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1 | /* |
2 | * Common Block IO controller cgroup interface |
3 | * |
4 | * Based on ideas and code from CFQ, CFS and BFQ: |
5 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> |
6 | * |
7 | * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> |
8 | * Paolo Valente <paolo.valente@unimore.it> |
9 | * |
10 | * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com> |
11 | * Nauman Rafique <nauman@google.com> |
12 | */ |
13 | #include <linux/ioprio.h> |
14 | #include <linux/kdev_t.h> |
15 | #include <linux/module.h> |
16 | #include <linux/err.h> |
17 | #include <linux/blkdev.h> |
18 | #include <linux/slab.h> |
19 | #include <linux/genhd.h> |
20 | #include <linux/delay.h> |
21 | #include <linux/atomic.h> |
22 | #include "blk-cgroup.h" |
23 | #include "blk.h" |
24 | |
25 | #define MAX_KEY_LEN 100 |
26 | |
27 | static DEFINE_MUTEX(blkcg_pol_mutex); |
28 | |
29 | struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT, |
30 | .cfq_leaf_weight = 2 * CFQ_WEIGHT_DEFAULT, }; |
31 | EXPORT_SYMBOL_GPL(blkcg_root); |
32 | |
33 | static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; |
34 | |
35 | static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, |
36 | struct request_queue *q, bool update_hint); |
37 | |
38 | /** |
39 | * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants |
40 | * @d_blkg: loop cursor pointing to the current descendant |
41 | * @pos_cgrp: used for iteration |
42 | * @p_blkg: target blkg to walk descendants of |
43 | * |
44 | * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU |
45 | * read locked. If called under either blkcg or queue lock, the iteration |
46 | * is guaranteed to include all and only online blkgs. The caller may |
47 | * update @pos_cgrp by calling cgroup_rightmost_descendant() to skip |
48 | * subtree. |
49 | */ |
50 | #define blkg_for_each_descendant_pre(d_blkg, pos_cgrp, p_blkg) \ |
51 | cgroup_for_each_descendant_pre((pos_cgrp), (p_blkg)->blkcg->css.cgroup) \ |
52 | if (((d_blkg) = __blkg_lookup(cgroup_to_blkcg(pos_cgrp), \ |
53 | (p_blkg)->q, false))) |
54 | |
55 | static bool blkcg_policy_enabled(struct request_queue *q, |
56 | const struct blkcg_policy *pol) |
57 | { |
58 | return pol && test_bit(pol->plid, q->blkcg_pols); |
59 | } |
60 | |
61 | /** |
62 | * blkg_free - free a blkg |
63 | * @blkg: blkg to free |
64 | * |
65 | * Free @blkg which may be partially allocated. |
66 | */ |
67 | static void blkg_free(struct blkcg_gq *blkg) |
68 | { |
69 | int i; |
70 | |
71 | if (!blkg) |
72 | return; |
73 | |
74 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
75 | struct blkcg_policy *pol = blkcg_policy[i]; |
76 | struct blkg_policy_data *pd = blkg->pd[i]; |
77 | |
78 | if (!pd) |
79 | continue; |
80 | |
81 | if (pol && pol->pd_exit_fn) |
82 | pol->pd_exit_fn(blkg); |
83 | |
84 | kfree(pd); |
85 | } |
86 | |
87 | blk_exit_rl(&blkg->rl); |
88 | kfree(blkg); |
89 | } |
90 | |
91 | /** |
92 | * blkg_alloc - allocate a blkg |
93 | * @blkcg: block cgroup the new blkg is associated with |
94 | * @q: request_queue the new blkg is associated with |
95 | * @gfp_mask: allocation mask to use |
96 | * |
97 | * Allocate a new blkg assocating @blkcg and @q. |
98 | */ |
99 | static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, |
100 | gfp_t gfp_mask) |
101 | { |
102 | struct blkcg_gq *blkg; |
103 | int i; |
104 | |
105 | /* alloc and init base part */ |
106 | blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); |
107 | if (!blkg) |
108 | return NULL; |
109 | |
110 | blkg->q = q; |
111 | INIT_LIST_HEAD(&blkg->q_node); |
112 | blkg->blkcg = blkcg; |
113 | blkg->refcnt = 1; |
114 | |
115 | /* root blkg uses @q->root_rl, init rl only for !root blkgs */ |
116 | if (blkcg != &blkcg_root) { |
117 | if (blk_init_rl(&blkg->rl, q, gfp_mask)) |
118 | goto err_free; |
119 | blkg->rl.blkg = blkg; |
120 | } |
121 | |
122 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
123 | struct blkcg_policy *pol = blkcg_policy[i]; |
124 | struct blkg_policy_data *pd; |
125 | |
126 | if (!blkcg_policy_enabled(q, pol)) |
127 | continue; |
128 | |
129 | /* alloc per-policy data and attach it to blkg */ |
130 | pd = kzalloc_node(pol->pd_size, gfp_mask, q->node); |
131 | if (!pd) |
132 | goto err_free; |
133 | |
134 | blkg->pd[i] = pd; |
135 | pd->blkg = blkg; |
136 | pd->plid = i; |
137 | |
138 | /* invoke per-policy init */ |
139 | if (pol->pd_init_fn) |
140 | pol->pd_init_fn(blkg); |
141 | } |
142 | |
143 | return blkg; |
144 | |
145 | err_free: |
146 | blkg_free(blkg); |
147 | return NULL; |
148 | } |
149 | |
150 | /** |
151 | * __blkg_lookup - internal version of blkg_lookup() |
152 | * @blkcg: blkcg of interest |
153 | * @q: request_queue of interest |
154 | * @update_hint: whether to update lookup hint with the result or not |
155 | * |
