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 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 22 | * Thanks to Ben LaHaise for yelling "hashed waitqueues" loudly |
| 23 | * enough at me, Linus for the original (flawed) idea, Matthew |
| 24 | * Kirkwood for proof-of-concept implementation. |
| 25 | * |
| 26 | * "The futexes are also cursed." |
| 27 | * "But they come in a choice of three flavours!" |
| 28 | * |
| 29 | * This program is free software; you can redistribute it and/or modify |
| 30 | * it under the terms of the GNU General Public License as published by |
| 31 | * the Free Software Foundation; either version 2 of the License, or |
| 32 | * (at your option) any later version. |
| 33 | * |
| 34 | * This program is distributed in the hope that it will be useful, |
| 35 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 36 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 37 | * GNU General Public License for more details. |
| 38 | * |
| 39 | * You should have received a copy of the GNU General Public License |
| 40 | * along with this program; if not, write to the Free Software |
| 41 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 42 | */ |
| 43 | #include <linux/slab.h> |
| 44 | #include <linux/poll.h> |
| 45 | #include <linux/fs.h> |
| 46 | #include <linux/file.h> |
| 47 | #include <linux/jhash.h> |
| 48 | #include <linux/init.h> |
| 49 | #include <linux/futex.h> |
| 50 | #include <linux/mount.h> |
| 51 | #include <linux/pagemap.h> |
| 52 | #include <linux/syscalls.h> |
Jesper Juhl | 7ed20e1 | 2005-05-01 08:59:14 -0700 | [diff] [blame] | 53 | #include <linux/signal.h> |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 54 | #include <linux/module.h> |
Andrey Mirkin | fd5eea4 | 2007-10-16 23:30:13 -0700 | [diff] [blame] | 55 | #include <linux/magic.h> |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 56 | #include <linux/pid.h> |
| 57 | #include <linux/nsproxy.h> |
| 58 | |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 59 | #include <asm/futex.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 60 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 61 | #include "rtmutex_common.h" |
| 62 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 63 | int __read_mostly futex_cmpxchg_enabled; |
| 64 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 65 | #define FUTEX_HASHBITS (CONFIG_BASE_SMALL ? 4 : 8) |
| 66 | |
| 67 | /* |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 68 | * Priority Inheritance state: |
| 69 | */ |
| 70 | struct futex_pi_state { |
| 71 | /* |
| 72 | * list of 'owned' pi_state instances - these have to be |
| 73 | * cleaned up in do_exit() if the task exits prematurely: |
| 74 | */ |
| 75 | struct list_head list; |
| 76 | |
| 77 | /* |
| 78 | * The PI object: |
| 79 | */ |
| 80 | struct rt_mutex pi_mutex; |
| 81 | |
| 82 | struct task_struct *owner; |
| 83 | atomic_t refcount; |
| 84 | |
| 85 | union futex_key key; |
| 86 | }; |
| 87 | |
| 88 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 89 | * We use this hashed waitqueue instead of a normal wait_queue_t, so |
| 90 | * we can wake only the relevant ones (hashed queues may be shared). |
| 91 | * |
| 92 | * A futex_q has a woken state, just like tasks have TASK_RUNNING. |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 93 | * 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] | 94 | * 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] | 95 | * wake up q->waiter, then make the second condition true. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | */ |
| 97 | struct futex_q { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 98 | struct plist_node list; |
Darren Hart | 73500ac | 2008-12-17 17:29:56 -0800 | [diff] [blame] | 99 | /* There can only be a single waiter */ |
| 100 | wait_queue_head_t waiter; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 102 | /* Which hash list lock to use: */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 103 | spinlock_t *lock_ptr; |
| 104 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 105 | /* Key which the futex is hashed on: */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 106 | union futex_key key; |
| 107 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 108 | /* Optional priority inheritance state: */ |
| 109 | struct futex_pi_state *pi_state; |
| 110 | struct task_struct *task; |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 111 | |
| 112 | /* Bitset for the optional bitmasked wakeup */ |
| 113 | u32 bitset; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | }; |
| 115 | |
| 116 | /* |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 117 | * Hash buckets are shared by all the futex_keys that hash to the same |
| 118 | * location. Each key may have multiple futex_q structures, one for each task |
| 119 | * waiting on a futex. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 120 | */ |
| 121 | struct futex_hash_bucket { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 122 | spinlock_t lock; |
| 123 | struct plist_head chain; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 124 | }; |
| 125 | |
| 126 | static struct futex_hash_bucket futex_queues[1<<FUTEX_HASHBITS]; |
| 127 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 128 | /* |
| 129 | * We hash on the keys returned from get_futex_key (see below). |
| 130 | */ |
| 131 | static struct futex_hash_bucket *hash_futex(union futex_key *key) |
| 132 | { |
| 133 | u32 hash = jhash2((u32*)&key->both.word, |
| 134 | (sizeof(key->both.word)+sizeof(key->both.ptr))/4, |
| 135 | key->both.offset); |
| 136 | return &futex_queues[hash & ((1 << FUTEX_HASHBITS)-1)]; |
| 137 | } |
| 138 | |
| 139 | /* |
| 140 | * Return 1 if two futex_keys are equal, 0 otherwise. |
| 141 | */ |
| 142 | static inline int match_futex(union futex_key *key1, union futex_key *key2) |
| 143 | { |
| 144 | return (key1->both.word == key2->both.word |
| 145 | && key1->both.ptr == key2->both.ptr |
| 146 | && key1->both.offset == key2->both.offset); |
| 147 | } |
| 148 | |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 149 | /* |
| 150 | * Take a reference to the resource addressed by a key. |
| 151 | * Can be called while holding spinlocks. |
| 152 | * |
| 153 | */ |
| 154 | static void get_futex_key_refs(union futex_key *key) |
| 155 | { |
| 156 | if (!key->both.ptr) |
| 157 | return; |
| 158 | |
| 159 | switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { |
| 160 | case FUT_OFF_INODE: |
| 161 | atomic_inc(&key->shared.inode->i_count); |
| 162 | break; |
| 163 | case FUT_OFF_MMSHARED: |
| 164 | atomic_inc(&key->private.mm->mm_count); |
| 165 | break; |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | /* |
| 170 | * Drop a reference to the resource addressed by a key. |
| 171 | * The hash bucket spinlock must not be held. |
| 172 | */ |
| 173 | static void drop_futex_key_refs(union futex_key *key) |
| 174 | { |
Darren Hart | 90621c4 | 2008-12-29 19:43:21 -0800 | [diff] [blame] | 175 | if (!key->both.ptr) { |
| 176 | /* If we're here then we tried to put a key we failed to get */ |
| 177 | WARN_ON_ONCE(1); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 178 | return; |
Darren Hart | 90621c4 | 2008-12-29 19:43:21 -0800 | [diff] [blame] | 179 | } |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 180 | |
| 181 | switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { |
| 182 | case FUT_OFF_INODE: |
| 183 | iput(key->shared.inode); |
| 184 | break; |
| 185 | case FUT_OFF_MMSHARED: |
| 186 | mmdrop(key->private.mm); |
| 187 | break; |
| 188 | } |
| 189 | } |
| 190 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 191 | /** |
| 192 | * get_futex_key - Get parameters which are the keys for a futex. |
| 193 | * @uaddr: virtual address of the futex |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 194 | * @fshared: 0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 195 | * @key: address where result is stored. |
| 196 | * |
| 197 | * Returns a negative error code or 0 |
| 198 | * The key words are stored in *key on success. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 199 | * |
Josef "Jeff" Sipek | f3a43f3 | 2006-12-08 02:36:43 -0800 | [diff] [blame] | 200 | * 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] | 201 | * offset_within_page). For private mappings, it's (uaddr, current->mm). |
| 202 | * We can usually work out the index without swapping in the page. |
| 203 | * |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 204 | * lock_page() might sleep, the caller should not hold a spinlock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 205 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 206 | static int get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 207 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 208 | unsigned long address = (unsigned long)uaddr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 209 | struct mm_struct *mm = current->mm; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 210 | struct page *page; |
| 211 | int err; |
| 212 | |
| 213 | /* |
| 214 | * The futex address must be "naturally" aligned. |
| 215 | */ |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 216 | key->both.offset = address % PAGE_SIZE; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 217 | if (unlikely((address % sizeof(u32)) != 0)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 218 | return -EINVAL; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 219 | address -= key->both.offset; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 220 | |
| 221 | /* |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 222 | * PROCESS_PRIVATE futexes are fast. |
| 223 | * As the mm cannot disappear under us and the 'key' only needs |
| 224 | * virtual address, we dont even have to find the underlying vma. |
| 225 | * Note : We do have to check 'uaddr' is a valid user address, |
| 226 | * but access_ok() should be faster than find_vma() |
| 227 | */ |
| 228 | if (!fshared) { |
| 229 | if (unlikely(!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))) |
| 230 | return -EFAULT; |
| 231 | key->private.mm = mm; |
| 232 | key->private.address = address; |
Peter Zijlstra | 42569c3 | 2008-09-30 12:33:07 +0200 | [diff] [blame] | 233 | get_futex_key_refs(key); |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 234 | return 0; |
| 235 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 236 | |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 237 | again: |
Peter Zijlstra | 734b05b | 2008-09-26 19:32:22 +0200 | [diff] [blame] | 238 | err = get_user_pages_fast(address, 1, 0, &page); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 239 | if (err < 0) |
| 240 | return err; |
| 241 | |
| 242 | lock_page(page); |
| 243 | if (!page->mapping) { |
| 244 | unlock_page(page); |
| 245 | put_page(page); |
| 246 | goto again; |
| 247 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 248 | |
| 249 | /* |
| 250 | * Private mappings are handled in a simple way. |
| 251 | * |
| 252 | * NOTE: When userspace waits on a MAP_SHARED mapping, even if |
| 253 | * 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] | 254 | * the object not the particular process. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 255 | */ |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 256 | if (PageAnon(page)) { |
| 257 | key->both.offset |= FUT_OFF_MMSHARED; /* ref taken on mm */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 258 | key->private.mm = mm; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 259 | key->private.address = address; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 260 | } else { |
| 261 | key->both.offset |= FUT_OFF_INODE; /* inode-based key */ |
| 262 | key->shared.inode = page->mapping->host; |
| 263 | key->shared.pgoff = page->index; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 264 | } |
| 265 | |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 266 | get_futex_key_refs(key); |
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 | unlock_page(page); |
| 269 | put_page(page); |
| 270 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 271 | } |
| 272 | |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 273 | static inline |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 274 | void put_futex_key(int fshared, union futex_key *key) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 275 | { |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 276 | drop_futex_key_refs(key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 277 | } |
| 278 | |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 279 | static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval) |
| 280 | { |
| 281 | u32 curval; |
| 282 | |
| 283 | pagefault_disable(); |
| 284 | curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval); |
| 285 | pagefault_enable(); |
| 286 | |
| 287 | return curval; |
| 288 | } |
| 289 | |
| 290 | static int get_futex_value_locked(u32 *dest, u32 __user *from) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 291 | { |
| 292 | int ret; |
| 293 | |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame] | 294 | pagefault_disable(); |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 295 | ret = __copy_from_user_inatomic(dest, from, sizeof(u32)); |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame] | 296 | pagefault_enable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 297 | |
| 298 | return ret ? -EFAULT : 0; |
| 299 | } |
| 300 | |
