Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | * |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 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 | * |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 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 | * |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 19 | * PRIVATE futexes by Eric Dumazet |
| 20 | * Copyright (C) 2007 Eric Dumazet <dada1@cosmosbay.com> |
| 21 | * |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 22 | * Requeue-PI support by Darren Hart <dvhltc@us.ibm.com> |
| 23 | * Copyright (C) IBM Corporation, 2009 |
| 24 | * Thanks to Thomas Gleixner for conceptual design and careful reviews. |
| 25 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 26 | * Thanks to Ben LaHaise for yelling "hashed waitqueues" loudly |
| 27 | * enough at me, Linus for the original (flawed) idea, Matthew |
| 28 | * Kirkwood for proof-of-concept implementation. |
| 29 | * |
| 30 | * "The futexes are also cursed." |
| 31 | * "But they come in a choice of three flavours!" |
| 32 | * |
| 33 | * This program is free software; you can redistribute it and/or modify |
| 34 | * it under the terms of the GNU General Public License as published by |
| 35 | * the Free Software Foundation; either version 2 of the License, or |
| 36 | * (at your option) any later version. |
| 37 | * |
| 38 | * This program is distributed in the hope that it will be useful, |
| 39 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 40 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 41 | * GNU General Public License for more details. |
| 42 | * |
| 43 | * You should have received a copy of the GNU General Public License |
| 44 | * along with this program; if not, write to the Free Software |
| 45 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 46 | */ |
| 47 | #include <linux/slab.h> |
| 48 | #include <linux/poll.h> |
| 49 | #include <linux/fs.h> |
| 50 | #include <linux/file.h> |
| 51 | #include <linux/jhash.h> |
| 52 | #include <linux/init.h> |
| 53 | #include <linux/futex.h> |
| 54 | #include <linux/mount.h> |
| 55 | #include <linux/pagemap.h> |
| 56 | #include <linux/syscalls.h> |
Jesper Juhl | 7ed20e1 | 2005-05-01 08:59:14 -0700 | [diff] [blame] | 57 | #include <linux/signal.h> |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 58 | #include <linux/module.h> |
Andrey Mirkin | fd5eea4 | 2007-10-16 23:30:13 -0700 | [diff] [blame] | 59 | #include <linux/magic.h> |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 60 | #include <linux/pid.h> |
| 61 | #include <linux/nsproxy.h> |
| 62 | |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 63 | #include <asm/futex.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 65 | #include "rtmutex_common.h" |
| 66 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 67 | int __read_mostly futex_cmpxchg_enabled; |
| 68 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | #define FUTEX_HASHBITS (CONFIG_BASE_SMALL ? 4 : 8) |
| 70 | |
| 71 | /* |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 72 | * Priority Inheritance state: |
| 73 | */ |
| 74 | struct futex_pi_state { |
| 75 | /* |
| 76 | * list of 'owned' pi_state instances - these have to be |
| 77 | * cleaned up in do_exit() if the task exits prematurely: |
| 78 | */ |
| 79 | struct list_head list; |
| 80 | |
| 81 | /* |
| 82 | * The PI object: |
| 83 | */ |
| 84 | struct rt_mutex pi_mutex; |
| 85 | |
| 86 | struct task_struct *owner; |
| 87 | atomic_t refcount; |
| 88 | |
| 89 | union futex_key key; |
| 90 | }; |
| 91 | |
| 92 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 93 | * We use this hashed waitqueue instead of a normal wait_queue_t, so |
| 94 | * we can wake only the relevant ones (hashed queues may be shared). |
| 95 | * |
| 96 | * A futex_q has a woken state, just like tasks have TASK_RUNNING. |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 97 | * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 98 | * The order of wakup is always to make the first condition true, then |
Darren Hart | 73500ac | 2008-12-17 17:29:56 -0800 | [diff] [blame] | 99 | * wake up q->waiter, then make the second condition true. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 100 | */ |
| 101 | struct futex_q { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 102 | struct plist_node list; |
Thomas Gleixner | f1a11e0 | 2009-05-05 19:21:40 +0200 | [diff] [blame] | 103 | /* Waiter reference */ |
| 104 | struct task_struct *task; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 105 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 106 | /* Which hash list lock to use: */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 107 | spinlock_t *lock_ptr; |
| 108 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 109 | /* Key which the futex is hashed on: */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 110 | union futex_key key; |
| 111 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 112 | /* Optional priority inheritance state: */ |
| 113 | struct futex_pi_state *pi_state; |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 114 | |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 115 | /* rt_waiter storage for requeue_pi: */ |
| 116 | struct rt_mutex_waiter *rt_waiter; |
| 117 | |
Darren Hart | 84bc4af | 2009-08-13 17:36:53 -0700 | [diff] [blame] | 118 | /* The expected requeue pi target futex key: */ |
| 119 | union futex_key *requeue_pi_key; |
| 120 | |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 121 | /* Bitset for the optional bitmasked wakeup */ |
| 122 | u32 bitset; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 123 | }; |
| 124 | |
| 125 | /* |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 126 | * Hash buckets are shared by all the futex_keys that hash to the same |
| 127 | * location. Each key may have multiple futex_q structures, one for each task |
| 128 | * waiting on a futex. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | */ |
| 130 | struct futex_hash_bucket { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 131 | spinlock_t lock; |
| 132 | struct plist_head chain; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | }; |
| 134 | |
| 135 | static struct futex_hash_bucket futex_queues[1<<FUTEX_HASHBITS]; |
| 136 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 137 | /* |
| 138 | * We hash on the keys returned from get_futex_key (see below). |
| 139 | */ |
| 140 | static struct futex_hash_bucket *hash_futex(union futex_key *key) |
| 141 | { |
| 142 | u32 hash = jhash2((u32*)&key->both.word, |
| 143 | (sizeof(key->both.word)+sizeof(key->both.ptr))/4, |
| 144 | key->both.offset); |
| 145 | return &futex_queues[hash & ((1 << FUTEX_HASHBITS)-1)]; |
| 146 | } |
| 147 | |
| 148 | /* |
| 149 | * Return 1 if two futex_keys are equal, 0 otherwise. |
| 150 | */ |
| 151 | static inline int match_futex(union futex_key *key1, union futex_key *key2) |
| 152 | { |
| 153 | return (key1->both.word == key2->both.word |
| 154 | && key1->both.ptr == key2->both.ptr |
| 155 | && key1->both.offset == key2->both.offset); |
| 156 | } |
| 157 | |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 158 | /* |
| 159 | * Take a reference to the resource addressed by a key. |
| 160 | * Can be called while holding spinlocks. |
| 161 | * |
| 162 | */ |
| 163 | static void get_futex_key_refs(union futex_key *key) |
| 164 | { |
| 165 | if (!key->both.ptr) |
| 166 | return; |
| 167 | |
| 168 | switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { |
| 169 | case FUT_OFF_INODE: |
| 170 | atomic_inc(&key->shared.inode->i_count); |
| 171 | break; |
| 172 | case FUT_OFF_MMSHARED: |
| 173 | atomic_inc(&key->private.mm->mm_count); |
| 174 | break; |
| 175 | } |
| 176 | } |
| 177 | |
| 178 | /* |
| 179 | * Drop a reference to the resource addressed by a key. |
| 180 | * The hash bucket spinlock must not be held. |
| 181 | */ |
| 182 | static void drop_futex_key_refs(union futex_key *key) |
| 183 | { |
Darren Hart | 90621c4 | 2008-12-29 19:43:21 -0800 | [diff] [blame] | 184 | if (!key->both.ptr) { |
| 185 | /* If we're here then we tried to put a key we failed to get */ |
| 186 | WARN_ON_ONCE(1); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 187 | return; |
Darren Hart | 90621c4 | 2008-12-29 19:43:21 -0800 | [diff] [blame] | 188 | } |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 189 | |
| 190 | switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { |
| 191 | case FUT_OFF_INODE: |
| 192 | iput(key->shared.inode); |
| 193 | break; |
| 194 | case FUT_OFF_MMSHARED: |
| 195 | mmdrop(key->private.mm); |
| 196 | break; |
| 197 | } |
| 198 | } |
| 199 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 200 | /** |
| 201 | * get_futex_key - Get parameters which are the keys for a futex. |
| 202 | * @uaddr: virtual address of the futex |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 203 | * @fshared: 0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 204 | * @key: address where result is stored. |
Thomas Gleixner | 64d1304 | 2009-05-18 21:20:10 +0200 | [diff] [blame] | 205 | * @rw: mapping needs to be read/write (values: VERIFY_READ, VERIFY_WRITE) |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 206 | * |
| 207 | * Returns a negative error code or 0 |
| 208 | * The key words are stored in *key on success. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 209 | * |
Josef "Jeff" Sipek | f3a43f3 | 2006-12-08 02:36:43 -0800 | [diff] [blame] | 210 | * For shared mappings, it's (page->index, vma->vm_file->f_path.dentry->d_inode, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 211 | * offset_within_page). For private mappings, it's (uaddr, current->mm). |
| 212 | * We can usually work out the index without swapping in the page. |
| 213 | * |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 214 | * lock_page() might sleep, the caller should not hold a spinlock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 215 | */ |
Thomas Gleixner | 64d1304 | 2009-05-18 21:20:10 +0200 | [diff] [blame] | 216 | static int |
| 217 | get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 218 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 219 | unsigned long address = (unsigned long)uaddr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 220 | struct mm_struct *mm = current->mm; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 221 | struct page *page; |
| 222 | int err; |
| 223 | |
| 224 | /* |
| 225 | * The futex address must be "naturally" aligned. |
| 226 | */ |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 227 | key->both.offset = address % PAGE_SIZE; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 228 | if (unlikely((address % sizeof(u32)) != 0)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 229 | return -EINVAL; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 230 | address -= key->both.offset; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 231 | |
| 232 | /* |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 233 | * PROCESS_PRIVATE futexes are fast. |
| 234 | * As the mm cannot disappear under us and the 'key' only needs |
| 235 | * virtual address, we dont even have to find the underlying vma. |
| 236 | * Note : We do have to check 'uaddr' is a valid user address, |
| 237 | * but access_ok() should be faster than find_vma() |
| 238 | */ |
| 239 | if (!fshared) { |
Thomas Gleixner | 64d1304 | 2009-05-18 21:20:10 +0200 | [diff] [blame] | 240 | if (unlikely(!access_ok(rw, uaddr, sizeof(u32)))) |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 241 | return -EFAULT; |
| 242 | key->private.mm = mm; |
| 243 | key->private.address = address; |
Peter Zijlstra | 42569c3 | 2008-09-30 12:33:07 +0200 | [diff] [blame] | 244 | get_futex_key_refs(key); |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 245 | return 0; |
| 246 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 247 | |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 248 | again: |
Thomas Gleixner | 64d1304 | 2009-05-18 21:20:10 +0200 | [diff] [blame] | 249 | err = get_user_pages_fast(address, 1, rw == VERIFY_WRITE, &page); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 250 | if (err < 0) |
| 251 | return err; |
| 252 | |
Sonny Rao | ce2ae53 | 2009-07-10 18:13:13 -0500 | [diff] [blame] | 253 | page = compound_head(page); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 254 | lock_page(page); |
| 255 | if (!page->mapping) { |
| 256 | unlock_page(page); |
| 257 | put_page(page); |
| 258 | goto again; |
| 259 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 260 | |
| 261 | /* |
| 262 | * Private mappings are handled in a simple way. |
| 263 | * |
| 264 | * NOTE: When userspace waits on a MAP_SHARED mapping, even if |
| 265 | * it's a read-only handle, it's expected that futexes attach to |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 266 | * the object not the particular process. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 267 | */ |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 268 | if (PageAnon(page)) { |
| 269 | key->both.offset |= FUT_OFF_MMSHARED; /* ref taken on mm */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 270 | key->private.mm = mm; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 271 | key->private.address = address; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 272 | } else { |
| 273 | key->both.offset |= FUT_OFF_INODE; /* inode-based key */ |
| 274 | key->shared.inode = page->mapping->host; |
| 275 | key->shared.pgoff = page->index; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 276 | } |
| 277 | |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 278 | get_futex_key_refs(key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 279 | |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 280 | unlock_page(page); |
| 281 | put_page(page); |
| 282 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 283 | } |
| 284 | |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 285 | static inline |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 286 | void put_futex_key(int fshared, union futex_key *key) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 287 | { |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 288 | drop_futex_key_refs(key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 289 | } |
| 290 | |
Thomas Gleixner | d072599 | 2009-06-11 23:15:43 +0200 | [diff] [blame] | 291 | /* |
| 292 | * fault_in_user_writeable - fault in user address and verify RW access |
| 293 | * @uaddr: pointer to faulting user space address |
| 294 | * |
| 295 | * Slow path to fixup the fault we just took in the atomic write |
| 296 | * access to @uaddr. |
| 297 | * |
| 298 | * We have no generic implementation of a non destructive write to the |
| 299 | * user address. We know that we faulted in the atomic pagefault |
| 300 | * disabled section so we can as well avoid the #PF overhead by |
| 301 | * calling get_user_pages() right away. |
| 302 | */ |
| 303 | static int fault_in_user_writeable(u32 __user *uaddr) |
| 304 | { |
| 305 | int ret = get_user_pages(current, current->mm, (unsigned long)uaddr, |
Thomas Gleixner | aa71528 | 2009-06-25 14:27:58 +0200 | [diff] [blame] | 306 | 1, 1, 0, NULL, NULL); |
Thomas Gleixner | d072599 | 2009-06-11 23:15:43 +0200 | [diff] [blame] | 307 | return ret < 0 ? ret : 0; |
| 308 | } |
| 309 | |
Darren Hart | 4b1c486 | 2009-04-03 13:39:42 -0700 | [diff] [blame] | 310 | /** |
| 311 | * futex_top_waiter() - Return the highest priority waiter on a futex |
| 312 | * @hb: the hash bucket the futex_q's reside in |
| 313 | * @key: the futex key (to distinguish it from other futex futex_q's) |
| 314 | * |
| 315 | * Must be called with the hb lock held. |
| 316 | */ |
| 317 | static struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb, |
| 318 | union futex_key *key) |
| 319 | { |
| 320 | struct futex_q *this; |
| 321 | |
| 322 | plist_for_each_entry(this, &hb->chain, list) { |
| 323 | if (match_futex(&this->key, key)) |
| 324 | return this; |
| 325 | } |
| 326 | return NULL; |
| 327 | } |
| 328 | |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 329 | static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval) |
| 330 | { |
| 331 | u32 curval; |
| 332 | |
| 333 | pagefault_disable(); |
| 334 | curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval); |
| 335 | pagefault_enable(); |
| 336 | |
| 337 | return curval; |
| 338 | } |
| 339 | |
| 340 | static int get_futex_value_locked(u32 *dest, u32 __user *from) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 341 | { |
| 342 | int ret; |
