[mirror_qemu.git] / util / qemu-thread-posix.c

/*
 * 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"

static bool name_threads;

void qemu_thread_naming(bool enable)
{
    name_threads = enable;
}

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;
    pthread_mutexattr_t mutexattr;

    pthread_mutexattr_init(&mutexattr);
    pthread_mutexattr_settype(&mutexattr, PTHREAD_MUTEX_ERRORCHECK);
    err = pthread_mutex_init(&mutex->lock, &mutexattr);
    pthread_mutexattr_destroy(&mutexattr);
    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)
{
    if (n == 1) {
        pthread_cond_signal(&ev->cond);
    } else {
        pthread_cond_broadcast(&ev->cond);
    }
}

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);
    }
}

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__);

#ifdef _GNU_SOURCE
    if (name_threads) {
        pthread_setname_np(thread->thread, name);
    }
#endif

    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;
}
Commit	Line	Data
e5d355d1 AL	1	/*
	2	* Wrappers around mutex/cond/thread functions
	3	*
	4	* Copyright Red Hat, Inc. 2009
	5	*
	6	* Author:
	7	* Marcelo Tosatti <mtosatti@redhat.com>
	8	*
	9	* This work is licensed under the terms of the GNU GPL, version 2 or later.
	10	* See the COPYING file in the top-level directory.
	11	*
	12	*/
	13	#include <stdlib.h>
	14	#include <stdio.h>
	15	#include <errno.h>
	16	#include <time.h>
	17	#include <signal.h>
	18	#include <stdint.h>
	19	#include <string.h>
38b14db3 PB	20	#include <limits.h>
	21	#include <unistd.h>
	22	#include <sys/time.h>
c7c4d063 PB	23	#ifdef __linux__
	24	#include <sys/syscall.h>
	25	#include <linux/futex.h>
	26	#endif
1de7afc9	27	#include "qemu/thread.h"
c7c4d063	28	#include "qemu/atomic.h"
e5d355d1	29
8f480de0 DDAG	30	static bool name_threads;
	31
	32	void qemu_thread_naming(bool enable)
	33	{
	34	name_threads = enable;
	35	}
	36
e5d355d1 AL	37	static void error_exit(int err, const char *msg)
	38	{
	39	fprintf(stderr, "qemu: %s: %s\n", msg, strerror(err));
53380ac3	40	abort();
e5d355d1 AL	41	}
	42
	43	void qemu_mutex_init(QemuMutex *mutex)
	44	{
	45	int err;
89b48b56	46	pthread_mutexattr_t mutexattr;
e5d355d1	47
89b48b56 PB	48	pthread_mutexattr_init(&mutexattr);
	49	pthread_mutexattr_settype(&mutexattr, PTHREAD_MUTEX_ERRORCHECK);
	50	err = pthread_mutex_init(&mutex->lock, &mutexattr);
	51	pthread_mutexattr_destroy(&mutexattr);
e5d355d1 AL	52	if (err)
	53	error_exit(err, __func__);
	54	}
	55
313b1d69 CC	56	void qemu_mutex_destroy(QemuMutex *mutex)
	57	{
	58	int err;
	59
	60	err = pthread_mutex_destroy(&mutex->lock);
	61	if (err)
	62	error_exit(err, __func__);
	63	}
	64
e5d355d1 AL	65	void qemu_mutex_lock(QemuMutex *mutex)
	66	{
	67	int err;
	68
	69	err = pthread_mutex_lock(&mutex->lock);
	70	if (err)
	71	error_exit(err, __func__);
	72	}
	73
	74	int qemu_mutex_trylock(QemuMutex *mutex)
	75	{
	76	return pthread_mutex_trylock(&mutex->lock);
	77	}
	78
e5d355d1 AL	79	void qemu_mutex_unlock(QemuMutex *mutex)
	80	{
	81	int err;
	82
	83	err = pthread_mutex_unlock(&mutex->lock);
	84	if (err)
	85	error_exit(err, __func__);
	86	}
	87
	88	void qemu_cond_init(QemuCond *cond)
	89	{
	90	int err;
	91
	92	err = pthread_cond_init(&cond->cond, NULL);
	93	if (err)
	94	error_exit(err, __func__);
	95	}
	96
313b1d69 CC	97	void qemu_cond_destroy(QemuCond *cond)
	98	{
	99	int err;
	100
	101	err = pthread_cond_destroy(&cond->cond);
	102	if (err)
	103	error_exit(err, __func__);
	104	}
	105
e5d355d1 AL	106	void qemu_cond_signal(QemuCond *cond)
	107	{
	108	int err;
	109
	110	err = pthread_cond_signal(&cond->cond);
	111	if (err)
	112	error_exit(err, __func__);
	113	}
	114
	115	void qemu_cond_broadcast(QemuCond *cond)
	116	{
	117	int err;
	118
	119	err = pthread_cond_broadcast(&cond->cond);
	120	if (err)