| 301 | /* |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 302 | * Fault handling. |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 303 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 304 | static int futex_handle_fault(unsigned long address, int attempt) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 305 | { |
| 306 | struct vm_area_struct * vma; |
| 307 | struct mm_struct *mm = current->mm; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 308 | int ret = -EFAULT; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 309 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 310 | if (attempt > 2) |
| 311 | return ret; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 312 | |
Peter Zijlstra | 6127070 | 2008-09-26 19:32:21 +0200 | [diff] [blame] | 313 | down_read(&mm->mmap_sem); |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 314 | vma = find_vma(mm, address); |
| 315 | if (vma && address >= vma->vm_start && |
| 316 | (vma->vm_flags & VM_WRITE)) { |
Nick Piggin | 83c5407 | 2007-07-19 01:47:05 -0700 | [diff] [blame] | 317 | int fault; |
| 318 | fault = handle_mm_fault(mm, vma, address, 1); |
| 319 | if (unlikely((fault & VM_FAULT_ERROR))) { |
| 320 | #if 0 |
| 321 | /* XXX: let's do this when we verify it is OK */ |
| 322 | if (ret & VM_FAULT_OOM) |
| 323 | ret = -ENOMEM; |
| 324 | #endif |
| 325 | } else { |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 326 | ret = 0; |
Nick Piggin | 83c5407 | 2007-07-19 01:47:05 -0700 | [diff] [blame] | 327 | if (fault & VM_FAULT_MAJOR) |
| 328 | current->maj_flt++; |
| 329 | else |
| 330 | current->min_flt++; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 331 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 332 | } |
Peter Zijlstra | 6127070 | 2008-09-26 19:32:21 +0200 | [diff] [blame] | 333 | up_read(&mm->mmap_sem); |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 334 | return ret; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 335 | } |
| 336 | |
| 337 | /* |
| 338 | * PI code: |
| 339 | */ |
| 340 | static int refill_pi_state_cache(void) |
| 341 | { |
| 342 | struct futex_pi_state *pi_state; |
| 343 | |
| 344 | if (likely(current->pi_state_cache)) |
| 345 | return 0; |
| 346 | |
Burman Yan | 4668edc | 2006-12-06 20:38:51 -0800 | [diff] [blame] | 347 | pi_state = kzalloc(sizeof(*pi_state), GFP_KERNEL); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 348 | |
| 349 | if (!pi_state) |
| 350 | return -ENOMEM; |
| 351 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 352 | INIT_LIST_HEAD(&pi_state->list); |
| 353 | /* pi_mutex gets initialized later */ |
| 354 | pi_state->owner = NULL; |
| 355 | atomic_set(&pi_state->refcount, 1); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 356 | pi_state->key = FUTEX_KEY_INIT; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 357 | |
| 358 | current->pi_state_cache = pi_state; |
| 359 | |
| 360 | return 0; |
| 361 | } |
| 362 | |
| 363 | static struct futex_pi_state * alloc_pi_state(void) |
| 364 | { |
| 365 | struct futex_pi_state *pi_state = current->pi_state_cache; |
| 366 | |
| 367 | WARN_ON(!pi_state); |
| 368 | current->pi_state_cache = NULL; |
| 369 | |
| 370 | return pi_state; |
| 371 | } |
| 372 | |
| 373 | static void free_pi_state(struct futex_pi_state *pi_state) |
| 374 | { |
| 375 | if (!atomic_dec_and_test(&pi_state->refcount)) |
| 376 | return; |
| 377 | |
| 378 | /* |
| 379 | * If pi_state->owner is NULL, the owner is most probably dying |
| 380 | * and has cleaned up the pi_state already |
| 381 | */ |
| 382 | if (pi_state->owner) { |
| 383 | spin_lock_irq(&pi_state->owner->pi_lock); |
| 384 | list_del_init(&pi_state->list); |
| 385 | spin_unlock_irq(&pi_state->owner->pi_lock); |
| 386 | |
| 387 | rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner); |
| 388 | } |
| 389 | |
| 390 | if (current->pi_state_cache) |
| 391 | kfree(pi_state); |
| 392 | else { |
| 393 | /* |
| 394 | * pi_state->list is already empty. |
| 395 | * clear pi_state->owner. |
| 396 | * refcount is at 0 - put it back to 1. |
| 397 | */ |
| 398 | pi_state->owner = NULL; |
| 399 | atomic_set(&pi_state->refcount, 1); |
| 400 | current->pi_state_cache = pi_state; |
| 401 | } |
| 402 | } |
| 403 | |
| 404 | /* |
| 405 | * Look up the task based on what TID userspace gave us. |
| 406 | * We dont trust it. |
| 407 | */ |
| 408 | static struct task_struct * futex_find_get_task(pid_t pid) |
| 409 | { |
| 410 | struct task_struct *p; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 411 | const struct cred *cred = current_cred(), *pcred; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 412 | |
Oleg Nesterov | d359b54 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 413 | rcu_read_lock(); |
Pavel Emelyanov | 228ebcb | 2007-10-18 23:40:16 -0700 | [diff] [blame] | 414 | p = find_task_by_vpid(pid); |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 415 | if (!p) { |
Thomas Gleixner | a06381f | 2007-06-23 11:48:40 +0200 | [diff] [blame] | 416 | p = ERR_PTR(-ESRCH); |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 417 | } else { |
| 418 | pcred = __task_cred(p); |
| 419 | if (cred->euid != pcred->euid && |
| 420 | cred->euid != pcred->uid) |
| 421 | p = ERR_PTR(-ESRCH); |
| 422 | else |
| 423 | get_task_struct(p); |
| 424 | } |
Thomas Gleixner | a06381f | 2007-06-23 11:48:40 +0200 | [diff] [blame] | 425 | |
Oleg Nesterov | d359b54 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 426 | rcu_read_unlock(); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 427 | |
| 428 | return p; |
| 429 | } |
| 430 | |
| 431 | /* |
| 432 | * This task is holding PI mutexes at exit time => bad. |
| 433 | * Kernel cleans up PI-state, but userspace is likely hosed. |
| 434 | * (Robust-futex cleanup is separate and might save the day for userspace.) |
| 435 | */ |
| 436 | void exit_pi_state_list(struct task_struct *curr) |
| 437 | { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 438 | struct list_head *next, *head = &curr->pi_state_list; |
| 439 | struct futex_pi_state *pi_state; |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 440 | struct futex_hash_bucket *hb; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 441 | union futex_key key = FUTEX_KEY_INIT; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 442 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 443 | if (!futex_cmpxchg_enabled) |
| 444 | return; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 445 | /* |
| 446 | * We are a ZOMBIE and nobody can enqueue itself on |
| 447 | * pi_state_list anymore, but we have to be careful |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 448 | * versus waiters unqueueing themselves: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 449 | */ |
| 450 | spin_lock_irq(&curr->pi_lock); |
| 451 | while (!list_empty(head)) { |
| 452 | |
| 453 | next = head->next; |
| 454 | pi_state = list_entry(next, struct futex_pi_state, list); |
| 455 | key = pi_state->key; |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 456 | hb = hash_futex(&key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 457 | spin_unlock_irq(&curr->pi_lock); |
| 458 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 459 | spin_lock(&hb->lock); |
| 460 | |
| 461 | spin_lock_irq(&curr->pi_lock); |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 462 | /* |
| 463 | * We dropped the pi-lock, so re-check whether this |
| 464 | * task still owns the PI-state: |
| 465 | */ |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 466 | if (head->next != next) { |
| 467 | spin_unlock(&hb->lock); |
| 468 | continue; |
| 469 | } |
| 470 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 471 | WARN_ON(pi_state->owner != curr); |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 472 | WARN_ON(list_empty(&pi_state->list)); |
| 473 | list_del_init(&pi_state->list); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 474 | pi_state->owner = NULL; |
| 475 | spin_unlock_irq(&curr->pi_lock); |
| 476 | |
| 477 | rt_mutex_unlock(&pi_state->pi_mutex); |
| 478 | |
| 479 | spin_unlock(&hb->lock); |
| 480 | |
| 481 | spin_lock_irq(&curr->pi_lock); |
| 482 | } |
| 483 | spin_unlock_irq(&curr->pi_lock); |
| 484 | } |
| 485 | |
| 486 | static int |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 487 | lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, |
| 488 | union futex_key *key, struct futex_pi_state **ps) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 489 | { |
| 490 | struct futex_pi_state *pi_state = NULL; |
| 491 | struct futex_q *this, *next; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 492 | struct plist_head *head; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 493 | struct task_struct *p; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 494 | pid_t pid = uval & FUTEX_TID_MASK; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 495 | |
| 496 | head = &hb->chain; |
| 497 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 498 | plist_for_each_entry_safe(this, next, head, list) { |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 499 | if (match_futex(&this->key, key)) { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 500 | /* |
| 501 | * Another waiter already exists - bump up |
| 502 | * the refcount and return its pi_state: |
| 503 | */ |
| 504 | pi_state = this->pi_state; |
Thomas Gleixner | 06a9ec2 | 2006-07-10 04:44:30 -0700 | [diff] [blame] | 505 | /* |
| 506 | * Userspace might have messed up non PI and PI futexes |
| 507 | */ |
| 508 | if (unlikely(!pi_state)) |
| 509 | return -EINVAL; |
| 510 | |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 511 | WARN_ON(!atomic_read(&pi_state->refcount)); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 512 | WARN_ON(pid && pi_state->owner && |
| 513 | pi_state->owner->pid != pid); |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 514 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 515 | atomic_inc(&pi_state->refcount); |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 516 | *ps = pi_state; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 517 | |
| 518 | return 0; |
| 519 | } |
| 520 | } |
| 521 | |
| 522 | /* |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 523 | * 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] | 524 | * the new pi_state to it, but bail out when TID = 0 |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 525 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 526 | if (!pid) |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 527 | return -ESRCH; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 528 | p = futex_find_get_task(pid); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 529 | if (IS_ERR(p)) |
| 530 | return PTR_ERR(p); |
| 531 | |
| 532 | /* |
| 533 | * We need to look at the task state flags to figure out, |
| 534 | * whether the task is exiting. To protect against the do_exit |
| 535 | * change of the task flags, we do this protected by |
| 536 | * p->pi_lock: |
| 537 | */ |
| 538 | spin_lock_irq(&p->pi_lock); |
| 539 | if (unlikely(p->flags & PF_EXITING)) { |
| 540 | /* |
| 541 | * The task is on the way out. When PF_EXITPIDONE is |
| 542 | * set, we know that the task has finished the |
| 543 | * cleanup: |
| 544 | */ |
| 545 | int ret = (p->flags & PF_EXITPIDONE) ? -ESRCH : -EAGAIN; |
| 546 | |
| 547 | spin_unlock_irq(&p->pi_lock); |
| 548 | put_task_struct(p); |
| 549 | return ret; |
| 550 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 551 | |
| 552 | pi_state = alloc_pi_state(); |
| 553 | |
| 554 | /* |
| 555 | * Initialize the pi_mutex in locked state and make 'p' |
| 556 | * the owner of it: |
| 557 | */ |
| 558 | rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p); |
| 559 | |
| 560 | /* Store the key for possible exit cleanups: */ |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 561 | pi_state->key = *key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 562 | |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 563 | WARN_ON(!list_empty(&pi_state->list)); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 564 | list_add(&pi_state->list, &p->pi_state_list); |
| 565 | pi_state->owner = p; |
| 566 | spin_unlock_irq(&p->pi_lock); |
| 567 | |
| 568 | put_task_struct(p); |
| 569 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 570 | *ps = pi_state; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 571 | |
| 572 | return 0; |
| 573 | } |
| 574 | |
| 575 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 576 | * The hash bucket lock must be held when this is called. |
| 577 | * Afterwards, the futex_q must not be accessed. |
| 578 | */ |
| 579 | static void wake_futex(struct futex_q *q) |
| 580 | { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 581 | plist_del(&q->list, &q->list.plist); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 582 | /* |
| 583 | * The lock in wake_up_all() is a crucial memory barrier after the |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 584 | * plist_del() and also before assigning to q->lock_ptr. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 585 | */ |
Darren Hart | 73500ac | 2008-12-17 17:29:56 -0800 | [diff] [blame] | 586 | wake_up(&q->waiter); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 587 | /* |
| 588 | * The waiting task can free the futex_q as soon as this is written, |
| 589 | * without taking any locks. This must come last. |
Andrew Morton | 8e31108 | 2005-12-23 19:54:46 -0800 | [diff] [blame] | 590 | * |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 591 | * A memory barrier is required here to prevent the following store to |