| 343 | |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame] | 344 | pagefault_disable(); |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 345 | ret = __copy_from_user_inatomic(dest, from, sizeof(u32)); |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame] | 346 | pagefault_enable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 347 | |
| 348 | return ret ? -EFAULT : 0; |
| 349 | } |
| 350 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 351 | |
| 352 | /* |
| 353 | * PI code: |
| 354 | */ |
| 355 | static int refill_pi_state_cache(void) |
| 356 | { |
| 357 | struct futex_pi_state *pi_state; |
| 358 | |
| 359 | if (likely(current->pi_state_cache)) |
| 360 | return 0; |
| 361 | |
Burman Yan | 4668edc | 2006-12-06 20:38:51 -0800 | [diff] [blame] | 362 | pi_state = kzalloc(sizeof(*pi_state), GFP_KERNEL); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 363 | |
| 364 | if (!pi_state) |
| 365 | return -ENOMEM; |
| 366 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 367 | INIT_LIST_HEAD(&pi_state->list); |
| 368 | /* pi_mutex gets initialized later */ |
| 369 | pi_state->owner = NULL; |
| 370 | atomic_set(&pi_state->refcount, 1); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 371 | pi_state->key = FUTEX_KEY_INIT; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 372 | |
| 373 | current->pi_state_cache = pi_state; |
| 374 | |
| 375 | return 0; |
| 376 | } |
| 377 | |
| 378 | static struct futex_pi_state * alloc_pi_state(void) |
| 379 | { |
| 380 | struct futex_pi_state *pi_state = current->pi_state_cache; |
| 381 | |
| 382 | WARN_ON(!pi_state); |
| 383 | current->pi_state_cache = NULL; |
| 384 | |
| 385 | return pi_state; |
| 386 | } |
| 387 | |
| 388 | static void free_pi_state(struct futex_pi_state *pi_state) |
| 389 | { |
| 390 | if (!atomic_dec_and_test(&pi_state->refcount)) |
| 391 | return; |
| 392 | |
| 393 | /* |
| 394 | * If pi_state->owner is NULL, the owner is most probably dying |
| 395 | * and has cleaned up the pi_state already |
| 396 | */ |
| 397 | if (pi_state->owner) { |
| 398 | spin_lock_irq(&pi_state->owner->pi_lock); |
| 399 | list_del_init(&pi_state->list); |
| 400 | spin_unlock_irq(&pi_state->owner->pi_lock); |
| 401 | |
| 402 | rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner); |
| 403 | } |
| 404 | |
| 405 | if (current->pi_state_cache) |
| 406 | kfree(pi_state); |
| 407 | else { |
| 408 | /* |
| 409 | * pi_state->list is already empty. |
| 410 | * clear pi_state->owner. |
| 411 | * refcount is at 0 - put it back to 1. |
| 412 | */ |
| 413 | pi_state->owner = NULL; |
| 414 | atomic_set(&pi_state->refcount, 1); |
| 415 | current->pi_state_cache = pi_state; |
| 416 | } |
| 417 | } |
| 418 | |
| 419 | /* |
| 420 | * Look up the task based on what TID userspace gave us. |
| 421 | * We dont trust it. |
| 422 | */ |
| 423 | static struct task_struct * futex_find_get_task(pid_t pid) |
| 424 | { |
| 425 | struct task_struct *p; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 426 | const struct cred *cred = current_cred(), *pcred; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 427 | |
Oleg Nesterov | d359b54 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 428 | rcu_read_lock(); |
Pavel Emelyanov | 228ebcb | 2007-10-18 23:40:16 -0700 | [diff] [blame] | 429 | p = find_task_by_vpid(pid); |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 430 | if (!p) { |
Thomas Gleixner | a06381f | 2007-06-23 11:48:40 +0200 | [diff] [blame] | 431 | p = ERR_PTR(-ESRCH); |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 432 | } else { |
| 433 | pcred = __task_cred(p); |
| 434 | if (cred->euid != pcred->euid && |
| 435 | cred->euid != pcred->uid) |
| 436 | p = ERR_PTR(-ESRCH); |
| 437 | else |
| 438 | get_task_struct(p); |
| 439 | } |
Thomas Gleixner | a06381f | 2007-06-23 11:48:40 +0200 | [diff] [blame] | 440 | |
Oleg Nesterov | d359b54 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 441 | rcu_read_unlock(); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 442 | |
| 443 | return p; |
| 444 | } |
| 445 | |
| 446 | /* |
| 447 | * This task is holding PI mutexes at exit time => bad. |
| 448 | * Kernel cleans up PI-state, but userspace is likely hosed. |
| 449 | * (Robust-futex cleanup is separate and might save the day for userspace.) |
| 450 | */ |
| 451 | void exit_pi_state_list(struct task_struct *curr) |
| 452 | { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 453 | struct list_head *next, *head = &curr->pi_state_list; |
| 454 | struct futex_pi_state *pi_state; |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 455 | struct futex_hash_bucket *hb; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 456 | union futex_key key = FUTEX_KEY_INIT; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 457 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 458 | if (!futex_cmpxchg_enabled) |
| 459 | return; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 460 | /* |
| 461 | * We are a ZOMBIE and nobody can enqueue itself on |
| 462 | * pi_state_list anymore, but we have to be careful |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 463 | * versus waiters unqueueing themselves: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 464 | */ |
| 465 | spin_lock_irq(&curr->pi_lock); |
| 466 | while (!list_empty(head)) { |
| 467 | |
| 468 | next = head->next; |
| 469 | pi_state = list_entry(next, struct futex_pi_state, list); |
| 470 | key = pi_state->key; |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 471 | hb = hash_futex(&key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 472 | spin_unlock_irq(&curr->pi_lock); |
| 473 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 474 | spin_lock(&hb->lock); |
| 475 | |
| 476 | spin_lock_irq(&curr->pi_lock); |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 477 | /* |
| 478 | * We dropped the pi-lock, so re-check whether this |
| 479 | * task still owns the PI-state: |
| 480 | */ |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 481 | if (head->next != next) { |
| 482 | spin_unlock(&hb->lock); |
| 483 | continue; |
| 484 | } |
| 485 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 486 | WARN_ON(pi_state->owner != curr); |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 487 | WARN_ON(list_empty(&pi_state->list)); |
| 488 | list_del_init(&pi_state->list); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 489 | pi_state->owner = NULL; |
| 490 | spin_unlock_irq(&curr->pi_lock); |
| 491 | |
| 492 | rt_mutex_unlock(&pi_state->pi_mutex); |
| 493 | |
| 494 | spin_unlock(&hb->lock); |
| 495 | |
| 496 | spin_lock_irq(&curr->pi_lock); |
| 497 | } |
| 498 | spin_unlock_irq(&curr->pi_lock); |
| 499 | } |
| 500 | |
| 501 | static int |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 502 | lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, |
| 503 | union futex_key *key, struct futex_pi_state **ps) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 504 | { |
| 505 | struct futex_pi_state *pi_state = NULL; |
| 506 | struct futex_q *this, *next; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 507 | struct plist_head *head; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 508 | struct task_struct *p; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 509 | pid_t pid = uval & FUTEX_TID_MASK; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 510 | |
| 511 | head = &hb->chain; |
| 512 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 513 | plist_for_each_entry_safe(this, next, head, list) { |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 514 | if (match_futex(&this->key, key)) { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 515 | /* |
| 516 | * Another waiter already exists - bump up |
| 517 | * the refcount and return its pi_state: |
| 518 | */ |
| 519 | pi_state = this->pi_state; |
Thomas Gleixner | 06a9ec2 | 2006-07-10 04:44:30 -0700 | [diff] [blame] | 520 | /* |
| 521 | * Userspace might have messed up non PI and PI futexes |
| 522 | */ |
| 523 | if (unlikely(!pi_state)) |
| 524 | return -EINVAL; |
| 525 | |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 526 | WARN_ON(!atomic_read(&pi_state->refcount)); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 527 | WARN_ON(pid && pi_state->owner && |
| 528 | pi_state->owner->pid != pid); |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 529 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 530 | atomic_inc(&pi_state->refcount); |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 531 | *ps = pi_state; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 532 | |
| 533 | return 0; |
| 534 | } |
| 535 | } |
| 536 | |
| 537 | /* |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 538 | * We are the first waiter - try to look up the real owner and attach |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 539 | * the new pi_state to it, but bail out when TID = 0 |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 540 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 541 | if (!pid) |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 542 | return -ESRCH; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 543 | p = futex_find_get_task(pid); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 544 | if (IS_ERR(p)) |
| 545 | return PTR_ERR(p); |
| 546 | |
| 547 | /* |
| 548 | * We need to look at the task state flags to figure out, |
| 549 | * whether the task is exiting. To protect against the do_exit |
| 550 | * change of the task flags, we do this protected by |
| 551 | * p->pi_lock: |
| 552 | */ |
| 553 | spin_lock_irq(&p->pi_lock); |
| 554 | if (unlikely(p->flags & PF_EXITING)) { |
| 555 | /* |
| 556 | * The task is on the way out. When PF_EXITPIDONE is |
| 557 | * set, we know that the task has finished the |
| 558 | * cleanup: |
| 559 | */ |
| 560 | int ret = (p->flags & PF_EXITPIDONE) ? -ESRCH : -EAGAIN; |
| 561 | |
| 562 | spin_unlock_irq(&p->pi_lock); |
| 563 | put_task_struct(p); |
| 564 | return ret; |
| 565 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 566 | |
| 567 | pi_state = alloc_pi_state(); |
| 568 | |
| 569 | /* |
| 570 | * Initialize the pi_mutex in locked state and make 'p' |
| 571 | * the owner of it: |
| 572 | */ |
| 573 | rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p); |
| 574 | |
| 575 | /* Store the key for possible exit cleanups: */ |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 576 | pi_state->key = *key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 577 | |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 578 | WARN_ON(!list_empty(&pi_state->list)); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 579 | list_add(&pi_state->list, &p->pi_state_list); |
| 580 | pi_state->owner = p; |
| 581 | spin_unlock_irq(&p->pi_lock); |
| 582 | |
| 583 | put_task_struct(p); |
| 584 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 585 | *ps = pi_state; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 586 | |
| 587 | return 0; |
| 588 | } |
| 589 | |
Darren Hart | 1a52084 | 2009-04-03 13:39:52 -0700 | [diff] [blame] | 590 | /** |
| 591 | * futex_lock_pi_atomic() - atomic work required to acquire a pi aware futex |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 592 | * @uaddr: the pi futex user address |
| 593 | * @hb: the pi futex hash bucket |
| 594 | * @key: the futex key associated with uaddr and hb |
| 595 | * @ps: the pi_state pointer where we store the result of the |
| 596 | * lookup |
| 597 | * @task: the task to perform the atomic lock work for. This will |
| 598 | * be "current" except in the case of requeue pi. |
| 599 | * @set_waiters: force setting the FUTEX_WAITERS bit (1) or not (0) |
Darren Hart | 1a52084 | 2009-04-03 13:39:52 -0700 | [diff] [blame] | 600 | * |
| 601 | * Returns: |
| 602 | * 0 - ready to wait |
| 603 | * 1 - acquired the lock |
| 604 | * <0 - error |
| 605 | * |
| 606 | * The hb->lock and futex_key refs shall be held by the caller. |
| 607 | */ |
| 608 | static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb, |
| 609 | union futex_key *key, |
| 610 | struct futex_pi_state **ps, |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 611 | struct task_struct *task, int set_waiters) |
Darren Hart | 1a52084 | 2009-04-03 13:39:52 -0700 | [diff] [blame] | 612 | { |
| 613 | int lock_taken, ret, ownerdied = 0; |
| 614 | u32 uval, newval, curval; |
| 615 | |
| 616 | retry: |
| 617 | ret = lock_taken = 0; |
| 618 | |
| 619 | /* |
| 620 | * To avoid races, we attempt to take the lock here again |
| 621 | * (by doing a 0 -> TID atomic cmpxchg), while holding all |
| 622 | * the locks. It will most likely not succeed. |
| 623 | */ |
| 624 | newval = task_pid_vnr(task); |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 625 | if (set_waiters) |
| 626 | newval |= FUTEX_WAITERS; |
Darren Hart | 1a52084 | 2009-04-03 13:39:52 -0700 | [diff] [blame] | 627 | |
| 628 | curval = cmpxchg_futex_value_locked(uaddr, 0, newval); |
| 629 | |
| 630 | if (unlikely(curval == -EFAULT)) |
| 631 | return -EFAULT; |
| 632 | |
| 633 | /* |
| 634 | * Detect deadlocks. |
| 635 | */ |
| 636 | if ((unlikely((curval & FUTEX_TID_MASK) == task_pid_vnr(task)))) |
| 637 | return -EDEADLK; |
| 638 | |
| 639 | /* |
| 640 | * Surprise - we got the lock. Just return to userspace: |
| 641 | */ |
| 642 | if (unlikely(!curval)) |
| 643 | return 1; |
| 644 | |
| 645 | uval = curval; |
| 646 | |
| 647 | /* |
| 648 | * Set the FUTEX_WAITERS flag, so the owner will know it has someone |
| 649 | * to wake at the next unlock. |
| 650 | */ |
| 651 | newval = curval | FUTEX_WAITERS; |
| 652 | |
| 653 | /* |
| 654 | * There are two cases, where a futex might have no owner (the |
| 655 | * owner TID is 0): OWNER_DIED. We take over the futex in this |
| 656 | * case. We also do an unconditional take over, when the owner |
| 657 | * of the futex died. |
| 658 | * |
| 659 | * This is safe as we are protected by the hash bucket lock ! |
| 660 | */ |
| 661 | if (unlikely(ownerdied || !(curval & FUTEX_TID_MASK))) { |
| 662 | /* Keep the OWNER_DIED bit */ |
| 663 | newval = (curval & ~FUTEX_TID_MASK) | task_pid_vnr(task); |
| 664 | ownerdied = 0; |
| 665 | lock_taken = 1; |
| 666 | } |
| 667 | |
| 668 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
| 669 | |
| 670 | if (unlikely(curval == -EFAULT)) |
| 671 | return -EFAULT; |
| 672 | if (unlikely(curval != uval)) |
| 673 | goto retry; |
| 674 | |
| 675 | /* |
| 676 | * We took the lock due to owner died take over. |
| 677 | */ |
| 678 | if (unlikely(lock_taken)) |
| 679 | return 1; |
| 680 | |
| 681 | /* |
| 682 | * We dont have the lock. Look up the PI state (or create it if |
| 683 | * we are the first waiter): |
| 684 | */ |
| 685 | ret = lookup_pi_state(uval, hb, key, ps); |
| 686 | |
| 687 | if (unlikely(ret)) { |
| 688 | switch (ret) { |
| 689 | case -ESRCH: |
| 690 | /* |
| 691 | * No owner found for this futex. Check if the |
| 692 | * OWNER_DIED bit is set to figure out whether |
| 693 | * this is a robust futex or not. |
| 694 | */ |
| 695 | if (get_futex_value_locked(&curval, uaddr)) |
| 696 | return -EFAULT; |
| 697 | |
| 698 | /* |
| 699 | * We simply start over in case of a robust |
| 700 | * futex. The code above will take the futex |
| 701 | * and return happy. |
| 702 | */ |
| 703 | if (curval & FUTEX_OWNER_DIED) { |
| 704 | ownerdied = 1; |
| 705 | goto retry; |
| 706 | } |
| 707 | default: |
| 708 | break; |
| 709 | } |
| 710 | } |
| 711 | |
| 712 | return ret; |
| 713 | } |
| 714 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 715 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 716 | * The hash bucket lock must be held when this is called. |
| 717 | * Afterwards, the futex_q must not be accessed. |
| 718 | */ |
| 719 | static void wake_futex(struct futex_q *q) |
| 720 | { |
Thomas Gleixner | f1a11e0 | 2009-05-05 19:21:40 +0200 | [diff] [blame] | 721 | struct task_struct *p = q->task; |
| 722 | |
| 723 | /* |
| 724 | * We set q->lock_ptr = NULL _before_ we wake up the task. If |
| 725 | * a non futex wake up happens on another CPU then the task |
| 726 | * might exit and p would dereference a non existing task |
| 727 | * struct. Prevent this by holding a reference on p across the |
| 728 | * wake up. |
| 729 | */ |
| 730 | get_task_struct(p); |
| 731 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 732 | plist_del(&q->list, &q->list.plist); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 733 | /* |
Thomas Gleixner | f1a11e0 | 2009-05-05 19:21:40 +0200 | [diff] [blame] | 734 | * The waiting task can free the futex_q as soon as |
| 735 | * q->lock_ptr = NULL is written, without taking any locks. A |
