595 lines
14 KiB
C
595 lines
14 KiB
C
/*
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* Wrappers around mutex/cond/thread functions
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*
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* Copyright Red Hat, Inc. 2009
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*
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* Author:
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* Marcelo Tosatti <mtosatti@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#include "qemu/osdep.h"
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#include "qemu/thread.h"
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#include "qemu/atomic.h"
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#include "qemu/notify.h"
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#include "qemu-thread-common.h"
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#include "qemu/tsan.h"
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static bool name_threads;
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void qemu_thread_naming(bool enable)
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{
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name_threads = enable;
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#ifndef CONFIG_THREAD_SETNAME_BYTHREAD
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/* This is a debugging option, not fatal */
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if (enable) {
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fprintf(stderr, "qemu: thread naming not supported on this host\n");
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}
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#endif
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}
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static void error_exit(int err, const char *msg)
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{
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fprintf(stderr, "qemu: %s: %s\n", msg, strerror(err));
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abort();
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}
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static void compute_abs_deadline(struct timespec *ts, int ms)
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{
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struct timeval tv;
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gettimeofday(&tv, NULL);
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ts->tv_nsec = tv.tv_usec * 1000 + (ms % 1000) * 1000000;
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ts->tv_sec = tv.tv_sec + ms / 1000;
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if (ts->tv_nsec >= 1000000000) {
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ts->tv_sec++;
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ts->tv_nsec -= 1000000000;
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}
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}
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void qemu_mutex_init(QemuMutex *mutex)
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{
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int err;
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err = pthread_mutex_init(&mutex->lock, NULL);
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if (err)
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error_exit(err, __func__);
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qemu_mutex_post_init(mutex);
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}
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void qemu_mutex_destroy(QemuMutex *mutex)
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{
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int err;
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assert(mutex->initialized);
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mutex->initialized = false;
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err = pthread_mutex_destroy(&mutex->lock);
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if (err)
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error_exit(err, __func__);
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}
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void qemu_mutex_lock_impl(QemuMutex *mutex, const char *file, const int line)
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{
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int err;
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assert(mutex->initialized);
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qemu_mutex_pre_lock(mutex, file, line);
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err = pthread_mutex_lock(&mutex->lock);
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if (err)
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error_exit(err, __func__);
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qemu_mutex_post_lock(mutex, file, line);
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}
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int qemu_mutex_trylock_impl(QemuMutex *mutex, const char *file, const int line)
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{
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int err;
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assert(mutex->initialized);
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err = pthread_mutex_trylock(&mutex->lock);
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if (err == 0) {
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qemu_mutex_post_lock(mutex, file, line);
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return 0;
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}
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if (err != EBUSY) {
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error_exit(err, __func__);
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}
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return -EBUSY;
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}
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void qemu_mutex_unlock_impl(QemuMutex *mutex, const char *file, const int line)
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{
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int err;
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assert(mutex->initialized);
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qemu_mutex_pre_unlock(mutex, file, line);
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err = pthread_mutex_unlock(&mutex->lock);
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if (err)
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error_exit(err, __func__);
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}
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void qemu_rec_mutex_init(QemuRecMutex *mutex)
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{
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int err;
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pthread_mutexattr_t attr;
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pthread_mutexattr_init(&attr);
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pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
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err = pthread_mutex_init(&mutex->lock, &attr);
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pthread_mutexattr_destroy(&attr);
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if (err) {
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error_exit(err, __func__);
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}
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mutex->initialized = true;
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}
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void qemu_cond_init(QemuCond *cond)
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{
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int err;
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err = pthread_cond_init(&cond->cond, NULL);
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if (err)
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error_exit(err, __func__);
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cond->initialized = true;
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}
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void qemu_cond_destroy(QemuCond *cond)
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{
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int err;
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assert(cond->initialized);
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cond->initialized = false;
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err = pthread_cond_destroy(&cond->cond);
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if (err)
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error_exit(err, __func__);
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}
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void qemu_cond_signal(QemuCond *cond)
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{
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int err;
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assert(cond->initialized);
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err = pthread_cond_signal(&cond->cond);
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if (err)
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error_exit(err, __func__);
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}
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void qemu_cond_broadcast(QemuCond *cond)
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{
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int err;
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assert(cond->initialized);
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err = pthread_cond_broadcast(&cond->cond);
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if (err)
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error_exit(err, __func__);
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}
