Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Fast Userspace Mutexes (which I call "Futexes!"). | |
3 | * (C) Rusty Russell, IBM 2002 | |
4 | * | |
5 | * Generalized futexes, futex requeueing, misc fixes by Ingo Molnar | |
6 | * (C) Copyright 2003 Red Hat Inc, All Rights Reserved | |
7 | * | |
8 | * Removed page pinning, fix privately mapped COW pages and other cleanups | |
9 | * (C) Copyright 2003, 2004 Jamie Lokier | |
10 | * | |
0771dfef IM |
11 | * Robust futex support started by Ingo Molnar |
12 | * (C) Copyright 2006 Red Hat Inc, All Rights Reserved | |
13 | * Thanks to Thomas Gleixner for suggestions, analysis and fixes. | |
14 | * | |
c87e2837 IM |
15 | * PI-futex support started by Ingo Molnar and Thomas Gleixner |
16 | * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
17 | * Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com> | |
18 | * | |
34f01cc1 ED |
19 | * PRIVATE futexes by Eric Dumazet |
20 | * Copyright (C) 2007 Eric Dumazet <dada1@cosmosbay.com> | |
21 | * | |
1da177e4 LT |
22 | * Thanks to Ben LaHaise for yelling "hashed waitqueues" loudly |
23 | * enough at me, Linus for the original (flawed) idea, Matthew | |
24 | * Kirkwood for proof-of-concept implementation. | |
25 | * | |
26 | * "The futexes are also cursed." | |
27 | * "But they come in a choice of three flavours!" | |
28 | * | |
29 | * This program is free software; you can redistribute it and/or modify | |
30 | * it under the terms of the GNU General Public License as published by | |
31 | * the Free Software Foundation; either version 2 of the License, or | |
32 | * (at your option) any later version. | |
33 | * | |
34 | * This program is distributed in the hope that it will be useful, | |
35 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
36 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
37 | * GNU General Public License for more details. | |
38 | * | |
39 | * You should have received a copy of the GNU General Public License | |
40 | * along with this program; if not, write to the Free Software | |
41 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
42 | */ | |
43 | #include <linux/slab.h> | |
44 | #include <linux/poll.h> | |
45 | #include <linux/fs.h> | |
46 | #include <linux/file.h> | |
47 | #include <linux/jhash.h> | |
48 | #include <linux/init.h> | |
49 | #include <linux/futex.h> | |
50 | #include <linux/mount.h> | |
51 | #include <linux/pagemap.h> | |
52 | #include <linux/syscalls.h> | |
7ed20e1a | 53 | #include <linux/signal.h> |
9adef58b | 54 | #include <linux/module.h> |
fd5eea42 | 55 | #include <linux/magic.h> |
b488893a PE |
56 | #include <linux/pid.h> |
57 | #include <linux/nsproxy.h> | |
58 | ||
4732efbe | 59 | #include <asm/futex.h> |
1da177e4 | 60 | |
c87e2837 IM |
61 | #include "rtmutex_common.h" |
62 | ||
a0c1e907 TG |
63 | int __read_mostly futex_cmpxchg_enabled; |
64 | ||
1da177e4 LT |
65 | #define FUTEX_HASHBITS (CONFIG_BASE_SMALL ? 4 : 8) |
66 | ||
c87e2837 IM |
67 | /* |
68 | * Priority Inheritance state: | |
69 | */ | |
70 | struct futex_pi_state { | |
71 | /* | |
72 | * list of 'owned' pi_state instances - these have to be | |
73 | * cleaned up in do_exit() if the task exits prematurely: | |
74 | */ | |
75 | struct list_head list; | |
76 | ||
77 | /* | |
78 | * The PI object: | |
79 | */ | |
80 | struct rt_mutex pi_mutex; | |
81 | ||
82 | struct task_struct *owner; | |
83 | atomic_t refcount; | |
84 | ||
85 | union futex_key key; | |
86 | }; | |
87 | ||
1da177e4 LT |
88 | /* |
89 | * We use this hashed waitqueue instead of a normal wait_queue_t, so | |
90 | * we can wake only the relevant ones (hashed queues may be shared). | |
91 | * | |
92 | * A futex_q has a woken state, just like tasks have TASK_RUNNING. | |
ec92d082 | 93 | * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0. |
1da177e4 LT |
94 | * The order of wakup is always to make the first condition true, then |
95 | * wake up q->waiters, then make the second condition true. | |
96 | */ | |
97 | struct futex_q { | |
ec92d082 | 98 | struct plist_node list; |
1da177e4 LT |
99 | wait_queue_head_t waiters; |
100 | ||
e2970f2f | 101 | /* Which hash list lock to use: */ |
1da177e4 LT |
102 | spinlock_t *lock_ptr; |
103 | ||
e2970f2f | 104 | /* Key which the futex is hashed on: */ |
1da177e4 LT |
105 | union futex_key key; |
106 | ||
c87e2837 IM |
107 | /* Optional priority inheritance state: */ |
108 | struct futex_pi_state *pi_state; | |
109 | struct task_struct *task; | |
cd689985 TG |
110 | |
111 | /* Bitset for the optional bitmasked wakeup */ | |
112 | u32 bitset; | |
1da177e4 LT |
113 | }; |
114 | ||
115 | /* | |
116 | * Split the global futex_lock into every hash list lock. | |
117 | */ | |
118 | struct futex_hash_bucket { | |
ec92d082 PP |
119 | spinlock_t lock; |
120 | struct plist_head chain; | |
1da177e4 LT |
121 | }; |
122 | ||
123 | static struct futex_hash_bucket futex_queues[1<<FUTEX_HASHBITS]; | |
124 | ||
36cf3b5c TG |
125 | /* |
126 | * Take mm->mmap_sem, when futex is shared | |
127 | */ | |
128 | static inline void futex_lock_mm(struct rw_semaphore *fshared) | |
129 | { | |
130 | if (fshared) | |
131 | down_read(fshared); | |
132 | } | |
133 | ||
134 | /* | |
135 | * Release mm->mmap_sem, when the futex is shared | |
136 | */ | |
137 | static inline void futex_unlock_mm(struct rw_semaphore *fshared) | |
138 | { | |
139 | if (fshared) | |
140 | up_read(fshared); | |
141 | } | |
142 | ||
1da177e4 LT |
143 | /* |
144 | * We hash on the keys returned from get_futex_key (see below). | |
145 | */ | |
146 | static struct futex_hash_bucket *hash_futex(union futex_key *key) | |
147 | { | |
148 | u32 hash = jhash2((u32*)&key->both.word, | |
149 | (sizeof(key->both.word)+sizeof(key->both.ptr))/4, | |
150 | key->both.offset); | |
151 | return &futex_queues[hash & ((1 << FUTEX_HASHBITS)-1)]; | |
152 | } | |
153 | ||
154 | /* | |
155 | * Return 1 if two futex_keys are equal, 0 otherwise. | |
156 | */ | |
157 | static inline int match_futex(union futex_key *key1, union futex_key *key2) | |
158 | { | |
159 | return (key1->both.word == key2->both.word | |
160 | && key1->both.ptr == key2->both.ptr | |
161 | && key1->both.offset == key2->both.offset); | |
162 | } | |
163 | ||
34f01cc1 ED |
164 | /** |
165 | * get_futex_key - Get parameters which are the keys for a futex. | |
166 | * @uaddr: virtual address of the futex | |
167 | * @shared: NULL for a PROCESS_PRIVATE futex, | |
168 | * ¤t->mm->mmap_sem for a PROCESS_SHARED futex | |
169 | * @key: address where result is stored. | |
170 | * | |
171 | * Returns a negative error code or 0 | |
172 | * The key words are stored in *key on success. | |
1da177e4 | 173 | * |
f3a43f3f | 174 | * For shared mappings, it's (page->index, vma->vm_file->f_path.dentry->d_inode, |
1da177e4 LT |
175 | * offset_within_page). For private mappings, it's (uaddr, current->mm). |
176 | * We can usually work out the index without swapping in the page. | |
177 | * | |
34f01cc1 ED |
178 | * fshared is NULL for PROCESS_PRIVATE futexes |
179 | * For other futexes, it points to ¤t->mm->mmap_sem and | |
180 | * caller must have taken the reader lock. but NOT any spinlocks. | |
1da177e4 | 181 | */ |
fad23fc7 AB |
182 | static int get_futex_key(u32 __user *uaddr, struct rw_semaphore *fshared, |
183 | union futex_key *key) | |
1da177e4 | 184 | { |
e2970f2f | 185 | unsigned long address = (unsigned long)uaddr; |
1da177e4 LT |
186 | struct mm_struct *mm = current->mm; |
187 | struct vm_area_struct *vma; | |
188 | struct page *page; | |
189 | int err; | |
190 | ||
191 | /* | |
192 | * The futex address must be "naturally" aligned. | |
193 | */ | |
e2970f2f | 194 | key->both.offset = address % PAGE_SIZE; |
34f01cc1 | 195 | if (unlikely((address % sizeof(u32)) != 0)) |
1da177e4 | 196 | return -EINVAL; |
e2970f2f | 197 | address -= key->both.offset; |
1da177e4 | 198 | |
34f01cc1 ED |
199 | /* |
200 | * PROCESS_PRIVATE futexes are fast. | |
201 | * As the mm cannot disappear under us and the 'key' only needs | |
202 | * virtual address, we dont even have to find the underlying vma. | |
203 | * Note : We do have to check 'uaddr' is a valid user address, | |
204 | * but access_ok() should be faster than find_vma() | |
205 | */ | |
206 | if (!fshared) { | |
207 | if (unlikely(!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))) | |
208 | return -EFAULT; | |
209 | key->private.mm = mm; | |
210 | key->private.address = address; | |
211 | return 0; | |
212 | } | |
1da177e4 LT |
213 | /* |
214 | * The futex is hashed differently depending on whether | |
215 | * it's in a shared or private mapping. So check vma first. | |
216 | */ | |
e2970f2f | 217 | vma = find_extend_vma(mm, address); |
1da177e4 LT |
218 | if (unlikely(!vma)) |
219 | return -EFAULT; | |
220 | ||
221 | /* | |
222 | * Permissions. | |
223 | */ | |
224 | if (unlikely((vma->vm_flags & (VM_IO|VM_READ)) != VM_READ)) | |
225 | return (vma->vm_flags & VM_IO) ? -EPERM : -EACCES; | |
226 | ||
227 | /* | |
228 | * Private mappings are handled in a simple way. | |
229 | * | |
230 | * NOTE: When userspace waits on a MAP_SHARED mapping, even if | |
231 | * it's a read-only handle, it's expected that futexes attach to | |
232 | * the object not the particular process. Therefore we use | |
233 | * VM_MAYSHARE here, not VM_SHARED which is restricted to shared | |
234 | * mappings of _writable_ handles. | |
235 | */ | |
236 | if (likely(!(vma->vm_flags & VM_MAYSHARE))) { | |
34f01cc1 | 237 | key->both.offset |= FUT_OFF_MMSHARED; /* reference taken on mm */ |
1da177e4 | 238 | key->private.mm = mm; |
e2970f2f | 239 | key->private.address = address; |
1da177e4 LT |
240 | return 0; |
241 | } | |
242 | ||
243 | /* | |
244 | * Linear file mappings are also simple. | |
245 | */ | |
f3a43f3f | 246 | key->shared.inode = vma->vm_file->f_path.dentry->d_inode; |
