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 | ||
e2970f2f | 107 | /* For fd, sigio sent using these: */ |
1da177e4 LT |
108 | int fd; |
109 | struct file *filp; | |
c87e2837 IM |
110 | |
111 | /* Optional priority inheritance state: */ | |
112 | struct futex_pi_state *pi_state; | |
113 | struct task_struct *task; | |
cd689985 TG |
114 | |
115 | /* Bitset for the optional bitmasked wakeup */ | |
116 | u32 bitset; | |
1da177e4 LT |
117 | }; |
118 | ||
119 | /* | |
120 | * Split the global futex_lock into every hash list lock. | |
121 | */ | |
122 | struct futex_hash_bucket { | |
ec92d082 PP |
123 | spinlock_t lock; |
124 | struct plist_head chain; | |
1da177e4 LT |
125 | }; |
126 | ||
127 | static struct futex_hash_bucket futex_queues[1<<FUTEX_HASHBITS]; | |
128 | ||
129 | /* Futex-fs vfsmount entry: */ | |
130 | static struct vfsmount *futex_mnt; | |
131 | ||
36cf3b5c TG |
132 | /* |
133 | * Take mm->mmap_sem, when futex is shared | |
134 | */ | |
135 | static inline void futex_lock_mm(struct rw_semaphore *fshared) | |
136 | { | |
137 | if (fshared) | |
138 | down_read(fshared); | |
139 | } | |
140 | ||
141 | /* | |
142 | * Release mm->mmap_sem, when the futex is shared | |
143 | */ | |
144 | static inline void futex_unlock_mm(struct rw_semaphore *fshared) | |
145 | { | |
146 | if (fshared) | |
147 | up_read(fshared); | |
148 | } | |
149 | ||
1da177e4 LT |
150 | /* |
151 | * We hash on the keys returned from get_futex_key (see below). | |
152 | */ | |
153 | static struct futex_hash_bucket *hash_futex(union futex_key *key) | |
154 | { | |
155 | u32 hash = jhash2((u32*)&key->both.word, | |
156 | (sizeof(key->both.word)+sizeof(key->both.ptr))/4, | |
157 | key->both.offset); | |
158 | return &futex_queues[hash & ((1 << FUTEX_HASHBITS)-1)]; | |
159 | } | |
160 | ||
161 | /* | |
162 | * Return 1 if two futex_keys are equal, 0 otherwise. | |
163 | */ | |
164 | static inline int match_futex(union futex_key *key1, union futex_key *key2) | |
165 | { | |
166 | return (key1->both.word == key2->both.word | |
167 | && key1->both.ptr == key2->both.ptr | |
168 | && key1->both.offset == key2->both.offset); | |
169 | } | |
170 | ||
34f01cc1 ED |
171 | /** |
172 | * get_futex_key - Get parameters which are the keys for a futex. | |
173 | * @uaddr: virtual address of the futex | |
174 | * @shared: NULL for a PROCESS_PRIVATE futex, | |
175 | * ¤t->mm->mmap_sem for a PROCESS_SHARED futex | |
176 | * @key: address where result is stored. | |
177 | * | |
178 | * Returns a negative error code or 0 | |
179 | * The key words are stored in *key on success. | |
1da177e4 | 180 | * |
f3a43f3f | 181 | * For shared mappings, it's (page->index, vma->vm_file->f_path.dentry->d_inode, |
1da177e4 LT |
182 | * offset_within_page). For private mappings, it's (uaddr, current->mm). |
183 | * We can usually work out the index without swapping in the page. | |
184 | * | |
34f01cc1 ED |
185 | * fshared is NULL for PROCESS_PRIVATE futexes |
186 | * For other futexes, it points to ¤t->mm->mmap_sem and | |
187 | * caller must have taken the reader lock. but NOT any spinlocks. | |
1da177e4 | 188 | */ |
fad23fc7 AB |
189 | static int get_futex_key(u32 __user *uaddr, struct rw_semaphore *fshared, |
190 | union futex_key *key) | |
1da177e4 | 191 | { |
e2970f2f | 192 | unsigned long address = (unsigned long)uaddr; |
1da177e4 LT |
193 | struct mm_struct *mm = current->mm; |
194 | struct vm_area_struct *vma; | |
195 | struct page *page; | |
196 | int err; | |
197 | ||
198 | /* | |
199 | * The futex address must be "naturally" aligned. | |
200 | */ | |
e2970f2f | 201 | key->both.offset = address % PAGE_SIZE; |
34f01cc1 | 202 | if (unlikely((address % sizeof(u32)) != 0)) |
1da177e4 | 203 | return -EINVAL; |
e2970f2f | 204 | address -= key->both.offset; |
1da177e4 | 205 | |
34f01cc1 ED |
206 | /* |
207 | * PROCESS_PRIVATE futexes are fast. | |
208 | * As the mm cannot disappear under us and the 'key' only needs | |
209 | * virtual address, we dont even have to find the underlying vma. | |
210 | * Note : We do have to check 'uaddr' is a valid user address, | |
211 | * but access_ok() should be faster than find_vma() | |
212 | */ | |
213 | if (!fshared) { | |
214 | if (unlikely(!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))) | |
215 | return -EFAULT; | |
216 | key->private.mm = mm; | |
217 | key->private.address = address; | |
218 | return 0; | |
219 | } | |
1da177e4 LT |
220 | /* |
221 | * The futex is hashed differently depending on whether | |
222 | * it's in a shared or private mapping. So check vma first. | |
223 | */ | |
e2970f2f | 224 | vma = find_extend_vma(mm, address); |
1da177e4 LT |
225 | if (unlikely(!vma)) |
226 | return -EFAULT; | |
227 | ||
228 | /* | |
229 | * Permissions. | |
230 | */ | |
231 | if (unlikely((vma->vm_flags & (VM_IO|VM_READ)) != VM_READ)) | |
232 | return (vma->vm_flags & VM_IO) ? -EPERM : -EACCES; | |
233 | ||
234 | /* | |
235 | * Private mappings are handled in a simple way. | |
236 | * | |
237 | * NOTE: When userspace waits on a MAP_SHARED mapping, even if | |
238 | * it's a read-only handle, it's expected that futexes attach to | |
239 | * the object not the particular process. Therefore we use | |
240 | * VM_MAYSHARE here, not VM_SHARED which is restricted to shared | |
241 | * mappings of _writable_ handles. | |
242 | */ | |
243 | if (likely(!(vma->vm_flags & VM_MAYSHARE))) { | |
34f01cc1 | 244 | key->both.offset |= FUT_OFF_MMSHARED; /* reference taken on mm */ |
1da177e4 | 245 | key->private.mm = mm; |
e2970f2f | 246 | key->private.address = address; |
1da177e4 LT |
247 | return 0; |
248 | } | |
249 | ||
250 | /* | |
251 | * Linear file mappings are also simple. | |
252 | */ | |
f3a43f3f | 253 | key->shared.inode = vma->vm_file->f_path.dentry->d_inode; |
34f01cc1 | 254 | key->both.offset |= FUT_OFF_INODE; /* inode-based key. */ |
1da177e4 | 255 | if (likely(!(vma->vm_flags & VM_NONLINEAR))) { |
e2970f2f | 256 | key->shared.pgoff = (((address - vma->vm_start) >> PAGE_SHIFT) |
1da177e4 LT |
257 | + vma->vm_pgoff); |
258 | return 0; | |
259 | } | |
260 | ||
261 | /* | |
262 | * We could walk the page table to read the non-linear | |
263 | * pte, and get the page index without fetching the page | |
264 | * from swap. But that's a lot of code to duplicate here | |
265 | * for a rare case, so we simply fetch the page. | |
266 | */ | |
e2970f2f | 267 | err = get_user_pages(current, mm, address, 1, 0, 0, &page, NULL); |
1da177e4 LT |
268 | if (err >= 0) { |
269 | key->shared.pgoff = | |
270 | page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
271 | put_page(page); | |
272 | return 0; | |
273 | } | |
274 | return err; | |
275 | } | |
276 | ||
277 | /* | |
278 | * Take a reference to the resource addressed by a key. | |
279 | * Can be called while holding spinlocks. | |
280 | * | |
1da177e4 | 281 | */ |
fad23fc7 | 282 | static void get_futex_key_refs(union futex_key *key) |
1da177e4 | 283 | { |
9dce07f1 | 284 | if (key->both.ptr == NULL) |
34f01cc1 ED |
285 | return; |
286 | switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { | |
287 | case FUT_OFF_INODE: | |
1da177e4 | 288 | atomic_inc(&key->shared.inode->i_count); |
34f01cc1 ED |
289 | break; |
290 | case FUT_OFF_MMSHARED: | |
1da177e4 | 291 | atomic_inc(&key->private.mm->mm_count); |
34f01cc1 | 292 | break; |
1da177e4 LT |
293 | } |
294 | } | |
295 | ||
296 | /* | |
297 | * Drop a reference to the resource addressed by a key. | |
298 | * The hash bucket spinlock must not be held. | |
299 | */ | |
fad23fc7 | 300 | static void drop_futex_key_refs(union futex_key *key) |
1da177e4 | 301 | { |
c80544dc | 302 | if (!key->both.ptr) |
34f01cc1 ED |
303 | return; |
304 | switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { | |
305 | case FUT_OFF_INODE: | |
1da177e4 | 306 | iput(key->shared.inode); |
34f01cc1 ED |
307 | break; |
308 | case FUT_OFF_MMSHARED: | |
1da177e4 | 309 | mmdrop(key->private.mm); |
34f01cc1 | 310 | break; |
1da177e4 LT |
311 | } |
312 | } | |
313 | ||
36cf3b5c TG |
314 | static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval) |
315 | { | |
316 | u32 curval; | |
317 | ||
318 | pagefault_disable(); | |
319 | curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval); | |
320 | pagefault_enable(); | |
321 | ||
322 | return curval; | |
323 | } | |
324 | ||
325 | static int get_futex_value_locked(u32 *dest, u32 __user *from) | |
1da177e4 LT |
326 | { |
327 | int ret; | |
328 | ||
a866374a | 329 | pagefault_disable(); |
e2970f2f | 330 | ret = __copy_from_user_inatomic(dest, from, sizeof(u32)); |
a866374a | 331 | pagefault_enable(); |
1da177e4 LT |
332 | |
333 | return ret ? -EFAULT : 0; | |
334 | } | |
335 | ||
c87e2837 | 336 | /* |
34f01cc1 ED |
337 | * Fault handling. |
338 | * if fshared is non NULL, current->mm->mmap_sem is already held | |
c87e2837 | 339 | */ |
34f01cc1 ED |
