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 <willy@linux.intel.com>
diff --git a/include/linux/semaphore.h b/include/linux/semaphore.h
index a7125da..9cae64b 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 <n> 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 <linux/list.h>
#include <linux/spinlock.h>
-/*
- * 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 @@
#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 */