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-frv/semaphore.h | 156 +------------------------------------------- 1 file changed, 1 insertion(+), 155 deletions(-) (limited to 'include/asm-frv') diff --git a/include/asm-frv/semaphore.h b/include/asm-frv/semaphore.h index d7aaa19..d9b2034 100644 --- a/include/asm-frv/semaphore.h +++ b/include/asm-frv/semaphore.h @@ -1,155 +1 @@ -/* semaphore.h: semaphores for the FR-V - * - * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved. - * Written by David Howells (dhowells@redhat.com) - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License - * as published by the Free Software Foundation; either version - * 2 of the License, or (at your option) any later version. - */ -#ifndef _ASM_SEMAPHORE_H -#define _ASM_SEMAPHORE_H - -#define RW_LOCK_BIAS 0x01000000 - -#ifndef __ASSEMBLY__ - -#include -#include -#include -#include - -/* - * the semaphore definition - * - if counter is >0 then there are tokens available on the semaphore for down to collect - * - if counter is <=0 then there are no spare tokens, and anyone that wants one must wait - * - if wait_list is not empty, then there are processes waiting for the semaphore - */ -struct semaphore { - unsigned counter; - spinlock_t wait_lock; - struct list_head wait_list; -#ifdef CONFIG_DEBUG_SEMAPHORE - unsigned __magic; -#endif -}; - -#ifdef CONFIG_DEBUG_SEMAPHORE -# define __SEM_DEBUG_INIT(name) , (long)&(name).__magic -#else -# define __SEM_DEBUG_INIT(name) -#endif - - -#define __SEMAPHORE_INITIALIZER(name,count) \ -{ count, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __SEM_DEBUG_INIT(name) } - -#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) -{ - *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val); -} - -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); -} - -extern void __down(struct semaphore *sem, unsigned long flags); -extern int __down_interruptible(struct semaphore *sem, unsigned long flags); -extern void __up(struct semaphore *sem); - -static inline void down(struct semaphore *sem) -{ - unsigned long flags; - -#ifdef CONFIG_DEBUG_SEMAPHORE - CHECK_MAGIC(sem->__magic); -#endif - - spin_lock_irqsave(&sem->wait_lock, flags); - if (likely(sem->counter > 0)) { - sem->counter--; - spin_unlock_irqrestore(&sem->wait_lock, flags); - } - else { - __down(sem, flags); - } -} - -static inline int down_interruptible(struct semaphore *sem) -{ - unsigned long flags; - int ret = 0; - -#ifdef CONFIG_DEBUG_SEMAPHORE - CHECK_MAGIC(sem->__magic); -#endif - - spin_lock_irqsave(&sem->wait_lock, flags); - if (likely(sem->counter > 0)) { - sem->counter--; - spin_unlock_irqrestore(&sem->wait_lock, flags); - } - else { - ret = __down_interruptible(sem, flags); - } - return ret; -} - -/* - * non-blockingly attempt to down() a semaphore. - * - returns zero if we acquired it - */ -static inline int down_trylock(struct semaphore *sem) -{ - unsigned long flags; - int success = 0; - -#ifdef CONFIG_DEBUG_SEMAPHORE - CHECK_MAGIC(sem->__magic); -#endif - - spin_lock_irqsave(&sem->wait_lock, flags); - if (sem->counter > 0) { - sem->counter--; - success = 1; - } - spin_unlock_irqrestore(&sem->wait_lock, flags); - return !success; -} - -static inline void up(struct semaphore *sem) -{ - unsigned long flags; - -#ifdef CONFIG_DEBUG_SEMAPHORE - CHECK_MAGIC(sem->__magic); -#endif - - spin_lock_irqsave(&sem->wait_lock, flags); - if (!list_empty(&sem->wait_list)) - __up(sem); - else - sem->counter++; - spin_unlock_irqrestore(&sem->wait_lock, flags); -} - -static inline int sem_getcount(struct semaphore *sem) -{ - return sem->counter; -} - -#endif /* __ASSEMBLY__ */ - -#endif +#include -- cgit v1.1