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71cc2733a7
To be consistent. Mutexes are futex based but have own semantics so better to be able to distinguish the types. Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Acked-by: Andrey Vagin <avagin@parallels.com> Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
113 lines
2.4 KiB
C
113 lines
2.4 KiB
C
#ifndef CR_LOCK_H_
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#define CR_LOCK_H_
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#include <linux/futex.h>
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#include <sys/time.h>
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#include <limits.h>
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#include <errno.h>
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#include "types.h"
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#include "atomic.h"
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#include "syscall.h"
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#include "util.h"
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typedef struct {
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u32 raw;
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} futex_t;
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/* Get current futex @f value */
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static inline u32 futex_get(futex_t *f)
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{
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return atomic_get(&f->raw);
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}
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/* Set futex @f value to @v */
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static inline void futex_set(futex_t *f, u32 v)
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{
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atomic_set(&f->raw, v);
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}
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#define futex_init(f) futex_set(f, 0)
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/* Wait on futex @__f value @__v become in condition @__c */
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#define futex_wait_if_cond(__f, __v, __cond) \
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do { \
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int ret; \
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u32 tmp; \
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\
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while (1) { \
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tmp = (__f)->raw; \
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if (tmp __cond (__v)) \
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break; \
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ret = sys_futex(&(__f)->raw, FUTEX_WAIT,\
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tmp, NULL, NULL, 0); \
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BUG_ON(ret < 0 && ret != -EWOULDBLOCK); \
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} \
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} while (0)
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/* Set futex @f to @v and wake up all waiters */
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static inline void futex_set_and_wake(futex_t *f, u32 v)
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{
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atomic_set(&f->raw, v);
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BUG_ON(sys_futex(&f->raw, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
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}
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/* Decrement futex @f value and wake up all waiters */
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static inline void futex_dec_and_wake(futex_t *f)
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{
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atomic_dec(&f->raw);
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BUG_ON(sys_futex(&f->raw, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
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}
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/* Plain increment futex @f value */
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static inline void futex_inc(futex_t *f) { f->raw++; }
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/* Plain decrement futex @f value */
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static inline void futex_dec(futex_t *f) { f->raw--; }
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/* Wait until futex @f value become @v */
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static inline void futex_wait_until(futex_t *f, u32 v)
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{ futex_wait_if_cond(f, v, ==); }
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/* Wait while futex @f value is greater than @v */
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static inline void futex_wait_while_gt(futex_t *f, u32 v)
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{ futex_wait_if_cond(f, v, <=); }
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/* Wait while futex @f value is @v */
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static inline void futex_wait_while(futex_t *f, u32 v)
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{
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while (f->raw == v) {
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int ret = sys_futex(&f->raw, FUTEX_WAIT, v, NULL, NULL, 0);
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BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
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}
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}
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typedef struct {
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u32 raw;
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} mutex_t;
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static void inline mutex_init(mutex_t *m)
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{
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u32 c = 0;
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atomic_set(&m->raw, c);
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}
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static void inline mutex_lock(mutex_t *m)
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{
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u32 c;
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int ret;
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while ((c = atomic_inc(&m->raw))) {
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ret = sys_futex(&m->raw, FUTEX_WAIT, c + 1, NULL, NULL, 0);
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BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
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}
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}
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static void inline mutex_unlock(mutex_t *m)
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{
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u32 c = 0;
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atomic_set(&m->raw, c);
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BUG_ON(sys_futex(&m->raw, FUTEX_WAKE, 1, NULL, NULL, 0) < 0);
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}
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#endif /* CR_LOCK_H_ */
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