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void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex, const char *file, const int line)
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{
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int err;
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assert(cond->initialized);
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qemu_mutex_pre_unlock(mutex, file, line);
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err = pthread_cond_wait(&cond->cond, &mutex->lock);
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qemu_mutex_post_lock(mutex, file, line);
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if (err)
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error_exit(err, __func__);
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}
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bool qemu_cond_timedwait_impl(QemuCond *cond, QemuMutex *mutex, int ms,
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const char *file, const int line)
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{
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int err;
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struct timespec ts;
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assert(cond->initialized);
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trace_qemu_mutex_unlock(mutex, file, line);
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compute_abs_deadline(&ts, ms);
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err = pthread_cond_timedwait(&cond->cond, &mutex->lock, &ts);
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trace_qemu_mutex_locked(mutex, file, line);
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if (err && err != ETIMEDOUT) {
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error_exit(err, __func__);
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}
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return err != ETIMEDOUT;
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}
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void qemu_sem_init(QemuSemaphore *sem, int init)
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{
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int rc;
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#ifndef CONFIG_SEM_TIMEDWAIT
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rc = pthread_mutex_init(&sem->lock, NULL);
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if (rc != 0) {
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error_exit(rc, __func__);
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}
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rc = pthread_cond_init(&sem->cond, NULL);
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if (rc != 0) {
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error_exit(rc, __func__);
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}
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if (init < 0) {
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error_exit(EINVAL, __func__);
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}
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sem->count = init;
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#else
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rc = sem_init(&sem->sem, 0, init);
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if (rc < 0) {
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error_exit(errno, __func__);
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}
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#endif
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sem->initialized = true;
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}
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void qemu_sem_destroy(QemuSemaphore *sem)
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{
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int rc;
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assert(sem->initialized);
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sem->initialized = false;
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#ifndef CONFIG_SEM_TIMEDWAIT
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rc = pthread_cond_destroy(&sem->cond);
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if (rc < 0) {
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error_exit(rc, __func__);
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}
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rc = pthread_mutex_destroy(&sem->lock);
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if (rc < 0) {
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error_exit(rc, __func__);
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}
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#else
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rc = sem_destroy(&sem->sem);
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if (rc < 0) {
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error_exit(errno, __func__);
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}
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#endif
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}
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void qemu_sem_post(QemuSemaphore *sem)
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{
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int rc;
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assert(sem->initialized);
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#ifndef CONFIG_SEM_TIMEDWAIT
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pthread_mutex_lock(&sem->lock);
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if (sem->count == UINT_MAX) {
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rc = EINVAL;
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} else {
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sem->count++;
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rc = pthread_cond_signal(&sem->cond);
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}
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pthread_mutex_unlock(&sem->lock);
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if (rc != 0) {
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error_exit(rc, __func__);
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}
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#else
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rc = sem_post(&sem->sem);
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if (rc < 0) {
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error_exit(errno, __func__);
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}
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#endif
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}
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int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
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{
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int rc;
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struct timespec ts;
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assert(sem->initialized);
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#ifndef CONFIG_SEM_TIMEDWAIT
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rc = 0;
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compute_abs_deadline(&ts, ms);
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pthread_mutex_lock(&sem->lock);
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while (sem->count == 0) {
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rc = pthread_cond_timedwait(&sem->cond, &sem->lock, &ts);
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if (rc == ETIMEDOUT) {
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break;
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}
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if (rc != 0) {
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error_exit(rc, __func__);
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}
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}
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if (rc != ETIMEDOUT) {
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--sem->count;
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}
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pthread_mutex_unlock(&sem->lock);
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return (rc == ETIMEDOUT ? -1 : 0);
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#else
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if (ms <= 0) {
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/* This is cheaper than sem_timedwait. */
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do {
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rc = sem_trywait(&sem->sem);
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} while (rc == -1 && errno == EINTR);
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if (rc == -1 && errno == EAGAIN) {
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return -1;
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}
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} else {
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compute_abs_deadline(&ts, ms);
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do {
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rc = sem_timedwait(&sem->sem, &ts);
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} while (rc == -1 && errno == EINTR);
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if (rc == -1 && errno == ETIMEDOUT) {
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return -1;
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}
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}
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if (rc < 0) {
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error_exit(errno, __func__);
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}
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return 0;
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#endif
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}
