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authorLongpeng(Mike) <longpeng2@huawei.com>2022-02-22 17:05:04 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2022-04-06 14:31:55 +0200
commitf9fc8932b11f3bcf2a2626f567cb6fdd36a33a94 (patch)
treeb3baad6e196328bed2811174d73b6514dcc35ee1 /util/qemu-thread-posix.c
parentd7482ffe9756919531307330fd1c6dbec66e8c32 (diff)
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thread-posix: remove the posix semaphore support
POSIX specifies an absolute time for sem_timedwait(), it would be affected if the system time is changing, but there is not a relative time or monotonic clock version of sem_timedwait, so we cannot gain from POSIX semaphore any more. An alternative way is to use sem_trywait + usleep, maybe we can remove CONFIG_SEM_TIMEDWAIT in this way? No, because some systems (e.g. mac os) mark the sem_xxx API as deprecated. So maybe remove the usage of POSIX semaphore and turn to use the pthread variant for all systems looks better. Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com> Message-Id: <20220222090507.2028-2-longpeng2@huawei.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'util/qemu-thread-posix.c')
-rw-r--r--util/qemu-thread-posix.c54
1 files changed, 0 insertions, 54 deletions
diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
index e1225b6..1ad2503 100644
--- a/util/qemu-thread-posix.c
+++ b/util/qemu-thread-posix.c
@@ -219,7 +219,6 @@ void qemu_sem_init(QemuSemaphore *sem, int init)
{
int rc;
-#ifndef CONFIG_SEM_TIMEDWAIT
rc = pthread_mutex_init(&sem->lock, NULL);
if (rc != 0) {
error_exit(rc, __func__);
@@ -232,12 +231,6 @@ void qemu_sem_init(QemuSemaphore *sem, int init)
error_exit(EINVAL, __func__);
}
sem->count = init;
-#else
- rc = sem_init(&sem->sem, 0, init);
- if (rc < 0) {
- error_exit(errno, __func__);
- }
-#endif
sem->initialized = true;
}
@@ -247,7 +240,6 @@ void qemu_sem_destroy(QemuSemaphore *sem)
assert(sem->initialized);
sem->initialized = false;
-#ifndef CONFIG_SEM_TIMEDWAIT
rc = pthread_cond_destroy(&sem->cond);
if (rc < 0) {
error_exit(rc, __func__);
@@ -256,12 +248,6 @@ void qemu_sem_destroy(QemuSemaphore *sem)
if (rc < 0) {
error_exit(rc, __func__);
}
-#else
- rc = sem_destroy(&sem->sem);
- if (rc < 0) {
- error_exit(errno, __func__);
- }
-#endif
}
void qemu_sem_post(QemuSemaphore *sem)
@@ -269,7 +255,6 @@ void qemu_sem_post(QemuSemaphore *sem)
int rc;
assert(sem->initialized);
-#ifndef CONFIG_SEM_TIMEDWAIT
pthread_mutex_lock(&sem->lock);
if (sem->count == UINT_MAX) {
rc = EINVAL;
@@ -281,12 +266,6 @@ void qemu_sem_post(QemuSemaphore *sem)
if (rc != 0) {
error_exit(rc, __func__);
}
-#else
- rc = sem_post(&sem->sem);
- if (rc < 0) {
- error_exit(errno, __func__);
- }
-#endif
}
int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
@@ -295,7 +274,6 @@ int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
struct timespec ts;
assert(sem->initialized);
-#ifndef CONFIG_SEM_TIMEDWAIT
rc = 0;
compute_abs_deadline(&ts, ms);
pthread_mutex_lock(&sem->lock);
@@ -313,29 +291,6 @@ int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
}
pthread_mutex_unlock(&sem->lock);
return (rc == ETIMEDOUT ? -1 : 0);
-#else
- if (ms <= 0) {
- /* This is cheaper than sem_timedwait. */
- do {
- rc = sem_trywait(&sem->sem);
- } while (rc == -1 && errno == EINTR);
- if (rc == -1 && errno == EAGAIN) {
- return -1;
- }
- } else {
- compute_abs_deadline(&ts, ms);
- do {
- rc = sem_timedwait(&sem->sem, &ts);
- } while (rc == -1 && errno == EINTR);
- if (rc == -1 && errno == ETIMEDOUT) {
- return -1;
- }
- }
- if (rc < 0) {
- error_exit(errno, __func__);
- }
- return 0;
-#endif
}
void qemu_sem_wait(QemuSemaphore *sem)
@@ -343,7 +298,6 @@ void qemu_sem_wait(QemuSemaphore *sem)
int rc;
assert(sem->initialized);
-#ifndef CONFIG_SEM_TIMEDWAIT
pthread_mutex_lock(&sem->lock);
while (sem->count == 0) {
rc = pthread_cond_wait(&sem->cond, &sem->lock);
@@ -353,14 +307,6 @@ void qemu_sem_wait(QemuSemaphore *sem)
}
--sem->count;
pthread_mutex_unlock(&sem->lock);
-#else
- do {
- rc = sem_wait(&sem->sem);
- } while (rc == -1 && errno == EINTR);
- if (rc < 0) {
- error_exit(errno, __func__);
- }
-#endif
}
#ifdef __linux__