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, 182 deletions

diff --git a/include/asm-arm/semaphore-helper.h b/include/asm-arm/semaphore-helper.h
deleted file mode 100644
index 1d7f1987edb9..000000000000
--- a/include/asm-arm/semaphore-helper.h
+++ /dev/null
@@ -1,84 +0,0 @@
-#ifndef ASMARM_SEMAPHORE_HELPER_H
-#define ASMARM_SEMAPHORE_HELPER_H
-
-/*
- * These two _must_ execute atomically wrt each other.
- */
-static inline void wake_one_more(struct semaphore * sem)
-{
-        unsigned long flags;
-
-        spin_lock_irqsave(&semaphore_wake_lock, flags);
-        if (atomic_read(&sem->count) <= 0)
-                sem->waking++;
-        spin_unlock_irqrestore(&semaphore_wake_lock, flags);
-}
-
-static inline int waking_non_zero(struct semaphore *sem)
-{
-        unsigned long flags;
-        int ret = 0;
-
-        spin_lock_irqsave(&semaphore_wake_lock, flags);
-        if (sem->waking > 0) {
-                sem->waking--;
-                ret = 1;
-        }
-        spin_unlock_irqrestore(&semaphore_wake_lock, flags);
-        return ret;
-}
-
-/*
- * waking non zero interruptible
- *      1       got the lock
- *      0       go to sleep
- *      -EINTR  interrupted
- *
- * We must undo the sem->count down_interruptible() increment while we are
- * protected by the spinlock in order to make this atomic_inc() with the
- * atomic_read() in wake_one_more(), otherwise we can race. -arca
- */
-static inline int waking_non_zero_interruptible(struct semaphore *sem,
-                                                struct task_struct *tsk)
-{
-        unsigned long flags;
-        int ret = 0;
-
-        spin_lock_irqsave(&semaphore_wake_lock, flags);
-        if (sem->waking > 0) {
-                sem->waking--;
-                ret = 1;
-        } else if (signal_pending(tsk)) {
-                atomic_inc(&sem->count);
-                ret = -EINTR;
-        }
-        spin_unlock_irqrestore(&semaphore_wake_lock, flags);
-        return ret;     
-}
-
-/*
- * waking_non_zero_try_lock:
- *      1       failed to lock
- *      0       got the lock
- *
- * We must undo the sem->count down_interruptible() increment while we are
- * protected by the spinlock in order to make this atomic_inc() with the
- * atomic_read() in wake_one_more(), otherwise we can race. -arca
- */
-static inline int waking_non_zero_trylock(struct semaphore *sem)
-{
-        unsigned long flags;
-        int ret = 1;
-
-        spin_lock_irqsave(&semaphore_wake_lock, flags);
-        if (sem->waking <= 0)
-                atomic_inc(&sem->count);
-        else {
-                sem->waking--;
-                ret = 0;
-        }
-        spin_unlock_irqrestore(&semaphore_wake_lock, flags);
-        return ret;
-}
-
-#endif
diff --git a/include/asm-arm/semaphore.h b/include/asm-arm/semaphore.h
index 1c8b441f89e3..d9b2034ed1d2 100644
--- a/include/asm-arm/semaphore.h
+++ b/include/asm-arm/semaphore.h
@@ -1,98 +1 @@
-/*
- * linux/include/asm-arm/semaphore.h
- */
-#ifndef __ASM_ARM_SEMAPHORE_H
-#define __ASM_ARM_SEMAPHORE_H
-
-#include <linux/linkage.h>
-#include <linux/spinlock.h>
-#include <linux/wait.h>
-#include <linux/rwsem.h>
-
-#include <asm/atomic.h>
-#include <asm/locks.h>
-
-struct semaphore {
-        atomic_t count;
-        int sleepers;
-        wait_queue_head_t wait;
-};
-
-#define __SEMAPHORE_INIT(name, cnt)                             \
-{                                                               \
-        .count  = ATOMIC_INIT(cnt),                             \
-        .wait   = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait),   \
-}
-
-#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
-        struct semaphore name = __SEMAPHORE_INIT(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);
-        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);
-}
-
-/*
- * special register calling convention
- */
-asmlinkage void __down_failed(void);
-asmlinkage int  __down_interruptible_failed(void);
-asmlinkage int  __down_trylock_failed(void);
-asmlinkage void __up_wakeup(void);
-
-extern void __down(struct semaphore * sem);
-extern int  __down_interruptible(struct semaphore * sem);
-extern int  __down_trylock(struct semaphore * sem);
-extern void __up(struct semaphore * sem);
-
-/*
- * This is ugly, but we want the default case to fall through.
- * "__down" is the actual routine that waits...
- */
-static inline void down(struct semaphore * sem)
-{
-        might_sleep();
-        __down_op(sem, __down_failed);
-}
-
-/*
- * This is ugly, but we want the default case to fall through.
- * "__down_interruptible" is the actual routine that waits...
- */
-static inline int down_interruptible (struct semaphore * sem)
-{
-        might_sleep();
-        return __down_op_ret(sem, __down_interruptible_failed);
-}
-
-static inline int down_trylock(struct semaphore *sem)
-{
-        return __down_op_ret(sem, __down_trylock_failed);
-}
-
-/*
- * 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)
-{
-        __up_op(sem, __up_wakeup);
-}
-
-#endif
+#include <linux/semaphore.h>