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>

3 files changed, 1 insertions, 108 deletions

diff --git a/arch/parisc/kernel/Makefile b/arch/parisc/kernel/Makefile
index 27827bc3717e..1f6585a56f97 100644
--- a/arch/parisc/kernel/Makefile
+++ b/arch/parisc/kernel/Makefile
@@ -9,7 +9,7 @@ AFLAGS_pacache.o := -traditional
 
 obj-y	     	:= cache.o pacache.o setup.o traps.o time.o irq.o \
 		   pa7300lc.o syscall.o entry.o sys_parisc.o firmware.o \
-		   ptrace.o hardware.o inventory.o drivers.o semaphore.o \
+		   ptrace.o hardware.o inventory.o drivers.o \
 		   signal.o hpmc.o real2.o parisc_ksyms.o unaligned.o \
 		   process.o processor.o pdc_cons.o pdc_chassis.o unwind.o \
 		   topology.o
diff --git a/arch/parisc/kernel/parisc_ksyms.c b/arch/parisc/kernel/parisc_ksyms.c
index 7aca704e96f0..5b7fc4aa044d 100644
--- a/arch/parisc/kernel/parisc_ksyms.c
+++ b/arch/parisc/kernel/parisc_ksyms.c
@@ -69,11 +69,6 @@ EXPORT_SYMBOL(memcpy_toio);
 EXPORT_SYMBOL(memcpy_fromio);
 EXPORT_SYMBOL(memset_io);
 
-#include <asm/semaphore.h>
-EXPORT_SYMBOL(__up);
-EXPORT_SYMBOL(__down_interruptible);
-EXPORT_SYMBOL(__down);
-
 extern void $$divI(void);
 extern void $$divU(void);
 extern void $$remI(void);
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;
-}