| 736 | * memory barrier is required here to prevent the following |
| 737 | * store to lock_ptr from getting ahead of the plist_del. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 738 | */ |
Ralf Baechle | ccdea2f | 2006-12-06 20:40:26 -0800 | [diff] [blame] | 739 | smp_wmb(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 740 | q->lock_ptr = NULL; |
Thomas Gleixner | f1a11e0 | 2009-05-05 19:21:40 +0200 | [diff] [blame] | 741 | |
| 742 | wake_up_state(p, TASK_NORMAL); |
| 743 | put_task_struct(p); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 744 | } |
| 745 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 746 | static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this) |
| 747 | { |
| 748 | struct task_struct *new_owner; |
| 749 | struct futex_pi_state *pi_state = this->pi_state; |
| 750 | u32 curval, newval; |
| 751 | |
| 752 | if (!pi_state) |
| 753 | return -EINVAL; |
| 754 | |
Ingo Molnar | 21778867 | 2007-03-16 13:38:31 -0800 | [diff] [blame] | 755 | spin_lock(&pi_state->pi_mutex.wait_lock); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 756 | new_owner = rt_mutex_next_owner(&pi_state->pi_mutex); |
| 757 | |
| 758 | /* |
| 759 | * This happens when we have stolen the lock and the original |
| 760 | * pending owner did not enqueue itself back on the rt_mutex. |
| 761 | * Thats not a tragedy. We know that way, that a lock waiter |
| 762 | * is on the fly. We make the futex_q waiter the pending owner. |
| 763 | */ |
| 764 | if (!new_owner) |
| 765 | new_owner = this->task; |
| 766 | |
| 767 | /* |
| 768 | * We pass it to the next owner. (The WAITERS bit is always |
| 769 | * kept enabled while there is PI state around. We must also |
| 770 | * preserve the owner died bit.) |
| 771 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 772 | if (!(uval & FUTEX_OWNER_DIED)) { |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 773 | int ret = 0; |
| 774 | |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 775 | newval = FUTEX_WAITERS | task_pid_vnr(new_owner); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 776 | |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 777 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 778 | |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 779 | if (curval == -EFAULT) |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 780 | ret = -EFAULT; |
Thomas Gleixner | cde898f | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 781 | else if (curval != uval) |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 782 | ret = -EINVAL; |
| 783 | if (ret) { |
| 784 | spin_unlock(&pi_state->pi_mutex.wait_lock); |
| 785 | return ret; |
| 786 | } |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 787 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 788 | |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 789 | spin_lock_irq(&pi_state->owner->pi_lock); |
| 790 | WARN_ON(list_empty(&pi_state->list)); |
| 791 | list_del_init(&pi_state->list); |
| 792 | spin_unlock_irq(&pi_state->owner->pi_lock); |
| 793 | |
| 794 | spin_lock_irq(&new_owner->pi_lock); |
| 795 | WARN_ON(!list_empty(&pi_state->list)); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 796 | list_add(&pi_state->list, &new_owner->pi_state_list); |
| 797 | pi_state->owner = new_owner; |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 798 | spin_unlock_irq(&new_owner->pi_lock); |
| 799 | |
Ingo Molnar | 21778867 | 2007-03-16 13:38:31 -0800 | [diff] [blame] | 800 | spin_unlock(&pi_state->pi_mutex.wait_lock); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 801 | rt_mutex_unlock(&pi_state->pi_mutex); |
| 802 | |
| 803 | return 0; |
| 804 | } |
| 805 | |
| 806 | static int unlock_futex_pi(u32 __user *uaddr, u32 uval) |
| 807 | { |
| 808 | u32 oldval; |
| 809 | |
| 810 | /* |
| 811 | * There is no waiter, so we unlock the futex. The owner died |
| 812 | * bit has not to be preserved here. We are the owner: |
| 813 | */ |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 814 | oldval = cmpxchg_futex_value_locked(uaddr, uval, 0); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 815 | |
| 816 | if (oldval == -EFAULT) |
| 817 | return oldval; |
| 818 | if (oldval != uval) |
| 819 | return -EAGAIN; |
| 820 | |
| 821 | return 0; |
| 822 | } |
| 823 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 824 | /* |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 825 | * Express the locking dependencies for lockdep: |
| 826 | */ |
| 827 | static inline void |
| 828 | double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) |
| 829 | { |
| 830 | if (hb1 <= hb2) { |
| 831 | spin_lock(&hb1->lock); |
| 832 | if (hb1 < hb2) |
| 833 | spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); |
| 834 | } else { /* hb1 > hb2 */ |
| 835 | spin_lock(&hb2->lock); |
| 836 | spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); |
| 837 | } |
| 838 | } |
| 839 | |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 840 | static inline void |
| 841 | double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) |
| 842 | { |
Darren Hart | f061d35 | 2009-03-12 15:11:18 -0700 | [diff] [blame] | 843 | spin_unlock(&hb1->lock); |
Ingo Molnar | 88f502f | 2009-03-13 10:32:07 +0100 | [diff] [blame] | 844 | if (hb1 != hb2) |
| 845 | spin_unlock(&hb2->lock); |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 846 | } |
| 847 | |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 848 | /* |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 849 | * Wake up waiters matching bitset queued on this futex (uaddr). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 850 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 851 | static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 852 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 853 | struct futex_hash_bucket *hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 854 | struct futex_q *this, *next; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 855 | struct plist_head *head; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 856 | union futex_key key = FUTEX_KEY_INIT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 857 | int ret; |
| 858 | |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 859 | if (!bitset) |
| 860 | return -EINVAL; |
| 861 | |
Thomas Gleixner | 64d1304 | 2009-05-18 21:20:10 +0200 | [diff] [blame] | 862 | ret = get_futex_key(uaddr, fshared, &key, VERIFY_READ); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 863 | if (unlikely(ret != 0)) |
| 864 | goto out; |
| 865 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 866 | hb = hash_futex(&key); |
| 867 | spin_lock(&hb->lock); |
| 868 | head = &hb->chain; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 869 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 870 | plist_for_each_entry_safe(this, next, head, list) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 871 | if (match_futex (&this->key, &key)) { |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 872 | if (this->pi_state || this->rt_waiter) { |
Ingo Molnar | ed6f7b1 | 2006-07-01 04:35:46 -0700 | [diff] [blame] | 873 | ret = -EINVAL; |
| 874 | break; |
| 875 | } |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 876 | |
| 877 | /* Check if one of the bits is set in both bitsets */ |
| 878 | if (!(this->bitset & bitset)) |
| 879 | continue; |
| 880 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 881 | wake_futex(this); |
| 882 | if (++ret >= nr_wake) |
| 883 | break; |
| 884 | } |
| 885 | } |
| 886 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 887 | spin_unlock(&hb->lock); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 888 | put_futex_key(fshared, &key); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 889 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 890 | return ret; |
| 891 | } |
| 892 | |
| 893 | /* |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 894 | * Wake up all waiters hashed on the physical page that is mapped |
| 895 | * to this virtual address: |
| 896 | */ |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 897 | static int |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 898 | futex_wake_op(u32 __user *uaddr1, int fshared, u32 __user *uaddr2, |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 899 | int nr_wake, int nr_wake2, int op) |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 900 | { |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 901 | union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 902 | struct futex_hash_bucket *hb1, *hb2; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 903 | struct plist_head *head; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 904 | struct futex_q *this, *next; |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 905 | int ret, op_ret; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 906 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 907 | retry: |
Thomas Gleixner | 64d1304 | 2009-05-18 21:20:10 +0200 | [diff] [blame] | 908 | ret = get_futex_key(uaddr1, fshared, &key1, VERIFY_READ); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 909 | if (unlikely(ret != 0)) |
| 910 | goto out; |
Thomas Gleixner | 64d1304 | 2009-05-18 21:20:10 +0200 | [diff] [blame] | 911 | ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 912 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 913 | goto out_put_key1; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 914 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 915 | hb1 = hash_futex(&key1); |
| 916 | hb2 = hash_futex(&key2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 917 | |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 918 | double_lock_hb(hb1, hb2); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 919 | retry_private: |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 920 | op_ret = futex_atomic_op_inuser(op, uaddr2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 921 | if (unlikely(op_ret < 0)) { |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 922 | |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 923 | double_unlock_hb(hb1, hb2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 924 | |
David Howells | 7ee1dd3 | 2006-01-06 00:11:44 -0800 | [diff] [blame] | 925 | #ifndef CONFIG_MMU |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 926 | /* |
| 927 | * we don't get EFAULT from MMU faults if we don't have an MMU, |
| 928 | * but we might get them from range checking |
| 929 | */ |
David Howells | 7ee1dd3 | 2006-01-06 00:11:44 -0800 | [diff] [blame] | 930 | ret = op_ret; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 931 | goto out_put_keys; |
David Howells | 7ee1dd3 | 2006-01-06 00:11:44 -0800 | [diff] [blame] | 932 | #endif |
| 933 | |
David Gibson | 796f8d9 | 2005-11-07 00:59:33 -0800 | [diff] [blame] | 934 | if (unlikely(op_ret != -EFAULT)) { |
| 935 | ret = op_ret; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 936 | goto out_put_keys; |
David Gibson | 796f8d9 | 2005-11-07 00:59:33 -0800 | [diff] [blame] | 937 | } |
| 938 | |
Thomas Gleixner | d072599 | 2009-06-11 23:15:43 +0200 | [diff] [blame] | 939 | ret = fault_in_user_writeable(uaddr2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 940 | if (ret) |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 941 | goto out_put_keys; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 942 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 943 | if (!fshared) |
| 944 | goto retry_private; |
| 945 | |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 946 | put_futex_key(fshared, &key2); |
| 947 | put_futex_key(fshared, &key1); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 948 | goto retry; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 949 | } |
| 950 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 951 | head = &hb1->chain; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 952 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 953 | plist_for_each_entry_safe(this, next, head, list) { |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 954 | if (match_futex (&this->key, &key1)) { |
| 955 | wake_futex(this); |
| 956 | if (++ret >= nr_wake) |
| 957 | break; |
| 958 | } |
| 959 | } |
| 960 | |
| 961 | if (op_ret > 0) { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 962 | head = &hb2->chain; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 963 | |
| 964 | op_ret = 0; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 965 | plist_for_each_entry_safe(this, next, head, list) { |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 966 | if (match_futex (&this->key, &key2)) { |
| 967 | wake_futex(this); |
| 968 | if (++op_ret >= nr_wake2) |
| 969 | break; |
| 970 | } |
| 971 | } |
| 972 | ret += op_ret; |
| 973 | } |
| 974 | |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 975 | double_unlock_hb(hb1, hb2); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 976 | out_put_keys: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 977 | put_futex_key(fshared, &key2); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 978 | out_put_key1: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 979 | put_futex_key(fshared, &key1); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 980 | out: |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 981 | return ret; |
| 982 | } |
| 983 | |
Darren Hart | 9121e47 | 2009-04-03 13:40:31 -0700 | [diff] [blame] | 984 | /** |
| 985 | * requeue_futex() - Requeue a futex_q from one hb to another |
| 986 | * @q: the futex_q to requeue |
| 987 | * @hb1: the source hash_bucket |
| 988 | * @hb2: the target hash_bucket |
| 989 | * @key2: the new key for the requeued futex_q |
| 990 | */ |
| 991 | static inline |
| 992 | void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1, |
| 993 | struct futex_hash_bucket *hb2, union futex_key *key2) |
| 994 | { |
| 995 | |
| 996 | /* |
| 997 | * If key1 and key2 hash to the same bucket, no need to |
| 998 | * requeue. |
| 999 | */ |
| 1000 | if (likely(&hb1->chain != &hb2->chain)) { |
| 1001 | plist_del(&q->list, &hb1->chain); |
| 1002 | plist_add(&q->list, &hb2->chain); |
| 1003 | q->lock_ptr = &hb2->lock; |
| 1004 | #ifdef CONFIG_DEBUG_PI_LIST |
| 1005 | q->list.plist.lock = &hb2->lock; |
| 1006 | #endif |
| 1007 | } |
| 1008 | get_futex_key_refs(key2); |
| 1009 | q->key = *key2; |
| 1010 | } |
| 1011 | |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1012 | /** |
| 1013 | * requeue_pi_wake_futex() - Wake a task that acquired the lock during requeue |
| 1014 | * q: the futex_q |
| 1015 | * key: the key of the requeue target futex |
Darren Hart | beda2c7 | 2009-08-09 15:34:39 -0700 | [diff] [blame] | 1016 | * hb: the hash_bucket of the requeue target futex |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1017 | * |
| 1018 | * During futex_requeue, with requeue_pi=1, it is possible to acquire the |
| 1019 | * target futex if it is uncontended or via a lock steal. Set the futex_q key |
| 1020 | * to the requeue target futex so the waiter can detect the wakeup on the right |
| 1021 | * futex, but remove it from the hb and NULL the rt_waiter so it can detect |
Darren Hart | beda2c7 | 2009-08-09 15:34:39 -0700 | [diff] [blame] | 1022 | * atomic lock acquisition. Set the q->lock_ptr to the requeue target hb->lock |
| 1023 | * to protect access to the pi_state to fixup the owner later. Must be called |
| 1024 | * with both q->lock_ptr and hb->lock held. |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1025 | */ |
| 1026 | static inline |
Darren Hart | beda2c7 | 2009-08-09 15:34:39 -0700 | [diff] [blame] | 1027 | void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key, |
| 1028 | struct futex_hash_bucket *hb) |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1029 | { |
| 1030 | drop_futex_key_refs(&q->key); |
| 1031 | get_futex_key_refs(key); |
| 1032 | q->key = *key; |
| 1033 | |
| 1034 | WARN_ON(plist_node_empty(&q->list)); |
| 1035 | plist_del(&q->list, &q->list.plist); |
| 1036 | |
| 1037 | WARN_ON(!q->rt_waiter); |
| 1038 | q->rt_waiter = NULL; |
| 1039 | |
Darren Hart | beda2c7 | 2009-08-09 15:34:39 -0700 | [diff] [blame] | 1040 | q->lock_ptr = &hb->lock; |
| 1041 | #ifdef CONFIG_DEBUG_PI_LIST |
| 1042 | q->list.plist.lock = &hb->lock; |
| 1043 | #endif |
| 1044 | |
Thomas Gleixner | f1a11e0 | 2009-05-05 19:21:40 +0200 | [diff] [blame] | 1045 | wake_up_state(q->task, TASK_NORMAL); |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1046 | } |
| 1047 | |
| 1048 | /** |