340 | static int futex_handle_fault(unsigned long address, |
341 | struct rw_semaphore *fshared, int attempt) | |
c87e2837 IM |
342 | { |
343 | struct vm_area_struct * vma; | |
344 | struct mm_struct *mm = current->mm; | |
34f01cc1 | 345 | int ret = -EFAULT; |
c87e2837 | 346 | |
34f01cc1 ED |
347 | if (attempt > 2) |
348 | return ret; | |
c87e2837 | 349 | |
34f01cc1 ED |
350 | if (!fshared) |
351 | down_read(&mm->mmap_sem); | |
352 | vma = find_vma(mm, address); | |
353 | if (vma && address >= vma->vm_start && | |
354 | (vma->vm_flags & VM_WRITE)) { | |
83c54070 NP |
355 | int fault; |
356 | fault = handle_mm_fault(mm, vma, address, 1); | |
357 | if (unlikely((fault & VM_FAULT_ERROR))) { | |
358 | #if 0 | |
359 | /* XXX: let's do this when we verify it is OK */ | |
360 | if (ret & VM_FAULT_OOM) | |
361 | ret = -ENOMEM; | |
362 | #endif | |
363 | } else { | |
34f01cc1 | 364 | ret = 0; |
83c54070 NP |
365 | if (fault & VM_FAULT_MAJOR) |
366 | current->maj_flt++; | |
367 | else | |
368 | current->min_flt++; | |
34f01cc1 | 369 | } |
c87e2837 | 370 | } |
34f01cc1 ED |
371 | if (!fshared) |
372 | up_read(&mm->mmap_sem); | |
373 | return ret; | |
c87e2837 IM |
374 | } |
375 | ||
376 | /* | |
377 | * PI code: | |
378 | */ | |
379 | static int refill_pi_state_cache(void) | |
380 | { | |
381 | struct futex_pi_state *pi_state; | |
382 | ||
383 | if (likely(current->pi_state_cache)) | |
384 | return 0; | |
385 | ||
4668edc3 | 386 | pi_state = kzalloc(sizeof(*pi_state), GFP_KERNEL); |
c87e2837 IM |
387 | |
388 | if (!pi_state) | |
389 | return -ENOMEM; | |
390 | ||
c87e2837 IM |
391 | INIT_LIST_HEAD(&pi_state->list); |
392 | /* pi_mutex gets initialized later */ | |
393 | pi_state->owner = NULL; | |
394 | atomic_set(&pi_state->refcount, 1); | |
395 | ||
396 | current->pi_state_cache = pi_state; | |
397 | ||
398 | return 0; | |
399 | } | |
400 | ||
401 | static struct futex_pi_state * alloc_pi_state(void) | |
402 | { | |
403 | struct futex_pi_state *pi_state = current->pi_state_cache; | |
404 | ||
405 | WARN_ON(!pi_state); | |
406 | current->pi_state_cache = NULL; | |
407 | ||
408 | return pi_state; | |
409 | } | |
410 | ||
411 | static void free_pi_state(struct futex_pi_state *pi_state) | |
412 | { | |
413 | if (!atomic_dec_and_test(&pi_state->refcount)) | |
414 | return; | |
415 | ||
416 | /* | |
417 | * If pi_state->owner is NULL, the owner is most probably dying | |
418 | * and has cleaned up the pi_state already | |
419 | */ | |
420 | if (pi_state->owner) { | |
421 | spin_lock_irq(&pi_state->owner->pi_lock); | |
422 | list_del_init(&pi_state->list); | |
423 | spin_unlock_irq(&pi_state->owner->pi_lock); | |
424 | ||
425 | rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner); | |
426 | } | |
427 | ||
428 | if (current->pi_state_cache) | |
429 | kfree(pi_state); | |
430 | else { | |
431 | /* | |
432 | * pi_state->list is already empty. | |
433 | * clear pi_state->owner. | |
434 | * refcount is at 0 - put it back to 1. | |
435 | */ | |
436 | pi_state->owner = NULL; | |
437 | atomic_set(&pi_state->refcount, 1); | |
438 | current->pi_state_cache = pi_state; | |
439 | } | |
440 | } | |
441 | ||
442 | /* | |
443 | * Look up the task based on what TID userspace gave us. | |
444 | * We dont trust it. | |
445 | */ | |
446 | static struct task_struct * futex_find_get_task(pid_t pid) | |
447 | { | |
448 | struct task_struct *p; | |
449 | ||
d359b549 | 450 | rcu_read_lock(); |
228ebcbe | 451 | p = find_task_by_vpid(pid); |
a06381fe TG |
452 | if (!p || ((current->euid != p->euid) && (current->euid != p->uid))) |
453 | p = ERR_PTR(-ESRCH); | |
454 | else | |
455 | get_task_struct(p); | |
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 | if (q->filp) |
614 | send_sigio(&q->filp->f_owner, q->fd, POLL_IN); | |
615 | /* | |
616 | * The lock in wake_up_all() is a crucial memory barrier after the | |
ec92d082 | 617 | * plist_del() and also before assigning to q->lock_ptr. |
1da177e4 LT |
618 | */ |
619 | wake_up_all(&q->waiters); | |
620 | /* | |
621 | * The waiting task can free the futex_q as soon as this is written, | |
622 | * without taking any locks. This must come last. | |
8e31108b AM |
623 | * |
624 | * A memory barrier is required here to prevent the following store | |
625 | * to lock_ptr from getting ahead of the wakeup. Clearing the lock | |
626 | * at the end of wake_up_all() does not prevent this store from | |
627 | * moving. | |
1da177e4 | 628 | */ |
ccdea2f8 | 629 | smp_wmb(); |
1da177e4 LT |
630 | q->lock_ptr = NULL; |
631 | } | |
632 | ||
c87e2837 IM |
633 | static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this) |
634 | { | |
635 | struct task_struct *new_owner; | |
636 | struct futex_pi_state *pi_state = this->pi_state; | |
637 | u32 curval, newval; | |
638 | ||
639 | if (!pi_state) | |
640 | return -EINVAL; | |
641 | ||
21778867 | 642 | spin_lock(&pi_state->pi_mutex.wait_lock); |
c87e2837 IM |
643 | new_owner = rt_mutex_next_owner(&pi_state->pi_mutex); |
644 | ||
645 | /* | |
646 | * This happens when we have stolen the lock and the original | |
647 | * pending owner did not enqueue itself back on the rt_mutex. | |
648 | * Thats not a tragedy. We know that way, that a lock waiter | |
649 | * is on the fly. We make the futex_q waiter the pending owner. | |
650 | */ | |
651 | if (!new_owner) | |
652 | new_owner = this->task; | |
653 | ||
654 | /* | |
655 | * We pass it to the next owner. (The WAITERS bit is always | |
656 | * kept enabled while there is PI state around. We must also | |
657 | * preserve the owner died bit.) | |
658 | */ | |
e3f2ddea | 659 | if (!(uval & FUTEX_OWNER_DIED)) { |
778e9a9c AK |
660 | int ret = 0; |
661 | ||
b488893a | 662 | newval = FUTEX_WAITERS | task_pid_vnr(new_owner); |
e3f2ddea | 663 | |
36cf3b5c | 664 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
778e9a9c | 665 | |
e3f2ddea | 666 | if (curval == -EFAULT) |
778e9a9c | 667 | ret = -EFAULT; |
cde898fa | 668 | else if (curval != uval) |
778e9a9c AK |
669 | ret = -EINVAL; |
670 | if (ret) { | |
671 | spin_unlock(&pi_state->pi_mutex.wait_lock); | |
672 | return ret; | |
673 | } | |
e3f2ddea | 674 | } |
c87e2837 | 675 | |
627371d7 IM |
676 | spin_lock_irq(&pi_state->owner->pi_lock); |
677 | WARN_ON(list_empty(&pi_state->list)); | |
678 | list_del_init(&pi_state->list); | |
679 | spin_unlock_irq(&pi_state->owner->pi_lock); | |
680 | ||
681 | spin_lock_irq(&new_owner->pi_lock); | |
682 | WARN_ON(!list_empty(&pi_state->list)); | |
c87e2837 IM |
683 | list_add(&pi_state->list, &new_owner->pi_state_list); |
684 | pi_state->owner = new_owner; | |
627371d7 IM |
685 | spin_unlock_irq(&new_owner->pi_lock); |
686 | ||
21778867 | 687 | spin_unlock(&pi_state->pi_mutex.wait_lock); |
c87e2837 IM |
688 | rt_mutex_unlock(&pi_state->pi_mutex); |
689 | ||
690 | return 0; | |
691 | } | |
692 | ||
693 | static int unlock_futex_pi(u32 __user *uaddr, u32 uval) | |
694 | { | |
695 | u32 oldval; | |
696 | ||
697 | /* | |
698 | * There is no waiter, so we unlock the futex. The owner died | |
699 | * bit has not to be preserved here. We are the owner: | |
700 | */ | |
36cf3b5c | 701 | oldval = cmpxchg_futex_value_locked(uaddr, uval, 0); |
c87e2837 IM |
702 | |
703 | if (oldval == -EFAULT) | |
704 | return oldval; | |
705 | if (oldval != uval) | |
706 | return -EAGAIN; | |
707 | ||
708 | return 0; | |
709 | } | |
710 | ||
8b8f319f IM |
711 | /* |
712 | * Express the locking dependencies for lockdep: | |
713 | */ | |
714 | static inline void | |
715 | double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) | |
716 | { | |
717 | if (hb1 <= hb2) { | |
718 | spin_lock(&hb1->lock); | |
719 | if (hb1 < hb2) | |
720 | spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); | |
721 | } else { /* hb1 > hb2 */ | |
722 | spin_lock(&hb2->lock); | |
723 | spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); | |
724 | } | |
725 | } | |
726 | ||
1da177e4 LT |
727 | /* |
728 | * Wake up all waiters hashed on the physical page that is mapped | |
729 | * to this virtual address: | |
730 | */ | |
34f01cc1 | 731 | static int futex_wake(u32 __user *uaddr, struct rw_semaphore *fshared, |
cd689985 | 732 | int nr_wake, u32 bitset) |
1da177e4 | 733 | { |
e2970f2f | 734 | struct futex_hash_bucket *hb; |
1da177e4 | 735 | struct futex_q *this, *next; |
ec92d082 | 736 | struct plist_head *head; |
e2970f2f | 737 | union futex_key key; |
1da177e4 LT |
738 | int ret; |
739 | ||
cd689985 TG |
740 | if (!bitset) |
741 | return -EINVAL; | |
742 | ||
36cf3b5c | 743 | futex_lock_mm(fshared); |
1da177e4 | 744 | |
34f01cc1 | 745 | ret = get_futex_key(uaddr, fshared, &key); |
1da177e4 LT |
746 | if (unlikely(ret != 0)) |
747 | goto out; | |
748 | ||
e2970f2f IM |
749 | hb = hash_futex(&key); |
750 | spin_lock(&hb->lock); | |
751 | head = &hb->chain; | |
1da177e4 | 752 | |
ec92d082 | 753 | plist_for_each_entry_safe(this, next, head, list) { |
