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>

1 files changed, 1 insertions, 144 deletions

diff --git a/include/asm-m32r/semaphore.h b/include/asm-m32r/semaphore.h
index b5bf95a6f2b4..d9b2034ed1d2 100644
--- a/include/asm-m32r/semaphore.h
+++ b/include/asm-m32r/semaphore.h
@@ -1,144 +1 @@
-#ifndef _ASM_M32R_SEMAPHORE_H
-#define _ASM_M32R_SEMAPHORE_H
-
-#include <linux/linkage.h>
-
-#ifdef __KERNEL__
-
-/*
- * SMP- and interrupt-safe semaphores..
- *
- * Copyright (C) 1996  Linus Torvalds
- * Copyright (C) 2004, 2006  Hirokazu Takata <takata at linux-m32r.org>
- */
-
-#include <linux/wait.h>
-#include <linux/rwsem.h>
-#include <asm/assembler.h>
-#include <asm/system.h>
-#include <asm/atomic.h>
-
-struct semaphore {
-        atomic_t count;
-        int sleepers;
-        wait_queue_head_t wait;
-};
-
-#define __SEMAPHORE_INITIALIZER(name, n)                                \
-{                                                                       \
-        .count          = ATOMIC_INIT(n),                               \
-        .sleepers       = 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);
- *
- * i'd rather use the more flexible initialization above, but sadly
- * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well.
- */
-        atomic_set(&sem->count, val);
-        sem->sleepers = 0;
-        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_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);
-
-/*
- * Atomically decrement the semaphore's count.  If it goes negative,
- * block the calling thread in the TASK_UNINTERRUPTIBLE state.
- */
-static inline void down(struct semaphore * sem)
-{
-        might_sleep();
-        if (unlikely(atomic_dec_return(&sem->count) < 0))
-                __down(sem);
-}
-
-/*
- * Interruptible try to acquire a semaphore.  If we obtained
- * it, return zero.  If we were interrupted, returns -EINTR
- */
-static inline int down_interruptible(struct semaphore * sem)
-{
-        int result = 0;
-
-        might_sleep();
-        if (unlikely(atomic_dec_return(&sem->count) < 0))
-                result = __down_interruptible(sem);
-
-        return result;
-}
-
-/*
- * Non-blockingly attempt to down() a semaphore.
- * Returns zero if we acquired it
- */
-static inline int down_trylock(struct semaphore * sem)
-{
-        unsigned long flags;
-        long count;
-        int result = 0;
-
-        local_irq_save(flags);
-        __asm__ __volatile__ (
-                "# down_trylock                 \n\t"
-                DCACHE_CLEAR("%0", "r4", "%1")
-                M32R_LOCK" %0, @%1;             \n\t"
-                "addi   %0, #-1;                \n\t"
-                M32R_UNLOCK" %0, @%1;           \n\t"
-                : "=&r" (count)
-                : "r" (&sem->count)
-                : "memory"
-#ifdef CONFIG_CHIP_M32700_TS1
-                , "r4"
-#endif  /* CONFIG_CHIP_M32700_TS1 */
-        );
-        local_irq_restore(flags);
-
-        if (unlikely(count < 0))
-                result = __down_trylock(sem);
-
-        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)
-{
-        if (unlikely(atomic_inc_return(&sem->count) <= 0))
-                __up(sem);
-}
-
-#endif  /* __KERNEL__ */
-
-#endif  /* _ASM_M32R_SEMAPHORE_H */
+#include <linux/semaphore.h>