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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-cris/semaphore.h | |
download | linux-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-cris/semaphore.h')
-rw-r--r-- | include/asm-cris/semaphore.h | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/include/asm-cris/semaphore.h b/include/asm-cris/semaphore.h new file mode 100644 index 000000000000..605aa7eaaaf8 --- /dev/null +++ b/include/asm-cris/semaphore.h @@ -0,0 +1,142 @@ +/* $Id: semaphore.h,v 1.3 2001/05/08 13:54:09 bjornw Exp $ */ + +/* On the i386 these are coded in asm, perhaps we should as well. Later.. */ + +#ifndef _CRIS_SEMAPHORE_H +#define _CRIS_SEMAPHORE_H + +#define RW_LOCK_BIAS 0x01000000 + +#include <linux/wait.h> +#include <linux/spinlock.h> +#include <linux/rwsem.h> + +#include <asm/system.h> +#include <asm/atomic.h> + +/* + * CRIS semaphores, implemented in C-only so far. + */ + +int printk(const char *fmt, ...); + +struct semaphore { + atomic_t count; + atomic_t waking; + wait_queue_head_t wait; +}; + +#define __SEMAPHORE_INITIALIZER(name, n) \ +{ \ + .count = ATOMIC_INIT(n), \ + .waking = ATOMIC_INIT(0), \ + .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) + +extern inline void sema_init(struct semaphore *sem, int val) +{ + *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); +} + +extern inline void init_MUTEX (struct semaphore *sem) +{ + sema_init(sem, 1); +} + +extern 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 int __down_trylock(struct semaphore * sem); +extern void __up(struct semaphore * sem); + +/* notice - we probably can do cli/sti here instead of saving */ + +extern inline void down(struct semaphore * sem) +{ + unsigned long flags; + int failed; + + might_sleep(); + + /* atomically decrement the semaphores count, and if its negative, we wait */ + local_save_flags(flags); + local_irq_disable(); + failed = --(sem->count.counter) < 0; + local_irq_restore(flags); + if(failed) { + __down(sem); + } +} + +/* + * This version waits in interruptible state so that the waiting + * process can be killed. The down_interruptible routine + * returns negative for signalled and zero for semaphore acquired. + */ + +extern inline int down_interruptible(struct semaphore * sem) +{ + unsigned long flags; + int failed; + + might_sleep(); + + /* atomically decrement the semaphores count, and if its negative, we wait */ + local_save_flags(flags); + local_irq_disable(); + failed = --(sem->count.counter) < 0; + local_irq_restore(flags); + if(failed) + failed = __down_interruptible(sem); + return(failed); +} + +extern inline int down_trylock(struct semaphore * sem) +{ + unsigned long flags; + int failed; + + local_save_flags(flags); + local_irq_disable(); + failed = --(sem->count.counter) < 0; + local_irq_restore(flags); + if(failed) + failed = __down_trylock(sem); + return(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(). + */ +extern inline void up(struct semaphore * sem) +{ + unsigned long flags; + int wakeup; + + /* atomically increment the semaphores count, and if it was negative, we wake people */ + local_save_flags(flags); + local_irq_disable(); + wakeup = ++(sem->count.counter) <= 0; + local_irq_restore(flags); + if(wakeup) { + __up(sem); + } +} + +#endif |