Commit | Line | Data |
---|---|---|
23f78d4a IM |
1 | /* |
2 | * RT-Mutexes: simple blocking mutual exclusion locks with PI support | |
3 | * | |
4 | * started by Ingo Molnar and Thomas Gleixner. | |
5 | * | |
6 | * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
7 | * Copyright (C) 2005-2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com> | |
8 | * Copyright (C) 2005 Kihon Technologies Inc., Steven Rostedt | |
9 | * Copyright (C) 2006 Esben Nielsen | |
d07fe82c SR |
10 | * |
11 | * See Documentation/rt-mutex-design.txt for details. | |
23f78d4a IM |
12 | */ |
13 | #include <linux/spinlock.h> | |
9984de1a | 14 | #include <linux/export.h> |
23f78d4a | 15 | #include <linux/sched.h> |
8bd75c77 | 16 | #include <linux/sched/rt.h> |
fb00aca4 | 17 | #include <linux/sched/deadline.h> |
23f78d4a IM |
18 | #include <linux/timer.h> |
19 | ||
20 | #include "rtmutex_common.h" | |
21 | ||
23f78d4a IM |
22 | /* |
23 | * lock->owner state tracking: | |
24 | * | |
8161239a LJ |
25 | * lock->owner holds the task_struct pointer of the owner. Bit 0 |
26 | * is used to keep track of the "lock has waiters" state. | |
23f78d4a | 27 | * |
8161239a LJ |
28 | * owner bit0 |
29 | * NULL 0 lock is free (fast acquire possible) | |
30 | * NULL 1 lock is free and has waiters and the top waiter | |
31 | * is going to take the lock* | |
32 | * taskpointer 0 lock is held (fast release possible) | |
33 | * taskpointer 1 lock is held and has waiters** | |
23f78d4a IM |
34 | * |
35 | * The fast atomic compare exchange based acquire and release is only | |
8161239a LJ |
36 | * possible when bit 0 of lock->owner is 0. |
37 | * | |
38 | * (*) It also can be a transitional state when grabbing the lock | |
39 | * with ->wait_lock is held. To prevent any fast path cmpxchg to the lock, | |
40 | * we need to set the bit0 before looking at the lock, and the owner may be | |
41 | * NULL in this small time, hence this can be a transitional state. | |
23f78d4a | 42 | * |
8161239a LJ |
43 | * (**) There is a small time when bit 0 is set but there are no |
44 | * waiters. This can happen when grabbing the lock in the slow path. | |
45 | * To prevent a cmpxchg of the owner releasing the lock, we need to | |
46 | * set this bit before looking at the lock. | |
23f78d4a IM |
47 | */ |
48 | ||
bd197234 | 49 | static void |
8161239a | 50 | rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner) |
23f78d4a | 51 | { |
8161239a | 52 | unsigned long val = (unsigned long)owner; |
23f78d4a IM |
53 | |
54 | if (rt_mutex_has_waiters(lock)) | |
55 | val |= RT_MUTEX_HAS_WAITERS; | |
56 | ||
57 | lock->owner = (struct task_struct *)val; | |
58 | } | |
59 | ||
60 | static inline void clear_rt_mutex_waiters(struct rt_mutex *lock) | |
61 | { | |
62 | lock->owner = (struct task_struct *) | |
63 | ((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS); | |
64 | } | |
65 | ||
66 | static void fixup_rt_mutex_waiters(struct rt_mutex *lock) | |
67 | { | |
68 | if (!rt_mutex_has_waiters(lock)) | |
69 | clear_rt_mutex_waiters(lock); | |
70 | } | |
71 | ||
bd197234 TG |
72 | /* |
73 | * We can speed up the acquire/release, if the architecture | |
74 | * supports cmpxchg and if there's no debugging state to be set up | |
75 | */ | |
76 | #if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES) | |
77 | # define rt_mutex_cmpxchg(l,c,n) (cmpxchg(&l->owner, c, n) == c) | |
78 | static inline void mark_rt_mutex_waiters(struct rt_mutex *lock) | |
79 | { | |
80 | unsigned long owner, *p = (unsigned long *) &lock->owner; | |
81 | ||
82 | do { | |
83 | owner = *p; | |
84 | } while (cmpxchg(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner); | |
85 | } | |
86 | #else | |
87 | # define rt_mutex_cmpxchg(l,c,n) (0) | |
88 | static inline void mark_rt_mutex_waiters(struct rt_mutex *lock) | |
89 | { | |
90 | lock->owner = (struct task_struct *) | |
91 | ((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS); | |
92 | } | |
93 | #endif | |
94 | ||
fb00aca4 PZ |
95 | static inline int |
96 | rt_mutex_waiter_less(struct rt_mutex_waiter *left, | |
97 | struct rt_mutex_waiter *right) | |
98 | { | |
2d3d891d | 99 | if (left->prio < right->prio) |
fb00aca4 PZ |
100 | return 1; |
101 | ||
102 | /* | |
2d3d891d DF |
103 | * If both waiters have dl_prio(), we check the deadlines of the |
104 | * associated tasks. | |
105 | * If left waiter has a dl_prio(), and we didn't return 1 above, | |
106 | * then right waiter has a dl_prio() too. | |
fb00aca4 | 107 | */ |
2d3d891d | 108 | if (dl_prio(left->prio)) |
fb00aca4 PZ |
109 | return (left->task->dl.deadline < right->task->dl.deadline); |
110 | ||
111 | return 0; | |
112 | } | |
113 | ||
114 | static void | |
115 | rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) | |
116 | { | |
117 | struct rb_node **link = &lock->waiters.rb_node; | |
118 | struct rb_node *parent = NULL; | |
119 | struct rt_mutex_waiter *entry; | |
120 | int leftmost = 1; | |
121 | ||
122 | while (*link) { | |
123 | parent = *link; | |
124 | entry = rb_entry(parent, struct rt_mutex_waiter, tree_entry); | |
125 | if (rt_mutex_waiter_less(waiter, entry)) { | |
126 | link = &parent->rb_left; | |
127 | } else { | |
128 | link = &parent->rb_right; | |
129 | leftmost = 0; | |
130 | } | |
131 | } | |
132 | ||
133 | if (leftmost) | |
134 | lock->waiters_leftmost = &waiter->tree_entry; | |
135 | ||
