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 | * | |
1da177e4 LT |
19 | * Thanks to Ben LaHaise for yelling "hashed waitqueues" loudly |
20 | * enough at me, Linus for the original (flawed) idea, Matthew | |
21 | * Kirkwood for proof-of-concept implementation. | |
22 | * | |
23 | * "The futexes are also cursed." | |
24 | * "But they come in a choice of three flavours!" | |
25 | * | |
26 | * This program is free software; you can redistribute it and/or modify | |
27 | * it under the terms of the GNU General Public License as published by | |
28 | * the Free Software Foundation; either version 2 of the License, or | |
29 | * (at your option) any later version. | |
30 | * | |
31 | * This program is distributed in the hope that it will be useful, | |
32 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
33 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
34 | * GNU General Public License for more details. | |
35 | * | |
36 | * You should have received a copy of the GNU General Public License | |
37 | * along with this program; if not, write to the Free Software | |
38 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
39 | */ | |
40 | #include <linux/slab.h> | |
41 | #include <linux/poll.h> | |
42 | #include <linux/fs.h> | |
43 | #include <linux/file.h> | |
44 | #include <linux/jhash.h> | |
45 | #include <linux/init.h> | |
46 | #include <linux/futex.h> | |
47 | #include <linux/mount.h> | |
48 | #include <linux/pagemap.h> | |
49 | #include <linux/syscalls.h> | |
7ed20e1a | 50 | #include <linux/signal.h> |
9adef58b | 51 | #include <linux/module.h> |
4732efbe | 52 | #include <asm/futex.h> |
1da177e4 | 53 | |
c87e2837 IM |
54 | #include "rtmutex_common.h" |
55 | ||
1da177e4 LT |
56 | #define FUTEX_HASHBITS (CONFIG_BASE_SMALL ? 4 : 8) |
57 | ||
c87e2837 IM |
58 | /* |
59 | * Priority Inheritance state: | |
60 | */ | |
61 | struct futex_pi_state { | |
62 | /* | |
63 | * list of 'owned' pi_state instances - these have to be | |
64 | * cleaned up in do_exit() if the task exits prematurely: | |
65 | */ | |
66 | struct list_head list; | |
67 | ||
68 | /* | |
69 | * The PI object: | |
70 | */ | |
71 | struct rt_mutex pi_mutex; | |
72 | ||
73 | struct task_struct *owner; | |
74 | atomic_t refcount; | |
75 | ||
76 | union futex_key key; | |
77 | }; | |
78 | ||
1da177e4 LT |
79 | /* |
80 | * We use this hashed waitqueue instead of a normal wait_queue_t, so | |
81 | * we can wake only the relevant ones (hashed queues may be shared). | |
82 | * | |
83 | * A futex_q has a woken state, just like tasks have TASK_RUNNING. | |
84 | * It is considered woken when list_empty(&q->list) || q->lock_ptr == 0. | |
85 | * The order of wakup is always to make the first condition true, then | |
86 | * wake up q->waiters, then make the second condition true. | |
87 | */ | |
88 | struct futex_q { | |
89 | struct list_head list; | |
90 | wait_queue_head_t waiters; | |
91 | ||
e2970f2f | 92 | /* Which hash list lock to use: */ |
1da177e4 LT |
93 | spinlock_t *lock_ptr; |
94 | ||
e2970f2f | 95 | /* Key which the futex is hashed on: */ |
1da177e4 LT |
96 | union futex_key key; |
97 | ||
e2970f2f | 98 | /* For fd, sigio sent using these: */ |
1da177e4 LT |
99 | int fd; |
100 | struct file *filp; | |
c87e2837 IM |
101 | |
102 | /* Optional priority inheritance state: */ | |
103 | struct futex_pi_state *pi_state; | |
104 | struct task_struct *task; | |
1da177e4 LT |
105 | }; |
106 | ||
107 | /* | |
108 | * Split the global futex_lock into every hash list lock. | |
109 | */ | |
110 | struct futex_hash_bucket { | |
111 | spinlock_t lock; | |
112 | struct list_head chain; | |
113 | }; | |
114 | ||
115 | static struct futex_hash_bucket futex_queues[1<<FUTEX_HASHBITS]; | |
116 | ||
117 | /* Futex-fs vfsmount entry: */ | |
118 | static struct vfsmount *futex_mnt; | |
119 | ||
120 | /* | |
121 | * We hash on the keys returned from get_futex_key (see below). | |
122 | */ | |
123 | static struct futex_hash_bucket *hash_futex(union futex_key *key) | |
124 | { | |
125 | u32 hash = jhash2((u32*)&key->both.word, | |
126 | (sizeof(key->both.word)+sizeof(key->both.ptr))/4, | |
127 | key->both.offset); | |
128 | return &futex_queues[hash & ((1 << FUTEX_HASHBITS)-1)]; | |
129 | } | |
130 | ||
131 | /* | |
132 | * Return 1 if two futex_keys are equal, 0 otherwise. | |
133 | */ | |
134 | static inline int match_futex(union futex_key *key1, union futex_key *key2) | |
135 | { | |
136 | return (key1->both.word == key2->both.word | |
137 | && key1->both.ptr == key2->both.ptr | |
138 | && key1->both.offset == key2->both.offset); | |
139 | } | |
140 | ||
141 | /* | |
142 | * Get parameters which are the keys for a futex. | |
143 | * | |
f3a43f3f | 144 | * For shared mappings, it's (page->index, vma->vm_file->f_path.dentry->d_inode, |
1da177e4 LT |
145 | * offset_within_page). For private mappings, it's (uaddr, current->mm). |
146 | * We can usually work out the index without swapping in the page. | |
147 | * | |
148 | * Returns: 0, or negative error code. | |
149 | * The key words are stored in *key on success. | |
150 | * | |
151 | * Should be called with ¤t->mm->mmap_sem but NOT any spinlocks. | |
152 | */ | |
9adef58b | 153 | int get_futex_key(u32 __user *uaddr, union futex_key *key) |
1da177e4 | 154 | { |
e2970f2f | 155 | unsigned long address = (unsigned long)uaddr; |
1da177e4 LT |
156 | struct mm_struct *mm = current->mm; |
157 | struct vm_area_struct *vma; | |
158 | struct page *page; | |
159 | int err; | |
160 | ||
161 | /* | |
162 | * The futex address must be "naturally" aligned. | |
163 | */ | |
e2970f2f | 164 | key->both.offset = address % PAGE_SIZE; |
1da177e4 LT |
165 | if (unlikely((key->both.offset % sizeof(u32)) != 0)) |
166 | return -EINVAL; | |
e2970f2f | 167 | address -= key->both.offset; |
1da177e4 LT |
168 | |
169 | /* | |
170 | * The futex is hashed differently depending on whether | |
171 | * it's in a shared or private mapping. So check vma first. | |
172 | */ | |
e2970f2f | 173 | vma = find_extend_vma(mm, address); |
1da177e4 LT |
174 | if (unlikely(!vma)) |
175 | return -EFAULT; | |
176 | ||
177 | /* | |
178 | * Permissions. | |
179 | */ | |
180 | if (unlikely((vma->vm_flags & (VM_IO|VM_READ)) != VM_READ)) | |
181 | return (vma->vm_flags & VM_IO) ? -EPERM : -EACCES; | |
182 | ||
183 | /* | |
184 | * Private mappings are handled in a simple way. | |
185 | * | |
186 | * NOTE: When userspace waits on a MAP_SHARED mapping, even if | |
187 | * it's a read-only handle, it's expected that futexes attach to | |
188 | * the object not the particular process. Therefore we use | |
189 | * VM_MAYSHARE here, not VM_SHARED which is restricted to shared | |
190 | * mappings of _writable_ handles. | |
191 | */ | |
192 | if (likely(!(vma->vm_flags & VM_MAYSHARE))) { | |
193 | key->private.mm = mm; | |
e2970f2f | 194 | key->private.address = address; |
1da177e4 LT |
195 | return 0; |
196 | } | |
197 | ||
198 | /* | |
199 | * Linear file mappings are also simple. | |
200 | */ | |
f3a43f3f | 201 | key->shared.inode = vma->vm_file->f_path.dentry->d_inode; |
1da177e4 LT |
202 | key->both.offset++; /* Bit 0 of offset indicates inode-based key. */ |
203 | if (likely(!(vma->vm_flags & VM_NONLINEAR))) { | |
e2970f2f | 204 | key->shared.pgoff = (((address - vma->vm_start) >> PAGE_SHIFT) |
1da177e4 LT |
205 | + vma->vm_pgoff); |
206 | return 0; | |
207 | } | |
208 | ||
209 | /* | |
210 | * We could walk the page table to read the non-linear | |
211 | * pte, and get the page index without fetching the page | |
212 | * from swap. But that's a lot of code to duplicate here | |
213 | * for a rare case, so we simply fetch the page. | |
214 | */ | |
e2970f2f | 215 | err = get_user_pages(current, mm, address, 1, 0, 0, &page, NULL); |
1da177e4 LT |
216 | if (err >= 0) { |
217 | key->shared.pgoff = | |
218 | page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
219 | put_page(page); | |
220 | return 0; | |
221 | } | |
222 | return err; | |
223 | } | |
9adef58b | 224 | EXPORT_SYMBOL_GPL(get_futex_key); |
1da177e4 LT |
225 | |
226 | /* | |
