Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 1 | /* |
| 2 | * kernel/mutex.c |
| 3 | * |
| 4 | * Mutexes: blocking mutual exclusion locks |
| 5 | * |
| 6 | * Started by Ingo Molnar: |
| 7 | * |
| 8 | * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
| 9 | * |
| 10 | * Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and |
| 11 | * David Howells for suggestions and improvements. |
| 12 | * |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 13 | * - Adaptive spinning for mutexes by Peter Zijlstra. (Ported to mainline |
| 14 | * from the -rt tree, where it was originally implemented for rtmutexes |
| 15 | * by Steven Rostedt, based on work by Gregory Haskins, Peter Morreale |
| 16 | * and Sven Dietrich. |
| 17 | * |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 18 | * Also see Documentation/mutex-design.txt. |
| 19 | */ |
| 20 | #include <linux/mutex.h> |
| 21 | #include <linux/sched.h> |
| 22 | #include <linux/module.h> |
| 23 | #include <linux/spinlock.h> |
| 24 | #include <linux/interrupt.h> |
Ingo Molnar | 9a11b49a | 2006-07-03 00:24:33 -0700 | [diff] [blame] | 25 | #include <linux/debug_locks.h> |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 26 | |
| 27 | /* |
| 28 | * In the DEBUG case we are using the "NULL fastpath" for mutexes, |
| 29 | * which forces all calls into the slowpath: |
| 30 | */ |
| 31 | #ifdef CONFIG_DEBUG_MUTEXES |
| 32 | # include "mutex-debug.h" |
| 33 | # include <asm-generic/mutex-null.h> |
| 34 | #else |
| 35 | # include "mutex.h" |
| 36 | # include <asm/mutex.h> |
| 37 | #endif |
| 38 | |
| 39 | /*** |
| 40 | * mutex_init - initialize the mutex |
| 41 | * @lock: the mutex to be initialized |
Randy Dunlap | 0e241ff | 2008-07-24 16:58:42 -0700 | [diff] [blame] | 42 | * @key: the lock_class_key for the class; used by mutex lock debugging |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 43 | * |
| 44 | * Initialize the mutex to unlocked state. |
| 45 | * |
| 46 | * It is not allowed to initialize an already locked mutex. |
| 47 | */ |
Ingo Molnar | ef5d470 | 2006-07-03 00:24:55 -0700 | [diff] [blame] | 48 | void |
| 49 | __mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key) |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 50 | { |
| 51 | atomic_set(&lock->count, 1); |
| 52 | spin_lock_init(&lock->wait_lock); |
| 53 | INIT_LIST_HEAD(&lock->wait_list); |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 54 | mutex_clear_owner(lock); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 55 | |
Ingo Molnar | ef5d470 | 2006-07-03 00:24:55 -0700 | [diff] [blame] | 56 | debug_mutex_init(lock, name, key); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 57 | } |
| 58 | |
| 59 | EXPORT_SYMBOL(__mutex_init); |
| 60 | |
Peter Zijlstra | e4564f7 | 2007-10-11 22:11:12 +0200 | [diff] [blame] | 61 | #ifndef CONFIG_DEBUG_LOCK_ALLOC |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 62 | /* |
| 63 | * We split the mutex lock/unlock logic into separate fastpath and |
| 64 | * slowpath functions, to reduce the register pressure on the fastpath. |
| 65 | * We also put the fastpath first in the kernel image, to make sure the |
| 66 | * branch is predicted by the CPU as default-untaken. |
| 67 | */ |
Török Edwin | 7918baa | 2008-11-24 10:17:42 +0200 | [diff] [blame] | 68 | static __used noinline void __sched |
Ingo Molnar | 9a11b49a | 2006-07-03 00:24:33 -0700 | [diff] [blame] | 69 | __mutex_lock_slowpath(atomic_t *lock_count); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 70 | |
| 71 | /*** |
| 72 | * mutex_lock - acquire the mutex |
| 73 | * @lock: the mutex to be acquired |
| 74 | * |
| 75 | * Lock the mutex exclusively for this task. If the mutex is not |
| 76 | * available right now, it will sleep until it can get it. |
