |
ddbcc7e8 PM |
1738 | int mode) |
1739 | { | |
1740 | struct dentry *parent; | |
1741 | int error = 0; | |
1742 | ||
bd89aabc PM |
1743 | parent = cgrp->parent->dentry; |
1744 | error = cgroup_create_file(dentry, S_IFDIR | mode, cgrp->root->sb); | |
ddbcc7e8 | 1745 | if (!error) { |
bd89aabc | 1746 | dentry->d_fsdata = cgrp; |
ddbcc7e8 | 1747 | inc_nlink(parent->d_inode); |
a47295e6 | 1748 | rcu_assign_pointer(cgrp->dentry, dentry); |
ddbcc7e8 PM |
1749 | dget(dentry); |
1750 | } | |
1751 | dput(dentry); | |
1752 | ||
1753 | return error; | |
1754 | } | |
1755 | ||
bd89aabc | 1756 | int cgroup_add_file(struct cgroup *cgrp, |
ddbcc7e8 PM |
1757 | struct cgroup_subsys *subsys, |
1758 | const struct cftype *cft) | |
1759 | { | |
bd89aabc | 1760 | struct dentry *dir = cgrp->dentry; |
ddbcc7e8 PM |
1761 | struct dentry *dentry; |
1762 | int error; | |
1763 | ||
1764 | char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; | |
bd89aabc | 1765 | if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) { |
ddbcc7e8 PM |
1766 | strcpy(name, subsys->name); |
1767 | strcat(name, "."); | |
1768 | } | |
1769 | strcat(name, cft->name); | |
1770 | BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); | |
1771 | dentry = lookup_one_len(name, dir, strlen(name)); | |
1772 | if (!IS_ERR(dentry)) { | |
1773 | error = cgroup_create_file(dentry, 0644 | S_IFREG, | |
bd89aabc | 1774 | cgrp->root->sb); |
ddbcc7e8 PM |
1775 | if (!error) |
1776 | dentry->d_fsdata = (void *)cft; | |
1777 | dput(dentry); | |
1778 | } else | |
1779 | error = PTR_ERR(dentry); | |
1780 | return error; | |
1781 | } | |
1782 | ||
bd89aabc | 1783 | int cgroup_add_files(struct cgroup *cgrp, |
ddbcc7e8 PM |
1784 | struct cgroup_subsys *subsys, |
1785 | const struct cftype cft[], | |
1786 | int count) | |
1787 | { | |
1788 | int i, err; | |
1789 | for (i = 0; i < count; i++) { | |
bd89aabc | 1790 | err = cgroup_add_file(cgrp, subsys, &cft[i]); |
ddbcc7e8 PM |
1791 | if (err) |
1792 | return err; | |
1793 | } | |
1794 | return 0; | |
1795 | } | |
1796 | ||
a043e3b2 LZ |
1797 | /** |
1798 | * cgroup_task_count - count the number of tasks in a cgroup. | |
1799 | * @cgrp: the cgroup in question | |
1800 | * | |
1801 | * Return the number of tasks in the cgroup. | |
1802 | */ | |
bd89aabc | 1803 | int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
1804 | { |
1805 | int count = 0; | |
71cbb949 | 1806 | struct cg_cgroup_link *link; |
817929ec PM |
1807 | |
1808 | read_lock(&css_set_lock); | |
71cbb949 | 1809 | list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) { |
146aa1bd | 1810 | count += atomic_read(&link->cg->refcount); |
817929ec PM |
1811 | } |
1812 | read_unlock(&css_set_lock); | |
bbcb81d0 PM |
1813 | return count; |
1814 | } | |
1815 | ||
817929ec PM |
1816 | /* |
1817 | * Advance a list_head iterator. The iterator should be positioned at | |
1818 | * the start of a css_set | |
1819 | */ | |
bd89aabc | 1820 | static void cgroup_advance_iter(struct cgroup *cgrp, |
817929ec PM |
1821 | struct cgroup_iter *it) |
1822 | { | |
1823 | struct list_head *l = it->cg_link; | |
1824 | struct cg_cgroup_link *link; | |
1825 | struct css_set *cg; | |
1826 | ||
1827 | /* Advance to the next non-empty css_set */ | |
1828 | do { | |
1829 | l = l->next; | |
bd89aabc | 1830 | if (l == &cgrp->css_sets) { |
817929ec PM |
1831 | it->cg_link = NULL; |
1832 | return; | |
1833 | } | |
bd89aabc | 1834 | link = list_entry(l, struct cg_cgroup_link, cgrp_link_list); |
817929ec PM |
1835 | cg = link->cg; |
1836 | } while (list_empty(&cg->tasks)); | |
1837 | it->cg_link = l; | |
1838 | it->task = cg->tasks.next; | |
1839 | } | |
1840 | ||
31a7df01 CW |
1841 | /* |
1842 | * To reduce the fork() overhead for systems that are not actually | |
1843 | * using their cgroups capability, we don't maintain the lists running | |
1844 | * through each css_set to its tasks until we see the list actually | |
1845 | * used - in other words after the first call to cgroup_iter_start(). | |
1846 | * | |
1847 | * The tasklist_lock is not held here, as do_each_thread() and | |
1848 | * while_each_thread() are protected by RCU. | |
1849 | */ | |
3df91fe3 | 1850 | static void cgroup_enable_task_cg_lists(void) |
31a7df01 CW |
1851 | { |
1852 | struct task_struct *p, *g; | |
1853 | write_lock(&css_set_lock); | |
1854 | use_task_css_set_links = 1; | |
1855 | do_each_thread(g, p) { | |
1856 | task_lock(p); | |
0e04388f LZ |
1857 | /* |
1858 | * We should check if the process is exiting, otherwise | |
1859 | * it will race with cgroup_exit() in that the list | |
1860 | * entry won't be deleted though the process has exited. | |
1861 | */ | |
1862 | if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) | |
31a7df01 CW |
1863 | list_add(&p->cg_list, &p->cgroups->tasks); |
1864 | task_unlock(p); | |
1865 | } while_each_thread(g, p); | |
1866 | write_unlock(&css_set_lock); | |
1867 | } | |
1868 | ||
bd89aabc | 1869 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) |
817929ec PM |
1870 | { |
1871 | /* | |
1872 | * The first time anyone tries to iterate across a cgroup, | |
1873 | * we need to enable the list linking each css_set to its | |
1874 | * tasks, and fix up all existing tasks. | |
1875 | */ | |
31a7df01 CW |
1876 | if (!use_task_css_set_links) |
1877 | cgroup_enable_task_cg_lists(); | |
1878 | ||
817929ec | 1879 | read_lock(&css_set_lock); |
bd89aabc PM |
1880 | it->cg_link = &cgrp->css_sets; |
1881 | cgroup_advance_iter(cgrp, it); | |
817929ec PM |
1882 | } |
1883 | ||
bd89aabc | 1884 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
817929ec PM |
1885 | struct cgroup_iter *it) |
1886 | { | |
1887 | struct task_struct *res; | |
1888 | struct list_head *l = it->task; | |
2019f634 | 1889 | struct cg_cgroup_link *link; |
817929ec PM |
1890 | |
1891 | /* If the iterator cg is NULL, we have no tasks */ | |
1892 | if (!it->cg_link) | |
1893 | return NULL; | |
1894 | res = list_entry(l, struct task_struct, cg_list); | |
1895 | /* Advance iterator to find next entry */ | |
1896 | l = l->next; | |
2019f634 LJ |
1897 | link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list); |
1898 | if (l == &link->cg->tasks) { | |
817929ec PM |
1899 | /* We reached the end of this task list - move on to |
1900 | * the next cg_cgroup_link */ | |
bd89aabc | 1901 | cgroup_advance_iter(cgrp, it); |
817929ec PM |
1902 | } else { |
1903 | it->task = l; | |
1904 | } | |
1905 | return res; | |
1906 | } | |
1907 | ||
bd89aabc | 1908 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it) |
817929ec PM |
1909 | { |
1910 | read_unlock(&css_set_lock); | |
1911 | } | |
1912 | ||
31a7df01 CW |
1913 | static inline int started_after_time(struct task_struct *t1, |
1914 | struct timespec *time, | |
1915 | struct task_struct *t2) | |
1916 | { | |
1917 | int start_diff = timespec_compare(&t1->start_time, time); | |
1918 | if (start_diff > 0) { | |
1919 | return 1; | |
1920 | } else if (start_diff < 0) { | |
1921 | return 0; | |
1922 | } else { | |
1923 | /* | |
1924 | * Arbitrarily, if two processes started at the same | |
1925 | * time, we'll say that the lower pointer value | |
1926 | * started first. Note that t2 may have exited by now | |
1927 | * so this may not be a valid pointer any longer, but | |
1928 | * that's fine - it still serves to distinguish | |
1929 | * between two tasks started (effectively) simultaneously. | |
1930 | */ | |
1931 | return t1 > t2; | |
1932 | } | |
1933 | } | |
1934 | ||
1935 | /* | |
1936 | * This function is a callback from heap_insert() and is used to order | |
1937 | * the heap. | |
1938 | * In this case we order the heap in descending task start time. | |
1939 | */ | |
1940 | static inline int started_after(void *p1, void *p2) | |
1941 | { | |
1942 | struct task_struct *t1 = p1; | |
1943 | struct task_struct *t2 = p2; | |
1944 | return started_after_time(t1, &t2->start_time, t2); | |
1945 | } | |
1946 | ||
1947 | /** | |
1948 | * cgroup_scan_tasks - iterate though all the tasks in a cgroup | |
1949 | * @scan: struct cgroup_scanner containing arguments for the scan | |
1950 | * | |
1951 | * Arguments include pointers to callback functions test_task() and | |
1952 | * process_task(). | |
1953 | * Iterate through all the tasks in a cgroup, calling test_task() for each, | |
1954 | * and if it returns true, call process_task() for it also. | |
1955 | * The test_task pointer may be NULL, meaning always true (select all tasks). | |
1956 | * Effectively duplicates cgroup_iter_{start,next,end}() | |
1957 | * but does not lock css_set_lock for the call to process_task(). | |
1958 | * The struct cgroup_scanner may be embedded in any structure of the caller's | |
1959 | * creation. | |
1960 | * It is guaranteed that process_task() will act on every task that | |
1961 | * is a member of the cgroup for the duration of this call. This | |