227 | * Take a reference to the resource addressed by a key. | |
228 | * Can be called while holding spinlocks. | |
229 | * | |
230 | * NOTE: mmap_sem MUST be held between get_futex_key() and calling this | |
231 | * function, if it is called at all. mmap_sem keeps key->shared.inode valid. | |
232 | */ | |
9adef58b | 233 | inline void get_futex_key_refs(union futex_key *key) |
1da177e4 LT |
234 | { |
235 | if (key->both.ptr != 0) { | |
236 | if (key->both.offset & 1) | |
237 | atomic_inc(&key->shared.inode->i_count); | |
238 | else | |
239 | atomic_inc(&key->private.mm->mm_count); | |
240 | } | |
241 | } | |
9adef58b | 242 | EXPORT_SYMBOL_GPL(get_futex_key_refs); |
1da177e4 LT |
243 | |
244 | /* | |
245 | * Drop a reference to the resource addressed by a key. | |
246 | * The hash bucket spinlock must not be held. | |
247 | */ | |
9adef58b | 248 | void drop_futex_key_refs(union futex_key *key) |
1da177e4 LT |
249 | { |
250 | if (key->both.ptr != 0) { | |
251 | if (key->both.offset & 1) | |
252 | iput(key->shared.inode); | |
253 | else | |
254 | mmdrop(key->private.mm); | |
255 | } | |
256 | } | |
9adef58b | 257 | EXPORT_SYMBOL_GPL(drop_futex_key_refs); |
1da177e4 | 258 | |
e2970f2f | 259 | static inline int get_futex_value_locked(u32 *dest, u32 __user *from) |
1da177e4 LT |
260 | { |
261 | int ret; | |
262 | ||
a866374a | 263 | pagefault_disable(); |
e2970f2f | 264 | ret = __copy_from_user_inatomic(dest, from, sizeof(u32)); |
a866374a | 265 | pagefault_enable(); |
1da177e4 LT |
266 | |
267 | return ret ? -EFAULT : 0; | |
268 | } | |
269 | ||
c87e2837 IM |
270 | /* |
271 | * Fault handling. Called with current->mm->mmap_sem held. | |
272 | */ | |
273 | static int futex_handle_fault(unsigned long address, int attempt) | |
274 | { | |
275 | struct vm_area_struct * vma; | |
276 | struct mm_struct *mm = current->mm; | |
277 | ||
e579dcbf | 278 | if (attempt > 2 || !(vma = find_vma(mm, address)) || |
c87e2837 IM |
279 | vma->vm_start > address || !(vma->vm_flags & VM_WRITE)) |
280 | return -EFAULT; | |
281 | ||
282 | switch (handle_mm_fault(mm, vma, address, 1)) { | |
283 | case VM_FAULT_MINOR: | |
284 | current->min_flt++; | |
285 | break; | |
286 | case VM_FAULT_MAJOR: | |
287 | current->maj_flt++; | |
288 | break; | |
289 | default: | |
290 | return -EFAULT; | |
291 | } | |
292 | return 0; | |
293 | } | |
294 | ||
295 | /* | |
296 | * PI code: | |
297 | */ | |
298 | static int refill_pi_state_cache(void) | |
299 | { | |
300 | struct futex_pi_state *pi_state; | |
301 | ||
302 | if (likely(current->pi_state_cache)) | |
303 | return 0; | |
304 | ||
4668edc3 | 305 | pi_state = kzalloc(sizeof(*pi_state), GFP_KERNEL); |
c87e2837 IM |
306 | |
307 | if (!pi_state) | |
308 | return -ENOMEM; | |
309 | ||
c87e2837 IM |
310 | INIT_LIST_HEAD(&pi_state->list); |
311 | /* pi_mutex gets initialized later */ | |
312 | pi_state->owner = NULL; | |
313 | atomic_set(&pi_state->refcount, 1); | |
314 | ||
315 | current->pi_state_cache = pi_state; | |
316 | ||
317 | return 0; | |
318 | } | |
319 | ||
320 | static struct futex_pi_state * alloc_pi_state(void) | |
321 | { | |
322 | struct futex_pi_state *pi_state = current->pi_state_cache; | |
323 | ||
324 | WARN_ON(!pi_state); | |
325 | current->pi_state_cache = NULL; | |
326 | ||
327 | return pi_state; | |
328 | } | |
329 | ||
330 | static void free_pi_state(struct futex_pi_state *pi_state) | |
331 | { | |
332 | if (!atomic_dec_and_test(&pi_state->refcount)) | |
333 | return; | |
334 | ||
335 | /* | |
336 | * If pi_state->owner is NULL, the owner is most probably dying | |
337 | * and has cleaned up the pi_state already | |
338 | */ | |
339 | if (pi_state->owner) { | |
340 | spin_lock_irq(&pi_state->owner->pi_lock); | |
341 | list_del_init(&pi_state->list); | |
342 | spin_unlock_irq(&pi_state->owner->pi_lock); | |
343 | ||
344 | rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner); | |
345 | } | |
346 | ||
347 | if (current->pi_state_cache) | |
348 | kfree(pi_state); | |
349 | else { | |
350 | /* | |
351 | * pi_state->list is already empty. | |
352 | * clear pi_state->owner. | |
353 | * refcount is at 0 - put it back to 1. | |
354 | */ | |
355 | pi_state->owner = NULL; | |
356 | atomic_set(&pi_state->refcount, 1); | |
357 | current->pi_state_cache = pi_state; | |
358 | } | |
359 | } | |
360 | ||
361 | /* | |
362 | * Look up the task based on what TID userspace gave us. | |
363 | * We dont trust it. | |
364 | */ | |
365 | static struct task_struct * futex_find_get_task(pid_t pid) | |
366 | { | |
367 | struct task_struct *p; | |
368 | ||
d359b549 | 369 | rcu_read_lock(); |
c87e2837 IM |
370 | p = find_task_by_pid(pid); |
371 | if (!p) | |
372 | goto out_unlock; | |
373 | if ((current->euid != p->euid) && (current->euid != p->uid)) { | |
374 | p = NULL; | |
375 | goto out_unlock; | |
376 | } | |
d015baeb | 377 | if (p->exit_state != 0) { |
c87e2837 IM |
378 | p = NULL; |
379 | goto out_unlock; | |
380 | } | |
381 | get_task_struct(p); | |
382 | out_unlock: | |
d359b549 | 383 | rcu_read_unlock(); |
c87e2837 IM |
384 | |
385 | return p; | |
386 | } | |
387 | ||
388 | /* | |
389 | * This task is holding PI mutexes at exit time => bad. | |
390 | * Kernel cleans up PI-state, but userspace is likely hosed. | |
391 | * (Robust-futex cleanup is separate and might save the day for userspace.) | |
392 | */ | |
393 | void exit_pi_state_list(struct task_struct *curr) | |
394 | { | |
c87e2837 IM |
395 | struct list_head *next, *head = &curr->pi_state_list; |
396 | struct futex_pi_state *pi_state; | |
627371d7 | 397 | struct futex_hash_bucket *hb; |
c87e2837 IM |
398 | union futex_key key; |
399 | ||
400 | /* | |
401 | * We are a ZOMBIE and nobody can enqueue itself on | |
402 | * pi_state_list anymore, but we have to be careful | |
627371d7 | 403 | * versus waiters unqueueing themselves: |
c87e2837 IM |
404 | */ |
405 | spin_lock_irq(&curr->pi_lock); | |
406 | while (!list_empty(head)) { | |
407 | ||
408 | next = head->next; | |
409 | pi_state = list_entry(next, struct futex_pi_state, list); | |
410 | key = pi_state->key; | |
627371d7 | 411 | hb = hash_futex(&key); |
c87e2837 IM |
412 | spin_unlock_irq(&curr->pi_lock); |
413 | ||
c87e2837 IM |
414 | spin_lock(&hb->lock); |
415 | ||
416 | spin_lock_irq(&curr->pi_lock); | |
627371d7 IM |
417 | /* |
418 | * We dropped the pi-lock, so re-check whether this | |
419 | * task still owns the PI-state: | |
420 | */ | |
c87e2837 IM |
421 | if (head->next != next) { |
422 | spin_unlock(&hb->lock); | |
423 | continue; | |
424 | } | |
425 | ||
c87e2837 | 426 | WARN_ON(pi_state->owner != curr); |
627371d7 IM |
427 | WARN_ON(list_empty(&pi_state->list)); |
428 | list_del_init(&pi_state->list); | |
c87e2837 IM |
429 | pi_state->owner = NULL; |
430 | spin_unlock_irq(&curr->pi_lock); | |
431 | ||
432 | rt_mutex_unlock(&pi_state->pi_mutex); | |
433 | ||
434 | spin_unlock(&hb->lock); | |
435 | ||
436 | spin_lock_irq(&curr->pi_lock); | |
437 | } | |
438 | spin_unlock_irq(&curr->pi_lock); | |
439 | } | |
440 | ||
441 | static int | |
442 | lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, struct futex_q *me) | |
443 | { | |
444 | struct futex_pi_state *pi_state = NULL; | |
445 | struct futex_q *this, *next; | |
446 | struct list_head *head; | |
447 | struct task_struct *p; | |
448 | pid_t pid; | |
449 | ||
450 | head = &hb->chain; | |
451 | ||
452 | list_for_each_entry_safe(this, next, head, list) { | |
627371d7 | 453 | if (match_futex(&this->key, &me->key)) { |
c87e2837 IM |
454 | /* |
455 | * Another waiter already exists - bump up | |
456 | * the refcount and return its pi_state: | |
457 | */ | |
458 | pi_state = this->pi_state; | |
06a9ec29 TG |
459 | /* |
460 | * Userspace might have messed up non PI and PI futexes | |
461 | */ | |
462 | if (unlikely(!pi_state)) | |
463 | return -EINVAL; | |
464 | ||
627371d7 IM |
465 | WARN_ON(!atomic_read(&pi_state->refcount)); |
466 | ||
c87e2837 IM |
467 | atomic_inc(&pi_state->refcount); |
468 | me->pi_state = pi_state; | |
469 | ||
470 | return 0; | |
471 | } | |
472 | } | |
473 | ||
474 | /* | |
e3f2ddea IM |