156 | * This is internal version and shouldn't be used by policy |
157 | * implementations. Looks up blkgs for the @blkcg - @q pair regardless of |
158 | * @q's bypass state. If @update_hint is %true, the caller should be |
159 | * holding @q->queue_lock and lookup hint is updated on success. |
160 | */ |
161 | static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, |
162 | struct request_queue *q, bool update_hint) |
163 | { |
164 | struct blkcg_gq *blkg; |
165 | |
166 | blkg = rcu_dereference(blkcg->blkg_hint); |
167 | if (blkg && blkg->q == q) |
168 | return blkg; |
169 | |
170 | /* |
171 | * Hint didn't match. Look up from the radix tree. Note that the |
172 | * hint can only be updated under queue_lock as otherwise @blkg |
173 | * could have already been removed from blkg_tree. The caller is |
174 | * responsible for grabbing queue_lock if @update_hint. |
175 | */ |
176 | blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); |
177 | if (blkg && blkg->q == q) { |
178 | if (update_hint) { |
179 | lockdep_assert_held(q->queue_lock); |
180 | rcu_assign_pointer(blkcg->blkg_hint, blkg); |
181 | } |
182 | return blkg; |
183 | } |
184 | |
185 | return NULL; |
186 | } |
187 | |
188 | /** |
189 | * blkg_lookup - lookup blkg for the specified blkcg - q pair |
190 | * @blkcg: blkcg of interest |
191 | * @q: request_queue of interest |
192 | * |
193 | * Lookup blkg for the @blkcg - @q pair. This function should be called |
194 | * under RCU read lock and is guaranteed to return %NULL if @q is bypassing |
195 | * - see blk_queue_bypass_start() for details. |
196 | */ |
197 | struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q) |
198 | { |
199 | WARN_ON_ONCE(!rcu_read_lock_held()); |
200 | |
201 | if (unlikely(blk_queue_bypass(q))) |
202 | return NULL; |
203 | return __blkg_lookup(blkcg, q, false); |
204 | } |
205 | EXPORT_SYMBOL_GPL(blkg_lookup); |
206 | |
207 | /* |
208 | * If @new_blkg is %NULL, this function tries to allocate a new one as |
209 | * necessary using %GFP_ATOMIC. @new_blkg is always consumed on return. |
210 | */ |
211 | static struct blkcg_gq *blkg_create(struct blkcg *blkcg, |
212 | struct request_queue *q, |
213 | struct blkcg_gq *new_blkg) |
214 | { |
215 | struct blkcg_gq *blkg; |
216 | int i, ret; |
217 | |
218 | WARN_ON_ONCE(!rcu_read_lock_held()); |
219 | lockdep_assert_held(q->queue_lock); |
220 | |
221 | /* blkg holds a reference to blkcg */ |
222 | if (!css_tryget(&blkcg->css)) { |
223 | ret = -EINVAL; |
224 | goto err_free_blkg; |
225 | } |
226 | |
227 | /* allocate */ |
228 | if (!new_blkg) { |
229 | new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC); |
230 | if (unlikely(!new_blkg)) { |
231 | ret = -ENOMEM; |
232 | goto err_put_css; |
233 | } |
234 | } |
235 | blkg = new_blkg; |
236 | |
237 | /* link parent and insert */ |
238 | if (blkcg_parent(blkcg)) { |
239 | blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); |
240 | if (WARN_ON_ONCE(!blkg->parent)) { |
241 | blkg = ERR_PTR(-EINVAL); |
242 | goto err_put_css; |
243 | } |
244 | blkg_get(blkg->parent); |
245 | } |
246 | |
247 | spin_lock(&blkcg->lock); |
248 | ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); |
249 | if (likely(!ret)) { |
250 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); |
251 | list_add(&blkg->q_node, &q->blkg_list); |
252 | |
253 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
254 | struct blkcg_policy *pol = blkcg_policy[i]; |
255 | |
256 | if (blkg->pd[i] && pol->pd_online_fn) |
257 | pol->pd_online_fn(blkg); |
258 | } |
259 | } |
260 | blkg->online = true; |
261 | spin_unlock(&blkcg->lock); |
262 | |
263 | if (!ret) |
264 | return blkg; |
265 | |
266 | /* @blkg failed fully initialized, use the usual release path */ |
267 | blkg_put(blkg); |
268 | return ERR_PTR(ret); |
269 | |
270 | err_put_css: |
271 | css_put(&blkcg->css); |
272 | err_free_blkg: |
273 | blkg_free(new_blkg); |
274 | return ERR_PTR(ret); |
275 | } |
276 | |
277 | /** |
278 | * blkg_lookup_create - lookup blkg, try to create one if not there |
279 | * @blkcg: blkcg of interest |
280 | * @q: request_queue of interest |
281 | * |
282 | * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to |
283 | * create one. blkg creation is performed recursively from blkcg_root such |
284 | * that all non-root blkg's have access to the parent blkg. This function |
285 | * should be called under RCU read lock and @q->queue_lock. |
286 | * |
287 | * Returns pointer to the looked up or created blkg on success, ERR_PTR() |
288 | * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not |
289 | * dead and bypassing, returns ERR_PTR(-EBUSY). |
290 | */ |
291 | struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, |
292 | struct request_queue *q) |
293 | { |
294 | struct blkcg_gq *blkg; |
295 | |
296 | WARN_ON_ONCE(!rcu_read_lock_held()); |