	121	error_exit(err, __func__);
	122	}
	123
	124	void qemu_cond_wait(QemuCond cond, QemuMutex mutex)
	125	{
	126	int err;
	127
	128	err = pthread_cond_wait(&cond->cond, &mutex->lock);
	129	if (err)
	130	error_exit(err, __func__);
	131	}
	132
38b14db3 PB	133	void qemu_sem_init(QemuSemaphore *sem, int init)
	134	{
	135	int rc;
	136
927fa909	137	#if defined(__APPLE__) \|\| defined(__NetBSD__)
c166cb72 PB	138	rc = pthread_mutex_init(&sem->lock, NULL);
	139	if (rc != 0) {
	140	error_exit(rc, __func__);
	141	}
	142	rc = pthread_cond_init(&sem->cond, NULL);
	143	if (rc != 0) {
	144	error_exit(rc, __func__);
	145	}
	146	if (init < 0) {
	147	error_exit(EINVAL, __func__);
	148	}
	149	sem->count = init;
	150	#else
38b14db3 PB	151	rc = sem_init(&sem->sem, 0, init);
	152	if (rc < 0) {
	153	error_exit(errno, __func__);
	154	}
c166cb72	155	#endif
38b14db3 PB	156	}
	157
	158	void qemu_sem_destroy(QemuSemaphore *sem)
	159	{
	160	int rc;
	161
927fa909	162	#if defined(__APPLE__) \|\| defined(__NetBSD__)
c166cb72 PB	163	rc = pthread_cond_destroy(&sem->cond);
	164	if (rc < 0) {
	165	error_exit(rc, __func__);
	166	}
	167	rc = pthread_mutex_destroy(&sem->lock);
	168	if (rc < 0) {
	169	error_exit(rc, __func__);
	170	}
	171	#else
38b14db3 PB	172	rc = sem_destroy(&sem->sem);
	173	if (rc < 0) {
	174	error_exit(errno, __func__);
	175	}
c166cb72	176	#endif
38b14db3 PB	177	}
	178
	179	void qemu_sem_post(QemuSemaphore *sem)
	180	{
	181	int rc;
	182
927fa909	183	#if defined(__APPLE__) \|\| defined(__NetBSD__)
c166cb72	184	pthread_mutex_lock(&sem->lock);
79761c66	185	if (sem->count == UINT_MAX) {
c166cb72	186	rc = EINVAL;
c166cb72	187	} else {
79761c66 IT	188	sem->count++;
79761c66 IT	189	rc = pthread_cond_signal(&sem->cond);
c166cb72 PB	190	}
	191	pthread_mutex_unlock(&sem->lock);
	192	if (rc != 0) {
	193	error_exit(rc, __func__);
	194	}
	195	#else
38b14db3 PB	196	rc = sem_post(&sem->sem);
	197	if (rc < 0) {
	198	error_exit(errno, __func__);
	199	}
c166cb72 PB	200	#endif
	201	}
	202
	203	static void compute_abs_deadline(struct timespec *ts, int ms)
	204	{
	205	struct timeval tv;
	206	gettimeofday(&tv, NULL);
	207	ts->tv_nsec = tv.tv_usec * 1000 + (ms % 1000) * 1000000;
	208	ts->tv_sec = tv.tv_sec + ms / 1000;
	209	if (ts->tv_nsec >= 1000000000) {
	210	ts->tv_sec++;
	211	ts->tv_nsec -= 1000000000;
	212	}
38b14db3 PB	213	}
	214
	215	int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
	216	{
	217	int rc;
c166cb72 PB	218	struct timespec ts;
c166cb72 PB	219
927fa909	220	#if defined(__APPLE__) \|\| defined(__NetBSD__)
79761c66	221	rc = 0;
c166cb72 PB	222	compute_abs_deadline(&ts, ms);
c166cb72 PB	223	pthread_mutex_lock(&sem->lock);
79761c66	224	while (sem->count == 0) {
c166cb72 PB	225	rc = pthread_cond_timedwait(&sem->cond, &sem->lock, &ts);
	226	if (rc == ETIMEDOUT) {
	227	break;
	228	}
	229	if (rc != 0) {
	230	error_exit(rc, __func__);
	231	}
	232	}
79761c66 IT	233	if (rc != ETIMEDOUT) {
	234	--sem->count;
	235	}
c166cb72 PB	236	pthread_mutex_unlock(&sem->lock);
	237	return (rc == ETIMEDOUT ? -1 : 0);
	238	#else
38b14db3 PB	239	if (ms <= 0) {
	240	/* This is cheaper than sem_timedwait. */
	241	do {
	242	rc = sem_trywait(&sem->sem);
	243	} while (rc == -1 && errno == EINTR);
	244	if (rc == -1 && errno == EAGAIN) {
	245	return -1;
	246	}
	247	} else {
c166cb72	248	compute_abs_deadline(&ts, ms);
38b14db3 PB	249	do {
	250	rc = sem_timedwait(&sem->sem, &ts);
	251	} while (rc == -1 && errno == EINTR);
	252	if (rc == -1 && errno == ETIMEDOUT) {
	253	return -1;
	254	}
	255	}
	256	if (rc < 0) {
	257	error_exit(errno, __func__);
	258	}
	259	return 0;
c166cb72	260	#endif
38b14db3 PB	261	}
	262
	263	void qemu_sem_wait(QemuSemaphore *sem)
	264	{
79761c66 IT	265	int rc;
79761c66 IT	266
927fa909	267	#if defined(__APPLE__) \|\| defined(__NetBSD__)
