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>

2 files changed, 1 insertions, 234 deletions

diff --git a/include/asm-parisc/semaphore-helper.h b/include/asm-parisc/semaphore-helper.h
deleted file mode 100644
index 387f7c1..0000000
--- a/include/asm-parisc/semaphore-helper.h
+++ /dev/null
@@ -1,89 +0,0 @@
-#ifndef _ASM_PARISC_SEMAPHORE_HELPER_H
-#define _ASM_PARISC_SEMAPHORE_HELPER_H
-
-/*
- * SMP- and interrupt-safe semaphores helper functions.
- *
- * (C) Copyright 1996 Linus Torvalds
- * (C) Copyright 1999 Andrea Arcangeli
- */
-
-/*
- * These two _must_ execute atomically wrt each other.
- *
- * This is trivially done with load_locked/store_cond,
- * which we have.  Let the rest of the losers suck eggs.
- */
-static __inline__ void wake_one_more(struct semaphore * sem)
-{
-	atomic_inc((atomic_t *)&sem->waking);
-}
-
-static __inline__ int waking_non_zero(struct semaphore *sem)
-{
-	unsigned long flags;
-	int ret = 0;
-
-	spin_lock_irqsave(&semaphore_wake_lock, flags);
-	if (sem->waking > 0) {
-		sem->waking--;
-		ret = 1;
-	}
-	spin_unlock_irqrestore(&semaphore_wake_lock, flags);
-	return ret;
-}
-
-/*
- * waking_non_zero_interruptible:
- *	1	got the lock
- *	0	go to sleep
- *	-EINTR	interrupted
- *
- * We must undo the sem->count down_interruptible() increment while we are
- * protected by the spinlock in order to make atomic this atomic_inc() with the
- * atomic_read() in wake_one_more(), otherwise we can race. -arca
- */
-static __inline__ int waking_non_zero_interruptible(struct semaphore *sem,
-						struct task_struct *tsk)
-{
-	unsigned long flags;
-	int ret = 0;
-
-	spin_lock_irqsave(&semaphore_wake_lock, flags);
-	if (sem->waking > 0) {
-		sem->waking--;
-		ret = 1;
-	} else if (signal_pending(tsk)) {
-		atomic_inc(&sem->count);
-		ret = -EINTR;
-	}
-	spin_unlock_irqrestore(&semaphore_wake_lock, flags);
-	return ret;
-}
-
-/*
- * waking_non_zero_trylock:
- *	1	failed to lock
- *	0	got the lock
- *
- * We must undo the sem->count down_trylock() increment while we are
- * protected by the spinlock in order to make atomic this atomic_inc() with the
- * atomic_read() in wake_one_more(), otherwise we can race. -arca
- */
-static __inline__ int waking_non_zero_trylock(struct semaphore *sem)
-{
-	unsigned long flags;
-	int ret = 1;
-
-	spin_lock_irqsave(&semaphore_wake_lock, flags);
-	if (sem->waking <= 0)
-		atomic_inc(&sem->count);
-	else {
-		sem->waking--;
-		ret = 0;
-	}
-	spin_unlock_irqrestore(&semaphore_wake_lock, flags);
-	return ret;
-}
-
-#endif /* _ASM_PARISC_SEMAPHORE_HELPER_H */
diff --git a/include/asm-parisc/semaphore.h b/include/asm-parisc/semaphore.h
index a16271c..d9b2034 100644
--- a/include/asm-parisc/semaphore.h
+++ b/include/asm-parisc/semaphore.h
@@ -1,145 +1 @@
-/*    SMP- and interrupt-safe semaphores.
- *    PA-RISC version by Matthew Wilcox
- *
- *    Linux/PA-RISC Project (http://www.parisc-linux.org/)
- *    Copyright (C) 1996 Linus Torvalds
- *    Copyright (C) 1999-2001 Matthew Wilcox < willy at debian d0T org >
- *    Copyright (C) 2000 Grant Grundler < grundler a debian org >
- *
- *    This program is free software; you can redistribute it and/or modify
- *    it under the terms of the GNU General Public License as published by
- *    the Free Software Foundation; either version 2 of the License, or
- *    (at your option) any later version.
- *
- *    This program is distributed in the hope that it will be useful,
- *    but WITHOUT ANY WARRANTY; without even the implied warranty of
- *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *    GNU General Public License for more details.
- *
- *    You should have received a copy of the GNU General Public License
- *    along with this program; if not, write to the Free Software
- *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- */
-
-#ifndef _ASM_PARISC_SEMAPHORE_H
-#define _ASM_PARISC_SEMAPHORE_H
-
-#include <linux/spinlock.h>
-#include <linux/wait.h>
-#include <linux/rwsem.h>
-
-#include <asm/system.h>
-
-/*
- * The `count' is initialised to the number of people who are allowed to
- * take the lock.  (Normally we want a mutex, so this is `1').  if
- * `count' is positive, the lock can be taken.  if it's 0, no-one is
- * waiting on it.  if it's -1, at least one task is waiting.
- */
-struct semaphore {
-	spinlock_t	sentry;
-	int		count;
-	wait_queue_head_t wait;
-};
-
-#define __SEMAPHORE_INITIALIZER(name, n)				\
-{									\
-	.sentry		= SPIN_LOCK_UNLOCKED,				\
-	.count		= 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)
-{
-	*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);
-}
-
-static inline int sem_getcount(struct semaphore *sem)
-{
-	return sem->count;
-}
-
-asmlinkage void __down(struct semaphore * sem);
-asmlinkage int  __down_interruptible(struct semaphore * sem);
-asmlinkage void __up(struct semaphore * sem);
-
-/* Semaphores can be `tried' from irq context.  So we have to disable
- * interrupts while we're messing with the semaphore.  Sorry.
- */
-
-static inline void down(struct semaphore * sem)
-{
-	might_sleep();
-	spin_lock_irq(&sem->sentry);
-	if (sem->count > 0) {
-		sem->count--;
-	} else {
-		__down(sem);
-	}
-	spin_unlock_irq(&sem->sentry);
-}
-
-static inline int down_interruptible(struct semaphore * sem)
-{
-	int ret = 0;
-	might_sleep();
-	spin_lock_irq(&sem->sentry);
-	if (sem->count > 0) {
-		sem->count--;
-	} else {
-		ret = __down_interruptible(sem);
-	}
-	spin_unlock_irq(&sem->sentry);
-	return ret;
-}
-
-/*
- * down_trylock returns 0 on success, 1 if we failed to get the lock.
- * May not sleep, but must preserve irq state
- */
-static inline int down_trylock(struct semaphore * sem)
-{
-	unsigned long flags;
-	int count;
-
-	spin_lock_irqsave(&sem->sentry, flags);
-	count = sem->count - 1;
-	if (count >= 0)
-		sem->count = count;
-	spin_unlock_irqrestore(&sem->sentry, flags);
-	return (count < 0);
-}
-
-/*
- * 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)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&sem->sentry, flags);
-	if (sem->count < 0) {
-		__up(sem);
-	} else {
-		sem->count++;
-	}
-	spin_unlock_irqrestore(&sem->sentry, flags);
-}
-
-#endif /* _ASM_PARISC_SEMAPHORE_H */
+#include <linux/semaphore.h>