| 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 |