From 714493cd5468f42ca3c4f730a9c17c203abd5059 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 11 Apr 2008 15:23:52 -0400 Subject: Improve semaphore documentation Move documentation from semaphore.h to semaphore.c as requested by Andrew Morton. Also reformat to kernel-doc style and add some more notes about the implementation. Signed-off-by: Matthew Wilcox --- include/linux/semaphore.h | 39 ++------------------------------------- 1 file changed, 2 insertions(+), 37 deletions(-) (limited to 'include/linux') diff --git a/include/linux/semaphore.h b/include/linux/semaphore.h index a7125daaff90..9cae64b00d6b 100644 --- a/include/linux/semaphore.h +++ b/include/linux/semaphore.h @@ -4,8 +4,7 @@ * * Distributed under the terms of the GNU GPL, version 2 * - * Counting semaphores allow up to tasks to acquire the semaphore - * simultaneously. + * Please see kernel/semaphore.c for documentation of these functions */ #ifndef __LINUX_SEMAPHORE_H #define __LINUX_SEMAPHORE_H @@ -13,11 +12,7 @@ #include #include -/* - * The spinlock controls access to the other members of the semaphore. - * 'count' represents how many more tasks can acquire this semaphore. - * Tasks waiting for the lock are kept on the wait_list. - */ +/* Please don't access any members of this structure directly */ struct semaphore { spinlock_t lock; unsigned int count; @@ -46,41 +41,11 @@ static inline void sema_init(struct semaphore *sem, int val) #define init_MUTEX(sem) sema_init(sem, 1) #define init_MUTEX_LOCKED(sem) sema_init(sem, 0) -/* - * Attempt to acquire the semaphore. If another task is already holding the - * semaphore, sleep until the semaphore is released. - */ extern void down(struct semaphore *sem); - -/* - * As down(), except the sleep may be interrupted by a signal. If it is, - * this function will return -EINTR. - */ extern int __must_check down_interruptible(struct semaphore *sem); - -/* - * As down_interruptible(), except the sleep may only be interrupted by - * signals which are fatal to this process. - */ extern int __must_check down_killable(struct semaphore *sem); - -/* - * As down(), except this function will not sleep. It will return 0 if it - * acquired the semaphore and 1 if the semaphore was contended. This - * function may be called from any context, including interrupt and softirq. - */ extern int __must_check down_trylock(struct semaphore *sem); - -/* - * As down(), except this function will return -ETIME if it fails to - * acquire the semaphore within the specified number of jiffies. - */ extern int __must_check down_timeout(struct semaphore *sem, long jiffies); - -/* - * Release the semaphore. Unlike mutexes, up() may be called from any - * context and even by tasks which have never called down(). - */ extern void up(struct semaphore *sem); #endif /* __LINUX_SEMAPHORE_H */ -- cgit v1.2.2