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202 lines
6.0 KiB
202 lines
6.0 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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* Mutexes: blocking mutual exclusion locks |
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* |
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* started by Ingo Molnar: |
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* |
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* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <[email protected]> |
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* |
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* This file contains the main data structure and API definitions. |
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*/ |
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#ifndef __LINUX_MUTEX_H |
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#define __LINUX_MUTEX_H |
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#include <asm/current.h> |
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#include <linux/list.h> |
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#include <linux/spinlock_types.h> |
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#include <linux/lockdep.h> |
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#include <linux/atomic.h> |
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#include <asm/processor.h> |
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#include <linux/osq_lock.h> |
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#include <linux/debug_locks.h> |
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struct ww_acquire_ctx; |
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/* |
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* Simple, straightforward mutexes with strict semantics: |
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* |
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* - only one task can hold the mutex at a time |
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* - only the owner can unlock the mutex |
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* - multiple unlocks are not permitted |
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* - recursive locking is not permitted |
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* - a mutex object must be initialized via the API |
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* - a mutex object must not be initialized via memset or copying |
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* - task may not exit with mutex held |
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* - memory areas where held locks reside must not be freed |
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* - held mutexes must not be reinitialized |
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* - mutexes may not be used in hardware or software interrupt |
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* contexts such as tasklets and timers |
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* |
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* These semantics are fully enforced when DEBUG_MUTEXES is |
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* enabled. Furthermore, besides enforcing the above rules, the mutex |
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* debugging code also implements a number of additional features |
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* that make lock debugging easier and faster: |
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* |
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* - uses symbolic names of mutexes, whenever they are printed in debug output |
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* - point-of-acquire tracking, symbolic lookup of function names |
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* - list of all locks held in the system, printout of them |
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* - owner tracking |
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* - detects self-recursing locks and prints out all relevant info |
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* - detects multi-task circular deadlocks and prints out all affected |
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* locks and tasks (and only those tasks) |
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*/ |
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struct mutex { |
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atomic_long_t owner; |
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spinlock_t wait_lock; |
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#ifdef CONFIG_MUTEX_SPIN_ON_OWNER |
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struct optimistic_spin_queue osq; /* Spinner MCS lock */ |
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#endif |
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struct list_head wait_list; |
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#ifdef CONFIG_DEBUG_MUTEXES |
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void *magic; |
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#endif |
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#ifdef CONFIG_DEBUG_LOCK_ALLOC |
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struct lockdep_map dep_map; |
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#endif |
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}; |
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struct ww_class; |
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struct ww_acquire_ctx; |
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struct ww_mutex { |
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struct mutex base; |
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struct ww_acquire_ctx *ctx; |
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#ifdef CONFIG_DEBUG_MUTEXES |
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struct ww_class *ww_class; |
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#endif |
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}; |
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/* |
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* This is the control structure for tasks blocked on mutex, |
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* which resides on the blocked task's kernel stack: |
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*/ |
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struct mutex_waiter { |
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struct list_head list; |
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struct task_struct *task; |
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struct ww_acquire_ctx *ww_ctx; |
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#ifdef CONFIG_DEBUG_MUTEXES |
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void *magic; |
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#endif |
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}; |
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#ifdef CONFIG_DEBUG_MUTEXES |
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#define __DEBUG_MUTEX_INITIALIZER(lockname) \ |
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, .magic = &lockname |
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extern void mutex_destroy(struct mutex *lock); |
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#else |
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# define __DEBUG_MUTEX_INITIALIZER(lockname) |
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static inline void mutex_destroy(struct mutex *lock) {} |
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#endif |
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/** |
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* mutex_init - initialize the mutex |
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* @mutex: the mutex to be initialized |
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* |
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* Initialize the mutex to unlocked state. |
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* |
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* It is not allowed to initialize an already locked mutex. |
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*/ |
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#define mutex_init(mutex) \ |
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do { \ |
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static struct lock_class_key __key; \ |
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\ |
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__mutex_init((mutex), #mutex, &__key); \ |
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} while (0) |
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#ifdef CONFIG_DEBUG_LOCK_ALLOC |
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# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ |
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, .dep_map = { \ |
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.name = #lockname, \ |
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.wait_type_inner = LD_WAIT_SLEEP, \ |
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} |
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#else |
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# define __DEP_MAP_MUTEX_INITIALIZER(lockname) |
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#endif |
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#define __MUTEX_INITIALIZER(lockname) \ |
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{ .owner = ATOMIC_LONG_INIT(0) \ |
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, .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ |
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, .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ |
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__DEBUG_MUTEX_INITIALIZER(lockname) \ |
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__DEP_MAP_MUTEX_INITIALIZER(lockname) } |
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#define DEFINE_MUTEX(mutexname) \ |
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struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) |
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extern void __mutex_init(struct mutex *lock, const char *name, |
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struct lock_class_key *key); |
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/** |
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* mutex_is_locked - is the mutex locked |
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* @lock: the mutex to be queried |
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* |
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* Returns true if the mutex is locked, false if unlocked. |
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*/ |
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extern bool mutex_is_locked(struct mutex *lock); |
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/* |
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* See kernel/locking/mutex.c for detailed documentation of these APIs. |
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* Also see Documentation/locking/mutex-design.rst. |
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*/ |
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#ifdef CONFIG_DEBUG_LOCK_ALLOC |
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extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); |
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extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); |
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extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, |
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unsigned int subclass); |
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extern int __must_check mutex_lock_killable_nested(struct mutex *lock, |
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unsigned int subclass); |
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extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass); |
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#define mutex_lock(lock) mutex_lock_nested(lock, 0) |
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#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) |
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#define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) |
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#define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0) |
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#define mutex_lock_nest_lock(lock, nest_lock) \ |
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do { \ |
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typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ |
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_mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ |
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} while (0) |
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#else |
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extern void mutex_lock(struct mutex *lock); |
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extern int __must_check mutex_lock_interruptible(struct mutex *lock); |
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extern int __must_check mutex_lock_killable(struct mutex *lock); |
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extern void mutex_lock_io(struct mutex *lock); |
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# define mutex_lock_nested(lock, subclass) mutex_lock(lock) |
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# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) |
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# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) |
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# define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) |
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# define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock) |
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#endif |
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/* |
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* NOTE: mutex_trylock() follows the spin_trylock() convention, |
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* not the down_trylock() convention! |
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* |
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* Returns 1 if the mutex has been acquired successfully, and 0 on contention. |
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*/ |
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extern int mutex_trylock(struct mutex *lock); |
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extern void mutex_unlock(struct mutex *lock); |
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extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); |
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#endif /* __LINUX_MUTEX_H */
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