| 1049 | * futex_proxy_trylock_atomic() - Attempt an atomic lock for the top waiter |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 1050 | * @pifutex: the user address of the to futex |
| 1051 | * @hb1: the from futex hash bucket, must be locked by the caller |
| 1052 | * @hb2: the to futex hash bucket, must be locked by the caller |
| 1053 | * @key1: the from futex key |
| 1054 | * @key2: the to futex key |
| 1055 | * @ps: address to store the pi_state pointer |
| 1056 | * @set_waiters: force setting the FUTEX_WAITERS bit (1) or not (0) |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1057 | * |
| 1058 | * Try and get the lock on behalf of the top waiter if we can do it atomically. |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 1059 | * Wake the top waiter if we succeed. If the caller specified set_waiters, |
| 1060 | * then direct futex_lock_pi_atomic() to force setting the FUTEX_WAITERS bit. |
| 1061 | * hb1 and hb2 must be held by the caller. |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1062 | * |
| 1063 | * Returns: |
| 1064 | * 0 - failed to acquire the lock atomicly |
| 1065 | * 1 - acquired the lock |
| 1066 | * <0 - error |
| 1067 | */ |
| 1068 | static int futex_proxy_trylock_atomic(u32 __user *pifutex, |
| 1069 | struct futex_hash_bucket *hb1, |
| 1070 | struct futex_hash_bucket *hb2, |
| 1071 | union futex_key *key1, union futex_key *key2, |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 1072 | struct futex_pi_state **ps, int set_waiters) |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1073 | { |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 1074 | struct futex_q *top_waiter = NULL; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1075 | u32 curval; |
| 1076 | int ret; |
| 1077 | |
| 1078 | if (get_futex_value_locked(&curval, pifutex)) |
| 1079 | return -EFAULT; |
| 1080 | |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 1081 | /* |
| 1082 | * Find the top_waiter and determine if there are additional waiters. |
| 1083 | * If the caller intends to requeue more than 1 waiter to pifutex, |
| 1084 | * force futex_lock_pi_atomic() to set the FUTEX_WAITERS bit now, |
| 1085 | * as we have means to handle the possible fault. If not, don't set |
| 1086 | * the bit unecessarily as it will force the subsequent unlock to enter |
| 1087 | * the kernel. |
| 1088 | */ |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1089 | top_waiter = futex_top_waiter(hb1, key1); |
| 1090 | |
| 1091 | /* There are no waiters, nothing for us to do. */ |
| 1092 | if (!top_waiter) |
| 1093 | return 0; |
| 1094 | |
Darren Hart | 84bc4af | 2009-08-13 17:36:53 -0700 | [diff] [blame] | 1095 | /* Ensure we requeue to the expected futex. */ |
| 1096 | if (!match_futex(top_waiter->requeue_pi_key, key2)) |
| 1097 | return -EINVAL; |
| 1098 | |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1099 | /* |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 1100 | * Try to take the lock for top_waiter. Set the FUTEX_WAITERS bit in |
| 1101 | * the contended case or if set_waiters is 1. The pi_state is returned |
| 1102 | * in ps in contended cases. |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1103 | */ |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 1104 | ret = futex_lock_pi_atomic(pifutex, hb2, key2, ps, top_waiter->task, |
| 1105 | set_waiters); |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1106 | if (ret == 1) |
Darren Hart | beda2c7 | 2009-08-09 15:34:39 -0700 | [diff] [blame] | 1107 | requeue_pi_wake_futex(top_waiter, key2, hb2); |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1108 | |
| 1109 | return ret; |
| 1110 | } |
| 1111 | |
| 1112 | /** |
| 1113 | * futex_requeue() - Requeue waiters from uaddr1 to uaddr2 |
| 1114 | * uaddr1: source futex user address |
| 1115 | * uaddr2: target futex user address |
| 1116 | * nr_wake: number of waiters to wake (must be 1 for requeue_pi) |
| 1117 | * nr_requeue: number of waiters to requeue (0-INT_MAX) |
| 1118 | * requeue_pi: if we are attempting to requeue from a non-pi futex to a |
| 1119 | * pi futex (pi to pi requeue is not supported) |
| 1120 | * |
| 1121 | * Requeue waiters on uaddr1 to uaddr2. In the requeue_pi case, try to acquire |
| 1122 | * uaddr2 atomically on behalf of the top waiter. |
| 1123 | * |
| 1124 | * Returns: |
| 1125 | * >=0 - on success, the number of tasks requeued or woken |
| 1126 | * <0 - on error |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1127 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1128 | static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2, |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1129 | int nr_wake, int nr_requeue, u32 *cmpval, |
| 1130 | int requeue_pi) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1131 | { |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1132 | union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1133 | int drop_count = 0, task_count = 0, ret; |
| 1134 | struct futex_pi_state *pi_state = NULL; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1135 | struct futex_hash_bucket *hb1, *hb2; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1136 | struct plist_head *head1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1137 | struct futex_q *this, *next; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1138 | u32 curval2; |
| 1139 | |
| 1140 | if (requeue_pi) { |
| 1141 | /* |
| 1142 | * requeue_pi requires a pi_state, try to allocate it now |
| 1143 | * without any locks in case it fails. |
| 1144 | */ |
| 1145 | if (refill_pi_state_cache()) |
| 1146 | return -ENOMEM; |
| 1147 | /* |
| 1148 | * requeue_pi must wake as many tasks as it can, up to nr_wake |
| 1149 | * + nr_requeue, since it acquires the rt_mutex prior to |
| 1150 | * returning to userspace, so as to not leave the rt_mutex with |
| 1151 | * waiters and no owner. However, second and third wake-ups |
| 1152 | * cannot be predicted as they involve race conditions with the |
| 1153 | * first wake and a fault while looking up the pi_state. Both |
| 1154 | * pthread_cond_signal() and pthread_cond_broadcast() should |
| 1155 | * use nr_wake=1. |
| 1156 | */ |
| 1157 | if (nr_wake != 1) |
| 1158 | return -EINVAL; |
| 1159 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1160 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1161 | retry: |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1162 | if (pi_state != NULL) { |
| 1163 | /* |
| 1164 | * We will have to lookup the pi_state again, so free this one |
| 1165 | * to keep the accounting correct. |
| 1166 | */ |
| 1167 | free_pi_state(pi_state); |
| 1168 | pi_state = NULL; |
| 1169 | } |
| 1170 | |
Thomas Gleixner | 64d1304 | 2009-05-18 21:20:10 +0200 | [diff] [blame] | 1171 | ret = get_futex_key(uaddr1, fshared, &key1, VERIFY_READ); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1172 | if (unlikely(ret != 0)) |
| 1173 | goto out; |
Thomas Gleixner | 521c180 | 2009-05-20 09:02:28 +0200 | [diff] [blame] | 1174 | ret = get_futex_key(uaddr2, fshared, &key2, |
| 1175 | requeue_pi ? VERIFY_WRITE : VERIFY_READ); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1176 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1177 | goto out_put_key1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1178 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1179 | hb1 = hash_futex(&key1); |
| 1180 | hb2 = hash_futex(&key2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1181 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1182 | retry_private: |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 1183 | double_lock_hb(hb1, hb2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1184 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1185 | if (likely(cmpval != NULL)) { |
| 1186 | u32 curval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1187 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1188 | ret = get_futex_value_locked(&curval, uaddr1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1189 | |
| 1190 | if (unlikely(ret)) { |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 1191 | double_unlock_hb(hb1, hb2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1192 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1193 | ret = get_user(curval, uaddr1); |
| 1194 | if (ret) |
| 1195 | goto out_put_keys; |
| 1196 | |
| 1197 | if (!fshared) |
| 1198 | goto retry_private; |
| 1199 | |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 1200 | put_futex_key(fshared, &key2); |
| 1201 | put_futex_key(fshared, &key1); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1202 | goto retry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1203 | } |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1204 | if (curval != *cmpval) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1205 | ret = -EAGAIN; |
| 1206 | goto out_unlock; |
| 1207 | } |
| 1208 | } |
| 1209 | |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1210 | if (requeue_pi && (task_count - nr_wake < nr_requeue)) { |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 1211 | /* |
| 1212 | * Attempt to acquire uaddr2 and wake the top waiter. If we |
| 1213 | * intend to requeue waiters, force setting the FUTEX_WAITERS |
| 1214 | * bit. We force this here where we are able to easily handle |
| 1215 | * faults rather in the requeue loop below. |
| 1216 | */ |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1217 | ret = futex_proxy_trylock_atomic(uaddr2, hb1, hb2, &key1, |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 1218 | &key2, &pi_state, nr_requeue); |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1219 | |
| 1220 | /* |
| 1221 | * At this point the top_waiter has either taken uaddr2 or is |
| 1222 | * waiting on it. If the former, then the pi_state will not |
| 1223 | * exist yet, look it up one more time to ensure we have a |
| 1224 | * reference to it. |
| 1225 | */ |
| 1226 | if (ret == 1) { |
| 1227 | WARN_ON(pi_state); |
| 1228 | task_count++; |
| 1229 | ret = get_futex_value_locked(&curval2, uaddr2); |
| 1230 | if (!ret) |
| 1231 | ret = lookup_pi_state(curval2, hb2, &key2, |
| 1232 | &pi_state); |
| 1233 | } |
| 1234 | |
| 1235 | switch (ret) { |
| 1236 | case 0: |
| 1237 | break; |
| 1238 | case -EFAULT: |
| 1239 | double_unlock_hb(hb1, hb2); |
| 1240 | put_futex_key(fshared, &key2); |
| 1241 | put_futex_key(fshared, &key1); |
Thomas Gleixner | d072599 | 2009-06-11 23:15:43 +0200 | [diff] [blame] | 1242 | ret = fault_in_user_writeable(uaddr2); |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1243 | if (!ret) |
| 1244 | goto retry; |
| 1245 | goto out; |
| 1246 | case -EAGAIN: |
| 1247 | /* The owner was exiting, try again. */ |
| 1248 | double_unlock_hb(hb1, hb2); |
| 1249 | put_futex_key(fshared, &key2); |
| 1250 | put_futex_key(fshared, &key1); |
| 1251 | cond_resched(); |
| 1252 | goto retry; |
| 1253 | default: |
| 1254 | goto out_unlock; |
| 1255 | } |
| 1256 | } |
| 1257 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1258 | head1 = &hb1->chain; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1259 | plist_for_each_entry_safe(this, next, head1, list) { |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1260 | if (task_count - nr_wake >= nr_requeue) |
| 1261 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1262 | |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1263 | if (!match_futex(&this->key, &key1)) |
| 1264 | continue; |
| 1265 | |
Darren Hart | 392741e | 2009-08-07 15:20:48 -0700 | [diff] [blame] | 1266 | /* |
| 1267 | * FUTEX_WAIT_REQEUE_PI and FUTEX_CMP_REQUEUE_PI should always |
| 1268 | * be paired with each other and no other futex ops. |
| 1269 | */ |
| 1270 | if ((requeue_pi && !this->rt_waiter) || |
| 1271 | (!requeue_pi && this->rt_waiter)) { |
| 1272 | ret = -EINVAL; |
| 1273 | break; |
| 1274 | } |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1275 | |
| 1276 | /* |
| 1277 | * Wake nr_wake waiters. For requeue_pi, if we acquired the |
| 1278 | * lock, we already woke the top_waiter. If not, it will be |
| 1279 | * woken by futex_unlock_pi(). |
| 1280 | */ |
| 1281 | if (++task_count <= nr_wake && !requeue_pi) { |
| 1282 | wake_futex(this); |
| 1283 | continue; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1284 | } |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1285 | |
Darren Hart | 84bc4af | 2009-08-13 17:36:53 -0700 | [diff] [blame] | 1286 | /* Ensure we requeue to the expected futex for requeue_pi. */ |
| 1287 | if (requeue_pi && !match_futex(this->requeue_pi_key, &key2)) { |
| 1288 | ret = -EINVAL; |
| 1289 | break; |
| 1290 | } |
| 1291 | |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1292 | /* |
| 1293 | * Requeue nr_requeue waiters and possibly one more in the case |
| 1294 | * of requeue_pi if we couldn't acquire the lock atomically. |
| 1295 | */ |
| 1296 | if (requeue_pi) { |
| 1297 | /* Prepare the waiter to take the rt_mutex. */ |
| 1298 | atomic_inc(&pi_state->refcount); |
| 1299 | this->pi_state = pi_state; |
| 1300 | ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex, |
| 1301 | this->rt_waiter, |
| 1302 | this->task, 1); |
| 1303 | if (ret == 1) { |
| 1304 | /* We got the lock. */ |
Darren Hart | beda2c7 | 2009-08-09 15:34:39 -0700 | [diff] [blame] | 1305 | requeue_pi_wake_futex(this, &key2, hb2); |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1306 | continue; |
| 1307 | } else if (ret) { |
| 1308 | /* -EDEADLK */ |
| 1309 | this->pi_state = NULL; |
| 1310 | free_pi_state(pi_state); |
| 1311 | goto out_unlock; |
| 1312 | } |
| 1313 | } |
| 1314 | requeue_futex(this, hb1, hb2, &key2); |
| 1315 | drop_count++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1316 | } |
| 1317 | |
| 1318 | out_unlock: |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 1319 | double_unlock_hb(hb1, hb2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1320 | |
Darren Hart | cd84a42 | 2009-04-02 14:19:38 -0700 | [diff] [blame] | 1321 | /* |
| 1322 | * drop_futex_key_refs() must be called outside the spinlocks. During |
| 1323 | * the requeue we moved futex_q's from the hash bucket at key1 to the |
| 1324 | * one at key2 and updated their key pointer. We no longer need to |
| 1325 | * hold the references to key1. |
| 1326 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1327 | while (--drop_count >= 0) |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1328 | drop_futex_key_refs(&key1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1329 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1330 | out_put_keys: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1331 | put_futex_key(fshared, &key2); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1332 | out_put_key1: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1333 | put_futex_key(fshared, &key1); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1334 | out: |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1335 | if (pi_state != NULL) |
| 1336 | free_pi_state(pi_state); |
| 1337 | return ret ? ret : task_count; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1338 | } |
| 1339 | |
| 1340 | /* The key must be already stored in q->key. */ |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1341 | static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1342 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1343 | struct futex_hash_bucket *hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1344 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1345 | get_futex_key_refs(&q->key); |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1346 | hb = hash_futex(&q->key); |
| 1347 | q->lock_ptr = &hb->lock; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1348 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1349 | spin_lock(&hb->lock); |
| 1350 | return hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1351 | } |
| 1352 | |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1353 | static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1354 | { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1355 | int prio; |
| 1356 | |
| 1357 | /* |
| 1358 | * The priority used to register this element is |
| 1359 | * - either the real thread-priority for the real-time threads |
| 1360 | * (i.e. threads with a priority lower than MAX_RT_PRIO) |
| 1361 | * - or MAX_RT_PRIO for non-RT threads. |
| 1362 | * Thus, all RT-threads are woken first in priority order, and |
| 1363 | * the others are woken last, in FIFO order. |
| 1364 | */ |
| 1365 | prio = min(current->normal_prio, MAX_RT_PRIO); |
| 1366 | |
| 1367 | plist_node_init(&q->list, prio); |
| 1368 | #ifdef CONFIG_DEBUG_PI_LIST |
| 1369 | q->list.plist.lock = &hb->lock; |
