diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-alpha/semaphore.h |
Linux-2.6.12-rc2v2.6.12-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-alpha/semaphore.h')
-rw-r--r-- | include/asm-alpha/semaphore.h | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/include/asm-alpha/semaphore.h b/include/asm-alpha/semaphore.h new file mode 100644 index 00000000000..eb2cbd97d40 --- /dev/null +++ b/include/asm-alpha/semaphore.h @@ -0,0 +1,153 @@ +#ifndef _ALPHA_SEMAPHORE_H +#define _ALPHA_SEMAPHORE_H + +/* + * SMP- and interrupt-safe semaphores.. + * + * (C) Copyright 1996 Linus Torvalds + * (C) Copyright 1996, 2000 Richard Henderson + */ + +#include <asm/current.h> +#include <asm/system.h> +#include <asm/atomic.h> +#include <linux/compiler.h> +#include <linux/wait.h> +#include <linux/rwsem.h> + +struct semaphore { + atomic_t count; + wait_queue_head_t wait; +}; + +#define __SEMAPHORE_INITIALIZER(name, n) \ +{ \ + .count = ATOMIC_INIT(n), \ + .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait), \ +} + +#define __MUTEX_INITIALIZER(name) \ + __SEMAPHORE_INITIALIZER(name,1) + +#define __DECLARE_SEMAPHORE_GENERIC(name,count) \ + struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) + +#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) +#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) + +static inline void sema_init(struct semaphore *sem, int val) +{ + /* + * Logically, + * *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); + * except that gcc produces better initializing by parts yet. + */ + + atomic_set(&sem->count, val); + 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); +} + +extern void down(struct semaphore *); +extern void __down_failed(struct semaphore *); +extern int down_interruptible(struct semaphore *); +extern int __down_failed_interruptible(struct semaphore *); +extern int down_trylock(struct semaphore *); +extern void up(struct semaphore *); +extern void __up_wakeup(struct semaphore *); + +/* + * Hidden out of line code is fun, but extremely messy. Rely on newer + * compilers to do a respectable job with this. The contention cases + * are handled out of line in arch/alpha/kernel/semaphore.c. + */ + +static inline void __down(struct semaphore *sem) +{ + long count; + might_sleep(); + count = atomic_dec_return(&sem->count); + if (unlikely(count < 0)) + __down_failed(sem); +} + +static inline int __down_interruptible(struct semaphore *sem) +{ + long count; + might_sleep(); + count = atomic_dec_return(&sem->count); + if (unlikely(count < 0)) + return __down_failed_interruptible(sem); + return 0; +} + +/* + * down_trylock returns 0 on success, 1 if we failed to get the lock. + */ + +static inline int __down_trylock(struct semaphore *sem) +{ + long ret; + + /* "Equivalent" C: + + do { + ret = ldl_l; + --ret; + if (ret < 0) + break; + ret = stl_c = ret; + } while (ret == 0); + */ + __asm__ __volatile__( + "1: ldl_l %0,%1\n" + " subl %0,1,%0\n" + " blt %0,2f\n" + " stl_c %0,%1\n" + " beq %0,3f\n" + " mb\n" + "2:\n" + ".subsection 2\n" + "3: br 1b\n" + ".previous" + : "=&r" (ret), "=m" (sem->count) + : "m" (sem->count)); + + return ret < 0; +} + +static inline void __up(struct semaphore *sem) +{ + if (unlikely(atomic_inc_return(&sem->count) <= 0)) + __up_wakeup(sem); +} + +#if !defined(CONFIG_DEBUG_SEMAPHORE) +extern inline void down(struct semaphore *sem) +{ + __down(sem); +} +extern inline int down_interruptible(struct semaphore *sem) +{ + return __down_interruptible(sem); +} +extern inline int down_trylock(struct semaphore *sem) +{ + return __down_trylock(sem); +} +extern inline void up(struct semaphore *sem) +{ + __up(sem); +} +#endif + +#endif |