136 | rb_link_node(&waiter->tree_entry, parent, link); | |
137 | rb_insert_color(&waiter->tree_entry, &lock->waiters); | |
138 | } | |
139 | ||
140 | static void | |
141 | rt_mutex_dequeue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) | |
142 | { | |
143 | if (RB_EMPTY_NODE(&waiter->tree_entry)) | |
144 | return; | |
145 | ||
146 | if (lock->waiters_leftmost == &waiter->tree_entry) | |
147 | lock->waiters_leftmost = rb_next(&waiter->tree_entry); | |
148 | ||
149 | rb_erase(&waiter->tree_entry, &lock->waiters); | |
150 | RB_CLEAR_NODE(&waiter->tree_entry); | |
151 | } | |
152 | ||
153 | static void | |
154 | rt_mutex_enqueue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter) | |
155 | { | |
156 | struct rb_node **link = &task->pi_waiters.rb_node; | |
157 | struct rb_node *parent = NULL; | |
158 | struct rt_mutex_waiter *entry; | |
159 | int leftmost = 1; | |
160 | ||
161 | while (*link) { | |
162 | parent = *link; | |
163 | entry = rb_entry(parent, struct rt_mutex_waiter, pi_tree_entry); | |
164 | if (rt_mutex_waiter_less(waiter, entry)) { | |
165 | link = &parent->rb_left; | |
166 | } else { | |
167 | link = &parent->rb_right; | |
168 | leftmost = 0; | |
169 | } | |
170 | } | |
171 | ||
172 | if (leftmost) | |
173 | task->pi_waiters_leftmost = &waiter->pi_tree_entry; | |
174 | ||
175 | rb_link_node(&waiter->pi_tree_entry, parent, link); | |
176 | rb_insert_color(&waiter->pi_tree_entry, &task->pi_waiters); | |
177 | } | |
178 | ||
179 | static void | |
180 | rt_mutex_dequeue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter) | |
181 | { | |
182 | if (RB_EMPTY_NODE(&waiter->pi_tree_entry)) | |
183 | return; | |
184 | ||
185 | if (task->pi_waiters_leftmost == &waiter->pi_tree_entry) | |
186 | task->pi_waiters_leftmost = rb_next(&waiter->pi_tree_entry); | |
187 | ||
188 | rb_erase(&waiter->pi_tree_entry, &task->pi_waiters); | |
189 | RB_CLEAR_NODE(&waiter->pi_tree_entry); | |
190 | } | |
191 | ||
23f78d4a | 192 | /* |
fb00aca4 | 193 | * Calculate task priority from the waiter tree priority |
23f78d4a | 194 | * |
fb00aca4 | 195 | * Return task->normal_prio when the waiter tree is empty or when |
23f78d4a IM |
196 | * the waiter is not allowed to do priority boosting |
197 | */ | |
198 | int rt_mutex_getprio(struct task_struct *task) | |
199 | { | |
200 | if (likely(!task_has_pi_waiters(task))) | |
201 | return task->normal_prio; | |
202 | ||
2d3d891d | 203 | return min(task_top_pi_waiter(task)->prio, |
23f78d4a IM |
204 | task->normal_prio); |
205 | } | |
206 | ||
2d3d891d DF |
207 | struct task_struct *rt_mutex_get_top_task(struct task_struct *task) |
208 | { | |
209 | if (likely(!task_has_pi_waiters(task))) | |
210 | return NULL; | |
211 | ||
212 | return task_top_pi_waiter(task)->task; | |
213 | } | |
214 | ||
23f78d4a IM |
215 | /* |
216 | * Adjust the priority of a task, after its pi_waiters got modified. | |
217 | * | |
218 | * This can be both boosting and unboosting. task->pi_lock must be held. | |
219 | */ | |
bd197234 | 220 | static void __rt_mutex_adjust_prio(struct task_struct *task) |
23f78d4a IM |
221 | { |
222 | int prio = rt_mutex_getprio(task); | |
223 | ||
2d3d891d | 224 | if (task->prio != prio || dl_prio(prio)) |
23f78d4a IM |
225 | rt_mutex_setprio(task, prio); |
226 | } | |
227 | ||
228 | /* | |
229 | * Adjust task priority (undo boosting). Called from the exit path of | |
230 | * rt_mutex_slowunlock() and rt_mutex_slowlock(). | |
231 | * | |
232 | * (Note: We do this outside of the protection of lock->wait_lock to | |
233 | * allow the lock to be taken while or before we readjust the priority | |
234 | * of task. We do not use the spin_xx_mutex() variants here as we are | |
235 | * outside of the debug path.) | |
236 | */ | |
237 | static void rt_mutex_adjust_prio(struct task_struct *task) | |
238 | { | |
239 | unsigned long flags; | |
240 | ||
1d615482 | 241 | raw_spin_lock_irqsave(&task->pi_lock, flags); |
23f78d4a | 242 | __rt_mutex_adjust_prio(task); |
1d615482 | 243 | raw_spin_unlock_irqrestore(&task->pi_lock, flags); |
23f78d4a IM |
244 | } |
245 | ||
246 | /* | |
247 | * Max number of times we'll walk the boosting chain: | |
248 | */ | |
249 | int max_lock_depth = 1024; | |
250 | ||
251 | /* | |
252 | * Adjust the priority chain. Also used for deadlock detection. | |
253 | * Decreases task's usage by one - may thus free the task. | |
0c106173 JL |
254 | * |
255 | * @task: the task owning the mutex (owner) for which a chain walk is probably | |
256 | * needed | |
257 | * @deadlock_detect: do we have to carry out deadlock detection? | |
258 | * @orig_lock: the mutex (can be NULL if we are walking the chain to recheck | |
259 | * things for a task that has just got its priority adjusted, and | |
260 | * is waiting on a mutex) | |
261 | * @orig_waiter: rt_mutex_waiter struct for the task that has just donated | |
262 | * its priority to the mutex owner (can be NULL in the case | |
263 | * depicted above or if the top waiter is gone away and we are | |
264 | * actually deboosting the owner) | |
265 | * @top_task: the current top waiter | |
266 | * | |
23f78d4a IM |
267 | * Returns 0 or -EDEADLK. |
268 | */ | |
bd197234 TG |
269 | static int rt_mutex_adjust_prio_chain(struct task_struct *task, |
270 | int deadlock_detect, | |
271 | struct rt_mutex *orig_lock, | |
272 | struct rt_mutex_waiter *orig_waiter, | |
273 | struct task_struct *top_task) | |