297 | lockdep_assert_held(q->queue_lock); |
298 | |
299 | /* |
300 | * This could be the first entry point of blkcg implementation and |
301 | * we shouldn't allow anything to go through for a bypassing queue. |
302 | */ |
303 | if (unlikely(blk_queue_bypass(q))) |
304 | return ERR_PTR(blk_queue_dying(q) ? -EINVAL : -EBUSY); |
305 | |
306 | blkg = __blkg_lookup(blkcg, q, true); |
307 | if (blkg) |
308 | return blkg; |
309 | |
310 | /* |
311 | * Create blkgs walking down from blkcg_root to @blkcg, so that all |
312 | * non-root blkgs have access to their parents. |
313 | */ |
314 | while (true) { |
315 | struct blkcg *pos = blkcg; |
316 | struct blkcg *parent = blkcg_parent(blkcg); |
317 | |
318 | while (parent && !__blkg_lookup(parent, q, false)) { |
319 | pos = parent; |
320 | parent = blkcg_parent(parent); |
321 | } |
322 | |
323 | blkg = blkg_create(pos, q, NULL); |
324 | if (pos == blkcg || IS_ERR(blkg)) |
325 | return blkg; |
326 | } |
327 | } |
328 | EXPORT_SYMBOL_GPL(blkg_lookup_create); |
329 | |
330 | static void blkg_destroy(struct blkcg_gq *blkg) |
331 | { |
332 | struct blkcg *blkcg = blkg->blkcg; |
333 | int i; |
334 | |
335 | lockdep_assert_held(blkg->q->queue_lock); |
336 | lockdep_assert_held(&blkcg->lock); |
337 | |
338 | /* Something wrong if we are trying to remove same group twice */ |
339 | WARN_ON_ONCE(list_empty(&blkg->q_node)); |
340 | WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); |
341 | |
342 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
343 | struct blkcg_policy *pol = blkcg_policy[i]; |
344 | |
345 | if (blkg->pd[i] && pol->pd_offline_fn) |
346 | pol->pd_offline_fn(blkg); |
347 | } |
348 | blkg->online = false; |
349 | |
350 | radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); |
351 | list_del_init(&blkg->q_node); |
352 | hlist_del_init_rcu(&blkg->blkcg_node); |
353 | |
354 | /* |
355 | * Both setting lookup hint to and clearing it from @blkg are done |
356 | * under queue_lock. If it's not pointing to @blkg now, it never |
357 | * will. Hint assignment itself can race safely. |
358 | */ |
359 | if (rcu_dereference_raw(blkcg->blkg_hint) == blkg) |
360 | rcu_assign_pointer(blkcg->blkg_hint, NULL); |
361 | |
362 | /* |
363 | * Put the reference taken at the time of creation so that when all |
364 | * queues are gone, group can be destroyed. |
365 | */ |
366 | blkg_put(blkg); |
367 | } |
368 | |
369 | /** |
370 | * blkg_destroy_all - destroy all blkgs associated with a request_queue |
371 | * @q: request_queue of interest |
372 | * |
373 | * Destroy all blkgs associated with @q. |
374 | */ |
375 | static void blkg_destroy_all(struct request_queue *q) |
376 | { |
377 | struct blkcg_gq *blkg, *n; |
378 | |
379 | lockdep_assert_held(q->queue_lock); |
380 | |
381 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { |
382 | struct blkcg *blkcg = blkg->blkcg; |
383 | |
384 | spin_lock(&blkcg->lock); |
385 | blkg_destroy(blkg); |
386 | spin_unlock(&blkcg->lock); |
387 | } |
388 | |
389 | /* |
390 | * root blkg is destroyed. Just clear the pointer since |
391 | * root_rl does not take reference on root blkg. |
392 | */ |
393 | q->root_blkg = NULL; |
394 | q->root_rl.blkg = NULL; |
395 | } |
396 | |
397 | static void blkg_rcu_free(struct rcu_head *rcu_head) |
398 | { |
399 | blkg_free(container_of(rcu_head, struct blkcg_gq, rcu_head)); |
400 | } |
401 | |
402 | void __blkg_release(struct blkcg_gq *blkg) |
403 | { |
404 | /* release the blkcg and parent blkg refs this blkg has been holding */ |
405 | css_put(&blkg->blkcg->css); |
406 | if (blkg->parent) |
407 | blkg_put(blkg->parent); |
408 | |
409 | /* |
410 | * A group is freed in rcu manner. But having an rcu lock does not |
411 | * mean that one can access all the fields of blkg and assume these |
412 | * are valid. For example, don't try to follow throtl_data and |
413 | * request queue links. |
414 | * |
415 | * Having a reference to blkg under an rcu allows acess to only |
416 | * values local to groups like group stats and group rate limits |
417 | */ |
418 | call_rcu(&blkg->rcu_head, blkg_rcu_free); |
419 | } |
420 | EXPORT_SYMBOL_GPL(__blkg_release); |
421 | |
422 | /* |
423 | * The next function used by blk_queue_for_each_rl(). It's a bit tricky |
424 | * because the root blkg uses @q->root_rl instead of its own rl. |
425 | */ |
426 | struct request_list *__blk_queue_next_rl(struct request_list *rl, |
427 | struct request_queue *q) |
428 | { |
429 | struct list_head *ent; |
430 | struct blkcg_gq *blkg; |
431 | |
432 | /* |
433 | * Determine the current blkg list_head. The first entry is |
434 | * root_rl which is off @q->blkg_list and mapped to the head. |
435 | */ |
436 | if (rl == &q->root_rl) { |
437 | ent = &q->blkg_list; |
438 | /* There are no more block groups, hence no request lists */ |