1da177e4 | 754 | if (match_futex (&this->key, &key)) { |
ed6f7b10 IM |
755 | if (this->pi_state) { |
756 | ret = -EINVAL; | |
757 | break; | |
758 | } | |
cd689985 TG |
759 | |
760 | /* Check if one of the bits is set in both bitsets */ | |
761 | if (!(this->bitset & bitset)) | |
762 | continue; | |
763 | ||
1da177e4 LT |
764 | wake_futex(this); |
765 | if (++ret >= nr_wake) | |
766 | break; | |
767 | } | |
768 | } | |
769 | ||
e2970f2f | 770 | spin_unlock(&hb->lock); |
1da177e4 | 771 | out: |
36cf3b5c | 772 | futex_unlock_mm(fshared); |
1da177e4 LT |
773 | return ret; |
774 | } | |
775 | ||
4732efbe JJ |
776 | /* |
777 | * Wake up all waiters hashed on the physical page that is mapped | |
778 | * to this virtual address: | |
779 | */ | |
e2970f2f | 780 | static int |
34f01cc1 ED |
781 | futex_wake_op(u32 __user *uaddr1, struct rw_semaphore *fshared, |
782 | u32 __user *uaddr2, | |
e2970f2f | 783 | int nr_wake, int nr_wake2, int op) |
4732efbe JJ |
784 | { |
785 | union futex_key key1, key2; | |
e2970f2f | 786 | struct futex_hash_bucket *hb1, *hb2; |
ec92d082 | 787 | struct plist_head *head; |
4732efbe JJ |
788 | struct futex_q *this, *next; |
789 | int ret, op_ret, attempt = 0; | |
790 | ||
791 | retryfull: | |
36cf3b5c | 792 | futex_lock_mm(fshared); |
4732efbe | 793 | |
34f01cc1 | 794 | ret = get_futex_key(uaddr1, fshared, &key1); |
4732efbe JJ |
795 | if (unlikely(ret != 0)) |
796 | goto out; | |
34f01cc1 | 797 | ret = get_futex_key(uaddr2, fshared, &key2); |
4732efbe JJ |
798 | if (unlikely(ret != 0)) |
799 | goto out; | |
800 | ||
e2970f2f IM |
801 | hb1 = hash_futex(&key1); |
802 | hb2 = hash_futex(&key2); | |
4732efbe JJ |
803 | |
804 | retry: | |
8b8f319f | 805 | double_lock_hb(hb1, hb2); |
4732efbe | 806 | |
e2970f2f | 807 | op_ret = futex_atomic_op_inuser(op, uaddr2); |
4732efbe | 808 | if (unlikely(op_ret < 0)) { |
e2970f2f | 809 | u32 dummy; |
4732efbe | 810 | |
e2970f2f IM |
811 | spin_unlock(&hb1->lock); |
812 | if (hb1 != hb2) | |
813 | spin_unlock(&hb2->lock); | |
4732efbe | 814 | |
7ee1dd3f | 815 | #ifndef CONFIG_MMU |
e2970f2f IM |
816 | /* |
817 | * we don't get EFAULT from MMU faults if we don't have an MMU, | |
818 | * but we might get them from range checking | |
819 | */ | |
7ee1dd3f DH |
820 | ret = op_ret; |
821 | goto out; | |
822 | #endif | |
823 | ||
796f8d9b DG |
824 | if (unlikely(op_ret != -EFAULT)) { |
825 | ret = op_ret; | |
826 | goto out; | |
827 | } | |
828 | ||
e2970f2f IM |
829 | /* |
830 | * futex_atomic_op_inuser needs to both read and write | |
4732efbe JJ |
831 | * *(int __user *)uaddr2, but we can't modify it |
832 | * non-atomically. Therefore, if get_user below is not | |
833 | * enough, we need to handle the fault ourselves, while | |
e2970f2f IM |
834 | * still holding the mmap_sem. |
835 | */ | |
4732efbe | 836 | if (attempt++) { |
34f01cc1 | 837 | ret = futex_handle_fault((unsigned long)uaddr2, |
36cf3b5c | 838 | fshared, attempt); |
34f01cc1 | 839 | if (ret) |
4732efbe | 840 | goto out; |
4732efbe JJ |
841 | goto retry; |
842 | } | |
843 | ||
e2970f2f IM |
844 | /* |
845 | * If we would have faulted, release mmap_sem, | |
846 | * fault it in and start all over again. | |
847 | */ | |
36cf3b5c | 848 | futex_unlock_mm(fshared); |
4732efbe | 849 | |
e2970f2f | 850 | ret = get_user(dummy, uaddr2); |
4732efbe JJ |
851 | if (ret) |
852 | return ret; | |
853 | ||
854 | goto retryfull; | |
855 | } | |
856 | ||
e2970f2f | 857 | head = &hb1->chain; |
4732efbe | 858 | |
ec92d082 | 859 | plist_for_each_entry_safe(this, next, head, list) { |
4732efbe JJ |
860 | if (match_futex (&this->key, &key1)) { |
861 | wake_futex(this); | |
862 | if (++ret >= nr_wake) | |
863 | break; | |
864 | } | |
865 | } | |
866 | ||
867 | if (op_ret > 0) { | |
e2970f2f | 868 | head = &hb2->chain; |
4732efbe JJ |
869 | |
870 | op_ret = 0; | |
ec92d082 | 871 | plist_for_each_entry_safe(this, next, head, list) { |
4732efbe JJ |
872 | if (match_futex (&this->key, &key2)) { |
873 | wake_futex(this); | |
874 | if (++op_ret >= nr_wake2) | |
875 | break; | |
876 | } | |
877 | } | |
878 | ret += op_ret; | |
879 | } | |
880 | ||
e2970f2f IM |
881 | spin_unlock(&hb1->lock); |
882 | if (hb1 != hb2) | |
883 | spin_unlock(&hb2->lock); | |
4732efbe | 884 | out: |
36cf3b5c TG |
885 | futex_unlock_mm(fshared); |
886 | ||
4732efbe JJ |
887 | return ret; |
888 | } | |
889 | ||
1da177e4 LT |
890 | /* |
891 | * Requeue all waiters hashed on one physical page to another | |
892 | * physical page. | |
893 | */ | |
34f01cc1 ED |
894 | static int futex_requeue(u32 __user *uaddr1, struct rw_semaphore *fshared, |
895 | u32 __user *uaddr2, | |
e2970f2f | 896 | int nr_wake, int nr_requeue, u32 *cmpval) |
1da177e4 LT |
897 | { |
898 | union futex_key key1, key2; | |
e2970f2f | 899 | struct futex_hash_bucket *hb1, *hb2; |
ec92d082 | 900 | struct plist_head *head1; |
1da177e4 LT |
901 | struct futex_q *this, *next; |
902 | int ret, drop_count = 0; | |
903 | ||
904 | retry: | |
36cf3b5c | 905 | futex_lock_mm(fshared); |
1da177e4 | 906 | |
34f01cc1 | 907 | ret = get_futex_key(uaddr1, fshared, &key1); |
1da177e4 LT |
908 | if (unlikely(ret != 0)) |
909 | goto out; | |
34f01cc1 | 910 | ret = get_futex_key(uaddr2, fshared, &key2); |
1da177e4 LT |
911 | if (unlikely(ret != 0)) |
912 | goto out; | |
913 | ||
e2970f2f IM |
914 | hb1 = hash_futex(&key1); |
915 | hb2 = hash_futex(&key2); | |
1da177e4 | 916 | |
8b8f319f | 917 | double_lock_hb(hb1, hb2); |
1da177e4 | 918 | |
e2970f2f IM |
919 | if (likely(cmpval != NULL)) { |
920 | u32 curval; | |
1da177e4 | 921 | |
e2970f2f | 922 | ret = get_futex_value_locked(&curval, uaddr1); |
1da177e4 LT |
923 | |
924 | if (unlikely(ret)) { | |
e2970f2f IM |
925 | spin_unlock(&hb1->lock); |
926 | if (hb1 != hb2) | |
927 | spin_unlock(&hb2->lock); | |
1da177e4 | 928 | |
e2970f2f IM |
929 | /* |
930 | * If we would have faulted, release mmap_sem, fault | |
1da177e4 LT |
931 | * it in and start all over again. |
932 | */ | |
36cf3b5c | 933 | futex_unlock_mm(fshared); |
1da177e4 | 934 | |
e2970f2f | 935 | ret = get_user(curval, uaddr1); |
1da177e4 LT |
936 | |
937 | if (!ret) | |
938 | goto retry; | |
939 | ||
940 | return ret; | |
941 | } | |
e2970f2f | 942 | if (curval != *cmpval) { |
1da177e4 LT |
943 | ret = -EAGAIN; |
944 | goto out_unlock; | |
945 | } | |
946 | } | |
947 | ||
e2970f2f | 948 | head1 = &hb1->chain; |
ec92d082 | 949 | plist_for_each_entry_safe(this, next, head1, list) { |
1da177e4 LT |
950 | if (!match_futex (&this->key, &key1)) |
951 | continue; | |
952 | if (++ret <= nr_wake) { | |
953 | wake_futex(this); | |
954 | } else { | |
59e0e0ac SD |
955 | /* |
956 | * If key1 and key2 hash to the same bucket, no need to | |
957 | * requeue. | |
958 | */ | |
959 | if (likely(head1 != &hb2->chain)) { | |
ec92d082 PP |
960 | plist_del(&this->list, &hb1->chain); |
961 | plist_add(&this->list, &hb2->chain); | |
59e0e0ac | 962 | this->lock_ptr = &hb2->lock; |
ec92d082 PP |
963 | #ifdef CONFIG_DEBUG_PI_LIST |
964 | this->list.plist.lock = &hb2->lock; | |
965 | #endif | |
778e9a9c | 966 | } |
1da177e4 | 967 | this->key = key2; |
9adef58b | 968 | get_futex_key_refs(&key2); |
1da177e4 LT |
969 | drop_count++; |
970 | ||
971 | if (ret - nr_wake >= nr_requeue) | |
972 | break; | |
1da177e4 LT |
973 | } |
974 | } | |
975 | ||
976 | out_unlock: | |
e2970f2f IM |
977 | spin_unlock(&hb1->lock); |
978 | if (hb1 != hb2) | |
979 | spin_unlock(&hb2->lock); | |
1da177e4 | 980 | |
9adef58b | 981 | /* drop_futex_key_refs() must be called outside the spinlocks. */ |
1da177e4 | 982 | while (--drop_count >= 0) |
9adef58b | 983 | drop_futex_key_refs(&key1); |
1da177e4 LT |
984 | |
985 | out: | |
36cf3b5c | 986 | futex_unlock_mm(fshared); |
1da177e4 LT |
987 | return ret; |
988 | } | |
989 | ||
990 | /* The key must be already stored in q->key. */ | |
991 | static inline struct futex_hash_bucket * | |
992 | queue_lock(struct futex_q *q, int fd, struct file *filp) | |
993 | { | |
e2970f2f | 994 | struct futex_hash_bucket *hb; |
1da177e4 LT |
995 | |
996 | q->fd = fd; | |
997 | q->filp = filp; | |
998 | ||
999 | init_waitqueue_head(&q->waiters); | |
1000 | ||
9adef58b | 1001 | get_futex_key_refs(&q->key); |
e2970f2f IM |
1002 | hb = hash_futex(&q->key); |
1003 | q->lock_ptr = &hb->lock; | |
1da177e4 | 1004 | |
e2970f2f IM |
1005 | spin_lock(&hb->lock); |
1006 | return hb; | |
1da177e4 LT |
1007 | } |
1008 | ||
e2970f2f | 1009 | static inline void __queue_me(struct futex_q *q, struct futex_hash_bucket *hb) |
1da177e4 | 1010 | { |
ec92d082 PP |
1011 | int prio; |
1012 | ||
1013 | /* | |
1014 | * The priority used to register this element is | |
1015 | * - either the real thread-priority for the real-time threads | |
1016 | * (i.e. threads with a priority lower than MAX_RT_PRIO) | |
1017 | * - or MAX_RT_PRIO for non-RT threads. | |
1018 | * Thus, all RT-threads are woken first in priority order, and | |
