diff options
author | Ingo Molnar <mingo@elte.hu> | 2006-01-09 15:59:19 -0800 |
---|---|---|
committer | Ingo Molnar <mingo@hera.kernel.org> | 2006-01-09 15:59:19 -0800 |
commit | 6053ee3b32e3437e8c1e72687850f436e779bd49 (patch) | |
tree | bb845004eb66554c569bc53a1efc87365c8a3cbe /include/linux/mutex.h | |
parent | 2acbb8c657af86b2fa5b185f1d7048385e310585 (diff) | |
download | linux-stable-6053ee3b32e3437e8c1e72687850f436e779bd49.tar.gz linux-stable-6053ee3b32e3437e8c1e72687850f436e779bd49.tar.bz2 linux-stable-6053ee3b32e3437e8c1e72687850f436e779bd49.zip |
[PATCH] mutex subsystem, core
mutex implementation, core files: just the basic subsystem, no users of it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Diffstat (limited to 'include/linux/mutex.h')
-rw-r--r-- | include/linux/mutex.h | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/include/linux/mutex.h b/include/linux/mutex.h new file mode 100644 index 000000000000..9bce0fee68d4 --- /dev/null +++ b/include/linux/mutex.h @@ -0,0 +1,119 @@ +/* + * 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 <linux/list.h> +#include <linux/spinlock_types.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 irq contexts + * + * 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; + spinlock_t wait_lock; + struct list_head wait_list; +#ifdef CONFIG_DEBUG_MUTEXES + struct thread_info *owner; + struct list_head held_list; + unsigned long acquire_ip; + const char *name; + void *magic; +#endif +}; + +/* + * 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; +#ifdef CONFIG_DEBUG_MUTEXES + struct mutex *lock; + void *magic; +#endif +}; + +#ifdef CONFIG_DEBUG_MUTEXES +# include <linux/mutex-debug.h> +#else +# define __DEBUG_MUTEX_INITIALIZER(lockname) +# define mutex_init(mutex) __mutex_init(mutex, NULL) +# define mutex_destroy(mutex) do { } while (0) +# define mutex_debug_show_all_locks() do { } while (0) +# define mutex_debug_show_held_locks(p) do { } while (0) +# define mutex_debug_check_no_locks_held(task) do { } while (0) +# define mutex_debug_check_no_locks_freed(from, to) do { } while (0) +#endif + +#define __MUTEX_INITIALIZER(lockname) \ + { .count = ATOMIC_INIT(1) \ + , .wait_lock = SPIN_LOCK_UNLOCKED \ + , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ + __DEBUG_MUTEX_INITIALIZER(lockname) } + +#define DEFINE_MUTEX(mutexname) \ + struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) + +extern void fastcall __mutex_init(struct mutex *lock, const char *name); + +/*** + * 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 fastcall mutex_is_locked(struct mutex *lock) +{ + return atomic_read(&lock->count) != 1; +} + +/* + * See kernel/mutex.c for detailed documentation of these APIs. + * Also see Documentation/mutex-design.txt. + */ +extern void fastcall mutex_lock(struct mutex *lock); +extern int fastcall mutex_lock_interruptible(struct mutex *lock); +/* + * NOTE: mutex_trylock() follows the spin_trylock() convention, + * not the down_trylock() convention! + */ +extern int fastcall mutex_trylock(struct mutex *lock); +extern void fastcall mutex_unlock(struct mutex *lock); + +#endif |