| 592 | * lock_ptr from getting ahead of the wakeup. Clearing the lock at the |
| 593 | * end of wake_up() does not prevent this store from moving. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 594 | */ |
Ralf Baechle | ccdea2f | 2006-12-06 20:40:26 -0800 | [diff] [blame] | 595 | smp_wmb(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 596 | q->lock_ptr = NULL; |
| 597 | } |
| 598 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 599 | static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this) |
| 600 | { |
| 601 | struct task_struct *new_owner; |
| 602 | struct futex_pi_state *pi_state = this->pi_state; |
| 603 | u32 curval, newval; |
| 604 | |
| 605 | if (!pi_state) |
| 606 | return -EINVAL; |
| 607 | |
Ingo Molnar | 21778867 | 2007-03-16 13:38:31 -0800 | [diff] [blame] | 608 | spin_lock(&pi_state->pi_mutex.wait_lock); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 609 | new_owner = rt_mutex_next_owner(&pi_state->pi_mutex); |
| 610 | |
| 611 | /* |
| 612 | * This happens when we have stolen the lock and the original |
| 613 | * pending owner did not enqueue itself back on the rt_mutex. |
| 614 | * Thats not a tragedy. We know that way, that a lock waiter |
| 615 | * is on the fly. We make the futex_q waiter the pending owner. |
| 616 | */ |
| 617 | if (!new_owner) |
| 618 | new_owner = this->task; |
| 619 | |
| 620 | /* |
| 621 | * We pass it to the next owner. (The WAITERS bit is always |
| 622 | * kept enabled while there is PI state around. We must also |
| 623 | * preserve the owner died bit.) |
| 624 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 625 | if (!(uval & FUTEX_OWNER_DIED)) { |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 626 | int ret = 0; |
| 627 | |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 628 | newval = FUTEX_WAITERS | task_pid_vnr(new_owner); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 629 | |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 630 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 631 | |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 632 | if (curval == -EFAULT) |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 633 | ret = -EFAULT; |
Thomas Gleixner | cde898f | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 634 | else if (curval != uval) |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 635 | ret = -EINVAL; |
| 636 | if (ret) { |
| 637 | spin_unlock(&pi_state->pi_mutex.wait_lock); |
| 638 | return ret; |
| 639 | } |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 640 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 641 | |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 642 | spin_lock_irq(&pi_state->owner->pi_lock); |
| 643 | WARN_ON(list_empty(&pi_state->list)); |
| 644 | list_del_init(&pi_state->list); |
| 645 | spin_unlock_irq(&pi_state->owner->pi_lock); |
| 646 | |
| 647 | spin_lock_irq(&new_owner->pi_lock); |
| 648 | WARN_ON(!list_empty(&pi_state->list)); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 649 | list_add(&pi_state->list, &new_owner->pi_state_list); |
| 650 | pi_state->owner = new_owner; |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 651 | spin_unlock_irq(&new_owner->pi_lock); |
| 652 | |
Ingo Molnar | 21778867 | 2007-03-16 13:38:31 -0800 | [diff] [blame] | 653 | spin_unlock(&pi_state->pi_mutex.wait_lock); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 654 | rt_mutex_unlock(&pi_state->pi_mutex); |
| 655 | |
| 656 | return 0; |
| 657 | } |
| 658 | |
| 659 | static int unlock_futex_pi(u32 __user *uaddr, u32 uval) |
| 660 | { |
| 661 | u32 oldval; |
| 662 | |
| 663 | /* |
| 664 | * There is no waiter, so we unlock the futex. The owner died |
| 665 | * bit has not to be preserved here. We are the owner: |
| 666 | */ |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 667 | oldval = cmpxchg_futex_value_locked(uaddr, uval, 0); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 668 | |
| 669 | if (oldval == -EFAULT) |
| 670 | return oldval; |
| 671 | if (oldval != uval) |
| 672 | return -EAGAIN; |
| 673 | |
| 674 | return 0; |
| 675 | } |
| 676 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 677 | /* |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 678 | * Express the locking dependencies for lockdep: |
| 679 | */ |
| 680 | static inline void |
| 681 | double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) |
| 682 | { |
| 683 | if (hb1 <= hb2) { |
| 684 | spin_lock(&hb1->lock); |
| 685 | if (hb1 < hb2) |
| 686 | spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); |
| 687 | } else { /* hb1 > hb2 */ |
| 688 | spin_lock(&hb2->lock); |
| 689 | spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); |
| 690 | } |
| 691 | } |
| 692 | |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 693 | static inline void |
| 694 | double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) |
| 695 | { |
| 696 | if (hb1 <= hb2) { |
| 697 | spin_unlock(&hb2->lock); |
| 698 | if (hb1 < hb2) |
| 699 | spin_unlock(&hb1->lock); |
| 700 | } else { /* hb1 > hb2 */ |
| 701 | spin_unlock(&hb1->lock); |
| 702 | spin_unlock(&hb2->lock); |
| 703 | } |
| 704 | } |
| 705 | |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 706 | /* |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 707 | * Wake up waiters matching bitset queued on this futex (uaddr). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 708 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 709 | 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] | 710 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 711 | struct futex_hash_bucket *hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 712 | struct futex_q *this, *next; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 713 | struct plist_head *head; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 714 | union futex_key key = FUTEX_KEY_INIT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 715 | int ret; |
| 716 | |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 717 | if (!bitset) |
| 718 | return -EINVAL; |
| 719 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 720 | ret = get_futex_key(uaddr, fshared, &key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 721 | if (unlikely(ret != 0)) |
| 722 | goto out; |
| 723 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 724 | hb = hash_futex(&key); |
| 725 | spin_lock(&hb->lock); |
| 726 | head = &hb->chain; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 727 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 728 | plist_for_each_entry_safe(this, next, head, list) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 729 | if (match_futex (&this->key, &key)) { |
Ingo Molnar | ed6f7b1 | 2006-07-01 04:35:46 -0700 | [diff] [blame] | 730 | if (this->pi_state) { |
| 731 | ret = -EINVAL; |
| 732 | break; |
| 733 | } |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 734 | |
| 735 | /* Check if one of the bits is set in both bitsets */ |
| 736 | if (!(this->bitset & bitset)) |
| 737 | continue; |
| 738 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 739 | wake_futex(this); |
| 740 | if (++ret >= nr_wake) |
| 741 | break; |
| 742 | } |
| 743 | } |
| 744 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 745 | spin_unlock(&hb->lock); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 746 | put_futex_key(fshared, &key); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 747 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 748 | return ret; |
| 749 | } |
| 750 | |
| 751 | /* |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 752 | * Wake up all waiters hashed on the physical page that is mapped |
| 753 | * to this virtual address: |
| 754 | */ |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 755 | static int |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 756 | futex_wake_op(u32 __user *uaddr1, int fshared, u32 __user *uaddr2, |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 757 | int nr_wake, int nr_wake2, int op) |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 758 | { |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 759 | union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 760 | struct futex_hash_bucket *hb1, *hb2; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 761 | struct plist_head *head; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 762 | struct futex_q *this, *next; |
| 763 | int ret, op_ret, attempt = 0; |
| 764 | |
| 765 | retryfull: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 766 | ret = get_futex_key(uaddr1, fshared, &key1); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 767 | if (unlikely(ret != 0)) |
| 768 | goto out; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 769 | ret = get_futex_key(uaddr2, fshared, &key2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 770 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 771 | goto out_put_key1; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 772 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 773 | hb1 = hash_futex(&key1); |
| 774 | hb2 = hash_futex(&key2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 775 | |
| 776 | retry: |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 777 | double_lock_hb(hb1, hb2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 778 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 779 | op_ret = futex_atomic_op_inuser(op, uaddr2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 780 | if (unlikely(op_ret < 0)) { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 781 | u32 dummy; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 782 | |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 783 | double_unlock_hb(hb1, hb2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 784 | |
David Howells | 7ee1dd3 | 2006-01-06 00:11:44 -0800 | [diff] [blame] | 785 | #ifndef CONFIG_MMU |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 786 | /* |
| 787 | * we don't get EFAULT from MMU faults if we don't have an MMU, |
| 788 | * but we might get them from range checking |
| 789 | */ |
David Howells | 7ee1dd3 | 2006-01-06 00:11:44 -0800 | [diff] [blame] | 790 | ret = op_ret; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 791 | goto out_put_keys; |
David Howells | 7ee1dd3 | 2006-01-06 00:11:44 -0800 | [diff] [blame] | 792 | #endif |
| 793 | |
David Gibson | 796f8d9 | 2005-11-07 00:59:33 -0800 | [diff] [blame] | 794 | if (unlikely(op_ret != -EFAULT)) { |
| 795 | ret = op_ret; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 796 | goto out_put_keys; |
David Gibson | 796f8d9 | 2005-11-07 00:59:33 -0800 | [diff] [blame] | 797 | } |
| 798 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 799 | /* |
| 800 | * futex_atomic_op_inuser needs to both read and write |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 801 | * *(int __user *)uaddr2, but we can't modify it |
| 802 | * non-atomically. Therefore, if get_user below is not |
| 803 | * enough, we need to handle the fault ourselves, while |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 804 | * still holding the mmap_sem. |
| 805 | */ |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 806 | if (attempt++) { |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 807 | ret = futex_handle_fault((unsigned long)uaddr2, |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 808 | attempt); |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 809 | if (ret) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 810 | goto out_put_keys; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 811 | goto retry; |
| 812 | } |
| 813 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 814 | ret = get_user(dummy, uaddr2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 815 | if (ret) |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 816 | goto out_put_keys; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 817 | |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 818 | put_futex_key(fshared, &key2); |
| 819 | put_futex_key(fshared, &key1); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 820 | goto retryfull; |
| 821 | } |
| 822 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 823 | head = &hb1->chain; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 824 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 825 | plist_for_each_entry_safe(this, next, head, list) { |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 826 | if (match_futex (&this->key, &key1)) { |
| 827 | wake_futex(this); |
| 828 | if (++ret >= nr_wake) |
| 829 | break; |
| 830 | } |
| 831 | } |
| 832 | |
| 833 | if (op_ret > 0) { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 834 | head = &hb2->chain; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 835 | |
| 836 | op_ret = 0; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 837 | plist_for_each_entry_safe(this, next, head, list) { |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 838 | if (match_futex (&this->key, &key2)) { |
| 839 | wake_futex(this); |
| 840 | if (++op_ret >= nr_wake2) |
| 841 | break; |
| 842 | } |
| 843 | } |
| 844 | ret += op_ret; |
| 845 | } |
| 846 | |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 847 | double_unlock_hb(hb1, hb2); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 848 | out_put_keys: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 849 | put_futex_key(fshared, &key2); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 850 | out_put_key1: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 851 | put_futex_key(fshared, &key1); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 852 | out: |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 853 | return ret; |
