--- /dev/null
+/*
+ * Wrappers around mutex/cond/thread functions
+ *
+ * Copyright Red Hat, Inc. 2009
+ *
+ * Author:
+ * Marcelo Tosatti <mtosatti@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <time.h>
+#include <signal.h>
+#include <stdint.h>
+#include <string.h>
+#include <limits.h>
+#include <unistd.h>
+#include <sys/time.h>
+#ifdef __linux__
+#include <sys/syscall.h>
+#include <linux/futex.h>
+#endif
+#include "qemu/thread.h"
+#include "qemu/atomic.h"
+#include "qemu/notify.h"
+
+static bool name_threads;
+
+void qemu_thread_naming(bool enable)
+{
+ name_threads = enable;
+
+#ifndef CONFIG_THREAD_SETNAME_BYTHREAD
+ /* This is a debugging option, not fatal */
+ if (enable) {
+ fprintf(stderr, "qemu: thread naming not supported on this host\n");
+ }
+#endif
+}
+
+static void error_exit(int err, const char *msg)
+{
+ fprintf(stderr, "qemu: %s: %s\n", msg, strerror(err));
+ abort();
+}
+
+void qemu_mutex_init(QemuMutex *mutex)
+{
+ int err;
+
+ err = pthread_mutex_init(&mutex->lock, NULL);
+ if (err)
+ error_exit(err, __func__);
+}
+
+void qemu_mutex_destroy(QemuMutex *mutex)
+{
+ int err;
+
+ err = pthread_mutex_destroy(&mutex->lock);
+ if (err)
+ error_exit(err, __func__);
+}
+
+void qemu_mutex_lock(QemuMutex *mutex)
+{
+ int err;
+
+ err = pthread_mutex_lock(&mutex->lock);
+ if (err)
+ error_exit(err, __func__);
+}
+
+int qemu_mutex_trylock(QemuMutex *mutex)
+{
+ return pthread_mutex_trylock(&mutex->lock);
+}
+
+void qemu_mutex_unlock(QemuMutex *mutex)
+{
+ int err;
+
+ err = pthread_mutex_unlock(&mutex->lock);
+ if (err)
+ error_exit(err, __func__);
+}
+
+void qemu_cond_init(QemuCond *cond)
+{
+ int err;
+
+ err = pthread_cond_init(&cond->cond, NULL);
+ if (err)
+ error_exit(err, __func__);
+}
+
+void qemu_cond_destroy(QemuCond *cond)
+{
+ int err;
+
+ err = pthread_cond_destroy(&cond->cond);
+ if (err)
+ error_exit(err, __func__);
+}
+
+void qemu_cond_signal(QemuCond *cond)
+{
+ int err;
+
+ err = pthread_cond_signal(&cond->cond);
+ if (err)
+ error_exit(err, __func__);
+}
+
+void qemu_cond_broadcast(QemuCond *cond)
+{
+ int err;
+
+ err = pthread_cond_broadcast(&cond->cond);
+ if (err)
+ error_exit(err, __func__);
+}
+
+void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex)
+{
+ int err;
+
+ err = pthread_cond_wait(&cond->cond, &mutex->lock);
+ if (err)
+ error_exit(err, __func__);
+}
+
+void qemu_sem_init(QemuSemaphore *sem, int init)
+{
+ int rc;
+
+#if defined(__APPLE__) || defined(__NetBSD__)
+ rc = pthread_mutex_init(&sem->lock, NULL);
+ if (rc != 0) {
+ error_exit(rc, __func__);
+ }
+ rc = pthread_cond_init(&sem->cond, NULL);
+ if (rc != 0) {
+ error_exit(rc, __func__);
+ }
+ if (init < 0) {
+ error_exit(EINVAL, __func__);
+ }
+ sem->count = init;
+#else
+ rc = sem_init(&sem->sem, 0, init);
+ if (rc < 0) {
+ error_exit(errno, __func__);
+ }
+#endif
+}
+
+void qemu_sem_destroy(QemuSemaphore *sem)
+{
+ int rc;
+
+#if defined(__APPLE__) || defined(__NetBSD__)