| 77 | * |
| 78 | * The mutex must later on be released by the same task that |
| 79 | * acquired it. Recursive locking is not allowed. The task |
| 80 | * may not exit without first unlocking the mutex. Also, kernel |
| 81 | * memory where the mutex resides mutex must not be freed with |
| 82 | * the mutex still locked. The mutex must first be initialized |
| 83 | * (or statically defined) before it can be locked. memset()-ing |
| 84 | * the mutex to 0 is not allowed. |
| 85 | * |
| 86 | * ( The CONFIG_DEBUG_MUTEXES .config option turns on debugging |
| 87 | * checks that will enforce the restrictions and will also do |
| 88 | * deadlock debugging. ) |
| 89 | * |
| 90 | * This function is similar to (but not equivalent to) down(). |
| 91 | */ |
Harvey Harrison | 7ad5b3a | 2008-02-08 04:19:53 -0800 | [diff] [blame] | 92 | void inline __sched mutex_lock(struct mutex *lock) |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 93 | { |
Ingo Molnar | c544bdb | 2006-01-10 22:10:36 +0100 | [diff] [blame] | 94 | might_sleep(); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 95 | /* |
| 96 | * The locking fastpath is the 1->0 transition from |
| 97 | * 'unlocked' into 'locked' state. |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 98 | */ |
| 99 | __mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath); |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 100 | mutex_set_owner(lock); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 101 | } |
| 102 | |
| 103 | EXPORT_SYMBOL(mutex_lock); |
Peter Zijlstra | e4564f7 | 2007-10-11 22:11:12 +0200 | [diff] [blame] | 104 | #endif |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 105 | |
Török Edwin | 7918baa | 2008-11-24 10:17:42 +0200 | [diff] [blame] | 106 | static __used noinline void __sched __mutex_unlock_slowpath(atomic_t *lock_count); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 107 | |
| 108 | /*** |
| 109 | * mutex_unlock - release the mutex |
| 110 | * @lock: the mutex to be released |
| 111 | * |
| 112 | * Unlock a mutex that has been locked by this task previously. |
| 113 | * |
| 114 | * This function must not be used in interrupt context. Unlocking |
| 115 | * of a not locked mutex is not allowed. |
| 116 | * |
| 117 | * This function is similar to (but not equivalent to) up(). |
| 118 | */ |
Harvey Harrison | 7ad5b3a | 2008-02-08 04:19:53 -0800 | [diff] [blame] | 119 | void __sched mutex_unlock(struct mutex *lock) |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 120 | { |
| 121 | /* |
| 122 | * The unlocking fastpath is the 0->1 transition from 'locked' |
| 123 | * into 'unlocked' state: |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 124 | */ |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 125 | #ifndef CONFIG_DEBUG_MUTEXES |
| 126 | /* |
| 127 | * When debugging is enabled we must not clear the owner before time, |
| 128 | * the slow path will always be taken, and that clears the owner field |
| 129 | * after verifying that it was indeed current. |
| 130 | */ |
| 131 | mutex_clear_owner(lock); |
| 132 | #endif |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 133 | __mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath); |
| 134 | } |
| 135 | |
| 136 | EXPORT_SYMBOL(mutex_unlock); |
| 137 | |
| 138 | /* |
| 139 | * Lock a mutex (possibly interruptible), slowpath: |
| 140 | */ |
| 141 | static inline int __sched |
Peter Zijlstra | e4564f7 | 2007-10-11 22:11:12 +0200 | [diff] [blame] | 142 | __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, |
| 143 | unsigned long ip) |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 144 | { |
| 145 | struct task_struct *task = current; |
