2005-04-16 16:20:36 -06:00
|
|
|
#ifndef _I386_SEMAPHORE_H
|
|
|
|
#define _I386_SEMAPHORE_H
|
|
|
|
|
|
|
|
#include <linux/linkage.h>
|
|
|
|
|
|
|
|
#ifdef __KERNEL__
|
|
|
|
|
|
|
|
/*
|
|
|
|
* SMP- and interrupt-safe semaphores..
|
|
|
|
*
|
|
|
|
* (C) Copyright 1996 Linus Torvalds
|
|
|
|
*
|
|
|
|
* Modified 1996-12-23 by Dave Grothe <dave@gcom.com> to fix bugs in
|
|
|
|
* the original code and to make semaphore waits
|
|
|
|
* interruptible so that processes waiting on
|
|
|
|
* semaphores can be killed.
|
|
|
|
* Modified 1999-02-14 by Andrea Arcangeli, split the sched.c helper
|
|
|
|
* functions in asm/sempahore-helper.h while fixing a
|
|
|
|
* potential and subtle race discovered by Ulrich Schmid
|
|
|
|
* in down_interruptible(). Since I started to play here I
|
|
|
|
* also implemented the `trylock' semaphore operation.
|
|
|
|
* 1999-07-02 Artur Skawina <skawina@geocities.com>
|
|
|
|
* Optimized "0(ecx)" -> "(ecx)" (the assembler does not
|
|
|
|
* do this). Changed calling sequences from push/jmp to
|
|
|
|
* traditional call/ret.
|
|
|
|
* Modified 2001-01-01 Andreas Franck <afranck@gmx.de>
|
|
|
|
* Some hacks to ensure compatibility with recent
|
|
|
|
* GCC snapshots, to avoid stack corruption when compiling
|
|
|
|
* with -fomit-frame-pointer. It's not sure if this will
|
|
|
|
* be fixed in GCC, as our previous implementation was a
|
|
|
|
* bit dubious.
|
|
|
|
*
|
|
|
|
* If you would like to see an analysis of this implementation, please
|
|
|
|
* ftp to gcom.com and download the file
|
|
|
|
* /pub/linux/src/semaphore/semaphore-2.0.24.tar.gz.
|
|
|
|
*
|
|
|
|
*/
|
|
|
|
|
|
|
|
#include <asm/system.h>
|
|
|
|
#include <asm/atomic.h>
|
|
|
|
#include <linux/wait.h>
|
|
|
|
#include <linux/rwsem.h>
|
|
|
|
|
|
|
|
struct semaphore {
|
|
|
|
atomic_t count;
|
|
|
|
int sleepers;
|
|
|
|
wait_queue_head_t wait;
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
#define __SEMAPHORE_INITIALIZER(name, n) \
|
|
|
|
{ \
|
|
|
|
.count = ATOMIC_INIT(n), \
|
|
|
|
.sleepers = 0, \
|
|
|
|
.wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
|
|
|
|
}
|
|
|
|
|
|
|
|
#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)
|
|
|
|
{
|
|
|
|
/*
|
|
|
|
* *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
|
|
|
|
*
|
|
|
|
* i'd rather use the more flexible initialization above, but sadly
|
|
|
|
* GCC 2.7.2.3 emits a bogus warning. EGCS doesn't. Oh well.
|
|
|
|
*/
|
|
|
|
atomic_set(&sem->count, val);
|
|
|
|
sem->sleepers = 0;
|
|
|
|
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);
|
|
|
|
}
|
|
|
|
|
|
|
|
fastcall void __down_failed(void /* special register calling convention */);
|
|
|
|
fastcall int __down_failed_interruptible(void /* params in registers */);
|
|
|
|
fastcall int __down_failed_trylock(void /* params in registers */);
|
|
|
|
fastcall void __up_wakeup(void /* special register calling convention */);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* This is ugly, but we want the default case to fall through.