| 854 | } |
| 855 | |
| 856 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 857 | * Requeue all waiters hashed on one physical page to another |
| 858 | * physical page. |
| 859 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 860 | static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2, |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 861 | int nr_wake, int nr_requeue, u32 *cmpval) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 862 | { |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 863 | union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 864 | struct futex_hash_bucket *hb1, *hb2; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 865 | struct plist_head *head1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 866 | struct futex_q *this, *next; |
| 867 | int ret, drop_count = 0; |
| 868 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 869 | retry: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 870 | ret = get_futex_key(uaddr1, fshared, &key1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 871 | if (unlikely(ret != 0)) |
| 872 | goto out; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 873 | ret = get_futex_key(uaddr2, fshared, &key2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 874 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 875 | goto out_put_key1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 876 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 877 | hb1 = hash_futex(&key1); |
| 878 | hb2 = hash_futex(&key2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 879 | |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 880 | double_lock_hb(hb1, hb2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 881 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 882 | if (likely(cmpval != NULL)) { |
| 883 | u32 curval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 884 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 885 | ret = get_futex_value_locked(&curval, uaddr1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 886 | |
| 887 | if (unlikely(ret)) { |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 888 | double_unlock_hb(hb1, hb2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 889 | |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 890 | put_futex_key(fshared, &key2); |
| 891 | put_futex_key(fshared, &key1); |
| 892 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 893 | ret = get_user(curval, uaddr1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 894 | |
| 895 | if (!ret) |
| 896 | goto retry; |
| 897 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 898 | goto out_put_keys; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 899 | } |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 900 | if (curval != *cmpval) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 901 | ret = -EAGAIN; |
| 902 | goto out_unlock; |
| 903 | } |
| 904 | } |
| 905 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 906 | head1 = &hb1->chain; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 907 | plist_for_each_entry_safe(this, next, head1, list) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 908 | if (!match_futex (&this->key, &key1)) |
| 909 | continue; |
| 910 | if (++ret <= nr_wake) { |
| 911 | wake_futex(this); |
| 912 | } else { |
Sebastien Dugue | 59e0e0a | 2006-06-27 02:55:03 -0700 | [diff] [blame] | 913 | /* |
| 914 | * If key1 and key2 hash to the same bucket, no need to |
| 915 | * requeue. |
| 916 | */ |
| 917 | if (likely(head1 != &hb2->chain)) { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 918 | plist_del(&this->list, &hb1->chain); |
| 919 | plist_add(&this->list, &hb2->chain); |
Sebastien Dugue | 59e0e0a | 2006-06-27 02:55:03 -0700 | [diff] [blame] | 920 | this->lock_ptr = &hb2->lock; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 921 | #ifdef CONFIG_DEBUG_PI_LIST |
| 922 | this->list.plist.lock = &hb2->lock; |
| 923 | #endif |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 924 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 925 | this->key = key2; |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 926 | get_futex_key_refs(&key2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 927 | drop_count++; |
| 928 | |
| 929 | if (ret - nr_wake >= nr_requeue) |
| 930 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 931 | } |
| 932 | } |
| 933 | |
| 934 | out_unlock: |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 935 | double_unlock_hb(hb1, hb2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 936 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 937 | /* drop_futex_key_refs() must be called outside the spinlocks. */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 938 | while (--drop_count >= 0) |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 939 | drop_futex_key_refs(&key1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 940 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 941 | out_put_keys: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 942 | put_futex_key(fshared, &key2); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 943 | out_put_key1: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 944 | put_futex_key(fshared, &key1); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 945 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 946 | return ret; |
| 947 | } |
| 948 | |
| 949 | /* The key must be already stored in q->key. */ |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 950 | static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 951 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 952 | struct futex_hash_bucket *hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 953 | |
Darren Hart | 73500ac | 2008-12-17 17:29:56 -0800 | [diff] [blame] | 954 | init_waitqueue_head(&q->waiter); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 955 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 956 | get_futex_key_refs(&q->key); |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 957 | hb = hash_futex(&q->key); |
| 958 | q->lock_ptr = &hb->lock; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 959 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 960 | spin_lock(&hb->lock); |
| 961 | return hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 962 | } |
| 963 | |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 964 | 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] | 965 | { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 966 | int prio; |
| 967 | |
| 968 | /* |
| 969 | * The priority used to register this element is |
| 970 | * - either the real thread-priority for the real-time threads |
| 971 | * (i.e. threads with a priority lower than MAX_RT_PRIO) |
| 972 | * - or MAX_RT_PRIO for non-RT threads. |
| 973 | * Thus, all RT-threads are woken first in priority order, and |
| 974 | * the others are woken last, in FIFO order. |
| 975 | */ |
| 976 | prio = min(current->normal_prio, MAX_RT_PRIO); |
| 977 | |
| 978 | plist_node_init(&q->list, prio); |
| 979 | #ifdef CONFIG_DEBUG_PI_LIST |
| 980 | q->list.plist.lock = &hb->lock; |
| 981 | #endif |
| 982 | plist_add(&q->list, &hb->chain); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 983 | q->task = current; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 984 | spin_unlock(&hb->lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 985 | } |
| 986 | |
| 987 | static inline void |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 988 | queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 989 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 990 | spin_unlock(&hb->lock); |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 991 | drop_futex_key_refs(&q->key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 992 | } |
| 993 | |
| 994 | /* |
| 995 | * queue_me and unqueue_me must be called as a pair, each |
| 996 | * exactly once. They are called with the hashed spinlock held. |
| 997 | */ |
| 998 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 999 | /* Return 1 if we were still queued (ie. 0 means we were woken) */ |
| 1000 | static int unqueue_me(struct futex_q *q) |
| 1001 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1002 | spinlock_t *lock_ptr; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1003 | int ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1004 | |
| 1005 | /* 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] | 1006 | retry: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1007 | lock_ptr = q->lock_ptr; |
Christian Borntraeger | e91467e | 2006-08-05 12:13:52 -0700 | [diff] [blame] | 1008 | barrier(); |
Stephen Hemminger | c80544d | 2007-10-18 03:07:05 -0700 | [diff] [blame] | 1009 | if (lock_ptr != NULL) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1010 | spin_lock(lock_ptr); |
| 1011 | /* |
| 1012 | * q->lock_ptr can change between reading it and |
| 1013 | * spin_lock(), causing us to take the wrong lock. This |
| 1014 | * corrects the race condition. |
| 1015 | * |
| 1016 | * Reasoning goes like this: if we have the wrong lock, |
| 1017 | * q->lock_ptr must have changed (maybe several times) |
| 1018 | * between reading it and the spin_lock(). It can |
| 1019 | * change again after the spin_lock() but only if it was |
| 1020 | * already changed before the spin_lock(). It cannot, |
| 1021 | * however, change back to the original value. Therefore |
| 1022 | * we can detect whether we acquired the correct lock. |
| 1023 | */ |
| 1024 | if (unlikely(lock_ptr != q->lock_ptr)) { |
| 1025 | spin_unlock(lock_ptr); |
| 1026 | goto retry; |
| 1027 | } |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1028 | WARN_ON(plist_node_empty(&q->list)); |
| 1029 | plist_del(&q->list, &q->list.plist); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1030 | |
| 1031 | BUG_ON(q->pi_state); |
| 1032 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1033 | spin_unlock(lock_ptr); |
| 1034 | ret = 1; |
| 1035 | } |
| 1036 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1037 | drop_futex_key_refs(&q->key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1038 | return ret; |
| 1039 | } |
| 1040 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1041 | /* |
| 1042 | * PI futexes can not be requeued and must remove themself from the |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1043 | * hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry |
| 1044 | * and dropped here. |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1045 | */ |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1046 | static void unqueue_me_pi(struct futex_q *q) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1047 | { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1048 | WARN_ON(plist_node_empty(&q->list)); |
| 1049 | plist_del(&q->list, &q->list.plist); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1050 | |
| 1051 | BUG_ON(!q->pi_state); |
| 1052 | free_pi_state(q->pi_state); |
| 1053 | q->pi_state = NULL; |
| 1054 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1055 | spin_unlock(q->lock_ptr); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1056 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1057 | drop_futex_key_refs(&q->key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1058 | } |
| 1059 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1060 | /* |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1061 | * Fixup the pi_state owner with the new owner. |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1062 | * |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1063 | * Must be called with hash bucket lock held and mm->sem held for non |
| 1064 | * private futexes. |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1065 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1066 | 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] | 1067 | struct task_struct *newowner, int fshared) |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1068 | { |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1069 | u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1070 | struct futex_pi_state *pi_state = q->pi_state; |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1071 | struct task_struct *oldowner = pi_state->owner; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1072 | u32 uval, curval, newval; |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1073 | int ret, attempt = 0; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1074 | |
| 1075 | /* Owner died? */ |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1076 | if (!pi_state->owner) |
| 1077 | newtid |= FUTEX_OWNER_DIED; |
| 1078 | |
| 1079 | /* |
| 1080 | * We are here either because we stole the rtmutex from the |
| 1081 | * pending owner or we are the pending owner which failed to |
| 1082 | * get the rtmutex. We have to replace the pending owner TID |
| 1083 | * in the user space variable. This must be atomic as we have |
| 1084 | * to preserve the owner died bit here. |
| 1085 | * |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 1086 | * Note: We write the user space value _before_ changing the pi_state |
| 1087 | * because we can fault here. Imagine swapped out pages or a fork |
| 1088 | * that marked all the anonymous memory readonly for cow. |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1089 | * |