475 | * We are the first waiter - try to look up the real owner and attach |
476 | * the new pi_state to it, but bail out when the owner died bit is set | |
477 | * and TID = 0: | |
c87e2837 IM |
478 | */ |
479 | pid = uval & FUTEX_TID_MASK; | |
e3f2ddea IM |
480 | if (!pid && (uval & FUTEX_OWNER_DIED)) |
481 | return -ESRCH; | |
c87e2837 IM |
482 | p = futex_find_get_task(pid); |
483 | if (!p) | |
484 | return -ESRCH; | |
485 | ||
486 | pi_state = alloc_pi_state(); | |
487 | ||
488 | /* | |
489 | * Initialize the pi_mutex in locked state and make 'p' | |
490 | * the owner of it: | |
491 | */ | |
492 | rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p); | |
493 | ||
494 | /* Store the key for possible exit cleanups: */ | |
495 | pi_state->key = me->key; | |
496 | ||
497 | spin_lock_irq(&p->pi_lock); | |
627371d7 | 498 | WARN_ON(!list_empty(&pi_state->list)); |
c87e2837 IM |
499 | list_add(&pi_state->list, &p->pi_state_list); |
500 | pi_state->owner = p; | |
501 | spin_unlock_irq(&p->pi_lock); | |
502 | ||
503 | put_task_struct(p); | |
504 | ||
505 | me->pi_state = pi_state; | |
506 | ||
507 | return 0; | |
508 | } | |
509 | ||
1da177e4 LT |
510 | /* |
511 | * The hash bucket lock must be held when this is called. | |
512 | * Afterwards, the futex_q must not be accessed. | |
513 | */ | |
514 | static void wake_futex(struct futex_q *q) | |
515 | { | |
516 | list_del_init(&q->list); | |
517 | if (q->filp) | |
518 | send_sigio(&q->filp->f_owner, q->fd, POLL_IN); | |
519 | /* | |
520 | * The lock in wake_up_all() is a crucial memory barrier after the | |
521 | * list_del_init() and also before assigning to q->lock_ptr. | |
522 | */ | |
523 | wake_up_all(&q->waiters); | |
524 | /* | |
525 | * The waiting task can free the futex_q as soon as this is written, | |
526 | * without taking any locks. This must come last. | |
8e31108b AM |
527 | * |
528 | * A memory barrier is required here to prevent the following store | |
529 | * to lock_ptr from getting ahead of the wakeup. Clearing the lock | |
530 | * at the end of wake_up_all() does not prevent this store from | |
531 | * moving. | |
1da177e4 | 532 | */ |
ccdea2f8 | 533 | smp_wmb(); |
1da177e4 LT |
534 | q->lock_ptr = NULL; |
535 | } | |
536 | ||
c87e2837 IM |
537 | static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this) |
538 | { | |
539 | struct task_struct *new_owner; | |
540 | struct futex_pi_state *pi_state = this->pi_state; | |
541 | u32 curval, newval; | |
542 | ||
543 | if (!pi_state) | |
544 | return -EINVAL; | |
545 | ||
21778867 | 546 | spin_lock(&pi_state->pi_mutex.wait_lock); |
c87e2837 IM |
547 | new_owner = rt_mutex_next_owner(&pi_state->pi_mutex); |
548 | ||
549 | /* | |
550 | * This happens when we have stolen the lock and the original | |
551 | * pending owner did not enqueue itself back on the rt_mutex. | |
552 | * Thats not a tragedy. We know that way, that a lock waiter | |
553 | * is on the fly. We make the futex_q waiter the pending owner. | |
554 | */ | |
555 | if (!new_owner) | |
556 | new_owner = this->task; | |
557 | ||
558 | /* | |
559 | * We pass it to the next owner. (The WAITERS bit is always | |
560 | * kept enabled while there is PI state around. We must also | |
561 | * preserve the owner died bit.) | |
562 | */ | |
e3f2ddea IM |
563 | if (!(uval & FUTEX_OWNER_DIED)) { |
564 | newval = FUTEX_WAITERS | new_owner->pid; | |
565 | ||
a866374a | 566 | pagefault_disable(); |
e3f2ddea | 567 | curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval); |
a866374a | 568 | pagefault_enable(); |
e3f2ddea IM |
569 | if (curval == -EFAULT) |
570 | return -EFAULT; | |
571 | if (curval != uval) | |
572 | return -EINVAL; | |
573 | } | |
c87e2837 | 574 | |
627371d7 IM |
575 | spin_lock_irq(&pi_state->owner->pi_lock); |
576 | WARN_ON(list_empty(&pi_state->list)); | |
577 | list_del_init(&pi_state->list); | |
578 | spin_unlock_irq(&pi_state->owner->pi_lock); | |
579 | ||
580 | spin_lock_irq(&new_owner->pi_lock); | |
581 | WARN_ON(!list_empty(&pi_state->list)); | |
c87e2837 IM |
582 | list_add(&pi_state->list, &new_owner->pi_state_list); |
583 | pi_state->owner = new_owner; | |
627371d7 IM |
584 | spin_unlock_irq(&new_owner->pi_lock); |
585 | ||
21778867 | 586 | spin_unlock(&pi_state->pi_mutex.wait_lock); |
c87e2837 IM |
587 | rt_mutex_unlock(&pi_state->pi_mutex); |
588 | ||
589 | return 0; | |
590 | } | |
591 | ||
592 | static int unlock_futex_pi(u32 __user *uaddr, u32 uval) | |
593 | { | |
594 | u32 oldval; | |
595 | ||
596 | /* | |
597 | * There is no waiter, so we unlock the futex. The owner died | |
598 | * bit has not to be preserved here. We are the owner: | |
599 | */ | |
a866374a | 600 | pagefault_disable(); |
c87e2837 | 601 | oldval = futex_atomic_cmpxchg_inatomic(uaddr, uval, 0); |
a866374a | 602 | pagefault_enable(); |
c87e2837 IM |
603 | |
604 | if (oldval == -EFAULT) | |
605 | return oldval; | |
606 | if (oldval != uval) | |
607 | return -EAGAIN; | |
608 | ||
609 | return 0; | |
610 | } | |
611 | ||
8b8f319f IM |
612 | /* |
613 | * Express the locking dependencies for lockdep: | |
614 | */ | |
615 | static inline void | |
616 | double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) | |
617 | { | |
618 | if (hb1 <= hb2) { | |
619 | spin_lock(&hb1->lock); | |
620 | if (hb1 < hb2) | |
621 | spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); | |
622 | } else { /* hb1 > hb2 */ | |
623 | spin_lock(&hb2->lock); | |
624 | spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); | |
625 | } | |
626 | } | |
627 | ||
1da177e4 LT |
628 | /* |
629 | * Wake up all waiters hashed on the physical page that is mapped | |
630 | * to this virtual address: | |
631 | */ | |
e2970f2f | 632 | static int futex_wake(u32 __user *uaddr, int nr_wake) |
1da177e4 | 633 | { |
e2970f2f | 634 | struct futex_hash_bucket *hb; |
1da177e4 | 635 | struct futex_q *this, *next; |
e2970f2f IM |
636 | struct list_head *head; |
637 | union futex_key key; | |
1da177e4 LT |
638 | int ret; |
639 | ||
640 | down_read(¤t->mm->mmap_sem); | |
641 | ||
642 | ret = get_futex_key(uaddr, &key); | |
643 | if (unlikely(ret != 0)) | |
644 | goto out; | |
645 | ||
e2970f2f IM |
646 | hb = hash_futex(&key); |
647 | spin_lock(&hb->lock); | |
648 | head = &hb->chain; | |
1da177e4 LT |
649 | |
650 | list_for_each_entry_safe(this, next, head, list) { | |
651 | if (match_futex (&this->key, &key)) { | |
ed6f7b10 IM |
652 | if (this->pi_state) { |
653 | ret = -EINVAL; | |
654 | break; | |
655 | } | |
1da177e4 LT |
656 | wake_futex(this); |
657 | if (++ret >= nr_wake) | |
658 | break; | |
659 | } | |
660 | } | |
661 | ||
e2970f2f | 662 | spin_unlock(&hb->lock); |
1da177e4 LT |
663 | out: |
664 | up_read(¤t->mm->mmap_sem); | |
665 | return ret; | |
666 | } | |
667 | ||
4732efbe JJ |
668 | /* |
669 | * Wake up all waiters hashed on the physical page that is mapped | |
670 | * to this virtual address: | |
671 | */ | |
e2970f2f IM |
672 | static int |
673 | futex_wake_op(u32 __user *uaddr1, u32 __user *uaddr2, | |
674 | int nr_wake, int nr_wake2, int op) | |
4732efbe JJ |
675 | { |
676 | union futex_key key1, key2; | |
e2970f2f | 677 | struct futex_hash_bucket *hb1, *hb2; |
4732efbe JJ |
678 | struct list_head *head; |
679 | struct futex_q *this, *next; | |
680 | int ret, op_ret, attempt = 0; | |
681 | ||
682 | retryfull: | |
683 | down_read(¤t->mm->mmap_sem); | |
684 | ||
685 | ret = get_futex_key(uaddr1, &key1); | |
686 | if (unlikely(ret != 0)) | |
687 | goto out; | |
688 | ret = get_futex_key(uaddr2, &key2); | |
689 | if (unlikely(ret != 0)) | |
690 | goto out; | |
691 | ||
e2970f2f IM |
692 | hb1 = hash_futex(&key1); |
693 | hb2 = hash_futex(&key2); | |
4732efbe JJ |
694 | |
695 | retry: | |
8b8f319f | 696 | double_lock_hb(hb1, hb2); |
4732efbe | 697 | |
e2970f2f | 698 | op_ret = futex_atomic_op_inuser(op, uaddr2); |
4732efbe | 699 | if (unlikely(op_ret < 0)) { |
e2970f2f | 700 | u32 dummy; |
4732efbe | 701 | |
e2970f2f IM |
702 | spin_unlock(&hb1->lock); |
703 | if (hb1 != hb2) | |
704 | spin_unlock(&hb2->lock); | |
4732efbe | 705 | |
7ee1dd3f | 706 | #ifndef CONFIG_MMU |