439 | if (list_empty(ent)) |
440 | return NULL; |
441 | } else { |
442 | blkg = container_of(rl, struct blkcg_gq, rl); |
443 | ent = &blkg->q_node; |
444 | } |
445 | |
446 | /* walk to the next list_head, skip root blkcg */ |
447 | ent = ent->next; |
448 | if (ent == &q->root_blkg->q_node) |
449 | ent = ent->next; |
450 | if (ent == &q->blkg_list) |
451 | return NULL; |
452 | |
453 | blkg = container_of(ent, struct blkcg_gq, q_node); |
454 | return &blkg->rl; |
455 | } |
456 | |
457 | static int blkcg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, |
458 | u64 val) |
459 | { |
460 | struct blkcg *blkcg = cgroup_to_blkcg(cgroup); |
461 | struct blkcg_gq *blkg; |
462 | int i; |
463 | |
464 | mutex_lock(&blkcg_pol_mutex); |
465 | spin_lock_irq(&blkcg->lock); |
466 | |
467 | /* |
468 | * Note that stat reset is racy - it doesn't synchronize against |
469 | * stat updates. This is a debug feature which shouldn't exist |
470 | * anyway. If you get hit by a race, retry. |
471 | */ |
472 | hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { |
473 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
474 | struct blkcg_policy *pol = blkcg_policy[i]; |
475 | |
476 | if (blkcg_policy_enabled(blkg->q, pol) && |
477 | pol->pd_reset_stats_fn) |
478 | pol->pd_reset_stats_fn(blkg); |
479 | } |
480 | } |
481 | |
482 | spin_unlock_irq(&blkcg->lock); |
483 | mutex_unlock(&blkcg_pol_mutex); |
484 | return 0; |
485 | } |
486 | |
487 | static const char *blkg_dev_name(struct blkcg_gq *blkg) |
488 | { |
489 | /* some drivers (floppy) instantiate a queue w/o disk registered */ |
490 | if (blkg->q->backing_dev_info.dev) |
491 | return dev_name(blkg->q->backing_dev_info.dev); |
492 | return NULL; |
493 | } |
494 | |
495 | /** |
496 | * blkcg_print_blkgs - helper for printing per-blkg data |
497 | * @sf: seq_file to print to |
498 | * @blkcg: blkcg of interest |
499 | * @prfill: fill function to print out a blkg |
500 | * @pol: policy in question |
501 | * @data: data to be passed to @prfill |
502 | * @show_total: to print out sum of prfill return values or not |
503 | * |
504 | * This function invokes @prfill on each blkg of @blkcg if pd for the |
505 | * policy specified by @pol exists. @prfill is invoked with @sf, the |
506 | * policy data and @data and the matching queue lock held. If @show_total |
507 | * is %true, the sum of the return values from @prfill is printed with |
508 | * "Total" label at the end. |
509 | * |
510 | * This is to be used to construct print functions for |
511 | * cftype->read_seq_string method. |
512 | */ |
513 | void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, |
514 | u64 (*prfill)(struct seq_file *, |
515 | struct blkg_policy_data *, int), |
516 | const struct blkcg_policy *pol, int data, |
517 | bool show_total) |
518 | { |
519 | struct blkcg_gq *blkg; |
520 | u64 total = 0; |
521 | |
522 | rcu_read_lock(); |
523 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
524 | spin_lock_irq(blkg->q->queue_lock); |
525 | if (blkcg_policy_enabled(blkg->q, pol)) |
526 | total += prfill(sf, blkg->pd[pol->plid], data); |
527 | spin_unlock_irq(blkg->q->queue_lock); |
528 | } |
529 | rcu_read_unlock(); |
530 | |
531 | if (show_total) |
532 | seq_printf(sf, "Total %llu\n", (unsigned long long)total); |
533 | } |
534 | EXPORT_SYMBOL_GPL(blkcg_print_blkgs); |
535 | |
536 | /** |
537 | * __blkg_prfill_u64 - prfill helper for a single u64 value |
538 | * @sf: seq_file to print to |
539 | * @pd: policy private data of interest |
540 | * @v: value to print |
541 | * |
542 | * Print @v to @sf for the device assocaited with @pd. |
543 | */ |
544 | u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) |
545 | { |
546 | const char *dname = blkg_dev_name(pd->blkg); |
547 | |
548 | if (!dname) |
549 | return 0; |
550 | |
551 | seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); |
552 | return v; |
553 | } |
554 | EXPORT_SYMBOL_GPL(__blkg_prfill_u64); |
555 | |
556 | /** |
557 | * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat |
558 | * @sf: seq_file to print to |
559 | * @pd: policy private data of interest |
560 | * @rwstat: rwstat to print |
561 | * |
562 | * Print @rwstat to @sf for the device assocaited with @pd. |
563 | */ |
564 | u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, |
565 | const struct blkg_rwstat *rwstat) |
566 | { |
567 | static const char *rwstr[] = { |
568 | [BLKG_RWSTAT_READ] = "Read", |
569 | [BLKG_RWSTAT_WRITE] = "Write", |
570 | [BLKG_RWSTAT_SYNC] = "Sync", |
571 | [BLKG_RWSTAT_ASYNC] = "Async", |
572 | }; |
573 | const char *dname = blkg_dev_name(pd->blkg); |
574 | u64 v; |
575 | int i; |
576 | |
577 | if (!dname) |
578 | return 0; |
579 | |
580 | for (i = 0; i < BLKG_RWSTAT_NR; i++) |
581 | seq_printf(sf, "%s %s %llu\n", dname, rwstr[i], |
582 | (unsigned long long)rwstat->cnt[i]); |