1962 | * function may or may not call process_task() for tasks that exit | |
1963 | * or move to a different cgroup during the call, or are forked or | |
1964 | * move into the cgroup during the call. | |
1965 | * | |
1966 | * Note that test_task() may be called with locks held, and may in some | |
1967 | * situations be called multiple times for the same task, so it should | |
1968 | * be cheap. | |
1969 | * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been | |
1970 | * pre-allocated and will be used for heap operations (and its "gt" member will | |
1971 | * be overwritten), else a temporary heap will be used (allocation of which | |
1972 | * may cause this function to fail). | |
1973 | */ | |
1974 | int cgroup_scan_tasks(struct cgroup_scanner *scan) | |
1975 | { | |
1976 | int retval, i; | |
1977 | struct cgroup_iter it; | |
1978 | struct task_struct *p, *dropped; | |
1979 | /* Never dereference latest_task, since it's not refcounted */ | |
1980 | struct task_struct *latest_task = NULL; | |
1981 | struct ptr_heap tmp_heap; | |
1982 | struct ptr_heap *heap; | |
1983 | struct timespec latest_time = { 0, 0 }; | |
1984 | ||
1985 | if (scan->heap) { | |
1986 | /* The caller supplied our heap and pre-allocated its memory */ | |
1987 | heap = scan->heap; | |
1988 | heap->gt = &started_after; | |
1989 | } else { | |
1990 | /* We need to allocate our own heap memory */ | |
1991 | heap = &tmp_heap; | |
1992 | retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); | |
1993 | if (retval) | |
1994 | /* cannot allocate the heap */ | |
1995 | return retval; | |
1996 | } | |
1997 | ||
1998 | again: | |
1999 | /* | |
2000 | * Scan tasks in the cgroup, using the scanner's "test_task" callback | |
2001 | * to determine which are of interest, and using the scanner's | |
2002 | * "process_task" callback to process any of them that need an update. | |
2003 | * Since we don't want to hold any locks during the task updates, | |
2004 | * gather tasks to be processed in a heap structure. | |
2005 | * The heap is sorted by descending task start time. | |
2006 | * If the statically-sized heap fills up, we overflow tasks that | |
2007 | * started later, and in future iterations only consider tasks that | |
2008 | * started after the latest task in the previous pass. This | |
2009 | * guarantees forward progress and that we don't miss any tasks. | |
2010 | */ | |
2011 | heap->size = 0; | |
2012 | cgroup_iter_start(scan->cg, &it); | |
2013 | while ((p = cgroup_iter_next(scan->cg, &it))) { | |
2014 | /* | |
2015 | * Only affect tasks that qualify per the caller's callback, | |
2016 | * if he provided one | |
2017 | */ | |
2018 | if (scan->test_task && !scan->test_task(p, scan)) | |
2019 | continue; | |
2020 | /* | |
2021 | * Only process tasks that started after the last task | |
2022 | * we processed | |
2023 | */ | |
2024 | if (!started_after_time(p, &latest_time, latest_task)) | |
2025 | continue; | |
2026 | dropped = heap_insert(heap, p); | |
2027 | if (dropped == NULL) { | |
2028 | /* | |
2029 | * The new task was inserted; the heap wasn't | |
2030 | * previously full | |
2031 | */ | |
2032 | get_task_struct(p); | |
2033 | } else if (dropped != p) { | |
2034 | /* | |
2035 | * The new task was inserted, and pushed out a | |
2036 | * different task | |
2037 | */ | |
2038 | get_task_struct(p); | |
2039 | put_task_struct(dropped); | |
2040 | } | |
2041 | /* | |
2042 | * Else the new task was newer than anything already in | |
2043 | * the heap and wasn't inserted | |
2044 | */ | |
2045 | } | |
2046 | cgroup_iter_end(scan->cg, &it); | |
2047 | ||
2048 | if (heap->size) { | |
2049 | for (i = 0; i < heap->size; i++) { | |
4fe91d51 | 2050 | struct task_struct *q = heap->ptrs[i]; |
31a7df01 | 2051 | if (i == 0) { |
4fe91d51 PJ |
2052 | latest_time = q->start_time; |
2053 | latest_task = q; | |
31a7df01 CW |
2054 | } |
2055 | /* Process the task per the caller's callback */ | |
4fe91d51 PJ |
2056 | scan->process_task(q, scan); |
2057 | put_task_struct(q); | |
31a7df01 CW |
2058 | } |
2059 | /* | |
2060 | * If we had to process any tasks at all, scan again | |
2061 | * in case some of them were in the middle of forking | |
2062 | * children that didn't get processed. | |
2063 | * Not the most efficient way to do it, but it avoids | |
2064 | * having to take callback_mutex in the fork path | |
2065 | */ | |
2066 | goto again; | |
2067 | } | |
2068 | if (heap == &tmp_heap) | |
2069 | heap_free(&tmp_heap); | |
2070 | return 0; | |
2071 | } | |
2072 | ||
bbcb81d0 PM |
2073 | /* |
2074 | * Stuff for reading the 'tasks' file. | |
2075 | * | |
2076 | * Reading this file can return large amounts of data if a cgroup has | |
2077 | * *lots* of attached tasks. So it may need several calls to read(), | |
2078 | * but we cannot guarantee that the information we produce is correct | |
2079 | * unless we produce it entirely atomically. | |
2080 | * | |
bbcb81d0 | 2081 | */ |
bbcb81d0 PM |
2082 | |
2083 | /* | |
2084 | * Load into 'pidarray' up to 'npids' of the tasks using cgroup | |
bd89aabc | 2085 | * 'cgrp'. Return actual number of pids loaded. No need to |
bbcb81d0 PM |
2086 | * task_lock(p) when reading out p->cgroup, since we're in an RCU |
2087 | * read section, so the css_set can't go away, and is | |
2088 | * immutable after creation. | |
2089 | */ | |
bd89aabc | 2090 | static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cgrp) |
bbcb81d0 | 2091 | { |
e7b80bb6 | 2092 | int n = 0, pid; |
817929ec PM |
2093 | struct cgroup_iter it; |
2094 | struct task_struct *tsk; | |
bd89aabc PM |
2095 | cgroup_iter_start(cgrp, &it); |
2096 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
817929ec PM |
2097 | if (unlikely(n == npids)) |
2098 | break; | |
e7b80bb6 G |
2099 | pid = task_pid_vnr(tsk); |
2100 | if (pid > 0) | |
2101 | pidarray[n++] = pid; | |
817929ec | 2102 | } |
bd89aabc | 2103 | cgroup_iter_end(cgrp, &it); |
bbcb81d0 PM |
2104 | return n; |
2105 | } | |
2106 | ||
846c7bb0 | 2107 | /** |
a043e3b2 | 2108 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
2109 | * @stats: cgroupstats to fill information into |
2110 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
2111 | * been requested. | |
a043e3b2 LZ |
2112 | * |
2113 | * Build and fill cgroupstats so that taskstats can export it to user | |
2114 | * space. | |
846c7bb0 BS |
2115 | */ |
2116 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
2117 | { | |
2118 | int ret = -EINVAL; | |
bd89aabc | 2119 | struct cgroup *cgrp; |
846c7bb0 BS |
2120 | struct cgroup_iter it; |
2121 | struct task_struct *tsk; | |
33d283be | 2122 | |
846c7bb0 | 2123 | /* |
33d283be LZ |
2124 | * Validate dentry by checking the superblock operations, |
2125 | * and make sure it's a directory. | |
846c7bb0 | 2126 | */ |
33d283be LZ |
2127 | if (dentry->d_sb->s_op != &cgroup_ops || |
2128 | !S_ISDIR(dentry->d_inode->i_mode)) | |
846c7bb0 BS |
2129 | goto err; |
2130 | ||
2131 | ret = 0; | |
bd89aabc | 2132 | cgrp = dentry->d_fsdata; |
846c7bb0 | 2133 | |
bd89aabc PM |
2134 | cgroup_iter_start(cgrp, &it); |
2135 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
846c7bb0 BS |
2136 | switch (tsk->state) { |
2137 | case TASK_RUNNING: | |
2138 | stats->nr_running++; | |
2139 | break; | |
2140 | case TASK_INTERRUPTIBLE: | |
2141 | stats->nr_sleeping++; | |
2142 | break; | |
2143 | case TASK_UNINTERRUPTIBLE: | |
2144 | stats->nr_uninterruptible++; | |
2145 | break; | |
2146 | case TASK_STOPPED: | |
2147 | stats->nr_stopped++; | |
2148 | break; | |
2149 | default: | |
2150 | if (delayacct_is_task_waiting_on_io(tsk)) | |
2151 | stats->nr_io_wait++; | |
2152 | break; | |
2153 | } | |
2154 | } | |
bd89aabc | 2155 | cgroup_iter_end(cgrp, &it); |
846c7bb0 | 2156 | |
846c7bb0 BS |
2157 | err: |
2158 | return ret; | |
2159 | } | |
2160 | ||
bbcb81d0 PM |
2161 | static int cmppid(const void *a, const void *b) |
2162 | { | |
2163 | return *(pid_t *)a - *(pid_t *)b; | |
2164 | } | |
2165 | ||
cc31edce | 2166 | |
bbcb81d0 | 2167 | /* |
cc31edce PM |
2168 | * seq_file methods for the "tasks" file. The seq_file position is the |
2169 | * next pid to display; the seq_file iterator is a pointer to the pid | |
2170 | * in the cgroup->tasks_pids array. | |
bbcb81d0 | 2171 | */ |
cc31edce PM |
2172 | |
2173 | static void *cgroup_tasks_start(struct seq_file *s, loff_t *pos) | |
bbcb81d0 | 2174 | { |
cc31edce PM |
2175 | /* |
2176 | * Initially we receive a position value that corresponds to | |
2177 | * one more than the last pid shown (or 0 on the first call or | |
2178 | * after a seek to the start). Use a binary-search to find the | |
2179 | * next pid to display, if any | |
2180 | */ | |
2181 | struct cgroup *cgrp = s->private; | |
2182 | int index = 0, pid = *pos; | |
2183 | int *iter; | |
2184 | ||
2185 | down_read(&cgrp->pids_mutex); | |
2186 | if (pid) { | |
