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 <willy@linux.intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 115 deletions

diff --git a/include/asm-sh/semaphore.h b/include/asm-sh/semaphore.h
index 9e5a37c4dce..d9b2034ed1d 100644
--- a/include/asm-sh/semaphore.h
+++ b/include/asm-sh/semaphore.h
@@ -1,115 +1 @@
-#ifndef __ASM_SH_SEMAPHORE_H
-#define __ASM_SH_SEMAPHORE_H
-
-#include <linux/linkage.h>
-
-#ifdef __KERNEL__
-/*
- * SMP- and interrupt-safe semaphores.
- *
- * (C) Copyright 1996 Linus Torvalds
- *
- * SuperH verison by Niibe Yutaka
- *  (Currently no asm implementation but generic C code...)
- */
-
-#include <linux/spinlock.h>
-#include <linux/rwsem.h>
-#include <linux/wait.h>
-
-#include <asm/system.h>
-#include <asm/atomic.h>
-
-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)
-{
-/*
- *	*sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
- *
- * i'd rather use the more flexible initialization above, but sadly
- * GCC 2.7.2.3 emits a bogus warning. EGCS doesn't. Oh well.
- */
-	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);
-}
-
-#if 0
-asmlinkage void __down_failed(void /* special register calling convention */);
-asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
-asmlinkage int  __down_failed_trylock(void  /* params in registers */);
-asmlinkage void __up_wakeup(void /* special register calling convention */);
-#endif
-
-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_dec_return(&sem->count) < 0)
-		__down(sem);
-}
-
-static inline int down_interruptible(struct semaphore * sem)
-{
-	int ret = 0;
-
-	might_sleep();
-	if (atomic_dec_return(&sem->count) < 0)
-		ret = __down_interruptible(sem);
-	return ret;
-}
-
-static inline int down_trylock(struct semaphore * sem)
-{
-	int ret = 0;
-
-	if (atomic_dec_return(&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_inc_return(&sem->count) <= 0)
-		__up(sem);
-}
-
-#endif
-#endif /* __ASM_SH_SEMAPHORE_H */
+#include <linux/semaphore.h>