| 146 | struct mutex_waiter waiter; |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 147 | unsigned long flags; |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 148 | |
Peter Zijlstra | 41719b0 | 2009-01-14 15:36:26 +0100 | [diff] [blame] | 149 | preempt_disable(); |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 150 | mutex_acquire(&lock->dep_map, subclass, 0, ip); |
Heiko Carstens | 36cd3c9 | 2009-04-09 18:48:34 +0200 | [diff] [blame] | 151 | #if defined(CONFIG_SMP) && !defined(CONFIG_DEBUG_MUTEXES) && \ |
| 152 | !defined(CONFIG_HAVE_DEFAULT_NO_SPIN_MUTEXES) |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 153 | /* |
| 154 | * Optimistic spinning. |
| 155 | * |
| 156 | * We try to spin for acquisition when we find that there are no |
| 157 | * pending waiters and the lock owner is currently running on a |
| 158 | * (different) CPU. |
| 159 | * |
| 160 | * The rationale is that if the lock owner is running, it is likely to |
| 161 | * release the lock soon. |
| 162 | * |
| 163 | * Since this needs the lock owner, and this mutex implementation |
| 164 | * doesn't track the owner atomically in the lock field, we need to |
| 165 | * track it non-atomically. |
| 166 | * |
| 167 | * We can't do this for DEBUG_MUTEXES because that relies on wait_lock |
| 168 | * to serialize everything. |
| 169 | */ |
| 170 | |
| 171 | for (;;) { |
| 172 | struct thread_info *owner; |
| 173 | |
| 174 | /* |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 175 | * If there's an owner, wait for it to either |
| 176 | * release the lock or go to sleep. |
| 177 | */ |
| 178 | owner = ACCESS_ONCE(lock->owner); |
| 179 | if (owner && !mutex_spin_on_owner(lock, owner)) |
| 180 | break; |
| 181 | |
Chris Mason | ac6e60e | 2009-01-14 17:29:31 +0100 | [diff] [blame] | 182 | if (atomic_cmpxchg(&lock->count, 1, 0) == 1) { |
| 183 | lock_acquired(&lock->dep_map, ip); |
| 184 | mutex_set_owner(lock); |
| 185 | preempt_enable(); |
| 186 | return 0; |
| 187 | } |
| 188 | |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 189 | /* |
| 190 | * When there's no owner, we might have preempted between the |
| 191 | * owner acquiring the lock and setting the owner field. If |
| 192 | * we're an RT task that will live-lock because we won't let |
| 193 | * the owner complete. |
| 194 | */ |
| 195 | if (!owner && (need_resched() || rt_task(task))) |
| 196 | break; |
| 197 | |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 198 | /* |
| 199 | * The cpu_relax() call is a compiler barrier which forces |
| 200 | * everything in this loop to be re-loaded. We don't need |
| 201 | * memory barriers as we'll eventually observe the right |
| 202 | * values at the cost of a few extra spins. |
| 203 | */ |
| 204 | cpu_relax(); |
| 205 | } |
| 206 | #endif |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 207 | spin_lock_mutex(&lock->wait_lock, flags); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 208 | |
Ingo Molnar | 9a11b49a | 2006-07-03 00:24:33 -0700 | [diff] [blame] | 209 | debug_mutex_lock_common(lock, &waiter); |
Roman Zippel | c9f4f06 | 2007-05-09 02:35:16 -0700 | [diff] [blame] | 210 | debug_mutex_add_waiter(lock, &waiter, task_thread_info(task)); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 211 | |
| 212 | /* add waiting tasks to the end of the waitqueue (FIFO): */ |
| 213 | list_add_tail(&waiter.list, &lock->wait_list); |
| 214 | waiter.task = task; |
| 215 | |
Peter Zijlstra | 93d81d1 | 2009-01-14 15:32:51 +0100 | [diff] [blame] | 216 | if (atomic_xchg(&lock->count, -1) == 1) |
Peter Zijlstra | 4fe8774 | 2007-07-19 01:48:58 -0700 | [diff] [blame] | 217 | goto done; |
| 218 | |
Peter Zijlstra | e4564f7 | 2007-10-11 22:11:12 +0200 | [diff] [blame] | 219 | lock_contended(&lock->dep_map, ip); |
