mirror of
https://github.com/checkpoint-restore/criu.git
synced 2026-07-18 00:58:31 +00:00
d7961998bd
In commit 71cc2733a7
I occasionally dropped the ability to abort on waiting
(because we used signed -1 value to inform waiters that
something is wrong and waiting should be aborted, but
the type was changed to unsigned one and as result
this condition never triggers).
So to resolve it futex_abort_and_wake() is added and
should be used explicitly where appropriate instead
if signess hack.
Reported-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
124 lines
2.8 KiB
C
124 lines
2.8 KiB
C
#ifndef CR_LOCK_H_
|
|
#define CR_LOCK_H_
|
|
|
|
#include <linux/futex.h>
|
|
#include <sys/time.h>
|
|
#include <limits.h>
|
|
#include <errno.h>
|
|
|
|
#include "types.h"
|
|
#include "atomic.h"
|
|
#include "syscall.h"
|
|
#include "util.h"
|
|
|
|
typedef struct {
|
|
u32 raw;
|
|
} futex_t;
|
|
|
|
#define FUTEX_ABORT_FLAG (0x80000000)
|
|
#define FUTEX_ABORT_RAW (-1U)
|
|
|
|
/* Get current futex @f value */
|
|
static inline u32 futex_get(futex_t *f)
|
|
{
|
|
return atomic_get(&f->raw);
|
|
}
|
|
|
|
/* Set futex @f value to @v */
|
|
static inline void futex_set(futex_t *f, u32 v)
|
|
{
|
|
atomic_set(&f->raw, v);
|
|
}
|
|
|
|
#define futex_init(f) futex_set(f, 0)
|
|
|
|
/* Wait on futex @__f value @__v become in condition @__c */
|
|
#define futex_wait_if_cond(__f, __v, __cond) \
|
|
do { \
|
|
int ret; \
|
|
u32 tmp; \
|
|
\
|
|
while (1) { \
|
|
tmp = (__f)->raw; \
|
|
if ((tmp & FUTEX_ABORT_FLAG) || \
|
|
(tmp __cond (__v))) \
|
|
break; \
|
|
ret = sys_futex(&(__f)->raw, FUTEX_WAIT,\
|
|
tmp, NULL, NULL, 0); \
|
|
BUG_ON(ret < 0 && ret != -EWOULDBLOCK); \
|
|
} \
|
|
} while (0)
|
|
|
|
/* Set futex @f to @v and wake up all waiters */
|
|
static inline void futex_set_and_wake(futex_t *f, u32 v)
|
|
{
|
|
atomic_set(&f->raw, v);
|
|
BUG_ON(sys_futex(&f->raw, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
|
|
}
|
|
|
|
/* Mark futex @f as wait abort needed and wake up all waiters */
|
|
static inline void futex_abort_and_wake(futex_t *f)
|
|
{
|
|
BUILD_BUG_ON(!(FUTEX_ABORT_RAW & FUTEX_ABORT_FLAG));
|
|
futex_set_and_wake(f, FUTEX_ABORT_RAW);
|
|
}
|
|
|
|
/* Decrement futex @f value and wake up all waiters */
|
|
static inline void futex_dec_and_wake(futex_t *f)
|
|
{
|
|
atomic_dec(&f->raw);
|
|
BUG_ON(sys_futex(&f->raw, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
|
|
}
|
|
|
|
/* Plain increment futex @f value */
|
|
static inline void futex_inc(futex_t *f) { f->raw++; }
|
|
|
|
/* Plain decrement futex @f value */
|
|
static inline void futex_dec(futex_t *f) { f->raw--; }
|
|
|
|
/* Wait until futex @f value become @v */
|
|
static inline void futex_wait_until(futex_t *f, u32 v)
|
|
{ futex_wait_if_cond(f, v, ==); }
|
|
|
|
/* Wait while futex @f value is greater than @v */
|
|
static inline void futex_wait_while_gt(futex_t *f, u32 v)
|
|
{ futex_wait_if_cond(f, v, <=); }
|
|
|
|
/* Wait while futex @f value is @v */
|
|
static inline void futex_wait_while(futex_t *f, u32 v)
|
|
{
|
|
while (f->raw == v) {
|
|
int ret = sys_futex(&f->raw, FUTEX_WAIT, v, NULL, NULL, 0);
|
|
BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
|
|
}
|
|
}
|
|
|
|
typedef struct {
|
|
u32 raw;
|
|
} mutex_t;
|
|
|
|
static void inline mutex_init(mutex_t *m)
|
|
{
|
|
u32 c = 0;
|
|
atomic_set(&m->raw, c);
|
|
}
|
|
|
|
static void inline mutex_lock(mutex_t *m)
|
|
{
|
|
u32 c;
|
|
int ret;
|
|
|
|
while ((c = atomic_inc(&m->raw))) {
|
|
ret = sys_futex(&m->raw, FUTEX_WAIT, c + 1, NULL, NULL, 0);
|
|
BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
|
|
}
|
|
}
|
|
|
|
static void inline mutex_unlock(mutex_t *m)
|
|
{
|
|
u32 c = 0;
|
|
atomic_set(&m->raw, c);
|
|
BUG_ON(sys_futex(&m->raw, FUTEX_WAKE, 1, NULL, NULL, 0) < 0);
|
|
}
|
|
|
|
#endif /* CR_LOCK_H_ */
|