1019 | * the others are woken last, in FIFO order. | |
1020 | */ | |
1021 | prio = min(current->normal_prio, MAX_RT_PRIO); | |
1022 | ||
1023 | plist_node_init(&q->list, prio); | |
1024 | #ifdef CONFIG_DEBUG_PI_LIST | |
1025 | q->list.plist.lock = &hb->lock; | |
1026 | #endif | |
1027 | plist_add(&q->list, &hb->chain); | |
c87e2837 | 1028 | q->task = current; |
e2970f2f | 1029 | spin_unlock(&hb->lock); |
1da177e4 LT |
1030 | } |
1031 | ||
1032 | static inline void | |
e2970f2f | 1033 | queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb) |
1da177e4 | 1034 | { |
e2970f2f | 1035 | spin_unlock(&hb->lock); |
9adef58b | 1036 | drop_futex_key_refs(&q->key); |
1da177e4 LT |
1037 | } |
1038 | ||
1039 | /* | |
1040 | * queue_me and unqueue_me must be called as a pair, each | |
1041 | * exactly once. They are called with the hashed spinlock held. | |
1042 | */ | |
1043 | ||
1044 | /* The key must be already stored in q->key. */ | |
1045 | static void queue_me(struct futex_q *q, int fd, struct file *filp) | |
1046 | { | |
e2970f2f IM |
1047 | struct futex_hash_bucket *hb; |
1048 | ||
1049 | hb = queue_lock(q, fd, filp); | |
1050 | __queue_me(q, hb); | |
1da177e4 LT |
1051 | } |
1052 | ||
1053 | /* Return 1 if we were still queued (ie. 0 means we were woken) */ | |
1054 | static int unqueue_me(struct futex_q *q) | |
1055 | { | |
1da177e4 | 1056 | spinlock_t *lock_ptr; |
e2970f2f | 1057 | int ret = 0; |
1da177e4 LT |
1058 | |
1059 | /* In the common case we don't take the spinlock, which is nice. */ | |
1060 | retry: | |
1061 | lock_ptr = q->lock_ptr; | |
e91467ec | 1062 | barrier(); |
c80544dc | 1063 | if (lock_ptr != NULL) { |
1da177e4 LT |
1064 | spin_lock(lock_ptr); |
1065 | /* | |
1066 | * q->lock_ptr can change between reading it and | |
1067 | * spin_lock(), causing us to take the wrong lock. This | |
1068 | * corrects the race condition. | |
1069 | * | |
1070 | * Reasoning goes like this: if we have the wrong lock, | |
1071 | * q->lock_ptr must have changed (maybe several times) | |
1072 | * between reading it and the spin_lock(). It can | |
1073 | * change again after the spin_lock() but only if it was | |
1074 | * already changed before the spin_lock(). It cannot, | |
1075 | * however, change back to the original value. Therefore | |
1076 | * we can detect whether we acquired the correct lock. | |
1077 | */ | |
1078 | if (unlikely(lock_ptr != q->lock_ptr)) { | |
1079 | spin_unlock(lock_ptr); | |
1080 | goto retry; | |
1081 | } | |
ec92d082 PP |
1082 | WARN_ON(plist_node_empty(&q->list)); |
1083 | plist_del(&q->list, &q->list.plist); | |
c87e2837 IM |
1084 | |
1085 | BUG_ON(q->pi_state); | |
1086 | ||
1da177e4 LT |
1087 | spin_unlock(lock_ptr); |
1088 | ret = 1; | |
1089 | } | |
1090 | ||
9adef58b | 1091 | drop_futex_key_refs(&q->key); |
1da177e4 LT |
1092 | return ret; |
1093 | } | |
1094 | ||
c87e2837 IM |
1095 | /* |
1096 | * PI futexes can not be requeued and must remove themself from the | |
d0aa7a70 PP |
1097 | * hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry |
1098 | * and dropped here. | |
c87e2837 | 1099 | */ |
d0aa7a70 | 1100 | static void unqueue_me_pi(struct futex_q *q) |
c87e2837 | 1101 | { |
ec92d082 PP |
1102 | WARN_ON(plist_node_empty(&q->list)); |
1103 | plist_del(&q->list, &q->list.plist); | |
c87e2837 IM |
1104 | |
1105 | BUG_ON(!q->pi_state); | |
1106 | free_pi_state(q->pi_state); | |
1107 | q->pi_state = NULL; | |
1108 | ||
d0aa7a70 | 1109 | spin_unlock(q->lock_ptr); |
c87e2837 | 1110 | |
9adef58b | 1111 | drop_futex_key_refs(&q->key); |
c87e2837 IM |
1112 | } |
1113 | ||
d0aa7a70 | 1114 | /* |
cdf71a10 | 1115 | * Fixup the pi_state owner with the new owner. |
d0aa7a70 | 1116 | * |
778e9a9c AK |
1117 | * Must be called with hash bucket lock held and mm->sem held for non |
1118 | * private futexes. | |
d0aa7a70 | 1119 | */ |
778e9a9c | 1120 | static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, |
cdf71a10 | 1121 | struct task_struct *newowner) |
d0aa7a70 | 1122 | { |
cdf71a10 | 1123 | u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS; |
d0aa7a70 PP |
1124 | struct futex_pi_state *pi_state = q->pi_state; |
1125 | u32 uval, curval, newval; | |
1126 | int ret; | |
1127 | ||
1128 | /* Owner died? */ | |
1129 | if (pi_state->owner != NULL) { | |
1130 | spin_lock_irq(&pi_state->owner->pi_lock); | |
1131 | WARN_ON(list_empty(&pi_state->list)); | |
1132 | list_del_init(&pi_state->list); | |
1133 | spin_unlock_irq(&pi_state->owner->pi_lock); | |
1134 | } else | |
1135 | newtid |= FUTEX_OWNER_DIED; | |
1136 | ||
cdf71a10 | 1137 | pi_state->owner = newowner; |
d0aa7a70 | 1138 | |
cdf71a10 | 1139 | spin_lock_irq(&newowner->pi_lock); |
d0aa7a70 | 1140 | WARN_ON(!list_empty(&pi_state->list)); |
cdf71a10 TG |
1141 | list_add(&pi_state->list, &newowner->pi_state_list); |
1142 | spin_unlock_irq(&newowner->pi_lock); | |
d0aa7a70 | 1143 | |
d0aa7a70 PP |
1144 | /* |
1145 | * We own it, so we have to replace the pending owner | |
1146 | * TID. This must be atomic as we have preserve the | |
1147 | * owner died bit here. | |
1148 | */ | |
778e9a9c AK |
1149 | ret = get_futex_value_locked(&uval, uaddr); |
1150 | ||
d0aa7a70 PP |
1151 | while (!ret) { |
1152 | newval = (uval & FUTEX_OWNER_DIED) | newtid; | |
778e9a9c | 1153 | |
36cf3b5c | 1154 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
778e9a9c | 1155 | |
d0aa7a70 | 1156 | if (curval == -EFAULT) |
778e9a9c | 1157 | ret = -EFAULT; |
d0aa7a70 PP |
1158 | if (curval == uval) |
1159 | break; | |
1160 | uval = curval; | |
1161 | } | |
1162 | return ret; | |
1163 | } | |
1164 | ||
34f01cc1 ED |
1165 | /* |
1166 | * In case we must use restart_block to restart a futex_wait, | |
ce6bd420 | 1167 | * we encode in the 'flags' shared capability |
34f01cc1 | 1168 | */ |
ce6bd420 | 1169 | #define FLAGS_SHARED 1 |
34f01cc1 | 1170 | |
72c1bbf3 | 1171 | static long futex_wait_restart(struct restart_block *restart); |
36cf3b5c | 1172 | |
34f01cc1 | 1173 | static int futex_wait(u32 __user *uaddr, struct rw_semaphore *fshared, |
cd689985 | 1174 | u32 val, ktime_t *abs_time, u32 bitset) |
1da177e4 | 1175 | { |
c87e2837 IM |
1176 | struct task_struct *curr = current; |
1177 | DECLARE_WAITQUEUE(wait, curr); | |
e2970f2f | 1178 | struct futex_hash_bucket *hb; |
1da177e4 | 1179 | struct futex_q q; |
e2970f2f IM |
1180 | u32 uval; |
1181 | int ret; | |
bd197234 | 1182 | struct hrtimer_sleeper t; |
c19384b5 | 1183 | int rem = 0; |
1da177e4 | 1184 | |
cd689985 TG |
1185 | if (!bitset) |
1186 | return -EINVAL; | |
1187 | ||
c87e2837 | 1188 | q.pi_state = NULL; |
cd689985 | 1189 | q.bitset = bitset; |
1da177e4 | 1190 | retry: |
36cf3b5c | 1191 | futex_lock_mm(fshared); |
1da177e4 | 1192 | |
34f01cc1 | 1193 | ret = get_futex_key(uaddr, fshared, &q.key); |
1da177e4 LT |
1194 | if (unlikely(ret != 0)) |
1195 | goto out_release_sem; | |
1196 | ||
e2970f2f | 1197 | hb = queue_lock(&q, -1, NULL); |
1da177e4 LT |
1198 | |
1199 | /* | |
1200 | * Access the page AFTER the futex is queued. | |
1201 | * Order is important: | |
1202 | * | |
1203 | * Userspace waiter: val = var; if (cond(val)) futex_wait(&var, val); | |
1204 | * Userspace waker: if (cond(var)) { var = new; futex_wake(&var); } | |
1205 | * | |
1206 | * The basic logical guarantee of a futex is that it blocks ONLY | |
1207 | * if cond(var) is known to be true at the time of blocking, for | |
1208 | * any cond. If we queued after testing *uaddr, that would open | |
1209 | * a race condition where we could block indefinitely with | |
1210 | * cond(var) false, which would violate the guarantee. | |
1211 | * | |
1212 | * A consequence is that futex_wait() can return zero and absorb | |
1213 | * a wakeup when *uaddr != val on entry to the syscall. This is | |
1214 | * rare, but normal. | |
1215 | * | |
34f01cc1 ED |
1216 | * for shared futexes, we hold the mmap semaphore, so the mapping |
1217 | * cannot have changed since we looked it up in get_futex_key. | |
1da177e4 | 1218 | */ |
e2970f2f | 1219 | ret = get_futex_value_locked(&uval, uaddr); |
1da177e4 LT |
1220 | |
1221 | if (unlikely(ret)) { | |
e2970f2f | 1222 | queue_unlock(&q, hb); |
1da177e4 | 1223 | |
e2970f2f IM |
1224 | /* |
1225 | * If we would have faulted, release mmap_sem, fault it in and | |
1da177e4 LT |
1226 | * start all over again. |
1227 | */ | |
36cf3b5c | 1228 | futex_unlock_mm(fshared); |
1da177e4 | 1229 | |
e2970f2f | 1230 | ret = get_user(uval, uaddr); |
1da177e4 LT |
1231 | |
1232 | if (!ret) | |
1233 | goto retry; | |
1234 | return ret; | |
1235 | } | |
c87e2837 IM |
1236 | ret = -EWOULDBLOCK; |
1237 | if (uval != val) | |
1238 | goto out_unlock_release_sem; | |
1da177e4 LT |
1239 | |
1240 | /* Only actually queue if *uaddr contained val. */ | |
e2970f2f | 1241 | __queue_me(&q, hb); |
1da177e4 LT |
1242 | |
1243 | /* | |
1244 | * Now the futex is queued and we have checked the data, we | |
1245 | * don't want to hold mmap_sem while we sleep. | |
