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#ifndef _SPL_MUTEX_H
#define _SPL_MUTEX_H
#ifdef __cplusplus
extern "C" {
#endif
#include <linux/module.h>
#include <sys/types.h>
/* See the "Big Theory Statement" in solaris mutex.c.
*
* Spin mutexes apparently aren't needed by zfs so we assert
* if ibc is non-zero.
*
* Our impementation of adaptive mutexes aren't really adaptive.
* They go to sleep every time.
*/
#define MUTEX_DEFAULT 0
#define MUTEX_HELD(x) (mutex_owned(x))
#define KM_MAGIC 0x42424242
#define KM_POISON 0x84
typedef struct {
int km_magic;
char *km_name;
struct task_struct *km_owner;
struct semaphore km_sem;
} kmutex_t;
#undef mutex_init
static __inline__ void
mutex_init(kmutex_t *mp, char *name, int type, void *ibc)
{
BUG_ON(ibc != NULL); /* XXX - Spin mutexes not needed? */
BUG_ON(type != MUTEX_DEFAULT); /* XXX - Only default type supported? */
mp->km_magic = KM_MAGIC;
sema_init(&mp->km_sem, 1);
mp->km_owner = NULL;
mp->km_name = NULL;
if (name) {
mp->km_name = kmalloc(strlen(name) + 1, GFP_KERNEL);
if (mp->km_name)
strcpy(mp->km_name, name);
}
}
#undef mutex_destroy
static __inline__ void
mutex_destroy(kmutex_t *mp)
{
BUG_ON(mp->km_magic != KM_MAGIC);
if (mp->km_name)
kfree(mp->km_name);
memset(mp, KM_POISON, sizeof(*mp));
}
static __inline__ void
mutex_enter(kmutex_t *mp)
{
BUG_ON(mp->km_magic != KM_MAGIC);
down(&mp->km_sem); /* Will check in_atomic() for us */
BUG_ON(mp->km_owner != NULL);
mp->km_owner = current;
}
/* Return 1 if we acquired the mutex, else zero.
*/
static __inline__ int
mutex_tryenter(kmutex_t *mp)
{
int result;
BUG_ON(mp->km_magic != KM_MAGIC);
result = down_trylock(&mp->km_sem); /* returns 0 if acquired */
if (result == 0) {
BUG_ON(mp->km_owner != NULL);
mp->km_owner = current;
return 1;
}
return 0;
}
static __inline__ void
mutex_exit(kmutex_t *mp)
{
BUG_ON(mp->km_magic != KM_MAGIC);
BUG_ON(mp->km_owner != current);
mp->km_owner = NULL;
up(&mp->km_sem);
}
/* Return 1 if mutex is held by current process, else zero.
*/
static __inline__ int
mutex_owned(kmutex_t *mp)
{
BUG_ON(mp->km_magic != KM_MAGIC);
return (mp->km_owner == current);
}
/* Return owner if mutex is owned, else NULL.
*/
static __inline__ kthread_t *
mutex_owner(kmutex_t *mp)
{
BUG_ON(mp->km_magic != KM_MAGIC);
return mp->km_owner;
}
#ifdef __cplusplus
}
#endif
#endif /* _SPL_MUTEX_H */
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