2187 | int end = cgrp->pids_length; | |
20777766 | 2188 | |
cc31edce PM |
2189 | while (index < end) { |
2190 | int mid = (index + end) / 2; | |
2191 | if (cgrp->tasks_pids[mid] == pid) { | |
2192 | index = mid; | |
2193 | break; | |
2194 | } else if (cgrp->tasks_pids[mid] <= pid) | |
2195 | index = mid + 1; | |
2196 | else | |
2197 | end = mid; | |
2198 | } | |
2199 | } | |
2200 | /* If we're off the end of the array, we're done */ | |
2201 | if (index >= cgrp->pids_length) | |
2202 | return NULL; | |
2203 | /* Update the abstract position to be the actual pid that we found */ | |
2204 | iter = cgrp->tasks_pids + index; | |
2205 | *pos = *iter; | |
2206 | return iter; | |
2207 | } | |
2208 | ||
2209 | static void cgroup_tasks_stop(struct seq_file *s, void *v) | |
2210 | { | |
2211 | struct cgroup *cgrp = s->private; | |
2212 | up_read(&cgrp->pids_mutex); | |
2213 | } | |
2214 | ||
2215 | static void *cgroup_tasks_next(struct seq_file *s, void *v, loff_t *pos) | |
2216 | { | |
2217 | struct cgroup *cgrp = s->private; | |
2218 | int *p = v; | |
2219 | int *end = cgrp->tasks_pids + cgrp->pids_length; | |
2220 | ||
2221 | /* | |
2222 | * Advance to the next pid in the array. If this goes off the | |
2223 | * end, we're done | |
2224 | */ | |
2225 | p++; | |
2226 | if (p >= end) { | |
2227 | return NULL; | |
2228 | } else { | |
2229 | *pos = *p; | |
2230 | return p; | |
2231 | } | |
2232 | } | |
2233 | ||
2234 | static int cgroup_tasks_show(struct seq_file *s, void *v) | |
2235 | { | |
2236 | return seq_printf(s, "%d\n", *(int *)v); | |
2237 | } | |
bbcb81d0 | 2238 | |
cc31edce PM |
2239 | static struct seq_operations cgroup_tasks_seq_operations = { |
2240 | .start = cgroup_tasks_start, | |
2241 | .stop = cgroup_tasks_stop, | |
2242 | .next = cgroup_tasks_next, | |
2243 | .show = cgroup_tasks_show, | |
2244 | }; | |
2245 | ||
2246 | static void release_cgroup_pid_array(struct cgroup *cgrp) | |
2247 | { | |
2248 | down_write(&cgrp->pids_mutex); | |
2249 | BUG_ON(!cgrp->pids_use_count); | |
2250 | if (!--cgrp->pids_use_count) { | |
2251 | kfree(cgrp->tasks_pids); | |
2252 | cgrp->tasks_pids = NULL; | |
2253 | cgrp->pids_length = 0; | |
2254 | } | |
2255 | up_write(&cgrp->pids_mutex); | |
bbcb81d0 PM |
2256 | } |
2257 | ||
cc31edce PM |
2258 | static int cgroup_tasks_release(struct inode *inode, struct file *file) |
2259 | { | |
2260 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); | |
2261 | ||
2262 | if (!(file->f_mode & FMODE_READ)) | |
2263 | return 0; | |
2264 | ||
2265 | release_cgroup_pid_array(cgrp); | |
2266 | return seq_release(inode, file); | |
2267 | } | |
2268 | ||
2269 | static struct file_operations cgroup_tasks_operations = { | |
2270 | .read = seq_read, | |
2271 | .llseek = seq_lseek, | |
2272 | .write = cgroup_file_write, | |
2273 | .release = cgroup_tasks_release, | |
2274 | }; | |
2275 | ||
bbcb81d0 | 2276 | /* |
cc31edce | 2277 | * Handle an open on 'tasks' file. Prepare an array containing the |
bbcb81d0 | 2278 | * process id's of tasks currently attached to the cgroup being opened. |
bbcb81d0 | 2279 | */ |
cc31edce | 2280 | |
bbcb81d0 PM |
2281 | static int cgroup_tasks_open(struct inode *unused, struct file *file) |
2282 | { | |
bd89aabc | 2283 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
bbcb81d0 PM |
2284 | pid_t *pidarray; |
2285 | int npids; | |
cc31edce | 2286 | int retval; |
bbcb81d0 | 2287 | |
cc31edce | 2288 | /* Nothing to do for write-only files */ |
bbcb81d0 PM |
2289 | if (!(file->f_mode & FMODE_READ)) |
2290 | return 0; | |
2291 | ||
bbcb81d0 PM |
2292 | /* |
2293 | * If cgroup gets more users after we read count, we won't have | |
2294 | * enough space - tough. This race is indistinguishable to the | |
2295 | * caller from the case that the additional cgroup users didn't | |
2296 | * show up until sometime later on. | |
2297 | */ | |
bd89aabc | 2298 | npids = cgroup_task_count(cgrp); |
cc31edce PM |
2299 | pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL); |
2300 | if (!pidarray) | |
2301 | return -ENOMEM; | |
2302 | npids = pid_array_load(pidarray, npids, cgrp); | |
2303 | sort(pidarray, npids, sizeof(pid_t), cmppid, NULL); | |
bbcb81d0 | 2304 | |
cc31edce PM |
2305 | /* |
2306 | * Store the array in the cgroup, freeing the old | |
2307 | * array if necessary | |
2308 | */ | |
2309 | down_write(&cgrp->pids_mutex); | |
2310 | kfree(cgrp->tasks_pids); | |
2311 | cgrp->tasks_pids = pidarray; | |
2312 | cgrp->pids_length = npids; | |
2313 | cgrp->pids_use_count++; | |
2314 | up_write(&cgrp->pids_mutex); | |
2315 | ||
2316 | file->f_op = &cgroup_tasks_operations; | |
2317 | ||
2318 | retval = seq_open(file, &cgroup_tasks_seq_operations); | |
2319 | if (retval) { | |
2320 | release_cgroup_pid_array(cgrp); | |
2321 | return retval; | |
bbcb81d0 | 2322 | } |
cc31edce | 2323 | ((struct seq_file *)file->private_data)->private = cgrp; |
bbcb81d0 PM |
2324 | return 0; |
2325 | } | |
2326 | ||
bd89aabc | 2327 | static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, |
81a6a5cd PM |
2328 | struct cftype *cft) |
2329 | { | |
bd89aabc | 2330 | return notify_on_release(cgrp); |
81a6a5cd PM |
2331 | } |
2332 | ||
6379c106 PM |
2333 | static int cgroup_write_notify_on_release(struct cgroup *cgrp, |
2334 | struct cftype *cft, | |
2335 | u64 val) | |
2336 | { | |
2337 | clear_bit(CGRP_RELEASABLE, &cgrp->flags); | |
2338 | if (val) | |
2339 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
2340 | else | |
2341 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
2342 | return 0; | |
2343 | } | |
2344 | ||
bbcb81d0 PM |
2345 | /* |
2346 | * for the common functions, 'private' gives the type of file | |
2347 | */ | |
81a6a5cd PM |
2348 | static struct cftype files[] = { |
2349 | { | |
2350 | .name = "tasks", | |
2351 | .open = cgroup_tasks_open, | |
af351026 | 2352 | .write_u64 = cgroup_tasks_write, |
81a6a5cd PM |
2353 | .release = cgroup_tasks_release, |
2354 | .private = FILE_TASKLIST, | |
2355 | }, | |
2356 | ||
2357 | { | |
2358 | .name = "notify_on_release", | |
f4c753b7 | 2359 | .read_u64 = cgroup_read_notify_on_release, |
6379c106 | 2360 | .write_u64 = cgroup_write_notify_on_release, |
81a6a5cd PM |
2361 | .private = FILE_NOTIFY_ON_RELEASE, |
2362 | }, | |
81a6a5cd PM |
2363 | }; |
2364 | ||
2365 | static struct cftype cft_release_agent = { | |
2366 | .name = "release_agent", | |
e788e066 PM |
2367 | .read_seq_string = cgroup_release_agent_show, |
2368 | .write_string = cgroup_release_agent_write, | |
2369 | .max_write_len = PATH_MAX, | |
81a6a5cd | 2370 | .private = FILE_RELEASE_AGENT, |
bbcb81d0 PM |
2371 | }; |
2372 | ||
bd89aabc | 2373 | static int cgroup_populate_dir(struct cgroup *cgrp) |
ddbcc7e8 PM |
2374 | { |
2375 | int err; | |
2376 | struct cgroup_subsys *ss; | |
2377 | ||
2378 | /* First clear out any existing files */ | |
bd89aabc | 2379 | cgroup_clear_directory(cgrp->dentry); |
ddbcc7e8 | 2380 | |
bd89aabc | 2381 | err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files)); |
bbcb81d0 PM |
2382 | if (err < 0) |
2383 | return err; | |
2384 | ||
bd89aabc PM |
2385 | if (cgrp == cgrp->top_cgroup) { |
2386 | if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0) | |
81a6a5cd PM |
2387 | return err; |
2388 | } | |
2389 | ||
bd89aabc PM |
2390 | for_each_subsys(cgrp->root, ss) { |
2391 | if (ss->populate && (err = ss->populate(ss, cgrp)) < 0) | |
ddbcc7e8 PM |
2392 | return err; |
2393 | } | |
38460b48 KH |
2394 | /* This cgroup is ready now */ |
2395 | for_each_subsys(cgrp->root, ss) { | |
2396 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
2397 | /* | |
2398 | * Update id->css pointer and make this css visible from | |
2399 | * CSS ID functions. This pointer will be dereferened | |
2400 | * from RCU-read-side without locks. | |
2401 | */ | |
2402 | if (css->id) | |
2403 | rcu_assign_pointer(css->id->css, css); | |
2404 | } | |
ddbcc7e8 PM |
2405 | |
2406 | return 0; | |
2407 | } | |
2408 | ||
2409 | static void init_cgroup_css(struct cgroup_subsys_state *css, | |
2410 | struct cgroup_subsys *ss, | |
bd89aabc | 2411 | struct cgroup *cgrp) |
ddbcc7e8 | 2412 | { |
bd89aabc | 2413 | css->cgroup = cgrp; |
e7c5ec91 | 2414 | atomic_set(&css->refcnt, 1); |
ddbcc7e8 | 2415 | css->flags = 0; |
38460b48 | 2416 | css->id = NULL; |
bd89aabc | 2417 | if (cgrp == dummytop) |
ddbcc7e8 | 2418 | set_bit(CSS_ROOT, &css->flags); |
bd89aabc PM |
2419 | BUG_ON(cgrp->subsys[ss->subsys_id]); |
2420 | cgrp->subsys[ss->subsys_id] = css; | |
ddbcc7e8 PM |
2421 | } |
2422 | ||
999cd8a4 PM |
2423 | static void cgroup_lock_hierarchy(struct cgroupfs_root *root) |
2424 | { | |
2425 | /* We need to take each hierarchy_mutex in a consistent order */ | |
2426 | int i; | |
2427 | ||
2428 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
2429 | struct cgroup_subsys *ss = subsys[i]; | |
2430 | if (ss->root == root) | |
