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 | |
Darren Hart | 4b1c486 | 2009-04-03 13:39:42 -0700 | [diff] [blame] | 279 | /** |
| 280 | * futex_top_waiter() - Return the highest priority waiter on a futex |
| 281 | * @hb: the hash bucket the futex_q's reside in |
| 282 | * @key: the futex key (to distinguish it from other futex futex_q's) |
| 283 | * |
| 284 | * Must be called with the hb lock held. |
| 285 | */ |
| 286 | static struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb, |
| 287 | union futex_key *key) |
| 288 | { |
| 289 | struct futex_q *this; |
| 290 | |
| 291 | plist_for_each_entry(this, &hb->chain, list) { |
| 292 | if (match_futex(&this->key, key)) |
| 293 | return this; |
| 294 | } |
| 295 | return NULL; |
| 296 | } |
| 297 | |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 298 | static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval) |
| 299 | { |
| 300 | u32 curval; |
| 301 | |
| 302 | pagefault_disable(); |
| 303 | curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval); |
| 304 | pagefault_enable(); |
| 305 | |
| 306 | return curval; |
| 307 | } |
| 308 | |
| 309 | static int get_futex_value_locked(u32 *dest, u32 __user *from) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 310 | { |
| 311 | int ret; |
| 312 | |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame] | 313 | pagefault_disable(); |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 314 | ret = __copy_from_user_inatomic(dest, from, sizeof(u32)); |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame] | 315 | pagefault_enable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 316 | |
| 317 | return ret ? -EFAULT : 0; |
| 318 | } |
| 319 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 320 | |
| 321 | /* |
| 322 | * PI code: |
| 323 | */ |
| 324 | static int refill_pi_state_cache(void) |
| 325 | { |
| 326 | struct futex_pi_state *pi_state; |
| 327 | |
| 328 | if (likely(current->pi_state_cache)) |
| 329 | return 0; |
| 330 | |
Burman Yan | 4668edc | 2006-12-06 20:38:51 -0800 | [diff] [blame] | 331 | pi_state = kzalloc(sizeof(*pi_state), GFP_KERNEL); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 332 | |
| 333 | if (!pi_state) |
| 334 | return -ENOMEM; |
| 335 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 336 | INIT_LIST_HEAD(&pi_state->list); |
| 337 | /* pi_mutex gets initialized later */ |
| 338 | pi_state->owner = NULL; |
| 339 | atomic_set(&pi_state->refcount, 1); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 340 | pi_state->key = FUTEX_KEY_INIT; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 341 | |
| 342 | current->pi_state_cache = pi_state; |
| 343 | |
| 344 | return 0; |
| 345 | } |
| 346 | |
| 347 | static struct futex_pi_state * alloc_pi_state(void) |
| 348 | { |
| 349 | struct futex_pi_state *pi_state = current->pi_state_cache; |
| 350 | |
| 351 | WARN_ON(!pi_state); |
| 352 | current->pi_state_cache = NULL; |
| 353 | |
| 354 | return pi_state; |
| 355 | } |
| 356 | |
| 357 | static void free_pi_state(struct futex_pi_state *pi_state) |
| 358 | { |
| 359 | if (!atomic_dec_and_test(&pi_state->refcount)) |
| 360 | return; |
| 361 | |
| 362 | /* |
| 363 | * If pi_state->owner is NULL, the owner is most probably dying |
| 364 | * and has cleaned up the pi_state already |
| 365 | */ |
| 366 | if (pi_state->owner) { |
| 367 | spin_lock_irq(&pi_state->owner->pi_lock); |
| 368 | list_del_init(&pi_state->list); |
| 369 | spin_unlock_irq(&pi_state->owner->pi_lock); |
| 370 | |
| 371 | rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner); |
| 372 | } |
| 373 | |
| 374 | if (current->pi_state_cache) |
| 375 | kfree(pi_state); |
| 376 | else { |
| 377 | /* |
| 378 | * pi_state->list is already empty. |
| 379 | * clear pi_state->owner. |
| 380 | * refcount is at 0 - put it back to 1. |
| 381 | */ |
| 382 | pi_state->owner = NULL; |
| 383 | atomic_set(&pi_state->refcount, 1); |
| 384 | current->pi_state_cache = pi_state; |
| 385 | } |
| 386 | } |
| 387 | |
| 388 | /* |
| 389 | * Look up the task based on what TID userspace gave us. |
| 390 | * We dont trust it. |
| 391 | */ |
| 392 | static struct task_struct * futex_find_get_task(pid_t pid) |
| 393 | { |
| 394 | struct task_struct *p; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 395 | const struct cred *cred = current_cred(), *pcred; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 396 | |
Oleg Nesterov | d359b54 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 397 | rcu_read_lock(); |
Pavel Emelyanov | 228ebcb | 2007-10-18 23:40:16 -0700 | [diff] [blame] | 398 | p = find_task_by_vpid(pid); |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 399 | if (!p) { |
Thomas Gleixner | a06381f | 2007-06-23 11:48:40 +0200 | [diff] [blame] | 400 | p = ERR_PTR(-ESRCH); |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 401 | } else { |
| 402 | pcred = __task_cred(p); |
| 403 | if (cred->euid != pcred->euid && |
| 404 | cred->euid != pcred->uid) |
| 405 | p = ERR_PTR(-ESRCH); |
| 406 | else |
| 407 | get_task_struct(p); |
| 408 | } |
Thomas Gleixner | a06381f | 2007-06-23 11:48:40 +0200 | [diff] [blame] | 409 | |
Oleg Nesterov | d359b54 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 410 | rcu_read_unlock(); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 411 | |
| 412 | return p; |
| 413 | } |
| 414 | |
| 415 | /* |
| 416 | * This task is holding PI mutexes at exit time => bad. |
| 417 | * Kernel cleans up PI-state, but userspace is likely hosed. |
| 418 | * (Robust-futex cleanup is separate and might save the day for userspace.) |
| 419 | */ |
| 420 | void exit_pi_state_list(struct task_struct *curr) |
| 421 | { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 422 | struct list_head *next, *head = &curr->pi_state_list; |
| 423 | struct futex_pi_state *pi_state; |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 424 | struct futex_hash_bucket *hb; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 425 | union futex_key key = FUTEX_KEY_INIT; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 426 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 427 | if (!futex_cmpxchg_enabled) |
| 428 | return; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 429 | /* |
| 430 | * We are a ZOMBIE and nobody can enqueue itself on |
| 431 | * pi_state_list anymore, but we have to be careful |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 432 | * versus waiters unqueueing themselves: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 433 | */ |
| 434 | spin_lock_irq(&curr->pi_lock); |
| 435 | while (!list_empty(head)) { |
| 436 | |
| 437 | next = head->next; |
| 438 | pi_state = list_entry(next, struct futex_pi_state, list); |
| 439 | key = pi_state->key; |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 440 | hb = hash_futex(&key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 441 | spin_unlock_irq(&curr->pi_lock); |
| 442 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 443 | spin_lock(&hb->lock); |
| 444 | |
| 445 | spin_lock_irq(&curr->pi_lock); |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 446 | /* |
| 447 | * We dropped the pi-lock, so re-check whether this |
| 448 | * task still owns the PI-state: |
| 449 | */ |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 450 | if (head->next != next) { |
| 451 | spin_unlock(&hb->lock); |
| 452 | continue; |
| 453 | } |
| 454 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 455 | WARN_ON(pi_state->owner != curr); |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 456 | WARN_ON(list_empty(&pi_state->list)); |
| 457 | list_del_init(&pi_state->list); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 458 | pi_state->owner = NULL; |
| 459 | spin_unlock_irq(&curr->pi_lock); |
| 460 | |
| 461 | rt_mutex_unlock(&pi_state->pi_mutex); |
| 462 | |
| 463 | spin_unlock(&hb->lock); |
| 464 | |
| 465 | spin_lock_irq(&curr->pi_lock); |
| 466 | } |
| 467 | spin_unlock_irq(&curr->pi_lock); |
| 468 | } |
| 469 | |
| 470 | static int |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 471 | lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, |
| 472 | union futex_key *key, struct futex_pi_state **ps) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 473 | { |
| 474 | struct futex_pi_state *pi_state = NULL; |
| 475 | struct futex_q *this, *next; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 476 | struct plist_head *head; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 477 | struct task_struct *p; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 478 | pid_t pid = uval & FUTEX_TID_MASK; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 479 | |
| 480 | head = &hb->chain; |
| 481 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 482 | plist_for_each_entry_safe(this, next, head, list) { |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 483 | if (match_futex(&this->key, key)) { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 484 | /* |
| 485 | * Another waiter already exists - bump up |
| 486 | * the refcount and return its pi_state: |
| 487 | */ |
| 488 | pi_state = this->pi_state; |
Thomas Gleixner | 06a9ec2 | 2006-07-10 04:44:30 -0700 | [diff] [blame] | 489 | /* |
| 490 | * Userspace might have messed up non PI and PI futexes |
| 491 | */ |
| 492 | if (unlikely(!pi_state)) |
| 493 | return -EINVAL; |
| 494 | |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 495 | WARN_ON(!atomic_read(&pi_state->refcount)); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 496 | WARN_ON(pid && pi_state->owner && |
| 497 | pi_state->owner->pid != pid); |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 498 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 499 | atomic_inc(&pi_state->refcount); |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 500 | *ps = pi_state; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 501 | |
| 502 | return 0; |
| 503 | } |
| 504 | } |
| 505 | |
| 506 | /* |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 507 | * 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] | 508 | * the new pi_state to it, but bail out when TID = 0 |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 509 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 510 | if (!pid) |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 511 | return -ESRCH; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 512 | p = futex_find_get_task(pid); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 513 | if (IS_ERR(p)) |
| 514 | return PTR_ERR(p); |
| 515 | |
| 516 | /* |
| 517 | * We need to look at the task state flags to figure out, |
| 518 | * whether the task is exiting. To protect against the do_exit |
| 519 | * change of the task flags, we do this protected by |
| 520 | * p->pi_lock: |
| 521 | */ |
| 522 | spin_lock_irq(&p->pi_lock); |
| 523 | if (unlikely(p->flags & PF_EXITING)) { |
| 524 | /* |
| 525 | * The task is on the way out. When PF_EXITPIDONE is |
| 526 | * set, we know that the task has finished the |
| 527 | * cleanup: |
| 528 | */ |
| 529 | int ret = (p->flags & PF_EXITPIDONE) ? -ESRCH : -EAGAIN; |
| 530 | |
| 531 | spin_unlock_irq(&p->pi_lock); |
| 532 | put_task_struct(p); |
| 533 | return ret; |
| 534 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 535 | |
| 536 | pi_state = alloc_pi_state(); |
| 537 | |
| 538 | /* |
| 539 | * Initialize the pi_mutex in locked state and make 'p' |
| 540 | * the owner of it: |
| 541 | */ |
| 542 | rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p); |
| 543 | |
| 544 | /* Store the key for possible exit cleanups: */ |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 545 | pi_state->key = *key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 546 | |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 547 | WARN_ON(!list_empty(&pi_state->list)); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 548 | list_add(&pi_state->list, &p->pi_state_list); |
