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Release 4.12 include/linux/mutex.h

Directory: include/linux
 * Mutexes: blocking mutual exclusion locks
 * started by Ingo Molnar:
 *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <>
 * This file contains the main data structure and API definitions.
#ifndef __LINUX_MUTEX_H

#define __LINUX_MUTEX_H

#include <asm/current.h>
#include <linux/list.h>
#include <linux/spinlock_types.h>
#include <linux/linkage.h>
#include <linux/lockdep.h>
#include <linux/atomic.h>
#include <asm/processor.h>
#include <linux/osq_lock.h>
#include <linux/debug_locks.h>

struct ww_acquire_ctx;

 * Simple, straightforward mutexes with strict semantics:
 * - only one task can hold the mutex at a time
 * - only the owner can unlock the mutex
 * - multiple unlocks are not permitted
 * - recursive locking is not permitted
 * - a mutex object must be initialized via the API
 * - a mutex object must not be initialized via memset or copying
 * - task may not exit with mutex held
 * - memory areas where held locks reside must not be freed
 * - held mutexes must not be reinitialized
 * - mutexes may not be used in hardware or software interrupt
 *   contexts such as tasklets and timers
 * These semantics are fully enforced when DEBUG_MUTEXES is
 * enabled. Furthermore, besides enforcing the above rules, the mutex
 * debugging code also implements a number of additional features
 * that make lock debugging easier and faster:
 * - uses symbolic names of mutexes, whenever they are printed in debug output
 * - point-of-acquire tracking, symbolic lookup of function names
 * - list of all locks held in the system, printout of them
 * - owner tracking
 * - detects self-recursing locks and prints out all relevant info
 * - detects multi-task circular deadlocks and prints out all affected
 *   locks and tasks (and only those tasks)

struct mutex {
atomic_long_t		owner;
spinlock_t		wait_lock;
struct optimistic_spin_queue osq; /* Spinner MCS lock */
struct list_head	wait_list;
void			*magic;
struct lockdep_map	dep_map;

static inline struct task_struct *__mutex_owner(struct mutex *lock) { return (struct task_struct *)(atomic_long_read(&lock->owner) & ~0x07); }


Peter Zijlstra33100.00%2100.00%

/* * This is the control structure for tasks blocked on mutex, * which resides on the blocked task's kernel stack: */ struct mutex_waiter { struct list_head list; struct task_struct *task; struct ww_acquire_ctx *ww_ctx; #ifdef CONFIG_DEBUG_MUTEXES void *magic; #endif }; #ifdef CONFIG_DEBUG_MUTEXES #define __DEBUG_MUTEX_INITIALIZER(lockname) \ , .magic = &lockname extern void mutex_destroy(struct mutex *lock); #else # define __DEBUG_MUTEX_INITIALIZER(lockname)
static inline void mutex_destroy(struct mutex *lock) {}


Jean Delvare763.64%150.00%
Ingo Molnar436.36%150.00%

#endif /** * mutex_init - initialize the mutex * @mutex: the mutex to be initialized * * Initialize the mutex to unlocked state. * * It is not allowed to initialize an already locked mutex. */ #define mutex_init(mutex) \ do { \ static struct lock_class_key __key; \ \ __mutex_init((mutex), #mutex, &__key); \ } while (0) #ifdef CONFIG_DEBUG_LOCK_ALLOC # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ , .dep_map = { .name = #lockname } #else # define __DEP_MAP_MUTEX_INITIALIZER(lockname) #endif #define __MUTEX_INITIALIZER(lockname) \ { .owner = ATOMIC_LONG_INIT(0) \ , .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ __DEBUG_MUTEX_INITIALIZER(lockname) \ __DEP_MAP_MUTEX_INITIALIZER(lockname) } #define DEFINE_MUTEX(mutexname) \ struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) extern void __mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key); /** * mutex_is_locked - is the mutex locked * @lock: the mutex to be queried * * Returns 1 if the mutex is locked, 0 if unlocked. */
static inline int mutex_is_locked(struct mutex *lock) { /* * XXX think about spin_is_locked */ return __mutex_owner(lock) != NULL; }


Ingo Molnar1885.71%150.00%
Peter Zijlstra314.29%150.00%

/* * See kernel/locking/mutex.c for detailed documentation of these APIs. * Also see Documentation/locking/mutex-design.txt. */ #ifdef CONFIG_DEBUG_LOCK_ALLOC extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass); extern int __must_check mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass); extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass); #define mutex_lock(lock) mutex_lock_nested(lock, 0) #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) #define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0) #define mutex_lock_nest_lock(lock, nest_lock) \ do { \ typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ } while (0) #else extern void mutex_lock(struct mutex *lock); extern int __must_check mutex_lock_interruptible(struct mutex *lock); extern int __must_check mutex_lock_killable(struct mutex *lock); extern void mutex_lock_io(struct mutex *lock); # define mutex_lock_nested(lock, subclass) mutex_lock(lock) # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) # define mutex_lock_io_nested(lock, subclass) mutex_lock(lock) #endif /* * NOTE: mutex_trylock() follows the spin_trylock() convention, * not the down_trylock() convention! * * Returns 1 if the mutex has been acquired successfully, and 0 on contention. */ extern int mutex_trylock(struct mutex *lock); extern void mutex_unlock(struct mutex *lock); extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); /* * These values are chosen such that FAIL and SUCCESS match the * values of the regular mutex_trylock(). */ enum mutex_trylock_recursive_enum { MUTEX_TRYLOCK_FAILED = 0, MUTEX_TRYLOCK_SUCCESS = 1, MUTEX_TRYLOCK_RECURSIVE, }; /** * mutex_trylock_recursive - trylock variant that allows recursive locking * @lock: mutex to be locked * * This function should not be used, _ever_. It is purely for hysterical GEM * raisins, and once those are gone this will be removed. * * Returns: * MUTEX_TRYLOCK_FAILED - trylock failed, * MUTEX_TRYLOCK_SUCCESS - lock acquired, * MUTEX_TRYLOCK_RECURSIVE - we already owned the lock. */
static inline /* __deprecated */ __must_check enum mutex_trylock_recursive_enum mutex_trylock_recursive(struct mutex *lock) { if (unlikely(__mutex_owner(lock) == current)) return MUTEX_TRYLOCK_RECURSIVE; return mutex_trylock(lock); }


Peter Zijlstra3494.44%150.00%
Ingo Molnar25.56%150.00%

#endif /* __LINUX_MUTEX_H */

Overall Contributors

Ingo Molnar22439.37%413.33%
Peter Zijlstra18933.22%723.33%
Liam R. Howlett427.38%13.33%
Tejun Heo376.50%13.33%
Neil Brown183.16%13.33%
Eric Paris122.11%13.33%
Nicolai Hähnle81.41%13.33%
Jean Delvare71.23%13.33%
Waiman Long71.23%13.33%
Maarten Lankhorst40.70%13.33%
Andrew Morton40.70%26.67%
Jason Low40.70%13.33%
David S. Miller30.53%13.33%
Heiko Carstens30.53%13.33%
Tim Chen20.35%13.33%
Robert P. J. Day10.18%13.33%
Arjan van de Ven10.18%13.33%
Matti Linnanvuori10.18%13.33%
Arun Sharma10.18%13.33%
Davidlohr Bueso A10.18%13.33%
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