23f78d4a IM |
274 | { |
275 | struct rt_mutex *lock; | |
276 | struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter; | |
277 | int detect_deadlock, ret = 0, depth = 0; | |
278 | unsigned long flags; | |
279 | ||
280 | detect_deadlock = debug_rt_mutex_detect_deadlock(orig_waiter, | |
281 | deadlock_detect); | |
282 | ||
283 | /* | |
284 | * The (de)boosting is a step by step approach with a lot of | |
285 | * pitfalls. We want this to be preemptible and we want hold a | |
286 | * maximum of two locks per step. So we have to check | |
287 | * carefully whether things change under us. | |
288 | */ | |
289 | again: | |
290 | if (++depth > max_lock_depth) { | |
291 | static int prev_max; | |
292 | ||
293 | /* | |
294 | * Print this only once. If the admin changes the limit, | |
295 | * print a new message when reaching the limit again. | |
296 | */ | |
297 | if (prev_max != max_lock_depth) { | |
298 | prev_max = max_lock_depth; | |
299 | printk(KERN_WARNING "Maximum lock depth %d reached " | |
300 | "task: %s (%d)\n", max_lock_depth, | |
ba25f9dc | 301 | top_task->comm, task_pid_nr(top_task)); |
23f78d4a IM |
302 | } |
303 | put_task_struct(task); | |
304 | ||
305 | return deadlock_detect ? -EDEADLK : 0; | |
306 | } | |
307 | retry: | |
308 | /* | |
309 | * Task can not go away as we did a get_task() before ! | |
310 | */ | |
1d615482 | 311 | raw_spin_lock_irqsave(&task->pi_lock, flags); |
23f78d4a IM |
312 | |
313 | waiter = task->pi_blocked_on; | |
314 | /* | |
315 | * Check whether the end of the boosting chain has been | |
316 | * reached or the state of the chain has changed while we | |
317 | * dropped the locks. | |
318 | */ | |
8161239a | 319 | if (!waiter) |
23f78d4a IM |
320 | goto out_unlock_pi; |
321 | ||
1a539a87 TG |
322 | /* |
323 | * Check the orig_waiter state. After we dropped the locks, | |
8161239a | 324 | * the previous owner of the lock might have released the lock. |
1a539a87 | 325 | */ |
8161239a | 326 | if (orig_waiter && !rt_mutex_owner(orig_lock)) |
1a539a87 TG |
327 | goto out_unlock_pi; |
328 | ||
329 | /* | |
330 | * Drop out, when the task has no waiters. Note, | |
331 | * top_waiter can be NULL, when we are in the deboosting | |
332 | * mode! | |
333 | */ | |
23f78d4a IM |
334 | if (top_waiter && (!task_has_pi_waiters(task) || |
335 | top_waiter != task_top_pi_waiter(task))) | |
336 | goto out_unlock_pi; | |
337 | ||
338 | /* | |
339 | * When deadlock detection is off then we check, if further | |
340 | * priority adjustment is necessary. | |
341 | */ | |
2d3d891d | 342 | if (!detect_deadlock && waiter->prio == task->prio) |
23f78d4a IM |
343 | goto out_unlock_pi; |
344 | ||
345 | lock = waiter->lock; | |
d209d74d | 346 | if (!raw_spin_trylock(&lock->wait_lock)) { |
1d615482 | 347 | raw_spin_unlock_irqrestore(&task->pi_lock, flags); |
23f78d4a IM |
348 | cpu_relax(); |
349 | goto retry; | |
350 | } | |
351 | ||
352 | /* Deadlock detection */ | |
95e02ca9 | 353 | if (lock == orig_lock || rt_mutex_owner(lock) == top_task) { |
23f78d4a | 354 | debug_rt_mutex_deadlock(deadlock_detect, orig_waiter, lock); |
d209d74d | 355 | raw_spin_unlock(&lock->wait_lock); |
23f78d4a IM |
356 | ret = deadlock_detect ? -EDEADLK : 0; |
357 | goto out_unlock_pi; | |
358 | } | |
359 | ||
360 | top_waiter = rt_mutex_top_waiter(lock); | |
361 | ||
362 | /* Requeue the waiter */ | |
fb00aca4 | 363 | rt_mutex_dequeue(lock, waiter); |
2d3d891d | 364 | waiter->prio = task->prio; |
fb00aca4 | 365 | rt_mutex_enqueue(lock, waiter); |
23f78d4a IM |
366 | |
367 | /* Release the task */ | |
1d615482 | 368 | raw_spin_unlock_irqrestore(&task->pi_lock, flags); |
8161239a LJ |
369 | if (!rt_mutex_owner(lock)) { |
370 | /* | |
371 | * If the requeue above changed the top waiter, then we need | |
372 | * to wake the new top waiter up to try to get the lock. | |
373 | */ | |
374 | ||
375 | if (top_waiter != rt_mutex_top_waiter(lock)) | |
376 | wake_up_process(rt_mutex_top_waiter(lock)->task); | |
377 | raw_spin_unlock(&lock->wait_lock); | |
378 | goto out_put_task; | |
379 | } | |
23f78d4a IM |
380 | put_task_struct(task); |
381 | ||
382 | /* Grab the next task */ | |
383 | task = rt_mutex_owner(lock); | |
db630637 | 384 | get_task_struct(task); |
1d615482 | 385 | raw_spin_lock_irqsave(&task->pi_lock, flags); |
23f78d4a IM |
386 | |
387 | if (waiter == rt_mutex_top_waiter(lock)) { | |
388 | /* Boost the owner */ | |
fb00aca4 PZ |
389 | rt_mutex_dequeue_pi(task, top_waiter); |
390 | rt_mutex_enqueue_pi(task, waiter); | |
23f78d4a IM |
391 | __rt_mutex_adjust_prio(task); |
392 | ||
393 | } else if (top_waiter == waiter) { | |
394 | /* Deboost the owner */ | |
fb00aca4 | 395 | rt_mutex_dequeue_pi(task, waiter); |
23f78d4a | 396 | waiter = rt_mutex_top_waiter(lock); |
fb00aca4 | 397 | rt_mutex_enqueue_pi(task, waiter); |
23f78d4a IM |
398 | __rt_mutex_adjust_prio(task); |
399 | } | |
400 | ||
1d615482 | 401 | raw_spin_unlock_irqrestore(&task->pi_lock, flags); |
23f78d4a IM |
402 | |
403 | top_waiter = rt_mutex_top_waiter(lock); | |
d209d74d | 404 | raw_spin_unlock(&lock->wait_lock); |
23f78d4a IM |
405 | |
406 | if (!detect_deadlock && waiter != top_waiter) | |
407 | goto out_put_task; | |
408 | ||
409 | goto again; | |
410 | ||
411 | out_unlock_pi: | |
1d615482 | 412 | raw_spin_unlock_irqrestore(&task->pi_lock, flags); |
23f78d4a IM |
413 | out_put_task: |