e2970f2f IM |
707 | /* |
708 | * we don't get EFAULT from MMU faults if we don't have an MMU, | |
709 | * but we might get them from range checking | |
710 | */ | |
7ee1dd3f DH |
711 | ret = op_ret; |
712 | goto out; | |
713 | #endif | |
714 | ||
796f8d9b DG |
715 | if (unlikely(op_ret != -EFAULT)) { |
716 | ret = op_ret; | |
717 | goto out; | |
718 | } | |
719 | ||
e2970f2f IM |
720 | /* |
721 | * futex_atomic_op_inuser needs to both read and write | |
4732efbe JJ |
722 | * *(int __user *)uaddr2, but we can't modify it |
723 | * non-atomically. Therefore, if get_user below is not | |
724 | * enough, we need to handle the fault ourselves, while | |
e2970f2f IM |
725 | * still holding the mmap_sem. |
726 | */ | |
4732efbe | 727 | if (attempt++) { |
c87e2837 | 728 | if (futex_handle_fault((unsigned long)uaddr2, |
e579dcbf | 729 | attempt)) { |
730 | ret = -EFAULT; | |
4732efbe | 731 | goto out; |
e579dcbf | 732 | } |
4732efbe JJ |
733 | goto retry; |
734 | } | |
735 | ||
e2970f2f IM |
736 | /* |
737 | * If we would have faulted, release mmap_sem, | |
738 | * fault it in and start all over again. | |
739 | */ | |
4732efbe JJ |
740 | up_read(¤t->mm->mmap_sem); |
741 | ||
e2970f2f | 742 | ret = get_user(dummy, uaddr2); |
4732efbe JJ |
743 | if (ret) |
744 | return ret; | |
745 | ||
746 | goto retryfull; | |
747 | } | |
748 | ||
e2970f2f | 749 | head = &hb1->chain; |
4732efbe JJ |
750 | |
751 | list_for_each_entry_safe(this, next, head, list) { | |
752 | if (match_futex (&this->key, &key1)) { | |
753 | wake_futex(this); | |
754 | if (++ret >= nr_wake) | |
755 | break; | |
756 | } | |
757 | } | |
758 | ||
759 | if (op_ret > 0) { | |
e2970f2f | 760 | head = &hb2->chain; |
4732efbe JJ |
761 | |
762 | op_ret = 0; | |
763 | list_for_each_entry_safe(this, next, head, list) { | |
764 | if (match_futex (&this->key, &key2)) { | |
765 | wake_futex(this); | |
766 | if (++op_ret >= nr_wake2) | |
767 | break; | |
768 | } | |
769 | } | |
770 | ret += op_ret; | |
771 | } | |
772 | ||
e2970f2f IM |
773 | spin_unlock(&hb1->lock); |
774 | if (hb1 != hb2) | |
775 | spin_unlock(&hb2->lock); | |
4732efbe JJ |
776 | out: |
777 | up_read(¤t->mm->mmap_sem); | |
778 | return ret; | |
779 | } | |
780 | ||
1da177e4 LT |
781 | /* |
782 | * Requeue all waiters hashed on one physical page to another | |
783 | * physical page. | |
784 | */ | |
e2970f2f IM |
785 | static int futex_requeue(u32 __user *uaddr1, u32 __user *uaddr2, |
786 | int nr_wake, int nr_requeue, u32 *cmpval) | |
1da177e4 LT |
787 | { |
788 | union futex_key key1, key2; | |
e2970f2f | 789 | struct futex_hash_bucket *hb1, *hb2; |
1da177e4 LT |
790 | struct list_head *head1; |
791 | struct futex_q *this, *next; | |
792 | int ret, drop_count = 0; | |
793 | ||
794 | retry: | |
795 | down_read(¤t->mm->mmap_sem); | |
796 | ||
797 | ret = get_futex_key(uaddr1, &key1); | |
798 | if (unlikely(ret != 0)) | |
799 | goto out; | |
800 | ret = get_futex_key(uaddr2, &key2); | |
801 | if (unlikely(ret != 0)) | |
802 | goto out; | |
803 | ||
e2970f2f IM |
804 | hb1 = hash_futex(&key1); |
805 | hb2 = hash_futex(&key2); | |
1da177e4 | 806 | |
8b8f319f | 807 | double_lock_hb(hb1, hb2); |
1da177e4 | 808 | |
e2970f2f IM |
809 | if (likely(cmpval != NULL)) { |
810 | u32 curval; | |
1da177e4 | 811 | |
e2970f2f | 812 | ret = get_futex_value_locked(&curval, uaddr1); |
1da177e4 LT |
813 | |
814 | if (unlikely(ret)) { | |
e2970f2f IM |
815 | spin_unlock(&hb1->lock); |
816 | if (hb1 != hb2) | |
817 | spin_unlock(&hb2->lock); | |
1da177e4 | 818 | |
e2970f2f IM |
819 | /* |
820 | * If we would have faulted, release mmap_sem, fault | |
1da177e4 LT |
821 | * it in and start all over again. |
822 | */ | |
823 | up_read(¤t->mm->mmap_sem); | |
824 | ||
e2970f2f | 825 | ret = get_user(curval, uaddr1); |
1da177e4 LT |
826 | |
827 | if (!ret) | |
828 | goto retry; | |
829 | ||
830 | return ret; | |
831 | } | |
e2970f2f | 832 | if (curval != *cmpval) { |
1da177e4 LT |
833 | ret = -EAGAIN; |
834 | goto out_unlock; | |
835 | } | |
836 | } | |
837 | ||
e2970f2f | 838 | head1 = &hb1->chain; |
1da177e4 LT |
839 | list_for_each_entry_safe(this, next, head1, list) { |
840 | if (!match_futex (&this->key, &key1)) | |
841 | continue; | |
842 | if (++ret <= nr_wake) { | |
843 | wake_futex(this); | |
844 | } else { | |
59e0e0ac SD |
845 | /* |
846 | * If key1 and key2 hash to the same bucket, no need to | |
847 | * requeue. | |
848 | */ | |
849 | if (likely(head1 != &hb2->chain)) { | |
850 | list_move_tail(&this->list, &hb2->chain); | |
851 | this->lock_ptr = &hb2->lock; | |
852 | } | |
1da177e4 | 853 | this->key = key2; |
9adef58b | 854 | get_futex_key_refs(&key2); |
1da177e4 LT |
855 | drop_count++; |
856 | ||
857 | if (ret - nr_wake >= nr_requeue) | |
858 | break; | |
1da177e4 LT |
859 | } |
860 | } | |
861 | ||
862 | out_unlock: | |
e2970f2f IM |
863 | spin_unlock(&hb1->lock); |
864 | if (hb1 != hb2) | |
865 | spin_unlock(&hb2->lock); | |
1da177e4 | 866 | |
9adef58b | 867 | /* drop_futex_key_refs() must be called outside the spinlocks. */ |
1da177e4 | 868 | while (--drop_count >= 0) |
9adef58b | 869 | drop_futex_key_refs(&key1); |
1da177e4 LT |
870 | |
871 | out: | |
872 | up_read(¤t->mm->mmap_sem); | |
873 | return ret; | |
874 | } | |
875 | ||
876 | /* The key must be already stored in q->key. */ | |
877 | static inline struct futex_hash_bucket * | |
878 | queue_lock(struct futex_q *q, int fd, struct file *filp) | |
879 | { | |
e2970f2f | 880 | struct futex_hash_bucket *hb; |
1da177e4 LT |
881 | |
882 | q->fd = fd; | |
883 | q->filp = filp; | |
884 | ||
885 | init_waitqueue_head(&q->waiters); | |
886 | ||
9adef58b | 887 | get_futex_key_refs(&q->key); |
e2970f2f IM |
888 | hb = hash_futex(&q->key); |
889 | q->lock_ptr = &hb->lock; | |
1da177e4 | 890 | |
e2970f2f IM |
891 | spin_lock(&hb->lock); |
892 | return hb; | |
1da177e4 LT |
893 | } |
894 | ||
e2970f2f | 895 | static inline void __queue_me(struct futex_q *q, struct futex_hash_bucket *hb) |
1da177e4 | 896 | { |
e2970f2f | 897 | list_add_tail(&q->list, &hb->chain); |
c87e2837 | 898 | q->task = current; |
e2970f2f | 899 | spin_unlock(&hb->lock); |
1da177e4 LT |
900 | } |
901 | ||
902 | static inline void | |
e2970f2f | 903 | queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb) |
1da177e4 | 904 | { |
e2970f2f | 905 | spin_unlock(&hb->lock); |
9adef58b | 906 | drop_futex_key_refs(&q->key); |
1da177e4 LT |
907 | } |
908 | ||
909 | /* | |
910 | * queue_me and unqueue_me must be called as a pair, each | |
911 | * exactly once. They are called with the hashed spinlock held. | |
912 | */ | |
913 | ||
914 | /* The key must be already stored in q->key. */ | |
915 | static void queue_me(struct futex_q *q, int fd, struct file *filp) | |
916 | { | |
e2970f2f IM |
917 | struct futex_hash_bucket *hb; |
918 | ||
919 | hb = queue_lock(q, fd, filp); | |
920 | __queue_me(q, hb); | |
1da177e4 LT |
921 | } |
922 | ||
923 | /* Return 1 if we were still queued (ie. 0 means we were woken) */ | |
924 | static int unqueue_me(struct futex_q *q) | |
925 | { | |
1da177e4 | 926 | spinlock_t *lock_ptr; |
e2970f2f | 927 | int ret = 0; |
1da177e4 LT |
928 | |
929 | /* In the common case we don't take the spinlock, which is nice. */ | |
930 | retry: | |
931 | lock_ptr = q->lock_ptr; | |
e91467ec | 932 | barrier(); |
1da177e4 LT |
933 | if (lock_ptr != 0) { |
934 | spin_lock(lock_ptr); | |
935 | /* | |
936 | * q->lock_ptr can change between reading it and | |
937 | * spin_lock(), causing us to take the wrong lock. This | |
938 | * corrects the race condition. | |
939 | * | |
940 | * Reasoning goes like this: if we have the wrong lock, | |
941 | * q->lock_ptr must have changed (maybe several times) | |
942 | * between reading it and the spin_lock(). It can | |
943 | * change again after the spin_lock() but only if it was | |
944 | * already changed before the spin_lock(). It cannot, | |
945 | * however, change back to the original value. Therefore | |
946 | * we can detect whether we acquired the correct lock. | |
947 | */ | |
948 | if (unlikely(lock_ptr != q->lock_ptr)) { | |