| 1370 | #endif |
| 1371 | plist_add(&q->list, &hb->chain); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1372 | q->task = current; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1373 | spin_unlock(&hb->lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1374 | } |
| 1375 | |
| 1376 | static inline void |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1377 | queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1378 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1379 | spin_unlock(&hb->lock); |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1380 | drop_futex_key_refs(&q->key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1381 | } |
| 1382 | |
| 1383 | /* |
| 1384 | * queue_me and unqueue_me must be called as a pair, each |
| 1385 | * exactly once. They are called with the hashed spinlock held. |
| 1386 | */ |
| 1387 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1388 | /* Return 1 if we were still queued (ie. 0 means we were woken) */ |
| 1389 | static int unqueue_me(struct futex_q *q) |
| 1390 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1391 | spinlock_t *lock_ptr; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1392 | int ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1393 | |
| 1394 | /* In the common case we don't take the spinlock, which is nice. */ |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1395 | retry: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1396 | lock_ptr = q->lock_ptr; |
Christian Borntraeger | e91467e | 2006-08-05 12:13:52 -0700 | [diff] [blame] | 1397 | barrier(); |
Stephen Hemminger | c80544d | 2007-10-18 03:07:05 -0700 | [diff] [blame] | 1398 | if (lock_ptr != NULL) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1399 | spin_lock(lock_ptr); |
| 1400 | /* |
| 1401 | * q->lock_ptr can change between reading it and |
| 1402 | * spin_lock(), causing us to take the wrong lock. This |
| 1403 | * corrects the race condition. |
| 1404 | * |
| 1405 | * Reasoning goes like this: if we have the wrong lock, |
| 1406 | * q->lock_ptr must have changed (maybe several times) |
| 1407 | * between reading it and the spin_lock(). It can |
| 1408 | * change again after the spin_lock() but only if it was |
| 1409 | * already changed before the spin_lock(). It cannot, |
| 1410 | * however, change back to the original value. Therefore |
| 1411 | * we can detect whether we acquired the correct lock. |
| 1412 | */ |
| 1413 | if (unlikely(lock_ptr != q->lock_ptr)) { |
| 1414 | spin_unlock(lock_ptr); |
| 1415 | goto retry; |
| 1416 | } |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1417 | WARN_ON(plist_node_empty(&q->list)); |
| 1418 | plist_del(&q->list, &q->list.plist); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1419 | |
| 1420 | BUG_ON(q->pi_state); |
| 1421 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1422 | spin_unlock(lock_ptr); |
| 1423 | ret = 1; |
| 1424 | } |
| 1425 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1426 | drop_futex_key_refs(&q->key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1427 | return ret; |
| 1428 | } |
| 1429 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1430 | /* |
| 1431 | * PI futexes can not be requeued and must remove themself from the |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1432 | * hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry |
| 1433 | * and dropped here. |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1434 | */ |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1435 | static void unqueue_me_pi(struct futex_q *q) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1436 | { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1437 | WARN_ON(plist_node_empty(&q->list)); |
| 1438 | plist_del(&q->list, &q->list.plist); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1439 | |
| 1440 | BUG_ON(!q->pi_state); |
| 1441 | free_pi_state(q->pi_state); |
| 1442 | q->pi_state = NULL; |
| 1443 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1444 | spin_unlock(q->lock_ptr); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1445 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1446 | drop_futex_key_refs(&q->key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1447 | } |
| 1448 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1449 | /* |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1450 | * Fixup the pi_state owner with the new owner. |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1451 | * |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1452 | * Must be called with hash bucket lock held and mm->sem held for non |
| 1453 | * private futexes. |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1454 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1455 | static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1456 | struct task_struct *newowner, int fshared) |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1457 | { |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1458 | u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1459 | struct futex_pi_state *pi_state = q->pi_state; |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1460 | struct task_struct *oldowner = pi_state->owner; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1461 | u32 uval, curval, newval; |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1462 | int ret; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1463 | |
| 1464 | /* Owner died? */ |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1465 | if (!pi_state->owner) |
| 1466 | newtid |= FUTEX_OWNER_DIED; |
| 1467 | |
| 1468 | /* |
| 1469 | * We are here either because we stole the rtmutex from the |
| 1470 | * pending owner or we are the pending owner which failed to |
| 1471 | * get the rtmutex. We have to replace the pending owner TID |
| 1472 | * in the user space variable. This must be atomic as we have |
| 1473 | * to preserve the owner died bit here. |
| 1474 | * |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 1475 | * Note: We write the user space value _before_ changing the pi_state |
| 1476 | * because we can fault here. Imagine swapped out pages or a fork |
| 1477 | * that marked all the anonymous memory readonly for cow. |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1478 | * |
| 1479 | * Modifying pi_state _before_ the user space value would |
| 1480 | * leave the pi_state in an inconsistent state when we fault |
| 1481 | * here, because we need to drop the hash bucket lock to |
| 1482 | * handle the fault. This might be observed in the PID check |
| 1483 | * in lookup_pi_state. |
| 1484 | */ |
| 1485 | retry: |
| 1486 | if (get_futex_value_locked(&uval, uaddr)) |
| 1487 | goto handle_fault; |
| 1488 | |
| 1489 | while (1) { |
| 1490 | newval = (uval & FUTEX_OWNER_DIED) | newtid; |
| 1491 | |
| 1492 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
| 1493 | |
| 1494 | if (curval == -EFAULT) |
| 1495 | goto handle_fault; |
| 1496 | if (curval == uval) |
| 1497 | break; |
| 1498 | uval = curval; |
| 1499 | } |
| 1500 | |
| 1501 | /* |
| 1502 | * We fixed up user space. Now we need to fix the pi_state |
| 1503 | * itself. |
| 1504 | */ |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1505 | if (pi_state->owner != NULL) { |
| 1506 | spin_lock_irq(&pi_state->owner->pi_lock); |
| 1507 | WARN_ON(list_empty(&pi_state->list)); |
| 1508 | list_del_init(&pi_state->list); |
| 1509 | spin_unlock_irq(&pi_state->owner->pi_lock); |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1510 | } |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1511 | |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1512 | pi_state->owner = newowner; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1513 | |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1514 | spin_lock_irq(&newowner->pi_lock); |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1515 | WARN_ON(!list_empty(&pi_state->list)); |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1516 | list_add(&pi_state->list, &newowner->pi_state_list); |
| 1517 | spin_unlock_irq(&newowner->pi_lock); |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1518 | return 0; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1519 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1520 | /* |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1521 | * To handle the page fault we need to drop the hash bucket |
| 1522 | * lock here. That gives the other task (either the pending |
| 1523 | * owner itself or the task which stole the rtmutex) the |
| 1524 | * chance to try the fixup of the pi_state. So once we are |
| 1525 | * back from handling the fault we need to check the pi_state |
| 1526 | * after reacquiring the hash bucket lock and before trying to |
| 1527 | * do another fixup. When the fixup has been done already we |
| 1528 | * simply return. |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1529 | */ |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1530 | handle_fault: |
| 1531 | spin_unlock(q->lock_ptr); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1532 | |
Thomas Gleixner | d072599 | 2009-06-11 23:15:43 +0200 | [diff] [blame] | 1533 | ret = fault_in_user_writeable(uaddr); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1534 | |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1535 | spin_lock(q->lock_ptr); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1536 | |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1537 | /* |
| 1538 | * Check if someone else fixed it for us: |
| 1539 | */ |
| 1540 | if (pi_state->owner != oldowner) |
| 1541 | return 0; |
| 1542 | |
| 1543 | if (ret) |
| 1544 | return ret; |
| 1545 | |
| 1546 | goto retry; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1547 | } |
| 1548 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1549 | /* |
| 1550 | * In case we must use restart_block to restart a futex_wait, |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1551 | * we encode in the 'flags' shared capability |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1552 | */ |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1553 | #define FLAGS_SHARED 0x01 |
| 1554 | #define FLAGS_CLOCKRT 0x02 |
Darren Hart | a72188d | 2009-04-03 13:40:22 -0700 | [diff] [blame] | 1555 | #define FLAGS_HAS_TIMEOUT 0x04 |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1556 | |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1557 | static long futex_wait_restart(struct restart_block *restart); |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1558 | |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1559 | /** |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1560 | * fixup_owner() - Post lock pi_state and corner case management |
| 1561 | * @uaddr: user address of the futex |
| 1562 | * @fshared: whether the futex is shared (1) or not (0) |
| 1563 | * @q: futex_q (contains pi_state and access to the rt_mutex) |
| 1564 | * @locked: if the attempt to take the rt_mutex succeeded (1) or not (0) |
| 1565 | * |
| 1566 | * After attempting to lock an rt_mutex, this function is called to cleanup |
| 1567 | * the pi_state owner as well as handle race conditions that may allow us to |
| 1568 | * acquire the lock. Must be called with the hb lock held. |
| 1569 | * |
| 1570 | * Returns: |
| 1571 | * 1 - success, lock taken |
| 1572 | * 0 - success, lock not taken |
| 1573 | * <0 - on error (-EFAULT) |
| 1574 | */ |
| 1575 | static int fixup_owner(u32 __user *uaddr, int fshared, struct futex_q *q, |
| 1576 | int locked) |
| 1577 | { |
| 1578 | struct task_struct *owner; |
| 1579 | int ret = 0; |
| 1580 | |
| 1581 | if (locked) { |
| 1582 | /* |
| 1583 | * Got the lock. We might not be the anticipated owner if we |
| 1584 | * did a lock-steal - fix up the PI-state in that case: |
| 1585 | */ |
| 1586 | if (q->pi_state->owner != current) |
| 1587 | ret = fixup_pi_state_owner(uaddr, q, current, fshared); |
| 1588 | goto out; |
| 1589 | } |
| 1590 | |
| 1591 | /* |
| 1592 | * Catch the rare case, where the lock was released when we were on the |
| 1593 | * way back before we locked the hash bucket. |
| 1594 | */ |
| 1595 | if (q->pi_state->owner == current) { |
| 1596 | /* |
| 1597 | * Try to get the rt_mutex now. This might fail as some other |
| 1598 | * task acquired the rt_mutex after we removed ourself from the |
| 1599 | * rt_mutex waiters list. |
| 1600 | */ |
| 1601 | if (rt_mutex_trylock(&q->pi_state->pi_mutex)) { |
| 1602 | locked = 1; |
| 1603 | goto out; |
| 1604 | } |
| 1605 | |
| 1606 | /* |
| 1607 | * pi_state is incorrect, some other task did a lock steal and |
| 1608 | * we returned due to timeout or signal without taking the |
| 1609 | * rt_mutex. Too late. We can access the rt_mutex_owner without |
| 1610 | * locking, as the other task is now blocked on the hash bucket |
| 1611 | * lock. Fix the state up. |
| 1612 | */ |
| 1613 | owner = rt_mutex_owner(&q->pi_state->pi_mutex); |
| 1614 | ret = fixup_pi_state_owner(uaddr, q, owner, fshared); |
| 1615 | goto out; |
| 1616 | } |
| 1617 | |
| 1618 | /* |
| 1619 | * Paranoia check. If we did not take the lock, then we should not be |
| 1620 | * the owner, nor the pending owner, of the rt_mutex. |
| 1621 | */ |
| 1622 | if (rt_mutex_owner(&q->pi_state->pi_mutex) == current) |
| 1623 | printk(KERN_ERR "fixup_owner: ret = %d pi-mutex: %p " |
| 1624 | "pi-state %p\n", ret, |
| 1625 | q->pi_state->pi_mutex.owner, |
| 1626 | q->pi_state->owner); |
| 1627 | |
| 1628 | out: |
| 1629 | return ret ? ret : locked; |
| 1630 | } |
| 1631 | |
| 1632 | /** |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1633 | * futex_wait_queue_me() - queue_me() and wait for wakeup, timeout, or signal |
| 1634 | * @hb: the futex hash bucket, must be locked by the caller |
| 1635 | * @q: the futex_q to queue up on |
| 1636 | * @timeout: the prepared hrtimer_sleeper, or null for no timeout |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1637 | */ |
| 1638 | static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q, |
Thomas Gleixner | f1a11e0 | 2009-05-05 19:21:40 +0200 | [diff] [blame] | 1639 | struct hrtimer_sleeper *timeout) |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1640 | { |
| 1641 | queue_me(q, hb); |
| 1642 | |
| 1643 | /* |
| 1644 | * There might have been scheduling since the queue_me(), as we |
| 1645 | * cannot hold a spinlock across the get_user() in case it |
| 1646 | * faults, and we cannot just set TASK_INTERRUPTIBLE state when |
Thomas Gleixner | f1a11e0 | 2009-05-05 19:21:40 +0200 | [diff] [blame] | 1647 | * queueing ourselves into the futex hash. This code thus has to |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1648 | * rely on the futex_wake() code removing us from hash when it |
| 1649 | * wakes us up. |
| 1650 | */ |
Thomas Gleixner | f1a11e0 | 2009-05-05 19:21:40 +0200 | [diff] [blame] | 1651 | set_current_state(TASK_INTERRUPTIBLE); |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1652 | |
| 1653 | /* Arm the timer */ |
| 1654 | if (timeout) { |
| 1655 | hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS); |
| 1656 | if (!hrtimer_active(&timeout->timer)) |
| 1657 | timeout->task = NULL; |
| 1658 | } |
| 1659 | |
| 1660 | /* |
| 1661 | * !plist_node_empty() is safe here without any lock. |
| 1662 | * q.lock_ptr != 0 is not safe, because of ordering against wakeup. |
| 1663 | */ |
| 1664 | if (likely(!plist_node_empty(&q->list))) { |
| 1665 | /* |
| 1666 | * If the timer has already expired, current will already be |
| 1667 | * flagged for rescheduling. Only call schedule if there |
| 1668 | * is no timeout, or if it has yet to expire. |
| 1669 | */ |
| 1670 | if (!timeout || timeout->task) |
| 1671 | schedule(); |
| 1672 | } |
| 1673 | __set_current_state(TASK_RUNNING); |
| 1674 | } |
| 1675 | |
Darren Hart | f801073 | 2009-04-03 13:40:40 -0700 | [diff] [blame] | 1676 | /** |
| 1677 | * futex_wait_setup() - Prepare to wait on a futex |
| 1678 | * @uaddr: the futex userspace address |
| 1679 | * @val: the expected value |
| 1680 | * @fshared: whether the futex is shared (1) or not (0) |
| 1681 | * @q: the associated futex_q |
| 1682 | * @hb: storage for hash_bucket pointer to be returned to caller |
| 1683 | * |
| 1684 | * Setup the futex_q and locate the hash_bucket. Get the futex value and |
| 1685 | * compare it with the expected value. Handle atomic faults internally. |
| 1686 | * Return with the hb lock held and a q.key reference on success, and unlocked |
| 1687 | * with no q.key reference on failure. |
| 1688 | * |
| 1689 | * Returns: |
