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, 305 deletions

diff --git a/include/asm-m68k/semaphore-helper.h b/include/asm-m68k/semaphore-helper.h
deleted file mode 100644
index eef30ba0b49..00000000000
--- a/include/asm-m68k/semaphore-helper.h
+++ /dev/null
@@ -1,142 +0,0 @@
-#ifndef _M68K_SEMAPHORE_HELPER_H
-#define _M68K_SEMAPHORE_HELPER_H
-
-/*
- * SMP- and interrupt-safe semaphores helper functions.
- *
- * (C) Copyright 1996 Linus Torvalds
- *
- * m68k version by Andreas Schwab
- */
-
-#include <linux/errno.h>
-
-/*
- * These two _must_ execute atomically wrt each other.
- */
-static inline void wake_one_more(struct semaphore * sem)
-{
-	atomic_inc(&sem->waking);
-}
-
-#ifndef CONFIG_RMW_INSNS
-extern spinlock_t semaphore_wake_lock;
-#endif
-
-static inline int waking_non_zero(struct semaphore *sem)
-{
-	int ret;
-#ifndef CONFIG_RMW_INSNS
-	unsigned long flags;
-
-	spin_lock_irqsave(&semaphore_wake_lock, flags);
-	ret = 0;
-	if (atomic_read(&sem->waking) > 0) {
-		atomic_dec(&sem->waking);
-		ret = 1;
-	}
-	spin_unlock_irqrestore(&semaphore_wake_lock, flags);
-#else
-	int tmp1, tmp2;
-
-	__asm__ __volatile__
-	  ("1:	movel	%1,%2\n"
-	   "    jle	2f\n"
-	   "	subql	#1,%2\n"
-	   "	casl	%1,%2,%3\n"
-	   "	jne	1b\n"
-	   "	moveq	#1,%0\n"
-	   "2:"
-	   : "=d" (ret), "=d" (tmp1), "=d" (tmp2)
-	   : "m" (sem->waking), "0" (0), "1" (sem->waking));
-#endif
-
-	return ret;
-}
-
-/*
- * waking_non_zero_interruptible:
- *	1	got the lock
- *	0	go to sleep
- *	-EINTR	interrupted
- */
-static inline int waking_non_zero_interruptible(struct semaphore *sem,
-						struct task_struct *tsk)
-{
-	int ret;
-#ifndef CONFIG_RMW_INSNS
-	unsigned long flags;
-
-	spin_lock_irqsave(&semaphore_wake_lock, flags);
-	ret = 0;
-	if (atomic_read(&sem->waking) > 0) {
-		atomic_dec(&sem->waking);
-		ret = 1;
-	} else if (signal_pending(tsk)) {
-		atomic_inc(&sem->count);
-		ret = -EINTR;
-	}
-	spin_unlock_irqrestore(&semaphore_wake_lock, flags);
-#else
-	int tmp1, tmp2;
-
-	__asm__ __volatile__
-	  ("1:	movel	%1,%2\n"
-	   "	jle	2f\n"
-	   "	subql	#1,%2\n"
-	   "	casl	%1,%2,%3\n"
-	   "	jne	1b\n"
-	   "	moveq	#1,%0\n"
-	   "	jra	%a4\n"
-	   "2:"
-	   : "=d" (ret), "=d" (tmp1), "=d" (tmp2)
-	   : "m" (sem->waking), "i" (&&next), "0" (0), "1" (sem->waking));
-	if (signal_pending(tsk)) {
-		atomic_inc(&sem->count);
-		ret = -EINTR;
-	}
-next:
-#endif
-
-	return ret;
-}
-
-/*
- * waking_non_zero_trylock:
- *	1	failed to lock
- *	0	got the lock
- */
-static inline int waking_non_zero_trylock(struct semaphore *sem)
-{
-	int ret;
-#ifndef CONFIG_RMW_INSNS
-	unsigned long flags;
-
-	spin_lock_irqsave(&semaphore_wake_lock, flags);
-	ret = 1;
-	if (atomic_read(&sem->waking) > 0) {
-		atomic_dec(&sem->waking);
-		ret = 0;
-	} else
-		atomic_inc(&sem->count);
-	spin_unlock_irqrestore(&semaphore_wake_lock, flags);
-#else
-	int tmp1, tmp2;
-
-	__asm__ __volatile__
-	  ("1:	movel	%1,%2\n"
-	   "    jle	2f\n"
-	   "	subql	#1,%2\n"
-	   "	casl	%1,%2,%3\n"
-	   "	jne	1b\n"
-	   "	moveq	#0,%0\n"
-	   "2:"
-	   : "=d" (ret), "=d" (tmp1), "=d" (tmp2)
-	   : "m" (sem->waking), "0" (1), "1" (sem->waking));
-	if (ret)
-		atomic_inc(&sem->count);
-#endif
-	return ret;
-}
-
-#endif
diff --git a/include/asm-m68k/semaphore.h b/include/asm-m68k/semaphore.h
index 64d6b119bb0..d9b2034ed1d 100644
--- a/include/asm-m68k/semaphore.h
+++ b/include/asm-m68k/semaphore.h
@@ -1,163 +1 @@
-#ifndef _M68K_SEMAPHORE_H
-#define _M68K_SEMAPHORE_H
-
-#define RW_LOCK_BIAS		 0x01000000
-
-#ifndef __ASSEMBLY__
-
-#include <linux/linkage.h>
-#include <linux/wait.h>
-#include <linux/spinlock.h>
-#include <linux/rwsem.h>
-#include <linux/stringify.h>
-
-#include <asm/system.h>
-#include <asm/atomic.h>
-
-/*
- * Interrupt-safe semaphores..