414 | put_task_struct(task); | |
36c8b586 | 415 | |
23f78d4a IM |
416 | return ret; |
417 | } | |
418 | ||
23f78d4a IM |
419 | /* |
420 | * Try to take an rt-mutex | |
421 | * | |
23f78d4a | 422 | * Must be called with lock->wait_lock held. |
8161239a LJ |
423 | * |
424 | * @lock: the lock to be acquired. | |
425 | * @task: the task which wants to acquire the lock | |
426 | * @waiter: the waiter that is queued to the lock's wait list. (could be NULL) | |
23f78d4a | 427 | */ |
8161239a LJ |
428 | static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task, |
429 | struct rt_mutex_waiter *waiter) | |
23f78d4a IM |
430 | { |
431 | /* | |
432 | * We have to be careful here if the atomic speedups are | |
433 | * enabled, such that, when | |
434 | * - no other waiter is on the lock | |
435 | * - the lock has been released since we did the cmpxchg | |
436 | * the lock can be released or taken while we are doing the | |
437 | * checks and marking the lock with RT_MUTEX_HAS_WAITERS. | |
438 | * | |
439 | * The atomic acquire/release aware variant of | |
440 | * mark_rt_mutex_waiters uses a cmpxchg loop. After setting | |
441 | * the WAITERS bit, the atomic release / acquire can not | |
442 | * happen anymore and lock->wait_lock protects us from the | |
443 | * non-atomic case. | |
444 | * | |
445 | * Note, that this might set lock->owner = | |
446 | * RT_MUTEX_HAS_WAITERS in the case the lock is not contended | |
447 | * any more. This is fixed up when we take the ownership. | |
448 | * This is the transitional state explained at the top of this file. | |
449 | */ | |
450 | mark_rt_mutex_waiters(lock); | |
451 | ||
8161239a | 452 | if (rt_mutex_owner(lock)) |
23f78d4a IM |
453 | return 0; |
454 | ||
8161239a LJ |
455 | /* |
456 | * It will get the lock because of one of these conditions: | |
457 | * 1) there is no waiter | |
458 | * 2) higher priority than waiters | |
459 | * 3) it is top waiter | |
460 | */ | |
461 | if (rt_mutex_has_waiters(lock)) { | |
2d3d891d | 462 | if (task->prio >= rt_mutex_top_waiter(lock)->prio) { |
8161239a LJ |
463 | if (!waiter || waiter != rt_mutex_top_waiter(lock)) |
464 | return 0; | |
465 | } | |
466 | } | |
467 | ||
468 | if (waiter || rt_mutex_has_waiters(lock)) { | |
469 | unsigned long flags; | |
470 | struct rt_mutex_waiter *top; | |
471 | ||
472 | raw_spin_lock_irqsave(&task->pi_lock, flags); | |
473 | ||
474 | /* remove the queued waiter. */ | |
475 | if (waiter) { | |
fb00aca4 | 476 | rt_mutex_dequeue(lock, waiter); |
8161239a LJ |
477 | task->pi_blocked_on = NULL; |
478 | } | |
479 | ||
480 | /* | |
481 | * We have to enqueue the top waiter(if it exists) into | |
482 | * task->pi_waiters list. | |
483 | */ | |
484 | if (rt_mutex_has_waiters(lock)) { | |
485 | top = rt_mutex_top_waiter(lock); | |
fb00aca4 | 486 | rt_mutex_enqueue_pi(task, top); |
8161239a LJ |
487 | } |
488 | raw_spin_unlock_irqrestore(&task->pi_lock, flags); | |
489 | } | |
490 | ||
23f78d4a | 491 | /* We got the lock. */ |
9a11b49a | 492 | debug_rt_mutex_lock(lock); |
23f78d4a | 493 | |
8161239a | 494 | rt_mutex_set_owner(lock, task); |
23f78d4a | 495 | |
8161239a | 496 | rt_mutex_deadlock_account_lock(lock, task); |
23f78d4a IM |
497 | |
498 | return 1; | |
499 | } | |
500 | ||
501 | /* | |
502 | * Task blocks on lock. | |
503 | * | |
504 | * Prepare waiter and propagate pi chain | |
505 | * | |
506 | * This must be called with lock->wait_lock held. | |
507 | */ | |
508 | static int task_blocks_on_rt_mutex(struct rt_mutex *lock, | |
509 | struct rt_mutex_waiter *waiter, | |
8dac456a | 510 | struct task_struct *task, |
9a11b49a | 511 | int detect_deadlock) |
23f78d4a | 512 | { |
36c8b586 | 513 | struct task_struct *owner = rt_mutex_owner(lock); |
23f78d4a | 514 | struct rt_mutex_waiter *top_waiter = waiter; |
23f78d4a | 515 | unsigned long flags; |
db630637 | 516 | int chain_walk = 0, res; |
23f78d4a | 517 | |
1d615482 | 518 | raw_spin_lock_irqsave(&task->pi_lock, flags); |
8dac456a DH |
519 | __rt_mutex_adjust_prio(task); |
520 | waiter->task = task; | |
23f78d4a | 521 | waiter->lock = lock; |
2d3d891d | 522 | waiter->prio = task->prio; |
23f78d4a IM |
523 | |
524 | /* Get the top priority waiter on the lock */ | |
525 | if (rt_mutex_has_waiters(lock)) | |
526 | top_waiter = rt_mutex_top_waiter(lock); | |
fb00aca4 | 527 | rt_mutex_enqueue(lock, waiter); |
23f78d4a | 528 | |
8dac456a | 529 | task->pi_blocked_on = waiter; |
23f78d4a | 530 | |
1d615482 | 531 | raw_spin_unlock_irqrestore(&task->pi_lock, flags); |
23f78d4a | 532 | |
8161239a LJ |
533 | if (!owner) |
534 | return 0; | |
535 | ||
23f78d4a | 536 | if (waiter == rt_mutex_top_waiter(lock)) { |
1d615482 | 537 | raw_spin_lock_irqsave(&owner->pi_lock, flags); |
fb00aca4 PZ |
538 | rt_mutex_dequeue_pi(owner, top_waiter); |
539 | rt_mutex_enqueue_pi(owner, waiter); | |
23f78d4a IM |
540 | |
541 | __rt_mutex_adjust_prio(owner); | |
db630637 SR |
542 | if (owner->pi_blocked_on) |
543 | chain_walk = 1; | |
1d615482 | 544 | raw_spin_unlock_irqrestore(&owner->pi_lock, flags); |
23f78d4a | 545 | } |
db630637 SR |
546 | else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock)) |
547 | chain_walk = 1; | |
548 | ||
549 | if (!chain_walk) | |
23f78d4a IM |
550 | return 0; |
551 | ||
db630637 SR |
552 | /* |
553 | * The owner can't disappear while holding a lock, | |
554 | * so the owner struct is protected by wait_lock. | |