| 1690 | * 0 - uaddr contains val and hb has been locked |
| 1691 | * <1 - -EFAULT or -EWOULDBLOCK (uaddr does not contain val) and hb is unlcoked |
| 1692 | */ |
| 1693 | static int futex_wait_setup(u32 __user *uaddr, u32 val, int fshared, |
| 1694 | struct futex_q *q, struct futex_hash_bucket **hb) |
| 1695 | { |
| 1696 | u32 uval; |
| 1697 | int ret; |
| 1698 | |
| 1699 | /* |
| 1700 | * Access the page AFTER the hash-bucket is locked. |
| 1701 | * Order is important: |
| 1702 | * |
| 1703 | * Userspace waiter: val = var; if (cond(val)) futex_wait(&var, val); |
| 1704 | * Userspace waker: if (cond(var)) { var = new; futex_wake(&var); } |
| 1705 | * |
| 1706 | * The basic logical guarantee of a futex is that it blocks ONLY |
| 1707 | * if cond(var) is known to be true at the time of blocking, for |
| 1708 | * any cond. If we queued after testing *uaddr, that would open |
| 1709 | * a race condition where we could block indefinitely with |
| 1710 | * cond(var) false, which would violate the guarantee. |
| 1711 | * |
| 1712 | * A consequence is that futex_wait() can return zero and absorb |
| 1713 | * a wakeup when *uaddr != val on entry to the syscall. This is |
| 1714 | * rare, but normal. |
| 1715 | */ |
| 1716 | retry: |
| 1717 | q->key = FUTEX_KEY_INIT; |
Thomas Gleixner | 521c180 | 2009-05-20 09:02:28 +0200 | [diff] [blame] | 1718 | ret = get_futex_key(uaddr, fshared, &q->key, VERIFY_READ); |
Darren Hart | f801073 | 2009-04-03 13:40:40 -0700 | [diff] [blame] | 1719 | if (unlikely(ret != 0)) |
Darren Hart | a5a2a0c | 2009-04-10 09:50:05 -0700 | [diff] [blame] | 1720 | return ret; |
Darren Hart | f801073 | 2009-04-03 13:40:40 -0700 | [diff] [blame] | 1721 | |
| 1722 | retry_private: |
| 1723 | *hb = queue_lock(q); |
| 1724 | |
| 1725 | ret = get_futex_value_locked(&uval, uaddr); |
| 1726 | |
| 1727 | if (ret) { |
| 1728 | queue_unlock(q, *hb); |
| 1729 | |
| 1730 | ret = get_user(uval, uaddr); |
| 1731 | if (ret) |
| 1732 | goto out; |
| 1733 | |
| 1734 | if (!fshared) |
| 1735 | goto retry_private; |
| 1736 | |
| 1737 | put_futex_key(fshared, &q->key); |
| 1738 | goto retry; |
| 1739 | } |
| 1740 | |
| 1741 | if (uval != val) { |
| 1742 | queue_unlock(q, *hb); |
| 1743 | ret = -EWOULDBLOCK; |
| 1744 | } |
| 1745 | |
| 1746 | out: |
| 1747 | if (ret) |
| 1748 | put_futex_key(fshared, &q->key); |
| 1749 | return ret; |
| 1750 | } |
| 1751 | |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1752 | static int futex_wait(u32 __user *uaddr, int fshared, |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1753 | u32 val, ktime_t *abs_time, u32 bitset, int clockrt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1754 | { |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1755 | struct hrtimer_sleeper timeout, *to = NULL; |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1756 | struct restart_block *restart; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1757 | struct futex_hash_bucket *hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1758 | struct futex_q q; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1759 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1760 | |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1761 | if (!bitset) |
| 1762 | return -EINVAL; |
| 1763 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1764 | q.pi_state = NULL; |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1765 | q.bitset = bitset; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1766 | q.rt_waiter = NULL; |
Darren Hart | 84bc4af | 2009-08-13 17:36:53 -0700 | [diff] [blame] | 1767 | q.requeue_pi_key = NULL; |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1768 | |
| 1769 | if (abs_time) { |
| 1770 | to = &timeout; |
| 1771 | |
| 1772 | hrtimer_init_on_stack(&to->timer, clockrt ? CLOCK_REALTIME : |
| 1773 | CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 1774 | hrtimer_init_sleeper(to, current); |
| 1775 | hrtimer_set_expires_range_ns(&to->timer, *abs_time, |
| 1776 | current->timer_slack_ns); |
| 1777 | } |
| 1778 | |
Darren Hart | f801073 | 2009-04-03 13:40:40 -0700 | [diff] [blame] | 1779 | /* Prepare to wait on uaddr. */ |
| 1780 | ret = futex_wait_setup(uaddr, val, fshared, &q, &hb); |
| 1781 | if (ret) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1782 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1783 | |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1784 | /* queue_me and wait for wakeup, timeout, or a signal. */ |
Thomas Gleixner | f1a11e0 | 2009-05-05 19:21:40 +0200 | [diff] [blame] | 1785 | futex_wait_queue_me(hb, &q, to); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1786 | |
| 1787 | /* If we were woken (and unqueued), we succeeded, whatever. */ |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1788 | ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1789 | if (!unqueue_me(&q)) |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1790 | goto out_put_key; |
| 1791 | ret = -ETIMEDOUT; |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1792 | if (to && !to->task) |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1793 | goto out_put_key; |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1794 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1795 | /* |
| 1796 | * We expect signal_pending(current), but another thread may |
| 1797 | * have handled it for us already. |
| 1798 | */ |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1799 | ret = -ERESTARTSYS; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1800 | if (!abs_time) |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1801 | goto out_put_key; |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1802 | |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1803 | restart = ¤t_thread_info()->restart_block; |
| 1804 | restart->fn = futex_wait_restart; |
| 1805 | restart->futex.uaddr = (u32 *)uaddr; |
| 1806 | restart->futex.val = val; |
| 1807 | restart->futex.time = abs_time->tv64; |
| 1808 | restart->futex.bitset = bitset; |
Darren Hart | a72188d | 2009-04-03 13:40:22 -0700 | [diff] [blame] | 1809 | restart->futex.flags = FLAGS_HAS_TIMEOUT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1810 | |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1811 | if (fshared) |
| 1812 | restart->futex.flags |= FLAGS_SHARED; |
| 1813 | if (clockrt) |
| 1814 | restart->futex.flags |= FLAGS_CLOCKRT; |
| 1815 | |
| 1816 | ret = -ERESTART_RESTARTBLOCK; |
| 1817 | |
| 1818 | out_put_key: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1819 | put_futex_key(fshared, &q.key); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1820 | out: |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1821 | if (to) { |
| 1822 | hrtimer_cancel(&to->timer); |
| 1823 | destroy_hrtimer_on_stack(&to->timer); |
| 1824 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1825 | return ret; |
| 1826 | } |
| 1827 | |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1828 | |
| 1829 | static long futex_wait_restart(struct restart_block *restart) |
| 1830 | { |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1831 | u32 __user *uaddr = (u32 __user *)restart->futex.uaddr; |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1832 | int fshared = 0; |
Darren Hart | a72188d | 2009-04-03 13:40:22 -0700 | [diff] [blame] | 1833 | ktime_t t, *tp = NULL; |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1834 | |
Darren Hart | a72188d | 2009-04-03 13:40:22 -0700 | [diff] [blame] | 1835 | if (restart->futex.flags & FLAGS_HAS_TIMEOUT) { |
| 1836 | t.tv64 = restart->futex.time; |
| 1837 | tp = &t; |
| 1838 | } |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1839 | restart->fn = do_no_restart_syscall; |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1840 | if (restart->futex.flags & FLAGS_SHARED) |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1841 | fshared = 1; |
Darren Hart | a72188d | 2009-04-03 13:40:22 -0700 | [diff] [blame] | 1842 | return (long)futex_wait(uaddr, fshared, restart->futex.val, tp, |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1843 | restart->futex.bitset, |
| 1844 | restart->futex.flags & FLAGS_CLOCKRT); |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1845 | } |
| 1846 | |
| 1847 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1848 | /* |
| 1849 | * Userspace tried a 0 -> TID atomic transition of the futex value |
| 1850 | * and failed. The kernel side here does the whole locking operation: |
| 1851 | * if there are waiters then it will block, it does PI, etc. (Due to |
| 1852 | * races the kernel might see a 0 value of the futex too.) |
| 1853 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1854 | static int futex_lock_pi(u32 __user *uaddr, int fshared, |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1855 | int detect, ktime_t *time, int trylock) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1856 | { |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1857 | struct hrtimer_sleeper timeout, *to = NULL; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1858 | struct futex_hash_bucket *hb; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1859 | struct futex_q q; |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1860 | int res, ret; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1861 | |
| 1862 | if (refill_pi_state_cache()) |
| 1863 | return -ENOMEM; |
| 1864 | |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1865 | if (time) { |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1866 | to = &timeout; |
Thomas Gleixner | 237fc6e | 2008-04-30 00:55:04 -0700 | [diff] [blame] | 1867 | hrtimer_init_on_stack(&to->timer, CLOCK_REALTIME, |
| 1868 | HRTIMER_MODE_ABS); |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1869 | hrtimer_init_sleeper(to, current); |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 1870 | hrtimer_set_expires(&to->timer, *time); |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1871 | } |
| 1872 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1873 | q.pi_state = NULL; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 1874 | q.rt_waiter = NULL; |
Darren Hart | 84bc4af | 2009-08-13 17:36:53 -0700 | [diff] [blame] | 1875 | q.requeue_pi_key = NULL; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1876 | retry: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1877 | q.key = FUTEX_KEY_INIT; |
Thomas Gleixner | 64d1304 | 2009-05-18 21:20:10 +0200 | [diff] [blame] | 1878 | ret = get_futex_key(uaddr, fshared, &q.key, VERIFY_WRITE); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1879 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1880 | goto out; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1881 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1882 | retry_private: |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1883 | hb = queue_lock(&q); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1884 | |
Darren Hart | bab5bc9 | 2009-04-07 23:23:50 -0700 | [diff] [blame] | 1885 | ret = futex_lock_pi_atomic(uaddr, hb, &q.key, &q.pi_state, current, 0); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1886 | if (unlikely(ret)) { |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1887 | switch (ret) { |
Darren Hart | 1a52084 | 2009-04-03 13:39:52 -0700 | [diff] [blame] | 1888 | case 1: |
| 1889 | /* We got the lock. */ |
| 1890 | ret = 0; |
| 1891 | goto out_unlock_put_key; |
| 1892 | case -EFAULT: |
| 1893 | goto uaddr_faulted; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1894 | case -EAGAIN: |
| 1895 | /* |
| 1896 | * Task is exiting and we just wait for the |
| 1897 | * exit to complete. |
| 1898 | */ |
| 1899 | queue_unlock(&q, hb); |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 1900 | put_futex_key(fshared, &q.key); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1901 | cond_resched(); |
| 1902 | goto retry; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1903 | default: |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1904 | goto out_unlock_put_key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1905 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1906 | } |
| 1907 | |
| 1908 | /* |
| 1909 | * Only actually queue now that the atomic ops are done: |
| 1910 | */ |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1911 | queue_me(&q, hb); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1912 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1913 | WARN_ON(!q.pi_state); |
| 1914 | /* |
| 1915 | * Block on the PI mutex: |
| 1916 | */ |
| 1917 | if (!trylock) |
| 1918 | ret = rt_mutex_timed_lock(&q.pi_state->pi_mutex, to, 1); |
| 1919 | else { |
| 1920 | ret = rt_mutex_trylock(&q.pi_state->pi_mutex); |
| 1921 | /* Fixup the trylock return value: */ |
| 1922 | ret = ret ? 0 : -EWOULDBLOCK; |
| 1923 | } |
| 1924 | |
Vernon Mauery | a99e4e4 | 2006-07-01 04:35:42 -0700 | [diff] [blame] | 1925 | spin_lock(q.lock_ptr); |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1926 | /* |
| 1927 | * Fixup the pi_state owner and possibly acquire the lock if we |
| 1928 | * haven't already. |
| 1929 | */ |
| 1930 | res = fixup_owner(uaddr, fshared, &q, !ret); |
| 1931 | /* |
| 1932 | * If fixup_owner() returned an error, proprogate that. If it acquired |
| 1933 | * the lock, clear our -ETIMEDOUT or -EINTR. |
| 1934 | */ |
| 1935 | if (res) |
| 1936 | ret = (res < 0) ? res : 0; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1937 | |
Darren Hart | e8f6386 | 2009-03-12 00:56:06 -0700 | [diff] [blame] | 1938 | /* |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1939 | * If fixup_owner() faulted and was unable to handle the fault, unlock |
| 1940 | * it and return the fault to userspace. |
Darren Hart | e8f6386 | 2009-03-12 00:56:06 -0700 | [diff] [blame] | 1941 | */ |
| 1942 | if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current)) |
| 1943 | rt_mutex_unlock(&q.pi_state->pi_mutex); |
| 1944 | |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1945 | /* Unqueue and drop the lock */ |
| 1946 | unqueue_me_pi(&q); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1947 | |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1948 | goto out; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1949 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1950 | out_unlock_put_key: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1951 | queue_unlock(&q, hb); |
| 1952 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1953 | out_put_key: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1954 | put_futex_key(fshared, &q.key); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1955 | out: |
Thomas Gleixner | 237fc6e | 2008-04-30 00:55:04 -0700 | [diff] [blame] | 1956 | if (to) |
| 1957 | destroy_hrtimer_on_stack(&to->timer); |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1958 | return ret != -EINTR ? ret : -ERESTARTNOINTR; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1959 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1960 | uaddr_faulted: |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1961 | queue_unlock(&q, hb); |
| 1962 | |
Thomas Gleixner | d072599 | 2009-06-11 23:15:43 +0200 | [diff] [blame] | 1963 | ret = fault_in_user_writeable(uaddr); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1964 | if (ret) |
| 1965 | goto out_put_key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1966 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1967 | if (!fshared) |
| 1968 | goto retry_private; |
| 1969 | |
| 1970 | put_futex_key(fshared, &q.key); |
| 1971 | goto retry; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1972 | } |
| 1973 | |
| 1974 | /* |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1975 | * Userspace attempted a TID -> 0 atomic transition, and failed. |
| 1976 | * This is the in-kernel slowpath: we look up the PI state (if any), |
| 1977 | * and do the rt-mutex unlock. |
| 1978 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1979 | static int futex_unlock_pi(u32 __user *uaddr, int fshared) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1980 | { |
| 1981 | struct futex_hash_bucket *hb; |
| 1982 | struct futex_q *this, *next; |
| 1983 | u32 uval; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1984 | struct plist_head *head; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1985 | union futex_key key = FUTEX_KEY_INIT; |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1986 | int ret; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1987 | |
| 1988 | retry: |
| 1989 | if (get_user(uval, uaddr)) |
| 1990 | return -EFAULT; |
| 1991 | /* |
| 1992 | * We release only a lock we actually own: |