c87e2837 | 1246 | */ |
36cf3b5c | 1247 | futex_unlock_mm(fshared); |
1da177e4 LT |
1248 | |
1249 | /* | |
1250 | * There might have been scheduling since the queue_me(), as we | |
1251 | * cannot hold a spinlock across the get_user() in case it | |
1252 | * faults, and we cannot just set TASK_INTERRUPTIBLE state when | |
1253 | * queueing ourselves into the futex hash. This code thus has to | |
1254 | * rely on the futex_wake() code removing us from hash when it | |
1255 | * wakes us up. | |
1256 | */ | |
1257 | ||
1258 | /* add_wait_queue is the barrier after __set_current_state. */ | |
1259 | __set_current_state(TASK_INTERRUPTIBLE); | |
1260 | add_wait_queue(&q.waiters, &wait); | |
1261 | /* | |
ec92d082 | 1262 | * !plist_node_empty() is safe here without any lock. |
1da177e4 LT |
1263 | * q.lock_ptr != 0 is not safe, because of ordering against wakeup. |
1264 | */ | |
ec92d082 | 1265 | if (likely(!plist_node_empty(&q.list))) { |
c19384b5 PP |
1266 | if (!abs_time) |
1267 | schedule(); | |
1268 | else { | |
1269 | hrtimer_init(&t.timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); | |
1270 | hrtimer_init_sleeper(&t, current); | |
1271 | t.timer.expires = *abs_time; | |
1272 | ||
1273 | hrtimer_start(&t.timer, t.timer.expires, HRTIMER_MODE_ABS); | |
3588a085 PZ |
1274 | if (!hrtimer_active(&t.timer)) |
1275 | t.task = NULL; | |
c19384b5 PP |
1276 | |
1277 | /* | |
1278 | * the timer could have already expired, in which | |
1279 | * case current would be flagged for rescheduling. | |
1280 | * Don't bother calling schedule. | |
1281 | */ | |
1282 | if (likely(t.task)) | |
1283 | schedule(); | |
1284 | ||
1285 | hrtimer_cancel(&t.timer); | |
72c1bbf3 | 1286 | |
c19384b5 PP |
1287 | /* Flag if a timeout occured */ |
1288 | rem = (t.task == NULL); | |
1289 | } | |
72c1bbf3 | 1290 | } |
1da177e4 LT |
1291 | __set_current_state(TASK_RUNNING); |
1292 | ||
1293 | /* | |
1294 | * NOTE: we don't remove ourselves from the waitqueue because | |
1295 | * we are the only user of it. | |
1296 | */ | |
1297 | ||
1298 | /* If we were woken (and unqueued), we succeeded, whatever. */ | |
1299 | if (!unqueue_me(&q)) | |
1300 | return 0; | |
c19384b5 | 1301 | if (rem) |
1da177e4 | 1302 | return -ETIMEDOUT; |
72c1bbf3 | 1303 | |
e2970f2f IM |
1304 | /* |
1305 | * We expect signal_pending(current), but another thread may | |
1306 | * have handled it for us already. | |
1307 | */ | |
c19384b5 | 1308 | if (!abs_time) |
72c1bbf3 NP |
1309 | return -ERESTARTSYS; |
1310 | else { | |
1311 | struct restart_block *restart; | |
1312 | restart = ¤t_thread_info()->restart_block; | |
1313 | restart->fn = futex_wait_restart; | |
ce6bd420 SR |
1314 | restart->futex.uaddr = (u32 *)uaddr; |
1315 | restart->futex.val = val; | |
1316 | restart->futex.time = abs_time->tv64; | |
cd689985 | 1317 | restart->futex.bitset = bitset; |
ce6bd420 SR |
1318 | restart->futex.flags = 0; |
1319 | ||
34f01cc1 | 1320 | if (fshared) |
ce6bd420 | 1321 | restart->futex.flags |= FLAGS_SHARED; |
72c1bbf3 NP |
1322 | return -ERESTART_RESTARTBLOCK; |
1323 | } | |
1da177e4 | 1324 | |
c87e2837 IM |
1325 | out_unlock_release_sem: |
1326 | queue_unlock(&q, hb); | |
1327 | ||
1da177e4 | 1328 | out_release_sem: |
36cf3b5c | 1329 | futex_unlock_mm(fshared); |
c87e2837 IM |
1330 | return ret; |
1331 | } | |
1332 | ||
72c1bbf3 NP |
1333 | |
1334 | static long futex_wait_restart(struct restart_block *restart) | |
1335 | { | |
ce6bd420 | 1336 | u32 __user *uaddr = (u32 __user *)restart->futex.uaddr; |
34f01cc1 | 1337 | struct rw_semaphore *fshared = NULL; |
ce6bd420 | 1338 | ktime_t t; |
72c1bbf3 | 1339 | |
ce6bd420 | 1340 | t.tv64 = restart->futex.time; |
72c1bbf3 | 1341 | restart->fn = do_no_restart_syscall; |
ce6bd420 | 1342 | if (restart->futex.flags & FLAGS_SHARED) |
34f01cc1 | 1343 | fshared = ¤t->mm->mmap_sem; |
cd689985 TG |
1344 | return (long)futex_wait(uaddr, fshared, restart->futex.val, &t, |
1345 | restart->futex.bitset); | |
72c1bbf3 NP |
1346 | } |
1347 | ||
1348 | ||
c87e2837 IM |
1349 | /* |
1350 | * Userspace tried a 0 -> TID atomic transition of the futex value | |
1351 | * and failed. The kernel side here does the whole locking operation: | |
1352 | * if there are waiters then it will block, it does PI, etc. (Due to | |
1353 | * races the kernel might see a 0 value of the futex too.) | |
1354 | */ | |
34f01cc1 ED |
1355 | static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared, |
1356 | int detect, ktime_t *time, int trylock) | |
c87e2837 | 1357 | { |
c5780e97 | 1358 | struct hrtimer_sleeper timeout, *to = NULL; |
c87e2837 IM |
1359 | struct task_struct *curr = current; |
1360 | struct futex_hash_bucket *hb; | |
1361 | u32 uval, newval, curval; | |
1362 | struct futex_q q; | |
778e9a9c | 1363 | int ret, lock_taken, ownerdied = 0, attempt = 0; |
c87e2837 IM |
1364 | |
1365 | if (refill_pi_state_cache()) | |
1366 | return -ENOMEM; | |
1367 | ||
c19384b5 | 1368 | if (time) { |
c5780e97 | 1369 | to = &timeout; |
c9cb2e3d | 1370 | hrtimer_init(&to->timer, CLOCK_REALTIME, HRTIMER_MODE_ABS); |
c5780e97 | 1371 | hrtimer_init_sleeper(to, current); |
c19384b5 | 1372 | to->timer.expires = *time; |
c5780e97 TG |
1373 | } |
1374 | ||
c87e2837 IM |
1375 | q.pi_state = NULL; |
1376 | retry: | |
36cf3b5c | 1377 | futex_lock_mm(fshared); |
c87e2837 | 1378 | |
34f01cc1 | 1379 | ret = get_futex_key(uaddr, fshared, &q.key); |
c87e2837 IM |
1380 | if (unlikely(ret != 0)) |
1381 | goto out_release_sem; | |
1382 | ||
778e9a9c | 1383 | retry_unlocked: |
c87e2837 IM |
1384 | hb = queue_lock(&q, -1, NULL); |
1385 | ||
1386 | retry_locked: | |
778e9a9c | 1387 | ret = lock_taken = 0; |
d0aa7a70 | 1388 | |
c87e2837 IM |
1389 | /* |
1390 | * To avoid races, we attempt to take the lock here again | |
1391 | * (by doing a 0 -> TID atomic cmpxchg), while holding all | |
1392 | * the locks. It will most likely not succeed. | |
1393 | */ | |
b488893a | 1394 | newval = task_pid_vnr(current); |
c87e2837 | 1395 | |
36cf3b5c | 1396 | curval = cmpxchg_futex_value_locked(uaddr, 0, newval); |
c87e2837 IM |
1397 | |
1398 | if (unlikely(curval == -EFAULT)) | |
1399 | goto uaddr_faulted; | |
1400 | ||
778e9a9c AK |
1401 | /* |
1402 | * Detect deadlocks. In case of REQUEUE_PI this is a valid | |
1403 | * situation and we return success to user space. | |
1404 | */ | |
b488893a | 1405 | if (unlikely((curval & FUTEX_TID_MASK) == task_pid_vnr(current))) { |
bd197234 | 1406 | ret = -EDEADLK; |
c87e2837 IM |
1407 | goto out_unlock_release_sem; |
1408 | } | |
1409 | ||
1410 | /* | |
778e9a9c | 1411 | * Surprise - we got the lock. Just return to userspace: |
c87e2837 IM |
1412 | */ |
1413 | if (unlikely(!curval)) | |
1414 | goto out_unlock_release_sem; | |
1415 | ||
1416 | uval = curval; | |
778e9a9c | 1417 | |
d0aa7a70 | 1418 | /* |
778e9a9c AK |
1419 | * Set the WAITERS flag, so the owner will know it has someone |
1420 | * to wake at next unlock | |
d0aa7a70 | 1421 | */ |
778e9a9c AK |
1422 | newval = curval | FUTEX_WAITERS; |
1423 | ||
1424 | /* | |
1425 | * There are two cases, where a futex might have no owner (the | |
bd197234 TG |
1426 | * owner TID is 0): OWNER_DIED. We take over the futex in this |
1427 | * case. We also do an unconditional take over, when the owner | |
1428 | * of the futex died. | |
778e9a9c AK |
1429 | * |
1430 | * This is safe as we are protected by the hash bucket lock ! | |
1431 | */ | |
1432 | if (unlikely(ownerdied || !(curval & FUTEX_TID_MASK))) { | |
bd197234 | 1433 | /* Keep the OWNER_DIED bit */ |
b488893a | 1434 | newval = (curval & ~FUTEX_TID_MASK) | task_pid_vnr(current); |
778e9a9c AK |
1435 | ownerdied = 0; |
1436 | lock_taken = 1; | |
1437 | } | |
c87e2837 | 1438 | |
36cf3b5c | 1439 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
c87e2837 IM |
1440 | |
1441 | if (unlikely(curval == -EFAULT)) | |
1442 | goto uaddr_faulted; | |
1443 | if (unlikely(curval != uval)) | |
1444 | goto retry_locked; | |
1445 | ||
778e9a9c | 1446 | /* |
bd197234 | 1447 | * We took the lock due to owner died take over. |
778e9a9c | 1448 | */ |
bd197234 | 1449 | if (unlikely(lock_taken)) |
d0aa7a70 | 1450 | goto out_unlock_release_sem; |
d0aa7a70 | 1451 | |
c87e2837 IM |
1452 | /* |
1453 | * We dont have the lock. Look up the PI state (or create it if | |
1454 | * we are the first waiter): | |
1455 | */ | |
d0aa7a70 | 1456 | ret = lookup_pi_state(uval, hb, &q.key, &q.pi_state); |
c87e2837 IM |
1457 | |
1458 | if (unlikely(ret)) { | |
778e9a9c | 1459 | switch (ret) { |
c87e2837 | 1460 | |
778e9a9c AK |
1461 | case -EAGAIN: |
1462 | /* | |
1463 | * Task is exiting and we just wait for the | |
1464 | * exit to complete. | |
1465 | */ | |
1466 | queue_unlock(&q, hb); | |
36cf3b5c | 1467 | futex_unlock_mm(fshared); |
778e9a9c AK |
1468 | cond_resched(); |
1469 | goto retry; | |
c87e2837 | 1470 | |
778e9a9c AK |
1471 | case -ESRCH: |
1472 | /* | |