Peter Zijlstra | 4fe8774 | 2007-07-19 01:48:58 -0700 | [diff] [blame] | 220 | |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 221 | for (;;) { |
| 222 | /* |
| 223 | * Lets try to take the lock again - this is needed even if |
| 224 | * we get here for the first time (shortly after failing to |
| 225 | * acquire the lock), to make sure that we get a wakeup once |
| 226 | * it's unlocked. Later on, if we sleep, this is the |
| 227 | * operation that gives us the lock. We xchg it to -1, so |
| 228 | * that when we release the lock, we properly wake up the |
| 229 | * other waiters: |
| 230 | */ |
Peter Zijlstra | 93d81d1 | 2009-01-14 15:32:51 +0100 | [diff] [blame] | 231 | if (atomic_xchg(&lock->count, -1) == 1) |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 232 | break; |
| 233 | |
| 234 | /* |
| 235 | * got a signal? (This code gets eliminated in the |
| 236 | * TASK_UNINTERRUPTIBLE case.) |
| 237 | */ |
Oleg Nesterov | 6ad3676 | 2008-06-08 21:20:42 +0400 | [diff] [blame] | 238 | if (unlikely(signal_pending_state(state, task))) { |
Liam R. Howlett | ad77653 | 2007-12-06 17:37:59 -0500 | [diff] [blame] | 239 | mutex_remove_waiter(lock, &waiter, |
| 240 | task_thread_info(task)); |
Peter Zijlstra | e4564f7 | 2007-10-11 22:11:12 +0200 | [diff] [blame] | 241 | mutex_release(&lock->dep_map, 1, ip); |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 242 | spin_unlock_mutex(&lock->wait_lock, flags); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 243 | |
| 244 | debug_mutex_free_waiter(&waiter); |
Peter Zijlstra | 41719b0 | 2009-01-14 15:36:26 +0100 | [diff] [blame] | 245 | preempt_enable(); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 246 | return -EINTR; |
| 247 | } |
| 248 | __set_task_state(task, state); |
| 249 | |
| 250 | /* didnt get the lock, go to sleep: */ |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 251 | spin_unlock_mutex(&lock->wait_lock, flags); |
Peter Zijlstra | 41719b0 | 2009-01-14 15:36:26 +0100 | [diff] [blame] | 252 | __schedule(); |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 253 | spin_lock_mutex(&lock->wait_lock, flags); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 254 | } |
| 255 | |
Peter Zijlstra | 4fe8774 | 2007-07-19 01:48:58 -0700 | [diff] [blame] | 256 | done: |
Peter Zijlstra | c7e78cf | 2008-10-16 23:17:09 +0200 | [diff] [blame] | 257 | lock_acquired(&lock->dep_map, ip); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 258 | /* got the lock - rejoice! */ |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 259 | mutex_remove_waiter(lock, &waiter, current_thread_info()); |
| 260 | mutex_set_owner(lock); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 261 | |
| 262 | /* set it to 0 if there are no waiters left: */ |
| 263 | if (likely(list_empty(&lock->wait_list))) |
| 264 | atomic_set(&lock->count, 0); |
| 265 | |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 266 | spin_unlock_mutex(&lock->wait_lock, flags); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 267 | |
| 268 | debug_mutex_free_waiter(&waiter); |
Peter Zijlstra | 41719b0 | 2009-01-14 15:36:26 +0100 | [diff] [blame] | 269 | preempt_enable(); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 270 | |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 271 | return 0; |
| 272 | } |
| 273 | |
Ingo Molnar | ef5d470 | 2006-07-03 00:24:55 -0700 | [diff] [blame] | 274 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| 275 | void __sched |
| 276 | mutex_lock_nested(struct mutex *lock, unsigned int subclass) |
| 277 | { |
| 278 | might_sleep(); |
Peter Zijlstra | e4564f7 | 2007-10-11 22:11:12 +0200 | [diff] [blame] | 279 | __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, _RET_IP_); |
Ingo Molnar | ef5d470 | 2006-07-03 00:24:55 -0700 | [diff] [blame] | 280 | } |
| 281 | |