34f01cc1 | 247 | key->both.offset |= FUT_OFF_INODE; /* inode-based key. */ |
1da177e4 | 248 | if (likely(!(vma->vm_flags & VM_NONLINEAR))) { |
e2970f2f | 249 | key->shared.pgoff = (((address - vma->vm_start) >> PAGE_SHIFT) |
1da177e4 LT |
250 | + vma->vm_pgoff); |
251 | return 0; | |
252 | } | |
253 | ||
254 | /* | |
255 | * We could walk the page table to read the non-linear | |
256 | * pte, and get the page index without fetching the page | |
257 | * from swap. But that's a lot of code to duplicate here | |
258 | * for a rare case, so we simply fetch the page. | |
259 | */ | |
e2970f2f | 260 | err = get_user_pages(current, mm, address, 1, 0, 0, &page, NULL); |
1da177e4 LT |
261 | if (err >= 0) { |
262 | key->shared.pgoff = | |
263 | page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
264 | put_page(page); | |
265 | return 0; | |
266 | } | |
267 | return err; | |
268 | } | |
269 | ||
270 | /* | |
271 | * Take a reference to the resource addressed by a key. | |
272 | * Can be called while holding spinlocks. | |
273 | * | |
1da177e4 | 274 | */ |
fad23fc7 | 275 | static void get_futex_key_refs(union futex_key *key) |
1da177e4 | 276 | { |
9dce07f1 | 277 | if (key->both.ptr == NULL) |
34f01cc1 ED |
278 | return; |
279 | switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { | |
280 | case FUT_OFF_INODE: | |
1da177e4 | 281 | atomic_inc(&key->shared.inode->i_count); |
34f01cc1 ED |
282 | break; |
283 | case FUT_OFF_MMSHARED: | |
1da177e4 | 284 | atomic_inc(&key->private.mm->mm_count); |
34f01cc1 | 285 | break; |
1da177e4 LT |
286 | } |
287 | } | |
288 | ||
289 | /* | |
290 | * Drop a reference to the resource addressed by a key. | |
291 | * The hash bucket spinlock must not be held. | |
292 | */ | |
fad23fc7 | 293 | static void drop_futex_key_refs(union futex_key *key) |
1da177e4 | 294 | { |
c80544dc | 295 | if (!key->both.ptr) |
34f01cc1 ED |
296 | return; |
297 | switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { | |
298 | case FUT_OFF_INODE: | |
1da177e4 | 299 | iput(key->shared.inode); |
34f01cc1 ED |
300 | break; |
301 | case FUT_OFF_MMSHARED: | |
1da177e4 | 302 | mmdrop(key->private.mm); |
34f01cc1 | 303 | break; |
1da177e4 LT |
304 | } |
305 | } | |
306 | ||
36cf3b5c TG |
307 | static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval) |
308 | { | |
309 | u32 curval; | |
310 | ||
311 | pagefault_disable(); | |
312 | curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval); | |
313 | pagefault_enable(); | |
314 | ||
315 | return curval; | |
316 | } | |
317 | ||
318 | static int get_futex_value_locked(u32 *dest, u32 __user *from) | |
1da177e4 LT |
319 | { |
320 | int ret; | |
321 | ||
a866374a | 322 | pagefault_disable(); |
e2970f2f | 323 | ret = __copy_from_user_inatomic(dest, from, sizeof(u32)); |
a866374a | 324 | pagefault_enable(); |
1da177e4 LT |
325 | |
326 | return ret ? -EFAULT : 0; | |
327 | } | |
328 | ||
c87e2837 | 329 | /* |
34f01cc1 ED |
330 | * Fault handling. |
331 | * if fshared is non NULL, current->mm->mmap_sem is already held | |
c87e2837 | 332 | */ |
34f01cc1 ED |
333 | static int futex_handle_fault(unsigned long address, |
334 | struct rw_semaphore *fshared, int attempt) | |
c87e2837 IM |
335 | { |
336 | struct vm_area_struct * vma; | |
337 | struct mm_struct *mm = current->mm; | |
34f01cc1 | 338 | int ret = -EFAULT; |
c87e2837 | 339 | |
34f01cc1 ED |
340 | if (attempt > 2) |
341 | return ret; | |
c87e2837 | 342 | |
34f01cc1 ED |
343 | if (!fshared) |
344 | down_read(&mm->mmap_sem); | |
345 | vma = find_vma(mm, address); | |
346 | if (vma && address >= vma->vm_start && | |
347 | (vma->vm_flags & VM_WRITE)) { | |
83c54070 NP |
348 | int fault; |
349 | fault = handle_mm_fault(mm, vma, address, 1); | |
350 | if (unlikely((fault & VM_FAULT_ERROR))) { | |
351 | #if 0 | |
352 | /* XXX: let's do this when we verify it is OK */ | |
353 | if (ret & VM_FAULT_OOM) | |
354 | ret = -ENOMEM; | |
355 | #endif | |
356 | } else { | |
34f01cc1 | 357 | ret = 0; |
83c54070 NP |
358 | if (fault & VM_FAULT_MAJOR) |
359 | current->maj_flt++; | |
360 | else | |
361 | current->min_flt++; | |
34f01cc1 | 362 | } |
c87e2837 | 363 | } |
34f01cc1 ED |
364 | if (!fshared) |
365 | up_read(&mm->mmap_sem); | |
366 | return ret; | |
c87e2837 IM |
367 | } |
368 | ||
369 | /* | |
370 | * PI code: | |
371 | */ | |
372 | static int refill_pi_state_cache(void) | |
373 | { | |
374 | struct futex_pi_state *pi_state; | |
375 | ||
376 | if (likely(current->pi_state_cache)) | |
377 | return 0; | |
378 | ||
4668edc3 | 379 | pi_state = kzalloc(sizeof(*pi_state), GFP_KERNEL); |
c87e2837 IM |
380 | |
381 | if (!pi_state) | |
382 | return -ENOMEM; | |
383 | ||
c87e2837 IM |
384 | INIT_LIST_HEAD(&pi_state->list); |
385 | /* pi_mutex gets initialized later */ | |
386 | pi_state->owner = NULL; | |
387 | atomic_set(&pi_state->refcount, 1); | |
388 | ||
389 | current->pi_state_cache = pi_state; | |
390 | ||
391 | return 0; | |
392 | } | |
393 | ||
394 | static struct futex_pi_state * alloc_pi_state(void) | |
395 | { | |
396 | struct futex_pi_state *pi_state = current->pi_state_cache; | |
397 | ||
398 | WARN_ON(!pi_state); | |
399 | current->pi_state_cache = NULL; | |
400 | ||
401 | return pi_state; | |
402 | } | |
403 | ||
404 | static void free_pi_state(struct futex_pi_state *pi_state) | |
405 | { | |
406 | if (!atomic_dec_and_test(&pi_state->refcount)) | |
407 | return; | |
408 | ||
409 | /* | |
410 | * If pi_state->owner is NULL, the owner is most probably dying | |
411 | * and has cleaned up the pi_state already | |
412 | */ | |
413 | if (pi_state->owner) { | |
414 | spin_lock_irq(&pi_state->owner->pi_lock); | |
415 | list_del_init(&pi_state->list); | |
416 | spin_unlock_irq(&pi_state->owner->pi_lock); | |
417 | ||
418 | rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner); | |
419 | } | |
420 | ||
421 | if (current->pi_state_cache) | |
422 | kfree(pi_state); | |
423 | else { | |
424 | /* | |
425 | * pi_state->list is already empty. | |
426 | * clear pi_state->owner. | |
427 | * refcount is at 0 - put it back to 1. | |
428 | */ | |
429 | pi_state->owner = NULL; | |
430 | atomic_set(&pi_state->refcount, 1); | |
431 | current->pi_state_cache = pi_state; | |
432 | } | |
433 | } | |
434 | ||
435 | /* | |
436 | * Look up the task based on what TID userspace gave us. | |
437 | * We dont trust it. | |
438 | */ | |
439 | static struct task_struct * futex_find_get_task(pid_t pid) | |
440 | { | |
441 | struct task_struct *p; | |
c69e8d9c | 442 | const struct cred *cred = current_cred(), *pcred; |
c87e2837 | 443 | |
d359b549 | 444 | rcu_read_lock(); |
228ebcbe | 445 | p = find_task_by_vpid(pid); |
c69e8d9c | 446 | if (!p) { |
a06381fe | 447 | p = ERR_PTR(-ESRCH); |
c69e8d9c DH |
448 | } else { |
449 | pcred = __task_cred(p); | |
450 | if (cred->euid != pcred->euid && | |
451 | cred->euid != pcred->uid) | |
452 | p = ERR_PTR(-ESRCH); | |
453 | else | |
454 | get_task_struct(p); | |
455 | } | |
a06381fe | 456 | |
d359b549 | 457 | rcu_read_unlock(); |
c87e2837 IM |
458 | |
459 | return p; | |
460 | } | |
461 | ||
462 | /* | |
463 | * This task is holding PI mutexes at exit time => bad. | |
464 | * Kernel cleans up PI-state, but userspace is likely hosed. | |
465 | * (Robust-futex cleanup is separate and might save the day for userspace.) | |
466 | */ | |
467 | void exit_pi_state_list(struct task_struct *curr) | |
468 | { | |
c87e2837 IM |
469 | struct list_head *next, *head = &curr->pi_state_list; |
470 | struct futex_pi_state *pi_state; | |
627371d7 | 471 | struct futex_hash_bucket *hb; |
c87e2837 IM |
472 | union futex_key key; |
473 | ||
a0c1e907 TG |
474 | if (!futex_cmpxchg_enabled) |
475 | return; | |
c87e2837 IM |
476 | /* |
477 | * We are a ZOMBIE and nobody can enqueue itself on | |
478 | * pi_state_list anymore, but we have to be careful | |
627371d7 | 479 | * versus waiters unqueueing themselves: |
c87e2837 IM |
480 | */ |
481 | spin_lock_irq(&curr->pi_lock); | |
482 | while (!list_empty(head)) { | |
483 | ||
484 | next = head->next; | |
485 | pi_state = list_entry(next, struct futex_pi_state, list); | |
486 | key = pi_state->key; | |
627371d7 | 487 | hb = hash_futex(&key); |
c87e2837 IM |
488 | spin_unlock_irq(&curr->pi_lock); |
489 | ||
c87e2837 IM |
490 | spin_lock(&hb->lock); |
491 | ||
492 | spin_lock_irq(&curr->pi_lock); | |
627371d7 IM |
493 | /* |
494 | * We dropped the pi-lock, so re-check whether this | |
495 | * task still owns the PI-state: | |
496 | */ | |
c87e2837 IM |
497 | if (head->next != next) { |
498 | spin_unlock(&hb->lock); | |
499 | continue; | |
500 | } | |
501 | ||
c87e2837 | 502 | WARN_ON(pi_state->owner != curr); |
627371d7 IM |
503 | WARN_ON(list_empty(&pi_state->list)); |
504 | list_del_init(&pi_state->list); | |
c87e2837 IM |
505 | pi_state->owner = NULL; |
506 | spin_unlock_irq(&curr->pi_lock); | |
507 | ||
508 | rt_mutex_unlock(&pi_state->pi_mutex); | |
509 | ||
510 | spin_unlock(&hb->lock); | |
511 | ||
512 | spin_lock_irq(&curr->pi_lock); | |
513 | } | |
514 | spin_unlock_irq(&curr->pi_lock); | |
515 | } | |
516 | ||
517 | static int | |
d0aa7a70 PP |
518 | lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, |
519 | union futex_key *key, struct futex_pi_state **ps) | |
c87e2837 IM |
520 | { |
521 | struct futex_pi_state *pi_state = NULL; | |
522 | struct futex_q *this, *next; | |
ec92d082 | 523 | struct plist_head *head; |
c87e2837 | 524 | struct task_struct *p; |
778e9a9c | 525 | pid_t pid = uval & FUTEX_TID_MASK; |
c87e2837 IM |
526 | |
527 | head = &hb->chain; | |
528 | ||
ec92d082 | 529 | plist_for_each_entry_safe(this, next, head, list) { |
d0aa7a70 | 530 | if (match_futex(&this->key, key)) { |
c87e2837 IM |
531 | /* |
532 | * Another waiter already exists - bump up | |
533 | * the refcount and return its pi_state: | |
