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#ifndef __CR_COMMON_LOCK_H__
#define __CR_COMMON_LOCK_H__
#include <stdint.h>
#include <stdbool.h>
#include <linux/futex.h>
#include <sys/time.h>
#include <limits.h>
#include <errno.h>
#include "common/asm/atomic.h"
#include "common/compiler.h"
/* scan-build complains about dereferencing a NULL pointer here. */
#ifndef __clang_analyzer__
#define LOCK_BUG_ON(condition) \
if ((condition)) \
*(volatile unsigned long *)NULL = 0xdead0000 + __LINE__
#define LOCK_BUG() LOCK_BUG_ON(1)
#endif /* __clang_analyzer__ */
#ifdef CR_NOGLIBC
#include <compel/plugins/std/syscall.h>
#else
#include <unistd.h>
#include <sys/syscall.h>
static inline long sys_futex(uint32_t *addr1, int op, uint32_t val1, struct timespec *timeout, uint32_t *addr2,
uint32_t val3)
{
int rc = syscall(SYS_futex, addr1, op, val1, timeout, addr2, val3);
if (rc == -1)
rc = -errno;
return rc;
}
#endif
typedef struct {
atomic_t raw;
} __aligned(sizeof(int)) futex_t;
#define FUTEX_ABORT_FLAG (0x80000000)
#define FUTEX_ABORT_RAW (-1U)
/* Get current futex @f value */
static inline uint32_t futex_get(futex_t *f)
{
return atomic_read(&f->raw);
}
/* Set futex @f value to @v */
static inline void futex_set(futex_t *f, uint32_t v)
{
atomic_set(&f->raw, (int)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; \
uint32_t tmp; \
\
while (1) { \
struct timespec to = { .tv_sec = 120 }; \
tmp = futex_get(__f); \
if ((tmp & FUTEX_ABORT_FLAG) || (tmp __cond(__v))) \
break; \
ret = sys_futex((uint32_t *)&(__f)->raw.counter, FUTEX_WAIT, tmp, &to, NULL, 0); \
if (ret == -ETIMEDOUT) \
continue; \
if (ret == -EINTR || ret == -EWOULDBLOCK) \
continue; \
if (ret < 0) \
LOCK_BUG(); \
} \
} while (0)
/* Set futex @f to @v and wake up all waiters */
static inline void futex_set_and_wake(futex_t *f, uint32_t v)
{
atomic_set(&f->raw, (int)v);
LOCK_BUG_ON(sys_futex((uint32_t *)&f->raw.counter, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
}
/* Wake up all futex @f waiters */
static inline void futex_wake(futex_t *f)
{
LOCK_BUG_ON(sys_futex((uint32_t *)&f->raw.counter, 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);
LOCK_BUG_ON(sys_futex((uint32_t *)&f->raw.counter, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
}
/* Increment futex @f value and wake up all waiters */
static inline void futex_inc_and_wake(futex_t *f)
{
atomic_inc(&f->raw);
LOCK_BUG_ON(sys_futex((uint32_t *)&f->raw.counter, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
}
/* Plain increment futex @f value */
static inline void futex_inc(futex_t *f)
{
atomic_inc(&f->raw);
}
/* Plain decrement futex @f value */
static inline void futex_dec(futex_t *f)
{
atomic_dec(&f->raw);
}
/* Wait until futex @f value become @v */
#define futex_wait_until(f, v) futex_wait_if_cond(f, v, ==)
/* Wait while futex @f value is greater than @v */
#define futex_wait_while_gt(f, v) futex_wait_if_cond(f, v, <=)
/* Wait while futex @f value is less than @v */
#define futex_wait_while_lt(f, v) futex_wait_if_cond(f, v, >=)
/* Wait while futex @f value is equal to @v */
#define futex_wait_while_eq(f, v) futex_wait_if_cond(f, v, !=)
/* Wait while futex @f value is @v */
static inline void futex_wait_while(futex_t *f, uint32_t v)
{
while ((uint32_t)atomic_read(&f->raw) == v) {
int ret = sys_futex((uint32_t *)&f->raw.counter, FUTEX_WAIT, v, NULL, NULL, 0);
LOCK_BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
}
}
typedef struct {
atomic_t raw;
} mutex_t;
static inline void mutex_init(mutex_t *m)
{
uint32_t c = 0;
atomic_set(&m->raw, (int)c);
}
static inline void mutex_lock(mutex_t *m)
{
uint32_t c;
int ret;
while ((c = (uint32_t)atomic_inc_return(&m->raw)) != 1) {
ret = sys_futex((uint32_t *)&m->raw.counter, FUTEX_WAIT, c, NULL, NULL, 0);
LOCK_BUG_ON(ret < 0 && ret != -EWOULDBLOCK);
}
}
static inline bool mutex_trylock(mutex_t *m)
{
return atomic_inc_return(&m->raw) == 1;
}
static inline void mutex_unlock(mutex_t *m)
{
uint32_t c = 0;
atomic_set(&m->raw, (int)c);
LOCK_BUG_ON(sys_futex((uint32_t *)&m->raw.counter, FUTEX_WAKE, 1, NULL, NULL, 0) < 0);
}
#endif /* __CR_COMMON_LOCK_H__ */
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