949 | spin_unlock(lock_ptr); | |
950 | goto retry; | |
951 | } | |
952 | WARN_ON(list_empty(&q->list)); | |
953 | list_del(&q->list); | |
c87e2837 IM |
954 | |
955 | BUG_ON(q->pi_state); | |
956 | ||
1da177e4 LT |
957 | spin_unlock(lock_ptr); |
958 | ret = 1; | |
959 | } | |
960 | ||
9adef58b | 961 | drop_futex_key_refs(&q->key); |
1da177e4 LT |
962 | return ret; |
963 | } | |
964 | ||
c87e2837 IM |
965 | /* |
966 | * PI futexes can not be requeued and must remove themself from the | |
967 | * hash bucket. The hash bucket lock is held on entry and dropped here. | |
968 | */ | |
969 | static void unqueue_me_pi(struct futex_q *q, struct futex_hash_bucket *hb) | |
970 | { | |
971 | WARN_ON(list_empty(&q->list)); | |
972 | list_del(&q->list); | |
973 | ||
974 | BUG_ON(!q->pi_state); | |
975 | free_pi_state(q->pi_state); | |
976 | q->pi_state = NULL; | |
977 | ||
978 | spin_unlock(&hb->lock); | |
979 | ||
9adef58b | 980 | drop_futex_key_refs(&q->key); |
c87e2837 IM |
981 | } |
982 | ||
e2970f2f | 983 | static int futex_wait(u32 __user *uaddr, u32 val, unsigned long time) |
1da177e4 | 984 | { |
c87e2837 IM |
985 | struct task_struct *curr = current; |
986 | DECLARE_WAITQUEUE(wait, curr); | |
e2970f2f | 987 | struct futex_hash_bucket *hb; |
1da177e4 | 988 | struct futex_q q; |
e2970f2f IM |
989 | u32 uval; |
990 | int ret; | |
1da177e4 | 991 | |
c87e2837 | 992 | q.pi_state = NULL; |
1da177e4 | 993 | retry: |
c87e2837 | 994 | down_read(&curr->mm->mmap_sem); |
1da177e4 LT |
995 | |
996 | ret = get_futex_key(uaddr, &q.key); | |
997 | if (unlikely(ret != 0)) | |
998 | goto out_release_sem; | |
999 | ||
e2970f2f | 1000 | hb = queue_lock(&q, -1, NULL); |
1da177e4 LT |
1001 | |
1002 | /* | |
1003 | * Access the page AFTER the futex is queued. | |
1004 | * Order is important: | |
1005 | * | |
1006 | * Userspace waiter: val = var; if (cond(val)) futex_wait(&var, val); | |
1007 | * Userspace waker: if (cond(var)) { var = new; futex_wake(&var); } | |
1008 | * | |
1009 | * The basic logical guarantee of a futex is that it blocks ONLY | |
1010 | * if cond(var) is known to be true at the time of blocking, for | |
1011 | * any cond. If we queued after testing *uaddr, that would open | |
1012 | * a race condition where we could block indefinitely with | |
1013 | * cond(var) false, which would violate the guarantee. | |
1014 | * | |
1015 | * A consequence is that futex_wait() can return zero and absorb | |
1016 | * a wakeup when *uaddr != val on entry to the syscall. This is | |
1017 | * rare, but normal. | |
1018 | * | |
1019 | * We hold the mmap semaphore, so the mapping cannot have changed | |
1020 | * since we looked it up in get_futex_key. | |
1021 | */ | |
e2970f2f | 1022 | ret = get_futex_value_locked(&uval, uaddr); |
1da177e4 LT |
1023 | |
1024 | if (unlikely(ret)) { | |
e2970f2f | 1025 | queue_unlock(&q, hb); |
1da177e4 | 1026 | |
e2970f2f IM |
1027 | /* |
1028 | * If we would have faulted, release mmap_sem, fault it in and | |
1da177e4 LT |
1029 | * start all over again. |
1030 | */ | |
c87e2837 | 1031 | up_read(&curr->mm->mmap_sem); |
1da177e4 | 1032 | |
e2970f2f | 1033 | ret = get_user(uval, uaddr); |
1da177e4 LT |
1034 | |
1035 | if (!ret) | |
1036 | goto retry; | |
1037 | return ret; | |
1038 | } | |
c87e2837 IM |
1039 | ret = -EWOULDBLOCK; |
1040 | if (uval != val) | |
1041 | goto out_unlock_release_sem; | |
1da177e4 LT |
1042 | |
1043 | /* Only actually queue if *uaddr contained val. */ | |
e2970f2f | 1044 | __queue_me(&q, hb); |
1da177e4 LT |
1045 | |
1046 | /* | |
1047 | * Now the futex is queued and we have checked the data, we | |
1048 | * don't want to hold mmap_sem while we sleep. | |
c87e2837 IM |
1049 | */ |
1050 | up_read(&curr->mm->mmap_sem); | |
1da177e4 LT |
1051 | |
1052 | /* | |
1053 | * There might have been scheduling since the queue_me(), as we | |
1054 | * cannot hold a spinlock across the get_user() in case it | |
1055 | * faults, and we cannot just set TASK_INTERRUPTIBLE state when | |
1056 | * queueing ourselves into the futex hash. This code thus has to | |
1057 | * rely on the futex_wake() code removing us from hash when it | |
1058 | * wakes us up. | |
1059 | */ | |
1060 | ||
1061 | /* add_wait_queue is the barrier after __set_current_state. */ | |
1062 | __set_current_state(TASK_INTERRUPTIBLE); | |
1063 | add_wait_queue(&q.waiters, &wait); | |
1064 | /* | |
1065 | * !list_empty() is safe here without any lock. | |
1066 | * q.lock_ptr != 0 is not safe, because of ordering against wakeup. | |
1067 | */ | |
1068 | if (likely(!list_empty(&q.list))) | |
1069 | time = schedule_timeout(time); | |
1070 | __set_current_state(TASK_RUNNING); | |
1071 | ||
1072 | /* | |
1073 | * NOTE: we don't remove ourselves from the waitqueue because | |
1074 | * we are the only user of it. | |
1075 | */ | |
1076 | ||
1077 | /* If we were woken (and unqueued), we succeeded, whatever. */ | |
1078 | if (!unqueue_me(&q)) | |
1079 | return 0; | |
1080 | if (time == 0) | |
1081 | return -ETIMEDOUT; | |
e2970f2f IM |
1082 | /* |
1083 | * We expect signal_pending(current), but another thread may | |
1084 | * have handled it for us already. | |
1085 | */ | |
1da177e4 LT |
1086 | return -EINTR; |
1087 | ||
c87e2837 IM |
1088 | out_unlock_release_sem: |
1089 | queue_unlock(&q, hb); | |
1090 | ||
1da177e4 | 1091 | out_release_sem: |
c87e2837 IM |
1092 | up_read(&curr->mm->mmap_sem); |
1093 | return ret; | |
1094 | } | |
1095 | ||
1096 | /* | |
1097 | * Userspace tried a 0 -> TID atomic transition of the futex value | |
1098 | * and failed. The kernel side here does the whole locking operation: | |
1099 | * if there are waiters then it will block, it does PI, etc. (Due to | |
1100 | * races the kernel might see a 0 value of the futex too.) | |
1101 | */ | |
c5780e97 TG |
1102 | static int futex_lock_pi(u32 __user *uaddr, int detect, unsigned long sec, |
1103 | long nsec, int trylock) | |
c87e2837 | 1104 | { |
c5780e97 | 1105 | struct hrtimer_sleeper timeout, *to = NULL; |
c87e2837 IM |
1106 | struct task_struct *curr = current; |
1107 | struct futex_hash_bucket *hb; | |
1108 | u32 uval, newval, curval; | |
1109 | struct futex_q q; | |
1110 | int ret, attempt = 0; | |
1111 | ||
1112 | if (refill_pi_state_cache()) | |
1113 | return -ENOMEM; | |
1114 | ||
c5780e97 TG |
1115 | if (sec != MAX_SCHEDULE_TIMEOUT) { |
1116 | to = &timeout; | |
c9cb2e3d | 1117 | hrtimer_init(&to->timer, CLOCK_REALTIME, HRTIMER_MODE_ABS); |
c5780e97 TG |
1118 | hrtimer_init_sleeper(to, current); |
1119 | to->timer.expires = ktime_set(sec, nsec); | |
1120 | } | |
1121 | ||
c87e2837 IM |
1122 | q.pi_state = NULL; |
1123 | retry: | |
1124 | down_read(&curr->mm->mmap_sem); | |
1125 | ||
1126 | ret = get_futex_key(uaddr, &q.key); | |
1127 | if (unlikely(ret != 0)) | |
1128 | goto out_release_sem; | |
1129 | ||
1130 | hb = queue_lock(&q, -1, NULL); | |
1131 | ||
1132 | retry_locked: | |
1133 | /* | |
1134 | * To avoid races, we attempt to take the lock here again | |
1135 | * (by doing a 0 -> TID atomic cmpxchg), while holding all | |
1136 | * the locks. It will most likely not succeed. | |
1137 | */ | |
1138 | newval = current->pid; | |
1139 | ||
a866374a | 1140 | pagefault_disable(); |
c87e2837 | 1141 | curval = futex_atomic_cmpxchg_inatomic(uaddr, 0, newval); |
a866374a | 1142 | pagefault_enable(); |
c87e2837 IM |
1143 | |
1144 | if (unlikely(curval == -EFAULT)) | |
1145 | goto uaddr_faulted; | |
1146 | ||
1147 | /* We own the lock already */ | |
1148 | if (unlikely((curval & FUTEX_TID_MASK) == current->pid)) { | |
1149 | if (!detect && 0) | |
1150 | force_sig(SIGKILL, current); | |
1151 | ret = -EDEADLK; | |
1152 | goto out_unlock_release_sem; | |
1153 | } | |
1154 | ||
1155 | /* | |
1156 | * Surprise - we got the lock. Just return | |
1157 | * to userspace: | |
1158 | */ | |
1159 | if (unlikely(!curval)) | |
1160 | goto out_unlock_release_sem; | |
1161 | ||
1162 | uval = curval; | |
1163 | newval = uval | FUTEX_WAITERS; | |
1164 | ||
a866374a | 1165 | pagefault_disable(); |
c87e2837 | 1166 | curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval); |