534 | */ | |
535 | pi_state = this->pi_state; | |
06a9ec29 TG |
536 | /* |
537 | * Userspace might have messed up non PI and PI futexes | |
538 | */ | |
539 | if (unlikely(!pi_state)) | |
540 | return -EINVAL; | |
541 | ||
627371d7 | 542 | WARN_ON(!atomic_read(&pi_state->refcount)); |
778e9a9c AK |
543 | WARN_ON(pid && pi_state->owner && |
544 | pi_state->owner->pid != pid); | |
627371d7 | 545 | |
c87e2837 | 546 | atomic_inc(&pi_state->refcount); |
d0aa7a70 | 547 | *ps = pi_state; |
c87e2837 IM |
548 | |
549 | return 0; | |
550 | } | |
551 | } | |
552 | ||
553 | /* | |
e3f2ddea | 554 | * We are the first waiter - try to look up the real owner and attach |
778e9a9c | 555 | * the new pi_state to it, but bail out when TID = 0 |
c87e2837 | 556 | */ |
778e9a9c | 557 | if (!pid) |
e3f2ddea | 558 | return -ESRCH; |
c87e2837 | 559 | p = futex_find_get_task(pid); |
778e9a9c AK |
560 | if (IS_ERR(p)) |
561 | return PTR_ERR(p); | |
562 | ||
563 | /* | |
564 | * We need to look at the task state flags to figure out, | |
565 | * whether the task is exiting. To protect against the do_exit | |
566 | * change of the task flags, we do this protected by | |
567 | * p->pi_lock: | |
568 | */ | |
569 | spin_lock_irq(&p->pi_lock); | |
570 | if (unlikely(p->flags & PF_EXITING)) { | |
571 | /* | |
572 | * The task is on the way out. When PF_EXITPIDONE is | |
573 | * set, we know that the task has finished the | |
574 | * cleanup: | |
575 | */ | |
576 | int ret = (p->flags & PF_EXITPIDONE) ? -ESRCH : -EAGAIN; | |
577 | ||
578 | spin_unlock_irq(&p->pi_lock); | |
579 | put_task_struct(p); | |
580 | return ret; | |
581 | } | |
c87e2837 IM |
582 | |
583 | pi_state = alloc_pi_state(); | |
584 | ||
585 | /* | |
586 | * Initialize the pi_mutex in locked state and make 'p' | |
587 | * the owner of it: | |
588 | */ | |
589 | rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p); | |
590 | ||
591 | /* Store the key for possible exit cleanups: */ | |
d0aa7a70 | 592 | pi_state->key = *key; |
c87e2837 | 593 | |
627371d7 | 594 | WARN_ON(!list_empty(&pi_state->list)); |
c87e2837 IM |
595 | list_add(&pi_state->list, &p->pi_state_list); |
596 | pi_state->owner = p; | |
597 | spin_unlock_irq(&p->pi_lock); | |
598 | ||
599 | put_task_struct(p); | |
600 | ||
d0aa7a70 | 601 | *ps = pi_state; |
c87e2837 IM |
602 | |
603 | return 0; | |
604 | } | |
605 | ||
1da177e4 LT |
606 | /* |
607 | * The hash bucket lock must be held when this is called. | |
608 | * Afterwards, the futex_q must not be accessed. | |
609 | */ | |
610 | static void wake_futex(struct futex_q *q) | |
611 | { | |
ec92d082 | 612 | plist_del(&q->list, &q->list.plist); |
1da177e4 LT |
613 | /* |
614 | * The lock in wake_up_all() is a crucial memory barrier after the | |
ec92d082 | 615 | * plist_del() and also before assigning to q->lock_ptr. |
1da177e4 LT |
616 | */ |
617 | wake_up_all(&q->waiters); | |
618 | /* | |
619 | * The waiting task can free the futex_q as soon as this is written, | |
620 | * without taking any locks. This must come last. | |
8e31108b AM |
621 | * |
622 | * A memory barrier is required here to prevent the following store | |
623 | * to lock_ptr from getting ahead of the wakeup. Clearing the lock | |
624 | * at the end of wake_up_all() does not prevent this store from | |
625 | * moving. | |
1da177e4 | 626 | */ |
ccdea2f8 | 627 | smp_wmb(); |
1da177e4 LT |
628 | q->lock_ptr = NULL; |
629 | } | |
630 | ||
c87e2837 IM |
631 | static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this) |
632 | { | |
633 | struct task_struct *new_owner; | |
634 | struct futex_pi_state *pi_state = this->pi_state; | |
635 | u32 curval, newval; | |
636 | ||
637 | if (!pi_state) | |
638 | return -EINVAL; | |
639 | ||
21778867 | 640 | spin_lock(&pi_state->pi_mutex.wait_lock); |
c87e2837 IM |
641 | new_owner = rt_mutex_next_owner(&pi_state->pi_mutex); |
642 | ||
643 | /* | |
644 | * This happens when we have stolen the lock and the original | |
645 | * pending owner did not enqueue itself back on the rt_mutex. | |
646 | * Thats not a tragedy. We know that way, that a lock waiter | |
647 | * is on the fly. We make the futex_q waiter the pending owner. | |
648 | */ | |
649 | if (!new_owner) | |
650 | new_owner = this->task; | |
651 | ||
652 | /* | |
653 | * We pass it to the next owner. (The WAITERS bit is always | |
654 | * kept enabled while there is PI state around. We must also | |
655 | * preserve the owner died bit.) | |
656 | */ | |
e3f2ddea | 657 | if (!(uval & FUTEX_OWNER_DIED)) { |
778e9a9c AK |
658 | int ret = 0; |
659 | ||
b488893a | 660 | newval = FUTEX_WAITERS | task_pid_vnr(new_owner); |
e3f2ddea | 661 | |
36cf3b5c | 662 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
778e9a9c | 663 | |
e3f2ddea | 664 | if (curval == -EFAULT) |
778e9a9c | 665 | ret = -EFAULT; |
cde898fa | 666 | else if (curval != uval) |
778e9a9c AK |
667 | ret = -EINVAL; |
668 | if (ret) { | |
669 | spin_unlock(&pi_state->pi_mutex.wait_lock); | |
670 | return ret; | |
671 | } | |
e3f2ddea | 672 | } |
c87e2837 | 673 | |
627371d7 IM |
674 | spin_lock_irq(&pi_state->owner->pi_lock); |
675 | WARN_ON(list_empty(&pi_state->list)); | |
676 | list_del_init(&pi_state->list); | |
677 | spin_unlock_irq(&pi_state->owner->pi_lock); | |
678 | ||
679 | spin_lock_irq(&new_owner->pi_lock); | |
680 | WARN_ON(!list_empty(&pi_state->list)); | |
c87e2837 IM |
681 | list_add(&pi_state->list, &new_owner->pi_state_list); |
682 | pi_state->owner = new_owner; | |
627371d7 IM |
683 | spin_unlock_irq(&new_owner->pi_lock); |
684 | ||
21778867 | 685 | spin_unlock(&pi_state->pi_mutex.wait_lock); |
c87e2837 IM |
686 | rt_mutex_unlock(&pi_state->pi_mutex); |
687 | ||
688 | return 0; | |
689 | } | |
690 | ||
691 | static int unlock_futex_pi(u32 __user *uaddr, u32 uval) | |
692 | { | |
693 | u32 oldval; | |
694 | ||
695 | /* | |
696 | * There is no waiter, so we unlock the futex. The owner died | |
697 | * bit has not to be preserved here. We are the owner: | |
698 | */ | |
36cf3b5c | 699 | oldval = cmpxchg_futex_value_locked(uaddr, uval, 0); |
c87e2837 IM |
700 | |
701 | if (oldval == -EFAULT) | |
702 | return oldval; | |
703 | if (oldval != uval) | |
704 | return -EAGAIN; | |
705 | ||
706 | return 0; | |
707 | } | |
708 | ||
8b8f319f IM |
709 | /* |
710 | * Express the locking dependencies for lockdep: | |
711 | */ | |
712 | static inline void | |
713 | double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) | |
714 | { | |
715 | if (hb1 <= hb2) { | |
716 | spin_lock(&hb1->lock); | |
717 | if (hb1 < hb2) | |
718 | spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); | |
719 | } else { /* hb1 > hb2 */ | |
720 | spin_lock(&hb2->lock); | |
721 | spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); | |
722 | } | |
723 | } | |
724 | ||
1da177e4 LT |
725 | /* |
726 | * Wake up all waiters hashed on the physical page that is mapped | |
727 | * to this virtual address: | |
728 | */ | |
34f01cc1 | 729 | static int futex_wake(u32 __user *uaddr, struct rw_semaphore *fshared, |
cd689985 | 730 | int nr_wake, u32 bitset) |
1da177e4 | 731 | { |
e2970f2f | 732 | struct futex_hash_bucket *hb; |
1da177e4 | 733 | struct futex_q *this, *next; |
ec92d082 | 734 | struct plist_head *head; |
e2970f2f | 735 | union futex_key key; |
1da177e4 LT |
736 | int ret; |
737 | ||
cd689985 TG |
738 | if (!bitset) |
739 | return -EINVAL; | |
740 | ||
36cf3b5c | 741 | futex_lock_mm(fshared); |
1da177e4 | 742 | |
34f01cc1 | 743 | ret = get_futex_key(uaddr, fshared, &key); |
1da177e4 LT |
744 | if (unlikely(ret != 0)) |
745 | goto out; | |
746 | ||
e2970f2f IM |
747 | hb = hash_futex(&key); |
748 | spin_lock(&hb->lock); | |
749 | head = &hb->chain; | |
1da177e4 | 750 | |
ec92d082 | 751 | plist_for_each_entry_safe(this, next, head, list) { |
1da177e4 | 752 | if (match_futex (&this->key, &key)) { |
ed6f7b10 IM |
753 | if (this->pi_state) { |
754 | ret = -EINVAL; | |
755 | break; | |
756 | } | |
cd689985 TG |
757 | |
758 | /* Check if one of the bits is set in both bitsets */ | |
759 | if (!(this->bitset & bitset)) | |
760 | continue; | |
761 | ||
1da177e4 LT |
762 | wake_futex(this); |
763 | if (++ret >= nr_wake) | |
764 | break; | |
765 | } | |
766 | } | |
767 | ||
e2970f2f | 768 | spin_unlock(&hb->lock); |
1da177e4 | 769 | out: |
36cf3b5c | 770 | futex_unlock_mm(fshared); |
1da177e4 LT |
771 | return ret; |
772 | } | |
773 | ||
4732efbe JJ |
774 | /* |
775 | * Wake up all waiters hashed on the physical page that is mapped | |
776 | * to this virtual address: | |
777 | */ | |
e2970f2f | 778 | static int |
34f01cc1 ED |
779 | futex_wake_op(u32 __user *uaddr1, struct rw_semaphore *fshared, |
780 | u32 __user *uaddr2, | |
e2970f2f | 781 | int nr_wake, int nr_wake2, int op) |
4732efbe JJ |
782 | { |
783 | union futex_key key1, key2; | |
e2970f2f | 784 | struct futex_hash_bucket *hb1, *hb2; |
ec92d082 | 785 | struct plist_head *head; |
4732efbe JJ |
786 | struct futex_q *this, *next; |
787 | int ret, op_ret, attempt = 0; | |
788 | ||
789 | retryfull: | |
36cf3b5c | 790 | futex_lock_mm(fshared); |
4732efbe | 791 | |
34f01cc1 | 792 | ret = get_futex_key(uaddr1, fshared, &key1); |
4732efbe JJ |
793 | if (unlikely(ret != 0)) |
794 | goto out; | |
34f01cc1 | 795 | ret = get_futex_key(uaddr2, fshared, &key2); |
4732efbe JJ |
796 | if (unlikely(ret != 0)) |
797 | goto out; | |
798 | ||
e2970f2f IM |
799 | hb1 = hash_futex(&key1); |
800 | hb2 = hash_futex(&key2); | |
4732efbe JJ |
801 | |
802 | retry: | |
8b8f319f | 803 | double_lock_hb(hb1, hb2); |
4732efbe | 804 | |
e2970f2f | 805 | op_ret = futex_atomic_op_inuser(op, uaddr2); |
4732efbe | 806 | if (unlikely(op_ret < 0)) { |
e2970f2f | 807 | u32 dummy; |
4732efbe | 808 | |
e2970f2f IM |
809 | spin_unlock(&hb1->lock); |
810 | if (hb1 != hb2) | |
811 | spin_unlock(&hb2->lock); | |
4732efbe | 812 | |
