qemu/util/qemu-thread-posix.c
Paolo Bonzini 10f6b23187 configure, meson: move pthread_setname_np checks to Meson
This makes the pthreads check dead in configure, so remove it
as well.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20211007130829.632254-9-pbonzini@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-10-14 09:50:57 +02:00

633 lines
15 KiB
C
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/*
* 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 "qemu/osdep.h"
#include "qemu/thread.h"
#include "qemu/atomic.h"
#include "qemu/notify.h"
#include "qemu-thread-common.h"
#include "qemu/tsan.h"
static bool name_threads;
void qemu_thread_naming(bool enable)
{
name_threads = enable;
#if !defined CONFIG_PTHREAD_SETNAME_NP_W_TID && \
!defined CONFIG_PTHREAD_SETNAME_NP_WO_TID
/* 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();
}
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;
}
}
void qemu_mutex_init(QemuMutex *mutex)
{
int err;
err = pthread_mutex_init(&mutex->lock, NULL);
if (err)
error_exit(err, __func__);
qemu_mutex_post_init(mutex);
}
void qemu_mutex_destroy(QemuMutex *mutex)
{
int err;
assert(mutex->initialized);
mutex->initialized = false;
err = pthread_mutex_destroy(&mutex->lock);
if (err)
error_exit(err, __func__);
}
void qemu_mutex_lock_impl(QemuMutex *mutex, const char *file, const int line)
{
int err;
assert(mutex->initialized);
qemu_mutex_pre_lock(mutex, file, line);
err = pthread_mutex_lock(&mutex->lock);
if (err)
error_exit(err, __func__);
qemu_mutex_post_lock(mutex, file, line);
}
int qemu_mutex_trylock_impl(QemuMutex *mutex, const char *file, const int line)
{
int err;
assert(mutex->initialized);
err = pthread_mutex_trylock(&mutex->lock);
if (err == 0) {
qemu_mutex_post_lock(mutex, file, line);
return 0;
}
if (err != EBUSY) {
error_exit(err, __func__);
}
return -EBUSY;
}
void qemu_mutex_unlock_impl(QemuMutex *mutex, const char *file, const int line)
{
int err;
assert(mutex->initialized);
qemu_mutex_pre_unlock(mutex, file, line);
err = pthread_mutex_unlock(&mutex->lock);
if (err)
error_exit(err, __func__);
}
void qemu_rec_mutex_init(QemuRecMutex *mutex)
{
int err;
pthread_mutexattr_t attr;
pthread_mutexattr_init(&attr);
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
err = pthread_mutex_init(&mutex->m.lock, &attr);
pthread_mutexattr_destroy(&attr);
if (err) {
error_exit(err, __func__);
}
mutex->m.initialized = true;
}
void qemu_rec_mutex_destroy(QemuRecMutex *mutex)
{
qemu_mutex_destroy(&mutex->m);
}
void qemu_rec_mutex_lock_impl(QemuRecMutex *mutex, const char *file, int line)
{
qemu_mutex_lock_impl(&mutex->m, file, line);
}
int qemu_rec_mutex_trylock_impl(QemuRecMutex *mutex, const char *file, int line)
{
return qemu_mutex_trylock_impl(&mutex->m, file, line);
}
void qemu_rec_mutex_unlock_impl(QemuRecMutex *mutex, const char *file, int line)
{
qemu_mutex_unlock_impl(&mutex->m, file, line);
}
void qemu_cond_init(QemuCond *cond)
{
int err;
err = pthread_cond_init(&cond->cond, NULL);
if (err)
error_exit(err, __func__);
cond->initialized = true;
}
void qemu_cond_destroy(QemuCond *cond)
{
int err;
assert(cond->initialized);
cond->initialized = false;
err = pthread_cond_destroy(&cond->cond);
if (err)
error_exit(err, __func__);
}
void qemu_cond_signal(QemuCond *cond)
{
int err;
assert(cond->initialized);
err = pthread_cond_signal(&cond->cond);
if (err)
error_exit(err, __func__);
}
void qemu_cond_broadcast(QemuCond *cond)
{
int err;
assert(cond->initialized);
err = pthread_cond_broadcast(&cond->cond);
if (err)
error_exit(err, __func__);
}
void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex, const char *file, const int line)
{
int err;
assert(cond->initialized);
qemu_mutex_pre_unlock(mutex, file, line);
err = pthread_cond_wait(&cond->cond, &mutex->lock);
qemu_mutex_post_lock(mutex, file, line);
if (err)
error_exit(err, __func__);
}
bool qemu_cond_timedwait_impl(QemuCond *cond, QemuMutex *mutex, int ms,
const char *file, const int line)
{
int err;
struct timespec ts;
assert(cond->initialized);
trace_qemu_mutex_unlock(mutex, file, line);
compute_abs_deadline(&ts, ms);
err = pthread_cond_timedwait(&cond->cond, &mutex->lock, &ts);
trace_qemu_mutex_locked(mutex, file, line);
if (err && err != ETIMEDOUT) {
error_exit(err, __func__);
}
return err != ETIMEDOUT;
}
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__);
}
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
sem->initialized = true;
}
void qemu_sem_destroy(QemuSemaphore *sem)
{
int rc;
assert(sem->initialized);
sem->initialized = false;
#ifndef CONFIG_SEM_TIMEDWAIT
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;
assert(sem->initialized);
#ifndef CONFIG_SEM_TIMEDWAIT
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
}
int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
{
int rc;
struct timespec ts;
assert(sem->initialized);
#ifndef CONFIG_SEM_TIMEDWAIT
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;
assert(sem->initialized);
#ifndef CONFIG_SEM_TIMEDWAIT
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__
#include "qemu/futex.h"
#else
static inline void qemu_futex_wake(QemuEvent *ev, int n)
{
assert(ev->initialized);
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 qemu_futex_wait(QemuEvent *ev, unsigned val)
{
assert(ev->initialized);
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 qemu_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);
ev->initialized = true;
}
void qemu_event_destroy(QemuEvent *ev)
{
assert(ev->initialized);
ev->initialized = false;
#ifndef __linux__
pthread_mutex_destroy(&ev->lock);
pthread_cond_destroy(&ev->cond);
#endif
}
void qemu_event_set(QemuEvent *ev)
{
/* qemu_event_set has release semantics, but because it *loads*
* ev->value we need a full memory barrier here.