a866374a | 1167 | pagefault_enable(); |
c87e2837 IM |
1168 | |
1169 | if (unlikely(curval == -EFAULT)) | |
1170 | goto uaddr_faulted; | |
1171 | if (unlikely(curval != uval)) | |
1172 | goto retry_locked; | |
1173 | ||
1174 | /* | |
1175 | * We dont have the lock. Look up the PI state (or create it if | |
1176 | * we are the first waiter): | |
1177 | */ | |
1178 | ret = lookup_pi_state(uval, hb, &q); | |
1179 | ||
1180 | if (unlikely(ret)) { | |
1181 | /* | |
1182 | * There were no waiters and the owner task lookup | |
1183 | * failed. When the OWNER_DIED bit is set, then we | |
1184 | * know that this is a robust futex and we actually | |
1185 | * take the lock. This is safe as we are protected by | |
1186 | * the hash bucket lock. We also set the waiters bit | |
1187 | * unconditionally here, to simplify glibc handling of | |
1188 | * multiple tasks racing to acquire the lock and | |
1189 | * cleanup the problems which were left by the dead | |
1190 | * owner. | |
1191 | */ | |
1192 | if (curval & FUTEX_OWNER_DIED) { | |
1193 | uval = newval; | |
1194 | newval = current->pid | | |
1195 | FUTEX_OWNER_DIED | FUTEX_WAITERS; | |
1196 | ||
a866374a | 1197 | pagefault_disable(); |
c87e2837 IM |
1198 | curval = futex_atomic_cmpxchg_inatomic(uaddr, |
1199 | uval, newval); | |
a866374a | 1200 | pagefault_enable(); |
c87e2837 IM |
1201 | |
1202 | if (unlikely(curval == -EFAULT)) | |
1203 | goto uaddr_faulted; | |
1204 | if (unlikely(curval != uval)) | |
1205 | goto retry_locked; | |
1206 | ret = 0; | |
1207 | } | |
1208 | goto out_unlock_release_sem; | |
1209 | } | |
1210 | ||
1211 | /* | |
1212 | * Only actually queue now that the atomic ops are done: | |
1213 | */ | |
1214 | __queue_me(&q, hb); | |
1215 | ||
1216 | /* | |
1217 | * Now the futex is queued and we have checked the data, we | |
1218 | * don't want to hold mmap_sem while we sleep. | |
1219 | */ | |
1220 | up_read(&curr->mm->mmap_sem); | |
1221 | ||
1222 | WARN_ON(!q.pi_state); | |
1223 | /* | |
1224 | * Block on the PI mutex: | |
1225 | */ | |
1226 | if (!trylock) | |
1227 | ret = rt_mutex_timed_lock(&q.pi_state->pi_mutex, to, 1); | |
1228 | else { | |
1229 | ret = rt_mutex_trylock(&q.pi_state->pi_mutex); | |
1230 | /* Fixup the trylock return value: */ | |
1231 | ret = ret ? 0 : -EWOULDBLOCK; | |
1232 | } | |
1233 | ||
1234 | down_read(&curr->mm->mmap_sem); | |
a99e4e41 | 1235 | spin_lock(q.lock_ptr); |
c87e2837 IM |
1236 | |
1237 | /* | |
1238 | * Got the lock. We might not be the anticipated owner if we | |
1239 | * did a lock-steal - fix up the PI-state in that case. | |
1240 | */ | |
1241 | if (!ret && q.pi_state->owner != curr) { | |
1242 | u32 newtid = current->pid | FUTEX_WAITERS; | |
1243 | ||
1244 | /* Owner died? */ | |
1245 | if (q.pi_state->owner != NULL) { | |
1246 | spin_lock_irq(&q.pi_state->owner->pi_lock); | |
627371d7 | 1247 | WARN_ON(list_empty(&q.pi_state->list)); |
c87e2837 IM |
1248 | list_del_init(&q.pi_state->list); |
1249 | spin_unlock_irq(&q.pi_state->owner->pi_lock); | |
1250 | } else | |
1251 | newtid |= FUTEX_OWNER_DIED; | |
1252 | ||
1253 | q.pi_state->owner = current; | |
1254 | ||
1255 | spin_lock_irq(¤t->pi_lock); | |
627371d7 | 1256 | WARN_ON(!list_empty(&q.pi_state->list)); |
c87e2837 IM |
1257 | list_add(&q.pi_state->list, ¤t->pi_state_list); |
1258 | spin_unlock_irq(¤t->pi_lock); | |
1259 | ||
1260 | /* Unqueue and drop the lock */ | |
1261 | unqueue_me_pi(&q, hb); | |
1262 | up_read(&curr->mm->mmap_sem); | |
1263 | /* | |
1264 | * We own it, so we have to replace the pending owner | |
1265 | * TID. This must be atomic as we have preserve the | |
1266 | * owner died bit here. | |
1267 | */ | |
1268 | ret = get_user(uval, uaddr); | |
1269 | while (!ret) { | |
1270 | newval = (uval & FUTEX_OWNER_DIED) | newtid; | |
1271 | curval = futex_atomic_cmpxchg_inatomic(uaddr, | |
1272 | uval, newval); | |
1273 | if (curval == -EFAULT) | |
1274 | ret = -EFAULT; | |
1275 | if (curval == uval) | |
1276 | break; | |
1277 | uval = curval; | |
1278 | } | |
1279 | } else { | |
1280 | /* | |
1281 | * Catch the rare case, where the lock was released | |
1282 | * when we were on the way back before we locked | |
1283 | * the hash bucket. | |
1284 | */ | |
1285 | if (ret && q.pi_state->owner == curr) { | |
1286 | if (rt_mutex_trylock(&q.pi_state->pi_mutex)) | |
1287 | ret = 0; | |
1288 | } | |
1289 | /* Unqueue and drop the lock */ | |
1290 | unqueue_me_pi(&q, hb); | |
1291 | up_read(&curr->mm->mmap_sem); | |
1292 | } | |
1293 | ||
1294 | if (!detect && ret == -EDEADLK && 0) | |
1295 | force_sig(SIGKILL, current); | |
1296 | ||
c5780e97 | 1297 | return ret != -EINTR ? ret : -ERESTARTNOINTR; |
c87e2837 IM |
1298 | |
1299 | out_unlock_release_sem: | |
1300 | queue_unlock(&q, hb); | |
1301 | ||
1302 | out_release_sem: | |
1303 | up_read(&curr->mm->mmap_sem); | |
1304 | return ret; | |
1305 | ||
1306 | uaddr_faulted: | |
1307 | /* | |
1308 | * We have to r/w *(int __user *)uaddr, but we can't modify it | |
1309 | * non-atomically. Therefore, if get_user below is not | |
1310 | * enough, we need to handle the fault ourselves, while | |
1311 | * still holding the mmap_sem. | |
1312 | */ | |
1313 | if (attempt++) { | |
e579dcbf | 1314 | if (futex_handle_fault((unsigned long)uaddr, attempt)) { |
1315 | ret = -EFAULT; | |
c87e2837 | 1316 | goto out_unlock_release_sem; |
e579dcbf | 1317 | } |
c87e2837 IM |
1318 | goto retry_locked; |
1319 | } | |
1320 | ||
1321 | queue_unlock(&q, hb); | |
1322 | up_read(&curr->mm->mmap_sem); | |
1323 | ||
1324 | ret = get_user(uval, uaddr); | |
1325 | if (!ret && (uval != -EFAULT)) | |
1326 | goto retry; | |
1327 | ||
1328 | return ret; | |
1329 | } | |
1330 | ||
c87e2837 IM |
1331 | /* |
1332 | * Userspace attempted a TID -> 0 atomic transition, and failed. | |
1333 | * This is the in-kernel slowpath: we look up the PI state (if any), | |
1334 | * and do the rt-mutex unlock. | |
1335 | */ | |
1336 | static int futex_unlock_pi(u32 __user *uaddr) | |
1337 | { | |
1338 | struct futex_hash_bucket *hb; | |
1339 | struct futex_q *this, *next; | |
1340 | u32 uval; | |
1341 | struct list_head *head; | |
1342 | union futex_key key; | |
1343 | int ret, attempt = 0; | |
1344 | ||
1345 | retry: | |
1346 | if (get_user(uval, uaddr)) | |
1347 | return -EFAULT; | |
1348 | /* | |
1349 | * We release only a lock we actually own: | |
1350 | */ | |
1351 | if ((uval & FUTEX_TID_MASK) != current->pid) | |
1352 | return -EPERM; | |
1353 | /* | |
1354 | * First take all the futex related locks: | |
1355 | */ | |
1356 | down_read(¤t->mm->mmap_sem); | |
1357 | ||
1358 | ret = get_futex_key(uaddr, &key); | |
1359 | if (unlikely(ret != 0)) | |
1360 | goto out; | |
1361 | ||
1362 | hb = hash_futex(&key); | |
1363 | spin_lock(&hb->lock); | |
1364 | ||
1365 | retry_locked: | |
1366 | /* | |
1367 | * To avoid races, try to do the TID -> 0 atomic transition | |
1368 | * again. If it succeeds then we can return without waking | |
1369 | * anyone else up: | |
1370 | */ | |
e3f2ddea | 1371 | if (!(uval & FUTEX_OWNER_DIED)) { |
a866374a | 1372 | pagefault_disable(); |
e3f2ddea | 1373 | uval = futex_atomic_cmpxchg_inatomic(uaddr, current->pid, 0); |
a866374a | 1374 | pagefault_enable(); |
e3f2ddea | 1375 | } |
c87e2837 IM |
1376 | |
1377 | if (unlikely(uval == -EFAULT)) | |
1378 | goto pi_faulted; | |
1379 | /* | |
1380 | * Rare case: we managed to release the lock atomically, | |
1381 | * no need to wake anyone else up: | |
1382 | */ | |
1383 | if (unlikely(uval == current->pid)) | |
1384 | goto out_unlock; | |
1385 | ||
1386 | /* | |
1387 | * Ok, other tasks may need to be woken up - check waiters | |
1388 | * and do the wakeup if necessary: | |
1389 | */ | |
1390 | head = &hb->chain; | |
1391 | ||
1392 | list_for_each_entry_safe(this, next, head, list) { | |
1393 | if (!match_futex (&this->key, &key)) | |
1394 | continue; | |
1395 | ret = wake_futex_pi(uaddr, uval, this); | |
1396 | /* | |
1397 | * The atomic access to the futex value | |
1398 | * generated a pagefault, so retry the | |
1399 | * user-access and the wakeup: | |