| 1090 | * Modifying pi_state _before_ the user space value would |
| 1091 | * leave the pi_state in an inconsistent state when we fault |
| 1092 | * here, because we need to drop the hash bucket lock to |
| 1093 | * handle the fault. This might be observed in the PID check |
| 1094 | * in lookup_pi_state. |
| 1095 | */ |
| 1096 | retry: |
| 1097 | if (get_futex_value_locked(&uval, uaddr)) |
| 1098 | goto handle_fault; |
| 1099 | |
| 1100 | while (1) { |
| 1101 | newval = (uval & FUTEX_OWNER_DIED) | newtid; |
| 1102 | |
| 1103 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
| 1104 | |
| 1105 | if (curval == -EFAULT) |
| 1106 | goto handle_fault; |
| 1107 | if (curval == uval) |
| 1108 | break; |
| 1109 | uval = curval; |
| 1110 | } |
| 1111 | |
| 1112 | /* |
| 1113 | * We fixed up user space. Now we need to fix the pi_state |
| 1114 | * itself. |
| 1115 | */ |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1116 | if (pi_state->owner != NULL) { |
| 1117 | spin_lock_irq(&pi_state->owner->pi_lock); |
| 1118 | WARN_ON(list_empty(&pi_state->list)); |
| 1119 | list_del_init(&pi_state->list); |
| 1120 | spin_unlock_irq(&pi_state->owner->pi_lock); |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1121 | } |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1122 | |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1123 | pi_state->owner = newowner; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1124 | |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1125 | spin_lock_irq(&newowner->pi_lock); |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1126 | WARN_ON(!list_empty(&pi_state->list)); |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1127 | list_add(&pi_state->list, &newowner->pi_state_list); |
| 1128 | spin_unlock_irq(&newowner->pi_lock); |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1129 | return 0; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1130 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1131 | /* |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1132 | * To handle the page fault we need to drop the hash bucket |
| 1133 | * lock here. That gives the other task (either the pending |
| 1134 | * owner itself or the task which stole the rtmutex) the |
| 1135 | * chance to try the fixup of the pi_state. So once we are |
| 1136 | * back from handling the fault we need to check the pi_state |
| 1137 | * after reacquiring the hash bucket lock and before trying to |
| 1138 | * do another fixup. When the fixup has been done already we |
| 1139 | * simply return. |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1140 | */ |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1141 | handle_fault: |
| 1142 | spin_unlock(q->lock_ptr); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1143 | |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1144 | ret = futex_handle_fault((unsigned long)uaddr, attempt++); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1145 | |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1146 | spin_lock(q->lock_ptr); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1147 | |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1148 | /* |
| 1149 | * Check if someone else fixed it for us: |
| 1150 | */ |
| 1151 | if (pi_state->owner != oldowner) |
| 1152 | return 0; |
| 1153 | |
| 1154 | if (ret) |
| 1155 | return ret; |
| 1156 | |
| 1157 | goto retry; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1158 | } |
| 1159 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1160 | /* |
| 1161 | * In case we must use restart_block to restart a futex_wait, |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1162 | * we encode in the 'flags' shared capability |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1163 | */ |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1164 | #define FLAGS_SHARED 0x01 |
| 1165 | #define FLAGS_CLOCKRT 0x02 |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1166 | |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1167 | static long futex_wait_restart(struct restart_block *restart); |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1168 | |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1169 | static int futex_wait(u32 __user *uaddr, int fshared, |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1170 | u32 val, ktime_t *abs_time, u32 bitset, int clockrt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1171 | { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1172 | struct task_struct *curr = current; |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1173 | struct restart_block *restart; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1174 | DECLARE_WAITQUEUE(wait, curr); |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1175 | struct futex_hash_bucket *hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1176 | struct futex_q q; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1177 | u32 uval; |
| 1178 | int ret; |
Thomas Gleixner | bd19723 | 2007-06-17 21:11:10 +0200 | [diff] [blame] | 1179 | struct hrtimer_sleeper t; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1180 | int rem = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1181 | |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1182 | if (!bitset) |
| 1183 | return -EINVAL; |
| 1184 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1185 | q.pi_state = NULL; |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1186 | q.bitset = bitset; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1187 | retry: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1188 | q.key = FUTEX_KEY_INIT; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1189 | ret = get_futex_key(uaddr, fshared, &q.key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1190 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1191 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1192 | |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1193 | hb = queue_lock(&q); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1194 | |
| 1195 | /* |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 1196 | * Access the page AFTER the hash-bucket is locked. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1197 | * Order is important: |
| 1198 | * |
| 1199 | * Userspace waiter: val = var; if (cond(val)) futex_wait(&var, val); |
| 1200 | * Userspace waker: if (cond(var)) { var = new; futex_wake(&var); } |
| 1201 | * |
| 1202 | * The basic logical guarantee of a futex is that it blocks ONLY |
| 1203 | * if cond(var) is known to be true at the time of blocking, for |
| 1204 | * any cond. If we queued after testing *uaddr, that would open |
| 1205 | * a race condition where we could block indefinitely with |
| 1206 | * cond(var) false, which would violate the guarantee. |
| 1207 | * |
| 1208 | * A consequence is that futex_wait() can return zero and absorb |
| 1209 | * a wakeup when *uaddr != val on entry to the syscall. This is |
| 1210 | * rare, but normal. |
| 1211 | * |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 1212 | * For shared futexes, we hold the mmap semaphore, so the mapping |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1213 | * cannot have changed since we looked it up in get_futex_key. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1214 | */ |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1215 | ret = get_futex_value_locked(&uval, uaddr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1216 | |
| 1217 | if (unlikely(ret)) { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1218 | queue_unlock(&q, hb); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1219 | put_futex_key(fshared, &q.key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1220 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1221 | ret = get_user(uval, uaddr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1222 | |
| 1223 | if (!ret) |
| 1224 | goto retry; |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1225 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1226 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1227 | ret = -EWOULDBLOCK; |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1228 | if (unlikely(uval != val)) { |
| 1229 | queue_unlock(&q, hb); |
| 1230 | goto out_put_key; |
| 1231 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1232 | |
| 1233 | /* Only actually queue if *uaddr contained val. */ |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1234 | queue_me(&q, hb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1235 | |
| 1236 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1237 | * There might have been scheduling since the queue_me(), as we |
| 1238 | * cannot hold a spinlock across the get_user() in case it |
| 1239 | * faults, and we cannot just set TASK_INTERRUPTIBLE state when |
| 1240 | * queueing ourselves into the futex hash. This code thus has to |
| 1241 | * rely on the futex_wake() code removing us from hash when it |
| 1242 | * wakes us up. |
| 1243 | */ |
| 1244 | |
| 1245 | /* add_wait_queue is the barrier after __set_current_state. */ |
| 1246 | __set_current_state(TASK_INTERRUPTIBLE); |
Darren Hart | 73500ac | 2008-12-17 17:29:56 -0800 | [diff] [blame] | 1247 | add_wait_queue(&q.waiter, &wait); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1248 | /* |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1249 | * !plist_node_empty() is safe here without any lock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1250 | * q.lock_ptr != 0 is not safe, because of ordering against wakeup. |
| 1251 | */ |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1252 | if (likely(!plist_node_empty(&q.list))) { |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1253 | if (!abs_time) |
| 1254 | schedule(); |
| 1255 | else { |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1256 | hrtimer_init_on_stack(&t.timer, |
| 1257 | clockrt ? CLOCK_REALTIME : |
| 1258 | CLOCK_MONOTONIC, |
| 1259 | HRTIMER_MODE_ABS); |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1260 | hrtimer_init_sleeper(&t, current); |
Darren Hart | 16f4993 | 2009-03-12 00:55:59 -0700 | [diff] [blame] | 1261 | hrtimer_set_expires_range_ns(&t.timer, *abs_time, |
| 1262 | current->timer_slack_ns); |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1263 | |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 1264 | hrtimer_start_expires(&t.timer, HRTIMER_MODE_ABS); |
Peter Zijlstra | 3588a08 | 2008-02-01 17:45:13 +0100 | [diff] [blame] | 1265 | if (!hrtimer_active(&t.timer)) |
| 1266 | t.task = NULL; |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1267 | |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1268 | /* |
| 1269 | * the timer could have already expired, in which |
| 1270 | * case current would be flagged for rescheduling. |
| 1271 | * Don't bother calling schedule. |
| 1272 | */ |
| 1273 | if (likely(t.task)) |
| 1274 | schedule(); |
| 1275 | |
| 1276 | hrtimer_cancel(&t.timer); |
| 1277 | |
| 1278 | /* Flag if a timeout occured */ |
| 1279 | rem = (t.task == NULL); |
Thomas Gleixner | 237fc6e | 2008-04-30 00:55:04 -0700 | [diff] [blame] | 1280 | |
| 1281 | destroy_hrtimer_on_stack(&t.timer); |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1282 | } |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1283 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1284 | __set_current_state(TASK_RUNNING); |
| 1285 | |
| 1286 | /* |
| 1287 | * NOTE: we don't remove ourselves from the waitqueue because |
| 1288 | * we are the only user of it. |
| 1289 | */ |
| 1290 | |
| 1291 | /* If we were woken (and unqueued), we succeeded, whatever. */ |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1292 | ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1293 | if (!unqueue_me(&q)) |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1294 | goto out_put_key; |
| 1295 | ret = -ETIMEDOUT; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1296 | if (rem) |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1297 | goto out_put_key; |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1298 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1299 | /* |
| 1300 | * We expect signal_pending(current), but another thread may |
| 1301 | * have handled it for us already. |
| 1302 | */ |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1303 | ret = -ERESTARTSYS; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1304 | if (!abs_time) |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1305 | goto out_put_key; |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1306 | |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1307 | restart = ¤t_thread_info()->restart_block; |
| 1308 | restart->fn = futex_wait_restart; |
| 1309 | restart->futex.uaddr = (u32 *)uaddr; |
| 1310 | restart->futex.val = val; |
| 1311 | restart->futex.time = abs_time->tv64; |
| 1312 | restart->futex.bitset = bitset; |
| 1313 | restart->futex.flags = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1314 | |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1315 | if (fshared) |
| 1316 | restart->futex.flags |= FLAGS_SHARED; |
| 1317 | if (clockrt) |
| 1318 | restart->futex.flags |= FLAGS_CLOCKRT; |
| 1319 | |
| 1320 | ret = -ERESTART_RESTARTBLOCK; |
| 1321 | |
| 1322 | out_put_key: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1323 | put_futex_key(fshared, &q.key); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1324 | out: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1325 | return ret; |
| 1326 | } |