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void qemu_sem_wait(QemuSemaphore *sem)
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{
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int rc;
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assert(sem->initialized);
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#ifndef CONFIG_SEM_TIMEDWAIT
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pthread_mutex_lock(&sem->lock);
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while (sem->count == 0) {
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rc = pthread_cond_wait(&sem->cond, &sem->lock);
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if (rc != 0) {
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error_exit(rc, __func__);
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}
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}
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--sem->count;
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pthread_mutex_unlock(&sem->lock);
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#else
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do {
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rc = sem_wait(&sem->sem);
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} while (rc == -1 && errno == EINTR);
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if (rc < 0) {
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error_exit(errno, __func__);
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}
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#endif
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}
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#ifdef __linux__
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#include "qemu/futex.h"
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#else
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static inline void qemu_futex_wake(QemuEvent *ev, int n)
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{
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assert(ev->initialized);
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pthread_mutex_lock(&ev->lock);
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if (n == 1) {
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pthread_cond_signal(&ev->cond);
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} else {
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pthread_cond_broadcast(&ev->cond);
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}
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pthread_mutex_unlock(&ev->lock);
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}
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static inline void qemu_futex_wait(QemuEvent *ev, unsigned val)
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{
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assert(ev->initialized);
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pthread_mutex_lock(&ev->lock);
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if (ev->value == val) {
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pthread_cond_wait(&ev->cond, &ev->lock);
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}
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pthread_mutex_unlock(&ev->lock);
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}
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#endif
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/* Valid transitions:
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* - free->set, when setting the event
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* - busy->set, when setting the event, followed by qemu_futex_wake
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* - set->free, when resetting the event
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* - free->busy, when waiting
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*
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* set->busy does not happen (it can be observed from the outside but
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* it really is set->free->busy).
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*
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* busy->free provably cannot happen; to enforce it, the set->free transition
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* is done with an OR, which becomes a no-op if the event has concurrently
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* transitioned to free or busy.
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*/
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#define EV_SET 0
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#define EV_FREE 1
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#define EV_BUSY -1
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void qemu_event_init(QemuEvent *ev, bool init)
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{
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#ifndef __linux__
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pthread_mutex_init(&ev->lock, NULL);
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pthread_cond_init(&ev->cond, NULL);
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#endif
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ev->value = (init ? EV_SET : EV_FREE);
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ev->initialized = true;
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}
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void qemu_event_destroy(QemuEvent *ev)
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{
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assert(ev->initialized);
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ev->initialized = false;
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#ifndef __linux__
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pthread_mutex_destroy(&ev->lock);
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pthread_cond_destroy(&ev->cond);
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#endif
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}
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void qemu_event_set(QemuEvent *ev)
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{
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/* qemu_event_set has release semantics, but because it *loads*
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* ev->value we need a full memory barrier here.
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*/
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assert(ev->initialized);
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smp_mb();
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if (qatomic_read(&ev->value) != EV_SET) {
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if (qatomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
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/* There were waiters, wake them up. */
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qemu_futex_wake(ev, INT_MAX);
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}
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}
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}
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void qemu_event_reset(QemuEvent *ev)
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{
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unsigned value;
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assert(ev->initialized);
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value = qatomic_read(&ev->value);
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smp_mb_acquire();
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if (value == EV_SET) {
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/*
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* If there was a concurrent reset (or even reset+wait),
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* do nothing. Otherwise change EV_SET->EV_FREE.
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*/
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qatomic_or(&ev->value, EV_FREE);
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}
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}
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void qemu_event_wait(QemuEvent *ev)
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{
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unsigned value;
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assert(ev->initialized);
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value = qatomic_read(&ev->value);
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smp_mb_acquire();
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if (value != EV_SET) {
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if (value == EV_FREE) {
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/*
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* Leave the event reset and tell qemu_event_set that there
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* are waiters. No need to retry, because there cannot be
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* a concurrent busy->free transition. After the CAS, the
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* event will be either set or busy.
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*/
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if (qatomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
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return;
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}
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}
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qemu_futex_wait(ev, EV_BUSY);
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}
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}
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static __thread NotifierList thread_exit;
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/*
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* Note that in this implementation you can register a thread-exit
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* notifier for the main thread, but it will never be called.