+ rc = pthread_cond_destroy(&sem->cond);
+ if (rc < 0) {
+ error_exit(rc, __func__);
+ }
+ rc = pthread_mutex_destroy(&sem->lock);
+ 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)
+{
+ int rc;
+
+#if defined(__APPLE__) || defined(__NetBSD__)
+ pthread_mutex_lock(&sem->lock);
+ if (sem->count == UINT_MAX) {
+ rc = EINVAL;
+ } else {
+ sem->count++;
+ rc = pthread_cond_signal(&sem->cond);
+ }
+ pthread_mutex_unlock(&sem->lock);
+ if (rc != 0) {
+ error_exit(rc, __func__);
+ }
+#else
+ rc = sem_post(&sem->sem);
+ if (rc < 0) {
+ error_exit(errno, __func__);
+ }
+#endif
+}
+
+static void compute_abs_deadline(struct timespec *ts, int ms)
+{
+ struct timeval tv;
+ gettimeofday(&tv, NULL);
+ ts->tv_nsec = tv.tv_usec * 1000 + (ms % 1000) * 1000000;
+ ts->tv_sec = tv.tv_sec + ms / 1000;
+ if (ts->tv_nsec >= 1000000000) {
+ ts->tv_sec++;
+ ts->tv_nsec -= 1000000000;
+ }
+}
+
+int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
+{
+ int rc;
+ struct timespec ts;
+
+#if defined(__APPLE__) || defined(__NetBSD__)
+ rc = 0;
+ compute_abs_deadline(&ts, ms);
+ pthread_mutex_lock(&sem->lock);
+ while (sem->count == 0) {
+ rc = pthread_cond_timedwait(&sem->cond, &sem->lock, &ts);
+ if (rc == ETIMEDOUT) {
+ break;
+ }
+ if (rc != 0) {
+ error_exit(rc, __func__);
+ }
+ }
+ if (rc != ETIMEDOUT) {
+ --sem->count;
+ }
+ 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)
+{
+ int rc;
+
+#if defined(__APPLE__) || defined(__NetBSD__)
+ pthread_mutex_lock(&sem->lock);
+ while (sem->count == 0) {
+ rc = pthread_cond_wait(&sem->cond, &sem->lock);
+ if (rc != 0) {
+ error_exit(rc, __func__);
+ }
+ }
+ --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__
+#define futex(...) syscall(__NR_futex, __VA_ARGS__)
+
+static inline void futex_wake(QemuEvent *ev, int n)
+{
+ futex(ev, FUTEX_WAKE, n, NULL, NULL, 0);
+}
+
+static inline void futex_wait(QemuEvent *ev, unsigned val)
+{
+ futex(ev, FUTEX_WAIT, (int) val, NULL, NULL, 0);
+}
+#else
+static inline void futex_wake(QemuEvent *ev, int n)
+{
+ pthread_mutex_lock(&ev->lock);
+ if (n == 1) {
+ pthread_cond_signal(&ev->cond);
+ } else {
+ pthread_cond_broadcast(&ev->cond);
+ }
+ pthread_mutex_unlock(&ev->lock);
+}
+
+static inline void futex_wait(QemuEvent *ev, unsigned val)
+{
+ pthread_mutex_lock(&ev->lock);
+ if (ev->value == val) {
+ pthread_cond_wait(&ev->cond, &ev->lock);
+ }
+ pthread_mutex_unlock(&ev->lock);
+}
+#endif
+
+/* Valid transitions:
+ * - free->set, when setting the event
+ * - busy->set, when setting the event, followed by futex_wake
+ * - set->free, when resetting the event
+ * - free->busy, when waiting
+ *
+ * set->busy does not happen (it can be observed from the outside but
+ * it really is set->free->busy).
+ *
+ * busy->free provably cannot happen; to enforce it, the set->free transition
+ * is done with an OR, which becomes a no-op if the event has concurrently
+ * transitioned to free or busy.