555 | * Gets dropped in rt_mutex_adjust_prio_chain()! | |
556 | */ | |
557 | get_task_struct(owner); | |
558 | ||
d209d74d | 559 | raw_spin_unlock(&lock->wait_lock); |
23f78d4a | 560 | |
95e02ca9 | 561 | res = rt_mutex_adjust_prio_chain(owner, detect_deadlock, lock, waiter, |
8dac456a | 562 | task); |
23f78d4a | 563 | |
d209d74d | 564 | raw_spin_lock(&lock->wait_lock); |
23f78d4a IM |
565 | |
566 | return res; | |
567 | } | |
568 | ||
569 | /* | |
570 | * Wake up the next waiter on the lock. | |
571 | * | |
8161239a | 572 | * Remove the top waiter from the current tasks waiter list and wake it up. |
23f78d4a IM |
573 | * |
574 | * Called with lock->wait_lock held. | |
575 | */ | |
576 | static void wakeup_next_waiter(struct rt_mutex *lock) | |
577 | { | |
578 | struct rt_mutex_waiter *waiter; | |
23f78d4a IM |
579 | unsigned long flags; |
580 | ||
1d615482 | 581 | raw_spin_lock_irqsave(¤t->pi_lock, flags); |
23f78d4a IM |
582 | |
583 | waiter = rt_mutex_top_waiter(lock); | |
23f78d4a IM |
584 | |
585 | /* | |
586 | * Remove it from current->pi_waiters. We do not adjust a | |
587 | * possible priority boost right now. We execute wakeup in the | |
588 | * boosted mode and go back to normal after releasing | |
589 | * lock->wait_lock. | |
590 | */ | |
fb00aca4 | 591 | rt_mutex_dequeue_pi(current, waiter); |
23f78d4a | 592 | |
8161239a | 593 | rt_mutex_set_owner(lock, NULL); |
23f78d4a | 594 | |
1d615482 | 595 | raw_spin_unlock_irqrestore(¤t->pi_lock, flags); |
23f78d4a | 596 | |
8161239a | 597 | wake_up_process(waiter->task); |
23f78d4a IM |
598 | } |
599 | ||
600 | /* | |
8161239a | 601 | * Remove a waiter from a lock and give up |
23f78d4a | 602 | * |
8161239a LJ |
603 | * Must be called with lock->wait_lock held and |
604 | * have just failed to try_to_take_rt_mutex(). | |
23f78d4a | 605 | */ |
bd197234 TG |
606 | static void remove_waiter(struct rt_mutex *lock, |
607 | struct rt_mutex_waiter *waiter) | |
23f78d4a IM |
608 | { |
609 | int first = (waiter == rt_mutex_top_waiter(lock)); | |
36c8b586 | 610 | struct task_struct *owner = rt_mutex_owner(lock); |
23f78d4a | 611 | unsigned long flags; |
db630637 | 612 | int chain_walk = 0; |
23f78d4a | 613 | |
1d615482 | 614 | raw_spin_lock_irqsave(¤t->pi_lock, flags); |
fb00aca4 | 615 | rt_mutex_dequeue(lock, waiter); |
23f78d4a | 616 | current->pi_blocked_on = NULL; |
1d615482 | 617 | raw_spin_unlock_irqrestore(¤t->pi_lock, flags); |
23f78d4a | 618 | |
8161239a LJ |
619 | if (!owner) |
620 | return; | |
621 | ||
622 | if (first) { | |
23f78d4a | 623 | |
1d615482 | 624 | raw_spin_lock_irqsave(&owner->pi_lock, flags); |
23f78d4a | 625 | |
fb00aca4 | 626 | rt_mutex_dequeue_pi(owner, waiter); |
23f78d4a IM |
627 | |
628 | if (rt_mutex_has_waiters(lock)) { | |
629 | struct rt_mutex_waiter *next; | |
630 | ||
631 | next = rt_mutex_top_waiter(lock); | |
fb00aca4 | 632 | rt_mutex_enqueue_pi(owner, next); |
23f78d4a IM |
633 | } |
634 | __rt_mutex_adjust_prio(owner); | |
635 | ||
db630637 SR |
636 | if (owner->pi_blocked_on) |
637 | chain_walk = 1; | |
638 | ||
1d615482 | 639 | raw_spin_unlock_irqrestore(&owner->pi_lock, flags); |
23f78d4a IM |
640 | } |
641 | ||
db630637 | 642 | if (!chain_walk) |
23f78d4a IM |
643 | return; |
644 | ||
db630637 SR |
645 | /* gets dropped in rt_mutex_adjust_prio_chain()! */ |
646 | get_task_struct(owner); | |
647 | ||
d209d74d | 648 | raw_spin_unlock(&lock->wait_lock); |
23f78d4a | 649 | |
9a11b49a | 650 | rt_mutex_adjust_prio_chain(owner, 0, lock, NULL, current); |
23f78d4a | 651 | |
d209d74d | 652 | raw_spin_lock(&lock->wait_lock); |
23f78d4a IM |
653 | } |
654 | ||
95e02ca9 TG |
655 | /* |
656 | * Recheck the pi chain, in case we got a priority setting | |
657 | * | |
658 | * Called from sched_setscheduler | |
659 | */ | |
660 | void rt_mutex_adjust_pi(struct task_struct *task) | |
661 | { | |
662 | struct rt_mutex_waiter *waiter; | |
663 | unsigned long flags; | |
664 | ||
1d615482 | 665 | raw_spin_lock_irqsave(&task->pi_lock, flags); |
95e02ca9 TG |
666 | |
667 | waiter = task->pi_blocked_on; | |
2d3d891d DF |
668 | if (!waiter || (waiter->prio == task->prio && |
669 | !dl_prio(task->prio))) { | |
1d615482 | 670 | raw_spin_unlock_irqrestore(&task->pi_lock, flags); |
95e02ca9 TG |
671 | return; |
672 | } | |
673 | ||
1d615482 | 674 | raw_spin_unlock_irqrestore(&task->pi_lock, flags); |
95e02ca9 | 675 | |
db630637 SR |
676 | /* gets dropped in rt_mutex_adjust_prio_chain()! */ |
677 | get_task_struct(task); | |
9a11b49a | 678 | rt_mutex_adjust_prio_chain(task, 0, NULL, NULL, task); |
95e02ca9 TG |
679 | } |
680 | ||
8dac456a DH |
681 | /** |
682 | * __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop | |
683 | * @lock: the rt_mutex to take | |
684 | * @state: the state the task should block in (TASK_INTERRUPTIBLE | |
685 | * or TASK_UNINTERRUPTIBLE) | |
686 | * @timeout: the pre-initialized and started timer, or NULL for none | |
687 | * @waiter: the pre-initialized rt_mutex_waiter | |
8dac456a DH |
688 | * |
689 | * lock->wait_lock must be held by the caller. | |
23f78d4a IM |
690 | */ |
691 | static int __sched | |
8dac456a DH |
692 | __rt_mutex_slowlock(struct rt_mutex *lock, int state, |
693 | struct hrtimer_sleeper *timeout, | |
8161239a | 694 | struct rt_mutex_waiter *waiter) |
23f78d4a | 695 | { |
23f78d4a IM |
696 | int ret = 0; |
697 | ||
23f78d4a IM |