| 282 | EXPORT_SYMBOL_GPL(mutex_lock_nested); |
NeilBrown | d63a5a7 | 2006-12-08 02:36:17 -0800 | [diff] [blame] | 283 | |
| 284 | int __sched |
Liam R. Howlett | ad77653 | 2007-12-06 17:37:59 -0500 | [diff] [blame] | 285 | mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass) |
| 286 | { |
| 287 | might_sleep(); |
| 288 | return __mutex_lock_common(lock, TASK_KILLABLE, subclass, _RET_IP_); |
| 289 | } |
| 290 | EXPORT_SYMBOL_GPL(mutex_lock_killable_nested); |
| 291 | |
| 292 | int __sched |
NeilBrown | d63a5a7 | 2006-12-08 02:36:17 -0800 | [diff] [blame] | 293 | mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass) |
| 294 | { |
| 295 | might_sleep(); |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 296 | return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, |
| 297 | subclass, _RET_IP_); |
NeilBrown | d63a5a7 | 2006-12-08 02:36:17 -0800 | [diff] [blame] | 298 | } |
| 299 | |
| 300 | EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested); |
Ingo Molnar | ef5d470 | 2006-07-03 00:24:55 -0700 | [diff] [blame] | 301 | #endif |
| 302 | |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 303 | /* |
| 304 | * Release the lock, slowpath: |
| 305 | */ |
Harvey Harrison | 7ad5b3a | 2008-02-08 04:19:53 -0800 | [diff] [blame] | 306 | static inline void |
Ingo Molnar | ef5d470 | 2006-07-03 00:24:55 -0700 | [diff] [blame] | 307 | __mutex_unlock_common_slowpath(atomic_t *lock_count, int nested) |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 308 | { |
Ingo Molnar | 0270664 | 2006-01-10 23:15:02 +0100 | [diff] [blame] | 309 | struct mutex *lock = container_of(lock_count, struct mutex, count); |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 310 | unsigned long flags; |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 311 | |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 312 | spin_lock_mutex(&lock->wait_lock, flags); |
Ingo Molnar | ef5d470 | 2006-07-03 00:24:55 -0700 | [diff] [blame] | 313 | mutex_release(&lock->dep_map, nested, _RET_IP_); |
Ingo Molnar | 9a11b49a | 2006-07-03 00:24:33 -0700 | [diff] [blame] | 314 | debug_mutex_unlock(lock); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 315 | |
| 316 | /* |
| 317 | * some architectures leave the lock unlocked in the fastpath failure |
| 318 | * case, others need to leave it locked. In the later case we have to |
| 319 | * unlock it here |
| 320 | */ |
| 321 | if (__mutex_slowpath_needs_to_unlock()) |
| 322 | atomic_set(&lock->count, 1); |
| 323 | |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 324 | if (!list_empty(&lock->wait_list)) { |
| 325 | /* get the first entry from the wait-list: */ |
| 326 | struct mutex_waiter *waiter = |
| 327 | list_entry(lock->wait_list.next, |
| 328 | struct mutex_waiter, list); |
| 329 | |
| 330 | debug_mutex_wake_waiter(lock, waiter); |
| 331 | |
| 332 | wake_up_process(waiter->task); |
| 333 | } |
| 334 | |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 335 | spin_unlock_mutex(&lock->wait_lock, flags); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 336 | } |
| 337 | |
| 338 | /* |
Ingo Molnar | 9a11b49a | 2006-07-03 00:24:33 -0700 | [diff] [blame] | 339 | * Release the lock, slowpath: |
| 340 | */ |
Török Edwin | 7918baa | 2008-11-24 10:17:42 +0200 | [diff] [blame] | 341 | static __used noinline void |
Ingo Molnar | 9a11b49a | 2006-07-03 00:24:33 -0700 | [diff] [blame] | 342 | __mutex_unlock_slowpath(atomic_t *lock_count) |
| 343 | { |
Ingo Molnar | ef5d470 | 2006-07-03 00:24:55 -0700 | [diff] [blame] | 344 | __mutex_unlock_common_slowpath(lock_count, 1); |
Ingo Molnar | 9a11b49a | 2006-07-03 00:24:33 -0700 | [diff] [blame] | 345 | } |
| 346 | |
Peter Zijlstra | e4564f7 | 2007-10-11 22:11:12 +0200 | [diff] [blame] | 347 | #ifndef CONFIG_DEBUG_LOCK_ALLOC |