583 | |
584 | v = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE]; |
585 | seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v); |
586 | return v; |
587 | } |
588 | EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat); |
589 | |
590 | /** |
591 | * blkg_prfill_stat - prfill callback for blkg_stat |
592 | * @sf: seq_file to print to |
593 | * @pd: policy private data of interest |
594 | * @off: offset to the blkg_stat in @pd |
595 | * |
596 | * prfill callback for printing a blkg_stat. |
597 | */ |
598 | u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off) |
599 | { |
600 | return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off)); |
601 | } |
602 | EXPORT_SYMBOL_GPL(blkg_prfill_stat); |
603 | |
604 | /** |
605 | * blkg_prfill_rwstat - prfill callback for blkg_rwstat |
606 | * @sf: seq_file to print to |
607 | * @pd: policy private data of interest |
608 | * @off: offset to the blkg_rwstat in @pd |
609 | * |
610 | * prfill callback for printing a blkg_rwstat. |
611 | */ |
612 | u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, |
613 | int off) |
614 | { |
615 | struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off); |
616 | |
617 | return __blkg_prfill_rwstat(sf, pd, &rwstat); |
618 | } |
619 | EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); |
620 | |
621 | /** |
622 | * blkg_stat_recursive_sum - collect hierarchical blkg_stat |
623 | * @pd: policy private data of interest |
624 | * @off: offset to the blkg_stat in @pd |
625 | * |
626 | * Collect the blkg_stat specified by @off from @pd and all its online |
627 | * descendants and return the sum. The caller must be holding the queue |
628 | * lock for online tests. |
629 | */ |
630 | u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off) |
631 | { |
632 | struct blkcg_policy *pol = blkcg_policy[pd->plid]; |
633 | struct blkcg_gq *pos_blkg; |
634 | struct cgroup *pos_cgrp; |
635 | u64 sum; |
636 | |
637 | lockdep_assert_held(pd->blkg->q->queue_lock); |
638 | |
639 | sum = blkg_stat_read((void *)pd + off); |
640 | |
641 | rcu_read_lock(); |
642 | blkg_for_each_descendant_pre(pos_blkg, pos_cgrp, pd_to_blkg(pd)) { |
643 | struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol); |
644 | struct blkg_stat *stat = (void *)pos_pd + off; |
645 | |
646 | if (pos_blkg->online) |
647 | sum += blkg_stat_read(stat); |
648 | } |
649 | rcu_read_unlock(); |
650 | |
651 | return sum; |
652 | } |
653 | EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum); |
654 | |
655 | /** |
656 | * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat |
657 | * @pd: policy private data of interest |
658 | * @off: offset to the blkg_stat in @pd |
659 | * |
660 | * Collect the blkg_rwstat specified by @off from @pd and all its online |
661 | * descendants and return the sum. The caller must be holding the queue |
662 | * lock for online tests. |
663 | */ |
664 | struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd, |
665 | int off) |
666 | { |
667 | struct blkcg_policy *pol = blkcg_policy[pd->plid]; |
668 | struct blkcg_gq *pos_blkg; |
669 | struct cgroup *pos_cgrp; |
670 | struct blkg_rwstat sum; |
671 | int i; |
672 | |
673 | lockdep_assert_held(pd->blkg->q->queue_lock); |
674 | |
675 | sum = blkg_rwstat_read((void *)pd + off); |
676 | |
677 | rcu_read_lock(); |
678 | blkg_for_each_descendant_pre(pos_blkg, pos_cgrp, pd_to_blkg(pd)) { |
679 | struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol); |
680 | struct blkg_rwstat *rwstat = (void *)pos_pd + off; |
681 | struct blkg_rwstat tmp; |
682 | |
683 | if (!pos_blkg->online) |
684 | continue; |
685 | |
686 | tmp = blkg_rwstat_read(rwstat); |
687 | |
688 | for (i = 0; i < BLKG_RWSTAT_NR; i++) |
689 | sum.cnt[i] += tmp.cnt[i]; |
690 | } |
691 | rcu_read_unlock(); |
692 | |
693 | return sum; |
694 | } |
695 | EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum); |
696 | |
697 | /** |
698 | * blkg_conf_prep - parse and prepare for per-blkg config update |
699 | * @blkcg: target block cgroup |
700 | * @pol: target policy |
701 | * @input: input string |
702 | * @ctx: blkg_conf_ctx to be filled |
703 | * |
704 | * Parse per-blkg config update from @input and initialize @ctx with the |
705 | * result. @ctx->blkg points to the blkg to be updated and @ctx->v the new |
706 | * value. This function returns with RCU read lock and queue lock held and |
707 | * must be paired with blkg_conf_finish(). |
708 | */ |
709 | int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, |
710 | const char *input, struct blkg_conf_ctx *ctx) |
711 | __acquires(rcu) __acquires(disk->queue->queue_lock) |
712 | { |
713 | struct gendisk *disk; |
714 | struct blkcg_gq *blkg; |
715 | unsigned int major, minor; |
716 | unsigned long long v; |
717 | int part, ret; |
718 | |
719 | if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3) |
