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-mn10300/semaphore.h b/include/asm-mn10300/semaphore.h
index 5a9e1ad..d9b2034 100644
--- a/include/asm-mn10300/semaphore.h
+++ b/include/asm-mn10300/semaphore.h
@@ -1,169 +1 @@
-/* MN10300 Semaphores
- *
- * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public Licence
- * as published by the Free Software Foundation; either version
- * 2 of the Licence, or (at your option) any later version.
- */
-#ifndef _ASM_SEMAPHORE_H
-#define _ASM_SEMAPHORE_H
-
-#ifndef __ASSEMBLY__
-
-#include <linux/linkage.h>
-#include <linux/wait.h>
-#include <linux/spinlock.h>
-#include <linux/rwsem.h>
-
-#define SEMAPHORE_DEBUG 0
-
-/*
- * the semaphore definition
- * - if count is >0 then there are tokens available on the semaphore for down
- * to collect
- * - if count is <=0 then there are no spare tokens, and anyone that wants one
- * must wait
- * - if wait_list is not empty, then there are processes waiting for the
- * semaphore
- */
-struct semaphore {
- atomic_t count; /* it's not really atomic, it's
- * just that certain modules
- * expect to be able to access
- * it directly */
- spinlock_t wait_lock;
- struct list_head wait_list;
-#if SEMAPHORE_DEBUG
- unsigned __magic;
-#endif
-};
-
-#if SEMAPHORE_DEBUG
-# define __SEM_DEBUG_INIT(name) , (long)&(name).__magic
-#else
-# define __SEM_DEBUG_INIT(name)
-#endif
-
-
-#define __SEMAPHORE_INITIALIZER(name, init_count) \
-{ \
- .count = ATOMIC_INIT(init_count), \
- .wait_lock = __SPIN_LOCK_UNLOCKED((name).wait_lock), \
- .wait_list = LIST_HEAD_INIT((name).wait_list) \
- __SEM_DEBUG_INIT(name) \
-}
-
-#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
- struct semaphore name = __SEMAPHORE_INITIALIZER(name, count)
-
-#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1)
-#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0)
-
-static inline void sema_init(struct semaphore *sem, int val)
-{
- *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
-}
-
-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, unsigned long flags);
-extern int __down_interruptible(struct semaphore *sem, unsigned long flags);
-extern void __up(struct semaphore *sem);
-
-static inline void down(struct semaphore *sem)
-{
- unsigned long flags;
- int count;
-
-#if SEMAPHORE_DEBUG
- CHECK_MAGIC(sem->__magic);
-#endif
-
- spin_lock_irqsave(&sem->wait_lock, flags);
- count = atomic_read(&sem->count);
- if (likely(count > 0)) {
- atomic_set(&sem->count, count - 1);
- spin_unlock_irqrestore(&sem->wait_lock, flags);
- } else {
- __down(sem, flags);
- }
-}
-
-static inline int down_interruptible(struct semaphore *sem)
-{
- unsigned long flags;
- int count, ret = 0;
-
-#if SEMAPHORE_DEBUG
- CHECK_MAGIC(sem->__magic);
-#endif
-
- spin_lock_irqsave(&sem->wait_lock, flags);
- count = atomic_read(&sem->count);
- if (likely(count > 0)) {
- atomic_set(&sem->count, count - 1);
- spin_unlock_irqrestore(&sem->wait_lock, flags);
- } else {
- ret = __down_interruptible(sem, flags);
- }
- return ret;
-}
-
-/*
- * non-blockingly attempt to down() a semaphore.
- * - returns zero if we acquired it
- */
-static inline int down_trylock(struct semaphore *sem)
-{
- unsigned long flags;
- int count, success = 0;
-
-#if SEMAPHORE_DEBUG
- CHECK_MAGIC(sem->__magic);
-#endif
-
- spin_lock_irqsave(&sem->wait_lock, flags);
- count = atomic_read(&sem->count);
- if (likely(count > 0)) {
- atomic_set(&sem->count, count - 1);
- success = 1;
- }
- spin_unlock_irqrestore(&sem->wait_lock, flags);
- return !success;
-}
-
-static inline void up(struct semaphore *sem)
-{
- unsigned long flags;
-
-#if SEMAPHORE_DEBUG
- CHECK_MAGIC(sem->__magic);
-#endif
-
- spin_lock_irqsave(&sem->wait_lock, flags);
- if (!list_empty(&sem->wait_list))
- __up(sem);
- else
- atomic_set(&sem->count, atomic_read(&sem->count) + 1);
- spin_unlock_irqrestore(&sem->wait_lock, flags);
-}
-
-static inline int sem_getcount(struct semaphore *sem)
-{
- return atomic_read(&sem->count);
-}
-
-#endif /* __ASSEMBLY__ */
-
-#endif
+#include <linux/semaphore.h>