cfebe563 | 2431 | mutex_lock(&ss->hierarchy_mutex); |
999cd8a4 PM |
2432 | } |
2433 | } | |
2434 | ||
2435 | static void cgroup_unlock_hierarchy(struct cgroupfs_root *root) | |
2436 | { | |
2437 | int i; | |
2438 | ||
2439 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
2440 | struct cgroup_subsys *ss = subsys[i]; | |
2441 | if (ss->root == root) | |
2442 | mutex_unlock(&ss->hierarchy_mutex); | |
2443 | } | |
2444 | } | |
2445 | ||
ddbcc7e8 | 2446 | /* |
a043e3b2 LZ |
2447 | * cgroup_create - create a cgroup |
2448 | * @parent: cgroup that will be parent of the new cgroup | |
2449 | * @dentry: dentry of the new cgroup | |
2450 | * @mode: mode to set on new inode | |
ddbcc7e8 | 2451 | * |
a043e3b2 | 2452 | * Must be called with the mutex on the parent inode held |
ddbcc7e8 | 2453 | */ |
ddbcc7e8 PM |
2454 | static long cgroup_create(struct cgroup *parent, struct dentry *dentry, |
2455 | int mode) | |
2456 | { | |
bd89aabc | 2457 | struct cgroup *cgrp; |
ddbcc7e8 PM |
2458 | struct cgroupfs_root *root = parent->root; |
2459 | int err = 0; | |
2460 | struct cgroup_subsys *ss; | |
2461 | struct super_block *sb = root->sb; | |
2462 | ||
bd89aabc PM |
2463 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
2464 | if (!cgrp) | |
ddbcc7e8 PM |
2465 | return -ENOMEM; |
2466 | ||
2467 | /* Grab a reference on the superblock so the hierarchy doesn't | |
2468 | * get deleted on unmount if there are child cgroups. This | |
2469 | * can be done outside cgroup_mutex, since the sb can't | |
2470 | * disappear while someone has an open control file on the | |
2471 | * fs */ | |
2472 | atomic_inc(&sb->s_active); | |
2473 | ||
2474 | mutex_lock(&cgroup_mutex); | |
2475 | ||
cc31edce | 2476 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 2477 | |
bd89aabc PM |
2478 | cgrp->parent = parent; |
2479 | cgrp->root = parent->root; | |
2480 | cgrp->top_cgroup = parent->top_cgroup; | |
ddbcc7e8 | 2481 | |
b6abdb0e LZ |
2482 | if (notify_on_release(parent)) |
2483 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
2484 | ||
ddbcc7e8 | 2485 | for_each_subsys(root, ss) { |
bd89aabc | 2486 | struct cgroup_subsys_state *css = ss->create(ss, cgrp); |
ddbcc7e8 PM |
2487 | if (IS_ERR(css)) { |
2488 | err = PTR_ERR(css); | |
2489 | goto err_destroy; | |
2490 | } | |
bd89aabc | 2491 | init_cgroup_css(css, ss, cgrp); |
38460b48 KH |
2492 | if (ss->use_id) |
2493 | if (alloc_css_id(ss, parent, cgrp)) | |
2494 | goto err_destroy; | |
2495 | /* At error, ->destroy() callback has to free assigned ID. */ | |
ddbcc7e8 PM |
2496 | } |
2497 | ||
999cd8a4 | 2498 | cgroup_lock_hierarchy(root); |
bd89aabc | 2499 | list_add(&cgrp->sibling, &cgrp->parent->children); |
999cd8a4 | 2500 | cgroup_unlock_hierarchy(root); |
ddbcc7e8 PM |
2501 | root->number_of_cgroups++; |
2502 | ||
bd89aabc | 2503 | err = cgroup_create_dir(cgrp, dentry, mode); |
ddbcc7e8 PM |
2504 | if (err < 0) |
2505 | goto err_remove; | |
2506 | ||
2507 | /* The cgroup directory was pre-locked for us */ | |
bd89aabc | 2508 | BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); |
ddbcc7e8 | 2509 | |
bd89aabc | 2510 | err = cgroup_populate_dir(cgrp); |
ddbcc7e8 PM |
2511 | /* If err < 0, we have a half-filled directory - oh well ;) */ |
2512 | ||
2513 | mutex_unlock(&cgroup_mutex); | |
bd89aabc | 2514 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
2515 | |
2516 | return 0; | |
2517 | ||
2518 | err_remove: | |
2519 | ||
baef99a0 | 2520 | cgroup_lock_hierarchy(root); |
bd89aabc | 2521 | list_del(&cgrp->sibling); |
baef99a0 | 2522 | cgroup_unlock_hierarchy(root); |
ddbcc7e8 PM |
2523 | root->number_of_cgroups--; |
2524 | ||
2525 | err_destroy: | |
2526 | ||
2527 | for_each_subsys(root, ss) { | |
bd89aabc PM |
2528 | if (cgrp->subsys[ss->subsys_id]) |
2529 | ss->destroy(ss, cgrp); | |
ddbcc7e8 PM |
2530 | } |
2531 | ||
2532 | mutex_unlock(&cgroup_mutex); | |
2533 | ||
2534 | /* Release the reference count that we took on the superblock */ | |
2535 | deactivate_super(sb); | |
2536 | ||
bd89aabc | 2537 | kfree(cgrp); |
ddbcc7e8 PM |
2538 | return err; |
2539 | } | |
2540 | ||
2541 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode) | |
2542 | { | |
2543 | struct cgroup *c_parent = dentry->d_parent->d_fsdata; | |
2544 | ||
2545 | /* the vfs holds inode->i_mutex already */ | |
2546 | return cgroup_create(c_parent, dentry, mode | S_IFDIR); | |
2547 | } | |
2548 | ||
55b6fd01 | 2549 | static int cgroup_has_css_refs(struct cgroup *cgrp) |
81a6a5cd PM |
2550 | { |
2551 | /* Check the reference count on each subsystem. Since we | |
2552 | * already established that there are no tasks in the | |
e7c5ec91 | 2553 | * cgroup, if the css refcount is also 1, then there should |
81a6a5cd PM |
2554 | * be no outstanding references, so the subsystem is safe to |
2555 | * destroy. We scan across all subsystems rather than using | |
2556 | * the per-hierarchy linked list of mounted subsystems since | |
2557 | * we can be called via check_for_release() with no | |
2558 | * synchronization other than RCU, and the subsystem linked | |
2559 | * list isn't RCU-safe */ | |
2560 | int i; | |
2561 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
2562 | struct cgroup_subsys *ss = subsys[i]; | |
2563 | struct cgroup_subsys_state *css; | |
2564 | /* Skip subsystems not in this hierarchy */ | |
bd89aabc | 2565 | if (ss->root != cgrp->root) |
81a6a5cd | 2566 | continue; |
bd89aabc | 2567 | css = cgrp->subsys[ss->subsys_id]; |
81a6a5cd PM |
2568 | /* When called from check_for_release() it's possible |
2569 | * that by this point the cgroup has been removed | |
2570 | * and the css deleted. But a false-positive doesn't | |
2571 | * matter, since it can only happen if the cgroup | |
2572 | * has been deleted and hence no longer needs the | |
2573 | * release agent to be called anyway. */ | |
e7c5ec91 | 2574 | if (css && (atomic_read(&css->refcnt) > 1)) |
81a6a5cd | 2575 | return 1; |
81a6a5cd PM |
2576 | } |
2577 | return 0; | |
2578 | } | |
2579 | ||
e7c5ec91 PM |
2580 | /* |
2581 | * Atomically mark all (or else none) of the cgroup's CSS objects as | |
2582 | * CSS_REMOVED. Return true on success, or false if the cgroup has | |
2583 | * busy subsystems. Call with cgroup_mutex held | |
2584 | */ | |
2585 | ||
2586 | static int cgroup_clear_css_refs(struct cgroup *cgrp) | |
2587 | { | |
2588 | struct cgroup_subsys *ss; | |
2589 | unsigned long flags; | |
2590 | bool failed = false; | |
2591 | local_irq_save(flags); | |
2592 | for_each_subsys(cgrp->root, ss) { | |
2593 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
2594 | int refcnt; | |
804b3c28 | 2595 | while (1) { |
e7c5ec91 PM |
2596 | /* We can only remove a CSS with a refcnt==1 */ |
2597 | refcnt = atomic_read(&css->refcnt); | |
2598 | if (refcnt > 1) { | |
2599 | failed = true; | |
2600 | goto done; | |
2601 | } | |
2602 | BUG_ON(!refcnt); | |
2603 | /* | |
2604 | * Drop the refcnt to 0 while we check other | |
2605 | * subsystems. This will cause any racing | |
2606 | * css_tryget() to spin until we set the | |
2607 | * CSS_REMOVED bits or abort | |
2608 | */ | |
804b3c28 PM |
2609 | if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt) |
2610 | break; | |
2611 | cpu_relax(); | |
2612 | } | |
e7c5ec91 PM |
2613 | } |
2614 | done: | |
2615 | for_each_subsys(cgrp->root, ss) { | |
2616 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
2617 | if (failed) { | |
2618 | /* | |
2619 | * Restore old refcnt if we previously managed | |
2620 | * to clear it from 1 to 0 | |
2621 | */ | |
2622 | if (!atomic_read(&css->refcnt)) | |
2623 | atomic_set(&css->refcnt, 1); | |
2624 | } else { | |
2625 | /* Commit the fact that the CSS is removed */ | |
2626 | set_bit(CSS_REMOVED, &css->flags); | |
2627 | } | |
2628 | } | |
2629 | local_irq_restore(flags); | |
2630 | return !failed; | |
2631 | } | |
2632 | ||
ddbcc7e8 PM |
2633 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) |
2634 | { | |
bd89aabc | 2635 | struct cgroup *cgrp = dentry->d_fsdata; |
ddbcc7e8 PM |
2636 | struct dentry *d; |
2637 | struct cgroup *parent; | |
ec64f515 KH |
2638 | DEFINE_WAIT(wait); |
2639 | int ret; | |
ddbcc7e8 PM |
2640 | |
2641 | /* the vfs holds both inode->i_mutex already */ | |
ec64f515 | 2642 | again: |
ddbcc7e8 | 2643 | mutex_lock(&cgroup_mutex); |
bd89aabc | 2644 | if (atomic_read(&cgrp->count) != 0) { |
ddbcc7e8 PM |
2645 | mutex_unlock(&cgroup_mutex); |
2646 | return -EBUSY; | |
2647 | } | |
bd89aabc | 2648 | if (!list_empty(&cgrp->children)) { |
ddbcc7e8 PM |
2649 | mutex_unlock(&cgroup_mutex); |
2650 | return -EBUSY; | |
2651 | } | |
3fa59dfb | 2652 | mutex_unlock(&cgroup_mutex); |
a043e3b2 | 2653 | |
4fca88c8 | 2654 | /* |
a043e3b2 LZ |
2655 | * Call pre_destroy handlers of subsys. Notify subsystems |
2656 | * that rmdir() request comes. | |
4fca88c8 | 2657 | */ |
ec64f515 KH |