720 | return -EINVAL; |
721 | |
722 | disk = get_gendisk(MKDEV(major, minor), &part); |
723 | if (!disk || part) |
724 | return -EINVAL; |
725 | |
726 | rcu_read_lock(); |
727 | spin_lock_irq(disk->queue->queue_lock); |
728 | |
729 | if (blkcg_policy_enabled(disk->queue, pol)) |
730 | blkg = blkg_lookup_create(blkcg, disk->queue); |
731 | else |
732 | blkg = ERR_PTR(-EINVAL); |
733 | |
734 | if (IS_ERR(blkg)) { |
735 | ret = PTR_ERR(blkg); |
736 | rcu_read_unlock(); |
737 | spin_unlock_irq(disk->queue->queue_lock); |
738 | put_disk(disk); |
739 | /* |
740 | * If queue was bypassing, we should retry. Do so after a |
741 | * short msleep(). It isn't strictly necessary but queue |
742 | * can be bypassing for some time and it's always nice to |
743 | * avoid busy looping. |
744 | */ |
745 | if (ret == -EBUSY) { |
746 | msleep(10); |
747 | ret = restart_syscall(); |
748 | } |
749 | return ret; |
750 | } |
751 | |
752 | ctx->disk = disk; |
753 | ctx->blkg = blkg; |
754 | ctx->v = v; |
755 | return 0; |
756 | } |
757 | EXPORT_SYMBOL_GPL(blkg_conf_prep); |
758 | |
759 | /** |
760 | * blkg_conf_finish - finish up per-blkg config update |
761 | * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() |
762 | * |
763 | * Finish up after per-blkg config update. This function must be paired |
764 | * with blkg_conf_prep(). |
765 | */ |
766 | void blkg_conf_finish(struct blkg_conf_ctx *ctx) |
767 | __releases(ctx->disk->queue->queue_lock) __releases(rcu) |
768 | { |
769 | spin_unlock_irq(ctx->disk->queue->queue_lock); |
770 | rcu_read_unlock(); |
771 | put_disk(ctx->disk); |
772 | } |
773 | EXPORT_SYMBOL_GPL(blkg_conf_finish); |
774 | |
775 | struct cftype blkcg_files[] = { |
776 | { |
777 | .name = "reset_stats", |
778 | .write_u64 = blkcg_reset_stats, |
779 | }, |
780 | { } /* terminate */ |
781 | }; |
782 | |
783 | /** |
784 | * blkcg_css_offline - cgroup css_offline callback |
785 | * @cgroup: cgroup of interest |
786 | * |
787 | * This function is called when @cgroup is about to go away and responsible |
788 | * for shooting down all blkgs associated with @cgroup. blkgs should be |
789 | * removed while holding both q and blkcg locks. As blkcg lock is nested |
790 | * inside q lock, this function performs reverse double lock dancing. |
791 | * |
792 | * This is the blkcg counterpart of ioc_release_fn(). |
793 | */ |
794 | static void blkcg_css_offline(struct cgroup *cgroup) |
795 | { |
796 | struct blkcg *blkcg = cgroup_to_blkcg(cgroup); |
797 | |
798 | spin_lock_irq(&blkcg->lock); |
799 | |
800 | while (!hlist_empty(&blkcg->blkg_list)) { |
801 | struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first, |
802 | struct blkcg_gq, blkcg_node); |
803 | struct request_queue *q = blkg->q; |
804 | |
805 | if (spin_trylock(q->queue_lock)) { |
806 | blkg_destroy(blkg); |
807 | spin_unlock(q->queue_lock); |
808 | } else { |
809 | spin_unlock_irq(&blkcg->lock); |
810 | cpu_relax(); |
811 | spin_lock_irq(&blkcg->lock); |
812 | } |
813 | } |
814 | |
815 | spin_unlock_irq(&blkcg->lock); |
816 | } |
817 | |
818 | static void blkcg_css_free(struct cgroup *cgroup) |
819 | { |
820 | struct blkcg *blkcg = cgroup_to_blkcg(cgroup); |
821 | |
822 | if (blkcg != &blkcg_root) |
823 | kfree(blkcg); |
824 | } |
825 | |
826 | static struct cgroup_subsys_state *blkcg_css_alloc(struct cgroup *cgroup) |
827 | { |
828 | static atomic64_t id_seq = ATOMIC64_INIT(0); |
829 | struct blkcg *blkcg; |
830 | struct cgroup *parent = cgroup->parent; |
831 | |
832 | if (!parent) { |
833 | blkcg = &blkcg_root; |
834 | goto done; |
835 | } |
836 | |
837 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); |
838 | if (!blkcg) |
839 | return ERR_PTR(-ENOMEM); |
840 | |
841 | blkcg->cfq_weight = CFQ_WEIGHT_DEFAULT; |
842 | blkcg->cfq_leaf_weight = CFQ_WEIGHT_DEFAULT; |
843 | blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */ |
844 | done: |
845 | spin_lock_init(&blkcg->lock); |
846 | INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC); |
847 | INIT_HLIST_HEAD(&blkcg->blkg_list); |
848 | |
849 | return &blkcg->css; |
850 | } |
851 | |
852 | /** |
853 | * blkcg_init_queue - initialize blkcg part of request queue |
854 | * @q: request_queue to initialize |
855 | * |
856 | * Called from blk_alloc_queue_node(). Responsible for initializing blkcg |
857 | * part of new request_queue @q. |
858 | * |
859 | * RETURNS: |
860 | * 0 on success, -errno on failure. |
861 | */ |
862 | int blkcg_init_queue(struct request_queue *q) |
863 | { |
864 | might_sleep(); |
865 | |
866 | return blk_throtl_init(q); |
867 | } |
868 | |
869 | /** |
870 | * blkcg_drain_queue - drain blkcg part of request_queue |
871 | * @q: request_queue to drain |
872 | * |
873 | * Called from blk_drain_queue(). Responsible for draining blkcg part. |
874 | */ |