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* This is OK because main thread exit can only happen when the
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* entire process is exiting, and the API allows notifiers to not
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* be called on process exit.
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*/
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void qemu_thread_atexit_add(Notifier *notifier)
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{
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notifier_list_add(&thread_exit, notifier);
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}
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void qemu_thread_atexit_remove(Notifier *notifier)
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{
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notifier_remove(notifier);
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}
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static void qemu_thread_atexit_notify(void *arg)
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{
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/*
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* Called when non-main thread exits (via qemu_thread_exit()
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* or by returning from its start routine.)
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*/
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notifier_list_notify(&thread_exit, NULL);
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}
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typedef struct {
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void *(*start_routine)(void *);
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void *arg;
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char *name;
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} QemuThreadArgs;
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static void *qemu_thread_start(void *args)
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{
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QemuThreadArgs *qemu_thread_args = args;
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void *(*start_routine)(void *) = qemu_thread_args->start_routine;
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void *arg = qemu_thread_args->arg;
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void *r;
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#ifdef CONFIG_THREAD_SETNAME_BYTHREAD
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/* Attempt to set the threads name; note that this is for debug, so
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* we're not going to fail if we can't set it.
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*/
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if (name_threads && qemu_thread_args->name) {
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# if defined(CONFIG_PTHREAD_SETNAME_NP_W_TID)
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pthread_setname_np(pthread_self(), qemu_thread_args->name);
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# elif defined(CONFIG_PTHREAD_SETNAME_NP_WO_TID)
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pthread_setname_np(qemu_thread_args->name);
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# endif
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}
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#endif
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QEMU_TSAN_ANNOTATE_THREAD_NAME(qemu_thread_args->name);
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g_free(qemu_thread_args->name);
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g_free(qemu_thread_args);
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pthread_cleanup_push(qemu_thread_atexit_notify, NULL);
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r = start_routine(arg);
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pthread_cleanup_pop(1);
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return r;
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}
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void qemu_thread_create(QemuThread *thread, const char *name,
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void *(*start_routine)(void*),
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void *arg, int mode)
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{
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sigset_t set, oldset;
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int err;
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pthread_attr_t attr;
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QemuThreadArgs *qemu_thread_args;
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err = pthread_attr_init(&attr);
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if (err) {
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error_exit(err, __func__);
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}
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if (mode == QEMU_THREAD_DETACHED) {
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pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
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}
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/* Leave signal handling to the iothread. */
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sigfillset(&set);
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/* Blocking the signals can result in undefined behaviour. */
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sigdelset(&set, SIGSEGV);
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sigdelset(&set, SIGFPE);
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sigdelset(&set, SIGILL);
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/* TODO avoid SIGBUS loss on macOS */
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pthread_sigmask(SIG_SETMASK, &set, &oldset);
|
|
|
|
qemu_thread_args = g_new0(QemuThreadArgs, 1);
|
|
qemu_thread_args->name = g_strdup(name);
|
|
qemu_thread_args->start_routine = start_routine;
|
|
qemu_thread_args->arg = arg;
|
|
|
|
err = pthread_create(&thread->thread, &attr,
|
|
qemu_thread_start, qemu_thread_args);
|
|
|
|
if (err)
|
|
error_exit(err, __func__);
|
|
|
|
pthread_sigmask(SIG_SETMASK, &oldset, NULL);
|
|
|
|
pthread_attr_destroy(&attr);
|
|
}
|
|
|
|
void qemu_thread_get_self(QemuThread *thread)
|
|
{
|
|
thread->thread = pthread_self();
|
|
}
|
|
|
|
bool qemu_thread_is_self(QemuThread *thread)
|
|
{
|
|
return pthread_equal(pthread_self(), thread->thread);
|
|
}
|
|
|
|
void qemu_thread_exit(void *retval)
|
|
{
|
|
pthread_exit(retval);
|
|
}
|
|
|
|
void *qemu_thread_join(QemuThread *thread)
|
|
{
|
|
int err;
|
|
void *ret;
|
|
|
|
err = pthread_join(thread->thread, &ret);
|
|
if (err) {
|
|
error_exit(err, __func__);
|
|
}
|
|
return ret;
|
|
}
|