7ee1dd3f | 813 | #ifndef CONFIG_MMU |
e2970f2f IM |
814 | /* |
815 | * we don't get EFAULT from MMU faults if we don't have an MMU, | |
816 | * but we might get them from range checking | |
817 | */ | |
7ee1dd3f DH |
818 | ret = op_ret; |
819 | goto out; | |
820 | #endif | |
821 | ||
796f8d9b DG |
822 | if (unlikely(op_ret != -EFAULT)) { |
823 | ret = op_ret; | |
824 | goto out; | |
825 | } | |
826 | ||
e2970f2f IM |
827 | /* |
828 | * futex_atomic_op_inuser needs to both read and write | |
4732efbe JJ |
829 | * *(int __user *)uaddr2, but we can't modify it |
830 | * non-atomically. Therefore, if get_user below is not | |
831 | * enough, we need to handle the fault ourselves, while | |
e2970f2f IM |
832 | * still holding the mmap_sem. |
833 | */ | |
4732efbe | 834 | if (attempt++) { |
34f01cc1 | 835 | ret = futex_handle_fault((unsigned long)uaddr2, |
36cf3b5c | 836 | fshared, attempt); |
34f01cc1 | 837 | if (ret) |
4732efbe | 838 | goto out; |
4732efbe JJ |
839 | goto retry; |
840 | } | |
841 | ||
e2970f2f IM |
842 | /* |
843 | * If we would have faulted, release mmap_sem, | |
844 | * fault it in and start all over again. | |
845 | */ | |
36cf3b5c | 846 | futex_unlock_mm(fshared); |
4732efbe | 847 | |
e2970f2f | 848 | ret = get_user(dummy, uaddr2); |
4732efbe JJ |
849 | if (ret) |
850 | return ret; | |
851 | ||
852 | goto retryfull; | |
853 | } | |
854 | ||
e2970f2f | 855 | head = &hb1->chain; |
4732efbe | 856 | |
ec92d082 | 857 | plist_for_each_entry_safe(this, next, head, list) { |
4732efbe JJ |
858 | if (match_futex (&this->key, &key1)) { |
859 | wake_futex(this); | |
860 | if (++ret >= nr_wake) | |
861 | break; | |
862 | } | |
863 | } | |
864 | ||
865 | if (op_ret > 0) { | |
e2970f2f | 866 | head = &hb2->chain; |
4732efbe JJ |
867 | |
868 | op_ret = 0; | |
ec92d082 | 869 | plist_for_each_entry_safe(this, next, head, list) { |
4732efbe JJ |
870 | if (match_futex (&this->key, &key2)) { |
871 | wake_futex(this); | |
872 | if (++op_ret >= nr_wake2) | |
873 | break; | |
874 | } | |
875 | } | |
876 | ret += op_ret; | |
877 | } | |
878 | ||
e2970f2f IM |
879 | spin_unlock(&hb1->lock); |
880 | if (hb1 != hb2) | |
881 | spin_unlock(&hb2->lock); | |
4732efbe | 882 | out: |
36cf3b5c TG |
883 | futex_unlock_mm(fshared); |
884 | ||
4732efbe JJ |
885 | return ret; |
886 | } | |
887 | ||
1da177e4 LT |
888 | /* |
889 | * Requeue all waiters hashed on one physical page to another | |
890 | * physical page. | |
891 | */ | |
34f01cc1 ED |
892 | static int futex_requeue(u32 __user *uaddr1, struct rw_semaphore *fshared, |
893 | u32 __user *uaddr2, | |
e2970f2f | 894 | int nr_wake, int nr_requeue, u32 *cmpval) |
1da177e4 LT |
895 | { |
896 | union futex_key key1, key2; | |
e2970f2f | 897 | struct futex_hash_bucket *hb1, *hb2; |
ec92d082 | 898 | struct plist_head *head1; |
1da177e4 LT |
899 | struct futex_q *this, *next; |
900 | int ret, drop_count = 0; | |
901 | ||
902 | retry: | |
36cf3b5c | 903 | futex_lock_mm(fshared); |
1da177e4 | 904 | |
34f01cc1 | 905 | ret = get_futex_key(uaddr1, fshared, &key1); |
1da177e4 LT |
906 | if (unlikely(ret != 0)) |
907 | goto out; | |
34f01cc1 | 908 | ret = get_futex_key(uaddr2, fshared, &key2); |
1da177e4 LT |
909 | if (unlikely(ret != 0)) |
910 | goto out; | |
911 | ||
e2970f2f IM |
912 | hb1 = hash_futex(&key1); |
913 | hb2 = hash_futex(&key2); | |
1da177e4 | 914 | |
8b8f319f | 915 | double_lock_hb(hb1, hb2); |
1da177e4 | 916 | |
e2970f2f IM |
917 | if (likely(cmpval != NULL)) { |
918 | u32 curval; | |
1da177e4 | 919 | |
e2970f2f | 920 | ret = get_futex_value_locked(&curval, uaddr1); |
1da177e4 LT |
921 | |
922 | if (unlikely(ret)) { | |
e2970f2f IM |
923 | spin_unlock(&hb1->lock); |
924 | if (hb1 != hb2) | |
925 | spin_unlock(&hb2->lock); | |
1da177e4 | 926 | |
e2970f2f IM |
927 | /* |
928 | * If we would have faulted, release mmap_sem, fault | |
1da177e4 LT |
929 | * it in and start all over again. |
930 | */ | |
36cf3b5c | 931 | futex_unlock_mm(fshared); |
1da177e4 | 932 | |
e2970f2f | 933 | ret = get_user(curval, uaddr1); |
1da177e4 LT |
934 | |
935 | if (!ret) | |
936 | goto retry; | |
937 | ||
938 | return ret; | |
939 | } | |
e2970f2f | 940 | if (curval != *cmpval) { |
1da177e4 LT |
941 | ret = -EAGAIN; |
942 | goto out_unlock; | |
943 | } | |
944 | } | |
945 | ||
e2970f2f | 946 | head1 = &hb1->chain; |
ec92d082 | 947 | plist_for_each_entry_safe(this, next, head1, list) { |
1da177e4 LT |
948 | if (!match_futex (&this->key, &key1)) |
949 | continue; | |
950 | if (++ret <= nr_wake) { | |
951 | wake_futex(this); | |
952 | } else { | |
59e0e0ac SD |
953 | /* |
954 | * If key1 and key2 hash to the same bucket, no need to | |
955 | * requeue. | |
956 | */ | |
957 | if (likely(head1 != &hb2->chain)) { | |
ec92d082 PP |
958 | plist_del(&this->list, &hb1->chain); |
959 | plist_add(&this->list, &hb2->chain); | |
59e0e0ac | 960 | this->lock_ptr = &hb2->lock; |
ec92d082 PP |
961 | #ifdef CONFIG_DEBUG_PI_LIST |
962 | this->list.plist.lock = &hb2->lock; | |
963 | #endif | |
778e9a9c | 964 | } |
1da177e4 | 965 | this->key = key2; |
9adef58b | 966 | get_futex_key_refs(&key2); |
1da177e4 LT |
967 | drop_count++; |
968 | ||
969 | if (ret - nr_wake >= nr_requeue) | |
970 | break; | |
1da177e4 LT |
971 | } |
972 | } | |
973 | ||
974 | out_unlock: | |
e2970f2f IM |
975 | spin_unlock(&hb1->lock); |
976 | if (hb1 != hb2) | |
977 | spin_unlock(&hb2->lock); | |
1da177e4 | 978 | |
9adef58b | 979 | /* drop_futex_key_refs() must be called outside the spinlocks. */ |
1da177e4 | 980 | while (--drop_count >= 0) |
9adef58b | 981 | drop_futex_key_refs(&key1); |
1da177e4 LT |
982 | |
983 | out: | |
36cf3b5c | 984 | futex_unlock_mm(fshared); |
1da177e4 LT |
985 | return ret; |
986 | } | |
987 | ||
988 | /* The key must be already stored in q->key. */ | |
82af7aca | 989 | static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) |
1da177e4 | 990 | { |
e2970f2f | 991 | struct futex_hash_bucket *hb; |
1da177e4 | 992 | |
1da177e4 LT |
993 | init_waitqueue_head(&q->waiters); |
994 | ||
9adef58b | 995 | get_futex_key_refs(&q->key); |
e2970f2f IM |
996 | hb = hash_futex(&q->key); |
997 | q->lock_ptr = &hb->lock; | |
1da177e4 | 998 | |
e2970f2f IM |
999 | spin_lock(&hb->lock); |
1000 | return hb; | |
1da177e4 LT |
1001 | } |
1002 | ||
82af7aca | 1003 | static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) |
1da177e4 | 1004 | { |
ec92d082 PP |
1005 | int prio; |
1006 | ||
1007 | /* | |
1008 | * The priority used to register this element is | |
1009 | * - either the real thread-priority for the real-time threads | |
1010 | * (i.e. threads with a priority lower than MAX_RT_PRIO) | |
1011 | * - or MAX_RT_PRIO for non-RT threads. | |
1012 | * Thus, all RT-threads are woken first in priority order, and | |
1013 | * the others are woken last, in FIFO order. | |
1014 | */ | |
1015 | prio = min(current->normal_prio, MAX_RT_PRIO); | |
1016 | ||
1017 | plist_node_init(&q->list, prio); | |
1018 | #ifdef CONFIG_DEBUG_PI_LIST | |
1019 | q->list.plist.lock = &hb->lock; | |
1020 | #endif | |
1021 | plist_add(&q->list, &hb->chain); | |
c87e2837 | 1022 | q->task = current; |
e2970f2f | 1023 | spin_unlock(&hb->lock); |
1da177e4 LT |
1024 | } |
1025 | ||
1026 | static inline void | |
e2970f2f | 1027 | queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb) |
1da177e4 | 1028 | { |
e2970f2f | 1029 | spin_unlock(&hb->lock); |
9adef58b | 1030 | drop_futex_key_refs(&q->key); |
1da177e4 LT |
1031 | } |
1032 | ||
1033 | /* | |
1034 | * queue_me and unqueue_me must be called as a pair, each | |
1035 | * exactly once. They are called with the hashed spinlock held. | |
1036 | */ | |
1037 | ||
1da177e4 LT |
1038 | /* Return 1 if we were still queued (ie. 0 means we were woken) */ |
1039 | static int unqueue_me(struct futex_q *q) | |
1040 | { | |
1da177e4 | 1041 | spinlock_t *lock_ptr; |
e2970f2f | 1042 | int ret = 0; |
1da177e4 LT |
1043 | |
1044 | /* In the common case we don't take the spinlock, which is nice. */ | |
1045 | retry: | |
1046 | lock_ptr = q->lock_ptr; | |
e91467ec | 1047 | barrier(); |
c80544dc | 1048 | if (lock_ptr != NULL) { |
1da177e4 LT |
1049 | spin_lock(lock_ptr); |
1050 | /* | |
1051 | * q->lock_ptr can change between reading it and | |
1052 | * spin_lock(), causing us to take the wrong lock. This | |
1053 | * corrects the race condition. | |
1054 | * | |
1055 | * Reasoning goes like this: if we have the wrong lock, | |
1056 | * q->lock_ptr must have changed (maybe several times) | |
1057 | * between reading it and the spin_lock(). It can | |
1058 | * change again after the spin_lock() but only if it was | |
1059 | * already changed before the spin_lock(). It cannot, | |
1060 | * however, change back to the original value. Therefore | |
1061 | * we can detect whether we acquired the correct lock. | |
1062 | */ | |
1063 | if (unlikely(lock_ptr != q->lock_ptr)) { | |
1064 | spin_unlock(lock_ptr); | |
1065 | goto retry; | |
1066 | } | |
ec92d082 PP |
1067 | WARN_ON(plist_node_empty(&q->list)); |
1068 | plist_del(&q->list, &q->list.plist); | |
c87e2837 IM |
1069 | |
1070 | BUG_ON(q->pi_state); | |
1071 | ||
1da177e4 LT |
1072 | spin_unlock(lock_ptr); |
1073 | ret = 1; | |
1074 | } | |
1075 | ||
9adef58b | 1076 | drop_futex_key_refs(&q->key); |
1da177e4 LT |
1077 | return ret; |
1078 | } | |
1079 | ||
c87e2837 IM |
1080 | /* |
1081 | * PI futexes can not be requeued and must remove themself from the | |
d0aa7a70 PP |
1082 | * hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry |
1083 | * and dropped here. | |
c87e2837 | 1084 | */ |
d0aa7a70 | 1085 | static void unqueue_me_pi(struct futex_q *q) |
c87e2837 | 1086 | { |
ec92d082 PP |
1087 | WARN_ON(plist_node_empty(&q->list)); |
1088 | plist_del(&q->list, &q->list.plist); | |
c87e2837 IM |
1089 | |
1090 | BUG_ON(!q->pi_state); | |