| 1993 | */ |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1994 | if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current)) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1995 | return -EPERM; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1996 | |
Thomas Gleixner | 64d1304 | 2009-05-18 21:20:10 +0200 | [diff] [blame] | 1997 | ret = get_futex_key(uaddr, fshared, &key, VERIFY_WRITE); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1998 | if (unlikely(ret != 0)) |
| 1999 | goto out; |
| 2000 | |
| 2001 | hb = hash_futex(&key); |
| 2002 | spin_lock(&hb->lock); |
| 2003 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2004 | /* |
| 2005 | * To avoid races, try to do the TID -> 0 atomic transition |
| 2006 | * again. If it succeeds then we can return without waking |
| 2007 | * anyone else up: |
| 2008 | */ |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 2009 | if (!(uval & FUTEX_OWNER_DIED)) |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 2010 | uval = cmpxchg_futex_value_locked(uaddr, task_pid_vnr(current), 0); |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 2011 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2012 | |
| 2013 | if (unlikely(uval == -EFAULT)) |
| 2014 | goto pi_faulted; |
| 2015 | /* |
| 2016 | * Rare case: we managed to release the lock atomically, |
| 2017 | * no need to wake anyone else up: |
| 2018 | */ |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 2019 | if (unlikely(uval == task_pid_vnr(current))) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2020 | goto out_unlock; |
| 2021 | |
| 2022 | /* |
| 2023 | * Ok, other tasks may need to be woken up - check waiters |
| 2024 | * and do the wakeup if necessary: |
| 2025 | */ |
| 2026 | head = &hb->chain; |
| 2027 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 2028 | plist_for_each_entry_safe(this, next, head, list) { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2029 | if (!match_futex (&this->key, &key)) |
| 2030 | continue; |
| 2031 | ret = wake_futex_pi(uaddr, uval, this); |
| 2032 | /* |
| 2033 | * The atomic access to the futex value |
| 2034 | * generated a pagefault, so retry the |
| 2035 | * user-access and the wakeup: |
| 2036 | */ |
| 2037 | if (ret == -EFAULT) |
| 2038 | goto pi_faulted; |
| 2039 | goto out_unlock; |
| 2040 | } |
| 2041 | /* |
| 2042 | * No waiters - kernel unlocks the futex: |
| 2043 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2044 | if (!(uval & FUTEX_OWNER_DIED)) { |
| 2045 | ret = unlock_futex_pi(uaddr, uval); |
| 2046 | if (ret == -EFAULT) |
| 2047 | goto pi_faulted; |
| 2048 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2049 | |
| 2050 | out_unlock: |
| 2051 | spin_unlock(&hb->lock); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 2052 | put_futex_key(fshared, &key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2053 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 2054 | out: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2055 | return ret; |
| 2056 | |
| 2057 | pi_faulted: |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 2058 | spin_unlock(&hb->lock); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 2059 | put_futex_key(fshared, &key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2060 | |
Thomas Gleixner | d072599 | 2009-06-11 23:15:43 +0200 | [diff] [blame] | 2061 | ret = fault_in_user_writeable(uaddr); |
Darren Hart | b568636 | 2008-12-18 15:06:34 -0800 | [diff] [blame] | 2062 | if (!ret) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2063 | goto retry; |
| 2064 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2065 | return ret; |
| 2066 | } |
| 2067 | |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2068 | /** |
| 2069 | * handle_early_requeue_pi_wakeup() - Detect early wakeup on the initial futex |
| 2070 | * @hb: the hash_bucket futex_q was original enqueued on |
| 2071 | * @q: the futex_q woken while waiting to be requeued |
| 2072 | * @key2: the futex_key of the requeue target futex |
| 2073 | * @timeout: the timeout associated with the wait (NULL if none) |
| 2074 | * |
| 2075 | * Detect if the task was woken on the initial futex as opposed to the requeue |
| 2076 | * target futex. If so, determine if it was a timeout or a signal that caused |
| 2077 | * the wakeup and return the appropriate error code to the caller. Must be |
| 2078 | * called with the hb lock held. |
| 2079 | * |
| 2080 | * Returns |
| 2081 | * 0 - no early wakeup detected |
Thomas Gleixner | 1c840c1 | 2009-05-20 09:22:40 +0200 | [diff] [blame] | 2082 | * <0 - -ETIMEDOUT or -ERESTARTNOINTR |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2083 | */ |
| 2084 | static inline |
| 2085 | int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb, |
| 2086 | struct futex_q *q, union futex_key *key2, |
| 2087 | struct hrtimer_sleeper *timeout) |
| 2088 | { |
| 2089 | int ret = 0; |
| 2090 | |
| 2091 | /* |
| 2092 | * With the hb lock held, we avoid races while we process the wakeup. |
| 2093 | * We only need to hold hb (and not hb2) to ensure atomicity as the |
| 2094 | * wakeup code can't change q.key from uaddr to uaddr2 if we hold hb. |
| 2095 | * It can't be requeued from uaddr2 to something else since we don't |
| 2096 | * support a PI aware source futex for requeue. |
| 2097 | */ |
| 2098 | if (!match_futex(&q->key, key2)) { |
| 2099 | WARN_ON(q->lock_ptr && (&hb->lock != q->lock_ptr)); |
| 2100 | /* |
| 2101 | * We were woken prior to requeue by a timeout or a signal. |
| 2102 | * Unqueue the futex_q and determine which it was. |
| 2103 | */ |
| 2104 | plist_del(&q->list, &q->list.plist); |
| 2105 | drop_futex_key_refs(&q->key); |
| 2106 | |
| 2107 | if (timeout && !timeout->task) |
| 2108 | ret = -ETIMEDOUT; |
Thomas Gleixner | 1c840c1 | 2009-05-20 09:22:40 +0200 | [diff] [blame] | 2109 | else |
| 2110 | ret = -ERESTARTNOINTR; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2111 | } |
| 2112 | return ret; |
| 2113 | } |
| 2114 | |
| 2115 | /** |
| 2116 | * futex_wait_requeue_pi() - Wait on uaddr and take uaddr2 |
| 2117 | * @uaddr: the futex we initialyl wait on (non-pi) |
| 2118 | * @fshared: whether the futexes are shared (1) or not (0). They must be |
| 2119 | * the same type, no requeueing from private to shared, etc. |
| 2120 | * @val: the expected value of uaddr |
| 2121 | * @abs_time: absolute timeout |
| 2122 | * @bitset: 32 bit wakeup bitset set by userspace, defaults to all. |
| 2123 | * @clockrt: whether to use CLOCK_REALTIME (1) or CLOCK_MONOTONIC (0) |
| 2124 | * @uaddr2: the pi futex we will take prior to returning to user-space |
| 2125 | * |
| 2126 | * The caller will wait on uaddr and will be requeued by futex_requeue() to |
| 2127 | * uaddr2 which must be PI aware. Normal wakeup will wake on uaddr2 and |
| 2128 | * complete the acquisition of the rt_mutex prior to returning to userspace. |
| 2129 | * This ensures the rt_mutex maintains an owner when it has waiters; without |
| 2130 | * one, the pi logic wouldn't know which task to boost/deboost, if there was a |
| 2131 | * need to. |
| 2132 | * |
| 2133 | * We call schedule in futex_wait_queue_me() when we enqueue and return there |
| 2134 | * via the following: |
| 2135 | * 1) wakeup on uaddr2 after an atomic lock acquisition by futex_requeue() |
Darren Hart | cc6db4e | 2009-07-31 16:20:10 -0700 | [diff] [blame] | 2136 | * 2) wakeup on uaddr2 after a requeue |
| 2137 | * 3) signal |
| 2138 | * 4) timeout |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2139 | * |
Darren Hart | cc6db4e | 2009-07-31 16:20:10 -0700 | [diff] [blame] | 2140 | * If 3, cleanup and return -ERESTARTNOINTR. |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2141 | * |
| 2142 | * If 2, we may then block on trying to take the rt_mutex and return via: |
| 2143 | * 5) successful lock |
| 2144 | * 6) signal |
| 2145 | * 7) timeout |
| 2146 | * 8) other lock acquisition failure |
| 2147 | * |
Darren Hart | cc6db4e | 2009-07-31 16:20:10 -0700 | [diff] [blame] | 2148 | * If 6, return -EWOULDBLOCK (restarting the syscall would do the same). |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2149 | * |
| 2150 | * If 4 or 7, we cleanup and return with -ETIMEDOUT. |
| 2151 | * |
| 2152 | * Returns: |
| 2153 | * 0 - On success |
| 2154 | * <0 - On error |
| 2155 | */ |
| 2156 | static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared, |
| 2157 | u32 val, ktime_t *abs_time, u32 bitset, |
| 2158 | int clockrt, u32 __user *uaddr2) |
| 2159 | { |
| 2160 | struct hrtimer_sleeper timeout, *to = NULL; |
| 2161 | struct rt_mutex_waiter rt_waiter; |
| 2162 | struct rt_mutex *pi_mutex = NULL; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2163 | struct futex_hash_bucket *hb; |
| 2164 | union futex_key key2; |
| 2165 | struct futex_q q; |
| 2166 | int res, ret; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2167 | |
| 2168 | if (!bitset) |
| 2169 | return -EINVAL; |
| 2170 | |
| 2171 | if (abs_time) { |
| 2172 | to = &timeout; |
| 2173 | hrtimer_init_on_stack(&to->timer, clockrt ? CLOCK_REALTIME : |
| 2174 | CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 2175 | hrtimer_init_sleeper(to, current); |
| 2176 | hrtimer_set_expires_range_ns(&to->timer, *abs_time, |
| 2177 | current->timer_slack_ns); |
| 2178 | } |
| 2179 | |
| 2180 | /* |
| 2181 | * The waiter is allocated on our stack, manipulated by the requeue |
| 2182 | * code while we sleep on uaddr. |
| 2183 | */ |
| 2184 | debug_rt_mutex_init_waiter(&rt_waiter); |
| 2185 | rt_waiter.task = NULL; |
| 2186 | |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2187 | key2 = FUTEX_KEY_INIT; |
Thomas Gleixner | 521c180 | 2009-05-20 09:02:28 +0200 | [diff] [blame] | 2188 | ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE); |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2189 | if (unlikely(ret != 0)) |
| 2190 | goto out; |
| 2191 | |
Darren Hart | 84bc4af | 2009-08-13 17:36:53 -0700 | [diff] [blame] | 2192 | q.pi_state = NULL; |
| 2193 | q.bitset = bitset; |
| 2194 | q.rt_waiter = &rt_waiter; |
| 2195 | q.requeue_pi_key = &key2; |
| 2196 | |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2197 | /* Prepare to wait on uaddr. */ |
| 2198 | ret = futex_wait_setup(uaddr, val, fshared, &q, &hb); |
Thomas Gleixner | c8b15a7 | 2009-05-20 09:18:50 +0200 | [diff] [blame] | 2199 | if (ret) |
| 2200 | goto out_key2; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2201 | |
| 2202 | /* Queue the futex_q, drop the hb lock, wait for wakeup. */ |
Thomas Gleixner | f1a11e0 | 2009-05-05 19:21:40 +0200 | [diff] [blame] | 2203 | futex_wait_queue_me(hb, &q, to); |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2204 | |
| 2205 | spin_lock(&hb->lock); |
| 2206 | ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to); |
| 2207 | spin_unlock(&hb->lock); |
| 2208 | if (ret) |
| 2209 | goto out_put_keys; |
| 2210 | |
| 2211 | /* |
| 2212 | * In order for us to be here, we know our q.key == key2, and since |
| 2213 | * we took the hb->lock above, we also know that futex_requeue() has |
| 2214 | * completed and we no longer have to concern ourselves with a wakeup |
| 2215 | * race with the atomic proxy lock acquition by the requeue code. |
| 2216 | */ |
| 2217 | |
| 2218 | /* Check if the requeue code acquired the second futex for us. */ |
| 2219 | if (!q.rt_waiter) { |
| 2220 | /* |
| 2221 | * Got the lock. We might not be the anticipated owner if we |
| 2222 | * did a lock-steal - fix up the PI-state in that case. |
| 2223 | */ |
| 2224 | if (q.pi_state && (q.pi_state->owner != current)) { |
| 2225 | spin_lock(q.lock_ptr); |
| 2226 | ret = fixup_pi_state_owner(uaddr2, &q, current, |
| 2227 | fshared); |
| 2228 | spin_unlock(q.lock_ptr); |
| 2229 | } |
| 2230 | } else { |
| 2231 | /* |
| 2232 | * We have been woken up by futex_unlock_pi(), a timeout, or a |
| 2233 | * signal. futex_unlock_pi() will not destroy the lock_ptr nor |
| 2234 | * the pi_state. |
| 2235 | */ |
| 2236 | WARN_ON(!&q.pi_state); |
| 2237 | pi_mutex = &q.pi_state->pi_mutex; |
| 2238 | ret = rt_mutex_finish_proxy_lock(pi_mutex, to, &rt_waiter, 1); |
| 2239 | debug_rt_mutex_free_waiter(&rt_waiter); |
| 2240 | |
| 2241 | spin_lock(q.lock_ptr); |
| 2242 | /* |
| 2243 | * Fixup the pi_state owner and possibly acquire the lock if we |
| 2244 | * haven't already. |
| 2245 | */ |
| 2246 | res = fixup_owner(uaddr2, fshared, &q, !ret); |
| 2247 | /* |
| 2248 | * If fixup_owner() returned an error, proprogate that. If it |
| 2249 | * acquired the lock, clear our -ETIMEDOUT or -EINTR. |
| 2250 | */ |
| 2251 | if (res) |
| 2252 | ret = (res < 0) ? res : 0; |
| 2253 | |
| 2254 | /* Unqueue and drop the lock. */ |
| 2255 | unqueue_me_pi(&q); |
| 2256 | } |
| 2257 | |
| 2258 | /* |
| 2259 | * If fixup_pi_state_owner() faulted and was unable to handle the |
| 2260 | * fault, unlock the rt_mutex and return the fault to userspace. |
| 2261 | */ |
| 2262 | if (ret == -EFAULT) { |
| 2263 | if (rt_mutex_owner(pi_mutex) == current) |
| 2264 | rt_mutex_unlock(pi_mutex); |
| 2265 | } else if (ret == -EINTR) { |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2266 | /* |
Darren Hart | cc6db4e | 2009-07-31 16:20:10 -0700 | [diff] [blame] | 2267 | * We've already been requeued, but cannot restart by calling |
| 2268 | * futex_lock_pi() directly. We could restart this syscall, but |
| 2269 | * it would detect that the user space "val" changed and return |
| 2270 | * -EWOULDBLOCK. Save the overhead of the restart and return |
| 2271 | * -EWOULDBLOCK directly. |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2272 | */ |
Thomas Gleixner | 2070887 | 2009-05-19 23:04:59 +0200 | [diff] [blame] | 2273 | ret = -EWOULDBLOCK; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2274 | } |
| 2275 | |
| 2276 | out_put_keys: |
| 2277 | put_futex_key(fshared, &q.key); |
Thomas Gleixner | c8b15a7 | 2009-05-20 09:18:50 +0200 | [diff] [blame] | 2278 | out_key2: |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2279 | put_futex_key(fshared, &key2); |
| 2280 | |
| 2281 | out: |
| 2282 | if (to) { |
| 2283 | hrtimer_cancel(&to->timer); |
| 2284 | destroy_hrtimer_on_stack(&to->timer); |
| 2285 | } |
| 2286 | return ret; |
| 2287 | } |
| 2288 | |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2289 | /* |
| 2290 | * Support for robust futexes: the kernel cleans up held futexes at |
| 2291 | * thread exit time. |
| 2292 | * |
| 2293 | * Implementation: user-space maintains a per-thread list of locks it |
| 2294 | * is holding. Upon do_exit(), the kernel carefully walks this list, |
| 2295 | * and marks all locks that are owned by this thread with the |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2296 | * FUTEX_OWNER_DIED bit, and wakes up a waiter (if any). The list is |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2297 | * always manipulated with the lock held, so the list is private and |
| 2298 | * per-thread. Userspace also maintains a per-thread 'list_op_pending' |
| 2299 | * field, to allow the kernel to clean up if the thread dies after |
| 2300 | * acquiring the lock, but just before it could have added itself to |
| 2301 | * the list. There can only be one such pending lock. |
| 2302 | */ |
| 2303 | |
| 2304 | /** |
| 2305 | * sys_set_robust_list - set the robust-futex list head of a task |
| 2306 | * @head: pointer to the list-head |
| 2307 | * @len: length of the list-head, as userspace expects |
| 2308 | */ |
Heiko Carstens | 836f92a | 2009-01-14 14:14:33 +0100 | [diff] [blame] | 2309 | SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head, |
| 2310 | size_t, len) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2311 | { |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2312 | if (!futex_cmpxchg_enabled) |
| 2313 | return -ENOSYS; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2314 | /* |
| 2315 | * The kernel knows only one size for now: |
| 2316 | */ |
| 2317 | if (unlikely(len != sizeof(*head))) |
| 2318 | return -EINVAL; |
| 2319 | |
| 2320 | current->robust_list = head; |
| 2321 | |
| 2322 | return 0; |
| 2323 | } |
| 2324 | |
| 2325 | /** |
| 2326 | * sys_get_robust_list - get the robust-futex list head of a task |
| 2327 | * @pid: pid of the process [zero for current task] |
| 2328 | * @head_ptr: pointer to a list-head pointer, the kernel fills it in |
| 2329 | * @len_ptr: pointer to a length field, the kernel fills in the header size |
| 2330 | */ |
Heiko Carstens | 836f92a | 2009-01-14 14:14:33 +0100 | [diff] [blame] | 2331 | SYSCALL_DEFINE3(get_robust_list, int, pid, |
| 2332 | struct robust_list_head __user * __user *, head_ptr, |
