diff options
author | Matthew Wilcox <matthew@wil.cx> | 2008-03-07 21:55:58 -0500 |
---|---|---|
committer | Matthew Wilcox <willy@linux.intel.com> | 2008-04-17 10:42:34 -0400 |
commit | 64ac24e738823161693bf791f87adc802cf529ff (patch) | |
tree | 19c0b0cf314d4394ca580c05b86cdf874ce0a167 /include/asm-arm | |
parent | e48b3deee475134585eed03e7afebe4bf9e0dba9 (diff) | |
download | kernel_samsung_smdk4412-64ac24e738823161693bf791f87adc802cf529ff.zip kernel_samsung_smdk4412-64ac24e738823161693bf791f87adc802cf529ff.tar.gz kernel_samsung_smdk4412-64ac24e738823161693bf791f87adc802cf529ff.tar.bz2 |
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>
Diffstat (limited to 'include/asm-arm')
-rw-r--r-- | include/asm-arm/semaphore-helper.h | 84 | ||||
-rw-r--r-- | include/asm-arm/semaphore.h | 99 |
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 1d7f198..0000000 --- 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 1c8b441..d9b2034 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> |