- *
- * (C) Copyright 1996 Linus Torvalds
- *
- * m68k version by Andreas Schwab
- */
-
-
-struct semaphore {
-	atomic_t count;
-	atomic_t waking;
-	wait_queue_head_t wait;
-};
-
-#define __SEMAPHORE_INITIALIZER(name, n)				\
-{									\
-	.count		= ATOMIC_INIT(n),				\
-	.waking		= ATOMIC_INIT(0),				\
-	.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);
-}
-
-asmlinkage void __down_failed(void /* special register calling convention */);
-asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
-asmlinkage int  __down_failed_trylock(void  /* params in registers */);
-asmlinkage void __up_wakeup(void /* special register calling convention */);
-
-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);
-
-/*
- * This is ugly, but we want the default case to fall through.
- * "down_failed" is a special asm handler that calls the C
- * routine that actually waits. See arch/m68k/lib/semaphore.S
- */
-static inline void down(struct semaphore *sem)
-{
-	register struct semaphore *sem1 __asm__ ("%a1") = sem;
-
-	might_sleep();
-	__asm__ __volatile__(
-		"| atomic down operation\n\t"
-		"subql #1,%0@\n\t"
-		"jmi 2f\n\t"
-		"1:\n"
-		LOCK_SECTION_START(".even\n\t")
-		"2:\tpea 1b\n\t"
-		"jbra __down_failed\n"
-		LOCK_SECTION_END
-		: /* no outputs */
-		: "a" (sem1)
-		: "memory");
-}
-
-static inline int down_interruptible(struct semaphore *sem)
-{
-	register struct semaphore *sem1 __asm__ ("%a1") = sem;
-	register int result __asm__ ("%d0");
-
-	might_sleep();
-	__asm__ __volatile__(
-		"| atomic interruptible down operation\n\t"
-		"subql #1,%1@\n\t"
-		"jmi 2f\n\t"
-		"clrl %0\n"
-		"1:\n"
-		LOCK_SECTION_START(".even\n\t")
-		"2:\tpea 1b\n\t"
-		"jbra __down_failed_interruptible\n"
-		LOCK_SECTION_END
-		: "=d" (result)
-		: "a" (sem1)
-		: "memory");
-	return result;
-}
-
-static inline int down_trylock(struct semaphore *sem)
-{
-	register struct semaphore *sem1 __asm__ ("%a1") = sem;
-	register int result __asm__ ("%d0");
-
-	__asm__ __volatile__(
-		"| atomic down trylock operation\n\t"
-		"subql #1,%1@\n\t"
-		"jmi 2f\n\t"
-		"clrl %0\n"
-		"1:\n"
-		LOCK_SECTION_START(".even\n\t")
-		"2:\tpea 1b\n\t"
-		"jbra __down_failed_trylock\n"
-		LOCK_SECTION_END
-		: "=d" (result)
-		: "a" (sem1)
-		: "memory");
-	return result;
-}
-
-/*
- * Note! This is subtle. We jump to wake people up only if
- * the semaphore was negative (== somebody was waiting on it).
- * The default case (no contention) will result in NO
- * jumps for both down() and up().
- */
-static inline void up(struct semaphore *sem)
-{
-	register struct semaphore *sem1 __asm__ ("%a1") = sem;
-
-	__asm__ __volatile__(
-		"| atomic up operation\n\t"
-		"addql #1,%0@\n\t"
-		"jle 2f\n"
-		"1:\n"
-		LOCK_SECTION_START(".even\n\t")
-		"2:\t"
-		"pea 1b\n\t"
-		"jbra __up_wakeup\n"
-		LOCK_SECTION_END
-		: /* no outputs */
-		: "a" (sem1)
-		: "memory");
-}
-
-#endif /* __ASSEMBLY__ */
-
-#endif
+#include <linux/semaphore.h>