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include/asm-parisc/semaphore-helper.h
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1da177e4c Linux-2.6.12-rc2 |
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#ifndef _ASM_PARISC_SEMAPHORE_HELPER_H #define _ASM_PARISC_SEMAPHORE_HELPER_H /* * SMP- and interrupt-safe semaphores helper functions. * * (C) Copyright 1996 Linus Torvalds * (C) Copyright 1999 Andrea Arcangeli */ /* * These two _must_ execute atomically wrt each other. * * This is trivially done with load_locked/store_cond, * which we have. Let the rest of the losers suck eggs. */ static __inline__ void wake_one_more(struct semaphore * sem) { atomic_inc((atomic_t *)&sem->waking); } 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 atomic 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_trylock: * 1 failed to lock * 0 got the lock * * We must undo the sem->count down_trylock() increment while we are * protected by the spinlock in order to make atomic 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 /* _ASM_PARISC_SEMAPHORE_HELPER_H */ |