diff options
Diffstat (limited to 'qemu/util/qemu-thread-posix.c')
| -rw-r--r-- | qemu/util/qemu-thread-posix.c | 509 |
1 files changed, 509 insertions, 0 deletions
diff --git a/qemu/util/qemu-thread-posix.c b/qemu/util/qemu-thread-posix.c new file mode 100644 index 000000000..ba67cec62 --- /dev/null +++ b/qemu/util/qemu-thread-posix.c @@ -0,0 +1,509 @@ +/* + * 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; +} |