| 549 | pi_state->owner = p; |
| 550 | spin_unlock_irq(&p->pi_lock); |
| 551 | |
| 552 | put_task_struct(p); |
| 553 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 554 | *ps = pi_state; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 555 | |
| 556 | return 0; |
| 557 | } |
| 558 | |
Darren Hart | 1a52084 | 2009-04-03 13:39:52 -0700 | [diff] [blame] | 559 | /** |
| 560 | * futex_lock_pi_atomic() - atomic work required to acquire a pi aware futex |
| 561 | * @uaddr: the pi futex user address |
| 562 | * @hb: the pi futex hash bucket |
| 563 | * @key: the futex key associated with uaddr and hb |
| 564 | * @ps: the pi_state pointer where we store the result of the lookup |
| 565 | * @task: the task to perform the atomic lock work for. This will be |
| 566 | * "current" except in the case of requeue pi. |
| 567 | * |
| 568 | * Returns: |
| 569 | * 0 - ready to wait |
| 570 | * 1 - acquired the lock |
| 571 | * <0 - error |
| 572 | * |
| 573 | * The hb->lock and futex_key refs shall be held by the caller. |
| 574 | */ |
| 575 | static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb, |
| 576 | union futex_key *key, |
| 577 | struct futex_pi_state **ps, |
| 578 | struct task_struct *task) |
| 579 | { |
| 580 | int lock_taken, ret, ownerdied = 0; |
| 581 | u32 uval, newval, curval; |
| 582 | |
| 583 | retry: |
| 584 | ret = lock_taken = 0; |
| 585 | |
| 586 | /* |
| 587 | * To avoid races, we attempt to take the lock here again |
| 588 | * (by doing a 0 -> TID atomic cmpxchg), while holding all |
| 589 | * the locks. It will most likely not succeed. |
| 590 | */ |
| 591 | newval = task_pid_vnr(task); |
| 592 | |
| 593 | curval = cmpxchg_futex_value_locked(uaddr, 0, newval); |
| 594 | |
| 595 | if (unlikely(curval == -EFAULT)) |
| 596 | return -EFAULT; |
| 597 | |
| 598 | /* |
| 599 | * Detect deadlocks. |
| 600 | */ |
| 601 | if ((unlikely((curval & FUTEX_TID_MASK) == task_pid_vnr(task)))) |
| 602 | return -EDEADLK; |
| 603 | |
| 604 | /* |
| 605 | * Surprise - we got the lock. Just return to userspace: |
| 606 | */ |
| 607 | if (unlikely(!curval)) |
| 608 | return 1; |
| 609 | |
| 610 | uval = curval; |
| 611 | |
| 612 | /* |
| 613 | * Set the FUTEX_WAITERS flag, so the owner will know it has someone |
| 614 | * to wake at the next unlock. |
| 615 | */ |
| 616 | newval = curval | FUTEX_WAITERS; |
| 617 | |
| 618 | /* |
| 619 | * There are two cases, where a futex might have no owner (the |
| 620 | * owner TID is 0): OWNER_DIED. We take over the futex in this |
| 621 | * case. We also do an unconditional take over, when the owner |
| 622 | * of the futex died. |
| 623 | * |
| 624 | * This is safe as we are protected by the hash bucket lock ! |
| 625 | */ |
| 626 | if (unlikely(ownerdied || !(curval & FUTEX_TID_MASK))) { |
| 627 | /* Keep the OWNER_DIED bit */ |
| 628 | newval = (curval & ~FUTEX_TID_MASK) | task_pid_vnr(task); |
| 629 | ownerdied = 0; |
| 630 | lock_taken = 1; |
| 631 | } |
| 632 | |
| 633 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
| 634 | |
| 635 | if (unlikely(curval == -EFAULT)) |
| 636 | return -EFAULT; |
| 637 | if (unlikely(curval != uval)) |
| 638 | goto retry; |
| 639 | |
| 640 | /* |
| 641 | * We took the lock due to owner died take over. |
| 642 | */ |
| 643 | if (unlikely(lock_taken)) |
| 644 | return 1; |
| 645 | |
| 646 | /* |
| 647 | * We dont have the lock. Look up the PI state (or create it if |
| 648 | * we are the first waiter): |
| 649 | */ |
| 650 | ret = lookup_pi_state(uval, hb, key, ps); |
| 651 | |
| 652 | if (unlikely(ret)) { |
| 653 | switch (ret) { |
| 654 | case -ESRCH: |
| 655 | /* |
| 656 | * No owner found for this futex. Check if the |
| 657 | * OWNER_DIED bit is set to figure out whether |
| 658 | * this is a robust futex or not. |
| 659 | */ |
| 660 | if (get_futex_value_locked(&curval, uaddr)) |
| 661 | return -EFAULT; |
| 662 | |
| 663 | /* |
| 664 | * We simply start over in case of a robust |
| 665 | * futex. The code above will take the futex |
| 666 | * and return happy. |
| 667 | */ |
| 668 | if (curval & FUTEX_OWNER_DIED) { |
| 669 | ownerdied = 1; |
| 670 | goto retry; |
| 671 | } |
| 672 | default: |
| 673 | break; |
| 674 | } |
| 675 | } |
| 676 | |
| 677 | return ret; |
| 678 | } |
| 679 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 680 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 681 | * The hash bucket lock must be held when this is called. |
| 682 | * Afterwards, the futex_q must not be accessed. |
| 683 | */ |
| 684 | static void wake_futex(struct futex_q *q) |
| 685 | { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 686 | plist_del(&q->list, &q->list.plist); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 687 | /* |
| 688 | * 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] | 689 | * plist_del() and also before assigning to q->lock_ptr. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 690 | */ |
Darren Hart | 73500ac | 2008-12-17 17:29:56 -0800 | [diff] [blame] | 691 | wake_up(&q->waiter); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 692 | /* |
| 693 | * The waiting task can free the futex_q as soon as this is written, |
| 694 | * without taking any locks. This must come last. |
Andrew Morton | 8e31108 | 2005-12-23 19:54:46 -0800 | [diff] [blame] | 695 | * |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 696 | * A memory barrier is required here to prevent the following store to |
| 697 | * lock_ptr from getting ahead of the wakeup. Clearing the lock at the |
| 698 | * end of wake_up() does not prevent this store from moving. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 699 | */ |
Ralf Baechle | ccdea2f | 2006-12-06 20:40:26 -0800 | [diff] [blame] | 700 | smp_wmb(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 701 | q->lock_ptr = NULL; |
| 702 | } |
| 703 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 704 | static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this) |
| 705 | { |
| 706 | struct task_struct *new_owner; |
| 707 | struct futex_pi_state *pi_state = this->pi_state; |
| 708 | u32 curval, newval; |
| 709 | |
| 710 | if (!pi_state) |
| 711 | return -EINVAL; |
| 712 | |
Ingo Molnar | 21778867 | 2007-03-16 13:38:31 -0800 | [diff] [blame] | 713 | spin_lock(&pi_state->pi_mutex.wait_lock); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 714 | new_owner = rt_mutex_next_owner(&pi_state->pi_mutex); |
| 715 | |
| 716 | /* |
| 717 | * This happens when we have stolen the lock and the original |
| 718 | * pending owner did not enqueue itself back on the rt_mutex. |
| 719 | * Thats not a tragedy. We know that way, that a lock waiter |
| 720 | * is on the fly. We make the futex_q waiter the pending owner. |
| 721 | */ |
| 722 | if (!new_owner) |
| 723 | new_owner = this->task; |
| 724 | |
| 725 | /* |
| 726 | * We pass it to the next owner. (The WAITERS bit is always |
| 727 | * kept enabled while there is PI state around. We must also |
| 728 | * preserve the owner died bit.) |
| 729 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 730 | if (!(uval & FUTEX_OWNER_DIED)) { |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 731 | int ret = 0; |
| 732 | |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 733 | newval = FUTEX_WAITERS | task_pid_vnr(new_owner); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 734 | |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 735 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 736 | |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 737 | if (curval == -EFAULT) |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 738 | ret = -EFAULT; |
Thomas Gleixner | cde898f | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 739 | else if (curval != uval) |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 740 | ret = -EINVAL; |
| 741 | if (ret) { |
| 742 | spin_unlock(&pi_state->pi_mutex.wait_lock); |
| 743 | return ret; |
| 744 | } |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 745 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 746 | |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 747 | spin_lock_irq(&pi_state->owner->pi_lock); |
| 748 | WARN_ON(list_empty(&pi_state->list)); |
| 749 | list_del_init(&pi_state->list); |
| 750 | spin_unlock_irq(&pi_state->owner->pi_lock); |
| 751 | |
| 752 | spin_lock_irq(&new_owner->pi_lock); |
| 753 | WARN_ON(!list_empty(&pi_state->list)); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 754 | list_add(&pi_state->list, &new_owner->pi_state_list); |
| 755 | pi_state->owner = new_owner; |
Ingo Molnar | 627371d | 2006-07-29 05:16:20 +0200 | [diff] [blame] | 756 | spin_unlock_irq(&new_owner->pi_lock); |
| 757 | |
Ingo Molnar | 21778867 | 2007-03-16 13:38:31 -0800 | [diff] [blame] | 758 | spin_unlock(&pi_state->pi_mutex.wait_lock); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 759 | rt_mutex_unlock(&pi_state->pi_mutex); |
| 760 | |
| 761 | return 0; |
| 762 | } |
| 763 | |
| 764 | static int unlock_futex_pi(u32 __user *uaddr, u32 uval) |
| 765 | { |
| 766 | u32 oldval; |
| 767 | |
| 768 | /* |
| 769 | * There is no waiter, so we unlock the futex. The owner died |
| 770 | * bit has not to be preserved here. We are the owner: |
| 771 | */ |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 772 | oldval = cmpxchg_futex_value_locked(uaddr, uval, 0); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 773 | |
| 774 | if (oldval == -EFAULT) |
| 775 | return oldval; |
| 776 | if (oldval != uval) |
| 777 | return -EAGAIN; |
| 778 | |
| 779 | return 0; |
| 780 | } |
| 781 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 782 | /* |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 783 | * Express the locking dependencies for lockdep: |
| 784 | */ |
| 785 | static inline void |
| 786 | double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) |
| 787 | { |
| 788 | if (hb1 <= hb2) { |
| 789 | spin_lock(&hb1->lock); |
| 790 | if (hb1 < hb2) |
| 791 | spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); |
| 792 | } else { /* hb1 > hb2 */ |
| 793 | spin_lock(&hb2->lock); |
| 794 | spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); |
| 795 | } |
| 796 | } |
| 797 | |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 798 | static inline void |
| 799 | double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) |
| 800 | { |
Darren Hart | f061d35 | 2009-03-12 15:11:18 -0700 | [diff] [blame] | 801 | spin_unlock(&hb1->lock); |
Ingo Molnar | 88f502f | 2009-03-13 10:32:07 +0100 | [diff] [blame] | 802 | if (hb1 != hb2) |
| 803 | spin_unlock(&hb2->lock); |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 804 | } |
| 805 | |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 806 | /* |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 807 | * Wake up waiters matching bitset queued on this futex (uaddr). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 808 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 809 | 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] | 810 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 811 | struct futex_hash_bucket *hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 812 | struct futex_q *this, *next; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 813 | struct plist_head *head; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 814 | union futex_key key = FUTEX_KEY_INIT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 815 | int ret; |
| 816 | |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 817 | if (!bitset) |
| 818 | return -EINVAL; |
