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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-sh/semaphore-helper.h | |
download | linux-fsl-qoriq-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'include/asm-sh/semaphore-helper.h')
-rw-r--r-- | include/asm-sh/semaphore-helper.h | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/include/asm-sh/semaphore-helper.h b/include/asm-sh/semaphore-helper.h new file mode 100644 index 0000000..bd8230c --- /dev/null +++ b/include/asm-sh/semaphore-helper.h @@ -0,0 +1,89 @@ +#ifndef __ASM_SH_SEMAPHORE_HELPER_H +#define __ASM_SH_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->sleepers); +} + +static __inline__ int waking_non_zero(struct semaphore *sem) +{ + unsigned long flags; + int ret = 0; + + spin_lock_irqsave(&semaphore_wake_lock, flags); + if (sem->sleepers > 0) { + sem->sleepers--; + 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->sleepers > 0) { + sem->sleepers--; + 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->sleepers <= 0) + atomic_inc(&sem->count); + else { + sem->sleepers--; + ret = 0; + } + spin_unlock_irqrestore(&semaphore_wake_lock, flags); + return ret; +} + +#endif /* __ASM_SH_SEMAPHORE_HELPER_H */ |