1091 | free_pi_state(q->pi_state); | |
1092 | q->pi_state = NULL; | |
1093 | ||
d0aa7a70 | 1094 | spin_unlock(q->lock_ptr); |
c87e2837 | 1095 | |
9adef58b | 1096 | drop_futex_key_refs(&q->key); |
c87e2837 IM |
1097 | } |
1098 | ||
d0aa7a70 | 1099 | /* |
cdf71a10 | 1100 | * Fixup the pi_state owner with the new owner. |
d0aa7a70 | 1101 | * |
778e9a9c AK |
1102 | * Must be called with hash bucket lock held and mm->sem held for non |
1103 | * private futexes. | |
d0aa7a70 | 1104 | */ |
778e9a9c | 1105 | static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, |
1b7558e4 TG |
1106 | struct task_struct *newowner, |
1107 | struct rw_semaphore *fshared) | |
d0aa7a70 | 1108 | { |
cdf71a10 | 1109 | u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS; |
d0aa7a70 | 1110 | struct futex_pi_state *pi_state = q->pi_state; |
1b7558e4 | 1111 | struct task_struct *oldowner = pi_state->owner; |
d0aa7a70 | 1112 | u32 uval, curval, newval; |
1b7558e4 | 1113 | int ret, attempt = 0; |
d0aa7a70 PP |
1114 | |
1115 | /* Owner died? */ | |
1b7558e4 TG |
1116 | if (!pi_state->owner) |
1117 | newtid |= FUTEX_OWNER_DIED; | |
1118 | ||
1119 | /* | |
1120 | * We are here either because we stole the rtmutex from the | |
1121 | * pending owner or we are the pending owner which failed to | |
1122 | * get the rtmutex. We have to replace the pending owner TID | |
1123 | * in the user space variable. This must be atomic as we have | |
1124 | * to preserve the owner died bit here. | |
1125 | * | |
1126 | * Note: We write the user space value _before_ changing the | |
1127 | * pi_state because we can fault here. Imagine swapped out | |
1128 | * pages or a fork, which was running right before we acquired | |
1129 | * mmap_sem, that marked all the anonymous memory readonly for | |
1130 | * cow. | |
1131 | * | |
1132 | * Modifying pi_state _before_ the user space value would | |
1133 | * leave the pi_state in an inconsistent state when we fault | |
1134 | * here, because we need to drop the hash bucket lock to | |
1135 | * handle the fault. This might be observed in the PID check | |
1136 | * in lookup_pi_state. | |
1137 | */ | |
1138 | retry: | |
1139 | if (get_futex_value_locked(&uval, uaddr)) | |
1140 | goto handle_fault; | |
1141 | ||
1142 | while (1) { | |
1143 | newval = (uval & FUTEX_OWNER_DIED) | newtid; | |
1144 | ||
1145 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); | |
1146 | ||
1147 | if (curval == -EFAULT) | |
1148 | goto handle_fault; | |
1149 | if (curval == uval) | |
1150 | break; | |
1151 | uval = curval; | |
1152 | } | |
1153 | ||
1154 | /* | |
1155 | * We fixed up user space. Now we need to fix the pi_state | |
1156 | * itself. | |
1157 | */ | |
d0aa7a70 PP |
1158 | if (pi_state->owner != NULL) { |
1159 | spin_lock_irq(&pi_state->owner->pi_lock); | |
1160 | WARN_ON(list_empty(&pi_state->list)); | |
1161 | list_del_init(&pi_state->list); | |
1162 | spin_unlock_irq(&pi_state->owner->pi_lock); | |
1b7558e4 | 1163 | } |
d0aa7a70 | 1164 | |
cdf71a10 | 1165 | pi_state->owner = newowner; |
d0aa7a70 | 1166 | |
cdf71a10 | 1167 | spin_lock_irq(&newowner->pi_lock); |
d0aa7a70 | 1168 | WARN_ON(!list_empty(&pi_state->list)); |
cdf71a10 TG |
1169 | list_add(&pi_state->list, &newowner->pi_state_list); |
1170 | spin_unlock_irq(&newowner->pi_lock); | |
1b7558e4 | 1171 | return 0; |
d0aa7a70 | 1172 | |
d0aa7a70 | 1173 | /* |
1b7558e4 TG |
1174 | * To handle the page fault we need to drop the hash bucket |
1175 | * lock here. That gives the other task (either the pending | |
1176 | * owner itself or the task which stole the rtmutex) the | |
1177 | * chance to try the fixup of the pi_state. So once we are | |
1178 | * back from handling the fault we need to check the pi_state | |
1179 | * after reacquiring the hash bucket lock and before trying to | |
1180 | * do another fixup. When the fixup has been done already we | |
1181 | * simply return. | |
d0aa7a70 | 1182 | */ |
1b7558e4 TG |
1183 | handle_fault: |
1184 | spin_unlock(q->lock_ptr); | |
778e9a9c | 1185 | |
1b7558e4 | 1186 | ret = futex_handle_fault((unsigned long)uaddr, fshared, attempt++); |
778e9a9c | 1187 | |
1b7558e4 | 1188 | spin_lock(q->lock_ptr); |
778e9a9c | 1189 | |
1b7558e4 TG |
1190 | /* |
1191 | * Check if someone else fixed it for us: | |
1192 | */ | |
1193 | if (pi_state->owner != oldowner) | |
1194 | return 0; | |
1195 | ||
1196 | if (ret) | |
1197 | return ret; | |
1198 | ||
1199 | goto retry; | |
d0aa7a70 PP |
1200 | } |
1201 | ||
34f01cc1 ED |
1202 | /* |
1203 | * In case we must use restart_block to restart a futex_wait, | |
ce6bd420 | 1204 | * we encode in the 'flags' shared capability |
34f01cc1 | 1205 | */ |
ce6bd420 | 1206 | #define FLAGS_SHARED 1 |
34f01cc1 | 1207 | |
72c1bbf3 | 1208 | static long futex_wait_restart(struct restart_block *restart); |
36cf3b5c | 1209 | |
34f01cc1 | 1210 | static int futex_wait(u32 __user *uaddr, struct rw_semaphore *fshared, |
cd689985 | 1211 | u32 val, ktime_t *abs_time, u32 bitset) |
1da177e4 | 1212 | { |
c87e2837 IM |
1213 | struct task_struct *curr = current; |
1214 | DECLARE_WAITQUEUE(wait, curr); | |
e2970f2f | 1215 | struct futex_hash_bucket *hb; |
1da177e4 | 1216 | struct futex_q q; |
e2970f2f IM |
1217 | u32 uval; |
1218 | int ret; | |
bd197234 | 1219 | struct hrtimer_sleeper t; |
c19384b5 | 1220 | int rem = 0; |
1da177e4 | 1221 | |
cd689985 TG |
1222 | if (!bitset) |
1223 | return -EINVAL; | |
1224 | ||
c87e2837 | 1225 | q.pi_state = NULL; |
cd689985 | 1226 | q.bitset = bitset; |
1da177e4 | 1227 | retry: |
36cf3b5c | 1228 | futex_lock_mm(fshared); |
1da177e4 | 1229 | |
34f01cc1 | 1230 | ret = get_futex_key(uaddr, fshared, &q.key); |
1da177e4 LT |
1231 | if (unlikely(ret != 0)) |
1232 | goto out_release_sem; | |
1233 | ||
82af7aca | 1234 | hb = queue_lock(&q); |
1da177e4 LT |
1235 | |
1236 | /* | |
1237 | * Access the page AFTER the futex is queued. | |
1238 | * Order is important: | |
1239 | * | |
1240 | * Userspace waiter: val = var; if (cond(val)) futex_wait(&var, val); | |
1241 | * Userspace waker: if (cond(var)) { var = new; futex_wake(&var); } | |
1242 | * | |
1243 | * The basic logical guarantee of a futex is that it blocks ONLY | |
1244 | * if cond(var) is known to be true at the time of blocking, for | |
1245 | * any cond. If we queued after testing *uaddr, that would open | |
1246 | * a race condition where we could block indefinitely with | |
1247 | * cond(var) false, which would violate the guarantee. | |
1248 | * | |
1249 | * A consequence is that futex_wait() can return zero and absorb | |
1250 | * a wakeup when *uaddr != val on entry to the syscall. This is | |
1251 | * rare, but normal. | |
1252 | * | |
34f01cc1 ED |
1253 | * for shared futexes, we hold the mmap semaphore, so the mapping |
1254 | * cannot have changed since we looked it up in get_futex_key. | |
1da177e4 | 1255 | */ |
e2970f2f | 1256 | ret = get_futex_value_locked(&uval, uaddr); |
1da177e4 LT |
1257 | |
1258 | if (unlikely(ret)) { | |
e2970f2f | 1259 | queue_unlock(&q, hb); |
1da177e4 | 1260 | |
e2970f2f IM |
1261 | /* |
1262 | * If we would have faulted, release mmap_sem, fault it in and | |
1da177e4 LT |
1263 | * start all over again. |
1264 | */ | |
36cf3b5c | 1265 | futex_unlock_mm(fshared); |
1da177e4 | 1266 | |
e2970f2f | 1267 | ret = get_user(uval, uaddr); |
1da177e4 LT |
1268 | |
1269 | if (!ret) | |
1270 | goto retry; | |
1271 | return ret; | |
1272 | } | |
c87e2837 IM |
1273 | ret = -EWOULDBLOCK; |
1274 | if (uval != val) | |
1275 | goto out_unlock_release_sem; | |
1da177e4 LT |
1276 | |
1277 | /* Only actually queue if *uaddr contained val. */ | |
82af7aca | 1278 | queue_me(&q, hb); |
1da177e4 LT |
1279 | |
1280 | /* | |
1281 | * Now the futex is queued and we have checked the data, we | |
1282 | * don't want to hold mmap_sem while we sleep. | |
c87e2837 | 1283 | */ |
36cf3b5c | 1284 | futex_unlock_mm(fshared); |
1da177e4 LT |
1285 | |
1286 | /* | |
1287 | * There might have been scheduling since the queue_me(), as we | |
1288 | * cannot hold a spinlock across the get_user() in case it | |
1289 | * faults, and we cannot just set TASK_INTERRUPTIBLE state when | |
1290 | * queueing ourselves into the futex hash. This code thus has to | |
1291 | * rely on the futex_wake() code removing us from hash when it | |
1292 | * wakes us up. | |
1293 | */ | |
1294 | ||
1295 | /* add_wait_queue is the barrier after __set_current_state. */ | |
1296 | __set_current_state(TASK_INTERRUPTIBLE); | |
1297 | add_wait_queue(&q.waiters, &wait); | |
1298 | /* | |
ec92d082 | 1299 | * !plist_node_empty() is safe here without any lock. |
1da177e4 LT |
1300 | * q.lock_ptr != 0 is not safe, because of ordering against wakeup. |
1301 | */ | |
ec92d082 | 1302 | if (likely(!plist_node_empty(&q.list))) { |
c19384b5 PP |
1303 | if (!abs_time) |
1304 | schedule(); | |
1305 | else { | |
ae4b748e AV |
1306 | unsigned long slack; |
1307 | slack = current->timer_slack_ns; | |
1308 | if (rt_task(current)) | |
1309 | slack = 0; | |
237fc6e7 TG |
1310 | hrtimer_init_on_stack(&t.timer, CLOCK_MONOTONIC, |
1311 | HRTIMER_MODE_ABS); | |
c19384b5 | 1312 | hrtimer_init_sleeper(&t, current); |
ae4b748e | 1313 | hrtimer_set_expires_range_ns(&t.timer, *abs_time, slack); |
c19384b5 | 1314 | |
cc584b21 | 1315 | hrtimer_start_expires(&t.timer, HRTIMER_MODE_ABS); |
3588a085 PZ |
1316 | if (!hrtimer_active(&t.timer)) |
1317 | t.task = NULL; | |
c19384b5 PP |
1318 | |
1319 | /* | |
1320 | * the timer could have already expired, in which | |
1321 | * case current would be flagged for rescheduling. | |
1322 | * Don't bother calling schedule. | |
1323 | */ | |
1324 | if (likely(t.task)) | |
1325 | schedule(); | |
1326 | ||
1327 | hrtimer_cancel(&t.timer); | |
72c1bbf3 | 1328 | |
c19384b5 PP |
1329 | /* Flag if a timeout occured */ |
1330 | rem = (t.task == NULL); | |