| 819 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 820 | ret = get_futex_key(uaddr, fshared, &key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 821 | if (unlikely(ret != 0)) |
| 822 | goto out; |
| 823 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 824 | hb = hash_futex(&key); |
| 825 | spin_lock(&hb->lock); |
| 826 | head = &hb->chain; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 827 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 828 | plist_for_each_entry_safe(this, next, head, list) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 829 | if (match_futex (&this->key, &key)) { |
Ingo Molnar | ed6f7b1 | 2006-07-01 04:35:46 -0700 | [diff] [blame] | 830 | if (this->pi_state) { |
| 831 | ret = -EINVAL; |
| 832 | break; |
| 833 | } |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 834 | |
| 835 | /* Check if one of the bits is set in both bitsets */ |
| 836 | if (!(this->bitset & bitset)) |
| 837 | continue; |
| 838 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 839 | wake_futex(this); |
| 840 | if (++ret >= nr_wake) |
| 841 | break; |
| 842 | } |
| 843 | } |
| 844 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 845 | spin_unlock(&hb->lock); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 846 | put_futex_key(fshared, &key); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 847 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 848 | return ret; |
| 849 | } |
| 850 | |
| 851 | /* |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 852 | * Wake up all waiters hashed on the physical page that is mapped |
| 853 | * to this virtual address: |
| 854 | */ |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 855 | static int |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 856 | futex_wake_op(u32 __user *uaddr1, int fshared, u32 __user *uaddr2, |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 857 | int nr_wake, int nr_wake2, int op) |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 858 | { |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 859 | union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 860 | struct futex_hash_bucket *hb1, *hb2; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 861 | struct plist_head *head; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 862 | struct futex_q *this, *next; |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 863 | int ret, op_ret; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 864 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 865 | retry: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 866 | ret = get_futex_key(uaddr1, fshared, &key1); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 867 | if (unlikely(ret != 0)) |
| 868 | goto out; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 869 | ret = get_futex_key(uaddr2, fshared, &key2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 870 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 871 | goto out_put_key1; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 872 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 873 | hb1 = hash_futex(&key1); |
| 874 | hb2 = hash_futex(&key2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 875 | |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 876 | double_lock_hb(hb1, hb2); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 877 | retry_private: |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 878 | op_ret = futex_atomic_op_inuser(op, uaddr2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 879 | if (unlikely(op_ret < 0)) { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 880 | u32 dummy; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 881 | |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 882 | double_unlock_hb(hb1, hb2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 883 | |
David Howells | 7ee1dd3 | 2006-01-06 00:11:44 -0800 | [diff] [blame] | 884 | #ifndef CONFIG_MMU |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 885 | /* |
| 886 | * we don't get EFAULT from MMU faults if we don't have an MMU, |
| 887 | * but we might get them from range checking |
| 888 | */ |
David Howells | 7ee1dd3 | 2006-01-06 00:11:44 -0800 | [diff] [blame] | 889 | ret = op_ret; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 890 | goto out_put_keys; |
David Howells | 7ee1dd3 | 2006-01-06 00:11:44 -0800 | [diff] [blame] | 891 | #endif |
| 892 | |
David Gibson | 796f8d9 | 2005-11-07 00:59:33 -0800 | [diff] [blame] | 893 | if (unlikely(op_ret != -EFAULT)) { |
| 894 | ret = op_ret; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 895 | goto out_put_keys; |
David Gibson | 796f8d9 | 2005-11-07 00:59:33 -0800 | [diff] [blame] | 896 | } |
| 897 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 898 | ret = get_user(dummy, uaddr2); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 899 | if (ret) |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 900 | goto out_put_keys; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 901 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 902 | if (!fshared) |
| 903 | goto retry_private; |
| 904 | |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 905 | put_futex_key(fshared, &key2); |
| 906 | put_futex_key(fshared, &key1); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 907 | goto retry; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 908 | } |
| 909 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 910 | head = &hb1->chain; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 911 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 912 | plist_for_each_entry_safe(this, next, head, list) { |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 913 | if (match_futex (&this->key, &key1)) { |
| 914 | wake_futex(this); |
| 915 | if (++ret >= nr_wake) |
| 916 | break; |
| 917 | } |
| 918 | } |
| 919 | |
| 920 | if (op_ret > 0) { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 921 | head = &hb2->chain; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 922 | |
| 923 | op_ret = 0; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 924 | plist_for_each_entry_safe(this, next, head, list) { |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 925 | if (match_futex (&this->key, &key2)) { |
| 926 | wake_futex(this); |
| 927 | if (++op_ret >= nr_wake2) |
| 928 | break; |
| 929 | } |
| 930 | } |
| 931 | ret += op_ret; |
| 932 | } |
| 933 | |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 934 | double_unlock_hb(hb1, hb2); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 935 | out_put_keys: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 936 | put_futex_key(fshared, &key2); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 937 | out_put_key1: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 938 | put_futex_key(fshared, &key1); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 939 | out: |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 940 | return ret; |
| 941 | } |
| 942 | |
| 943 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 944 | * Requeue all waiters hashed on one physical page to another |
| 945 | * physical page. |
| 946 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 947 | static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2, |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 948 | int nr_wake, int nr_requeue, u32 *cmpval) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 949 | { |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 950 | union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 951 | struct futex_hash_bucket *hb1, *hb2; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 952 | struct plist_head *head1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 953 | struct futex_q *this, *next; |
| 954 | int ret, drop_count = 0; |
| 955 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 956 | retry: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 957 | ret = get_futex_key(uaddr1, fshared, &key1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 958 | if (unlikely(ret != 0)) |
| 959 | goto out; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 960 | ret = get_futex_key(uaddr2, fshared, &key2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 961 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 962 | goto out_put_key1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 963 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 964 | hb1 = hash_futex(&key1); |
| 965 | hb2 = hash_futex(&key2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 966 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 967 | retry_private: |
Ingo Molnar | 8b8f319 | 2006-07-03 00:25:05 -0700 | [diff] [blame] | 968 | double_lock_hb(hb1, hb2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 969 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 970 | if (likely(cmpval != NULL)) { |
| 971 | u32 curval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 972 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 973 | ret = get_futex_value_locked(&curval, uaddr1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 974 | |
| 975 | if (unlikely(ret)) { |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 976 | double_unlock_hb(hb1, hb2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 977 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 978 | ret = get_user(curval, uaddr1); |
| 979 | if (ret) |
| 980 | goto out_put_keys; |
| 981 | |
| 982 | if (!fshared) |
| 983 | goto retry_private; |
| 984 | |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 985 | put_futex_key(fshared, &key2); |
| 986 | put_futex_key(fshared, &key1); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 987 | goto retry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 988 | } |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 989 | if (curval != *cmpval) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 990 | ret = -EAGAIN; |
| 991 | goto out_unlock; |
| 992 | } |
| 993 | } |
| 994 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 995 | head1 = &hb1->chain; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 996 | plist_for_each_entry_safe(this, next, head1, list) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 997 | if (!match_futex (&this->key, &key1)) |
| 998 | continue; |
| 999 | if (++ret <= nr_wake) { |
| 1000 | wake_futex(this); |
| 1001 | } else { |
Sebastien Dugue | 59e0e0a | 2006-06-27 02:55:03 -0700 | [diff] [blame] | 1002 | /* |
| 1003 | * If key1 and key2 hash to the same bucket, no need to |
| 1004 | * requeue. |
| 1005 | */ |
| 1006 | if (likely(head1 != &hb2->chain)) { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1007 | plist_del(&this->list, &hb1->chain); |
| 1008 | plist_add(&this->list, &hb2->chain); |
Sebastien Dugue | 59e0e0a | 2006-06-27 02:55:03 -0700 | [diff] [blame] | 1009 | this->lock_ptr = &hb2->lock; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1010 | #ifdef CONFIG_DEBUG_PI_LIST |
| 1011 | this->list.plist.lock = &hb2->lock; |
| 1012 | #endif |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1013 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1014 | this->key = key2; |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1015 | get_futex_key_refs(&key2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1016 | drop_count++; |
| 1017 | |
| 1018 | if (ret - nr_wake >= nr_requeue) |
| 1019 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1020 | } |
| 1021 | } |
| 1022 | |
| 1023 | out_unlock: |