2658 | ret = cgroup_call_pre_destroy(cgrp); |
2659 | if (ret) | |
2660 | return ret; | |
ddbcc7e8 | 2661 | |
3fa59dfb KH |
2662 | mutex_lock(&cgroup_mutex); |
2663 | parent = cgrp->parent; | |
ec64f515 | 2664 | if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) { |
ddbcc7e8 PM |
2665 | mutex_unlock(&cgroup_mutex); |
2666 | return -EBUSY; | |
2667 | } | |
ec64f515 KH |
2668 | /* |
2669 | * css_put/get is provided for subsys to grab refcnt to css. In typical | |
2670 | * case, subsystem has no reference after pre_destroy(). But, under | |
2671 | * hierarchy management, some *temporal* refcnt can be hold. | |
2672 | * To avoid returning -EBUSY to a user, waitqueue is used. If subsys | |
2673 | * is really busy, it should return -EBUSY at pre_destroy(). wake_up | |
2674 | * is called when css_put() is called and refcnt goes down to 0. | |
2675 | */ | |
2676 | set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
2677 | prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE); | |
2678 | ||
2679 | if (!cgroup_clear_css_refs(cgrp)) { | |
2680 | mutex_unlock(&cgroup_mutex); | |
2681 | schedule(); | |
2682 | finish_wait(&cgroup_rmdir_waitq, &wait); | |
2683 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
2684 | if (signal_pending(current)) | |
2685 | return -EINTR; | |
2686 | goto again; | |
2687 | } | |
2688 | /* NO css_tryget() can success after here. */ | |
2689 | finish_wait(&cgroup_rmdir_waitq, &wait); | |
2690 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
ddbcc7e8 | 2691 | |
81a6a5cd | 2692 | spin_lock(&release_list_lock); |
bd89aabc PM |
2693 | set_bit(CGRP_REMOVED, &cgrp->flags); |
2694 | if (!list_empty(&cgrp->release_list)) | |
2695 | list_del(&cgrp->release_list); | |
81a6a5cd | 2696 | spin_unlock(&release_list_lock); |
999cd8a4 PM |
2697 | |
2698 | cgroup_lock_hierarchy(cgrp->root); | |
2699 | /* delete this cgroup from parent->children */ | |
bd89aabc | 2700 | list_del(&cgrp->sibling); |
999cd8a4 PM |
2701 | cgroup_unlock_hierarchy(cgrp->root); |
2702 | ||
bd89aabc PM |
2703 | spin_lock(&cgrp->dentry->d_lock); |
2704 | d = dget(cgrp->dentry); | |
ddbcc7e8 PM |
2705 | spin_unlock(&d->d_lock); |
2706 | ||
2707 | cgroup_d_remove_dir(d); | |
2708 | dput(d); | |
ddbcc7e8 | 2709 | |
bd89aabc | 2710 | set_bit(CGRP_RELEASABLE, &parent->flags); |
81a6a5cd PM |
2711 | check_for_release(parent); |
2712 | ||
ddbcc7e8 | 2713 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
2714 | return 0; |
2715 | } | |
2716 | ||
06a11920 | 2717 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
ddbcc7e8 | 2718 | { |
ddbcc7e8 | 2719 | struct cgroup_subsys_state *css; |
cfe36bde DC |
2720 | |
2721 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 PM |
2722 | |
2723 | /* Create the top cgroup state for this subsystem */ | |
33a68ac1 | 2724 | list_add(&ss->sibling, &rootnode.subsys_list); |
ddbcc7e8 PM |
2725 | ss->root = &rootnode; |
2726 | css = ss->create(ss, dummytop); | |
2727 | /* We don't handle early failures gracefully */ | |
2728 | BUG_ON(IS_ERR(css)); | |
2729 | init_cgroup_css(css, ss, dummytop); | |
2730 | ||
e8d55fde | 2731 | /* Update the init_css_set to contain a subsys |
817929ec | 2732 | * pointer to this state - since the subsystem is |
e8d55fde LZ |
2733 | * newly registered, all tasks and hence the |
2734 | * init_css_set is in the subsystem's top cgroup. */ | |
2735 | init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id]; | |
ddbcc7e8 PM |
2736 | |
2737 | need_forkexit_callback |= ss->fork || ss->exit; | |
2738 | ||
e8d55fde LZ |
2739 | /* At system boot, before all subsystems have been |
2740 | * registered, no tasks have been forked, so we don't | |
2741 | * need to invoke fork callbacks here. */ | |
2742 | BUG_ON(!list_empty(&init_task.tasks)); | |
2743 | ||
999cd8a4 | 2744 | mutex_init(&ss->hierarchy_mutex); |
cfebe563 | 2745 | lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); |
ddbcc7e8 PM |
2746 | ss->active = 1; |
2747 | } | |
2748 | ||
2749 | /** | |
a043e3b2 LZ |
2750 | * cgroup_init_early - cgroup initialization at system boot |
2751 | * | |
2752 | * Initialize cgroups at system boot, and initialize any | |
2753 | * subsystems that request early init. | |
ddbcc7e8 PM |
2754 | */ |
2755 | int __init cgroup_init_early(void) | |
2756 | { | |
2757 | int i; | |
146aa1bd | 2758 | atomic_set(&init_css_set.refcount, 1); |
817929ec PM |
2759 | INIT_LIST_HEAD(&init_css_set.cg_links); |
2760 | INIT_LIST_HEAD(&init_css_set.tasks); | |
472b1053 | 2761 | INIT_HLIST_NODE(&init_css_set.hlist); |
817929ec | 2762 | css_set_count = 1; |
ddbcc7e8 | 2763 | init_cgroup_root(&rootnode); |
817929ec PM |
2764 | root_count = 1; |
2765 | init_task.cgroups = &init_css_set; | |
2766 | ||
2767 | init_css_set_link.cg = &init_css_set; | |
bd89aabc | 2768 | list_add(&init_css_set_link.cgrp_link_list, |
817929ec PM |
2769 | &rootnode.top_cgroup.css_sets); |
2770 | list_add(&init_css_set_link.cg_link_list, | |
2771 | &init_css_set.cg_links); | |
ddbcc7e8 | 2772 | |
472b1053 LZ |
2773 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) |
2774 | INIT_HLIST_HEAD(&css_set_table[i]); | |
2775 | ||
ddbcc7e8 PM |
2776 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
2777 | struct cgroup_subsys *ss = subsys[i]; | |
2778 | ||
2779 | BUG_ON(!ss->name); | |
2780 | BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); | |
2781 | BUG_ON(!ss->create); | |
2782 | BUG_ON(!ss->destroy); | |
2783 | if (ss->subsys_id != i) { | |
cfe36bde | 2784 | printk(KERN_ERR "cgroup: Subsys %s id == %d\n", |
ddbcc7e8 PM |
2785 | ss->name, ss->subsys_id); |
2786 | BUG(); | |
2787 | } | |
2788 | ||
2789 | if (ss->early_init) | |
2790 | cgroup_init_subsys(ss); | |
2791 | } | |
2792 | return 0; | |
2793 | } | |
2794 | ||
2795 | /** | |
a043e3b2 LZ |
2796 | * cgroup_init - cgroup initialization |
2797 | * | |
2798 | * Register cgroup filesystem and /proc file, and initialize | |
2799 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
2800 | */ |
2801 | int __init cgroup_init(void) | |
2802 | { | |
2803 | int err; | |
2804 | int i; | |
472b1053 | 2805 | struct hlist_head *hhead; |
a424316c PM |
2806 | |
2807 | err = bdi_init(&cgroup_backing_dev_info); | |
2808 | if (err) | |
2809 | return err; | |
ddbcc7e8 PM |
2810 | |
2811 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
2812 | struct cgroup_subsys *ss = subsys[i]; | |
2813 | if (!ss->early_init) | |
2814 | cgroup_init_subsys(ss); | |
38460b48 KH |
2815 | if (ss->use_id) |
2816 | cgroup_subsys_init_idr(ss); | |
ddbcc7e8 PM |
2817 | } |
2818 | ||
472b1053 LZ |
2819 | /* Add init_css_set to the hash table */ |
2820 | hhead = css_set_hash(init_css_set.subsys); | |
2821 | hlist_add_head(&init_css_set.hlist, hhead); | |
2822 | ||
ddbcc7e8 PM |
2823 | err = register_filesystem(&cgroup_fs_type); |
2824 | if (err < 0) | |
2825 | goto out; | |
2826 | ||
46ae220b | 2827 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
a424316c | 2828 | |
ddbcc7e8 | 2829 | out: |
a424316c PM |
2830 | if (err) |
2831 | bdi_destroy(&cgroup_backing_dev_info); | |
2832 | ||
ddbcc7e8 PM |
2833 | return err; |
2834 | } | |
b4f48b63 | 2835 | |
a424316c PM |
2836 | /* |
2837 | * proc_cgroup_show() | |
2838 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
2839 | * - Used for /proc/<pid>/cgroup. | |
2840 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it | |
2841 | * doesn't really matter if tsk->cgroup changes after we read it, | |
956db3ca | 2842 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it |
a424316c PM |
2843 | * anyway. No need to check that tsk->cgroup != NULL, thanks to |
2844 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks | |
2845 | * cgroup to top_cgroup. | |
2846 | */ | |
2847 | ||
2848 | /* TODO: Use a proper seq_file iterator */ | |
2849 | static int proc_cgroup_show(struct seq_file *m, void *v) | |
2850 | { | |
2851 | struct pid *pid; | |
2852 | struct task_struct *tsk; | |
2853 | char *buf; | |
2854 | int retval; | |
2855 | struct cgroupfs_root *root; | |
2856 | ||
2857 | retval = -ENOMEM; | |
2858 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
2859 | if (!buf) | |
2860 | goto out; | |
2861 | ||
2862 | retval = -ESRCH; | |
2863 | pid = m->private; | |
2864 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
2865 | if (!tsk) | |
2866 | goto out_free; | |
2867 | ||
2868 | retval = 0; | |
2869 | ||
2870 | mutex_lock(&cgroup_mutex); | |
2871 | ||
e5f6a860 | 2872 | for_each_active_root(root) { |
a424316c | 2873 | struct cgroup_subsys *ss; |
bd89aabc | 2874 | struct cgroup *cgrp; |
a424316c PM |
2875 | int subsys_id; |
2876 | int count = 0; | |
2877 | ||
b6c3006d | 2878 | seq_printf(m, "%lu:", root->subsys_bits); |
a424316c PM |
2879 | for_each_subsys(root, ss) |
2880 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); | |
2881 | seq_putc(m, ':'); | |
2882 | get_first_subsys(&root->top_cgroup, NULL, &subsys_id); | |
