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>
diff --git a/include/asm-mips/semaphore.h b/include/asm-mips/semaphore.h
index fdf8042..d9b2034 100644
--- a/include/asm-mips/semaphore.h
+++ b/include/asm-mips/semaphore.h
@@ -1,108 +1 @@
-/*
- * This file is subject to the terms and conditions of the GNU General Public
- * License. See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 1996 Linus Torvalds
- * Copyright (C) 1998, 99, 2000, 01, 04 Ralf Baechle
- * Copyright (C) 1999, 2000, 01 Silicon Graphics, Inc.
- * Copyright (C) 2000, 01 MIPS Technologies, Inc.
- *
- * In all honesty, little of the old MIPS code left - the PPC64 variant was
- * just looking nice and portable so I ripped it. Credits to whoever wrote
- * it.
- */
-#ifndef __ASM_SEMAPHORE_H
-#define __ASM_SEMAPHORE_H
-
-/*
- * Remove spinlock-based RW semaphores; RW semaphore definitions are
- * now in rwsem.h and we use the generic lib/rwsem.c implementation.
- * Rework semaphores to use atomic_dec_if_positive.
- * -- Paul Mackerras (paulus@samba.org)
- */
-
-#ifdef __KERNEL__
-
-#include <asm/atomic.h>
-#include <asm/system.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, n) \
-{ \
- .count = ATOMIC_INIT(n), \
- .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)
-{
- 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);
-}
-
-extern void __down(struct semaphore * sem);
-extern int __down_interruptible(struct semaphore * sem);
-extern void __up(struct semaphore * sem);
-
-static inline void down(struct semaphore * sem)
-{
- might_sleep();
-
- /*
- * Try to get the semaphore, take the slow path if we fail.
- */
- if (unlikely(atomic_dec_return(&sem->count) < 0))
- __down(sem);
-}
-
-static inline int down_interruptible(struct semaphore * sem)
-{
- int ret = 0;
-
- might_sleep();
-
- if (unlikely(atomic_dec_return(&sem->count) < 0))
- ret = __down_interruptible(sem);
- return ret;
-}
-
-static inline int down_trylock(struct semaphore * sem)
-{
- return atomic_dec_if_positive(&sem->count) < 0;
-}
-
-static inline void up(struct semaphore * sem)
-{
- if (unlikely(atomic_inc_return(&sem->count) <= 0))
- __up(sem);
-}
-
-#endif /* __KERNEL__ */
-
-#endif /* __ASM_SEMAPHORE_H */
+#include <linux/semaphore.h>