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Generic semaphore implementation

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Semaphores are no longer performance-critical, so a generic C
implementation is better for maintainability, debuggability and
extensibility.  Thanks to Peter Zijlstra for fixing the lockdep
warning.  Thanks to Harvey Harrison for pointing out that the
unlikely() was unnecessary.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Matthew Wilcox
2008-03-07 21:55:58 -05:00
committed by Matthew Wilcox
parent e48b3deee4
commit 64ac24e738
113 changed files with 314 additions and 7679 deletions
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193
include/asm-sparc/semaphore.h
View File

@@ -1,192 +1 @@
#ifndef _SPARC_SEMAPHORE_H
#define _SPARC_SEMAPHORE_H
/* Dinky, good for nothing, just barely irq safe, Sparc semaphores. */
#ifdef __KERNEL__
#include <asm/atomic.h>
#include <linux/wait.h>
#include <linux/rwsem.h>
struct semaphore {
atomic24_t count;
int sleepers;
wait_queue_head_t wait;
};
#define __SEMAPHORE_INITIALIZER(name, n) \
{ \
.count = ATOMIC24_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)
static inline void sema_init (struct semaphore *sem, int val)
{
atomic24_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);
}
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);
static inline void down(struct semaphore * sem)
{
register volatile int *ptr asm("g1");
register int increment asm("g2");
might_sleep();
ptr = &(sem->count.counter);
increment = 1;
__asm__ __volatile__(
"mov %%o7, %%g4\n\t"
"call ___atomic24_sub\n\t"
" add %%o7, 8, %%o7\n\t"
"tst %%g2\n\t"
"bl 2f\n\t"
" nop\n"
"1:\n\t"
".subsection 2\n"
"2:\n\t"
"save %%sp, -64, %%sp\n\t"
"mov %%g1, %%l1\n\t"
"mov %%g5, %%l5\n\t"
"call %3\n\t"
" mov %%g1, %%o0\n\t"
"mov %%l1, %%g1\n\t"
"ba 1b\n\t"
" restore %%l5, %%g0, %%g5\n\t"
".previous\n"
: "=&r" (increment)
: "0" (increment), "r" (ptr), "i" (__down)
: "g3", "g4", "g7", "memory", "cc");
}
static inline int down_interruptible(struct semaphore * sem)
{
register volatile int *ptr asm("g1");
register int increment asm("g2");
might_sleep();
ptr = &(sem->count.counter);
increment = 1;
__asm__ __volatile__(
"mov %%o7, %%g4\n\t"
"call ___atomic24_sub\n\t"
" add %%o7, 8, %%o7\n\t"
"tst %%g2\n\t"
"bl 2f\n\t"
" clr %%g2\n"
"1:\n\t"
".subsection 2\n"
"2:\n\t"
"save %%sp, -64, %%sp\n\t"
"mov %%g1, %%l1\n\t"
"mov %%g5, %%l5\n\t"
"call %3\n\t"
" mov %%g1, %%o0\n\t"
"mov %%l1, %%g1\n\t"
"mov %%l5, %%g5\n\t"
"ba 1b\n\t"
" restore %%o0, %%g0, %%g2\n\t"
".previous\n"
: "=&r" (increment)
: "0" (increment), "r" (ptr), "i" (__down_interruptible)
: "g3", "g4", "g7", "memory", "cc");
return increment;
}
static inline int down_trylock(struct semaphore * sem)
{
register volatile int *ptr asm("g1");
register int increment asm("g2");
ptr = &(sem->count.counter);
increment = 1;
__asm__ __volatile__(
"mov %%o7, %%g4\n\t"
"call ___atomic24_sub\n\t"
" add %%o7, 8, %%o7\n\t"
"tst %%g2\n\t"
"bl 2f\n\t"
" clr %%g2\n"
"1:\n\t"
".subsection 2\n"
"2:\n\t"
"save %%sp, -64, %%sp\n\t"
"mov %%g1, %%l1\n\t"
"mov %%g5, %%l5\n\t"
"call %3\n\t"
" mov %%g1, %%o0\n\t"
"mov %%l1, %%g1\n\t"
"mov %%l5, %%g5\n\t"
"ba 1b\n\t"
" restore %%o0, %%g0, %%g2\n\t"
".previous\n"
: "=&r" (increment)
: "0" (increment), "r" (ptr), "i" (__down_trylock)
: "g3", "g4", "g7", "memory", "cc");
return increment;
}
static inline void up(struct semaphore * sem)
{
register volatile int *ptr asm("g1");
register int increment asm("g2");
ptr = &(sem->count.counter);
increment = 1;
__asm__ __volatile__(
"mov %%o7, %%g4\n\t"
"call ___atomic24_add\n\t"
" add %%o7, 8, %%o7\n\t"
"tst %%g2\n\t"
"ble 2f\n\t"
" nop\n"
"1:\n\t"
".subsection 2\n"
"2:\n\t"
"save %%sp, -64, %%sp\n\t"
"mov %%g1, %%l1\n\t"
"mov %%g5, %%l5\n\t"
"call %3\n\t"
" mov %%g1, %%o0\n\t"
"mov %%l1, %%g1\n\t"
"ba 1b\n\t"
" restore %%l5, %%g0, %%g5\n\t"
".previous\n"
: "=&r" (increment)
: "0" (increment), "r" (ptr), "i" (__up)
: "g3", "g4", "g7", "memory", "cc");
}
#endif /* __KERNEL__ */
#endif /* !(_SPARC_SEMAPHORE_H) */
#include <linux/semaphore.h>