bd89aabc PM |
2883 | cgrp = task_cgroup(tsk, subsys_id); |
2884 | retval = cgroup_path(cgrp, buf, PAGE_SIZE); | |
a424316c PM |
2885 | if (retval < 0) |
2886 | goto out_unlock; | |
2887 | seq_puts(m, buf); | |
2888 | seq_putc(m, '\n'); | |
2889 | } | |
2890 | ||
2891 | out_unlock: | |
2892 | mutex_unlock(&cgroup_mutex); | |
2893 | put_task_struct(tsk); | |
2894 | out_free: | |
2895 | kfree(buf); | |
2896 | out: | |
2897 | return retval; | |
2898 | } | |
2899 | ||
2900 | static int cgroup_open(struct inode *inode, struct file *file) | |
2901 | { | |
2902 | struct pid *pid = PROC_I(inode)->pid; | |
2903 | return single_open(file, proc_cgroup_show, pid); | |
2904 | } | |
2905 | ||
2906 | struct file_operations proc_cgroup_operations = { | |
2907 | .open = cgroup_open, | |
2908 | .read = seq_read, | |
2909 | .llseek = seq_lseek, | |
2910 | .release = single_release, | |
2911 | }; | |
2912 | ||
2913 | /* Display information about each subsystem and each hierarchy */ | |
2914 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
2915 | { | |
2916 | int i; | |
a424316c | 2917 | |
8bab8dde | 2918 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
a424316c | 2919 | mutex_lock(&cgroup_mutex); |
a424316c PM |
2920 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
2921 | struct cgroup_subsys *ss = subsys[i]; | |
8bab8dde | 2922 | seq_printf(m, "%s\t%lu\t%d\t%d\n", |
817929ec | 2923 | ss->name, ss->root->subsys_bits, |
8bab8dde | 2924 | ss->root->number_of_cgroups, !ss->disabled); |
a424316c PM |
2925 | } |
2926 | mutex_unlock(&cgroup_mutex); | |
2927 | return 0; | |
2928 | } | |
2929 | ||
2930 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
2931 | { | |
9dce07f1 | 2932 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
2933 | } |
2934 | ||
2935 | static struct file_operations proc_cgroupstats_operations = { | |
2936 | .open = cgroupstats_open, | |
2937 | .read = seq_read, | |
2938 | .llseek = seq_lseek, | |
2939 | .release = single_release, | |
2940 | }; | |
2941 | ||
b4f48b63 PM |
2942 | /** |
2943 | * cgroup_fork - attach newly forked task to its parents cgroup. | |
a043e3b2 | 2944 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 PM |
2945 | * |
2946 | * Description: A task inherits its parent's cgroup at fork(). | |
2947 | * | |
2948 | * A pointer to the shared css_set was automatically copied in | |
2949 | * fork.c by dup_task_struct(). However, we ignore that copy, since | |
2950 | * it was not made under the protection of RCU or cgroup_mutex, so | |
956db3ca | 2951 | * might no longer be a valid cgroup pointer. cgroup_attach_task() might |
817929ec PM |
2952 | * have already changed current->cgroups, allowing the previously |
2953 | * referenced cgroup group to be removed and freed. | |
b4f48b63 PM |
2954 | * |
2955 | * At the point that cgroup_fork() is called, 'current' is the parent | |
2956 | * task, and the passed argument 'child' points to the child task. | |
2957 | */ | |
2958 | void cgroup_fork(struct task_struct *child) | |
2959 | { | |
817929ec PM |
2960 | task_lock(current); |
2961 | child->cgroups = current->cgroups; | |
2962 | get_css_set(child->cgroups); | |
2963 | task_unlock(current); | |
2964 | INIT_LIST_HEAD(&child->cg_list); | |
b4f48b63 PM |
2965 | } |
2966 | ||
2967 | /** | |
a043e3b2 LZ |
2968 | * cgroup_fork_callbacks - run fork callbacks |
2969 | * @child: the new task | |
2970 | * | |
2971 | * Called on a new task very soon before adding it to the | |
2972 | * tasklist. No need to take any locks since no-one can | |
2973 | * be operating on this task. | |
b4f48b63 PM |
2974 | */ |
2975 | void cgroup_fork_callbacks(struct task_struct *child) | |
2976 | { | |
2977 | if (need_forkexit_callback) { | |
2978 | int i; | |
2979 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
2980 | struct cgroup_subsys *ss = subsys[i]; | |
2981 | if (ss->fork) | |
2982 | ss->fork(ss, child); | |
2983 | } | |
2984 | } | |
2985 | } | |
2986 | ||
817929ec | 2987 | /** |
a043e3b2 LZ |
2988 | * cgroup_post_fork - called on a new task after adding it to the task list |
2989 | * @child: the task in question | |
2990 | * | |
2991 | * Adds the task to the list running through its css_set if necessary. | |
2992 | * Has to be after the task is visible on the task list in case we race | |
2993 | * with the first call to cgroup_iter_start() - to guarantee that the | |
2994 | * new task ends up on its list. | |
2995 | */ | |
817929ec PM |
2996 | void cgroup_post_fork(struct task_struct *child) |
2997 | { | |
2998 | if (use_task_css_set_links) { | |
2999 | write_lock(&css_set_lock); | |
b12b533f | 3000 | task_lock(child); |
817929ec PM |
3001 | if (list_empty(&child->cg_list)) |
3002 | list_add(&child->cg_list, &child->cgroups->tasks); | |
b12b533f | 3003 | task_unlock(child); |
817929ec PM |
3004 | write_unlock(&css_set_lock); |
3005 | } | |
3006 | } | |
b4f48b63 PM |
3007 | /** |
3008 | * cgroup_exit - detach cgroup from exiting task | |
3009 | * @tsk: pointer to task_struct of exiting process | |
a043e3b2 | 3010 | * @run_callback: run exit callbacks? |
b4f48b63 PM |
3011 | * |
3012 | * Description: Detach cgroup from @tsk and release it. | |
3013 | * | |
3014 | * Note that cgroups marked notify_on_release force every task in | |
3015 | * them to take the global cgroup_mutex mutex when exiting. | |
3016 | * This could impact scaling on very large systems. Be reluctant to | |
3017 | * use notify_on_release cgroups where very high task exit scaling | |
3018 | * is required on large systems. | |
3019 | * | |
3020 | * the_top_cgroup_hack: | |
3021 | * | |
3022 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup). | |
3023 | * | |
3024 | * We call cgroup_exit() while the task is still competent to | |
3025 | * handle notify_on_release(), then leave the task attached to the | |
3026 | * root cgroup in each hierarchy for the remainder of its exit. | |
3027 | * | |
3028 | * To do this properly, we would increment the reference count on | |
3029 | * top_cgroup, and near the very end of the kernel/exit.c do_exit() | |
3030 | * code we would add a second cgroup function call, to drop that | |
3031 | * reference. This would just create an unnecessary hot spot on | |
3032 | * the top_cgroup reference count, to no avail. | |
3033 | * | |
3034 | * Normally, holding a reference to a cgroup without bumping its | |
3035 | * count is unsafe. The cgroup could go away, or someone could | |
3036 | * attach us to a different cgroup, decrementing the count on | |
3037 | * the first cgroup that we never incremented. But in this case, | |
3038 | * top_cgroup isn't going away, and either task has PF_EXITING set, | |
956db3ca CW |
3039 | * which wards off any cgroup_attach_task() attempts, or task is a failed |
3040 | * fork, never visible to cgroup_attach_task. | |
b4f48b63 PM |
3041 | */ |
3042 | void cgroup_exit(struct task_struct *tsk, int run_callbacks) | |
3043 | { | |
3044 | int i; | |
817929ec | 3045 | struct css_set *cg; |
b4f48b63 PM |
3046 | |
3047 | if (run_callbacks && need_forkexit_callback) { | |
3048 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
3049 | struct cgroup_subsys *ss = subsys[i]; | |
3050 | if (ss->exit) | |
3051 | ss->exit(ss, tsk); | |
3052 | } | |
3053 | } | |
817929ec PM |
3054 | |
3055 | /* | |
3056 | * Unlink from the css_set task list if necessary. | |
3057 | * Optimistically check cg_list before taking | |
3058 | * css_set_lock | |
3059 | */ | |
3060 | if (!list_empty(&tsk->cg_list)) { | |
3061 | write_lock(&css_set_lock); | |
3062 | if (!list_empty(&tsk->cg_list)) | |
3063 | list_del(&tsk->cg_list); | |
3064 | write_unlock(&css_set_lock); | |
3065 | } | |
3066 | ||
b4f48b63 PM |
3067 | /* Reassign the task to the init_css_set. */ |
3068 | task_lock(tsk); | |
817929ec PM |
3069 | cg = tsk->cgroups; |
3070 | tsk->cgroups = &init_css_set; | |
b4f48b63 | 3071 | task_unlock(tsk); |
817929ec | 3072 | if (cg) |
81a6a5cd | 3073 | put_css_set_taskexit(cg); |
b4f48b63 | 3074 | } |
697f4161 PM |
3075 | |
3076 | /** | |
a043e3b2 LZ |
3077 | * cgroup_clone - clone the cgroup the given subsystem is attached to |
3078 | * @tsk: the task to be moved | |
3079 | * @subsys: the given subsystem | |
e885dcde | 3080 | * @nodename: the name for the new cgroup |
a043e3b2 LZ |
3081 | * |
3082 | * Duplicate the current cgroup in the hierarchy that the given | |
3083 | * subsystem is attached to, and move this task into the new | |
3084 | * child. | |
697f4161 | 3085 | */ |
e885dcde SH |
3086 | int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys, |
3087 | char *nodename) | |
697f4161 PM |
3088 | { |
3089 | struct dentry *dentry; | |
3090 | int ret = 0; | |
697f4161 PM |
3091 | struct cgroup *parent, *child; |
3092 | struct inode *inode; | |
3093 | struct css_set *cg; | |
3094 | struct cgroupfs_root *root; | |
3095 | struct cgroup_subsys *ss; | |