Darren Hart | 5eb3dc6 | 2009-03-12 00:55:52 -0700 | [diff] [blame] | 1024 | double_unlock_hb(hb1, hb2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1025 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1026 | /* drop_futex_key_refs() must be called outside the spinlocks. */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1027 | while (--drop_count >= 0) |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1028 | drop_futex_key_refs(&key1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1029 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1030 | out_put_keys: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1031 | put_futex_key(fshared, &key2); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1032 | out_put_key1: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1033 | put_futex_key(fshared, &key1); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1034 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1035 | return ret; |
| 1036 | } |
| 1037 | |
| 1038 | /* The key must be already stored in q->key. */ |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1039 | static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1040 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1041 | struct futex_hash_bucket *hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1042 | |
Darren Hart | 73500ac | 2008-12-17 17:29:56 -0800 | [diff] [blame] | 1043 | init_waitqueue_head(&q->waiter); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1044 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1045 | get_futex_key_refs(&q->key); |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1046 | hb = hash_futex(&q->key); |
| 1047 | q->lock_ptr = &hb->lock; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1048 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1049 | spin_lock(&hb->lock); |
| 1050 | return hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1051 | } |
| 1052 | |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1053 | 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] | 1054 | { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1055 | int prio; |
| 1056 | |
| 1057 | /* |
| 1058 | * The priority used to register this element is |
| 1059 | * - either the real thread-priority for the real-time threads |
| 1060 | * (i.e. threads with a priority lower than MAX_RT_PRIO) |
| 1061 | * - or MAX_RT_PRIO for non-RT threads. |
| 1062 | * Thus, all RT-threads are woken first in priority order, and |
| 1063 | * the others are woken last, in FIFO order. |
| 1064 | */ |
| 1065 | prio = min(current->normal_prio, MAX_RT_PRIO); |
| 1066 | |
| 1067 | plist_node_init(&q->list, prio); |
| 1068 | #ifdef CONFIG_DEBUG_PI_LIST |
| 1069 | q->list.plist.lock = &hb->lock; |
| 1070 | #endif |
| 1071 | plist_add(&q->list, &hb->chain); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1072 | q->task = current; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1073 | spin_unlock(&hb->lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1074 | } |
| 1075 | |
| 1076 | static inline void |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1077 | queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1078 | { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1079 | spin_unlock(&hb->lock); |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1080 | drop_futex_key_refs(&q->key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1081 | } |
| 1082 | |
| 1083 | /* |
| 1084 | * queue_me and unqueue_me must be called as a pair, each |
| 1085 | * exactly once. They are called with the hashed spinlock held. |
| 1086 | */ |
| 1087 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1088 | /* Return 1 if we were still queued (ie. 0 means we were woken) */ |
| 1089 | static int unqueue_me(struct futex_q *q) |
| 1090 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1091 | spinlock_t *lock_ptr; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1092 | int ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1093 | |
| 1094 | /* 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] | 1095 | retry: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1096 | lock_ptr = q->lock_ptr; |
Christian Borntraeger | e91467e | 2006-08-05 12:13:52 -0700 | [diff] [blame] | 1097 | barrier(); |
Stephen Hemminger | c80544d | 2007-10-18 03:07:05 -0700 | [diff] [blame] | 1098 | if (lock_ptr != NULL) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1099 | spin_lock(lock_ptr); |
| 1100 | /* |
| 1101 | * q->lock_ptr can change between reading it and |
| 1102 | * spin_lock(), causing us to take the wrong lock. This |
| 1103 | * corrects the race condition. |
| 1104 | * |
| 1105 | * Reasoning goes like this: if we have the wrong lock, |
| 1106 | * q->lock_ptr must have changed (maybe several times) |
| 1107 | * between reading it and the spin_lock(). It can |
| 1108 | * change again after the spin_lock() but only if it was |
| 1109 | * already changed before the spin_lock(). It cannot, |
| 1110 | * however, change back to the original value. Therefore |
| 1111 | * we can detect whether we acquired the correct lock. |
| 1112 | */ |
| 1113 | if (unlikely(lock_ptr != q->lock_ptr)) { |
| 1114 | spin_unlock(lock_ptr); |
| 1115 | goto retry; |
| 1116 | } |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1117 | WARN_ON(plist_node_empty(&q->list)); |
| 1118 | plist_del(&q->list, &q->list.plist); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1119 | |
| 1120 | BUG_ON(q->pi_state); |
| 1121 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1122 | spin_unlock(lock_ptr); |
| 1123 | ret = 1; |
| 1124 | } |
| 1125 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1126 | drop_futex_key_refs(&q->key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1127 | return ret; |
| 1128 | } |
| 1129 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1130 | /* |
| 1131 | * PI futexes can not be requeued and must remove themself from the |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1132 | * hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry |
| 1133 | * and dropped here. |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1134 | */ |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1135 | static void unqueue_me_pi(struct futex_q *q) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1136 | { |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1137 | WARN_ON(plist_node_empty(&q->list)); |
| 1138 | plist_del(&q->list, &q->list.plist); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1139 | |
| 1140 | BUG_ON(!q->pi_state); |
| 1141 | free_pi_state(q->pi_state); |
| 1142 | q->pi_state = NULL; |
| 1143 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1144 | spin_unlock(q->lock_ptr); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1145 | |
Rusty Russell | 9adef58 | 2007-05-08 00:26:42 -0700 | [diff] [blame] | 1146 | drop_futex_key_refs(&q->key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1147 | } |
| 1148 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1149 | /* |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1150 | * Fixup the pi_state owner with the new owner. |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1151 | * |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1152 | * Must be called with hash bucket lock held and mm->sem held for non |
| 1153 | * private futexes. |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1154 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1155 | 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] | 1156 | struct task_struct *newowner, int fshared) |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1157 | { |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1158 | u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1159 | struct futex_pi_state *pi_state = q->pi_state; |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1160 | struct task_struct *oldowner = pi_state->owner; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1161 | u32 uval, curval, newval; |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1162 | int ret; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1163 | |
| 1164 | /* Owner died? */ |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1165 | if (!pi_state->owner) |
| 1166 | newtid |= FUTEX_OWNER_DIED; |
| 1167 | |
| 1168 | /* |
| 1169 | * We are here either because we stole the rtmutex from the |
| 1170 | * pending owner or we are the pending owner which failed to |
| 1171 | * get the rtmutex. We have to replace the pending owner TID |
| 1172 | * in the user space variable. This must be atomic as we have |
| 1173 | * to preserve the owner died bit here. |
| 1174 | * |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 1175 | * Note: We write the user space value _before_ changing the pi_state |
| 1176 | * because we can fault here. Imagine swapped out pages or a fork |
| 1177 | * that marked all the anonymous memory readonly for cow. |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1178 | * |
| 1179 | * Modifying pi_state _before_ the user space value would |
| 1180 | * leave the pi_state in an inconsistent state when we fault |
| 1181 | * here, because we need to drop the hash bucket lock to |
| 1182 | * handle the fault. This might be observed in the PID check |
| 1183 | * in lookup_pi_state. |
| 1184 | */ |
| 1185 | retry: |
| 1186 | if (get_futex_value_locked(&uval, uaddr)) |
| 1187 | goto handle_fault; |
| 1188 | |
| 1189 | while (1) { |
| 1190 | newval = (uval & FUTEX_OWNER_DIED) | newtid; |
| 1191 | |
| 1192 | curval = cmpxchg_futex_value_locked(uaddr, uval, newval); |
| 1193 | |
| 1194 | if (curval == -EFAULT) |
| 1195 | goto handle_fault; |
| 1196 | if (curval == uval) |
| 1197 | break; |
| 1198 | uval = curval; |
| 1199 | } |
| 1200 | |
| 1201 | /* |
| 1202 | * We fixed up user space. Now we need to fix the pi_state |
| 1203 | * itself. |
| 1204 | */ |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1205 | if (pi_state->owner != NULL) { |
| 1206 | spin_lock_irq(&pi_state->owner->pi_lock); |
| 1207 | WARN_ON(list_empty(&pi_state->list)); |
| 1208 | list_del_init(&pi_state->list); |
| 1209 | spin_unlock_irq(&pi_state->owner->pi_lock); |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1210 | } |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1211 | |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1212 | pi_state->owner = newowner; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1213 | |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1214 | spin_lock_irq(&newowner->pi_lock); |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1215 | WARN_ON(!list_empty(&pi_state->list)); |
Thomas Gleixner | cdf71a1 | 2008-01-08 19:47:38 +0100 | [diff] [blame] | 1216 | list_add(&pi_state->list, &newowner->pi_state_list); |
| 1217 | spin_unlock_irq(&newowner->pi_lock); |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1218 | return 0; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1219 | |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1220 | /* |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1221 | * To handle the page fault we need to drop the hash bucket |
| 1222 | * lock here. That gives the other task (either the pending |
| 1223 | * owner itself or the task which stole the rtmutex) the |
| 1224 | * chance to try the fixup of the pi_state. So once we are |
| 1225 | * back from handling the fault we need to check the pi_state |
| 1226 | * after reacquiring the hash bucket lock and before trying to |
| 1227 | * do another fixup. When the fixup has been done already we |
| 1228 | * simply return. |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1229 | */ |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1230 | handle_fault: |