237fc6e7 TG |
1331 | |
1332 | destroy_hrtimer_on_stack(&t.timer); | |
c19384b5 | 1333 | } |
72c1bbf3 | 1334 | } |
1da177e4 LT |
1335 | __set_current_state(TASK_RUNNING); |
1336 | ||
1337 | /* | |
1338 | * NOTE: we don't remove ourselves from the waitqueue because | |
1339 | * we are the only user of it. | |
1340 | */ | |
1341 | ||
1342 | /* If we were woken (and unqueued), we succeeded, whatever. */ | |
1343 | if (!unqueue_me(&q)) | |
1344 | return 0; | |
c19384b5 | 1345 | if (rem) |
1da177e4 | 1346 | return -ETIMEDOUT; |
72c1bbf3 | 1347 | |
e2970f2f IM |
1348 | /* |
1349 | * We expect signal_pending(current), but another thread may | |
1350 | * have handled it for us already. | |
1351 | */ | |
c19384b5 | 1352 | if (!abs_time) |
72c1bbf3 NP |
1353 | return -ERESTARTSYS; |
1354 | else { | |
1355 | struct restart_block *restart; | |
1356 | restart = ¤t_thread_info()->restart_block; | |
1357 | restart->fn = futex_wait_restart; | |
ce6bd420 SR |
1358 | restart->futex.uaddr = (u32 *)uaddr; |
1359 | restart->futex.val = val; | |
1360 | restart->futex.time = abs_time->tv64; | |
cd689985 | 1361 | restart->futex.bitset = bitset; |
ce6bd420 SR |
1362 | restart->futex.flags = 0; |
1363 | ||
34f01cc1 | 1364 | if (fshared) |
ce6bd420 | 1365 | restart->futex.flags |= FLAGS_SHARED; |
72c1bbf3 NP |
1366 | return -ERESTART_RESTARTBLOCK; |
1367 | } | |
1da177e4 | 1368 | |
c87e2837 IM |
1369 | out_unlock_release_sem: |
1370 | queue_unlock(&q, hb); | |
1371 | ||
1da177e4 | 1372 | out_release_sem: |
36cf3b5c | 1373 | futex_unlock_mm(fshared); |
c87e2837 IM |
1374 | return ret; |
1375 | } | |
1376 | ||
72c1bbf3 NP |
1377 | |
1378 | static long futex_wait_restart(struct restart_block *restart) | |
1379 | { | |
ce6bd420 | 1380 | u32 __user *uaddr = (u32 __user *)restart->futex.uaddr; |
34f01cc1 | 1381 | struct rw_semaphore *fshared = NULL; |
ce6bd420 | 1382 | ktime_t t; |
72c1bbf3 | 1383 | |
ce6bd420 | 1384 | t.tv64 = restart->futex.time; |
72c1bbf3 | 1385 | restart->fn = do_no_restart_syscall; |
ce6bd420 | 1386 | if (restart->futex.flags & FLAGS_SHARED) |
34f01cc1 | 1387 | fshared = ¤t->mm->mmap_sem; |
cd689985 TG |
1388 | return (long)futex_wait(uaddr, fshared, restart->futex.val, &t, |
1389 | restart->futex.bitset); | |
72c1bbf3 NP |
1390 | } |
1391 | ||
1392 | ||
c87e2837 IM |
1393 | /* |
1394 | * Userspace tried a 0 -> TID atomic transition of the futex value | |
1395 | * and failed. The kernel side here does the whole locking operation: | |
1396 | * if there are waiters then it will block, it does PI, etc. (Due to | |
1397 | * races the kernel might see a 0 value of the futex too.) | |
1398 | */ | |
34f01cc1 ED |
1399 | static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared, |
1400 | int detect, ktime_t *time, int trylock) | |
c87e2837 | 1401 | { |
c5780e97 | 1402 | struct hrtimer_sleeper timeout, *to = NULL; |
c87e2837 IM |
1403 | struct task_struct *curr = current; |
1404 | struct futex_hash_bucket *hb; | |
1405 | u32 uval, newval, curval; | |
1406 | struct futex_q q; | |
778e9a9c | 1407 | int ret, lock_taken, ownerdied = 0, attempt = 0; |
c87e2837 IM |
1408 | |
1409 | if (refill_pi_state_cache()) | |
1410 | return -ENOMEM; | |
1411 | ||
c19384b5 | 1412 | if (time) { |
c5780e97 | 1413 | to = &timeout; |
237fc6e7 TG |
1414 | hrtimer_init_on_stack(&to->timer, CLOCK_REALTIME, |
1415 | HRTIMER_MODE_ABS); | |
c5780e97 | 1416 | hrtimer_init_sleeper(to, current); |
cc584b21 | 1417 | hrtimer_set_expires(&to->timer, *time); |
c5780e97 TG |
1418 | } |
1419 | ||
c87e2837 IM |
1420 | q.pi_state = NULL; |
1421 | retry: | |
36cf3b5c | 1422 | futex_lock_mm(fshared); |
c87e2837 | 1423 | |
34f01cc1 | 1424 | ret = get_futex_key(uaddr, fshared, &q.key); |
c87e2837 IM |
1425 | if (unlikely(ret != 0)) |
1426 | goto out_release_sem; | |
1427 | ||
778e9a9c | 1428 | retry_unlocked: |
82af7aca | 1429 | hb = queue_lock(&q); |
c87e2837 IM |
1430 | |
1431 | retry_locked: | |
778e9a9c | 1432 | ret = lock_taken = 0; |
d0aa7a70 | 1433 | |
c87e2837 IM |
1434 | /* |
1435 | * To avoid races, we attempt to take the lock here again | |
1436 | * (by doing a 0 -> TID atomic cmpxchg), while holding all | |
1437 | * the locks. It will most likely not succeed. | |
1438 | */ | |
b488893a | 1439 | newval = task_pid_vnr(current); |
c87e2837 | 1440 | |
36cf3b5c | 1441 | curval = cmpxchg_futex_value_locked(uaddr, 0, newval); |
c87e2837 IM |
1442 | |
1443 | if (unlikely(curval == -EFAULT)) | |
1444 | goto uaddr_faulted; | |
1445 | ||
778e9a9c AK |
1446 | /* |
1447 | * Detect deadlocks. In case of REQUEUE_PI this is a valid | |
1448 | * situation and we return success to user space. | |
1449 | */ | |
b488893a | 1450 | if (unlikely((curval & FUTEX_TID_MASK) == task_pid_vnr(current))) { |
bd197234 | 1451 | ret = -EDEADLK; |
c87e2837 IM |
1452 | goto out_unlock_release_sem; |
1453 | } | |
1454 | ||
1455 | /* | |
778e9a9c | 1456 | * Surprise - we got the lock. Just return to userspace: |
c87e2837 IM |
1457 | */ |
1458 | if (unlikely(!curval)) | |
1459 | goto out_unlock_release_sem; | |
1460 | ||
1461 | uval = curval; | |
778e9a9c | 1462 | |
d0aa7a70 | 1463 | /* |
778e9a9c AK |
1464 | * Set the WAITERS flag, so the owner will know it has someone |
1465 | * to wake at next unlock | |
d0aa7a70 | 1466 | */ |
778e9a9c AK |
1467 | newval = curval | FUTEX_WAITERS; |
1468 | ||
1469 | /* | |
1470 | * There are two cases, where a futex might have no owner (the | |
bd197234 TG |
1471 | * owner TID is 0): OWNER_DIED. We take over the futex in this |
1472 | * case. We also do an unconditional take over, when the owner | |
1473 | * of the futex died. | |
778e9a9c AK |
1474 | * |
1475 | * This is safe as we are protected by the hash bucket lock ! | |
1476 | */ | |
1477 | if (unlikely(ownerdied || !(curval & FUTEX_TID_MASK))) { | |
bd197234 | 1478 | /* Keep the OWNER_DIED bit */ |
b488893a | 1479 | newval = (curval & ~FUTEX_TID_MASK) | task_pid_vnr(current); |
778e9a9c AK |
1480 | ownerdied = 0; |
1481 | lock_taken = 1; | |
1482 | } | |
c87e2837 | 1483 | |
36cf3b5c | 1484 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
c87e2837 IM |
1485 | |
1486 | if (unlikely(curval == -EFAULT)) | |
1487 | goto uaddr_faulted; | |
1488 | if (unlikely(curval != uval)) | |
1489 | goto retry_locked; | |
1490 | ||
778e9a9c | 1491 | /* |
bd197234 | 1492 | * We took the lock due to owner died take over. |
778e9a9c | 1493 | */ |
bd197234 | 1494 | if (unlikely(lock_taken)) |
d0aa7a70 | 1495 | goto out_unlock_release_sem; |
d0aa7a70 | 1496 | |
c87e2837 IM |
1497 | /* |
1498 | * We dont have the lock. Look up the PI state (or create it if | |
1499 | * we are the first waiter): | |
1500 | */ | |
d0aa7a70 | 1501 | ret = lookup_pi_state(uval, hb, &q.key, &q.pi_state); |
c87e2837 IM |
1502 | |
1503 | if (unlikely(ret)) { | |
778e9a9c | 1504 | switch (ret) { |
c87e2837 | 1505 | |
778e9a9c AK |
1506 | case -EAGAIN: |
1507 | /* | |
1508 | * Task is exiting and we just wait for the | |
1509 | * exit to complete. | |
1510 | */ | |
1511 | queue_unlock(&q, hb); | |
36cf3b5c | 1512 | futex_unlock_mm(fshared); |
778e9a9c AK |
1513 | cond_resched(); |
1514 | goto retry; | |
c87e2837 | 1515 | |
778e9a9c AK |
1516 | case -ESRCH: |
1517 | /* | |
1518 | * No owner found for this futex. Check if the | |
1519 | * OWNER_DIED bit is set to figure out whether | |
1520 | * this is a robust futex or not. | |
1521 | */ | |
1522 | if (get_futex_value_locked(&curval, uaddr)) | |
c87e2837 | 1523 | goto uaddr_faulted; |
778e9a9c AK |
1524 | |
1525 | /* | |
1526 | * We simply start over in case of a robust | |
1527 | * futex. The code above will take the futex | |
1528 | * and return happy. | |
1529 | */ | |
1530 | if (curval & FUTEX_OWNER_DIED) { | |
1531 | ownerdied = 1; | |
c87e2837 | 1532 | goto retry_locked; |
778e9a9c AK |
1533 | } |
1534 | default: | |
1535 | goto out_unlock_release_sem; | |
c87e2837 | 1536 | } |
c87e2837 IM |
1537 | } |
1538 | ||
1539 | /* | |
1540 | * Only actually queue now that the atomic ops are done: | |
1541 | */ | |
82af7aca | 1542 | queue_me(&q, hb); |
c87e2837 IM |
1543 | |
1544 | /* | |
1545 | * Now the futex is queued and we have checked the data, we | |
1546 | * don't want to hold mmap_sem while we sleep. | |
1547 | */ | |
36cf3b5c | 1548 | futex_unlock_mm(fshared); |
c87e2837 IM |
1549 | |
1550 | WARN_ON(!q.pi_state); | |
1551 | /* | |
1552 | * Block on the PI mutex: | |
1553 | */ | |
1554 | if (!trylock) | |
1555 | ret = rt_mutex_timed_lock(&q.pi_state->pi_mutex, to, 1); | |
1556 | else { | |
1557 | ret = rt_mutex_trylock(&q.pi_state->pi_mutex); | |
1558 | /* Fixup the trylock return value: */ | |
1559 | ret = ret ? 0 : -EWOULDBLOCK; | |
1560 | } | |
1561 | ||
36cf3b5c | 1562 | futex_lock_mm(fshared); |
a99e4e41 | 1563 | spin_lock(q.lock_ptr); |
c87e2837 | 1564 | |
778e9a9c AK |
1565 | if (!ret) { |
1566 | /* | |
1567 | * Got the lock. We might not be the anticipated owner | |
1568 | * if we did a lock-steal - fix up the PI-state in | |
1569 | * that case: | |
1570 | */ | |
1571 | if (q.pi_state->owner != curr) | |
1b7558e4 | 1572 | ret = fixup_pi_state_owner(uaddr, &q, curr, fshared); |
778e9a9c | 1573 | } else { |
c87e2837 IM |
1574 | /* |
1575 | * Catch the rare case, where the lock was released | |
778e9a9c AK |
1576 | * when we were on the way back before we locked the |
1577 | * hash bucket. | |
c87e2837 | 1578 | */ |
cdf71a10 TG |
1579 | if (q.pi_state->owner == curr) { |
1580 | /* | |
1581 | * Try to get the rt_mutex now. This might | |
1582 | * fail as some other task acquired the | |
1583 | * rt_mutex after we removed ourself from the | |
1584 | * rt_mutex waiters list. | |
1585 | */ | |
1586 | if (rt_mutex_trylock(&q.pi_state->pi_mutex)) | |
1587 | ret = 0; | |
1588 | else { | |
1589 | /* | |
1590 | * pi_state is incorrect, some other | |
1591 | * task did a lock steal and we | |
