232 lines
6.9 KiB
C
232 lines
6.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* Mutexes: blocking mutual exclusion locks
|
|
*
|
|
* started by Ingo Molnar:
|
|
*
|
|
* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
|
|
*
|
|
* 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;
|
|
#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
|
|
struct optimistic_spin_queue osq; /* Spinner MCS lock */
|
|
#endif
|
|
struct list_head wait_list;
|
|
#ifdef CONFIG_DEBUG_MUTEXES
|
|
void *magic;
|
|
#endif
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
struct lockdep_map dep_map;
|
|
#endif
|
|
};
|
|
|
|
static inline struct task_struct *__mutex_owner(struct mutex *lock)
|
|
{
|
|
return (struct task_struct *)(atomic_long_read(&lock->owner) & ~0x07);
|
|
}
|
|
|
|
/*
|
|
* 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) {}
|
|
|
|
#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 true if the mutex is locked, false if unlocked.
|
|
*/
|
|
static inline bool mutex_is_locked(struct mutex *lock)
|
|
{
|
|
/*
|
|
* XXX think about spin_is_locked
|
|
*/
|
|
return __mutex_owner(lock) != NULL;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
|
|
#endif /* __LINUX_MUTEX_H */
|