| 1231 | spin_unlock(q->lock_ptr); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1232 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1233 | ret = get_user(uval, uaddr); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1234 | |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1235 | spin_lock(q->lock_ptr); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1236 | |
Thomas Gleixner | 1b7558e | 2008-06-23 11:21:58 +0200 | [diff] [blame] | 1237 | /* |
| 1238 | * Check if someone else fixed it for us: |
| 1239 | */ |
| 1240 | if (pi_state->owner != oldowner) |
| 1241 | return 0; |
| 1242 | |
| 1243 | if (ret) |
| 1244 | return ret; |
| 1245 | |
| 1246 | goto retry; |
Pierre Peiffer | d0aa7a7 | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1247 | } |
| 1248 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1249 | /* |
| 1250 | * In case we must use restart_block to restart a futex_wait, |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1251 | * we encode in the 'flags' shared capability |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1252 | */ |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1253 | #define FLAGS_SHARED 0x01 |
| 1254 | #define FLAGS_CLOCKRT 0x02 |
Darren Hart | a72188d | 2009-04-03 13:40:22 -0700 | [diff] [blame^] | 1255 | #define FLAGS_HAS_TIMEOUT 0x04 |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1256 | |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1257 | static long futex_wait_restart(struct restart_block *restart); |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1258 | |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1259 | /** |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1260 | * fixup_owner() - Post lock pi_state and corner case management |
| 1261 | * @uaddr: user address of the futex |
| 1262 | * @fshared: whether the futex is shared (1) or not (0) |
| 1263 | * @q: futex_q (contains pi_state and access to the rt_mutex) |
| 1264 | * @locked: if the attempt to take the rt_mutex succeeded (1) or not (0) |
| 1265 | * |
| 1266 | * After attempting to lock an rt_mutex, this function is called to cleanup |
| 1267 | * the pi_state owner as well as handle race conditions that may allow us to |
| 1268 | * acquire the lock. Must be called with the hb lock held. |
| 1269 | * |
| 1270 | * Returns: |
| 1271 | * 1 - success, lock taken |
| 1272 | * 0 - success, lock not taken |
| 1273 | * <0 - on error (-EFAULT) |
| 1274 | */ |
| 1275 | static int fixup_owner(u32 __user *uaddr, int fshared, struct futex_q *q, |
| 1276 | int locked) |
| 1277 | { |
| 1278 | struct task_struct *owner; |
| 1279 | int ret = 0; |
| 1280 | |
| 1281 | if (locked) { |
| 1282 | /* |
| 1283 | * Got the lock. We might not be the anticipated owner if we |
| 1284 | * did a lock-steal - fix up the PI-state in that case: |
| 1285 | */ |
| 1286 | if (q->pi_state->owner != current) |
| 1287 | ret = fixup_pi_state_owner(uaddr, q, current, fshared); |
| 1288 | goto out; |
| 1289 | } |
| 1290 | |
| 1291 | /* |
| 1292 | * Catch the rare case, where the lock was released when we were on the |
| 1293 | * way back before we locked the hash bucket. |
| 1294 | */ |
| 1295 | if (q->pi_state->owner == current) { |
| 1296 | /* |
| 1297 | * Try to get the rt_mutex now. This might fail as some other |
| 1298 | * task acquired the rt_mutex after we removed ourself from the |
| 1299 | * rt_mutex waiters list. |
| 1300 | */ |
| 1301 | if (rt_mutex_trylock(&q->pi_state->pi_mutex)) { |
| 1302 | locked = 1; |
| 1303 | goto out; |
| 1304 | } |
| 1305 | |
| 1306 | /* |
| 1307 | * pi_state is incorrect, some other task did a lock steal and |
| 1308 | * we returned due to timeout or signal without taking the |
| 1309 | * rt_mutex. Too late. We can access the rt_mutex_owner without |
| 1310 | * locking, as the other task is now blocked on the hash bucket |
| 1311 | * lock. Fix the state up. |
| 1312 | */ |
| 1313 | owner = rt_mutex_owner(&q->pi_state->pi_mutex); |
| 1314 | ret = fixup_pi_state_owner(uaddr, q, owner, fshared); |
| 1315 | goto out; |
| 1316 | } |
| 1317 | |
| 1318 | /* |
| 1319 | * Paranoia check. If we did not take the lock, then we should not be |
| 1320 | * the owner, nor the pending owner, of the rt_mutex. |
| 1321 | */ |
| 1322 | if (rt_mutex_owner(&q->pi_state->pi_mutex) == current) |
| 1323 | printk(KERN_ERR "fixup_owner: ret = %d pi-mutex: %p " |
| 1324 | "pi-state %p\n", ret, |
| 1325 | q->pi_state->pi_mutex.owner, |
| 1326 | q->pi_state->owner); |
| 1327 | |
| 1328 | out: |
| 1329 | return ret ? ret : locked; |
| 1330 | } |
| 1331 | |
| 1332 | /** |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1333 | * futex_wait_queue_me() - queue_me() and wait for wakeup, timeout, or signal |
| 1334 | * @hb: the futex hash bucket, must be locked by the caller |
| 1335 | * @q: the futex_q to queue up on |
| 1336 | * @timeout: the prepared hrtimer_sleeper, or null for no timeout |
| 1337 | * @wait: the wait_queue to add to the futex_q after queueing in the hb |
| 1338 | */ |
| 1339 | static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q, |
| 1340 | struct hrtimer_sleeper *timeout, |
| 1341 | wait_queue_t *wait) |
| 1342 | { |
| 1343 | queue_me(q, hb); |
| 1344 | |
| 1345 | /* |
| 1346 | * There might have been scheduling since the queue_me(), as we |
| 1347 | * cannot hold a spinlock across the get_user() in case it |
| 1348 | * faults, and we cannot just set TASK_INTERRUPTIBLE state when |
| 1349 | * queueing ourselves into the futex hash. This code thus has to |
| 1350 | * rely on the futex_wake() code removing us from hash when it |
| 1351 | * wakes us up. |
| 1352 | */ |
| 1353 | |
| 1354 | /* add_wait_queue is the barrier after __set_current_state. */ |
| 1355 | __set_current_state(TASK_INTERRUPTIBLE); |
| 1356 | |
| 1357 | /* |
| 1358 | * Add current as the futex_q waiter. We don't remove ourselves from |
| 1359 | * the wait_queue because we are the only user of it. |
| 1360 | */ |
| 1361 | add_wait_queue(&q->waiter, wait); |
| 1362 | |
| 1363 | /* Arm the timer */ |
| 1364 | if (timeout) { |
| 1365 | hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS); |
| 1366 | if (!hrtimer_active(&timeout->timer)) |
| 1367 | timeout->task = NULL; |
| 1368 | } |
| 1369 | |
| 1370 | /* |
| 1371 | * !plist_node_empty() is safe here without any lock. |
| 1372 | * q.lock_ptr != 0 is not safe, because of ordering against wakeup. |
| 1373 | */ |
| 1374 | if (likely(!plist_node_empty(&q->list))) { |
| 1375 | /* |
| 1376 | * If the timer has already expired, current will already be |
| 1377 | * flagged for rescheduling. Only call schedule if there |
| 1378 | * is no timeout, or if it has yet to expire. |
| 1379 | */ |
| 1380 | if (!timeout || timeout->task) |
| 1381 | schedule(); |
| 1382 | } |
| 1383 | __set_current_state(TASK_RUNNING); |
| 1384 | } |
| 1385 | |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1386 | static int futex_wait(u32 __user *uaddr, int fshared, |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1387 | u32 val, ktime_t *abs_time, u32 bitset, int clockrt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1388 | { |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1389 | struct hrtimer_sleeper timeout, *to = NULL; |
| 1390 | DECLARE_WAITQUEUE(wait, current); |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1391 | struct restart_block *restart; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1392 | struct futex_hash_bucket *hb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1393 | struct futex_q q; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1394 | u32 uval; |
| 1395 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1396 | |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1397 | if (!bitset) |
| 1398 | return -EINVAL; |
| 1399 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1400 | q.pi_state = NULL; |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1401 | q.bitset = bitset; |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1402 | |
| 1403 | if (abs_time) { |
| 1404 | to = &timeout; |
| 1405 | |
| 1406 | hrtimer_init_on_stack(&to->timer, clockrt ? CLOCK_REALTIME : |
| 1407 | CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 1408 | hrtimer_init_sleeper(to, current); |
| 1409 | hrtimer_set_expires_range_ns(&to->timer, *abs_time, |
| 1410 | current->timer_slack_ns); |
| 1411 | } |
| 1412 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1413 | retry: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1414 | q.key = FUTEX_KEY_INIT; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1415 | ret = get_futex_key(uaddr, fshared, &q.key); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1416 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1417 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1418 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1419 | retry_private: |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1420 | hb = queue_lock(&q); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1421 | |
| 1422 | /* |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 1423 | * Access the page AFTER the hash-bucket is locked. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1424 | * Order is important: |
| 1425 | * |
| 1426 | * Userspace waiter: val = var; if (cond(val)) futex_wait(&var, val); |
| 1427 | * Userspace waker: if (cond(var)) { var = new; futex_wake(&var); } |
| 1428 | * |
| 1429 | * The basic logical guarantee of a futex is that it blocks ONLY |
| 1430 | * if cond(var) is known to be true at the time of blocking, for |
| 1431 | * any cond. If we queued after testing *uaddr, that would open |
| 1432 | * a race condition where we could block indefinitely with |
| 1433 | * cond(var) false, which would violate the guarantee. |
| 1434 | * |
| 1435 | * A consequence is that futex_wait() can return zero and absorb |
| 1436 | * a wakeup when *uaddr != val on entry to the syscall. This is |
| 1437 | * rare, but normal. |
| 1438 | * |
Darren Hart | b2d0994 | 2009-03-12 00:55:37 -0700 | [diff] [blame] | 1439 | * For shared futexes, we hold the mmap semaphore, so the mapping |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1440 | * cannot have changed since we looked it up in get_futex_key. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1441 | */ |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1442 | ret = get_futex_value_locked(&uval, uaddr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1443 | |
| 1444 | if (unlikely(ret)) { |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1445 | queue_unlock(&q, hb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1446 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1447 | ret = get_user(uval, uaddr); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1448 | if (ret) |
| 1449 | goto out_put_key; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1450 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1451 | if (!fshared) |
| 1452 | goto retry_private; |
| 1453 | |
| 1454 | put_futex_key(fshared, &q.key); |
| 1455 | goto retry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1456 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1457 | ret = -EWOULDBLOCK; |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1458 | |
| 1459 | /* Only actually queue if *uaddr contained val. */ |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1460 | if (unlikely(uval != val)) { |
| 1461 | queue_unlock(&q, hb); |
| 1462 | goto out_put_key; |
| 1463 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1464 | |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1465 | /* queue_me and wait for wakeup, timeout, or a signal. */ |
| 1466 | futex_wait_queue_me(hb, &q, to, &wait); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1467 | |
| 1468 | /* If we were woken (and unqueued), we succeeded, whatever. */ |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1469 | ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1470 | if (!unqueue_me(&q)) |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1471 | goto out_put_key; |