1592 | * returned due to timeout or signal | |
1593 | * without taking the rt_mutex. Too | |
1594 | * late. We can access the | |
1595 | * rt_mutex_owner without locking, as | |
1596 | * the other task is now blocked on | |
1597 | * the hash bucket lock. Fix the state | |
1598 | * up. | |
1599 | */ | |
1600 | struct task_struct *owner; | |
1601 | int res; | |
1602 | ||
1603 | owner = rt_mutex_owner(&q.pi_state->pi_mutex); | |
1b7558e4 TG |
1604 | res = fixup_pi_state_owner(uaddr, &q, owner, |
1605 | fshared); | |
cdf71a10 | 1606 | |
cdf71a10 TG |
1607 | /* propagate -EFAULT, if the fixup failed */ |
1608 | if (res) | |
1609 | ret = res; | |
1610 | } | |
778e9a9c AK |
1611 | } else { |
1612 | /* | |
1613 | * Paranoia check. If we did not take the lock | |
1614 | * in the trylock above, then we should not be | |
1615 | * the owner of the rtmutex, neither the real | |
1616 | * nor the pending one: | |
1617 | */ | |
1618 | if (rt_mutex_owner(&q.pi_state->pi_mutex) == curr) | |
1619 | printk(KERN_ERR "futex_lock_pi: ret = %d " | |
1620 | "pi-mutex: %p pi-state %p\n", ret, | |
1621 | q.pi_state->pi_mutex.owner, | |
1622 | q.pi_state->owner); | |
c87e2837 | 1623 | } |
c87e2837 IM |
1624 | } |
1625 | ||
778e9a9c AK |
1626 | /* Unqueue and drop the lock */ |
1627 | unqueue_me_pi(&q); | |
36cf3b5c | 1628 | futex_unlock_mm(fshared); |
c87e2837 | 1629 | |
237fc6e7 TG |
1630 | if (to) |
1631 | destroy_hrtimer_on_stack(&to->timer); | |
c5780e97 | 1632 | return ret != -EINTR ? ret : -ERESTARTNOINTR; |
c87e2837 IM |
1633 | |
1634 | out_unlock_release_sem: | |
1635 | queue_unlock(&q, hb); | |
1636 | ||
1637 | out_release_sem: | |
36cf3b5c | 1638 | futex_unlock_mm(fshared); |
237fc6e7 TG |
1639 | if (to) |
1640 | destroy_hrtimer_on_stack(&to->timer); | |
c87e2837 IM |
1641 | return ret; |
1642 | ||
1643 | uaddr_faulted: | |
1644 | /* | |
1645 | * We have to r/w *(int __user *)uaddr, but we can't modify it | |
1646 | * non-atomically. Therefore, if get_user below is not | |
1647 | * enough, we need to handle the fault ourselves, while | |
1648 | * still holding the mmap_sem. | |
778e9a9c AK |
1649 | * |
1650 | * ... and hb->lock. :-) --ANK | |
c87e2837 | 1651 | */ |
778e9a9c AK |
1652 | queue_unlock(&q, hb); |
1653 | ||
c87e2837 | 1654 | if (attempt++) { |
34f01cc1 ED |
1655 | ret = futex_handle_fault((unsigned long)uaddr, fshared, |
1656 | attempt); | |
1657 | if (ret) | |
778e9a9c AK |
1658 | goto out_release_sem; |
1659 | goto retry_unlocked; | |
c87e2837 IM |
1660 | } |
1661 | ||
36cf3b5c | 1662 | futex_unlock_mm(fshared); |
c87e2837 IM |
1663 | |
1664 | ret = get_user(uval, uaddr); | |
1665 | if (!ret && (uval != -EFAULT)) | |
1666 | goto retry; | |
1667 | ||
237fc6e7 TG |
1668 | if (to) |
1669 | destroy_hrtimer_on_stack(&to->timer); | |
c87e2837 IM |
1670 | return ret; |
1671 | } | |
1672 | ||
c87e2837 IM |
1673 | /* |
1674 | * Userspace attempted a TID -> 0 atomic transition, and failed. | |
1675 | * This is the in-kernel slowpath: we look up the PI state (if any), | |
1676 | * and do the rt-mutex unlock. | |
1677 | */ | |
34f01cc1 | 1678 | static int futex_unlock_pi(u32 __user *uaddr, struct rw_semaphore *fshared) |
c87e2837 IM |
1679 | { |
1680 | struct futex_hash_bucket *hb; | |
1681 | struct futex_q *this, *next; | |
1682 | u32 uval; | |
ec92d082 | 1683 | struct plist_head *head; |
c87e2837 IM |
1684 | union futex_key key; |
1685 | int ret, attempt = 0; | |
1686 | ||
1687 | retry: | |
1688 | if (get_user(uval, uaddr)) | |
1689 | return -EFAULT; | |
1690 | /* | |
1691 | * We release only a lock we actually own: | |
1692 | */ | |
b488893a | 1693 | if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current)) |
c87e2837 IM |
1694 | return -EPERM; |
1695 | /* | |
1696 | * First take all the futex related locks: | |
1697 | */ | |
36cf3b5c | 1698 | futex_lock_mm(fshared); |
c87e2837 | 1699 | |
34f01cc1 | 1700 | ret = get_futex_key(uaddr, fshared, &key); |
c87e2837 IM |
1701 | if (unlikely(ret != 0)) |
1702 | goto out; | |
1703 | ||
1704 | hb = hash_futex(&key); | |
778e9a9c | 1705 | retry_unlocked: |
c87e2837 IM |
1706 | spin_lock(&hb->lock); |
1707 | ||
c87e2837 IM |
1708 | /* |
1709 | * To avoid races, try to do the TID -> 0 atomic transition | |
1710 | * again. If it succeeds then we can return without waking | |
1711 | * anyone else up: | |
1712 | */ | |
36cf3b5c | 1713 | if (!(uval & FUTEX_OWNER_DIED)) |
b488893a | 1714 | uval = cmpxchg_futex_value_locked(uaddr, task_pid_vnr(current), 0); |
36cf3b5c | 1715 | |
c87e2837 IM |
1716 | |
1717 | if (unlikely(uval == -EFAULT)) | |
1718 | goto pi_faulted; | |
1719 | /* | |
1720 | * Rare case: we managed to release the lock atomically, | |
1721 | * no need to wake anyone else up: | |
1722 | */ | |
b488893a | 1723 | if (unlikely(uval == task_pid_vnr(current))) |
c87e2837 IM |
1724 | goto out_unlock; |
1725 | ||
1726 | /* | |
1727 | * Ok, other tasks may need to be woken up - check waiters | |
1728 | * and do the wakeup if necessary: | |
1729 | */ | |
1730 | head = &hb->chain; | |
1731 | ||
ec92d082 | 1732 | plist_for_each_entry_safe(this, next, head, list) { |
c87e2837 IM |
1733 | if (!match_futex (&this->key, &key)) |
1734 | continue; | |
1735 | ret = wake_futex_pi(uaddr, uval, this); | |
1736 | /* | |
1737 | * The atomic access to the futex value | |
1738 | * generated a pagefault, so retry the | |
1739 | * user-access and the wakeup: | |
1740 | */ | |
1741 | if (ret == -EFAULT) | |
1742 | goto pi_faulted; | |
1743 | goto out_unlock; | |
1744 | } | |
1745 | /* | |
1746 | * No waiters - kernel unlocks the futex: | |
1747 | */ | |
e3f2ddea IM |
1748 | if (!(uval & FUTEX_OWNER_DIED)) { |
1749 | ret = unlock_futex_pi(uaddr, uval); | |
1750 | if (ret == -EFAULT) | |
1751 | goto pi_faulted; | |
1752 | } | |
c87e2837 IM |
1753 | |
1754 | out_unlock: | |
1755 | spin_unlock(&hb->lock); | |
1756 | out: | |
36cf3b5c | 1757 | futex_unlock_mm(fshared); |
c87e2837 IM |
1758 | |
1759 | return ret; | |
1760 | ||
1761 | pi_faulted: | |
1762 | /* | |
1763 | * We have to r/w *(int __user *)uaddr, but we can't modify it | |
1764 | * non-atomically. Therefore, if get_user below is not | |
1765 | * enough, we need to handle the fault ourselves, while | |
1766 | * still holding the mmap_sem. | |
778e9a9c AK |
1767 | * |
1768 | * ... and hb->lock. --ANK | |
c87e2837 | 1769 | */ |
778e9a9c AK |
1770 | spin_unlock(&hb->lock); |
1771 | ||
c87e2837 | 1772 | if (attempt++) { |
34f01cc1 ED |
1773 | ret = futex_handle_fault((unsigned long)uaddr, fshared, |
1774 | attempt); | |
1775 | if (ret) | |
778e9a9c | 1776 | goto out; |
187226f5 | 1777 | uval = 0; |
778e9a9c | 1778 | goto retry_unlocked; |
c87e2837 IM |
1779 | } |
1780 | ||
36cf3b5c | 1781 | futex_unlock_mm(fshared); |
c87e2837 IM |
1782 | |
1783 | ret = get_user(uval, uaddr); | |
1784 | if (!ret && (uval != -EFAULT)) | |
1785 | goto retry; | |
1786 | ||
1da177e4 LT |
1787 | return ret; |
1788 | } | |
1789 | ||
0771dfef IM |
1790 | /* |
1791 | * Support for robust futexes: the kernel cleans up held futexes at | |
1792 | * thread exit time. | |
1793 | * | |
1794 | * Implementation: user-space maintains a per-thread list of locks it | |
1795 | * is holding. Upon do_exit(), the kernel carefully walks this list, | |
1796 | * and marks all locks that are owned by this thread with the | |
c87e2837 | 1797 | * FUTEX_OWNER_DIED bit, and wakes up a waiter (if any). The list is |
0771dfef IM |
1798 | * always manipulated with the lock held, so the list is private and |
1799 | * per-thread. Userspace also maintains a per-thread 'list_op_pending' | |
1800 | * field, to allow the kernel to clean up if the thread dies after | |
1801 | * acquiring the lock, but just before it could have added itself to | |
1802 | * the list. There can only be one such pending lock. | |
1803 | */ | |
1804 | ||
1805 | /** | |
1806 | * sys_set_robust_list - set the robust-futex list head of a task | |
1807 | * @head: pointer to the list-head | |
1808 | * @len: length of the list-head, as userspace expects | |
1809 | */ | |
1810 | asmlinkage long | |
1811 | sys_set_robust_list(struct robust_list_head __user *head, | |
1812 | size_t len) | |
1813 | { | |
a0c1e907 TG |
1814 | if (!futex_cmpxchg_enabled) |
1815 | return -ENOSYS; | |
0771dfef IM |
1816 | /* |
1817 | * The kernel knows only one size for now: | |
1818 | */ | |
1819 | if (unlikely(len != sizeof(*head))) | |
1820 | return -EINVAL; | |
1821 | ||
1822 | current->robust_list = head; | |
1823 | ||
1824 | return 0; | |
1825 | } | |
1826 | ||
1827 | /** | |
1828 | * sys_get_robust_list - get the robust-futex list head of a task | |
1829 | * @pid: pid of the process [zero for current task] | |
1830 | * @head_ptr: pointer to a list-head pointer, the kernel fills it in | |
1831 | * @len_ptr: pointer to a length field, the kernel fills in the header size | |
1832 | */ | |
1833 | asmlinkage long | |
ba46df98 | 1834 | sys_get_robust_list(int pid, struct robust_list_head __user * __user *head_ptr, |
0771dfef IM |
1835 | size_t __user *len_ptr) |
1836 | { | |
ba46df98 | 1837 | struct robust_list_head __user *head; |
0771dfef | 1838 | unsigned long ret; |
c69e8d9c | 1839 | const struct cred *cred = current_cred(), *pcred; |
0771dfef | 1840 | |
a0c1e907 TG |
1841 | if (!futex_cmpxchg_enabled) |
1842 | return -ENOSYS; | |
1843 | ||
0771dfef IM |
1844 | if (!pid) |
1845 | head = current->robust_list; | |
1846 | else { | |
1847 | struct task_struct *p; | |
1848 | ||
1849 | ret = -ESRCH; | |
aaa2a97e | 1850 | rcu_read_lock(); |
228ebcbe | 1851 | p = find_task_by_vpid(pid); |
0771dfef IM |
1852 | if (!p) |
1853 | goto err_unlock; | |
1854 | ret = -EPERM; | |
c69e8d9c DH |
1855 | pcred = __task_cred(p); |
1856 | if (cred->euid != pcred->euid && | |
1857 | cred->euid != pcred->uid && | |