+ */
+
+#define EV_SET 0
+#define EV_FREE 1
+#define EV_BUSY -1
+
+void qemu_event_init(QemuEvent *ev, bool init)
+{
+#ifndef __linux__
+ pthread_mutex_init(&ev->lock, NULL);
+ pthread_cond_init(&ev->cond, NULL);
+#endif
+
+ ev->value = (init ? EV_SET : EV_FREE);
+}
+
+void qemu_event_destroy(QemuEvent *ev)
+{
+#ifndef __linux__
+ pthread_mutex_destroy(&ev->lock);
+ pthread_cond_destroy(&ev->cond);
+#endif
+}
+
+void qemu_event_set(QemuEvent *ev)
+{
+ if (atomic_mb_read(&ev->value) != EV_SET) {
+ if (atomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
+ /* There were waiters, wake them up. */
+ futex_wake(ev, INT_MAX);
+ }
+ }
+}
+
+void qemu_event_reset(QemuEvent *ev)
+{
+ if (atomic_mb_read(&ev->value) == EV_SET) {
+ /*
+ * If there was a concurrent reset (or even reset+wait),
+ * do nothing. Otherwise change EV_SET->EV_FREE.
+ */
+ atomic_or(&ev->value, EV_FREE);
+ }
+}
+
+void qemu_event_wait(QemuEvent *ev)
+{
+ unsigned value;
+
+ value = atomic_mb_read(&ev->value);
+ if (value != EV_SET) {
+ if (value == EV_FREE) {
+ /*
+ * Leave the event reset and tell qemu_event_set that there
+ * are waiters. No need to retry, because there cannot be
+ * a concurent busy->free transition. After the CAS, the
+ * event will be either set or busy.
+ */
+ if (atomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
+ return;
+ }
+ }
+ futex_wait(ev, EV_BUSY);
+ }
+}
+
+static pthread_key_t exit_key;
+
+union NotifierThreadData {
+ void *ptr;
+ NotifierList list;
+};
+QEMU_BUILD_BUG_ON(sizeof(union NotifierThreadData) != sizeof(void *));
+
+void qemu_thread_atexit_add(Notifier *notifier)
+{
+ union NotifierThreadData ntd;
+ ntd.ptr = pthread_getspecific(exit_key);
+ notifier_list_add(&ntd.list, notifier);
+ pthread_setspecific(exit_key, ntd.ptr);
+}
+
+void qemu_thread_atexit_remove(Notifier *notifier)
+{
+ union NotifierThreadData ntd;
+ ntd.ptr = pthread_getspecific(exit_key);
+ notifier_remove(notifier);
+ pthread_setspecific(exit_key, ntd.ptr);
+}
+
+static void qemu_thread_atexit_run(void *arg)
+{
+ union NotifierThreadData ntd = { .ptr = arg };
+ notifier_list_notify(&ntd.list, NULL);
+}
+
+static void __attribute__((constructor)) qemu_thread_atexit_init(void)
+{
+ pthread_key_create(&exit_key, qemu_thread_atexit_run);
+}
+
+
+/* Attempt to set the threads name; note that this is for debug, so
+ * we're not going to fail if we can't set it.
+ */
+static void qemu_thread_set_name(QemuThread *thread, const char *name)
+{
+#ifdef CONFIG_PTHREAD_SETNAME_NP
+ pthread_setname_np(thread->thread, name);
+#endif
+}
+
+void qemu_thread_create(QemuThread *thread, const char *name,
+ void *(*start_routine)(void*),
+ void *arg, int mode)
+{
+ sigset_t set, oldset;
+ int err;
+ pthread_attr_t attr;
+
+ err = pthread_attr_init(&attr);
+ if (err) {
+ error_exit(err, __func__);
+ }
+ if (mode == QEMU_THREAD_DETACHED) {
+ err = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+ if (err) {
+ error_exit(err, __func__);
+ }
+ }
+
+ /* Leave signal handling to the iothread. */
+ sigfillset(&set);
+ pthread_sigmask(SIG_SETMASK, &set, &oldset);
+ err = pthread_create(&thread->thread, &attr, start_routine, arg);
+ if (err)
+ error_exit(err, __func__);
+
+ if (name_threads) {
+ qemu_thread_set_name(thread, name);
+ }
+
+ 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;
+}
Code Review / kvmfornfv.git / blobdiff