1400 | */ | |
1401 | if (ret == -EFAULT) | |
1402 | goto pi_faulted; | |
1403 | goto out_unlock; | |
1404 | } | |
1405 | /* | |
1406 | * No waiters - kernel unlocks the futex: | |
1407 | */ | |
e3f2ddea IM |
1408 | if (!(uval & FUTEX_OWNER_DIED)) { |
1409 | ret = unlock_futex_pi(uaddr, uval); | |
1410 | if (ret == -EFAULT) | |
1411 | goto pi_faulted; | |
1412 | } | |
c87e2837 IM |
1413 | |
1414 | out_unlock: | |
1415 | spin_unlock(&hb->lock); | |
1416 | out: | |
1417 | up_read(¤t->mm->mmap_sem); | |
1418 | ||
1419 | return ret; | |
1420 | ||
1421 | pi_faulted: | |
1422 | /* | |
1423 | * We have to r/w *(int __user *)uaddr, but we can't modify it | |
1424 | * non-atomically. Therefore, if get_user below is not | |
1425 | * enough, we need to handle the fault ourselves, while | |
1426 | * still holding the mmap_sem. | |
1427 | */ | |
1428 | if (attempt++) { | |
e579dcbf | 1429 | if (futex_handle_fault((unsigned long)uaddr, attempt)) { |
1430 | ret = -EFAULT; | |
c87e2837 | 1431 | goto out_unlock; |
e579dcbf | 1432 | } |
c87e2837 IM |
1433 | goto retry_locked; |
1434 | } | |
1435 | ||
1436 | spin_unlock(&hb->lock); | |
1da177e4 | 1437 | up_read(¤t->mm->mmap_sem); |
c87e2837 IM |
1438 | |
1439 | ret = get_user(uval, uaddr); | |
1440 | if (!ret && (uval != -EFAULT)) | |
1441 | goto retry; | |
1442 | ||
1da177e4 LT |
1443 | return ret; |
1444 | } | |
1445 | ||
1446 | static int futex_close(struct inode *inode, struct file *filp) | |
1447 | { | |
1448 | struct futex_q *q = filp->private_data; | |
1449 | ||
1450 | unqueue_me(q); | |
1451 | kfree(q); | |
e2970f2f | 1452 | |
1da177e4 LT |
1453 | return 0; |
1454 | } | |
1455 | ||
1456 | /* This is one-shot: once it's gone off you need a new fd */ | |
1457 | static unsigned int futex_poll(struct file *filp, | |
1458 | struct poll_table_struct *wait) | |
1459 | { | |
1460 | struct futex_q *q = filp->private_data; | |
1461 | int ret = 0; | |
1462 | ||
1463 | poll_wait(filp, &q->waiters, wait); | |
1464 | ||
1465 | /* | |
1466 | * list_empty() is safe here without any lock. | |
1467 | * q->lock_ptr != 0 is not safe, because of ordering against wakeup. | |
1468 | */ | |
1469 | if (list_empty(&q->list)) | |
1470 | ret = POLLIN | POLLRDNORM; | |
1471 | ||
1472 | return ret; | |
1473 | } | |
1474 | ||
15ad7cdc | 1475 | static const struct file_operations futex_fops = { |
1da177e4 LT |
1476 | .release = futex_close, |
1477 | .poll = futex_poll, | |
1478 | }; | |
1479 | ||
1480 | /* | |
1481 | * Signal allows caller to avoid the race which would occur if they | |
1482 | * set the sigio stuff up afterwards. | |
1483 | */ | |
e2970f2f | 1484 | static int futex_fd(u32 __user *uaddr, int signal) |
1da177e4 LT |
1485 | { |
1486 | struct futex_q *q; | |
1487 | struct file *filp; | |
1488 | int ret, err; | |
19c6b6ed AM |
1489 | static unsigned long printk_interval; |
1490 | ||
1491 | if (printk_timed_ratelimit(&printk_interval, 60 * 60 * 1000)) { | |
1492 | printk(KERN_WARNING "Process `%s' used FUTEX_FD, which " | |
1493 | "will be removed from the kernel in June 2007\n", | |
1494 | current->comm); | |
1495 | } | |
1da177e4 LT |
1496 | |
1497 | ret = -EINVAL; | |
7ed20e1a | 1498 | if (!valid_signal(signal)) |
1da177e4 LT |
1499 | goto out; |
1500 | ||
1501 | ret = get_unused_fd(); | |
1502 | if (ret < 0) | |
1503 | goto out; | |
1504 | filp = get_empty_filp(); | |
1505 | if (!filp) { | |
1506 | put_unused_fd(ret); | |
1507 | ret = -ENFILE; | |
1508 | goto out; | |
1509 | } | |
1510 | filp->f_op = &futex_fops; | |
f3a43f3f JJS |
1511 | filp->f_path.mnt = mntget(futex_mnt); |
1512 | filp->f_path.dentry = dget(futex_mnt->mnt_root); | |
1513 | filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping; | |
1da177e4 LT |
1514 | |
1515 | if (signal) { | |
609d7fa9 | 1516 | err = __f_setown(filp, task_pid(current), PIDTYPE_PID, 1); |
1da177e4 | 1517 | if (err < 0) { |
39ed3fde | 1518 | goto error; |
1da177e4 LT |
1519 | } |
1520 | filp->f_owner.signum = signal; | |
1521 | } | |
1522 | ||
1523 | q = kmalloc(sizeof(*q), GFP_KERNEL); | |
1524 | if (!q) { | |
39ed3fde PE |
1525 | err = -ENOMEM; |
1526 | goto error; | |
1da177e4 | 1527 | } |
c87e2837 | 1528 | q->pi_state = NULL; |
1da177e4 LT |
1529 | |
1530 | down_read(¤t->mm->mmap_sem); | |
1531 | err = get_futex_key(uaddr, &q->key); | |
1532 | ||
1533 | if (unlikely(err != 0)) { | |
1534 | up_read(¤t->mm->mmap_sem); | |
1da177e4 | 1535 | kfree(q); |
39ed3fde | 1536 | goto error; |
1da177e4 LT |
1537 | } |
1538 | ||
1539 | /* | |
1540 | * queue_me() must be called before releasing mmap_sem, because | |
1541 | * key->shared.inode needs to be referenced while holding it. | |
1542 | */ | |
1543 | filp->private_data = q; | |
1544 | ||
1545 | queue_me(q, ret, filp); | |
1546 | up_read(¤t->mm->mmap_sem); | |
1547 | ||
1548 | /* Now we map fd to filp, so userspace can access it */ | |
1549 | fd_install(ret, filp); | |
1550 | out: | |
1551 | return ret; | |
39ed3fde PE |
1552 | error: |
1553 | put_unused_fd(ret); | |
1554 | put_filp(filp); | |
1555 | ret = err; | |
1556 | goto out; | |
1da177e4 LT |
1557 | } |
1558 | ||
0771dfef IM |
1559 | /* |
1560 | * Support for robust futexes: the kernel cleans up held futexes at | |
1561 | * thread exit time. | |
1562 | * | |
1563 | * Implementation: user-space maintains a per-thread list of locks it | |
1564 | * is holding. Upon do_exit(), the kernel carefully walks this list, | |
1565 | * and marks all locks that are owned by this thread with the | |
c87e2837 | 1566 | * FUTEX_OWNER_DIED bit, and wakes up a waiter (if any). The list is |
0771dfef IM |
1567 | * always manipulated with the lock held, so the list is private and |
1568 | * per-thread. Userspace also maintains a per-thread 'list_op_pending' | |
1569 | * field, to allow the kernel to clean up if the thread dies after | |
1570 | * acquiring the lock, but just before it could have added itself to | |
1571 | * the list. There can only be one such pending lock. | |
1572 | */ | |
1573 | ||
1574 | /** | |
1575 | * sys_set_robust_list - set the robust-futex list head of a task | |
1576 | * @head: pointer to the list-head | |
1577 | * @len: length of the list-head, as userspace expects | |
1578 | */ | |
1579 | asmlinkage long | |
1580 | sys_set_robust_list(struct robust_list_head __user *head, | |
1581 | size_t len) | |
1582 | { | |
1583 | /* | |
1584 | * The kernel knows only one size for now: | |
1585 | */ | |
1586 | if (unlikely(len != sizeof(*head))) | |
1587 | return -EINVAL; | |
1588 | ||
1589 | current->robust_list = head; | |
1590 | ||
1591 | return 0; | |
1592 | } | |
1593 | ||
1594 | /** | |
1595 | * sys_get_robust_list - get the robust-futex list head of a task | |
1596 | * @pid: pid of the process [zero for current task] | |
1597 | * @head_ptr: pointer to a list-head pointer, the kernel fills it in | |
1598 | * @len_ptr: pointer to a length field, the kernel fills in the header size | |
1599 | */ | |
1600 | asmlinkage long | |
ba46df98 | 1601 | sys_get_robust_list(int pid, struct robust_list_head __user * __user *head_ptr, |
0771dfef IM |
1602 | size_t __user *len_ptr) |
1603 | { | |
ba46df98 | 1604 | struct robust_list_head __user *head; |
0771dfef IM |
1605 | unsigned long ret; |
1606 | ||
1607 | if (!pid) | |
1608 | head = current->robust_list; | |
1609 | else { | |
1610 | struct task_struct *p; | |
1611 | ||
1612 | ret = -ESRCH; | |
aaa2a97e | 1613 | rcu_read_lock(); |
0771dfef IM |
1614 | p = find_task_by_pid(pid); |
1615 | if (!p) | |
1616 | goto err_unlock; | |
1617 | ret = -EPERM; | |
1618 | if ((current->euid != p->euid) && (current->euid != p->uid) && | |
1619 | !capable(CAP_SYS_PTRACE)) | |
1620 | goto err_unlock; | |
1621 | head = p->robust_list; | |
aaa2a97e | 1622 | rcu_read_unlock(); |
0771dfef IM |
1623 | } |
1624 | ||
1625 | if (put_user(sizeof(*head), len_ptr)) | |
1626 | return -EFAULT; | |
1627 | return put_user(head, head_ptr); | |
1628 | ||
1629 | err_unlock: | |
aaa2a97e | 1630 | rcu_read_unlock(); |
0771dfef IM |
1631 | |
1632 | return ret; | |
1633 | } | |
1634 | ||
1635 | /* | |