698 | for (;;) { |
699 | /* Try to acquire the lock: */ | |
8161239a | 700 | if (try_to_take_rt_mutex(lock, current, waiter)) |
23f78d4a IM |
701 | break; |
702 | ||
703 | /* | |
704 | * TASK_INTERRUPTIBLE checks for signals and | |
705 | * timeout. Ignored otherwise. | |
706 | */ | |
707 | if (unlikely(state == TASK_INTERRUPTIBLE)) { | |
708 | /* Signal pending? */ | |
709 | if (signal_pending(current)) | |
710 | ret = -EINTR; | |
711 | if (timeout && !timeout->task) | |
712 | ret = -ETIMEDOUT; | |
713 | if (ret) | |
714 | break; | |
715 | } | |
716 | ||
d209d74d | 717 | raw_spin_unlock(&lock->wait_lock); |
23f78d4a | 718 | |
8dac456a | 719 | debug_rt_mutex_print_deadlock(waiter); |
23f78d4a | 720 | |
8161239a | 721 | schedule_rt_mutex(lock); |
23f78d4a | 722 | |
d209d74d | 723 | raw_spin_lock(&lock->wait_lock); |
23f78d4a IM |
724 | set_current_state(state); |
725 | } | |
726 | ||
8dac456a DH |
727 | return ret; |
728 | } | |
729 | ||
730 | /* | |
731 | * Slow path lock function: | |
732 | */ | |
733 | static int __sched | |
734 | rt_mutex_slowlock(struct rt_mutex *lock, int state, | |
735 | struct hrtimer_sleeper *timeout, | |
736 | int detect_deadlock) | |
737 | { | |
738 | struct rt_mutex_waiter waiter; | |
739 | int ret = 0; | |
740 | ||
741 | debug_rt_mutex_init_waiter(&waiter); | |
fb00aca4 PZ |
742 | RB_CLEAR_NODE(&waiter.pi_tree_entry); |
743 | RB_CLEAR_NODE(&waiter.tree_entry); | |
8dac456a | 744 | |
d209d74d | 745 | raw_spin_lock(&lock->wait_lock); |
8dac456a DH |
746 | |
747 | /* Try to acquire the lock again: */ | |
8161239a | 748 | if (try_to_take_rt_mutex(lock, current, NULL)) { |
d209d74d | 749 | raw_spin_unlock(&lock->wait_lock); |
8dac456a DH |
750 | return 0; |
751 | } | |
752 | ||
753 | set_current_state(state); | |
754 | ||
755 | /* Setup the timer, when timeout != NULL */ | |
756 | if (unlikely(timeout)) { | |
757 | hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS); | |
758 | if (!hrtimer_active(&timeout->timer)) | |
759 | timeout->task = NULL; | |
760 | } | |
761 | ||
8161239a LJ |
762 | ret = task_blocks_on_rt_mutex(lock, &waiter, current, detect_deadlock); |
763 | ||
764 | if (likely(!ret)) | |
765 | ret = __rt_mutex_slowlock(lock, state, timeout, &waiter); | |
8dac456a | 766 | |
23f78d4a IM |
767 | set_current_state(TASK_RUNNING); |
768 | ||
8161239a | 769 | if (unlikely(ret)) |
9a11b49a | 770 | remove_waiter(lock, &waiter); |
23f78d4a IM |
771 | |
772 | /* | |
773 | * try_to_take_rt_mutex() sets the waiter bit | |
774 | * unconditionally. We might have to fix that up. | |
775 | */ | |
776 | fixup_rt_mutex_waiters(lock); | |
777 | ||
d209d74d | 778 | raw_spin_unlock(&lock->wait_lock); |
23f78d4a IM |
779 | |
780 | /* Remove pending timer: */ | |
781 | if (unlikely(timeout)) | |
782 | hrtimer_cancel(&timeout->timer); | |
783 | ||
23f78d4a IM |
784 | debug_rt_mutex_free_waiter(&waiter); |
785 | ||
786 | return ret; | |
787 | } | |
788 | ||
789 | /* | |
790 | * Slow path try-lock function: | |
791 | */ | |
792 | static inline int | |
9a11b49a | 793 | rt_mutex_slowtrylock(struct rt_mutex *lock) |
23f78d4a IM |
794 | { |
795 | int ret = 0; | |
796 | ||
d209d74d | 797 | raw_spin_lock(&lock->wait_lock); |
23f78d4a IM |
798 | |
799 | if (likely(rt_mutex_owner(lock) != current)) { | |
800 | ||
8161239a | 801 | ret = try_to_take_rt_mutex(lock, current, NULL); |
23f78d4a IM |
802 | /* |
803 | * try_to_take_rt_mutex() sets the lock waiters | |
804 | * bit unconditionally. Clean this up. | |
805 | */ | |
806 | fixup_rt_mutex_waiters(lock); | |
807 | } | |
808 | ||
d209d74d | 809 | raw_spin_unlock(&lock->wait_lock); |
23f78d4a IM |
810 | |
811 | return ret; | |
812 | } | |
813 | ||
814 | /* | |
815 | * Slow path to release a rt-mutex: | |
816 | */ | |
817 | static void __sched | |
818 | rt_mutex_slowunlock(struct rt_mutex *lock) | |
819 | { | |
d209d74d | 820 | raw_spin_lock(&lock->wait_lock); |
23f78d4a IM |
821 | |
822 | debug_rt_mutex_unlock(lock); | |
823 | ||
824 | rt_mutex_deadlock_account_unlock(current); | |
825 | ||
826 | if (!rt_mutex_has_waiters(lock)) { | |
827 | lock->owner = NULL; | |
d209d74d | 828 | raw_spin_unlock(&lock->wait_lock); |
23f78d4a IM |
829 | return; |
830 | } | |
831 | ||
832 | wakeup_next_waiter(lock); | |
833 | ||
d209d74d | 834 | raw_spin_unlock(&lock->wait_lock); |
23f78d4a IM |
835 | |
836 | /* Undo pi boosting if necessary: */ | |
837 | rt_mutex_adjust_prio(current); | |
838 | } | |
839 | ||
840 | /* | |
841 | * debug aware fast / slowpath lock,trylock,unlock | |
842 | * | |
843 | * The atomic acquire/release ops are compiled away, when either the | |
844 | * architecture does not support cmpxchg or when debugging is enabled. | |
845 | */ | |
846 | static inline int | |
847 | rt_mutex_fastlock(struct rt_mutex *lock, int state, | |
848 | int detect_deadlock, | |
849 | int (*slowfn)(struct rt_mutex *lock, int state, | |
850 | struct hrtimer_sleeper *timeout, | |
9a11b49a | 851 | int detect_deadlock)) |
23f78d4a IM |
852 | { |
853 | if (!detect_deadlock && likely(rt_mutex_cmpxchg(lock, NULL, current))) { | |
854 | rt_mutex_deadlock_account_lock(lock, current); | |
855 | return 0; | |
856 | } else | |
9a11b49a | 857 | return slowfn(lock, state, NULL, detect_deadlock); |
23f78d4a IM |
858 | } |
859 | ||
860 | static inline int | |
861 | rt_mutex_timed_fastlock(struct rt_mutex *lock, int state, | |
