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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 00:20:36 +0200 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 00:20:36 +0200 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-mips/semaphore.h | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip |
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-mips/semaphore.h')
-rw-r--r-- | include/asm-mips/semaphore.h | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/include/asm-mips/semaphore.h b/include/asm-mips/semaphore.h new file mode 100644 index 000000000000..c2c97dec661b --- /dev/null +++ b/include/asm-mips/semaphore.h @@ -0,0 +1,112 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 1996 Linus Torvalds + * Copyright (C) 1998, 99, 2000, 01, 04 Ralf Baechle + * Copyright (C) 1999, 2000, 01 Silicon Graphics, Inc. + * Copyright (C) 2000, 01 MIPS Technologies, Inc. + * + * In all honesty, little of the old MIPS code left - the PPC64 variant was + * just looking nice and portable so I ripped it. Credits to whoever wrote + * it. + */ +#ifndef __ASM_SEMAPHORE_H +#define __ASM_SEMAPHORE_H + +/* + * Remove spinlock-based RW semaphores; RW semaphore definitions are + * now in rwsem.h and we use the generic lib/rwsem.c implementation. + * Rework semaphores to use atomic_dec_if_positive. + * -- Paul Mackerras (paulus@samba.org) + */ + +#ifdef __KERNEL__ + +#include <asm/atomic.h> +#include <asm/system.h> +#include <linux/wait.h> +#include <linux/rwsem.h> + +struct semaphore { + /* + * Note that any negative value of count is equivalent to 0, + * but additionally indicates that some process(es) might be + * sleeping on `wait'. + */ + 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) +{ + 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 * sem); +extern int __down_interruptible(struct semaphore * sem); +extern void __up(struct semaphore * sem); + +static inline void down(struct semaphore * sem) +{ + might_sleep(); + + /* + * Try to get the semaphore, take the slow path if we fail. + */ + if (unlikely(atomic_dec_return(&sem->count) < 0)) + __down(sem); +} + +static inline int down_interruptible(struct semaphore * sem) +{ + int ret = 0; + + might_sleep(); + + if (unlikely(atomic_dec_return(&sem->count) < 0)) + ret = __down_interruptible(sem); + return ret; +} + +static inline int down_trylock(struct semaphore * sem) +{ + return atomic_dec_if_positive(&sem->count) < 0; +} + +static inline void up(struct semaphore * sem) +{ + if (unlikely(atomic_inc_return(&sem->count) <= 0)) + __up(sem); +} + +#endif /* __KERNEL__ */ + +#endif /* __ASM_SEMAPHORE_H */ |