| 1327 | |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1328 | |
| 1329 | static long futex_wait_restart(struct restart_block *restart) |
| 1330 | { |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1331 | u32 __user *uaddr = (u32 __user *)restart->futex.uaddr; |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1332 | int fshared = 0; |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1333 | ktime_t t; |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1334 | |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1335 | t.tv64 = restart->futex.time; |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1336 | restart->fn = do_no_restart_syscall; |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1337 | if (restart->futex.flags & FLAGS_SHARED) |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1338 | fshared = 1; |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1339 | return (long)futex_wait(uaddr, fshared, restart->futex.val, &t, |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1340 | restart->futex.bitset, |
| 1341 | restart->futex.flags & FLAGS_CLOCKRT); |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1342 | } |
| 1343 | |
| 1344 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1345 | /* |
| 1346 | * Userspace tried a 0 -> TID atomic transition of the futex value |
| 1347 | * and failed. The kernel side here does the whole locking operation: |
| 1348 | * if there are waiters then it will block, it does PI, etc. (Due to |
| 1349 | * races the kernel might see a 0 value of the futex too.) |
| 1350 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1351 | static int futex_lock_pi(u32 __user *uaddr, int fshared, |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1352 | int detect, ktime_t *time, int trylock) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1353 | { |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1354 | struct hrtimer_sleeper timeout, *to = NULL; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1355 | struct task_struct *curr = current; |
| 1356 | struct futex_hash_bucket *hb; |
| 1357 | u32 uval, newval, curval; |
| 1358 | struct futex_q q; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1359 | int ret, lock_taken, ownerdied = 0, attempt = 0; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1360 | |
| 1361 | if (refill_pi_state_cache()) |
| 1362 | return -ENOMEM; |
| 1363 | |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1364 | if (time) { |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1365 | to = &timeout; |
Thomas Gleixner | 237fc6e | 2008-04-30 00:55:04 -0700 | [diff] [blame] | 1366 | hrtimer_init_on_stack(&to->timer, CLOCK_REALTIME, |
| 1367 | HRTIMER_MODE_ABS); |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1368 | hrtimer_init_sleeper(to, current); |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 1369 | hrtimer_set_expires(&to->timer, *time); |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1370 | } |
| 1371 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1372 | q.pi_state = NULL; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1373 | retry: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1374 | q.key = FUTEX_KEY_INIT; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1375 | ret = get_futex_key(uaddr, fshared, &q.key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1376 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1377 | goto out; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1378 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1379 | retry_unlocked: |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1380 | hb = queue_lock(&q); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1381 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1382 | retry_locked: |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1383 | ret = lock_taken = 0; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1384 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1385 | /* |
| 1386 | * To avoid races, we attempt to take the lock here again |
| 1387 | * (by doing a 0 -> TID atomic cmpxchg), while holding all |
| 1388 | * the locks. It will most likely not succeed. |
| 1389 | */ |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1390 | newval = task_pid_vnr(current); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1391 | |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1392 | curval = cmpxchg_futex_value_locked(uaddr, 0, newval); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1393 | |
| 1394 | if (unlikely(curval == -EFAULT)) |
| 1395 | goto uaddr_faulted; |
| 1396 | |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1397 | /* |
| 1398 | * Detect deadlocks. In case of REQUEUE_PI this is a valid |
| 1399 | * situation and we return success to user space. |
| 1400 | */ |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1401 | if (unlikely((curval & FUTEX_TID_MASK) == task_pid_vnr(current))) { |
Thomas Gleixner | bd19723 | 2007-06-17 21:11:10 +0200 | [diff] [blame] | 1402 | ret = -EDEADLK; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1403 | goto out_unlock_put_key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1404 | } |
| 1405 | |
| 1406 | /* |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1407 | * Surprise - we got the lock. Just return to userspace: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1408 | */ |
| 1409 | if (unlikely(!curval)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1410 | goto out_unlock_put_key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1411 | |
| 1412 | uval = curval; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1413 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1414 | /* |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1415 | * Set the WAITERS flag, so the owner will know it has someone |
| 1416 | * to wake at next unlock |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1417 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1418 | newval = curval | FUTEX_WAITERS; |
| 1419 | |
| 1420 | /* |
| 1421 | * There are two cases, where a futex might have no owner (the |
Thomas Gleixner | bd19723 | 2007-06-17 21:11:10 +0200 | [diff] [blame] | 1422 | * owner TID is 0): OWNER_DIED. We take over the futex in this |
| 1423 | * case. We also do an unconditional take over, when the owner |
| 1424 | * of the futex died. |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1425 | * |
| 1426 | * This is safe as we are protected by the hash bucket lock ! |
| 1427 | */ |
| 1428 | if (unlikely(ownerdied || !(curval & FUTEX_TID_MASK))) { |
Thomas Gleixner | bd19723 | 2007-06-17 21:11:10 +0200 | [diff] [blame] | 1429 | /* Keep the OWNER_DIED bit */ |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1430 | newval = (curval & ~FUTEX_TID_MASK) | task_pid_vnr(current); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1431 | ownerdied = 0; |
| 1432 | lock_taken = 1; |
| 1433 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1434 | |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1435 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1436 | |
| 1437 | if (unlikely(curval == -EFAULT)) |
| 1438 | goto uaddr_faulted; |
| 1439 | if (unlikely(curval != uval)) |
| 1440 | goto retry_locked; |
| 1441 | |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1442 | /* |
Thomas Gleixner | bd19723 | 2007-06-17 21:11:10 +0200 | [diff] [blame] | 1443 | * We took the lock due to owner died take over. |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1444 | */ |
Thomas Gleixner | bd19723 | 2007-06-17 21:11:10 +0200 | [diff] [blame] | 1445 | if (unlikely(lock_taken)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1446 | goto out_unlock_put_key; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1447 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1448 | /* |
| 1449 | * We dont have the lock. Look up the PI state (or create it if |
| 1450 | * we are the first waiter): |
| 1451 | */ |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1452 | ret = lookup_pi_state(uval, hb, &q.key, &q.pi_state); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1453 | |
| 1454 | if (unlikely(ret)) { |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1455 | switch (ret) { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1456 | |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1457 | case -EAGAIN: |
| 1458 | /* |
| 1459 | * Task is exiting and we just wait for the |
| 1460 | * exit to complete. |
| 1461 | */ |
| 1462 | queue_unlock(&q, hb); |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 1463 | put_futex_key(fshared, &q.key); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1464 | cond_resched(); |
| 1465 | goto retry; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1466 | |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1467 | case -ESRCH: |
| 1468 | /* |
| 1469 | * No owner found for this futex. Check if the |
| 1470 | * OWNER_DIED bit is set to figure out whether |
| 1471 | * this is a robust futex or not. |
| 1472 | */ |
| 1473 | if (get_futex_value_locked(&curval, uaddr)) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1474 | goto uaddr_faulted; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1475 | |
| 1476 | /* |
| 1477 | * We simply start over in case of a robust |
| 1478 | * futex. The code above will take the futex |
| 1479 | * and return happy. |
| 1480 | */ |
| 1481 | if (curval & FUTEX_OWNER_DIED) { |
| 1482 | ownerdied = 1; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1483 | goto retry_locked; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1484 | } |
| 1485 | default: |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1486 | goto out_unlock_put_key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1487 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1488 | } |
| 1489 | |
| 1490 | /* |
| 1491 | * Only actually queue now that the atomic ops are done: |
| 1492 | */ |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1493 | queue_me(&q, hb); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1494 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1495 | WARN_ON(!q.pi_state); |
| 1496 | /* |
| 1497 | * Block on the PI mutex: |
| 1498 | */ |
| 1499 | if (!trylock) |
| 1500 | ret = rt_mutex_timed_lock(&q.pi_state->pi_mutex, to, 1); |
| 1501 | else { |
| 1502 | ret = rt_mutex_trylock(&q.pi_state->pi_mutex); |
| 1503 | /* Fixup the trylock return value: */ |
| 1504 | ret = ret ? 0 : -EWOULDBLOCK; |
| 1505 | } |
| 1506 | |
Vernon Mauery | a99e4e4 | 2006-07-01 04:35:42 -0700 | [diff] [blame] | 1507 | spin_lock(q.lock_ptr); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1508 | |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1509 | if (!ret) { |
| 1510 | /* |
| 1511 | * Got the lock. We might not be the anticipated owner |
| 1512 | * if we did a lock-steal - fix up the PI-state in |
| 1513 | * that case: |
| 1514 | */ |
| 1515 | if (q.pi_state->owner != curr) |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1516 | ret = fixup_pi_state_owner(uaddr, &q, curr, fshared); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1517 | } else { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1518 | /* |
| 1519 | * Catch the rare case, where the lock was released |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1520 | * when we were on the way back before we locked the |
| 1521 | * hash bucket. |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1522 | */ |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1523 | if (q.pi_state->owner == curr) { |
| 1524 | /* |
| 1525 | * Try to get the rt_mutex now. This might |
| 1526 | * fail as some other task acquired the |
| 1527 | * rt_mutex after we removed ourself from the |
| 1528 | * rt_mutex waiters list. |
| 1529 | */ |
| 1530 | if (rt_mutex_trylock(&q.pi_state->pi_mutex)) |
| 1531 | ret = 0; |
| 1532 | else { |
| 1533 | /* |
| 1534 | * pi_state is incorrect, some other |
| 1535 | * task did a lock steal and we |
| 1536 | * returned due to timeout or signal |
| 1537 | * without taking the rt_mutex. Too |
| 1538 | * late. We can access the |
| 1539 | * rt_mutex_owner without locking, as |
| 1540 | * the other task is now blocked on |
| 1541 | * the hash bucket lock. Fix the state |
| 1542 | * up. |
| 1543 | */ |
| 1544 | struct task_struct *owner; |
| 1545 | int res; |
| 1546 | |
| 1547 | owner = rt_mutex_owner(&q.pi_state->pi_mutex); |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1548 | res = fixup_pi_state_owner(uaddr, &q, owner, |
| 1549 | fshared); |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1550 | |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1551 | /* propagate -EFAULT, if the fixup failed */ |
| 1552 | if (res) |
| 1553 | ret = res; |
| 1554 | } |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1555 | } else { |
| 1556 | /* |
| 1557 | * Paranoia check. If we did not take the lock |
| 1558 | * in the trylock above, then we should not be |
| 1559 | * the owner of the rtmutex, neither the real |
| 1560 | * nor the pending one: |
| 1561 | */ |
| 1562 | if (rt_mutex_owner(&q.pi_state->pi_mutex) == curr) |
| 1563 | printk(KERN_ERR "futex_lock_pi: ret = %d " |
| 1564 | "pi-mutex: %p pi-state %p\n", ret, |
| 1565 | q.pi_state->pi_mutex.owner, |
| 1566 | q.pi_state->owner); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1567 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1568 | } |
| 1569 | |
Darren Hart | e8f6386 | 2009-03-12 00:56:06 -0700 | [diff] [blame^] | 1570 | /* |