862 | struct hrtimer_sleeper *timeout, int detect_deadlock, | |
863 | int (*slowfn)(struct rt_mutex *lock, int state, | |
864 | struct hrtimer_sleeper *timeout, | |
9a11b49a | 865 | int detect_deadlock)) |
23f78d4a IM |
866 | { |
867 | if (!detect_deadlock && likely(rt_mutex_cmpxchg(lock, NULL, current))) { | |
868 | rt_mutex_deadlock_account_lock(lock, current); | |
869 | return 0; | |
870 | } else | |
9a11b49a | 871 | return slowfn(lock, state, timeout, detect_deadlock); |
23f78d4a IM |
872 | } |
873 | ||
874 | static inline int | |
875 | rt_mutex_fasttrylock(struct rt_mutex *lock, | |
9a11b49a | 876 | int (*slowfn)(struct rt_mutex *lock)) |
23f78d4a IM |
877 | { |
878 | if (likely(rt_mutex_cmpxchg(lock, NULL, current))) { | |
879 | rt_mutex_deadlock_account_lock(lock, current); | |
880 | return 1; | |
881 | } | |
9a11b49a | 882 | return slowfn(lock); |
23f78d4a IM |
883 | } |
884 | ||
885 | static inline void | |
886 | rt_mutex_fastunlock(struct rt_mutex *lock, | |
887 | void (*slowfn)(struct rt_mutex *lock)) | |
888 | { | |
889 | if (likely(rt_mutex_cmpxchg(lock, current, NULL))) | |
890 | rt_mutex_deadlock_account_unlock(current); | |
891 | else | |
892 | slowfn(lock); | |
893 | } | |
894 | ||
895 | /** | |
896 | * rt_mutex_lock - lock a rt_mutex | |
897 | * | |
898 | * @lock: the rt_mutex to be locked | |
899 | */ | |
900 | void __sched rt_mutex_lock(struct rt_mutex *lock) | |
901 | { | |
902 | might_sleep(); | |
903 | ||
904 | rt_mutex_fastlock(lock, TASK_UNINTERRUPTIBLE, 0, rt_mutex_slowlock); | |
905 | } | |
906 | EXPORT_SYMBOL_GPL(rt_mutex_lock); | |
907 | ||
908 | /** | |
909 | * rt_mutex_lock_interruptible - lock a rt_mutex interruptible | |
910 | * | |
911 | * @lock: the rt_mutex to be locked | |
912 | * @detect_deadlock: deadlock detection on/off | |
913 | * | |
914 | * Returns: | |
915 | * 0 on success | |
916 | * -EINTR when interrupted by a signal | |
917 | * -EDEADLK when the lock would deadlock (when deadlock detection is on) | |
918 | */ | |
919 | int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock, | |
920 | int detect_deadlock) | |
921 | { | |
922 | might_sleep(); | |
923 | ||
924 | return rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE, | |
925 | detect_deadlock, rt_mutex_slowlock); | |
926 | } | |
927 | EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible); | |
928 | ||
929 | /** | |
23b94b96 LH |
930 | * rt_mutex_timed_lock - lock a rt_mutex interruptible |
931 | * the timeout structure is provided | |
932 | * by the caller | |
23f78d4a IM |
933 | * |
934 | * @lock: the rt_mutex to be locked | |
935 | * @timeout: timeout structure or NULL (no timeout) | |
936 | * @detect_deadlock: deadlock detection on/off | |
937 | * | |
938 | * Returns: | |
939 | * 0 on success | |
940 | * -EINTR when interrupted by a signal | |
3ac49a1c | 941 | * -ETIMEDOUT when the timeout expired |
23f78d4a IM |
942 | * -EDEADLK when the lock would deadlock (when deadlock detection is on) |
943 | */ | |
944 | int | |
945 | rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout, | |
946 | int detect_deadlock) | |
947 | { | |
948 | might_sleep(); | |
949 | ||
950 | return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout, | |
951 | detect_deadlock, rt_mutex_slowlock); | |
952 | } | |
953 | EXPORT_SYMBOL_GPL(rt_mutex_timed_lock); | |
954 | ||
955 | /** | |
956 | * rt_mutex_trylock - try to lock a rt_mutex | |
957 | * | |
958 | * @lock: the rt_mutex to be locked | |
959 | * | |
960 | * Returns 1 on success and 0 on contention | |
961 | */ | |
962 | int __sched rt_mutex_trylock(struct rt_mutex *lock) | |
963 | { | |
964 | return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock); | |
965 | } | |
966 | EXPORT_SYMBOL_GPL(rt_mutex_trylock); | |
967 | ||
968 | /** | |
969 | * rt_mutex_unlock - unlock a rt_mutex | |
970 | * | |
971 | * @lock: the rt_mutex to be unlocked | |
972 | */ | |
973 | void __sched rt_mutex_unlock(struct rt_mutex *lock) | |
974 | { | |
975 | rt_mutex_fastunlock(lock, rt_mutex_slowunlock); | |
976 | } | |
977 | EXPORT_SYMBOL_GPL(rt_mutex_unlock); | |
978 | ||
23b94b96 | 979 | /** |
23f78d4a IM |
980 | * rt_mutex_destroy - mark a mutex unusable |
981 | * @lock: the mutex to be destroyed | |
982 | * | |
983 | * This function marks the mutex uninitialized, and any subsequent | |
984 | * use of the mutex is forbidden. The mutex must not be locked when | |
985 | * this function is called. | |
986 | */ | |
987 | void rt_mutex_destroy(struct rt_mutex *lock) | |
988 | { | |
989 | WARN_ON(rt_mutex_is_locked(lock)); | |
990 | #ifdef CONFIG_DEBUG_RT_MUTEXES | |
991 | lock->magic = NULL; | |
992 | #endif | |
993 | } | |
994 | ||
995 | EXPORT_SYMBOL_GPL(rt_mutex_destroy); | |
996 | ||
997 | /** | |
998 | * __rt_mutex_init - initialize the rt lock | |
999 | * | |
1000 | * @lock: the rt lock to be initialized | |
1001 | * | |
1002 | * Initialize the rt lock to unlocked state. | |
1003 | * | |
1004 | * Initializing of a locked rt lock is not allowed | |
1005 | */ | |
1006 | void __rt_mutex_init(struct rt_mutex *lock, const char *name) | |
1007 | { | |
1008 | lock->owner = NULL; | |
d209d74d | 1009 | raw_spin_lock_init(&lock->wait_lock); |
fb00aca4 PZ |
1010 | lock->waiters = RB_ROOT; |
1011 | lock->waiters_leftmost = NULL; | |
23f78d4a IM |
1012 | |
1013 | debug_rt_mutex_init(lock, name); | |
1014 | } | |
1015 | EXPORT_SYMBOL_GPL(__rt_mutex_init); | |