| 1472 | ret = -ETIMEDOUT; |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1473 | if (to && !to->task) |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1474 | goto out_put_key; |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1475 | |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 1476 | /* |
| 1477 | * We expect signal_pending(current), but another thread may |
| 1478 | * have handled it for us already. |
| 1479 | */ |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1480 | ret = -ERESTARTSYS; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1481 | if (!abs_time) |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1482 | goto out_put_key; |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1483 | |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1484 | restart = ¤t_thread_info()->restart_block; |
| 1485 | restart->fn = futex_wait_restart; |
| 1486 | restart->futex.uaddr = (u32 *)uaddr; |
| 1487 | restart->futex.val = val; |
| 1488 | restart->futex.time = abs_time->tv64; |
| 1489 | restart->futex.bitset = bitset; |
Darren Hart | a72188d | 2009-04-03 13:40:22 -0700 | [diff] [blame^] | 1490 | restart->futex.flags = FLAGS_HAS_TIMEOUT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1491 | |
Peter Zijlstra | 2fff78c | 2009-02-11 18:10:10 +0100 | [diff] [blame] | 1492 | if (fshared) |
| 1493 | restart->futex.flags |= FLAGS_SHARED; |
| 1494 | if (clockrt) |
| 1495 | restart->futex.flags |= FLAGS_CLOCKRT; |
| 1496 | |
| 1497 | ret = -ERESTART_RESTARTBLOCK; |
| 1498 | |
| 1499 | out_put_key: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1500 | put_futex_key(fshared, &q.key); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1501 | out: |
Darren Hart | ca5f952 | 2009-04-03 13:39:33 -0700 | [diff] [blame] | 1502 | if (to) { |
| 1503 | hrtimer_cancel(&to->timer); |
| 1504 | destroy_hrtimer_on_stack(&to->timer); |
| 1505 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1506 | return ret; |
| 1507 | } |
| 1508 | |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1509 | |
| 1510 | static long futex_wait_restart(struct restart_block *restart) |
| 1511 | { |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1512 | u32 __user *uaddr = (u32 __user *)restart->futex.uaddr; |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1513 | int fshared = 0; |
Darren Hart | a72188d | 2009-04-03 13:40:22 -0700 | [diff] [blame^] | 1514 | ktime_t t, *tp = NULL; |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1515 | |
Darren Hart | a72188d | 2009-04-03 13:40:22 -0700 | [diff] [blame^] | 1516 | if (restart->futex.flags & FLAGS_HAS_TIMEOUT) { |
| 1517 | t.tv64 = restart->futex.time; |
| 1518 | tp = &t; |
| 1519 | } |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1520 | restart->fn = do_no_restart_syscall; |
Steven Rostedt | ce6bd42 | 2007-12-05 15:46:09 +0100 | [diff] [blame] | 1521 | if (restart->futex.flags & FLAGS_SHARED) |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1522 | fshared = 1; |
Darren Hart | a72188d | 2009-04-03 13:40:22 -0700 | [diff] [blame^] | 1523 | return (long)futex_wait(uaddr, fshared, restart->futex.val, tp, |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1524 | restart->futex.bitset, |
| 1525 | restart->futex.flags & FLAGS_CLOCKRT); |
Nick Piggin | 72c1bbf | 2007-05-08 00:26:43 -0700 | [diff] [blame] | 1526 | } |
| 1527 | |
| 1528 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1529 | /* |
| 1530 | * Userspace tried a 0 -> TID atomic transition of the futex value |
| 1531 | * and failed. The kernel side here does the whole locking operation: |
| 1532 | * if there are waiters then it will block, it does PI, etc. (Due to |
| 1533 | * races the kernel might see a 0 value of the futex too.) |
| 1534 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1535 | static int futex_lock_pi(u32 __user *uaddr, int fshared, |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1536 | int detect, ktime_t *time, int trylock) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1537 | { |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1538 | struct hrtimer_sleeper timeout, *to = NULL; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1539 | struct futex_hash_bucket *hb; |
Darren Hart | 1a52084 | 2009-04-03 13:39:52 -0700 | [diff] [blame] | 1540 | u32 uval; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1541 | struct futex_q q; |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1542 | int res, ret; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1543 | |
| 1544 | if (refill_pi_state_cache()) |
| 1545 | return -ENOMEM; |
| 1546 | |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1547 | if (time) { |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1548 | to = &timeout; |
Thomas Gleixner | 237fc6e | 2008-04-30 00:55:04 -0700 | [diff] [blame] | 1549 | hrtimer_init_on_stack(&to->timer, CLOCK_REALTIME, |
| 1550 | HRTIMER_MODE_ABS); |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1551 | hrtimer_init_sleeper(to, current); |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 1552 | hrtimer_set_expires(&to->timer, *time); |
Thomas Gleixner | c5780e9 | 2006-09-08 09:47:15 -0700 | [diff] [blame] | 1553 | } |
| 1554 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1555 | q.pi_state = NULL; |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1556 | retry: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1557 | q.key = FUTEX_KEY_INIT; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1558 | ret = get_futex_key(uaddr, fshared, &q.key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1559 | if (unlikely(ret != 0)) |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1560 | goto out; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1561 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1562 | retry_private: |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1563 | hb = queue_lock(&q); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1564 | |
Darren Hart | 1a52084 | 2009-04-03 13:39:52 -0700 | [diff] [blame] | 1565 | ret = futex_lock_pi_atomic(uaddr, hb, &q.key, &q.pi_state, current); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1566 | if (unlikely(ret)) { |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1567 | switch (ret) { |
Darren Hart | 1a52084 | 2009-04-03 13:39:52 -0700 | [diff] [blame] | 1568 | case 1: |
| 1569 | /* We got the lock. */ |
| 1570 | ret = 0; |
| 1571 | goto out_unlock_put_key; |
| 1572 | case -EFAULT: |
| 1573 | goto uaddr_faulted; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1574 | case -EAGAIN: |
| 1575 | /* |
| 1576 | * Task is exiting and we just wait for the |
| 1577 | * exit to complete. |
| 1578 | */ |
| 1579 | queue_unlock(&q, hb); |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 1580 | put_futex_key(fshared, &q.key); |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1581 | cond_resched(); |
| 1582 | goto retry; |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1583 | default: |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1584 | goto out_unlock_put_key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1585 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1586 | } |
| 1587 | |
| 1588 | /* |
| 1589 | * Only actually queue now that the atomic ops are done: |
| 1590 | */ |
Eric Sesterhenn | 82af7ac | 2008-01-25 10:40:46 +0100 | [diff] [blame] | 1591 | queue_me(&q, hb); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1592 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1593 | WARN_ON(!q.pi_state); |
| 1594 | /* |
| 1595 | * Block on the PI mutex: |
| 1596 | */ |
| 1597 | if (!trylock) |
| 1598 | ret = rt_mutex_timed_lock(&q.pi_state->pi_mutex, to, 1); |
| 1599 | else { |
| 1600 | ret = rt_mutex_trylock(&q.pi_state->pi_mutex); |
| 1601 | /* Fixup the trylock return value: */ |
| 1602 | ret = ret ? 0 : -EWOULDBLOCK; |
| 1603 | } |
| 1604 | |
Vernon Mauery | a99e4e4 | 2006-07-01 04:35:42 -0700 | [diff] [blame] | 1605 | spin_lock(q.lock_ptr); |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1606 | /* |
| 1607 | * Fixup the pi_state owner and possibly acquire the lock if we |
| 1608 | * haven't already. |
| 1609 | */ |
| 1610 | res = fixup_owner(uaddr, fshared, &q, !ret); |
| 1611 | /* |
| 1612 | * If fixup_owner() returned an error, proprogate that. If it acquired |
| 1613 | * the lock, clear our -ETIMEDOUT or -EINTR. |
| 1614 | */ |
| 1615 | if (res) |
| 1616 | ret = (res < 0) ? res : 0; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1617 | |
Darren Hart | e8f6386 | 2009-03-12 00:56:06 -0700 | [diff] [blame] | 1618 | /* |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1619 | * If fixup_owner() faulted and was unable to handle the fault, unlock |
| 1620 | * it and return the fault to userspace. |
Darren Hart | e8f6386 | 2009-03-12 00:56:06 -0700 | [diff] [blame] | 1621 | */ |
| 1622 | if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current)) |
| 1623 | rt_mutex_unlock(&q.pi_state->pi_mutex); |
| 1624 | |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1625 | /* Unqueue and drop the lock */ |
| 1626 | unqueue_me_pi(&q); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1627 | |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1628 | goto out; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1629 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1630 | out_unlock_put_key: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1631 | queue_unlock(&q, hb); |
| 1632 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1633 | out_put_key: |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1634 | put_futex_key(fshared, &q.key); |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1635 | out: |
Thomas Gleixner | 237fc6e | 2008-04-30 00:55:04 -0700 | [diff] [blame] | 1636 | if (to) |
| 1637 | destroy_hrtimer_on_stack(&to->timer); |
Darren Hart | dd97399 | 2009-04-03 13:40:02 -0700 | [diff] [blame] | 1638 | return ret != -EINTR ? ret : -ERESTARTNOINTR; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1639 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1640 | uaddr_faulted: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1641 | /* |
Darren Hart | b568636 | 2008-12-18 15:06:34 -0800 | [diff] [blame] | 1642 | * We have to r/w *(int __user *)uaddr, and we have to modify it |
| 1643 | * atomically. Therefore, if we continue to fault after get_user() |
| 1644 | * below, we need to handle the fault ourselves, while still holding |
| 1645 | * the mmap_sem. This can occur if the uaddr is under contention as |
| 1646 | * 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] | 1647 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1648 | queue_unlock(&q, hb); |
| 1649 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1650 | ret = get_user(uval, uaddr); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1651 | if (ret) |
| 1652 | goto out_put_key; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1653 | |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1654 | if (!fshared) |
| 1655 | goto retry_private; |
| 1656 | |
| 1657 | put_futex_key(fshared, &q.key); |
| 1658 | goto retry; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1659 | } |
| 1660 | |
Darren Hart | de87fcc | 2009-03-12 00:55:46 -0700 | [diff] [blame] | 1661 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1662 | /* |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1663 | * Userspace attempted a TID -> 0 atomic transition, and failed. |
| 1664 | * This is the in-kernel slowpath: we look up the PI state (if any), |
| 1665 | * and do the rt-mutex unlock. |