1473 | * No owner found for this futex. Check if the | |
1474 | * OWNER_DIED bit is set to figure out whether | |
1475 | * this is a robust futex or not. | |
1476 | */ | |
1477 | if (get_futex_value_locked(&curval, uaddr)) | |
c87e2837 | 1478 | goto uaddr_faulted; |
778e9a9c AK |
1479 | |
1480 | /* | |
1481 | * We simply start over in case of a robust | |
1482 | * futex. The code above will take the futex | |
1483 | * and return happy. | |
1484 | */ | |
1485 | if (curval & FUTEX_OWNER_DIED) { | |
1486 | ownerdied = 1; | |
c87e2837 | 1487 | goto retry_locked; |
778e9a9c AK |
1488 | } |
1489 | default: | |
1490 | goto out_unlock_release_sem; | |
c87e2837 | 1491 | } |
c87e2837 IM |
1492 | } |
1493 | ||
1494 | /* | |
1495 | * Only actually queue now that the atomic ops are done: | |
1496 | */ | |
1497 | __queue_me(&q, hb); | |
1498 | ||
1499 | /* | |
1500 | * Now the futex is queued and we have checked the data, we | |
1501 | * don't want to hold mmap_sem while we sleep. | |
1502 | */ | |
36cf3b5c | 1503 | futex_unlock_mm(fshared); |
c87e2837 IM |
1504 | |
1505 | WARN_ON(!q.pi_state); | |
1506 | /* | |
1507 | * Block on the PI mutex: | |
1508 | */ | |
1509 | if (!trylock) | |
1510 | ret = rt_mutex_timed_lock(&q.pi_state->pi_mutex, to, 1); | |
1511 | else { | |
1512 | ret = rt_mutex_trylock(&q.pi_state->pi_mutex); | |
1513 | /* Fixup the trylock return value: */ | |
1514 | ret = ret ? 0 : -EWOULDBLOCK; | |
1515 | } | |
1516 | ||
36cf3b5c | 1517 | futex_lock_mm(fshared); |
a99e4e41 | 1518 | spin_lock(q.lock_ptr); |
c87e2837 | 1519 | |
778e9a9c AK |
1520 | if (!ret) { |
1521 | /* | |
1522 | * Got the lock. We might not be the anticipated owner | |
1523 | * if we did a lock-steal - fix up the PI-state in | |
1524 | * that case: | |
1525 | */ | |
1526 | if (q.pi_state->owner != curr) | |
1527 | ret = fixup_pi_state_owner(uaddr, &q, curr); | |
1528 | } else { | |
c87e2837 IM |
1529 | /* |
1530 | * Catch the rare case, where the lock was released | |
778e9a9c AK |
1531 | * when we were on the way back before we locked the |
1532 | * hash bucket. | |
c87e2837 | 1533 | */ |
cdf71a10 TG |
1534 | if (q.pi_state->owner == curr) { |
1535 | /* | |
1536 | * Try to get the rt_mutex now. This might | |
1537 | * fail as some other task acquired the | |
1538 | * rt_mutex after we removed ourself from the | |
1539 | * rt_mutex waiters list. | |
1540 | */ | |
1541 | if (rt_mutex_trylock(&q.pi_state->pi_mutex)) | |
1542 | ret = 0; | |
1543 | else { | |
1544 | /* | |
1545 | * pi_state is incorrect, some other | |
1546 | * task did a lock steal and we | |
1547 | * returned due to timeout or signal | |
1548 | * without taking the rt_mutex. Too | |
1549 | * late. We can access the | |
1550 | * rt_mutex_owner without locking, as | |
1551 | * the other task is now blocked on | |
1552 | * the hash bucket lock. Fix the state | |
1553 | * up. | |
1554 | */ | |
1555 | struct task_struct *owner; | |
1556 | int res; | |
1557 | ||
1558 | owner = rt_mutex_owner(&q.pi_state->pi_mutex); | |
1559 | res = fixup_pi_state_owner(uaddr, &q, owner); | |
1560 | ||
cdf71a10 TG |
1561 | /* propagate -EFAULT, if the fixup failed */ |
1562 | if (res) | |
1563 | ret = res; | |
1564 | } | |
778e9a9c AK |
1565 | } else { |
1566 | /* | |
1567 | * Paranoia check. If we did not take the lock | |
1568 | * in the trylock above, then we should not be | |
1569 | * the owner of the rtmutex, neither the real | |
1570 | * nor the pending one: | |
1571 | */ | |
1572 | if (rt_mutex_owner(&q.pi_state->pi_mutex) == curr) | |
1573 | printk(KERN_ERR "futex_lock_pi: ret = %d " | |
1574 | "pi-mutex: %p pi-state %p\n", ret, | |
1575 | q.pi_state->pi_mutex.owner, | |
1576 | q.pi_state->owner); | |
c87e2837 | 1577 | } |
c87e2837 IM |
1578 | } |
1579 | ||
778e9a9c AK |
1580 | /* Unqueue and drop the lock */ |
1581 | unqueue_me_pi(&q); | |
36cf3b5c | 1582 | futex_unlock_mm(fshared); |
c87e2837 | 1583 | |
c5780e97 | 1584 | return ret != -EINTR ? ret : -ERESTARTNOINTR; |
c87e2837 IM |
1585 | |
1586 | out_unlock_release_sem: | |
1587 | queue_unlock(&q, hb); | |
1588 | ||
1589 | out_release_sem: | |
36cf3b5c | 1590 | futex_unlock_mm(fshared); |
c87e2837 IM |
1591 | return ret; |
1592 | ||
1593 | uaddr_faulted: | |
1594 | /* | |
1595 | * We have to r/w *(int __user *)uaddr, but we can't modify it | |
1596 | * non-atomically. Therefore, if get_user below is not | |
1597 | * enough, we need to handle the fault ourselves, while | |
1598 | * still holding the mmap_sem. | |
778e9a9c AK |
1599 | * |
1600 | * ... and hb->lock. :-) --ANK | |
c87e2837 | 1601 | */ |
778e9a9c AK |
1602 | queue_unlock(&q, hb); |
1603 | ||
c87e2837 | 1604 | if (attempt++) { |
34f01cc1 ED |
1605 | ret = futex_handle_fault((unsigned long)uaddr, fshared, |
1606 | attempt); | |
1607 | if (ret) | |
778e9a9c AK |
1608 | goto out_release_sem; |
1609 | goto retry_unlocked; | |
c87e2837 IM |
1610 | } |
1611 | ||
36cf3b5c | 1612 | futex_unlock_mm(fshared); |
c87e2837 IM |
1613 | |
1614 | ret = get_user(uval, uaddr); | |
1615 | if (!ret && (uval != -EFAULT)) | |
1616 | goto retry; | |
1617 | ||
1618 | return ret; | |
1619 | } | |
1620 | ||
c87e2837 IM |
1621 | /* |
1622 | * Userspace attempted a TID -> 0 atomic transition, and failed. | |
1623 | * This is the in-kernel slowpath: we look up the PI state (if any), | |
1624 | * and do the rt-mutex unlock. | |
1625 | */ | |
34f01cc1 | 1626 | static int futex_unlock_pi(u32 __user *uaddr, struct rw_semaphore *fshared) |
c87e2837 IM |
1627 | { |
1628 | struct futex_hash_bucket *hb; | |
1629 | struct futex_q *this, *next; | |
1630 | u32 uval; | |
ec92d082 | 1631 | struct plist_head *head; |
c87e2837 IM |
1632 | union futex_key key; |
1633 | int ret, attempt = 0; | |
1634 | ||
1635 | retry: | |
1636 | if (get_user(uval, uaddr)) | |
1637 | return -EFAULT; | |
1638 | /* | |
1639 | * We release only a lock we actually own: | |
1640 | */ | |
b488893a | 1641 | if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current)) |
c87e2837 IM |
1642 | return -EPERM; |
1643 | /* | |
1644 | * First take all the futex related locks: | |
1645 | */ | |
36cf3b5c | 1646 | futex_lock_mm(fshared); |
c87e2837 | 1647 | |
34f01cc1 | 1648 | ret = get_futex_key(uaddr, fshared, &key); |
c87e2837 IM |
1649 | if (unlikely(ret != 0)) |
1650 | goto out; | |
1651 | ||
1652 | hb = hash_futex(&key); | |
778e9a9c | 1653 | retry_unlocked: |
c87e2837 IM |
1654 | spin_lock(&hb->lock); |
1655 | ||
c87e2837 IM |
1656 | /* |
1657 | * To avoid races, try to do the TID -> 0 atomic transition | |
1658 | * again. If it succeeds then we can return without waking | |
1659 | * anyone else up: | |
1660 | */ | |
36cf3b5c | 1661 | if (!(uval & FUTEX_OWNER_DIED)) |
b488893a | 1662 | uval = cmpxchg_futex_value_locked(uaddr, task_pid_vnr(current), 0); |
36cf3b5c | 1663 | |
c87e2837 IM |
1664 | |
1665 | if (unlikely(uval == -EFAULT)) | |
1666 | goto pi_faulted; | |
1667 | /* | |
1668 | * Rare case: we managed to release the lock atomically, | |
1669 | * no need to wake anyone else up: | |
1670 | */ | |
b488893a | 1671 | if (unlikely(uval == task_pid_vnr(current))) |
c87e2837 IM |
1672 | goto out_unlock; |
1673 | ||
1674 | /* | |
1675 | * Ok, other tasks may need to be woken up - check waiters | |
1676 | * and do the wakeup if necessary: | |
1677 | */ | |
1678 | head = &hb->chain; | |
1679 | ||
ec92d082 | 1680 | plist_for_each_entry_safe(this, next, head, list) { |
c87e2837 IM |
1681 | if (!match_futex (&this->key, &key)) |
1682 | continue; | |
1683 | ret = wake_futex_pi(uaddr, uval, this); | |
1684 | /* | |
1685 | * The atomic access to the futex value | |
1686 | * generated a pagefault, so retry the | |
1687 | * user-access and the wakeup: | |
1688 | */ | |
1689 | if (ret == -EFAULT) | |
1690 | goto pi_faulted; | |
1691 | goto out_unlock; | |
1692 | } | |
1693 | /* | |
1694 | * No waiters - kernel unlocks the futex: | |
1695 | */ | |
e3f2ddea IM |
1696 | if (!(uval & FUTEX_OWNER_DIED)) { |
1697 | ret = unlock_futex_pi(uaddr, uval); | |
1698 | if (ret == -EFAULT) | |
1699 | goto pi_faulted; | |
1700 | } | |
c87e2837 IM |
1701 | |
1702 | out_unlock: | |
1703 | spin_unlock(&hb->lock); | |
1704 | out: | |
36cf3b5c | 1705 | futex_unlock_mm(fshared); |
c87e2837 IM |
1706 | |
1707 | return ret; | |
1708 | ||
1709 | pi_faulted: | |
1710 | /* | |
1711 | * We have to r/w *(int __user *)uaddr, but we can't modify it | |
1712 | * non-atomically. Therefore, if get_user below is not | |
1713 | * enough, we need to handle the fault ourselves, while | |
1714 | * still holding the mmap_sem. | |
778e9a9c AK |
1715 | * |
1716 | * ... and hb->lock. --ANK | |
c87e2837 | 1717 | */ |
778e9a9c AK |
1718 | spin_unlock(&hb->lock); |
1719 | ||
c87e2837 | 1720 | if (attempt++) { |
34f01cc1 ED |
1721 | ret = futex_handle_fault((unsigned long)uaddr, fshared, |
1722 | attempt); | |
1723 | if (ret) | |
778e9a9c | 1724 | goto out; |