| 2333 | size_t __user *, len_ptr) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2334 | { |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 2335 | struct robust_list_head __user *head; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2336 | unsigned long ret; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 2337 | const struct cred *cred = current_cred(), *pcred; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2338 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2339 | if (!futex_cmpxchg_enabled) |
| 2340 | return -ENOSYS; |
| 2341 | |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2342 | if (!pid) |
| 2343 | head = current->robust_list; |
| 2344 | else { |
| 2345 | struct task_struct *p; |
| 2346 | |
| 2347 | ret = -ESRCH; |
Oleg Nesterov | aaa2a97 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 2348 | rcu_read_lock(); |
Pavel Emelyanov | 228ebcb | 2007-10-18 23:40:16 -0700 | [diff] [blame] | 2349 | p = find_task_by_vpid(pid); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2350 | if (!p) |
| 2351 | goto err_unlock; |
| 2352 | ret = -EPERM; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 2353 | pcred = __task_cred(p); |
| 2354 | if (cred->euid != pcred->euid && |
| 2355 | cred->euid != pcred->uid && |
David Howells | 76aac0e | 2008-11-14 10:39:12 +1100 | [diff] [blame] | 2356 | !capable(CAP_SYS_PTRACE)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2357 | goto err_unlock; |
| 2358 | head = p->robust_list; |
Oleg Nesterov | aaa2a97 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 2359 | rcu_read_unlock(); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2360 | } |
| 2361 | |
| 2362 | if (put_user(sizeof(*head), len_ptr)) |
| 2363 | return -EFAULT; |
| 2364 | return put_user(head, head_ptr); |
| 2365 | |
| 2366 | err_unlock: |
Oleg Nesterov | aaa2a97 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 2367 | rcu_read_unlock(); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2368 | |
| 2369 | return ret; |
| 2370 | } |
| 2371 | |
| 2372 | /* |
| 2373 | * Process a futex-list entry, check whether it's owned by the |
| 2374 | * dying task, and do notification if so: |
| 2375 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2376 | int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2377 | { |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2378 | u32 uval, nval, mval; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2379 | |
Ingo Molnar | 8f17d3a | 2006-03-27 01:16:27 -0800 | [diff] [blame] | 2380 | retry: |
| 2381 | if (get_user(uval, uaddr)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2382 | return -1; |
| 2383 | |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 2384 | if ((uval & FUTEX_TID_MASK) == task_pid_vnr(curr)) { |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2385 | /* |
| 2386 | * Ok, this dying thread is truly holding a futex |
| 2387 | * of interest. Set the OWNER_DIED bit atomically |
| 2388 | * via cmpxchg, and if the value had FUTEX_WAITERS |
| 2389 | * set, wake up a waiter (if any). (We have to do a |
| 2390 | * futex_wake() even if OWNER_DIED is already set - |
| 2391 | * to handle the rare but possible case of recursive |
| 2392 | * thread-death.) The rest of the cleanup is done in |
| 2393 | * userspace. |
| 2394 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2395 | mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; |
| 2396 | nval = futex_atomic_cmpxchg_inatomic(uaddr, uval, mval); |
| 2397 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2398 | if (nval == -EFAULT) |
| 2399 | return -1; |
| 2400 | |
| 2401 | if (nval != uval) |
Ingo Molnar | 8f17d3a | 2006-03-27 01:16:27 -0800 | [diff] [blame] | 2402 | goto retry; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2403 | |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2404 | /* |
| 2405 | * Wake robust non-PI futexes here. The wakeup of |
| 2406 | * PI futexes happens in exit_pi_state(): |
| 2407 | */ |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 2408 | if (!pi && (uval & FUTEX_WAITERS)) |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 2409 | futex_wake(uaddr, 1, 1, FUTEX_BITSET_MATCH_ANY); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2410 | } |
| 2411 | return 0; |
| 2412 | } |
| 2413 | |
| 2414 | /* |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2415 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: |
| 2416 | */ |
| 2417 | static inline int fetch_robust_entry(struct robust_list __user **entry, |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 2418 | struct robust_list __user * __user *head, |
| 2419 | int *pi) |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2420 | { |
| 2421 | unsigned long uentry; |
| 2422 | |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 2423 | if (get_user(uentry, (unsigned long __user *)head)) |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2424 | return -EFAULT; |
| 2425 | |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 2426 | *entry = (void __user *)(uentry & ~1UL); |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2427 | *pi = uentry & 1; |
| 2428 | |
| 2429 | return 0; |
| 2430 | } |
| 2431 | |
| 2432 | /* |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2433 | * Walk curr->robust_list (very carefully, it's a userspace list!) |
| 2434 | * and mark any locks found there dead, and notify any waiters. |
| 2435 | * |
| 2436 | * We silently return on any sign of list-walking problem. |
| 2437 | */ |
| 2438 | void exit_robust_list(struct task_struct *curr) |
| 2439 | { |
| 2440 | struct robust_list_head __user *head = curr->robust_list; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 2441 | struct robust_list __user *entry, *next_entry, *pending; |
| 2442 | unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2443 | unsigned long futex_offset; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 2444 | int rc; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2445 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2446 | if (!futex_cmpxchg_enabled) |
| 2447 | return; |
| 2448 | |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2449 | /* |
| 2450 | * Fetch the list head (which was registered earlier, via |
| 2451 | * sys_set_robust_list()): |
| 2452 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2453 | if (fetch_robust_entry(&entry, &head->list.next, &pi)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2454 | return; |
| 2455 | /* |
| 2456 | * Fetch the relative futex offset: |
| 2457 | */ |
| 2458 | if (get_user(futex_offset, &head->futex_offset)) |
| 2459 | return; |
| 2460 | /* |
| 2461 | * Fetch any possibly pending lock-add first, and handle it |
| 2462 | * if it exists: |
| 2463 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2464 | if (fetch_robust_entry(&pending, &head->list_op_pending, &pip)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2465 | return; |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2466 | |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 2467 | next_entry = NULL; /* avoid warning with gcc */ |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2468 | while (entry != &head->list) { |
| 2469 | /* |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 2470 | * Fetch the next entry in the list before calling |
| 2471 | * handle_futex_death: |
| 2472 | */ |
| 2473 | rc = fetch_robust_entry(&next_entry, &entry->next, &next_pi); |
| 2474 | /* |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2475 | * A pending lock might already be on the list, so |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2476 | * don't process it twice: |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2477 | */ |
| 2478 | if (entry != pending) |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 2479 | if (handle_futex_death((void __user *)entry + futex_offset, |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 2480 | curr, pi)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2481 | return; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 2482 | if (rc) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2483 | return; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 2484 | entry = next_entry; |
| 2485 | pi = next_pi; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2486 | /* |
| 2487 | * Avoid excessively long or circular lists: |
| 2488 | */ |
| 2489 | if (!--limit) |
| 2490 | break; |
| 2491 | |
| 2492 | cond_resched(); |
| 2493 | } |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 2494 | |
| 2495 | if (pending) |
| 2496 | handle_futex_death((void __user *)pending + futex_offset, |
| 2497 | curr, pip); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 2498 | } |
| 2499 | |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2500 | long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 2501 | u32 __user *uaddr2, u32 val2, u32 val3) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2502 | { |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 2503 | int clockrt, ret = -ENOSYS; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2504 | int cmd = op & FUTEX_CMD_MASK; |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 2505 | int fshared = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2506 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2507 | if (!(op & FUTEX_PRIVATE_FLAG)) |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 2508 | fshared = 1; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2509 | |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 2510 | clockrt = op & FUTEX_CLOCK_REALTIME; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2511 | if (clockrt && cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI) |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 2512 | return -ENOSYS; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2513 | |
| 2514 | switch (cmd) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2515 | case FUTEX_WAIT: |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 2516 | val3 = FUTEX_BITSET_MATCH_ANY; |
| 2517 | case FUTEX_WAIT_BITSET: |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 2518 | ret = futex_wait(uaddr, fshared, val, timeout, val3, clockrt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2519 | break; |
| 2520 | case FUTEX_WAKE: |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 2521 | val3 = FUTEX_BITSET_MATCH_ANY; |
| 2522 | case FUTEX_WAKE_BITSET: |
| 2523 | ret = futex_wake(uaddr, fshared, val, val3); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2524 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2525 | case FUTEX_REQUEUE: |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2526 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2527 | break; |
| 2528 | case FUTEX_CMP_REQUEUE: |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2529 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3, |
| 2530 | 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2531 | break; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 2532 | case FUTEX_WAKE_OP: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2533 | ret = futex_wake_op(uaddr, fshared, uaddr2, val, val2, val3); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 2534 | break; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2535 | case FUTEX_LOCK_PI: |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2536 | if (futex_cmpxchg_enabled) |
| 2537 | ret = futex_lock_pi(uaddr, fshared, val, timeout, 0); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2538 | break; |
| 2539 | case FUTEX_UNLOCK_PI: |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2540 | if (futex_cmpxchg_enabled) |
| 2541 | ret = futex_unlock_pi(uaddr, fshared); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2542 | break; |
| 2543 | case FUTEX_TRYLOCK_PI: |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2544 | if (futex_cmpxchg_enabled) |
| 2545 | ret = futex_lock_pi(uaddr, fshared, 0, timeout, 1); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2546 | break; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2547 | case FUTEX_WAIT_REQUEUE_PI: |
| 2548 | val3 = FUTEX_BITSET_MATCH_ANY; |
| 2549 | ret = futex_wait_requeue_pi(uaddr, fshared, val, timeout, val3, |
| 2550 | clockrt, uaddr2); |
| 2551 | break; |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2552 | case FUTEX_CMP_REQUEUE_PI: |
| 2553 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3, |
| 2554 | 1); |
| 2555 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2556 | default: |
| 2557 | ret = -ENOSYS; |
| 2558 | } |
| 2559 | return ret; |
| 2560 | } |
| 2561 | |
| 2562 | |
Heiko Carstens | 17da2bd | 2009-01-14 14:14:10 +0100 | [diff] [blame] | 2563 | SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, |
| 2564 | struct timespec __user *, utime, u32 __user *, uaddr2, |
| 2565 | u32, val3) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2566 | { |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2567 | struct timespec ts; |
| 2568 | ktime_t t, *tp = NULL; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 2569 | u32 val2 = 0; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2570 | int cmd = op & FUTEX_CMD_MASK; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2571 | |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 2572 | if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2573 | cmd == FUTEX_WAIT_BITSET || |
| 2574 | cmd == FUTEX_WAIT_REQUEUE_PI)) { |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2575 | if (copy_from_user(&ts, utime, sizeof(ts)) != 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2576 | return -EFAULT; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2577 | if (!timespec_valid(&ts)) |
Thomas Gleixner | 9741ef96 | 2006-03-31 02:31:32 -0800 | [diff] [blame] | 2578 | return -EINVAL; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2579 | |
| 2580 | t = timespec_to_ktime(ts); |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2581 | if (cmd == FUTEX_WAIT) |
Thomas Gleixner | 5a7780e | 2008-02-13 09:20:43 +0100 | [diff] [blame] | 2582 | t = ktime_add_safe(ktime_get(), t); |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2583 | tp = &t; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2584 | } |
| 2585 | /* |
Darren Hart | 52400ba | 2009-04-03 13:40:49 -0700 | [diff] [blame] | 2586 | * requeue parameter in 'utime' if cmd == FUTEX_*_REQUEUE_*. |
Andreas Schwab | f54f098 | 2007-07-31 00:38:51 -0700 | [diff] [blame] | 2587 | * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2588 | */ |
Andreas Schwab | f54f098 | 2007-07-31 00:38:51 -0700 | [diff] [blame] | 2589 | if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
Darren Hart | ba9c22f | 2009-04-20 22:22:22 -0700 | [diff] [blame] | 2590 | cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 2591 | val2 = (u32) (unsigned long) utime; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2592 | |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2593 | return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2594 | } |
| 2595 | |
Benjamin Herrenschmidt | f6d107f | 2008-03-27 14:52:15 +1100 | [diff] [blame] | 2596 | static int __init futex_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2597 | { |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2598 | u32 curval; |
Thomas Gleixner | 3e4ab74 | 2008-02-23 15:23:55 -0800 | [diff] [blame] | 2599 | int i; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2600 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2601 | /* |
| 2602 | * This will fail and we want it. Some arch implementations do |
| 2603 | * runtime detection of the futex_atomic_cmpxchg_inatomic() |
| 2604 | * functionality. We want to know that before we call in any |
| 2605 | * of the complex code paths. Also we want to prevent |
| 2606 | * registration of robust lists in that case. NULL is |
| 2607 | * guaranteed to fault and we get -EFAULT on functional |
| 2608 | * implementation, the non functional ones will return |
| 2609 | * -ENOSYS. |
| 2610 | */ |
| 2611 | curval = cmpxchg_futex_value_locked(NULL, 0, 0); |
| 2612 | if (curval == -EFAULT) |
| 2613 | futex_cmpxchg_enabled = 1; |
| 2614 | |
Thomas Gleixner | 3e4ab74 | 2008-02-23 15:23:55 -0800 | [diff] [blame] | 2615 | for (i = 0; i < ARRAY_SIZE(futex_queues); i++) { |
| 2616 | plist_head_init(&futex_queues[i].chain, &futex_queues[i].lock); |
| 2617 | spin_lock_init(&futex_queues[i].lock); |
| 2618 | } |
| 2619 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2620 | return 0; |
| 2621 | } |
Benjamin Herrenschmidt | f6d107f | 2008-03-27 14:52:15 +1100 | [diff] [blame] | 2622 | __initcall(futex_init); |