| 1666 | */ |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1667 | static int futex_unlock_pi(u32 __user *uaddr, int fshared) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1668 | { |
| 1669 | struct futex_hash_bucket *hb; |
| 1670 | struct futex_q *this, *next; |
| 1671 | u32 uval; |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1672 | struct plist_head *head; |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1673 | union futex_key key = FUTEX_KEY_INIT; |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1674 | int ret; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1675 | |
| 1676 | retry: |
| 1677 | if (get_user(uval, uaddr)) |
| 1678 | return -EFAULT; |
| 1679 | /* |
| 1680 | * We release only a lock we actually own: |
| 1681 | */ |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1682 | if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current)) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1683 | return -EPERM; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1684 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1685 | ret = get_futex_key(uaddr, fshared, &key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1686 | if (unlikely(ret != 0)) |
| 1687 | goto out; |
| 1688 | |
| 1689 | hb = hash_futex(&key); |
| 1690 | spin_lock(&hb->lock); |
| 1691 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1692 | /* |
| 1693 | * To avoid races, try to do the TID -> 0 atomic transition |
| 1694 | * again. If it succeeds then we can return without waking |
| 1695 | * anyone else up: |
| 1696 | */ |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1697 | if (!(uval & FUTEX_OWNER_DIED)) |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1698 | uval = cmpxchg_futex_value_locked(uaddr, task_pid_vnr(current), 0); |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1699 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1700 | |
| 1701 | if (unlikely(uval == -EFAULT)) |
| 1702 | goto pi_faulted; |
| 1703 | /* |
| 1704 | * Rare case: we managed to release the lock atomically, |
| 1705 | * no need to wake anyone else up: |
| 1706 | */ |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1707 | if (unlikely(uval == task_pid_vnr(current))) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1708 | goto out_unlock; |
| 1709 | |
| 1710 | /* |
| 1711 | * Ok, other tasks may need to be woken up - check waiters |
| 1712 | * and do the wakeup if necessary: |
| 1713 | */ |
| 1714 | head = &hb->chain; |
| 1715 | |
Pierre Peiffer | ec92d08 | 2007-05-09 02:35:00 -0700 | [diff] [blame] | 1716 | plist_for_each_entry_safe(this, next, head, list) { |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1717 | if (!match_futex (&this->key, &key)) |
| 1718 | continue; |
| 1719 | ret = wake_futex_pi(uaddr, uval, this); |
| 1720 | /* |
| 1721 | * The atomic access to the futex value |
| 1722 | * generated a pagefault, so retry the |
| 1723 | * user-access and the wakeup: |
| 1724 | */ |
| 1725 | if (ret == -EFAULT) |
| 1726 | goto pi_faulted; |
| 1727 | goto out_unlock; |
| 1728 | } |
| 1729 | /* |
| 1730 | * No waiters - kernel unlocks the futex: |
| 1731 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1732 | if (!(uval & FUTEX_OWNER_DIED)) { |
| 1733 | ret = unlock_futex_pi(uaddr, uval); |
| 1734 | if (ret == -EFAULT) |
| 1735 | goto pi_faulted; |
| 1736 | } |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1737 | |
| 1738 | out_unlock: |
| 1739 | spin_unlock(&hb->lock); |
Peter Zijlstra | 38d47c1 | 2008-09-26 19:32:20 +0200 | [diff] [blame] | 1740 | put_futex_key(fshared, &key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1741 | |
Darren Hart | 42d35d4 | 2008-12-29 15:49:53 -0800 | [diff] [blame] | 1742 | out: |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1743 | return ret; |
| 1744 | |
| 1745 | pi_faulted: |
| 1746 | /* |
Darren Hart | b568636 | 2008-12-18 15:06:34 -0800 | [diff] [blame] | 1747 | * We have to r/w *(int __user *)uaddr, and we have to modify it |
| 1748 | * atomically. Therefore, if we continue to fault after get_user() |
| 1749 | * below, we need to handle the fault ourselves, while still holding |
| 1750 | * the mmap_sem. This can occur if the uaddr is under contention as |
| 1751 | * 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] | 1752 | */ |
Alexey Kuznetsov | 778e9a9 | 2007-06-08 13:47:00 -0700 | [diff] [blame] | 1753 | spin_unlock(&hb->lock); |
Darren Hart | e4dc5b7 | 2009-03-12 00:56:13 -0700 | [diff] [blame] | 1754 | put_futex_key(fshared, &key); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1755 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1756 | ret = get_user(uval, uaddr); |
Darren Hart | b568636 | 2008-12-18 15:06:34 -0800 | [diff] [blame] | 1757 | if (!ret) |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1758 | goto retry; |
| 1759 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1760 | return ret; |
| 1761 | } |
| 1762 | |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1763 | /* |
| 1764 | * Support for robust futexes: the kernel cleans up held futexes at |
| 1765 | * thread exit time. |
| 1766 | * |
| 1767 | * Implementation: user-space maintains a per-thread list of locks it |
| 1768 | * is holding. Upon do_exit(), the kernel carefully walks this list, |
| 1769 | * and marks all locks that are owned by this thread with the |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1770 | * 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] | 1771 | * always manipulated with the lock held, so the list is private and |
| 1772 | * per-thread. Userspace also maintains a per-thread 'list_op_pending' |
| 1773 | * field, to allow the kernel to clean up if the thread dies after |
| 1774 | * acquiring the lock, but just before it could have added itself to |
| 1775 | * the list. There can only be one such pending lock. |
| 1776 | */ |
| 1777 | |
| 1778 | /** |
| 1779 | * sys_set_robust_list - set the robust-futex list head of a task |
| 1780 | * @head: pointer to the list-head |
| 1781 | * @len: length of the list-head, as userspace expects |
| 1782 | */ |
Heiko Carstens | 836f92a | 2009-01-14 14:14:33 +0100 | [diff] [blame] | 1783 | SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head, |
| 1784 | size_t, len) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1785 | { |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 1786 | if (!futex_cmpxchg_enabled) |
| 1787 | return -ENOSYS; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1788 | /* |
| 1789 | * The kernel knows only one size for now: |
| 1790 | */ |
| 1791 | if (unlikely(len != sizeof(*head))) |
| 1792 | return -EINVAL; |
| 1793 | |
| 1794 | current->robust_list = head; |
| 1795 | |
| 1796 | return 0; |
| 1797 | } |
| 1798 | |
| 1799 | /** |
| 1800 | * sys_get_robust_list - get the robust-futex list head of a task |
| 1801 | * @pid: pid of the process [zero for current task] |
| 1802 | * @head_ptr: pointer to a list-head pointer, the kernel fills it in |
| 1803 | * @len_ptr: pointer to a length field, the kernel fills in the header size |
| 1804 | */ |
Heiko Carstens | 836f92a | 2009-01-14 14:14:33 +0100 | [diff] [blame] | 1805 | SYSCALL_DEFINE3(get_robust_list, int, pid, |
| 1806 | struct robust_list_head __user * __user *, head_ptr, |
| 1807 | size_t __user *, len_ptr) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1808 | { |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 1809 | struct robust_list_head __user *head; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1810 | unsigned long ret; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 1811 | const struct cred *cred = current_cred(), *pcred; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1812 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 1813 | if (!futex_cmpxchg_enabled) |
| 1814 | return -ENOSYS; |
| 1815 | |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1816 | if (!pid) |
| 1817 | head = current->robust_list; |
| 1818 | else { |
| 1819 | struct task_struct *p; |
| 1820 | |
| 1821 | ret = -ESRCH; |
Oleg Nesterov | aaa2a97 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 1822 | rcu_read_lock(); |
Pavel Emelyanov | 228ebcb | 2007-10-18 23:40:16 -0700 | [diff] [blame] | 1823 | p = find_task_by_vpid(pid); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1824 | if (!p) |
| 1825 | goto err_unlock; |
| 1826 | ret = -EPERM; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 1827 | pcred = __task_cred(p); |
| 1828 | if (cred->euid != pcred->euid && |
| 1829 | cred->euid != pcred->uid && |
David Howells | 76aac0e | 2008-11-14 10:39:12 +1100 | [diff] [blame] | 1830 | !capable(CAP_SYS_PTRACE)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1831 | goto err_unlock; |
| 1832 | head = p->robust_list; |
Oleg Nesterov | aaa2a97 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 1833 | rcu_read_unlock(); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1834 | } |
| 1835 | |
| 1836 | if (put_user(sizeof(*head), len_ptr)) |
| 1837 | return -EFAULT; |
| 1838 | return put_user(head, head_ptr); |
| 1839 | |
| 1840 | err_unlock: |
Oleg Nesterov | aaa2a97 | 2006-09-29 02:00:55 -0700 | [diff] [blame] | 1841 | rcu_read_unlock(); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1842 | |
| 1843 | return ret; |
| 1844 | } |
| 1845 | |
| 1846 | /* |
| 1847 | * Process a futex-list entry, check whether it's owned by the |
| 1848 | * dying task, and do notification if so: |
| 1849 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1850 | 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] | 1851 | { |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1852 | u32 uval, nval, mval; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1853 | |
Ingo Molnar | 8f17d3a | 2006-03-27 01:16:27 -0800 | [diff] [blame] | 1854 | retry: |
| 1855 | if (get_user(uval, uaddr)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1856 | return -1; |
| 1857 | |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 1858 | if ((uval & FUTEX_TID_MASK) == task_pid_vnr(curr)) { |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1859 | /* |
| 1860 | * Ok, this dying thread is truly holding a futex |
| 1861 | * of interest. Set the OWNER_DIED bit atomically |
| 1862 | * via cmpxchg, and if the value had FUTEX_WAITERS |
| 1863 | * set, wake up a waiter (if any). (We have to do a |
| 1864 | * futex_wake() even if OWNER_DIED is already set - |
| 1865 | * to handle the rare but possible case of recursive |
| 1866 | * thread-death.) The rest of the cleanup is done in |
| 1867 | * userspace. |
| 1868 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1869 | mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; |
| 1870 | nval = futex_atomic_cmpxchg_inatomic(uaddr, uval, mval); |
| 1871 | |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1872 | if (nval == -EFAULT) |
| 1873 | return -1; |
| 1874 | |
| 1875 | if (nval != uval) |
Ingo Molnar | 8f17d3a | 2006-03-27 01:16:27 -0800 | [diff] [blame] | 1876 | goto retry; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1877 | |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1878 | /* |
| 1879 | * Wake robust non-PI futexes here. The wakeup of |
| 1880 | * PI futexes happens in exit_pi_state(): |
| 1881 | */ |
Thomas Gleixner | 36cf3b5 | 2007-07-15 23:41:20 -0700 | [diff] [blame] | 1882 | if (!pi && (uval & FUTEX_WAITERS)) |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1883 | futex_wake(uaddr, 1, 1, FUTEX_BITSET_MATCH_ANY); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1884 | } |
| 1885 | return 0; |
| 1886 | } |
| 1887 | |
| 1888 | /* |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1889 | * Fetch a robust-list pointer. Bit 0 signals PI futexes: |
| 1890 | */ |
