From 64ac24e738823161693bf791f87adc802cf529ff Mon Sep 17 00:00:00 2001 From: Matthew Wilcox 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 Acked-by: Ingo Molnar --- include/asm-m68knommu/semaphore-helper.h | 82 ---------------- include/asm-m68knommu/semaphore.h | 154 +------------------------------ 2 files changed, 1 insertion(+), 235 deletions(-) delete mode 100644 include/asm-m68knommu/semaphore-helper.h (limited to 'include/asm-m68knommu') diff --git a/include/asm-m68knommu/semaphore-helper.h b/include/asm-m68knommu/semaphore-helper.h deleted file mode 100644 index 43da7bc483c7..000000000000 --- a/include/asm-m68knommu/semaphore-helper.h +++ /dev/null @@ -1,82 +0,0 @@ -#ifndef _M68K_SEMAPHORE_HELPER_H -#define _M68K_SEMAPHORE_HELPER_H - -/* - * SMP- and interrupt-safe semaphores helper functions. - * - * (C) Copyright 1996 Linus Torvalds - * - * m68k version by Andreas Schwab - */ - - -/* - * These two _must_ execute atomically wrt each other. - */ -static inline void wake_one_more(struct semaphore * sem) -{ - atomic_inc(&sem->waking); -} - -static inline int waking_non_zero(struct semaphore *sem) -{ - int ret; - unsigned long flags; - - spin_lock_irqsave(&semaphore_wake_lock, flags); - ret = 0; - if (atomic_read(&sem->waking) > 0) { - atomic_dec(&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 - */ -static inline int waking_non_zero_interruptible(struct semaphore *sem, - struct task_struct *tsk) -{ - int ret; - unsigned long flags; - - spin_lock_irqsave(&semaphore_wake_lock, flags); - ret = 0; - if (atomic_read(&sem->waking) > 0) { - atomic_dec(&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_trylock: - * 1 failed to lock - * 0 got the lock - */ -static inline int waking_non_zero_trylock(struct semaphore *sem) -{ - int ret; - unsigned long flags; - - spin_lock_irqsave(&semaphore_wake_lock, flags); - ret = 1; - if (atomic_read(&sem->waking) > 0) { - atomic_dec(&sem->waking); - ret = 0; - } else - atomic_inc(&sem->count); - spin_unlock_irqrestore(&semaphore_wake_lock, flags); - return ret; -} - -#endif diff --git a/include/asm-m68knommu/semaphore.h b/include/asm-m68knommu/semaphore.h index 5779eb6c0689..d9b2034ed1d2 100644 --- a/include/asm-m68knommu/semaphore.h +++ b/include/asm-m68knommu/semaphore.h @@ -1,153 +1 @@ -#ifndef _M68K_SEMAPHORE_H -#define _M68K_SEMAPHORE_H - -#define RW_LOCK_BIAS 0x01000000 - -#ifndef __ASSEMBLY__ - -#include -#include -#include -#include - -#include -#include - -/* - * Interrupt-safe semaphores.. - * - * (C) Copyright 1996 Linus Torvalds - * - * m68k version by Andreas Schwab - */ - - -struct semaphore { - atomic_t count; - atomic_t waking; - wait_queue_head_t wait; -}; - -#define __SEMAPHORE_INITIALIZER(name, n) \ -{ \ - .count = ATOMIC_INIT(n), \ - .waking = ATOMIC_INIT(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); -} - -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); - -extern spinlock_t semaphore_wake_lock; - -/* - * This is ugly, but we want the default case to fall through. - * "down_failed" is a special asm handler that calls the C - * routine that actually waits. See arch/m68k/lib/semaphore.S - */ -static inline void down(struct semaphore * sem) -{ - might_sleep(); - __asm__ __volatile__( - "| atomic down operation\n\t" - "movel %0, %%a1\n\t" - "lea %%pc@(1f), %%a0\n\t" - "subql #1, %%a1@\n\t" - "jmi __down_failed\n" - "1:" - : /* no outputs */ - : "g" (sem) - : "cc", "%a0", "%a1", "memory"); -} - -static inline int down_interruptible(struct semaphore * sem) -{ - int ret; - - might_sleep(); - __asm__ __volatile__( - "| atomic down operation\n\t" - "movel %1, %%a1\n\t" - "lea %%pc@(1f), %%a0\n\t" - "subql #1, %%a1@\n\t" - "jmi __down_failed_interruptible\n\t" - "clrl %%d0\n" - "1: movel %%d0, %0\n" - : "=d" (ret) - : "g" (sem) - : "cc", "%d0", "%a0", "%a1", "memory"); - return(ret); -} - -static inline int down_trylock(struct semaphore * sem) -{ - register struct semaphore *sem1 __asm__ ("%a1") = sem; - register int result __asm__ ("%d0"); - - __asm__ __volatile__( - "| atomic down trylock operation\n\t" - "subql #1,%1@\n\t" - "jmi 2f\n\t" - "clrl %0\n" - "1:\n" - ".section .text.lock,\"ax\"\n" - ".even\n" - "2:\tpea 1b\n\t" - "jbra __down_failed_trylock\n" - ".previous" - : "=d" (result) - : "a" (sem1) - : "memory"); - 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) -{ - __asm__ __volatile__( - "| atomic up operation\n\t" - "movel %0, %%a1\n\t" - "lea %%pc@(1f), %%a0\n\t" - "addql #1, %%a1@\n\t" - "jle __up_wakeup\n" - "1:" - : /* no outputs */ - : "g" (sem) - : "cc", "%a0", "%a1", "memory"); -} - -#endif /* __ASSEMBLY__ */ - -#endif +#include -- cgit v1.2.3