From 64ac24e738823161693bf791f87adc802cf529ff Mon Sep 17 00:00:00 2001
From: Matthew Wilcox <matthew@wil.cx>
Date: Fri, 7 Mar 2008 21:55:58 -0500
Subject: 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>
---
 arch/parisc/kernel/semaphore.c | 102 -----------------------------------------
 1 file changed, 102 deletions(-)
 delete mode 100644 arch/parisc/kernel/semaphore.c

(limited to 'arch/parisc/kernel/semaphore.c')

diff --git a/arch/parisc/kernel/semaphore.c b/arch/parisc/kernel/semaphore.c
deleted file mode 100644
index ee806bcc3726..000000000000
--- a/arch/parisc/kernel/semaphore.c
+++ /dev/null
@@ -1,102 +0,0 @@
-/*
- * Semaphore implementation Copyright (c) 2001 Matthew Wilcox, Hewlett-Packard
- */
-
-#include <linux/sched.h>
-#include <linux/spinlock.h>
-#include <linux/errno.h>
-#include <linux/init.h>
-
-/*
- * Semaphores are complex as we wish to avoid using two variables.
- * `count' has multiple roles, depending on its value.  If it is positive
- * or zero, there are no waiters.  The functions here will never be
- * called; see <asm/semaphore.h>
- *
- * When count is -1 it indicates there is at least one task waiting
- * for the semaphore.
- *
- * When count is less than that, there are '- count - 1' wakeups
- * pending.  ie if it has value -3, there are 2 wakeups pending.
- *
- * Note that these functions are only called when there is contention
- * on the lock, and as such all this is the "non-critical" part of the
- * whole semaphore business. The critical part is the inline stuff in
- * <asm/semaphore.h> where we want to avoid any extra jumps and calls.
- */
-void __up(struct semaphore *sem)
-{
-	sem->count--;
-	wake_up(&sem->wait);
-}
-
-#define wakers(count) (-1 - count)
-
-#define DOWN_HEAD							\
-	int ret = 0;							\
-	DECLARE_WAITQUEUE(wait, current);				\
-									\
-	/* Note that someone is waiting */				\
-	if (sem->count == 0)						\
-		sem->count = -1;					\
-									\
-	/* protected by the sentry still -- use unlocked version */	\
-	wait.flags = WQ_FLAG_EXCLUSIVE;					\
-	__add_wait_queue_tail(&sem->wait, &wait);			\
- lost_race:								\
-	spin_unlock_irq(&sem->sentry);					\
-
-#define DOWN_TAIL							\
-	spin_lock_irq(&sem->sentry);					\
-	if (wakers(sem->count) == 0 && ret == 0)			\
-		goto lost_race;	/* Someone stole our wakeup */		\
-	__remove_wait_queue(&sem->wait, &wait);				\
-	current->state = TASK_RUNNING;					\
-	if (!waitqueue_active(&sem->wait) && (sem->count < 0))		\
-		sem->count = wakers(sem->count);
-
-#define UPDATE_COUNT							\
-	sem->count += (sem->count < 0) ? 1 : - 1;
-	
-
-void __sched __down(struct semaphore * sem)
-{
-	DOWN_HEAD
-
-	for(;;) {
-		set_task_state(current, TASK_UNINTERRUPTIBLE);
-		/* we can _read_ this without the sentry */
-		if (sem->count != -1)
-			break;
- 		schedule();
- 	}
-
-	DOWN_TAIL
-	UPDATE_COUNT
-}
-
-int __sched __down_interruptible(struct semaphore * sem)
-{
-	DOWN_HEAD
-
-	for(;;) {
-		set_task_state(current, TASK_INTERRUPTIBLE);
-		/* we can _read_ this without the sentry */
-		if (sem->count != -1)
-			break;
-
-		if (signal_pending(current)) {
-			ret = -EINTR;
-			break;
-		}
-		schedule();
-	}
-
-	DOWN_TAIL
-
-	if (!ret) {
-		UPDATE_COUNT
-	}
-
-	return ret;
-}
-- 
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