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, 107 deletions

diff --git a/include/asm-s390/semaphore.h b/include/asm-s390/semaphore.h
index 0e7001ad8392..d9b2034ed1d2 100644
--- a/include/asm-s390/semaphore.h
+++ b/include/asm-s390/semaphore.h
@@ -1,107 +1 @@
-/*
- *  include/asm-s390/semaphore.h
- *
- *  S390 version
- *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
- *
- *  Derived from "include/asm-i386/semaphore.h"
- *    (C) Copyright 1996 Linus Torvalds
- */
-
-#ifndef _S390_SEMAPHORE_H
-#define _S390_SEMAPHORE_H
-
-#include <asm/system.h>
-#include <asm/atomic.h>
-#include <linux/wait.h>
-#include <linux/rwsem.h>
-
-struct semaphore {
-	/*
-	 * Note that any negative value of count is equivalent to 0,
-	 * but additionally indicates that some process(es) might be
-	 * sleeping on `wait'.
-	 */
-	atomic_t count;
-	wait_queue_head_t wait;
-};
-
-#define __SEMAPHORE_INITIALIZER(name,count) \
-	{ ATOMIC_INIT(count), __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);
-	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);
-
-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 old_val, new_val;
-
-	/*
-	 * This inline assembly atomically implements the equivalent
-	 * to the following C code:
-	 *   old_val = sem->count.counter;
-	 *   if ((new_val = old_val) > 0)
-	 *       sem->count.counter = --new_val;
-	 * In the ppc code this is called atomic_dec_if_positive.
-	 */
-	asm volatile(
-		"	l	%0,0(%3)\n"
-		"0:	ltr	%1,%0\n"
-		"	jle	1f\n"
-		"	ahi	%1,-1\n"
-		"	cs	%0,%1,0(%3)\n"
-		"	jl	0b\n"
-		"1:"
-		: "=&d" (old_val), "=&d" (new_val), "=m" (sem->count.counter)
-		: "a" (&sem->count.counter), "m" (sem->count.counter)
-		: "cc", "memory");
-	return old_val <= 0;
-}
-
-static inline void up(struct semaphore * sem)
-{
-	if (atomic_inc_return(&sem->count) <= 0)
-		__up(sem);
-}
-
-#endif
+#include <linux/semaphore.h>