From 64ac24e738823161693bf791f87adc802cf529ff Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 7 Mar 2008 21:55:58 -0500 Subject: Generic semaphore implementation Semaphores are no longer performance-critical, so a generic C implementation is better for maintainability, debuggability and extensibility. Thanks to Peter Zijlstra for fixing the lockdep warning. Thanks to Harvey Harrison for pointing out that the unlikely() was unnecessary. Signed-off-by: Matthew Wilcox Acked-by: Ingo Molnar --- include/asm-xtensa/semaphore.h | 100 +---------------------------------------- 1 file changed, 1 insertion(+), 99 deletions(-) (limited to 'include/asm-xtensa') diff --git a/include/asm-xtensa/semaphore.h b/include/asm-xtensa/semaphore.h index 3e04167cd9d..d9b2034ed1d 100644 --- a/include/asm-xtensa/semaphore.h +++ b/include/asm-xtensa/semaphore.h @@ -1,99 +1 @@ -/* - * linux/include/asm-xtensa/semaphore.h - * - * This file is subject to the terms and conditions of the GNU General Public - * License. See the file "COPYING" in the main directory of this archive - * for more details. - * - * Copyright (C) 2001 - 2005 Tensilica Inc. - */ - -#ifndef _XTENSA_SEMAPHORE_H -#define _XTENSA_SEMAPHORE_H - -#include -#include -#include -#include - -struct semaphore { - atomic_t count; - int sleepers; - wait_queue_head_t wait; -}; - -#define __SEMAPHORE_INITIALIZER(name,n) \ -{ \ - .count = ATOMIC_INIT(n), \ - .sleepers = 0, \ - .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ -} - -#define __DECLARE_SEMAPHORE_GENERIC(name,count) \ - struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) - -#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) - -static inline void sema_init (struct semaphore *sem, int val) -{ - atomic_set(&sem->count, val); - sem->sleepers = 0; - init_waitqueue_head(&sem->wait); -} - -static inline void init_MUTEX (struct semaphore *sem) -{ - sema_init(sem, 1); -} - -static inline void init_MUTEX_LOCKED (struct semaphore *sem) -{ - sema_init(sem, 0); -} - -asmlinkage void __down(struct semaphore * sem); -asmlinkage int __down_interruptible(struct semaphore * sem); -asmlinkage int __down_trylock(struct semaphore * sem); -asmlinkage void __up(struct semaphore * sem); - -extern spinlock_t semaphore_wake_lock; - -static inline void down(struct semaphore * sem) -{ - might_sleep(); - - if (atomic_sub_return(1, &sem->count) < 0) - __down(sem); -} - -static inline int down_interruptible(struct semaphore * sem) -{ - int ret = 0; - - might_sleep(); - - if (atomic_sub_return(1, &sem->count) < 0) - ret = __down_interruptible(sem); - return ret; -} - -static inline int down_trylock(struct semaphore * sem) -{ - int ret = 0; - - if (atomic_sub_return(1, &sem->count) < 0) - ret = __down_trylock(sem); - return ret; -} - -/* - * Note! This is subtle. We jump to wake people up only if - * the semaphore was negative (== somebody was waiting on it). - */ -static inline void up(struct semaphore * sem) -{ - if (atomic_add_return(1, &sem->count) <= 0) - __up(sem); -} - -#endif /* _XTENSA_SEMAPHORE_H */ +#include -- cgit v1.2.3