76aac0e9 | 1858 | !capable(CAP_SYS_PTRACE)) |
0771dfef IM |
1859 | goto err_unlock; |
1860 | head = p->robust_list; | |
aaa2a97e | 1861 | rcu_read_unlock(); |
0771dfef IM |
1862 | } |
1863 | ||
1864 | if (put_user(sizeof(*head), len_ptr)) | |
1865 | return -EFAULT; | |
1866 | return put_user(head, head_ptr); | |
1867 | ||
1868 | err_unlock: | |
aaa2a97e | 1869 | rcu_read_unlock(); |
0771dfef IM |
1870 | |
1871 | return ret; | |
1872 | } | |
1873 | ||
1874 | /* | |
1875 | * Process a futex-list entry, check whether it's owned by the | |
1876 | * dying task, and do notification if so: | |
1877 | */ | |
e3f2ddea | 1878 | int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi) |
0771dfef | 1879 | { |
e3f2ddea | 1880 | u32 uval, nval, mval; |
0771dfef | 1881 | |
8f17d3a5 IM |
1882 | retry: |
1883 | if (get_user(uval, uaddr)) | |
0771dfef IM |
1884 | return -1; |
1885 | ||
b488893a | 1886 | if ((uval & FUTEX_TID_MASK) == task_pid_vnr(curr)) { |
0771dfef IM |
1887 | /* |
1888 | * Ok, this dying thread is truly holding a futex | |
1889 | * of interest. Set the OWNER_DIED bit atomically | |
1890 | * via cmpxchg, and if the value had FUTEX_WAITERS | |
1891 | * set, wake up a waiter (if any). (We have to do a | |
1892 | * futex_wake() even if OWNER_DIED is already set - | |
1893 | * to handle the rare but possible case of recursive | |
1894 | * thread-death.) The rest of the cleanup is done in | |
1895 | * userspace. | |
1896 | */ | |
e3f2ddea IM |
1897 | mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; |
1898 | nval = futex_atomic_cmpxchg_inatomic(uaddr, uval, mval); | |
1899 | ||
c87e2837 IM |
1900 | if (nval == -EFAULT) |
1901 | return -1; | |
1902 | ||
1903 | if (nval != uval) | |
8f17d3a5 | 1904 | goto retry; |
0771dfef | 1905 | |
e3f2ddea IM |
1906 | /* |
1907 | * Wake robust non-PI futexes here. The wakeup of | |
1908 | * PI futexes happens in exit_pi_state(): | |
1909 | */ | |
36cf3b5c | 1910 | if (!pi && (uval & FUTEX_WAITERS)) |
cd689985 TG |
1911 | futex_wake(uaddr, &curr->mm->mmap_sem, 1, |
1912 | FUTEX_BITSET_MATCH_ANY); | |
0771dfef IM |
1913 | } |
1914 | return 0; | |
1915 | } | |
1916 | ||
e3f2ddea IM |
1917 | /* |
1918 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: | |
1919 | */ | |
1920 | static inline int fetch_robust_entry(struct robust_list __user **entry, | |
ba46df98 AV |
1921 | struct robust_list __user * __user *head, |
1922 | int *pi) | |
e3f2ddea IM |
1923 | { |
1924 | unsigned long uentry; | |
1925 | ||
ba46df98 | 1926 | if (get_user(uentry, (unsigned long __user *)head)) |
e3f2ddea IM |
1927 | return -EFAULT; |
1928 | ||
ba46df98 | 1929 | *entry = (void __user *)(uentry & ~1UL); |
e3f2ddea IM |
1930 | *pi = uentry & 1; |
1931 | ||
1932 | return 0; | |
1933 | } | |
1934 | ||
0771dfef IM |
1935 | /* |
1936 | * Walk curr->robust_list (very carefully, it's a userspace list!) | |
1937 | * and mark any locks found there dead, and notify any waiters. | |
1938 | * | |
1939 | * We silently return on any sign of list-walking problem. | |
1940 | */ | |
1941 | void exit_robust_list(struct task_struct *curr) | |
1942 | { | |
1943 | struct robust_list_head __user *head = curr->robust_list; | |
9f96cb1e MS |
1944 | struct robust_list __user *entry, *next_entry, *pending; |
1945 | unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip; | |
0771dfef | 1946 | unsigned long futex_offset; |
9f96cb1e | 1947 | int rc; |
0771dfef | 1948 | |
a0c1e907 TG |
1949 | if (!futex_cmpxchg_enabled) |
1950 | return; | |
1951 | ||
0771dfef IM |
1952 | /* |
1953 | * Fetch the list head (which was registered earlier, via | |
1954 | * sys_set_robust_list()): | |
1955 | */ | |
e3f2ddea | 1956 | if (fetch_robust_entry(&entry, &head->list.next, &pi)) |
0771dfef IM |
1957 | return; |
1958 | /* | |
1959 | * Fetch the relative futex offset: | |
1960 | */ | |
1961 | if (get_user(futex_offset, &head->futex_offset)) | |
1962 | return; | |
1963 | /* | |
1964 | * Fetch any possibly pending lock-add first, and handle it | |
1965 | * if it exists: | |
1966 | */ | |
e3f2ddea | 1967 | if (fetch_robust_entry(&pending, &head->list_op_pending, &pip)) |
0771dfef | 1968 | return; |
e3f2ddea | 1969 | |
9f96cb1e | 1970 | next_entry = NULL; /* avoid warning with gcc */ |
0771dfef | 1971 | while (entry != &head->list) { |
9f96cb1e MS |
1972 | /* |
1973 | * Fetch the next entry in the list before calling | |
1974 | * handle_futex_death: | |
1975 | */ | |
1976 | rc = fetch_robust_entry(&next_entry, &entry->next, &next_pi); | |
0771dfef IM |
1977 | /* |
1978 | * A pending lock might already be on the list, so | |
c87e2837 | 1979 | * don't process it twice: |
0771dfef IM |
1980 | */ |
1981 | if (entry != pending) | |
ba46df98 | 1982 | if (handle_futex_death((void __user *)entry + futex_offset, |
e3f2ddea | 1983 | curr, pi)) |
0771dfef | 1984 | return; |
9f96cb1e | 1985 | if (rc) |
0771dfef | 1986 | return; |
9f96cb1e MS |
1987 | entry = next_entry; |
1988 | pi = next_pi; | |
0771dfef IM |
1989 | /* |
1990 | * Avoid excessively long or circular lists: | |
1991 | */ | |
1992 | if (!--limit) | |
1993 | break; | |
1994 | ||
1995 | cond_resched(); | |
1996 | } | |
9f96cb1e MS |
1997 | |
1998 | if (pending) | |
1999 | handle_futex_death((void __user *)pending + futex_offset, | |
2000 | curr, pip); | |
0771dfef IM |
2001 | } |
2002 | ||
c19384b5 | 2003 | long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, |
e2970f2f | 2004 | u32 __user *uaddr2, u32 val2, u32 val3) |
1da177e4 | 2005 | { |
a0c1e907 | 2006 | int ret = -ENOSYS; |
34f01cc1 ED |
2007 | int cmd = op & FUTEX_CMD_MASK; |
2008 | struct rw_semaphore *fshared = NULL; | |
2009 | ||
2010 | if (!(op & FUTEX_PRIVATE_FLAG)) | |
2011 | fshared = ¤t->mm->mmap_sem; | |
1da177e4 | 2012 | |
34f01cc1 | 2013 | switch (cmd) { |
1da177e4 | 2014 | case FUTEX_WAIT: |
cd689985 TG |
2015 | val3 = FUTEX_BITSET_MATCH_ANY; |
2016 | case FUTEX_WAIT_BITSET: | |
2017 | ret = futex_wait(uaddr, fshared, val, timeout, val3); | |
1da177e4 LT |
2018 | break; |
2019 | case FUTEX_WAKE: | |
cd689985 TG |
2020 | val3 = FUTEX_BITSET_MATCH_ANY; |
2021 | case FUTEX_WAKE_BITSET: | |
2022 | ret = futex_wake(uaddr, fshared, val, val3); | |
1da177e4 | 2023 | break; |
1da177e4 | 2024 | case FUTEX_REQUEUE: |
34f01cc1 | 2025 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL); |
1da177e4 LT |
2026 | break; |
2027 | case FUTEX_CMP_REQUEUE: | |
34f01cc1 | 2028 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3); |
1da177e4 | 2029 | break; |
4732efbe | 2030 | case FUTEX_WAKE_OP: |
34f01cc1 | 2031 | ret = futex_wake_op(uaddr, fshared, uaddr2, val, val2, val3); |
4732efbe | 2032 | break; |
c87e2837 | 2033 | case FUTEX_LOCK_PI: |
a0c1e907 TG |
2034 | if (futex_cmpxchg_enabled) |
2035 | ret = futex_lock_pi(uaddr, fshared, val, timeout, 0); | |
c87e2837 IM |
2036 | break; |
2037 | case FUTEX_UNLOCK_PI: | |
a0c1e907 TG |
2038 | if (futex_cmpxchg_enabled) |
2039 | ret = futex_unlock_pi(uaddr, fshared); | |
c87e2837 IM |
2040 | break; |
2041 | case FUTEX_TRYLOCK_PI: | |
a0c1e907 TG |
2042 | if (futex_cmpxchg_enabled) |
2043 | ret = futex_lock_pi(uaddr, fshared, 0, timeout, 1); | |
c87e2837 | 2044 | break; |
1da177e4 LT |
2045 | default: |
2046 | ret = -ENOSYS; | |
2047 | } | |
2048 | return ret; | |
2049 | } | |
2050 | ||
2051 | ||
e2970f2f | 2052 | asmlinkage long sys_futex(u32 __user *uaddr, int op, u32 val, |
1da177e4 | 2053 | struct timespec __user *utime, u32 __user *uaddr2, |
e2970f2f | 2054 | u32 val3) |
1da177e4 | 2055 | { |
c19384b5 PP |
2056 | struct timespec ts; |
2057 | ktime_t t, *tp = NULL; | |
e2970f2f | 2058 | u32 val2 = 0; |
34f01cc1 | 2059 | int cmd = op & FUTEX_CMD_MASK; |
1da177e4 | 2060 | |
cd689985 TG |
2061 | if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
2062 | cmd == FUTEX_WAIT_BITSET)) { | |
c19384b5 | 2063 | if (copy_from_user(&ts, utime, sizeof(ts)) != 0) |
1da177e4 | 2064 | return -EFAULT; |
c19384b5 | 2065 | if (!timespec_valid(&ts)) |
9741ef96 | 2066 | return -EINVAL; |
c19384b5 PP |
2067 | |
2068 | t = timespec_to_ktime(ts); | |
34f01cc1 | 2069 | if (cmd == FUTEX_WAIT) |
5a7780e7 | 2070 | t = ktime_add_safe(ktime_get(), t); |
c19384b5 | 2071 | tp = &t; |
1da177e4 LT |
2072 | } |
2073 | /* | |
34f01cc1 | 2074 | * requeue parameter in 'utime' if cmd == FUTEX_REQUEUE. |
f54f0986 | 2075 | * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP. |
1da177e4 | 2076 | */ |
f54f0986 AS |
2077 | if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
2078 | cmd == FUTEX_WAKE_OP) | |
e2970f2f | 2079 | val2 = (u32) (unsigned long) utime; |
1da177e4 | 2080 | |
c19384b5 | 2081 | return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
1da177e4 LT |
2082 | } |
2083 | ||
f6d107fb | 2084 | static int __init futex_init(void) |
1da177e4 | 2085 | { |
a0c1e907 | 2086 | u32 curval; |
3e4ab747 | 2087 | int i; |
95362fa9 | 2088 | |
a0c1e907 TG |
2089 | /* |
2090 | * This will fail and we want it. Some arch implementations do | |
2091 | * runtime detection of the futex_atomic_cmpxchg_inatomic() | |
2092 | * functionality. We want to know that before we call in any | |
2093 | * of the complex code paths. Also we want to prevent | |
2094 | * registration of robust lists in that case. NULL is | |
2095 | * guaranteed to fault and we get -EFAULT on functional | |
2096 | * implementation, the non functional ones will return | |
2097 | * -ENOSYS. | |
2098 | */ | |
2099 | curval = cmpxchg_futex_value_locked(NULL, 0, 0); | |
2100 | if (curval == -EFAULT) | |
2101 | futex_cmpxchg_enabled = 1; | |
2102 | ||
3e4ab747 TG |
2103 | for (i = 0; i < ARRAY_SIZE(futex_queues); i++) { |
2104 | plist_head_init(&futex_queues[i].chain, &futex_queues[i].lock); | |
2105 | spin_lock_init(&futex_queues[i].lock); | |
2106 | } | |
2107 | ||
1da177e4 LT |
2108 | return 0; |
2109 | } | |
f6d107fb | 2110 | __initcall(futex_init); |