3096 | ||
3097 | /* We shouldn't be called by an unregistered subsystem */ | |
3098 | BUG_ON(!subsys->active); | |
3099 | ||
3100 | /* First figure out what hierarchy and cgroup we're dealing | |
3101 | * with, and pin them so we can drop cgroup_mutex */ | |
3102 | mutex_lock(&cgroup_mutex); | |
3103 | again: | |
3104 | root = subsys->root; | |
3105 | if (root == &rootnode) { | |
697f4161 PM |
3106 | mutex_unlock(&cgroup_mutex); |
3107 | return 0; | |
3108 | } | |
697f4161 | 3109 | |
697f4161 | 3110 | /* Pin the hierarchy */ |
1404f065 | 3111 | if (!atomic_inc_not_zero(&root->sb->s_active)) { |
7b574b7b LZ |
3112 | /* We race with the final deactivate_super() */ |
3113 | mutex_unlock(&cgroup_mutex); | |
3114 | return 0; | |
3115 | } | |
697f4161 | 3116 | |
817929ec | 3117 | /* Keep the cgroup alive */ |
1404f065 LZ |
3118 | task_lock(tsk); |
3119 | parent = task_cgroup(tsk, subsys->subsys_id); | |
3120 | cg = tsk->cgroups; | |
817929ec | 3121 | get_css_set(cg); |
104cbd55 | 3122 | task_unlock(tsk); |
1404f065 | 3123 | |
697f4161 PM |
3124 | mutex_unlock(&cgroup_mutex); |
3125 | ||
3126 | /* Now do the VFS work to create a cgroup */ | |
3127 | inode = parent->dentry->d_inode; | |
3128 | ||
3129 | /* Hold the parent directory mutex across this operation to | |
3130 | * stop anyone else deleting the new cgroup */ | |
3131 | mutex_lock(&inode->i_mutex); | |
3132 | dentry = lookup_one_len(nodename, parent->dentry, strlen(nodename)); | |
3133 | if (IS_ERR(dentry)) { | |
3134 | printk(KERN_INFO | |
cfe36bde | 3135 | "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename, |
697f4161 PM |
3136 | PTR_ERR(dentry)); |
3137 | ret = PTR_ERR(dentry); | |
3138 | goto out_release; | |
3139 | } | |
3140 | ||
3141 | /* Create the cgroup directory, which also creates the cgroup */ | |
75139b82 | 3142 | ret = vfs_mkdir(inode, dentry, 0755); |
bd89aabc | 3143 | child = __d_cgrp(dentry); |
697f4161 PM |
3144 | dput(dentry); |
3145 | if (ret) { | |
3146 | printk(KERN_INFO | |
3147 | "Failed to create cgroup %s: %d\n", nodename, | |
3148 | ret); | |
3149 | goto out_release; | |
3150 | } | |
3151 | ||
697f4161 PM |
3152 | /* The cgroup now exists. Retake cgroup_mutex and check |
3153 | * that we're still in the same state that we thought we | |
3154 | * were. */ | |
3155 | mutex_lock(&cgroup_mutex); | |
3156 | if ((root != subsys->root) || | |
3157 | (parent != task_cgroup(tsk, subsys->subsys_id))) { | |
3158 | /* Aargh, we raced ... */ | |
3159 | mutex_unlock(&inode->i_mutex); | |
817929ec | 3160 | put_css_set(cg); |
697f4161 | 3161 | |
1404f065 | 3162 | deactivate_super(root->sb); |
697f4161 PM |
3163 | /* The cgroup is still accessible in the VFS, but |
3164 | * we're not going to try to rmdir() it at this | |
3165 | * point. */ | |
3166 | printk(KERN_INFO | |
3167 | "Race in cgroup_clone() - leaking cgroup %s\n", | |
3168 | nodename); | |
3169 | goto again; | |
3170 | } | |
3171 | ||
3172 | /* do any required auto-setup */ | |
3173 | for_each_subsys(root, ss) { | |
3174 | if (ss->post_clone) | |
3175 | ss->post_clone(ss, child); | |
3176 | } | |
3177 | ||
3178 | /* All seems fine. Finish by moving the task into the new cgroup */ | |
956db3ca | 3179 | ret = cgroup_attach_task(child, tsk); |
697f4161 PM |
3180 | mutex_unlock(&cgroup_mutex); |
3181 | ||
3182 | out_release: | |
3183 | mutex_unlock(&inode->i_mutex); | |
81a6a5cd PM |
3184 | |
3185 | mutex_lock(&cgroup_mutex); | |
817929ec | 3186 | put_css_set(cg); |
81a6a5cd | 3187 | mutex_unlock(&cgroup_mutex); |
1404f065 | 3188 | deactivate_super(root->sb); |
697f4161 PM |
3189 | return ret; |
3190 | } | |
3191 | ||
a043e3b2 | 3192 | /** |
313e924c | 3193 | * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp |
a043e3b2 | 3194 | * @cgrp: the cgroup in question |
313e924c | 3195 | * @task: the task in question |
a043e3b2 | 3196 | * |
313e924c GN |
3197 | * See if @cgrp is a descendant of @task's cgroup in the appropriate |
3198 | * hierarchy. | |
697f4161 PM |
3199 | * |
3200 | * If we are sending in dummytop, then presumably we are creating | |
3201 | * the top cgroup in the subsystem. | |
3202 | * | |
3203 | * Called only by the ns (nsproxy) cgroup. | |
3204 | */ | |
313e924c | 3205 | int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task) |
697f4161 PM |
3206 | { |
3207 | int ret; | |
3208 | struct cgroup *target; | |
3209 | int subsys_id; | |
3210 | ||
bd89aabc | 3211 | if (cgrp == dummytop) |
697f4161 PM |
3212 | return 1; |
3213 | ||
bd89aabc | 3214 | get_first_subsys(cgrp, NULL, &subsys_id); |
313e924c | 3215 | target = task_cgroup(task, subsys_id); |
bd89aabc PM |
3216 | while (cgrp != target && cgrp!= cgrp->top_cgroup) |
3217 | cgrp = cgrp->parent; | |
3218 | ret = (cgrp == target); | |
697f4161 PM |
3219 | return ret; |
3220 | } | |
81a6a5cd | 3221 | |
bd89aabc | 3222 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd PM |
3223 | { |
3224 | /* All of these checks rely on RCU to keep the cgroup | |
3225 | * structure alive */ | |
bd89aabc PM |
3226 | if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count) |
3227 | && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) { | |
81a6a5cd PM |
3228 | /* Control Group is currently removeable. If it's not |
3229 | * already queued for a userspace notification, queue | |
3230 | * it now */ | |
3231 | int need_schedule_work = 0; | |
3232 | spin_lock(&release_list_lock); | |
bd89aabc PM |
3233 | if (!cgroup_is_removed(cgrp) && |
3234 | list_empty(&cgrp->release_list)) { | |
3235 | list_add(&cgrp->release_list, &release_list); | |
81a6a5cd PM |
3236 | need_schedule_work = 1; |
3237 | } | |
3238 | spin_unlock(&release_list_lock); | |
3239 | if (need_schedule_work) | |
3240 | schedule_work(&release_agent_work); | |
3241 | } | |
3242 | } | |
3243 | ||
3244 | void __css_put(struct cgroup_subsys_state *css) | |
3245 | { | |
bd89aabc | 3246 | struct cgroup *cgrp = css->cgroup; |
81a6a5cd | 3247 | rcu_read_lock(); |
ec64f515 KH |
3248 | if (atomic_dec_return(&css->refcnt) == 1) { |
3249 | if (notify_on_release(cgrp)) { | |
3250 | set_bit(CGRP_RELEASABLE, &cgrp->flags); | |
3251 | check_for_release(cgrp); | |
3252 | } | |
3253 | cgroup_wakeup_rmdir_waiters(cgrp); | |
81a6a5cd PM |
3254 | } |
3255 | rcu_read_unlock(); | |
3256 | } | |
3257 | ||
3258 | /* | |
3259 | * Notify userspace when a cgroup is released, by running the | |
3260 | * configured release agent with the name of the cgroup (path | |
3261 | * relative to the root of cgroup file system) as the argument. | |
3262 | * | |
3263 | * Most likely, this user command will try to rmdir this cgroup. | |
3264 | * | |
3265 | * This races with the possibility that some other task will be | |
3266 | * attached to this cgroup before it is removed, or that some other | |
3267 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
3268 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
3269 | * unused, and this cgroup will be reprieved from its death sentence, | |
3270 | * to continue to serve a useful existence. Next time it's released, | |
3271 | * we will get notified again, if it still has 'notify_on_release' set. | |
3272 | * | |
3273 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
3274 | * means only wait until the task is successfully execve()'d. The | |
3275 | * separate release agent task is forked by call_usermodehelper(), | |
3276 | * then control in this thread returns here, without waiting for the | |
3277 | * release agent task. We don't bother to wait because the caller of | |
3278 | * this routine has no use for the exit status of the release agent | |
3279 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 3280 | */ |
81a6a5cd PM |
3281 | static void cgroup_release_agent(struct work_struct *work) |
3282 | { | |
3283 | BUG_ON(work != &release_agent_work); | |
3284 | mutex_lock(&cgroup_mutex); | |
3285 | spin_lock(&release_list_lock); | |
3286 | while (!list_empty(&release_list)) { | |
3287 | char *argv[3], *envp[3]; | |
3288 | int i; | |
e788e066 | 3289 | char *pathbuf = NULL, *agentbuf = NULL; |
bd89aabc | 3290 | struct cgroup *cgrp = list_entry(release_list.next, |
81a6a5cd PM |
3291 | struct cgroup, |
3292 | release_list); | |
bd89aabc | 3293 | list_del_init(&cgrp->release_list); |
81a6a5cd PM |
3294 | spin_unlock(&release_list_lock); |
3295 | pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
e788e066 PM |
3296 | if (!pathbuf) |
3297 | goto continue_free; | |
3298 | if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) | |
3299 | goto continue_free; | |
3300 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
3301 | if (!agentbuf) | |
3302 | goto continue_free; | |
81a6a5cd PM |
3303 | |
3304 | i = 0; | |
e788e066 PM |
3305 | argv[i++] = agentbuf; |
3306 | argv[i++] = pathbuf; | |
81a6a5cd PM |
3307 | argv[i] = NULL; |
3308 | ||
3309 | i = 0; | |