1636 | * Process a futex-list entry, check whether it's owned by the | |
1637 | * dying task, and do notification if so: | |
1638 | */ | |
e3f2ddea | 1639 | int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi) |
0771dfef | 1640 | { |
e3f2ddea | 1641 | u32 uval, nval, mval; |
0771dfef | 1642 | |
8f17d3a5 IM |
1643 | retry: |
1644 | if (get_user(uval, uaddr)) | |
0771dfef IM |
1645 | return -1; |
1646 | ||
8f17d3a5 | 1647 | if ((uval & FUTEX_TID_MASK) == curr->pid) { |
0771dfef IM |
1648 | /* |
1649 | * Ok, this dying thread is truly holding a futex | |
1650 | * of interest. Set the OWNER_DIED bit atomically | |
1651 | * via cmpxchg, and if the value had FUTEX_WAITERS | |
1652 | * set, wake up a waiter (if any). (We have to do a | |
1653 | * futex_wake() even if OWNER_DIED is already set - | |
1654 | * to handle the rare but possible case of recursive | |
1655 | * thread-death.) The rest of the cleanup is done in | |
1656 | * userspace. | |
1657 | */ | |
e3f2ddea IM |
1658 | mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; |
1659 | nval = futex_atomic_cmpxchg_inatomic(uaddr, uval, mval); | |
1660 | ||
c87e2837 IM |
1661 | if (nval == -EFAULT) |
1662 | return -1; | |
1663 | ||
1664 | if (nval != uval) | |
8f17d3a5 | 1665 | goto retry; |
0771dfef | 1666 | |
e3f2ddea IM |
1667 | /* |
1668 | * Wake robust non-PI futexes here. The wakeup of | |
1669 | * PI futexes happens in exit_pi_state(): | |
1670 | */ | |
1671 | if (!pi) { | |
1672 | if (uval & FUTEX_WAITERS) | |
1673 | futex_wake(uaddr, 1); | |
1674 | } | |
0771dfef IM |
1675 | } |
1676 | return 0; | |
1677 | } | |
1678 | ||
e3f2ddea IM |
1679 | /* |
1680 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: | |
1681 | */ | |
1682 | static inline int fetch_robust_entry(struct robust_list __user **entry, | |
ba46df98 AV |
1683 | struct robust_list __user * __user *head, |
1684 | int *pi) | |
e3f2ddea IM |
1685 | { |
1686 | unsigned long uentry; | |
1687 | ||
ba46df98 | 1688 | if (get_user(uentry, (unsigned long __user *)head)) |
e3f2ddea IM |
1689 | return -EFAULT; |
1690 | ||
ba46df98 | 1691 | *entry = (void __user *)(uentry & ~1UL); |
e3f2ddea IM |
1692 | *pi = uentry & 1; |
1693 | ||
1694 | return 0; | |
1695 | } | |
1696 | ||
0771dfef IM |
1697 | /* |
1698 | * Walk curr->robust_list (very carefully, it's a userspace list!) | |
1699 | * and mark any locks found there dead, and notify any waiters. | |
1700 | * | |
1701 | * We silently return on any sign of list-walking problem. | |
1702 | */ | |
1703 | void exit_robust_list(struct task_struct *curr) | |
1704 | { | |
1705 | struct robust_list_head __user *head = curr->robust_list; | |
1706 | struct robust_list __user *entry, *pending; | |
e3f2ddea | 1707 | unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; |
0771dfef IM |
1708 | unsigned long futex_offset; |
1709 | ||
1710 | /* | |
1711 | * Fetch the list head (which was registered earlier, via | |
1712 | * sys_set_robust_list()): | |
1713 | */ | |
e3f2ddea | 1714 | if (fetch_robust_entry(&entry, &head->list.next, &pi)) |
0771dfef IM |
1715 | return; |
1716 | /* | |
1717 | * Fetch the relative futex offset: | |
1718 | */ | |
1719 | if (get_user(futex_offset, &head->futex_offset)) | |
1720 | return; | |
1721 | /* | |
1722 | * Fetch any possibly pending lock-add first, and handle it | |
1723 | * if it exists: | |
1724 | */ | |
e3f2ddea | 1725 | if (fetch_robust_entry(&pending, &head->list_op_pending, &pip)) |
0771dfef | 1726 | return; |
e3f2ddea | 1727 | |
0771dfef | 1728 | if (pending) |
ba46df98 | 1729 | handle_futex_death((void __user *)pending + futex_offset, curr, pip); |
0771dfef IM |
1730 | |
1731 | while (entry != &head->list) { | |
1732 | /* | |
1733 | * A pending lock might already be on the list, so | |
c87e2837 | 1734 | * don't process it twice: |
0771dfef IM |
1735 | */ |
1736 | if (entry != pending) | |
ba46df98 | 1737 | if (handle_futex_death((void __user *)entry + futex_offset, |
e3f2ddea | 1738 | curr, pi)) |
0771dfef | 1739 | return; |
0771dfef IM |
1740 | /* |
1741 | * Fetch the next entry in the list: | |
1742 | */ | |
e3f2ddea | 1743 | if (fetch_robust_entry(&entry, &entry->next, &pi)) |
0771dfef IM |
1744 | return; |
1745 | /* | |
1746 | * Avoid excessively long or circular lists: | |
1747 | */ | |
1748 | if (!--limit) | |
1749 | break; | |
1750 | ||
1751 | cond_resched(); | |
1752 | } | |
1753 | } | |
1754 | ||
e2970f2f IM |
1755 | long do_futex(u32 __user *uaddr, int op, u32 val, unsigned long timeout, |
1756 | u32 __user *uaddr2, u32 val2, u32 val3) | |
1da177e4 LT |
1757 | { |
1758 | int ret; | |
1759 | ||
1760 | switch (op) { | |
1761 | case FUTEX_WAIT: | |
1762 | ret = futex_wait(uaddr, val, timeout); | |
1763 | break; | |
1764 | case FUTEX_WAKE: | |
1765 | ret = futex_wake(uaddr, val); | |
1766 | break; | |
1767 | case FUTEX_FD: | |
1768 | /* non-zero val means F_SETOWN(getpid()) & F_SETSIG(val) */ | |
1769 | ret = futex_fd(uaddr, val); | |
1770 | break; | |
1771 | case FUTEX_REQUEUE: | |
1772 | ret = futex_requeue(uaddr, uaddr2, val, val2, NULL); | |
1773 | break; | |
1774 | case FUTEX_CMP_REQUEUE: | |
1775 | ret = futex_requeue(uaddr, uaddr2, val, val2, &val3); | |
1776 | break; | |
4732efbe JJ |
1777 | case FUTEX_WAKE_OP: |
1778 | ret = futex_wake_op(uaddr, uaddr2, val, val2, val3); | |
1779 | break; | |
c87e2837 IM |
1780 | case FUTEX_LOCK_PI: |
1781 | ret = futex_lock_pi(uaddr, val, timeout, val2, 0); | |
1782 | break; | |
1783 | case FUTEX_UNLOCK_PI: | |
1784 | ret = futex_unlock_pi(uaddr); | |
1785 | break; | |
1786 | case FUTEX_TRYLOCK_PI: | |
1787 | ret = futex_lock_pi(uaddr, 0, timeout, val2, 1); | |
1788 | break; | |
1da177e4 LT |
1789 | default: |
1790 | ret = -ENOSYS; | |
1791 | } | |
1792 | return ret; | |
1793 | } | |
1794 | ||
1795 | ||
e2970f2f | 1796 | asmlinkage long sys_futex(u32 __user *uaddr, int op, u32 val, |
1da177e4 | 1797 | struct timespec __user *utime, u32 __user *uaddr2, |
e2970f2f | 1798 | u32 val3) |
1da177e4 LT |
1799 | { |
1800 | struct timespec t; | |
1801 | unsigned long timeout = MAX_SCHEDULE_TIMEOUT; | |
e2970f2f | 1802 | u32 val2 = 0; |
1da177e4 | 1803 | |
c87e2837 | 1804 | if (utime && (op == FUTEX_WAIT || op == FUTEX_LOCK_PI)) { |
1da177e4 LT |
1805 | if (copy_from_user(&t, utime, sizeof(t)) != 0) |
1806 | return -EFAULT; | |
9741ef96 TG |
1807 | if (!timespec_valid(&t)) |
1808 | return -EINVAL; | |
c87e2837 IM |
1809 | if (op == FUTEX_WAIT) |
1810 | timeout = timespec_to_jiffies(&t) + 1; | |
1811 | else { | |
1812 | timeout = t.tv_sec; | |
1813 | val2 = t.tv_nsec; | |
1814 | } | |
1da177e4 LT |
1815 | } |
1816 | /* | |
1817 | * requeue parameter in 'utime' if op == FUTEX_REQUEUE. | |
1818 | */ | |
c87e2837 | 1819 | if (op == FUTEX_REQUEUE || op == FUTEX_CMP_REQUEUE) |
e2970f2f | 1820 | val2 = (u32) (unsigned long) utime; |
1da177e4 | 1821 | |
e2970f2f | 1822 | return do_futex(uaddr, op, val, timeout, uaddr2, val2, val3); |
1da177e4 LT |
1823 | } |
1824 | ||
454e2398 DH |
1825 | static int futexfs_get_sb(struct file_system_type *fs_type, |
1826 | int flags, const char *dev_name, void *data, | |
1827 | struct vfsmount *mnt) | |
1da177e4 | 1828 | { |
454e2398 | 1829 | return get_sb_pseudo(fs_type, "futex", NULL, 0xBAD1DEA, mnt); |
1da177e4 LT |
1830 | } |
1831 | ||
1832 | static struct file_system_type futex_fs_type = { | |
1833 | .name = "futexfs", | |
1834 | .get_sb = futexfs_get_sb, | |
1835 | .kill_sb = kill_anon_super, | |
1836 | }; | |
1837 | ||
1838 | static int __init init(void) | |
1839 | { | |
95362fa9 AM |
1840 | int i = register_filesystem(&futex_fs_type); |
1841 | ||
1842 | if (i) | |
1843 | return i; | |
1da177e4 | 1844 | |
1da177e4 | 1845 | futex_mnt = kern_mount(&futex_fs_type); |
95362fa9 AM |
1846 | if (IS_ERR(futex_mnt)) { |
1847 | unregister_filesystem(&futex_fs_type); | |
1848 | return PTR_ERR(futex_mnt); | |
1849 | } | |
1da177e4 LT |
1850 | |
1851 | for (i = 0; i < ARRAY_SIZE(futex_queues); i++) { | |
1852 | INIT_LIST_HEAD(&futex_queues[i].chain); | |
1853 | spin_lock_init(&futex_queues[i].lock); | |
1854 | } | |
1855 | return 0; | |
1856 | } | |
1857 | __initcall(init); |