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, 169 deletions

diff --git a/include/asm-mn10300/semaphore.h b/include/asm-mn10300/semaphore.h
index 5a9e1ad0b253..d9b2034ed1d2 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>