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>
diff --git a/include/asm-s390/semaphore.h b/include/asm-s390/semaphore.h
index 0e7001a..d9b2034 100644
--- a/include/asm-s390/semaphore.h
+++ b/include/asm-s390/semaphore.h
@@ -1,107 +1 @@
-/*
- * include/asm-s390/semaphore.h
- *
- * S390 version
- * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
- *
- * Derived from "include/asm-i386/semaphore.h"
- * (C) Copyright 1996 Linus Torvalds
- */
-
-#ifndef _S390_SEMAPHORE_H
-#define _S390_SEMAPHORE_H
-
-#include <asm/system.h>
-#include <asm/atomic.h>
-#include <linux/wait.h>
-#include <linux/rwsem.h>
-
-struct semaphore {
- /*
- * Note that any negative value of count is equivalent to 0,
- * but additionally indicates that some process(es) might be
- * sleeping on `wait'.
- */
- atomic_t count;
- wait_queue_head_t wait;
-};
-
-#define __SEMAPHORE_INITIALIZER(name,count) \
- { ATOMIC_INIT(count), __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)
-{
- atomic_set(&sem->count, val);
- init_waitqueue_head(&sem->wait);
-}
-
-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(struct semaphore * sem);
-asmlinkage int __down_interruptible(struct semaphore * sem);
-asmlinkage int __down_trylock(struct semaphore * sem);
-asmlinkage void __up(struct semaphore * sem);
-
-static inline void down(struct semaphore * sem)
-{
- might_sleep();
- if (atomic_dec_return(&sem->count) < 0)
- __down(sem);
-}
-
-static inline int down_interruptible(struct semaphore * sem)
-{
- int ret = 0;
-
- might_sleep();
- if (atomic_dec_return(&sem->count) < 0)
- ret = __down_interruptible(sem);
- return ret;
-}
-
-static inline int down_trylock(struct semaphore * sem)
-{
- int old_val, new_val;
-
- /*
- * This inline assembly atomically implements the equivalent
- * to the following C code:
- * old_val = sem->count.counter;
- * if ((new_val = old_val) > 0)
- * sem->count.counter = --new_val;
- * In the ppc code this is called atomic_dec_if_positive.
- */
- asm volatile(
- " l %0,0(%3)\n"
- "0: ltr %1,%0\n"
- " jle 1f\n"
- " ahi %1,-1\n"
- " cs %0,%1,0(%3)\n"
- " jl 0b\n"
- "1:"
- : "=&d" (old_val), "=&d" (new_val), "=m" (sem->count.counter)
- : "a" (&sem->count.counter), "m" (sem->count.counter)
- : "cc", "memory");
- return old_val <= 0;
-}
-
-static inline void up(struct semaphore * sem)
-{
- if (atomic_inc_return(&sem->count) <= 0)
- __up(sem);
-}
-
-#endif
+#include <linux/semaphore.h>