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