| 1891 | static inline int fetch_robust_entry(struct robust_list __user **entry, |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 1892 | struct robust_list __user * __user *head, |
| 1893 | int *pi) |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1894 | { |
| 1895 | unsigned long uentry; |
| 1896 | |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 1897 | if (get_user(uentry, (unsigned long __user *)head)) |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1898 | return -EFAULT; |
| 1899 | |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 1900 | *entry = (void __user *)(uentry & ~1UL); |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1901 | *pi = uentry & 1; |
| 1902 | |
| 1903 | return 0; |
| 1904 | } |
| 1905 | |
| 1906 | /* |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1907 | * Walk curr->robust_list (very carefully, it's a userspace list!) |
| 1908 | * and mark any locks found there dead, and notify any waiters. |
| 1909 | * |
| 1910 | * We silently return on any sign of list-walking problem. |
| 1911 | */ |
| 1912 | void exit_robust_list(struct task_struct *curr) |
| 1913 | { |
| 1914 | struct robust_list_head __user *head = curr->robust_list; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1915 | struct robust_list __user *entry, *next_entry, *pending; |
| 1916 | unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1917 | unsigned long futex_offset; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1918 | int rc; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1919 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 1920 | if (!futex_cmpxchg_enabled) |
| 1921 | return; |
| 1922 | |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1923 | /* |
| 1924 | * Fetch the list head (which was registered earlier, via |
| 1925 | * sys_set_robust_list()): |
| 1926 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1927 | if (fetch_robust_entry(&entry, &head->list.next, &pi)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1928 | return; |
| 1929 | /* |
| 1930 | * Fetch the relative futex offset: |
| 1931 | */ |
| 1932 | if (get_user(futex_offset, &head->futex_offset)) |
| 1933 | return; |
| 1934 | /* |
| 1935 | * Fetch any possibly pending lock-add first, and handle it |
| 1936 | * if it exists: |
| 1937 | */ |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1938 | if (fetch_robust_entry(&pending, &head->list_op_pending, &pip)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1939 | return; |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1940 | |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1941 | next_entry = NULL; /* avoid warning with gcc */ |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1942 | while (entry != &head->list) { |
| 1943 | /* |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1944 | * Fetch the next entry in the list before calling |
| 1945 | * handle_futex_death: |
| 1946 | */ |
| 1947 | rc = fetch_robust_entry(&next_entry, &entry->next, &next_pi); |
| 1948 | /* |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1949 | * A pending lock might already be on the list, so |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 1950 | * don't process it twice: |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1951 | */ |
| 1952 | if (entry != pending) |
Al Viro | ba46df9 | 2006-10-10 22:46:07 +0100 | [diff] [blame] | 1953 | if (handle_futex_death((void __user *)entry + futex_offset, |
Ingo Molnar | e3f2dde | 2006-07-29 05:17:57 +0200 | [diff] [blame] | 1954 | curr, pi)) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1955 | return; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1956 | if (rc) |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1957 | return; |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1958 | entry = next_entry; |
| 1959 | pi = next_pi; |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1960 | /* |
| 1961 | * Avoid excessively long or circular lists: |
| 1962 | */ |
| 1963 | if (!--limit) |
| 1964 | break; |
| 1965 | |
| 1966 | cond_resched(); |
| 1967 | } |
Martin Schwidefsky | 9f96cb1 | 2007-10-01 01:20:13 -0700 | [diff] [blame] | 1968 | |
| 1969 | if (pending) |
| 1970 | handle_futex_death((void __user *)pending + futex_offset, |
| 1971 | curr, pip); |
Ingo Molnar | 0771dfe | 2006-03-27 01:16:22 -0800 | [diff] [blame] | 1972 | } |
| 1973 | |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 1974 | 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] | 1975 | u32 __user *uaddr2, u32 val2, u32 val3) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1976 | { |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1977 | int clockrt, ret = -ENOSYS; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1978 | int cmd = op & FUTEX_CMD_MASK; |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1979 | int fshared = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1980 | |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1981 | if (!(op & FUTEX_PRIVATE_FLAG)) |
Peter Zijlstra | c2f9f20 | 2008-09-26 19:32:23 +0200 | [diff] [blame] | 1982 | fshared = 1; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1983 | |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1984 | clockrt = op & FUTEX_CLOCK_REALTIME; |
| 1985 | if (clockrt && cmd != FUTEX_WAIT_BITSET) |
| 1986 | return -ENOSYS; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 1987 | |
| 1988 | switch (cmd) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1989 | case FUTEX_WAIT: |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1990 | val3 = FUTEX_BITSET_MATCH_ANY; |
| 1991 | case FUTEX_WAIT_BITSET: |
Thomas Gleixner | 1acdac1 | 2008-11-20 10:02:53 -0800 | [diff] [blame] | 1992 | ret = futex_wait(uaddr, fshared, val, timeout, val3, clockrt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1993 | break; |
| 1994 | case FUTEX_WAKE: |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 1995 | val3 = FUTEX_BITSET_MATCH_ANY; |
| 1996 | case FUTEX_WAKE_BITSET: |
| 1997 | ret = futex_wake(uaddr, fshared, val, val3); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1998 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1999 | case FUTEX_REQUEUE: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2000 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2001 | break; |
| 2002 | case FUTEX_CMP_REQUEUE: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2003 | ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2004 | break; |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 2005 | case FUTEX_WAKE_OP: |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2006 | ret = futex_wake_op(uaddr, fshared, uaddr2, val, val2, val3); |
Jakub Jelinek | 4732efb | 2005-09-06 15:16:25 -0700 | [diff] [blame] | 2007 | break; |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2008 | case FUTEX_LOCK_PI: |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2009 | if (futex_cmpxchg_enabled) |
| 2010 | ret = futex_lock_pi(uaddr, fshared, val, timeout, 0); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2011 | break; |
| 2012 | case FUTEX_UNLOCK_PI: |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2013 | if (futex_cmpxchg_enabled) |
| 2014 | ret = futex_unlock_pi(uaddr, fshared); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2015 | break; |
| 2016 | case FUTEX_TRYLOCK_PI: |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2017 | if (futex_cmpxchg_enabled) |
| 2018 | ret = futex_lock_pi(uaddr, fshared, 0, timeout, 1); |
Ingo Molnar | c87e283 | 2006-06-27 02:54:58 -0700 | [diff] [blame] | 2019 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2020 | default: |
| 2021 | ret = -ENOSYS; |
| 2022 | } |
| 2023 | return ret; |
| 2024 | } |
| 2025 | |
| 2026 | |
Heiko Carstens | 17da2bd | 2009-01-14 14:14:10 +0100 | [diff] [blame] | 2027 | SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, |
| 2028 | struct timespec __user *, utime, u32 __user *, uaddr2, |
| 2029 | u32, val3) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2030 | { |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2031 | struct timespec ts; |
| 2032 | ktime_t t, *tp = NULL; |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 2033 | u32 val2 = 0; |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2034 | int cmd = op & FUTEX_CMD_MASK; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2035 | |
Thomas Gleixner | cd68998 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 2036 | if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || |
| 2037 | cmd == FUTEX_WAIT_BITSET)) { |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2038 | if (copy_from_user(&ts, utime, sizeof(ts)) != 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2039 | return -EFAULT; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2040 | if (!timespec_valid(&ts)) |
Thomas Gleixner | 9741ef9 | 2006-03-31 02:31:32 -0800 | [diff] [blame] | 2041 | return -EINVAL; |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2042 | |
| 2043 | t = timespec_to_ktime(ts); |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2044 | if (cmd == FUTEX_WAIT) |
Thomas Gleixner | 5a7780e | 2008-02-13 09:20:43 +0100 | [diff] [blame] | 2045 | t = ktime_add_safe(ktime_get(), t); |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2046 | tp = &t; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2047 | } |
| 2048 | /* |
Eric Dumazet | 34f01cc | 2007-05-09 02:35:04 -0700 | [diff] [blame] | 2049 | * requeue parameter in 'utime' if cmd == FUTEX_REQUEUE. |
Andreas Schwab | f54f098 | 2007-07-31 00:38:51 -0700 | [diff] [blame] | 2050 | * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2051 | */ |
Andreas Schwab | f54f098 | 2007-07-31 00:38:51 -0700 | [diff] [blame] | 2052 | if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || |
| 2053 | cmd == FUTEX_WAKE_OP) |
Ingo Molnar | e2970f2 | 2006-06-27 02:54:47 -0700 | [diff] [blame] | 2054 | val2 = (u32) (unsigned long) utime; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2055 | |
Pierre Peiffer | c19384b | 2007-05-09 02:35:02 -0700 | [diff] [blame] | 2056 | return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2057 | } |
| 2058 | |
Benjamin Herrenschmidt | f6d107f | 2008-03-27 14:52:15 +1100 | [diff] [blame] | 2059 | static int __init futex_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2060 | { |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2061 | u32 curval; |
Thomas Gleixner | 3e4ab74 | 2008-02-23 15:23:55 -0800 | [diff] [blame] | 2062 | int i; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2063 | |
Thomas Gleixner | a0c1e90 | 2008-02-23 15:23:57 -0800 | [diff] [blame] | 2064 | /* |
| 2065 | * This will fail and we want it. Some arch implementations do |
| 2066 | * runtime detection of the futex_atomic_cmpxchg_inatomic() |
| 2067 | * functionality. We want to know that before we call in any |
| 2068 | * of the complex code paths. Also we want to prevent |
| 2069 | * registration of robust lists in that case. NULL is |
| 2070 | * guaranteed to fault and we get -EFAULT on functional |
| 2071 | * implementation, the non functional ones will return |
| 2072 | * -ENOSYS. |
| 2073 | */ |
| 2074 | curval = cmpxchg_futex_value_locked(NULL, 0, 0); |
| 2075 | if (curval == -EFAULT) |
| 2076 | futex_cmpxchg_enabled = 1; |
| 2077 | |
Thomas Gleixner | 3e4ab74 | 2008-02-23 15:23:55 -0800 | [diff] [blame] | 2078 | for (i = 0; i < ARRAY_SIZE(futex_queues); i++) { |
| 2079 | plist_head_init(&futex_queues[i].chain, &futex_queues[i].lock); |
| 2080 | spin_lock_init(&futex_queues[i].lock); |
| 2081 | } |
| 2082 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2083 | return 0; |
| 2084 | } |
Benjamin Herrenschmidt | f6d107f | 2008-03-27 14:52:15 +1100 | [diff] [blame] | 2085 | __initcall(futex_init); |