187226f5 | 1725 | uval = 0; |
778e9a9c | 1726 | goto retry_unlocked; |
c87e2837 IM |
1727 | } |
1728 | ||
36cf3b5c | 1729 | futex_unlock_mm(fshared); |
c87e2837 IM |
1730 | |
1731 | ret = get_user(uval, uaddr); | |
1732 | if (!ret && (uval != -EFAULT)) | |
1733 | goto retry; | |
1734 | ||
1da177e4 LT |
1735 | return ret; |
1736 | } | |
1737 | ||
1738 | static int futex_close(struct inode *inode, struct file *filp) | |
1739 | { | |
1740 | struct futex_q *q = filp->private_data; | |
1741 | ||
1742 | unqueue_me(q); | |
1743 | kfree(q); | |
e2970f2f | 1744 | |
1da177e4 LT |
1745 | return 0; |
1746 | } | |
1747 | ||
1748 | /* This is one-shot: once it's gone off you need a new fd */ | |
1749 | static unsigned int futex_poll(struct file *filp, | |
1750 | struct poll_table_struct *wait) | |
1751 | { | |
1752 | struct futex_q *q = filp->private_data; | |
1753 | int ret = 0; | |
1754 | ||
1755 | poll_wait(filp, &q->waiters, wait); | |
1756 | ||
1757 | /* | |
ec92d082 | 1758 | * plist_node_empty() is safe here without any lock. |
1da177e4 LT |
1759 | * q->lock_ptr != 0 is not safe, because of ordering against wakeup. |
1760 | */ | |
ec92d082 | 1761 | if (plist_node_empty(&q->list)) |
1da177e4 LT |
1762 | ret = POLLIN | POLLRDNORM; |
1763 | ||
1764 | return ret; | |
1765 | } | |
1766 | ||
15ad7cdc | 1767 | static const struct file_operations futex_fops = { |
1da177e4 LT |
1768 | .release = futex_close, |
1769 | .poll = futex_poll, | |
1770 | }; | |
1771 | ||
1772 | /* | |
1773 | * Signal allows caller to avoid the race which would occur if they | |
1774 | * set the sigio stuff up afterwards. | |
1775 | */ | |
e2970f2f | 1776 | static int futex_fd(u32 __user *uaddr, int signal) |
1da177e4 LT |
1777 | { |
1778 | struct futex_q *q; | |
1779 | struct file *filp; | |
1780 | int ret, err; | |
34f01cc1 | 1781 | struct rw_semaphore *fshared; |
19c6b6ed AM |
1782 | static unsigned long printk_interval; |
1783 | ||
1784 | if (printk_timed_ratelimit(&printk_interval, 60 * 60 * 1000)) { | |
1785 | printk(KERN_WARNING "Process `%s' used FUTEX_FD, which " | |
36cf3b5c TG |
1786 | "will be removed from the kernel in June 2007\n", |
1787 | current->comm); | |
19c6b6ed | 1788 | } |
1da177e4 LT |
1789 | |
1790 | ret = -EINVAL; | |
7ed20e1a | 1791 | if (!valid_signal(signal)) |
1da177e4 LT |
1792 | goto out; |
1793 | ||
1794 | ret = get_unused_fd(); | |
1795 | if (ret < 0) | |
1796 | goto out; | |
1797 | filp = get_empty_filp(); | |
1798 | if (!filp) { | |
1799 | put_unused_fd(ret); | |
1800 | ret = -ENFILE; | |
1801 | goto out; | |
1802 | } | |
1803 | filp->f_op = &futex_fops; | |
f3a43f3f JJS |
1804 | filp->f_path.mnt = mntget(futex_mnt); |
1805 | filp->f_path.dentry = dget(futex_mnt->mnt_root); | |
1806 | filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping; | |
1da177e4 LT |
1807 | |
1808 | if (signal) { | |
609d7fa9 | 1809 | err = __f_setown(filp, task_pid(current), PIDTYPE_PID, 1); |
1da177e4 | 1810 | if (err < 0) { |
39ed3fde | 1811 | goto error; |
1da177e4 LT |
1812 | } |
1813 | filp->f_owner.signum = signal; | |
1814 | } | |
1815 | ||
1816 | q = kmalloc(sizeof(*q), GFP_KERNEL); | |
1817 | if (!q) { | |
39ed3fde PE |
1818 | err = -ENOMEM; |
1819 | goto error; | |
1da177e4 | 1820 | } |
c87e2837 | 1821 | q->pi_state = NULL; |
1da177e4 | 1822 | |
34f01cc1 ED |
1823 | fshared = ¤t->mm->mmap_sem; |
1824 | down_read(fshared); | |
1825 | err = get_futex_key(uaddr, fshared, &q->key); | |
1da177e4 LT |
1826 | |
1827 | if (unlikely(err != 0)) { | |
34f01cc1 | 1828 | up_read(fshared); |
1da177e4 | 1829 | kfree(q); |
39ed3fde | 1830 | goto error; |
1da177e4 LT |
1831 | } |
1832 | ||
1833 | /* | |
1834 | * queue_me() must be called before releasing mmap_sem, because | |
1835 | * key->shared.inode needs to be referenced while holding it. | |
1836 | */ | |
1837 | filp->private_data = q; | |
1838 | ||
1839 | queue_me(q, ret, filp); | |
34f01cc1 | 1840 | up_read(fshared); |
1da177e4 LT |
1841 | |
1842 | /* Now we map fd to filp, so userspace can access it */ | |
1843 | fd_install(ret, filp); | |
1844 | out: | |
1845 | return ret; | |
39ed3fde PE |
1846 | error: |
1847 | put_unused_fd(ret); | |
1848 | put_filp(filp); | |
1849 | ret = err; | |
1850 | goto out; | |
1da177e4 LT |
1851 | } |
1852 | ||
0771dfef IM |
1853 | /* |
1854 | * Support for robust futexes: the kernel cleans up held futexes at | |
1855 | * thread exit time. | |
1856 | * | |
1857 | * Implementation: user-space maintains a per-thread list of locks it | |
1858 | * is holding. Upon do_exit(), the kernel carefully walks this list, | |
1859 | * and marks all locks that are owned by this thread with the | |
c87e2837 | 1860 | * FUTEX_OWNER_DIED bit, and wakes up a waiter (if any). The list is |
0771dfef IM |
1861 | * always manipulated with the lock held, so the list is private and |
1862 | * per-thread. Userspace also maintains a per-thread 'list_op_pending' | |
1863 | * field, to allow the kernel to clean up if the thread dies after | |
1864 | * acquiring the lock, but just before it could have added itself to | |
1865 | * the list. There can only be one such pending lock. | |
1866 | */ | |
1867 | ||
1868 | /** | |
1869 | * sys_set_robust_list - set the robust-futex list head of a task | |
1870 | * @head: pointer to the list-head | |
1871 | * @len: length of the list-head, as userspace expects | |
1872 | */ | |
1873 | asmlinkage long | |
1874 | sys_set_robust_list(struct robust_list_head __user *head, | |
1875 | size_t len) | |
1876 | { | |
a0c1e907 TG |
1877 | if (!futex_cmpxchg_enabled) |
1878 | return -ENOSYS; | |
0771dfef IM |
1879 | /* |
1880 | * The kernel knows only one size for now: | |
1881 | */ | |
1882 | if (unlikely(len != sizeof(*head))) | |
1883 | return -EINVAL; | |
1884 | ||
1885 | current->robust_list = head; | |
1886 | ||
1887 | return 0; | |
1888 | } | |
1889 | ||
1890 | /** | |
1891 | * sys_get_robust_list - get the robust-futex list head of a task | |
1892 | * @pid: pid of the process [zero for current task] | |
1893 | * @head_ptr: pointer to a list-head pointer, the kernel fills it in | |
1894 | * @len_ptr: pointer to a length field, the kernel fills in the header size | |
1895 | */ | |
1896 | asmlinkage long | |
ba46df98 | 1897 | sys_get_robust_list(int pid, struct robust_list_head __user * __user *head_ptr, |
0771dfef IM |
1898 | size_t __user *len_ptr) |
1899 | { | |
ba46df98 | 1900 | struct robust_list_head __user *head; |
0771dfef IM |
1901 | unsigned long ret; |
1902 | ||
a0c1e907 TG |
1903 | if (!futex_cmpxchg_enabled) |
1904 | return -ENOSYS; | |
1905 | ||
0771dfef IM |
1906 | if (!pid) |
1907 | head = current->robust_list; | |
1908 | else { | |
1909 | struct task_struct *p; | |
1910 | ||
1911 | ret = -ESRCH; | |
aaa2a97e | 1912 | rcu_read_lock(); |
228ebcbe | 1913 | p = find_task_by_vpid(pid); |
0771dfef IM |
1914 | if (!p) |
1915 | goto err_unlock; | |
1916 | ret = -EPERM; | |
1917 | if ((current->euid != p->euid) && (current->euid != p->uid) && | |
1918 | !capable(CAP_SYS_PTRACE)) | |
1919 | goto err_unlock; | |
1920 | head = p->robust_list; | |
aaa2a97e | 1921 | rcu_read_unlock(); |
0771dfef IM |
1922 | } |
1923 | ||
1924 | if (put_user(sizeof(*head), len_ptr)) | |
1925 | return -EFAULT; | |
1926 | return put_user(head, head_ptr); | |
1927 | ||
1928 | err_unlock: | |
aaa2a97e | 1929 | rcu_read_unlock(); |
0771dfef IM |
1930 | |
1931 | return ret; | |
1932 | } | |
1933 | ||
1934 | /* | |
1935 | * Process a futex-list entry, check whether it's owned by the | |
1936 | * dying task, and do notification if so: | |
1937 | */ | |
e3f2ddea | 1938 | int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi) |
0771dfef | 1939 | { |
e3f2ddea | 1940 | u32 uval, nval, mval; |
0771dfef | 1941 | |
8f17d3a5 IM |
1942 | retry: |
1943 | if (get_user(uval, uaddr)) | |
0771dfef IM |
1944 | return -1; |
1945 | ||
b488893a | 1946 | if ((uval & FUTEX_TID_MASK) == task_pid_vnr(curr)) { |
0771dfef IM |
1947 | /* |
1948 | * Ok, this dying thread is truly holding a futex | |
1949 | * of interest. Set the OWNER_DIED bit atomically | |
1950 | * via cmpxchg, and if the value had FUTEX_WAITERS | |
1951 | * set, wake up a waiter (if any). (We have to do a | |
1952 | * futex_wake() even if OWNER_DIED is already set - | |
1953 | * to handle the rare but possible case of recursive | |
1954 | * thread-death.) The rest of the cleanup is done in | |
1955 | * userspace. | |
1956 | */ | |
e3f2ddea IM |
1957 | mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; |
1958 | nval = futex_atomic_cmpxchg_inatomic(uaddr, uval, mval); | |
1959 | ||
c87e2837 IM |
1960 | if (nval == -EFAULT) |
1961 | return -1; | |
1962 | ||
1963 | if (nval != uval) | |
8f17d3a5 | 1964 | goto retry; |
0771dfef | 1965 | |
e3f2ddea IM |
1966 | /* |
1967 | * Wake robust non-PI futexes here. The wakeup of | |
1968 | * PI futexes happens in exit_pi_state(): | |
1969 | */ | |
36cf3b5c | 1970 | if (!pi && (uval & FUTEX_WAITERS)) |