0cdbee99 IM |
1016 | |
1017 | /** | |
1018 | * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a | |
1019 | * proxy owner | |
1020 | * | |
1021 | * @lock: the rt_mutex to be locked | |
1022 | * @proxy_owner:the task to set as owner | |
1023 | * | |
1024 | * No locking. Caller has to do serializing itself | |
1025 | * Special API call for PI-futex support | |
1026 | */ | |
1027 | void rt_mutex_init_proxy_locked(struct rt_mutex *lock, | |
1028 | struct task_struct *proxy_owner) | |
1029 | { | |
1030 | __rt_mutex_init(lock, NULL); | |
9a11b49a | 1031 | debug_rt_mutex_proxy_lock(lock, proxy_owner); |
8161239a | 1032 | rt_mutex_set_owner(lock, proxy_owner); |
0cdbee99 IM |
1033 | rt_mutex_deadlock_account_lock(lock, proxy_owner); |
1034 | } | |
1035 | ||
1036 | /** | |
1037 | * rt_mutex_proxy_unlock - release a lock on behalf of owner | |
1038 | * | |
1039 | * @lock: the rt_mutex to be locked | |
1040 | * | |
1041 | * No locking. Caller has to do serializing itself | |
1042 | * Special API call for PI-futex support | |
1043 | */ | |
1044 | void rt_mutex_proxy_unlock(struct rt_mutex *lock, | |
1045 | struct task_struct *proxy_owner) | |
1046 | { | |
1047 | debug_rt_mutex_proxy_unlock(lock); | |
8161239a | 1048 | rt_mutex_set_owner(lock, NULL); |
0cdbee99 IM |
1049 | rt_mutex_deadlock_account_unlock(proxy_owner); |
1050 | } | |
1051 | ||
8dac456a DH |
1052 | /** |
1053 | * rt_mutex_start_proxy_lock() - Start lock acquisition for another task | |
1054 | * @lock: the rt_mutex to take | |
1055 | * @waiter: the pre-initialized rt_mutex_waiter | |
1056 | * @task: the task to prepare | |
1057 | * @detect_deadlock: perform deadlock detection (1) or not (0) | |
1058 | * | |
1059 | * Returns: | |
1060 | * 0 - task blocked on lock | |
1061 | * 1 - acquired the lock for task, caller should wake it up | |
1062 | * <0 - error | |
1063 | * | |
1064 | * Special API call for FUTEX_REQUEUE_PI support. | |
1065 | */ | |
1066 | int rt_mutex_start_proxy_lock(struct rt_mutex *lock, | |
1067 | struct rt_mutex_waiter *waiter, | |
1068 | struct task_struct *task, int detect_deadlock) | |
1069 | { | |
1070 | int ret; | |
1071 | ||
d209d74d | 1072 | raw_spin_lock(&lock->wait_lock); |
8dac456a | 1073 | |
8161239a | 1074 | if (try_to_take_rt_mutex(lock, task, NULL)) { |
d209d74d | 1075 | raw_spin_unlock(&lock->wait_lock); |
8dac456a DH |
1076 | return 1; |
1077 | } | |
1078 | ||
1079 | ret = task_blocks_on_rt_mutex(lock, waiter, task, detect_deadlock); | |
1080 | ||
8161239a | 1081 | if (ret && !rt_mutex_owner(lock)) { |
8dac456a DH |
1082 | /* |
1083 | * Reset the return value. We might have | |
1084 | * returned with -EDEADLK and the owner | |
1085 | * released the lock while we were walking the | |
1086 | * pi chain. Let the waiter sort it out. | |
1087 | */ | |
1088 | ret = 0; | |
1089 | } | |
8161239a LJ |
1090 | |
1091 | if (unlikely(ret)) | |
1092 | remove_waiter(lock, waiter); | |
1093 | ||
d209d74d | 1094 | raw_spin_unlock(&lock->wait_lock); |
8dac456a DH |
1095 | |
1096 | debug_rt_mutex_print_deadlock(waiter); | |
1097 | ||
1098 | return ret; | |
1099 | } | |
1100 | ||
0cdbee99 IM |
1101 | /** |
1102 | * rt_mutex_next_owner - return the next owner of the lock | |
1103 | * | |
1104 | * @lock: the rt lock query | |
1105 | * | |
1106 | * Returns the next owner of the lock or NULL | |
1107 | * | |
1108 | * Caller has to serialize against other accessors to the lock | |
1109 | * itself. | |
1110 | * | |
1111 | * Special API call for PI-futex support | |
1112 | */ | |
1113 | struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock) | |
1114 | { | |
1115 | if (!rt_mutex_has_waiters(lock)) | |
1116 | return NULL; | |
1117 | ||
1118 | return rt_mutex_top_waiter(lock)->task; | |
1119 | } | |
8dac456a DH |
1120 | |
1121 | /** | |
1122 | * rt_mutex_finish_proxy_lock() - Complete lock acquisition | |
1123 | * @lock: the rt_mutex we were woken on | |
1124 | * @to: the timeout, null if none. hrtimer should already have | |
1125 | * been started. | |
1126 | * @waiter: the pre-initialized rt_mutex_waiter | |
1127 | * @detect_deadlock: perform deadlock detection (1) or not (0) | |
1128 | * | |
1129 | * Complete the lock acquisition started our behalf by another thread. | |
1130 | * | |
1131 | * Returns: | |
1132 | * 0 - success | |
1133 | * <0 - error, one of -EINTR, -ETIMEDOUT, or -EDEADLK | |
1134 | * | |
1135 | * Special API call for PI-futex requeue support | |
1136 | */ | |
1137 | int rt_mutex_finish_proxy_lock(struct rt_mutex *lock, | |
1138 | struct hrtimer_sleeper *to, | |
1139 | struct rt_mutex_waiter *waiter, | |
1140 | int detect_deadlock) | |
1141 | { | |
1142 | int ret; | |
1143 | ||
d209d74d | 1144 | raw_spin_lock(&lock->wait_lock); |
8dac456a DH |
1145 | |
1146 | set_current_state(TASK_INTERRUPTIBLE); | |
1147 | ||
8161239a | 1148 | ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter); |
8dac456a DH |
1149 | |
1150 | set_current_state(TASK_RUNNING); | |
1151 | ||
8161239a | 1152 | if (unlikely(ret)) |
8dac456a DH |
1153 | remove_waiter(lock, waiter); |
1154 | ||
1155 | /* | |
1156 | * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might | |
1157 | * have to fix that up. | |
1158 | */ | |
1159 | fixup_rt_mutex_waiters(lock); | |
1160 | ||
d209d74d | 1161 | raw_spin_unlock(&lock->wait_lock); |
8dac456a | 1162 | |
8dac456a DH |
1163 | return ret; |
1164 | } |