875 | void blkcg_drain_queue(struct request_queue *q) |
876 | { |
877 | lockdep_assert_held(q->queue_lock); |
878 | |
879 | blk_throtl_drain(q); |
880 | } |
881 | |
882 | /** |
883 | * blkcg_exit_queue - exit and release blkcg part of request_queue |
884 | * @q: request_queue being released |
885 | * |
886 | * Called from blk_release_queue(). Responsible for exiting blkcg part. |
887 | */ |
888 | void blkcg_exit_queue(struct request_queue *q) |
889 | { |
890 | spin_lock_irq(q->queue_lock); |
891 | blkg_destroy_all(q); |
892 | spin_unlock_irq(q->queue_lock); |
893 | |
894 | blk_throtl_exit(q); |
895 | } |
896 | |
897 | /* |
898 | * We cannot support shared io contexts, as we have no mean to support |
899 | * two tasks with the same ioc in two different groups without major rework |
900 | * of the main cic data structures. For now we allow a task to change |
901 | * its cgroup only if it's the only owner of its ioc. |
902 | */ |
903 | static int blkcg_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset) |
904 | { |
905 | struct task_struct *task; |
906 | struct io_context *ioc; |
907 | int ret = 0; |
908 | |
909 | /* task_lock() is needed to avoid races with exit_io_context() */ |
910 | cgroup_taskset_for_each(task, cgrp, tset) { |
911 | task_lock(task); |
912 | ioc = task->io_context; |
913 | if (ioc && atomic_read(&ioc->nr_tasks) > 1) |
914 | ret = -EINVAL; |
915 | task_unlock(task); |
916 | if (ret) |
917 | break; |
918 | } |
919 | return ret; |
920 | } |
921 | |
922 | struct cgroup_subsys blkio_subsys = { |
923 | .name = "blkio", |
924 | .css_alloc = blkcg_css_alloc, |
925 | .css_offline = blkcg_css_offline, |
926 | .css_free = blkcg_css_free, |
927 | .can_attach = blkcg_can_attach, |
928 | .subsys_id = blkio_subsys_id, |
929 | .base_cftypes = blkcg_files, |
930 | .module = THIS_MODULE, |
931 | |
932 | /* |
933 | * blkio subsystem is utterly broken in terms of hierarchy support. |
934 | * It treats all cgroups equally regardless of where they're |
935 | * located in the hierarchy - all cgroups are treated as if they're |
936 | * right below the root. Fix it and remove the following. |
937 | */ |
938 | .broken_hierarchy = true, |
939 | }; |
940 | EXPORT_SYMBOL_GPL(blkio_subsys); |
941 | |
942 | /** |
943 | * blkcg_activate_policy - activate a blkcg policy on a request_queue |
944 | * @q: request_queue of interest |
945 | * @pol: blkcg policy to activate |
946 | * |
947 | * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through |
948 | * bypass mode to populate its blkgs with policy_data for @pol. |
949 | * |
950 | * Activation happens with @q bypassed, so nobody would be accessing blkgs |
951 | * from IO path. Update of each blkg is protected by both queue and blkcg |
952 | * locks so that holding either lock and testing blkcg_policy_enabled() is |
953 | * always enough for dereferencing policy data. |
954 | * |
955 | * The caller is responsible for synchronizing [de]activations and policy |
956 | * [un]registerations. Returns 0 on success, -errno on failure. |
957 | */ |
958 | int blkcg_activate_policy(struct request_queue *q, |
959 | const struct blkcg_policy *pol) |
960 | { |
961 | LIST_HEAD(pds); |
962 | struct blkcg_gq *blkg, *new_blkg; |
963 | struct blkg_policy_data *pd, *n; |
964 | int cnt = 0, ret; |
965 | bool preloaded; |
966 | |
967 | if (blkcg_policy_enabled(q, pol)) |
968 | return 0; |
969 | |
970 | /* preallocations for root blkg */ |
971 | new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); |
972 | if (!new_blkg) |
973 | return -ENOMEM; |
974 | |
975 | preloaded = !radix_tree_preload(GFP_KERNEL); |
976 | |
977 | blk_queue_bypass_start(q); |
978 | |
979 | /* |
980 | * Make sure the root blkg exists and count the existing blkgs. As |
981 | * @q is bypassing at this point, blkg_lookup_create() can't be |
982 | * used. Open code it. |
983 | */ |
984 | spin_lock_irq(q->queue_lock); |
985 | |
986 | rcu_read_lock(); |
987 | blkg = __blkg_lookup(&blkcg_root, q, false); |
988 | if (blkg) |
989 | blkg_free(new_blkg); |
990 | else |
991 | blkg = blkg_create(&blkcg_root, q, new_blkg); |
992 | rcu_read_unlock(); |
993 | |
994 | if (preloaded) |
995 | radix_tree_preload_end(); |
996 | |
997 | if (IS_ERR(blkg)) { |
998 | ret = PTR_ERR(blkg); |
999 | goto out_unlock; |
1000 | } |
1001 | q->root_blkg = blkg; |
1002 | q->root_rl.blkg = blkg; |
1003 | |
1004 | list_for_each_entry(blkg, &q->blkg_list, q_node) |
1005 | cnt++; |
1006 | |
1007 | spin_unlock_irq(q->queue_lock); |
1008 | |
1009 | /* allocate policy_data for all existing blkgs */ |
1010 | while (cnt--) { |
1011 | pd = kzalloc_node(pol->pd_size, GFP_KERNEL, q->node); |
1012 | if (!pd) { |
1013 | ret = -ENOMEM; |
1014 | goto out_free; |
1015 | } |
1016 | list_add_tail(&pd->alloc_node, &pds); |
1017 | } |
1018 | |
1019 | /* |
1020 | * Install the allocated pds. With @q bypassing, no new blkg |