cd689985 TG |
1971 | futex_wake(uaddr, &curr->mm->mmap_sem, 1, |
1972 | FUTEX_BITSET_MATCH_ANY); | |
0771dfef IM |
1973 | } |
1974 | return 0; | |
1975 | } | |
1976 | ||
e3f2ddea IM |
1977 | /* |
1978 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: | |
1979 | */ | |
1980 | static inline int fetch_robust_entry(struct robust_list __user **entry, | |
ba46df98 AV |
1981 | struct robust_list __user * __user *head, |
1982 | int *pi) | |
e3f2ddea IM |
1983 | { |
1984 | unsigned long uentry; | |
1985 | ||
ba46df98 | 1986 | if (get_user(uentry, (unsigned long __user *)head)) |
e3f2ddea IM |
1987 | return -EFAULT; |
1988 | ||
ba46df98 | 1989 | *entry = (void __user *)(uentry & ~1UL); |
e3f2ddea IM |
1990 | *pi = uentry & 1; |
1991 | ||
1992 | return 0; | |
1993 | } | |
1994 | ||
0771dfef IM |
1995 | /* |
1996 | * Walk curr->robust_list (very carefully, it's a userspace list!) | |
1997 | * and mark any locks found there dead, and notify any waiters. | |
1998 | * | |
1999 | * We silently return on any sign of list-walking problem. | |
2000 | */ | |
2001 | void exit_robust_list(struct task_struct *curr) | |
2002 | { | |
2003 | struct robust_list_head __user *head = curr->robust_list; | |
9f96cb1e MS |
2004 | struct robust_list __user *entry, *next_entry, *pending; |
2005 | unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip; | |
0771dfef | 2006 | unsigned long futex_offset; |
9f96cb1e | 2007 | int rc; |
0771dfef | 2008 | |
a0c1e907 TG |
2009 | if (!futex_cmpxchg_enabled) |
2010 | return; | |
2011 | ||
0771dfef IM |
2012 | /* |
2013 | * Fetch the list head (which was registered earlier, via | |
2014 | * sys_set_robust_list()): | |
2015 | */ | |
e3f2ddea | 2016 | if (fetch_robust_entry(&entry, &head->list.next, &pi)) |
0771dfef IM |
2017 | return; |
2018 | /* | |
2019 | * Fetch the relative futex offset: | |
2020 | */ | |
2021 | if (get_user(futex_offset, &head->futex_offset)) | |
2022 | return; | |
2023 | /* | |
2024 | * Fetch any possibly pending lock-add first, and handle it | |
2025 | * if it exists: | |
2026 | */ | |
e3f2ddea | 2027 | if (fetch_robust_entry(&pending, &head->list_op_pending, &pip)) |
0771dfef | 2028 | return; |
e3f2ddea | 2029 | |
9f96cb1e | 2030 | next_entry = NULL; /* avoid warning with gcc */ |
0771dfef | 2031 | while (entry != &head->list) { |
9f96cb1e MS |
2032 | /* |
2033 | * Fetch the next entry in the list before calling | |
2034 | * handle_futex_death: | |
2035 | */ | |
2036 | rc = fetch_robust_entry(&next_entry, &entry->next, &next_pi); | |
0771dfef IM |
2037 | /* |
2038 | * A pending lock might already be on the list, so | |
c87e2837 | 2039 | * don't process it twice: |
0771dfef IM |
2040 | */ |
2041 | if (entry != pending) | |
ba46df98 | 2042 | if (handle_futex_death((void __user *)entry + futex_offset, |
e3f2ddea | 2043 | curr, pi)) |
0771dfef | 2044 | return; |
9f96cb1e | 2045 | if (rc) |
0771dfef | 2046 | return; |
9f96cb1e MS |
2047 | entry = next_entry; |
2048 | pi = next_pi; | |
0771dfef IM |
2049 | /* |
2050 | * Avoid excessively long or circular lists: | |
2051 | */ | |
2052 | if (!--limit) | |
2053 | break; | |
2054 | ||
2055 | cond_resched(); | |
2056 | } | |
9f96cb1e MS |
2057 | |
2058 | if (pending) | |
2059 | handle_futex_death((void __user *)pending + futex_offset, | |
2060 | curr, pip); | |
0771dfef IM |
2061 | } |
2062 | ||
c19384b5 | 2063 | long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, |
e2970f2f | 2064 | u32 __user *uaddr2, u32 val2, u32 val3) |
1da177e4 | 2065 | { |
a0c1e907 | 2066 | int ret = -ENOSYS; |
34f01cc1 ED |
2067 | int cmd = op & FUTEX_CMD_MASK; |
2068 | struct rw_semaphore *fshared = NULL; | |
2069 | ||
2070 | if (!(op & FUTEX_PRIVATE_FLAG)) | |
2071 | fshared = ¤t->mm->mmap_sem; | |
1da177e4 | 2072 | |
34f01cc1 | 2073 | switch (cmd) { |
1da177e4 | 2074 | case FUTEX_WAIT: |
cd689985 TG |
2075 | val3 = FUTEX_BITSET_MATCH_ANY; |
2076 | case FUTEX_WAIT_BITSET: | |
2077 | ret = futex_wait(uaddr, fshared, val, timeout, val3); | |
1da177e4 LT |
2078 | break; |
2079 | case FUTEX_WAKE: | |
cd689985 TG |
2080 | val3 = FUTEX_BITSET_MATCH_ANY; |
2081 | case FUTEX_WAKE_BITSET: | |
2082 | ret = futex_wake(uaddr, fshared, val, val3); | |
1da177e4 LT |
2083 | break; |
2084 | case FUTEX_FD: | |
2085 | /* non-zero val means F_SETOWN(getpid()) & F_SETSIG(val) */ | |
2086 | ret = futex_fd(uaddr, val); | |
2087 | break; | |
2088 | case FUTEX_REQUEUE: | |
34f01cc1 | 2089 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL); |
1da177e4 LT |
2090 | break; |
2091 | case FUTEX_CMP_REQUEUE: | |
34f01cc1 | 2092 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3); |
1da177e4 | 2093 | break; |
4732efbe | 2094 | case FUTEX_WAKE_OP: |
34f01cc1 | 2095 | ret = futex_wake_op(uaddr, fshared, uaddr2, val, val2, val3); |
4732efbe | 2096 | break; |
c87e2837 | 2097 | case FUTEX_LOCK_PI: |
a0c1e907 TG |
2098 | if (futex_cmpxchg_enabled) |
2099 | ret = futex_lock_pi(uaddr, fshared, val, timeout, 0); | |
c87e2837 IM |
2100 | break; |
2101 | case FUTEX_UNLOCK_PI: | |
a0c1e907 TG |
2102 | if (futex_cmpxchg_enabled) |
2103 | ret = futex_unlock_pi(uaddr, fshared); | |
c87e2837 IM |
2104 | break; |
2105 | case FUTEX_TRYLOCK_PI: | |
a0c1e907 TG |
2106 | if (futex_cmpxchg_enabled) |
2107 | ret = futex_lock_pi(uaddr, fshared, 0, timeout, 1); | |
c87e2837 | 2108 | break; |
1da177e4 LT |
2109 | default: |
2110 | ret = -ENOSYS; | |
2111 | } | |
2112 | return ret; | |
2113 | } | |
2114 | ||
2115 | ||
e2970f2f | 2116 | asmlinkage long sys_futex(u32 __user *uaddr, int op, u32 val, |
1da177e4 | 2117 | struct timespec __user *utime, u32 __user *uaddr2, |
e2970f2f | 2118 | u32 val3) |
1da177e4 | 2119 | { |
c19384b5 PP |
2120 | struct timespec ts; |
2121 | ktime_t t, *tp = NULL; | |
e2970f2f | 2122 | u32 val2 = 0; |
34f01cc1 | 2123 | int cmd = op & FUTEX_CMD_MASK; |
1da177e4 | 2124 | |
cd689985 TG |
2125 | if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
2126 | cmd == FUTEX_WAIT_BITSET)) { | |
c19384b5 | 2127 | if (copy_from_user(&ts, utime, sizeof(ts)) != 0) |
1da177e4 | 2128 | return -EFAULT; |
c19384b5 | 2129 | if (!timespec_valid(&ts)) |
9741ef96 | 2130 | return -EINVAL; |
c19384b5 PP |
2131 | |
2132 | t = timespec_to_ktime(ts); | |
34f01cc1 | 2133 | if (cmd == FUTEX_WAIT) |
5a7780e7 | 2134 | t = ktime_add_safe(ktime_get(), t); |
c19384b5 | 2135 | tp = &t; |
1da177e4 LT |
2136 | } |
2137 | /* | |
34f01cc1 | 2138 | * requeue parameter in 'utime' if cmd == FUTEX_REQUEUE. |
f54f0986 | 2139 | * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP. |
1da177e4 | 2140 | */ |
f54f0986 AS |
2141 | if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
2142 | cmd == FUTEX_WAKE_OP) | |
e2970f2f | 2143 | val2 = (u32) (unsigned long) utime; |
1da177e4 | 2144 | |
c19384b5 | 2145 | return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
1da177e4 LT |
2146 | } |
2147 | ||
454e2398 DH |
2148 | static int futexfs_get_sb(struct file_system_type *fs_type, |
2149 | int flags, const char *dev_name, void *data, | |
2150 | struct vfsmount *mnt) | |
1da177e4 | 2151 | { |
fd5eea42 | 2152 | return get_sb_pseudo(fs_type, "futex", NULL, FUTEXFS_SUPER_MAGIC, mnt); |
1da177e4 LT |
2153 | } |
2154 | ||
2155 | static struct file_system_type futex_fs_type = { | |
2156 | .name = "futexfs", | |
2157 | .get_sb = futexfs_get_sb, | |
2158 | .kill_sb = kill_anon_super, | |
2159 | }; | |
2160 | ||
f6d107fb | 2161 | static int __init futex_init(void) |
1da177e4 | 2162 | { |
a0c1e907 | 2163 | u32 curval; |
3e4ab747 | 2164 | int i; |
95362fa9 | 2165 | |
a0c1e907 TG |
2166 | /* |
2167 | * This will fail and we want it. Some arch implementations do | |
2168 | * runtime detection of the futex_atomic_cmpxchg_inatomic() | |
2169 | * functionality. We want to know that before we call in any | |
2170 | * of the complex code paths. Also we want to prevent | |
2171 | * registration of robust lists in that case. NULL is | |
2172 | * guaranteed to fault and we get -EFAULT on functional | |
2173 | * implementation, the non functional ones will return | |
2174 | * -ENOSYS. | |
2175 | */ | |
2176 | curval = cmpxchg_futex_value_locked(NULL, 0, 0); | |
2177 | if (curval == -EFAULT) | |
2178 | futex_cmpxchg_enabled = 1; | |
2179 | ||
3e4ab747 TG |
2180 | for (i = 0; i < ARRAY_SIZE(futex_queues); i++) { |
2181 | plist_head_init(&futex_queues[i].chain, &futex_queues[i].lock); | |
2182 | spin_lock_init(&futex_queues[i].lock); | |
2183 | } | |
2184 | ||
2185 | i = register_filesystem(&futex_fs_type); | |
95362fa9 AM |
2186 | if (i) |
2187 | return i; | |
1da177e4 | 2188 | |
1da177e4 | 2189 | futex_mnt = kern_mount(&futex_fs_type); |
95362fa9 AM |
2190 | if (IS_ERR(futex_mnt)) { |
2191 | unregister_filesystem(&futex_fs_type); | |
2192 | return PTR_ERR(futex_mnt); | |
2193 | } | |
1da177e4 | 2194 | |
1da177e4 LT |
2195 | return 0; |
2196 | } | |
f6d107fb | 2197 | __initcall(futex_init); |