| 1571 | * If fixup_pi_state_owner() faulted and was unable to handle the |
| 1572 | * fault, unlock it and return the fault to userspace. |
| 1573 | */ |
| 1574 | if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current)) |
| 1575 | rt_mutex_unlock(&q.pi_state->pi_mutex); |
| 1576 | |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1577 | /* Unqueue and drop the lock */ |
| 1578 | unqueue_me_pi(&q); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1579 | |
Thomas Gleixner | 237fc6e | 2008-04-30 00:55:04 -0700 | [diff] [blame] | 1580 | if (to) |
| 1581 | destroy_hrtimer_on_stack(&to->timer); |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1582 | return ret != -EINTR ? ret : -ERESTARTNOINTR; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1583 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1584 | out_unlock_put_key: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1585 | queue_unlock(&q, hb); |
| 1586 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1587 | out_put_key: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1588 | put_futex_key(fshared, &q.key); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1589 | out: |
Thomas Gleixner | 237fc6e | 2008-04-30 00:55:04 -0700 | [diff] [blame] | 1590 | if (to) |
| 1591 | destroy_hrtimer_on_stack(&to->timer); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1592 | return ret; |
| 1593 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1594 | uaddr_faulted: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1595 | /* |
Darren Hart | b568636 | 2008-12-18 15:06:34 -0800 | [diff] [blame] | 1596 | * We have to r/w *(int __user *)uaddr, and we have to modify it |
| 1597 | * atomically. Therefore, if we continue to fault after get_user() |
| 1598 | * below, we need to handle the fault ourselves, while still holding |
| 1599 | * the mmap_sem. This can occur if the uaddr is under contention as |
| 1600 | * we have to drop the mmap_sem in order to call get_user(). |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1601 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1602 | queue_unlock(&q, hb); |
| 1603 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1604 | if (attempt++) { |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1605 | ret = futex_handle_fault((unsigned long)uaddr, attempt); |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1606 | if (ret) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1607 | goto out_put_key; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1608 | goto retry_unlocked; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1609 | } |
| 1610 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1611 | ret = get_user(uval, uaddr); |
Darren Hart | b568636 | 2008-12-18 15:06:34 -0800 | [diff] [blame] | 1612 | if (!ret) |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 1613 | goto retry_unlocked; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1614 | |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 1615 | goto out_put_key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1616 | } |
| 1617 | |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 1618 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1619 | /* |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1620 | * Userspace attempted a TID -> 0 atomic transition, and failed. |
| 1621 | * This is the in-kernel slowpath: we look up the PI state (if any), |
| 1622 | * and do the rt-mutex unlock. |
| 1623 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1624 | static int futex_unlock_pi(u32 __user *uaddr, int fshared) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1625 | { |
| 1626 | struct futex_hash_bucket *hb; |
| 1627 | struct futex_q *this, *next; |
| 1628 | u32 uval; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1629 | struct plist_head *head; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1630 | union futex_key key = FUTEX_KEY_INIT; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1631 | int ret, attempt = 0; |
| 1632 | |
| 1633 | retry: |
| 1634 | if (get_user(uval, uaddr)) |
| 1635 | return -EFAULT; |
| 1636 | /* |
| 1637 | * We release only a lock we actually own: |
| 1638 | */ |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1639 | if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current)) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1640 | return -EPERM; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1641 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1642 | ret = get_futex_key(uaddr, fshared, &key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1643 | if (unlikely(ret != 0)) |
| 1644 | goto out; |
| 1645 | |
| 1646 | hb = hash_futex(&key); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1647 | retry_unlocked: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1648 | spin_lock(&hb->lock); |
| 1649 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1650 | /* |
| 1651 | * To avoid races, try to do the TID -> 0 atomic transition |
| 1652 | * again. If it succeeds then we can return without waking |
| 1653 | * anyone else up: |
| 1654 | */ |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1655 | if (!(uval & FUTEX_OWNER_DIED)) |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1656 | uval = cmpxchg_futex_value_locked(uaddr, task_pid_vnr(current), 0); |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1657 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1658 | |
| 1659 | if (unlikely(uval == -EFAULT)) |
| 1660 | goto pi_faulted; |
| 1661 | /* |
| 1662 | * Rare case: we managed to release the lock atomically, |
| 1663 | * no need to wake anyone else up: |
| 1664 | */ |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1665 | if (unlikely(uval == task_pid_vnr(current))) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1666 | goto out_unlock; |
| 1667 | |
| 1668 | /* |
| 1669 | * Ok, other tasks may need to be woken up - check waiters |
| 1670 | * and do the wakeup if necessary: |
| 1671 | */ |
| 1672 | head = &hb->chain; |
| 1673 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1674 | plist_for_each_entry_safe(this, next, head, list) { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1675 | if (!match_futex (&this->key, &key)) |
| 1676 | continue; |
| 1677 | ret = wake_futex_pi(uaddr, uval, this); |
| 1678 | /* |
| 1679 | * The atomic access to the futex value |
| 1680 | * generated a pagefault, so retry the |
| 1681 | * user-access and the wakeup: |
| 1682 | */ |
| 1683 | if (ret == -EFAULT) |
| 1684 | goto pi_faulted; |
| 1685 | goto out_unlock; |
| 1686 | } |
| 1687 | /* |
| 1688 | * No waiters - kernel unlocks the futex: |
| 1689 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1690 | if (!(uval & FUTEX_OWNER_DIED)) { |
| 1691 | ret = unlock_futex_pi(uaddr, uval); |
| 1692 | if (ret == -EFAULT) |
| 1693 | goto pi_faulted; |
| 1694 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1695 | |
| 1696 | out_unlock: |
| 1697 | spin_unlock(&hb->lock); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1698 | put_futex_key(fshared, &key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1699 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1700 | out: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1701 | return ret; |
| 1702 | |
| 1703 | pi_faulted: |
| 1704 | /* |
Darren Hart | b568636 | 2008-12-18 15:06:34 -0800 | [diff] [blame] | 1705 | * We have to r/w *(int __user *)uaddr, and we have to modify it |
| 1706 | * atomically. Therefore, if we continue to fault after get_user() |
| 1707 | * below, we need to handle the fault ourselves, while still holding |
| 1708 | * the mmap_sem. This can occur if the uaddr is under contention as |
| 1709 | * we have to drop the mmap_sem in order to call get_user(). |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1710 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1711 | spin_unlock(&hb->lock); |
| 1712 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1713 | if (attempt++) { |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1714 | ret = futex_handle_fault((unsigned long)uaddr, attempt); |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1715 | if (ret) |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1716 | goto out; |
john stultz | 187226f | 2007-08-22 14:01:10 -0700 | [diff] [blame] | 1717 | uval = 0; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1718 | goto retry_unlocked; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1719 | } |
| 1720 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1721 | ret = get_user(uval, uaddr); |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 1722 | put_futex_key(fshared, &key); |
Darren Hart | b568636 | 2008-12-18 15:06:34 -0800 | [diff] [blame] | 1723 | if (!ret) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1724 | goto retry; |
| 1725 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1726 | return ret; |
| 1727 | } |
| 1728 | |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1729 | /* |
| 1730 | * Support for robust futexes: the kernel cleans up held futexes at |
| 1731 | * thread exit time. |
| 1732 | * |
| 1733 | * Implementation: user-space maintains a per-thread list of locks it |
| 1734 | * is holding. Upon do_exit(), the kernel carefully walks this list, |
| 1735 | * and marks all locks that are owned by this thread with the |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1736 | * 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] | 1737 | * always manipulated with the lock held, so the list is private and |
| 1738 | * per-thread. Userspace also maintains a per-thread 'list_op_pending' |
| 1739 | * field, to allow the kernel to clean up if the thread dies after |
| 1740 | * acquiring the lock, but just before it could have added itself to |
| 1741 | * the list. There can only be one such pending lock. |
| 1742 | */ |
| 1743 | |
| 1744 | /** |
| 1745 | * sys_set_robust_list - set the robust-futex list head of a task |
| 1746 | * @head: pointer to the list-head |
| 1747 | * @len: length of the list-head, as userspace expects |
| 1748 | */ |
Heiko Carstens | 836f92a | 2009-01-14 14:14:33 +0100 | [diff] [blame] | 1749 | SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head, |
| 1750 | size_t, len) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1751 | { |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 1752 | if (!futex_cmpxchg_enabled) |
| 1753 | return -ENOSYS; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1754 | /* |
| 1755 | * The kernel knows only one size for now: |
| 1756 | */ |
| 1757 | if (unlikely(len != sizeof(*head))) |
| 1758 | return -EINVAL; |
| 1759 | |
| 1760 | current->robust_list = head; |
| 1761 | |
| 1762 | return 0; |
| 1763 | } |
| 1764 | |
| 1765 | /** |
| 1766 | * sys_get_robust_list - get the robust-futex list head of a task |
| 1767 | * @pid: pid of the process [zero for current task] |
| 1768 | * @head_ptr: pointer to a list-head pointer, the kernel fills it in |
| 1769 | * @len_ptr: pointer to a length field, the kernel fills in the header size |
| 1770 | */ |
Heiko Carstens | 836f92a | 2009-01-14 14:14:33 +0100 | [diff] [blame] | 1771 | SYSCALL_DEFINE3(get_robust_list, int, pid, |
| 1772 | struct robust_list_head __user * __user *, head_ptr, |
| 1773 | size_t __user *, len_ptr) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1774 | { |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 1775 | struct robust_list_head __user *head; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1776 | unsigned long ret; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 1777 | const struct cred *cred = current_cred(), *pcred; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1778 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 1779 | if (!futex_cmpxchg_enabled) |
| 1780 | return -ENOSYS; |
| 1781 | |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1782 | if (!pid) |
| 1783 | head = current->robust_list; |
| 1784 | else { |
| 1785 | struct task_struct *p; |
| 1786 | |
| 1787 | ret = -ESRCH; |
Oleg Nesterov | aaa2a97 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 1788 | rcu_read_lock(); |
Pavel Emelyanov | 228ebcb | 2007-10-18 23:40:16 -0700 | [diff] [blame] | 1789 | p = find_task_by_vpid(pid); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1790 | if (!p) |
| 1791 | goto err_unlock; |
| 1792 | ret = -EPERM; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 1793 | pcred = __task_cred(p); |
| 1794 | if (cred->euid != pcred->euid && |
| 1795 | cred->euid != pcred->uid && |
David Howells | 76aac0e | 2008-11-14 10:39:12 +1100 | [diff] [blame] | 1796 | !capable(CAP_SYS_PTRACE)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1797 | goto err_unlock; |
| 1798 | head = p->robust_list; |
Oleg Nesterov | aaa2a97 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 1799 | rcu_read_unlock(); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1800 | } |
| 1801 | |
| 1802 | if (put_user(sizeof(*head), len_ptr)) |
| 1803 | return -EFAULT; |
| 1804 | return put_user(head, head_ptr); |
| 1805 | |
| 1806 | err_unlock: |
Oleg Nesterov | aaa2a97 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 1807 | rcu_read_unlock(); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1808 | |
| 1809 | return ret; |
| 1810 | } |
| 1811 | |
| 1812 | /* |
| 1813 | * Process a futex-list entry, check whether it's owned by the |
| 1814 | * dying task, and do notification if so: |
| 1815 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1816 | 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] | 1817 | { |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1818 | u32 uval, nval, mval; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1819 | |