1021 | * should have been created while the queue lock was dropped. |
1022 | */ |
1023 | spin_lock_irq(q->queue_lock); |
1024 | |
1025 | list_for_each_entry(blkg, &q->blkg_list, q_node) { |
1026 | if (WARN_ON(list_empty(&pds))) { |
1027 | /* umm... this shouldn't happen, just abort */ |
1028 | ret = -ENOMEM; |
1029 | goto out_unlock; |
1030 | } |
1031 | pd = list_first_entry(&pds, struct blkg_policy_data, alloc_node); |
1032 | list_del_init(&pd->alloc_node); |
1033 | |
1034 | /* grab blkcg lock too while installing @pd on @blkg */ |
1035 | spin_lock(&blkg->blkcg->lock); |
1036 | |
1037 | blkg->pd[pol->plid] = pd; |
1038 | pd->blkg = blkg; |
1039 | pd->plid = pol->plid; |
1040 | pol->pd_init_fn(blkg); |
1041 | |
1042 | spin_unlock(&blkg->blkcg->lock); |
1043 | } |
1044 | |
1045 | __set_bit(pol->plid, q->blkcg_pols); |
1046 | ret = 0; |
1047 | out_unlock: |
1048 | spin_unlock_irq(q->queue_lock); |
1049 | out_free: |
1050 | blk_queue_bypass_end(q); |
1051 | list_for_each_entry_safe(pd, n, &pds, alloc_node) |
1052 | kfree(pd); |
1053 | return ret; |
1054 | } |
1055 | EXPORT_SYMBOL_GPL(blkcg_activate_policy); |
1056 | |
1057 | /** |
1058 | * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue |
1059 | * @q: request_queue of interest |
1060 | * @pol: blkcg policy to deactivate |
1061 | * |
1062 | * Deactivate @pol on @q. Follows the same synchronization rules as |
1063 | * blkcg_activate_policy(). |
1064 | */ |
1065 | void blkcg_deactivate_policy(struct request_queue *q, |
1066 | const struct blkcg_policy *pol) |
1067 | { |
1068 | struct blkcg_gq *blkg; |
1069 | |
1070 | if (!blkcg_policy_enabled(q, pol)) |
1071 | return; |
1072 | |
1073 | blk_queue_bypass_start(q); |
1074 | spin_lock_irq(q->queue_lock); |
1075 | |
1076 | __clear_bit(pol->plid, q->blkcg_pols); |
1077 | |
1078 | /* if no policy is left, no need for blkgs - shoot them down */ |
1079 | if (bitmap_empty(q->blkcg_pols, BLKCG_MAX_POLS)) |
1080 | blkg_destroy_all(q); |
1081 | |
1082 | list_for_each_entry(blkg, &q->blkg_list, q_node) { |
1083 | /* grab blkcg lock too while removing @pd from @blkg */ |
1084 | spin_lock(&blkg->blkcg->lock); |
1085 | |
1086 | if (pol->pd_offline_fn) |
1087 | pol->pd_offline_fn(blkg); |
1088 | if (pol->pd_exit_fn) |
1089 | pol->pd_exit_fn(blkg); |
1090 | |
1091 | kfree(blkg->pd[pol->plid]); |
1092 | blkg->pd[pol->plid] = NULL; |
1093 | |
1094 | spin_unlock(&blkg->blkcg->lock); |
1095 | } |
1096 | |
1097 | spin_unlock_irq(q->queue_lock); |
1098 | blk_queue_bypass_end(q); |
1099 | } |
1100 | EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); |
1101 | |
1102 | /** |
1103 | * blkcg_policy_register - register a blkcg policy |
1104 | * @pol: blkcg policy to register |
1105 | * |
1106 | * Register @pol with blkcg core. Might sleep and @pol may be modified on |
1107 | * successful registration. Returns 0 on success and -errno on failure. |
1108 | */ |
1109 | int blkcg_policy_register(struct blkcg_policy *pol) |
1110 | { |
1111 | int i, ret; |
1112 | |
1113 | if (WARN_ON(pol->pd_size < sizeof(struct blkg_policy_data))) |
1114 | return -EINVAL; |
1115 | |
1116 | mutex_lock(&blkcg_pol_mutex); |
1117 | |
1118 | /* find an empty slot */ |
1119 | ret = -ENOSPC; |
1120 | for (i = 0; i < BLKCG_MAX_POLS; i++) |
1121 | if (!blkcg_policy[i]) |
1122 | break; |
1123 | if (i >= BLKCG_MAX_POLS) |
1124 | goto out_unlock; |
1125 | |
1126 | /* register and update blkgs */ |
1127 | pol->plid = i; |
1128 | blkcg_policy[i] = pol; |
1129 | |
1130 | /* everything is in place, add intf files for the new policy */ |
1131 | if (pol->cftypes) |
1132 | WARN_ON(cgroup_add_cftypes(&blkio_subsys, pol->cftypes)); |
1133 | ret = 0; |
1134 | out_unlock: |
1135 | mutex_unlock(&blkcg_pol_mutex); |
1136 | return ret; |
1137 | } |
1138 | EXPORT_SYMBOL_GPL(blkcg_policy_register); |
1139 | |
1140 | /** |
1141 | * blkcg_policy_unregister - unregister a blkcg policy |
1142 | * @pol: blkcg policy to unregister |
1143 | * |
1144 | * Undo blkcg_policy_register(@pol). Might sleep. |
1145 | */ |
1146 | void blkcg_policy_unregister(struct blkcg_policy *pol) |
1147 | { |
1148 | mutex_lock(&blkcg_pol_mutex); |
1149 | |
1150 | if (WARN_ON(blkcg_policy[pol->plid] != pol)) |
1151 | goto out_unlock; |
1152 | |
1153 | /* kill the intf files first */ |
1154 | if (pol->cftypes) |
1155 | cgroup_rm_cftypes(&blkio_subsys, pol->cftypes); |
1156 | |
1157 | /* unregister and update blkgs */ |
1158 | blkcg_policy[pol->plid] = NULL; |
1159 | out_unlock: |
1160 | mutex_unlock(&blkcg_pol_mutex); |
1161 | } |
1162 | EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |
1163 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
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jz-2.6.37
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jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9