*/
assert(ev->initialized);
smp_mb();
if (qatomic_read(&ev->value) != EV_SET) {
if (qatomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
/* There were waiters, wake them up. */
qemu_futex_wake(ev, INT_MAX);
}
}
}
void qemu_event_reset(QemuEvent *ev)
{
unsigned value;
assert(ev->initialized);
value = qatomic_read(&ev->value);
smp_mb_acquire();
if (value == EV_SET) {
/*
* If there was a concurrent reset (or even reset+wait),
* do nothing. Otherwise change EV_SET->EV_FREE.
*/
qatomic_or(&ev->value, EV_FREE);
}
}
void qemu_event_wait(QemuEvent *ev)
{
unsigned value;
assert(ev->initialized);
value = qatomic_read(&ev->value);
smp_mb_acquire();
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 concurrent busy->free transition. After the CAS, the
* event will be either set or busy.
*/
if (qatomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
return;
}
}
qemu_futex_wait(ev, EV_BUSY);
}
}
static __thread NotifierList thread_exit;
/*
* Note that in this implementation you can register a thread-exit
* notifier for the main thread, but it will never be called.
* This is OK because main thread exit can only happen when the
* entire process is exiting, and the API allows notifiers to not
* be called on process exit.
*/
void qemu_thread_atexit_add(Notifier *notifier)
{
notifier_list_add(&thread_exit, notifier);
}
void qemu_thread_atexit_remove(Notifier *notifier)
{
notifier_remove(notifier);
}
static void qemu_thread_atexit_notify(void *arg)
{
/*
* Called when non-main thread exits (via qemu_thread_exit()
* or by returning from its start routine.)
*/
notifier_list_notify(&thread_exit, NULL);
}
typedef struct {
void *(*start_routine)(void *);
void *arg;
char *name;
} QemuThreadArgs;
static void *qemu_thread_start(void *args)
{
QemuThreadArgs *qemu_thread_args = args;
void *(*start_routine)(void *) = qemu_thread_args->start_routine;
void *arg = qemu_thread_args->arg;
void *r;
/* 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.
*/
if (name_threads && qemu_thread_args->name) {
# if defined(CONFIG_PTHREAD_SETNAME_NP_W_TID)
pthread_setname_np(pthread_self(), qemu_thread_args->name);
# elif defined(CONFIG_PTHREAD_SETNAME_NP_WO_TID)
pthread_setname_np(qemu_thread_args->name);
# endif
}
QEMU_TSAN_ANNOTATE_THREAD_NAME(qemu_thread_args->name);
g_free(qemu_thread_args->name);
g_free(qemu_thread_args);
/*
* GCC 11 with glibc 2.17 on PowerPC reports
*
* qemu-thread-posix.c:540:5: error: __sigsetjmp accessing 656 bytes
* in a region of size 528 [-Werror=stringop-overflow=]
* 540 | pthread_cleanup_push(qemu_thread_atexit_notify, NULL);
* | ^~~~~~~~~~~~~~~~~~~~
*
* which is clearly nonsense.
*/
#pragma GCC diagnostic push
#ifndef __clang__
#pragma GCC diagnostic ignored "-Wstringop-overflow"
#endif
pthread_cleanup_push(qemu_thread_atexit_notify, NULL);
r = start_routine(arg);
pthread_cleanup_pop(1);
#pragma GCC diagnostic pop
return r;
}
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;
QemuThreadArgs *qemu_thread_args;
err = pthread_attr_init(&attr);
if (err) {
error_exit(err, __func__);
}
if (mode == QEMU_THREAD_DETACHED) {
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
}
/* Leave signal handling to the iothread. */
sigfillset(&set);
/* Blocking the signals can result in undefined behaviour. */
sigdelset(&set, SIGSEGV);
sigdelset(&set, SIGFPE);
sigdelset(&set, SIGILL);
/* TODO avoid SIGBUS loss on macOS */
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;
}