Ingo Molnar | 8f17d3a | 2006-03-27 01:16:27 -0800 | [diff] [blame] | 1820 | retry: |
| 1821 | if (get_user(uval, uaddr)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1822 | return -1; |
| 1823 | |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1824 | if ((uval & FUTEX_TID_MASK) == task_pid_vnr(curr)) { |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1825 | /* |
| 1826 | * Ok, this dying thread is truly holding a futex |
| 1827 | * of interest. Set the OWNER_DIED bit atomically |
| 1828 | * via cmpxchg, and if the value had FUTEX_WAITERS |
| 1829 | * set, wake up a waiter (if any). (We have to do a |
| 1830 | * futex_wake() even if OWNER_DIED is already set - |
| 1831 | * to handle the rare but possible case of recursive |
| 1832 | * thread-death.) The rest of the cleanup is done in |
| 1833 | * userspace. |
| 1834 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1835 | mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; |
| 1836 | nval = futex_atomic_cmpxchg_inatomic(uaddr, uval, mval); |
| 1837 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1838 | if (nval == -EFAULT) |
| 1839 | return -1; |
| 1840 | |
| 1841 | if (nval != uval) |
Ingo Molnar | 8f17d3a | 2006-03-27 01:16:27 -0800 | [diff] [blame] | 1842 | goto retry; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1843 | |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1844 | /* |
| 1845 | * Wake robust non-PI futexes here. The wakeup of |
| 1846 | * PI futexes happens in exit_pi_state(): |
| 1847 | */ |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1848 | if (!pi && (uval & FUTEX_WAITERS)) |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1849 | futex_wake(uaddr, 1, 1, FUTEX_BITSET_MATCH_ANY); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1850 | } |
| 1851 | return 0; |
| 1852 | } |
| 1853 | |
| 1854 | /* |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1855 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: |
| 1856 | */ |
| 1857 | static inline int fetch_robust_entry(struct robust_list __user **entry, |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 1858 | struct robust_list __user * __user *head, |
| 1859 | int *pi) |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1860 | { |
| 1861 | unsigned long uentry; |
| 1862 | |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 1863 | if (get_user(uentry, (unsigned long __user *)head)) |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1864 | return -EFAULT; |
| 1865 | |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 1866 | *entry = (void __user *)(uentry & ~1UL); |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1867 | *pi = uentry & 1; |
| 1868 | |
| 1869 | return 0; |
| 1870 | } |
| 1871 | |
| 1872 | /* |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1873 | * Walk curr->robust_list (very carefully, it's a userspace list!) |
| 1874 | * and mark any locks found there dead, and notify any waiters. |
| 1875 | * |
| 1876 | * We silently return on any sign of list-walking problem. |
| 1877 | */ |
| 1878 | void exit_robust_list(struct task_struct *curr) |
| 1879 | { |
| 1880 | struct robust_list_head __user *head = curr->robust_list; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1881 | struct robust_list __user *entry, *next_entry, *pending; |
| 1882 | unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1883 | unsigned long futex_offset; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1884 | int rc; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1885 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 1886 | if (!futex_cmpxchg_enabled) |
| 1887 | return; |
| 1888 | |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1889 | /* |
| 1890 | * Fetch the list head (which was registered earlier, via |
| 1891 | * sys_set_robust_list()): |
| 1892 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1893 | if (fetch_robust_entry(&entry, &head->list.next, &pi)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1894 | return; |
| 1895 | /* |
| 1896 | * Fetch the relative futex offset: |
| 1897 | */ |
| 1898 | if (get_user(futex_offset, &head->futex_offset)) |
| 1899 | return; |
| 1900 | /* |
| 1901 | * Fetch any possibly pending lock-add first, and handle it |
| 1902 | * if it exists: |
| 1903 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1904 | if (fetch_robust_entry(&pending, &head->list_op_pending, &pip)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1905 | return; |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1906 | |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1907 | next_entry = NULL; /* avoid warning with gcc */ |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1908 | while (entry != &head->list) { |
| 1909 | /* |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1910 | * Fetch the next entry in the list before calling |
| 1911 | * handle_futex_death: |
| 1912 | */ |
| 1913 | rc = fetch_robust_entry(&next_entry, &entry->next, &next_pi); |
| 1914 | /* |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1915 | * A pending lock might already be on the list, so |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1916 | * don't process it twice: |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1917 | */ |
| 1918 | if (entry != pending) |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 1919 | if (handle_futex_death((void __user *)entry + futex_offset, |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1920 | curr, pi)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1921 | return; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1922 | if (rc) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1923 | return; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1924 | entry = next_entry; |
| 1925 | pi = next_pi; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1926 | /* |
| 1927 | * Avoid excessively long or circular lists: |
| 1928 | */ |
| 1929 | if (!--limit) |
| 1930 | break; |
| 1931 | |
| 1932 | cond_resched(); |
| 1933 | } |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1934 | |
| 1935 | if (pending) |
| 1936 | handle_futex_death((void __user *)pending + futex_offset, |
| 1937 | curr, pip); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1938 | } |
| 1939 | |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1940 | 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] | 1941 | u32 __user *uaddr2, u32 val2, u32 val3) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1942 | { |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1943 | int clockrt, ret = -ENOSYS; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1944 | int cmd = op & FUTEX_CMD_MASK; |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1945 | int fshared = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1946 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1947 | if (!(op & FUTEX_PRIVATE_FLAG)) |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1948 | fshared = 1; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1949 | |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1950 | clockrt = op & FUTEX_CLOCK_REALTIME; |
| 1951 | if (clockrt && cmd != FUTEX_WAIT_BITSET) |
| 1952 | return -ENOSYS; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1953 | |
| 1954 | switch (cmd) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1955 | case FUTEX_WAIT: |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1956 | val3 = FUTEX_BITSET_MATCH_ANY; |
| 1957 | case FUTEX_WAIT_BITSET: |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1958 | ret = futex_wait(uaddr, fshared, val, timeout, val3, clockrt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1959 | break; |
| 1960 | case FUTEX_WAKE: |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1961 | val3 = FUTEX_BITSET_MATCH_ANY; |
| 1962 | case FUTEX_WAKE_BITSET: |
| 1963 | ret = futex_wake(uaddr, fshared, val, val3); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1964 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1965 | case FUTEX_REQUEUE: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1966 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1967 | break; |
| 1968 | case FUTEX_CMP_REQUEUE: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1969 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1970 | break; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 1971 | case FUTEX_WAKE_OP: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1972 | ret = futex_wake_op(uaddr, fshared, uaddr2, val, val2, val3); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 1973 | break; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1974 | case FUTEX_LOCK_PI: |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 1975 | if (futex_cmpxchg_enabled) |
| 1976 | ret = futex_lock_pi(uaddr, fshared, val, timeout, 0); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1977 | break; |
| 1978 | case FUTEX_UNLOCK_PI: |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 1979 | if (futex_cmpxchg_enabled) |
| 1980 | ret = futex_unlock_pi(uaddr, fshared); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1981 | break; |
| 1982 | case FUTEX_TRYLOCK_PI: |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 1983 | if (futex_cmpxchg_enabled) |
| 1984 | ret = futex_lock_pi(uaddr, fshared, 0, timeout, 1); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1985 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1986 | default: |
| 1987 | ret = -ENOSYS; |
| 1988 | } |
| 1989 | return ret; |
| 1990 | } |
| 1991 | |
| 1992 | |
Heiko Carstens | 17da2bd | 2009-01-14 14:14:10 +0100 | [diff] [blame] | 1993 | SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, |
| 1994 | struct timespec __user *, utime, u32 __user *, uaddr2, |
| 1995 | u32, val3) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1996 | { |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1997 | struct timespec ts; |
| 1998 | ktime_t t, *tp = NULL; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1999 | u32 val2 = 0; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2000 | int cmd = op & FUTEX_CMD_MASK; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2001 | |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 2002 | if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
| 2003 | cmd == FUTEX_WAIT_BITSET)) { |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2004 | if (copy_from_user(&ts, utime, sizeof(ts)) != 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2005 | return -EFAULT; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2006 | if (!timespec_valid(&ts)) |
Thomas Gleixner | 9741ef96 | 2006-03-31 02:31:32 -0800 | [diff] [blame] | 2007 | return -EINVAL; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2008 | |
| 2009 | t = timespec_to_ktime(ts); |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2010 | if (cmd == FUTEX_WAIT) |
Thomas Gleixner | 5a7780e | 2008-02-13 09:20:43 +0100 | [diff] [blame] | 2011 | t = ktime_add_safe(ktime_get(), t); |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2012 | tp = &t; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2013 | } |
| 2014 | /* |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2015 | * requeue parameter in 'utime' if cmd == FUTEX_REQUEUE. |
Andreas Schwab | f54f098 | 2007-07-31 00:38:51 -0700 | [diff] [blame] | 2016 | * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2017 | */ |
Andreas Schwab | f54f098 | 2007-07-31 00:38:51 -0700 | [diff] [blame] | 2018 | if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
| 2019 | cmd == FUTEX_WAKE_OP) |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 2020 | val2 = (u32) (unsigned long) utime; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2021 | |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2022 | return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2023 | } |
| 2024 | |
Benjamin Herrenschmidt | f6d107f | 2008-03-27 14:52:15 +1100 | [diff] [blame] | 2025 | static int __init futex_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2026 | { |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2027 | u32 curval; |
Thomas Gleixner | 3e4ab74 | 2008-02-23 15:23:55 -0800 | [diff] [blame] | 2028 | int i; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2029 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2030 | /* |
| 2031 | * This will fail and we want it. Some arch implementations do |
| 2032 | * runtime detection of the futex_atomic_cmpxchg_inatomic() |
| 2033 | * functionality. We want to know that before we call in any |
| 2034 | * of the complex code paths. Also we want to prevent |
| 2035 | * registration of robust lists in that case. NULL is |
| 2036 | * guaranteed to fault and we get -EFAULT on functional |
| 2037 | * implementation, the non functional ones will return |
| 2038 | * -ENOSYS. |
| 2039 | */ |
| 2040 | curval = cmpxchg_futex_value_locked(NULL, 0, 0); |
| 2041 | if (curval == -EFAULT) |
| 2042 | futex_cmpxchg_enabled = 1; |
| 2043 | |
Thomas Gleixner | 3e4ab74 | 2008-02-23 15:23:55 -0800 | [diff] [blame] | 2044 | for (i = 0; i < ARRAY_SIZE(futex_queues); i++) { |
| 2045 | plist_head_init(&futex_queues[i].chain, &futex_queues[i].lock); |
| 2046 | spin_lock_init(&futex_queues[i].lock); |
| 2047 | } |
| 2048 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2049 | return 0; |
| 2050 | } |
Benjamin Herrenschmidt | f6d107f | 2008-03-27 14:52:15 +1100 | [diff] [blame] | 2051 | __initcall(futex_init); |