|
|
|
|
* "__down_failed" is a special asm handler that calls the C
|
|
|
|
* routine that actually waits. See arch/i386/kernel/semaphore.c
|
|
|
|
*/
|
|
|
|
static inline void down(struct semaphore * sem)
|
|
|
|
{
|
|
|
|
might_sleep();
|
|
|
|
__asm__ __volatile__(
|
|
|
|
"# atomic down operation\n\t"
|
2006-03-23 03:59:32 -07:00
|
|
|
LOCK_PREFIX "decl %0\n\t" /* --sem->count */
|
2006-09-26 02:52:32 -06:00
|
|
|
"jns 2f\n"
|
|
|
|
"\tlea %0,%%eax\n\t"
|
|
|
|
"call __down_failed\n"
|
|
|
|
"2:"
|
2006-07-08 16:24:18 -06:00
|
|
|
:"+m" (sem->count)
|
2005-04-16 16:20:36 -06:00
|
|
|
:
|
|
|
|
:"memory","ax");
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Interruptible try to acquire a semaphore. If we obtained
|
|
|
|
* it, return zero. If we were interrupted, returns -EINTR
|
|
|
|
*/
|
|
|
|
static inline int down_interruptible(struct semaphore * sem)
|
|
|
|
{
|
|
|
|
int result;
|
|
|
|
|
|
|
|
might_sleep();
|
|
|
|
__asm__ __volatile__(
|
|
|
|
"# atomic interruptible down operation\n\t"
|
2006-09-26 02:52:32 -06:00
|
|
|
"xorl %0,%0\n\t"
|
2006-03-23 03:59:32 -07:00
|
|
|
LOCK_PREFIX "decl %1\n\t" /* --sem->count */
|
2006-09-26 02:52:32 -06:00
|
|
|
"jns 2f\n\t"
|
|
|
|
"lea %1,%%eax\n\t"
|
|
|
|
"call __down_failed_interruptible\n"
|
|
|
|
"2:"
|
2006-07-08 16:24:18 -06:00
|
|
|
:"=a" (result), "+m" (sem->count)
|
2005-04-16 16:20:36 -06:00
|
|
|
:
|
|
|
|
:"memory");
|
|
|
|
return result;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Non-blockingly attempt to down() a semaphore.
|
|
|
|
* Returns zero if we acquired it
|
|
|
|
*/
|
|
|
|
static inline int down_trylock(struct semaphore * sem)
|
|
|
|
{
|
|
|
|
int result;
|
|
|
|
|
|
|
|
__asm__ __volatile__(
|
|
|
|
"# atomic interruptible down operation\n\t"
|
2006-09-26 02:52:32 -06:00
|
|
|
"xorl %0,%0\n\t"
|
2006-03-23 03:59:32 -07:00
|
|
|
LOCK_PREFIX "decl %1\n\t" /* --sem->count */
|
2006-09-26 02:52:32 -06:00
|
|
|
"jns 2f\n\t"
|
|
|
|
"lea %1,%%eax\n\t"
|
2005-04-16 16:20:36 -06:00
|
|
|
"call __down_failed_trylock\n\t"
|
2006-09-26 02:52:32 -06:00
|
|
|
"2:\n"
|
2006-07-08 16:24:18 -06:00
|
|
|
:"=a" (result), "+m" (sem->count)
|
2005-04-16 16:20:36 -06:00
|
|
|
:
|
|
|
|
:"memory");
|
|
|
|
return result;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Note! This is subtle. We jump to wake people up only if
|
|
|
|
* the semaphore was negative (== somebody was waiting on it).
|
|
|
|
*/
|
|
|
|
static inline void up(struct semaphore * sem)
|
|
|
|
{
|
|
|
|
__asm__ __volatile__(
|
|
|
|
"# atomic up operation\n\t"
|
2006-03-23 03:59:32 -07:00
|
|
|
LOCK_PREFIX "incl %0\n\t" /* ++sem->count */
|
2006-09-26 02:52:32 -06:00
|
|
|
"jg 1f\n\t"
|
|
|
|
"lea %0,%%eax\n\t"
|
|
|
|
"call __up_wakeup\n"
|
|
|
|
"1:"
|
2006-07-08 16:24:18 -06:00
|
|
|
:"+m" (sem->count)
|
2005-04-16 16:20:36 -06:00
|
|
|
:
|
|
|
|
:"memory","ax");
|
|
|
|
}
|
|
|
|
|
|
|
|
#endif
|
|
|
|
#endif
|