3310 | /* minimal command environment */ | |
3311 | envp[i++] = "HOME=/"; | |
3312 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
3313 | envp[i] = NULL; | |
3314 | ||
3315 | /* Drop the lock while we invoke the usermode helper, | |
3316 | * since the exec could involve hitting disk and hence | |
3317 | * be a slow process */ | |
3318 | mutex_unlock(&cgroup_mutex); | |
3319 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
81a6a5cd | 3320 | mutex_lock(&cgroup_mutex); |
e788e066 PM |
3321 | continue_free: |
3322 | kfree(pathbuf); | |
3323 | kfree(agentbuf); | |
81a6a5cd PM |
3324 | spin_lock(&release_list_lock); |
3325 | } | |
3326 | spin_unlock(&release_list_lock); | |
3327 | mutex_unlock(&cgroup_mutex); | |
3328 | } | |
8bab8dde PM |
3329 | |
3330 | static int __init cgroup_disable(char *str) | |
3331 | { | |
3332 | int i; | |
3333 | char *token; | |
3334 | ||
3335 | while ((token = strsep(&str, ",")) != NULL) { | |
3336 | if (!*token) | |
3337 | continue; | |
3338 | ||
3339 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
3340 | struct cgroup_subsys *ss = subsys[i]; | |
3341 | ||
3342 | if (!strcmp(token, ss->name)) { | |
3343 | ss->disabled = 1; | |
3344 | printk(KERN_INFO "Disabling %s control group" | |
3345 | " subsystem\n", ss->name); | |
3346 | break; | |
3347 | } | |
3348 | } | |
3349 | } | |
3350 | return 1; | |
3351 | } | |
3352 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 KH |
3353 | |
3354 | /* | |
3355 | * Functons for CSS ID. | |
3356 | */ | |
3357 | ||
3358 | /* | |
3359 | *To get ID other than 0, this should be called when !cgroup_is_removed(). | |
3360 | */ | |
3361 | unsigned short css_id(struct cgroup_subsys_state *css) | |
3362 | { | |
3363 | struct css_id *cssid = rcu_dereference(css->id); | |
3364 | ||
3365 | if (cssid) | |
3366 | return cssid->id; | |
3367 | return 0; | |
3368 | } | |
3369 | ||
3370 | unsigned short css_depth(struct cgroup_subsys_state *css) | |
3371 | { | |
3372 | struct css_id *cssid = rcu_dereference(css->id); | |
3373 | ||
3374 | if (cssid) | |
3375 | return cssid->depth; | |
3376 | return 0; | |
3377 | } | |
3378 | ||
3379 | bool css_is_ancestor(struct cgroup_subsys_state *child, | |
3380 | struct cgroup_subsys_state *root) | |
3381 | { | |
3382 | struct css_id *child_id = rcu_dereference(child->id); | |
3383 | struct css_id *root_id = rcu_dereference(root->id); | |
3384 | ||
3385 | if (!child_id || !root_id || (child_id->depth < root_id->depth)) | |
3386 | return false; | |
3387 | return child_id->stack[root_id->depth] == root_id->id; | |
3388 | } | |
3389 | ||
3390 | static void __free_css_id_cb(struct rcu_head *head) | |
3391 | { | |
3392 | struct css_id *id; | |
3393 | ||
3394 | id = container_of(head, struct css_id, rcu_head); | |
3395 | kfree(id); | |
3396 | } | |
3397 | ||
3398 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) | |
3399 | { | |
3400 | struct css_id *id = css->id; | |
3401 | /* When this is called before css_id initialization, id can be NULL */ | |
3402 | if (!id) | |
3403 | return; | |
3404 | ||
3405 | BUG_ON(!ss->use_id); | |
3406 | ||
3407 | rcu_assign_pointer(id->css, NULL); | |
3408 | rcu_assign_pointer(css->id, NULL); | |
3409 | spin_lock(&ss->id_lock); | |
3410 | idr_remove(&ss->idr, id->id); | |
3411 | spin_unlock(&ss->id_lock); | |
3412 | call_rcu(&id->rcu_head, __free_css_id_cb); | |
3413 | } | |
3414 | ||
3415 | /* | |
3416 | * This is called by init or create(). Then, calls to this function are | |
3417 | * always serialized (By cgroup_mutex() at create()). | |
3418 | */ | |
3419 | ||
3420 | static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) | |
3421 | { | |
3422 | struct css_id *newid; | |
3423 | int myid, error, size; | |
3424 | ||
3425 | BUG_ON(!ss->use_id); | |
3426 | ||
3427 | size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); | |
3428 | newid = kzalloc(size, GFP_KERNEL); | |
3429 | if (!newid) | |
3430 | return ERR_PTR(-ENOMEM); | |
3431 | /* get id */ | |
3432 | if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) { | |
3433 | error = -ENOMEM; | |
3434 | goto err_out; | |
3435 | } | |
3436 | spin_lock(&ss->id_lock); | |
3437 | /* Don't use 0. allocates an ID of 1-65535 */ | |
3438 | error = idr_get_new_above(&ss->idr, newid, 1, &myid); | |
3439 | spin_unlock(&ss->id_lock); | |
3440 | ||
3441 | /* Returns error when there are no free spaces for new ID.*/ | |
3442 | if (error) { | |
3443 | error = -ENOSPC; | |
3444 | goto err_out; | |
3445 | } | |
3446 | if (myid > CSS_ID_MAX) | |
3447 | goto remove_idr; | |
3448 | ||
3449 | newid->id = myid; | |
3450 | newid->depth = depth; | |
3451 | return newid; | |
3452 | remove_idr: | |
3453 | error = -ENOSPC; | |
3454 | spin_lock(&ss->id_lock); | |
3455 | idr_remove(&ss->idr, myid); | |
3456 | spin_unlock(&ss->id_lock); | |
3457 | err_out: | |
3458 | kfree(newid); | |
3459 | return ERR_PTR(error); | |
3460 | ||
3461 | } | |
3462 | ||
3463 | static int __init cgroup_subsys_init_idr(struct cgroup_subsys *ss) | |
3464 | { | |
3465 | struct css_id *newid; | |
3466 | struct cgroup_subsys_state *rootcss; | |
3467 | ||
3468 | spin_lock_init(&ss->id_lock); | |
3469 | idr_init(&ss->idr); | |
3470 | ||
3471 | rootcss = init_css_set.subsys[ss->subsys_id]; | |
3472 | newid = get_new_cssid(ss, 0); | |
3473 | if (IS_ERR(newid)) | |
3474 | return PTR_ERR(newid); | |
3475 | ||
3476 | newid->stack[0] = newid->id; | |
3477 | newid->css = rootcss; | |
3478 | rootcss->id = newid; | |
3479 | return 0; | |
3480 | } | |
3481 | ||
3482 | static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, | |
3483 | struct cgroup *child) | |
3484 | { | |
3485 | int subsys_id, i, depth = 0; | |
3486 | struct cgroup_subsys_state *parent_css, *child_css; | |
3487 | struct css_id *child_id, *parent_id = NULL; | |
3488 | ||
3489 | subsys_id = ss->subsys_id; | |
3490 | parent_css = parent->subsys[subsys_id]; | |
3491 | child_css = child->subsys[subsys_id]; | |
3492 | depth = css_depth(parent_css) + 1; | |
3493 | parent_id = parent_css->id; | |
3494 | ||
3495 | child_id = get_new_cssid(ss, depth); | |
3496 | if (IS_ERR(child_id)) | |
3497 | return PTR_ERR(child_id); | |
3498 | ||
3499 | for (i = 0; i < depth; i++) | |
3500 | child_id->stack[i] = parent_id->stack[i]; | |
3501 | child_id->stack[depth] = child_id->id; | |
3502 | /* | |
3503 | * child_id->css pointer will be set after this cgroup is available | |
3504 | * see cgroup_populate_dir() | |
3505 | */ | |
3506 | rcu_assign_pointer(child_css->id, child_id); | |
3507 | ||
3508 | return 0; | |
3509 | } | |
3510 | ||
3511 | /** | |
3512 | * css_lookup - lookup css by id | |
3513 | * @ss: cgroup subsys to be looked into. | |
3514 | * @id: the id | |
3515 | * | |
3516 | * Returns pointer to cgroup_subsys_state if there is valid one with id. | |
3517 | * NULL if not. Should be called under rcu_read_lock() | |
3518 | */ | |
3519 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) | |
3520 | { | |
3521 | struct css_id *cssid = NULL; | |
3522 | ||
3523 | BUG_ON(!ss->use_id); | |
3524 | cssid = idr_find(&ss->idr, id); | |
3525 | ||
3526 | if (unlikely(!cssid)) | |
3527 | return NULL; | |
3528 | ||
3529 | return rcu_dereference(cssid->css); | |
3530 | } | |
3531 | ||
3532 | /** | |
3533 | * css_get_next - lookup next cgroup under specified hierarchy. | |
3534 | * @ss: pointer to subsystem | |
3535 | * @id: current position of iteration. | |
3536 | * @root: pointer to css. search tree under this. | |
3537 | * @foundid: position of found object. | |
3538 | * | |
3539 | * Search next css under the specified hierarchy of rootid. Calling under | |
3540 | * rcu_read_lock() is necessary. Returns NULL if it reaches the end. | |
3541 | */ | |
3542 | struct cgroup_subsys_state * | |
3543 | css_get_next(struct cgroup_subsys *ss, int id, | |
3544 | struct cgroup_subsys_state *root, int *foundid) | |
3545 | { | |
3546 | struct cgroup_subsys_state *ret = NULL; | |
3547 | struct css_id *tmp; | |
3548 | int tmpid; | |
3549 | int rootid = css_id(root); | |
3550 | int depth = css_depth(root); | |
3551 | ||
3552 | if (!rootid) | |
3553 | return NULL; | |
3554 | ||
3555 | BUG_ON(!ss->use_id); | |
3556 | /* fill start point for scan */ | |
3557 | tmpid = id; | |
3558 | while (1) { | |
3559 | /* | |
3560 | * scan next entry from bitmap(tree), tmpid is updated after | |
3561 | * idr_get_next(). | |
3562 | */ | |
3563 | spin_lock(&ss->id_lock); | |
3564 | tmp = idr_get_next(&ss->idr, &tmpid); | |
3565 | spin_unlock(&ss->id_lock); | |
3566 | ||
3567 | if (!tmp) | |
3568 | break; | |
3569 | if (tmp->depth >= depth && tmp->stack[depth] == rootid) { | |
3570 | ret = rcu_dereference(tmp->css); | |
3571 | if (ret) { | |
3572 | *foundid = tmpid; | |
3573 | break; | |
3574 | } | |
3575 | } | |
3576 | /* continue to scan from next id */ | |
3577 | tmpid = tmpid + 1; | |
3578 | } | |
3579 | return ret; | |
3580 | } | |
3581 |