Ingo Molnar | 9a11b49a | 2006-07-03 00:24:33 -0700 | [diff] [blame] | 348 | /* |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 349 | * Here come the less common (and hence less performance-critical) APIs: |
| 350 | * mutex_lock_interruptible() and mutex_trylock(). |
| 351 | */ |
Harvey Harrison | 7ad5b3a | 2008-02-08 04:19:53 -0800 | [diff] [blame] | 352 | static noinline int __sched |
Liam R. Howlett | ad77653 | 2007-12-06 17:37:59 -0500 | [diff] [blame] | 353 | __mutex_lock_killable_slowpath(atomic_t *lock_count); |
| 354 | |
Harvey Harrison | 7ad5b3a | 2008-02-08 04:19:53 -0800 | [diff] [blame] | 355 | static noinline int __sched |
Ingo Molnar | 9a11b49a | 2006-07-03 00:24:33 -0700 | [diff] [blame] | 356 | __mutex_lock_interruptible_slowpath(atomic_t *lock_count); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 357 | |
| 358 | /*** |
| 359 | * mutex_lock_interruptible - acquire the mutex, interruptable |
| 360 | * @lock: the mutex to be acquired |
| 361 | * |
| 362 | * Lock the mutex like mutex_lock(), and return 0 if the mutex has |
| 363 | * been acquired or sleep until the mutex becomes available. If a |
| 364 | * signal arrives while waiting for the lock then this function |
| 365 | * returns -EINTR. |
| 366 | * |
| 367 | * This function is similar to (but not equivalent to) down_interruptible(). |
| 368 | */ |
Harvey Harrison | 7ad5b3a | 2008-02-08 04:19:53 -0800 | [diff] [blame] | 369 | int __sched mutex_lock_interruptible(struct mutex *lock) |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 370 | { |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 371 | int ret; |
| 372 | |
Ingo Molnar | c544bdb | 2006-01-10 22:10:36 +0100 | [diff] [blame] | 373 | might_sleep(); |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 374 | ret = __mutex_fastpath_lock_retval |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 375 | (&lock->count, __mutex_lock_interruptible_slowpath); |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 376 | if (!ret) |
| 377 | mutex_set_owner(lock); |
| 378 | |
| 379 | return ret; |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 380 | } |
| 381 | |
| 382 | EXPORT_SYMBOL(mutex_lock_interruptible); |
| 383 | |
Harvey Harrison | 7ad5b3a | 2008-02-08 04:19:53 -0800 | [diff] [blame] | 384 | int __sched mutex_lock_killable(struct mutex *lock) |
Liam R. Howlett | ad77653 | 2007-12-06 17:37:59 -0500 | [diff] [blame] | 385 | { |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 386 | int ret; |
| 387 | |
Liam R. Howlett | ad77653 | 2007-12-06 17:37:59 -0500 | [diff] [blame] | 388 | might_sleep(); |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 389 | ret = __mutex_fastpath_lock_retval |
Liam R. Howlett | ad77653 | 2007-12-06 17:37:59 -0500 | [diff] [blame] | 390 | (&lock->count, __mutex_lock_killable_slowpath); |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 391 | if (!ret) |
| 392 | mutex_set_owner(lock); |
| 393 | |
| 394 | return ret; |
Liam R. Howlett | ad77653 | 2007-12-06 17:37:59 -0500 | [diff] [blame] | 395 | } |
| 396 | EXPORT_SYMBOL(mutex_lock_killable); |
| 397 | |
Török Edwin | 7918baa | 2008-11-24 10:17:42 +0200 | [diff] [blame] | 398 | static __used noinline void __sched |
Peter Zijlstra | e4564f7 | 2007-10-11 22:11:12 +0200 | [diff] [blame] | 399 | __mutex_lock_slowpath(atomic_t *lock_count) |
| 400 | { |
| 401 | struct mutex *lock = container_of(lock_count, struct mutex, count); |
| 402 | |
| 403 | __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, _RET_IP_); |
| 404 | } |
| 405 | |
Harvey Harrison | 7ad5b3a | 2008-02-08 04:19:53 -0800 | [diff] [blame] | 406 | static noinline int __sched |
Liam R. Howlett | ad77653 | 2007-12-06 17:37:59 -0500 | [diff] [blame] | 407 | __mutex_lock_killable_slowpath(atomic_t *lock_count) |
