0,0 → 1,86 |
/* |
* 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 <kernel.h> |
#include <linux/list.h> |
#include <asm/atomic.h> |
|
/* |
* 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 { |
/* 1: unlocked, 0: locked, negative: locked, possible waiters */ |
atomic_t count; |
struct list_head wait_list; |
}; |
|
/* |
* 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; |
int *task; |
}; |
|
|
#define __MUTEX_INITIALIZER(lockname) \ |
{ .count = ATOMIC_INIT(1) \ |
, .wait_list = LIST_HEAD_INIT(lockname.wait_list) } |
|
#define DEFINE_MUTEX(mutexname) \ |
struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) |
|
void __attribute__ ((fastcall)) __attribute__ ((dllimport)) |
mutex_init(struct mutex*)__asm__("MutexInit"); |
void __attribute__ ((fastcall)) __attribute__ ((dllimport)) |
mutex_lock(struct mutex*)__asm__("MutexLock"); |
void __attribute__ ((fastcall)) __attribute__ ((dllimport)) |
mutex_unlock(struct mutex*)__asm__("MutexUnlock"); |
|
/** |
* 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) |
{ |
return atomic_read(&lock->count) != 1; |
} |
|
#endif |