| 408 | { |
| 409 | struct mutex *lock = container_of(lock_count, struct mutex, count); |
| 410 | |
| 411 | return __mutex_lock_common(lock, TASK_KILLABLE, 0, _RET_IP_); |
| 412 | } |
| 413 | |
Harvey Harrison | 7ad5b3a | 2008-02-08 04:19:53 -0800 | [diff] [blame] | 414 | static noinline int __sched |
Ingo Molnar | 9a11b49a | 2006-07-03 00:24:33 -0700 | [diff] [blame] | 415 | __mutex_lock_interruptible_slowpath(atomic_t *lock_count) |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 416 | { |
| 417 | struct mutex *lock = container_of(lock_count, struct mutex, count); |
| 418 | |
Peter Zijlstra | e4564f7 | 2007-10-11 22:11:12 +0200 | [diff] [blame] | 419 | return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, _RET_IP_); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 420 | } |
Peter Zijlstra | e4564f7 | 2007-10-11 22:11:12 +0200 | [diff] [blame] | 421 | #endif |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 422 | |
| 423 | /* |
| 424 | * Spinlock based trylock, we take the spinlock and check whether we |
| 425 | * can get the lock: |
| 426 | */ |
| 427 | static inline int __mutex_trylock_slowpath(atomic_t *lock_count) |
| 428 | { |
| 429 | struct mutex *lock = container_of(lock_count, struct mutex, count); |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 430 | unsigned long flags; |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 431 | int prev; |
| 432 | |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 433 | spin_lock_mutex(&lock->wait_lock, flags); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 434 | |
| 435 | prev = atomic_xchg(&lock->count, -1); |
Ingo Molnar | ef5d470 | 2006-07-03 00:24:55 -0700 | [diff] [blame] | 436 | if (likely(prev == 1)) { |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 437 | mutex_set_owner(lock); |
Ingo Molnar | ef5d470 | 2006-07-03 00:24:55 -0700 | [diff] [blame] | 438 | mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_); |
| 439 | } |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 440 | |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 441 | /* Set it back to 0 if there are no waiters: */ |
| 442 | if (likely(list_empty(&lock->wait_list))) |
| 443 | atomic_set(&lock->count, 0); |
| 444 | |
Ingo Molnar | 1fb00c6 | 2006-06-26 00:24:31 -0700 | [diff] [blame] | 445 | spin_unlock_mutex(&lock->wait_lock, flags); |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 446 | |
| 447 | return prev == 1; |
| 448 | } |
| 449 | |
| 450 | /*** |
| 451 | * mutex_trylock - try acquire the mutex, without waiting |
| 452 | * @lock: the mutex to be acquired |
| 453 | * |
| 454 | * Try to acquire the mutex atomically. Returns 1 if the mutex |
| 455 | * has been acquired successfully, and 0 on contention. |
| 456 | * |
| 457 | * NOTE: this function follows the spin_trylock() convention, so |
| 458 | * it is negated to the down_trylock() return values! Be careful |
| 459 | * about this when converting semaphore users to mutexes. |
| 460 | * |
| 461 | * This function must not be used in interrupt context. The |
| 462 | * mutex must be released by the same task that acquired it. |
| 463 | */ |
Harvey Harrison | 7ad5b3a | 2008-02-08 04:19:53 -0800 | [diff] [blame] | 464 | int __sched mutex_trylock(struct mutex *lock) |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 465 | { |
Peter Zijlstra | 0d66bf6 | 2009-01-12 14:01:47 +0100 | [diff] [blame] | 466 | int ret; |
| 467 | |
| 468 | ret = __mutex_fastpath_trylock(&lock->count, __mutex_trylock_slowpath); |
| 469 | if (ret) |
| 470 | mutex_set_owner(lock); |
| 471 | |
| 472 | return ret; |
Ingo Molnar | 6053ee3 | 2006-01-09 15:59:19 -0800 | [diff] [blame] | 473 | } |
| 474 | |
| 475 | EXPORT_SYMBOL(mutex_trylock); |