c166cb72	268	pthread_mutex_lock(&sem->lock);
79761c66 IT	269	while (sem->count == 0) {
	270	rc = pthread_cond_wait(&sem->cond, &sem->lock);
	271	if (rc != 0) {
	272	error_exit(rc, __func__);
	273	}
c166cb72	274	}
79761c66	275	--sem->count;
c166cb72 PB	276	pthread_mutex_unlock(&sem->lock);
c166cb72 PB	277	#else
38b14db3 PB	278	do {
	279	rc = sem_wait(&sem->sem);
	280	} while (rc == -1 && errno == EINTR);
	281	if (rc < 0) {
	282	error_exit(errno, __func__);
	283	}
c166cb72	284	#endif
38b14db3 PB	285	}
38b14db3 PB	286
c7c4d063 PB	287	#ifdef __linux__
	288	#define futex(...) syscall(__NR_futex, __VA_ARGS__)
	289
	290	static inline void futex_wake(QemuEvent *ev, int n)
	291	{
	292	futex(ev, FUTEX_WAKE, n, NULL, NULL, 0);
	293	}
	294
	295	static inline void futex_wait(QemuEvent *ev, unsigned val)
	296	{
	297	futex(ev, FUTEX_WAIT, (int) val, NULL, NULL, 0);
	298	}
	299	#else
	300	static inline void futex_wake(QemuEvent *ev, int n)
	301	{
	302	if (n == 1) {
	303	pthread_cond_signal(&ev->cond);
	304	} else {
	305	pthread_cond_broadcast(&ev->cond);
	306	}
	307	}
	308
	309	static inline void futex_wait(QemuEvent *ev, unsigned val)
	310	{
	311	pthread_mutex_lock(&ev->lock);
	312	if (ev->value == val) {
	313	pthread_cond_wait(&ev->cond, &ev->lock);
	314	}
	315	pthread_mutex_unlock(&ev->lock);
	316	}
	317	#endif
	318
	319	/* Valid transitions:
	320	* - free->set, when setting the event
	321	* - busy->set, when setting the event, followed by futex_wake
	322	* - set->free, when resetting the event
	323	* - free->busy, when waiting
	324	*
	325	* set->busy does not happen (it can be observed from the outside but
	326	* it really is set->free->busy).
	327	*
	328	* busy->free provably cannot happen; to enforce it, the set->free transition
	329	* is done with an OR, which becomes a no-op if the event has concurrently
	330	* transitioned to free or busy.
	331	*/
	332
	333	#define EV_SET 0
	334	#define EV_FREE 1
	335	#define EV_BUSY -1
	336
	337	void qemu_event_init(QemuEvent *ev, bool init)
	338	{
	339	#ifndef __linux__
	340	pthread_mutex_init(&ev->lock, NULL);
	341	pthread_cond_init(&ev->cond, NULL);
	342	#endif
	343
	344	ev->value = (init ? EV_SET : EV_FREE);
	345	}
	346
	347	void qemu_event_destroy(QemuEvent *ev)
	348	{
	349	#ifndef __linux__
	350	pthread_mutex_destroy(&ev->lock);
351	pthread_cond_destroy(&ev->cond);
352	#endif
353	}
354
355	void qemu_event_set(QemuEvent *ev)
356	{
357	if (atomic_mb_read(&ev->value) != EV_SET) {
358	if (atomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
359	/* There were waiters, wake them up. */
360	futex_wake(ev, INT_MAX);
361	}
362	}
363	}
364
365	void qemu_event_reset(QemuEvent *ev)
366	{
367	if (atomic_mb_read(&ev->value) == EV_SET) {
368	/*
369	* If there was a concurrent reset (or even reset+wait),
370	* do nothing. Otherwise change EV_SET->EV_FREE.
371	*/
372	atomic_or(&ev->value, EV_FREE);
373	}
374	}
375
376	void qemu_event_wait(QemuEvent *ev)
377	{
378	unsigned value;
379
380	value = atomic_mb_read(&ev->value);
381	if (value != EV_SET) {
382	if (value == EV_FREE) {
383	/*
384	* Leave the event reset and tell qemu_event_set that there
385	* are waiters. No need to retry, because there cannot be
386	* a concurent busy->free transition. After the CAS, the
387	* event will be either set or busy.
388	*/
389	if (atomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
390	return;
391	}
392	}
393	futex_wait(ev, EV_BUSY);
394	}
395	}
396
4900116e	397	void qemu_thread_create(QemuThread thread, const char name,
e5d355d1	398	void (start_routine)(void*),
cf218714	399	void *arg, int mode)
e5d355d1	400	{
cf218714	401	sigset_t set, oldset;
e5d355d1	402	int err;
8763046b	403	pthread_attr_t attr;
e5d355d1	404
8763046b JK	405	err = pthread_attr_init(&attr);
	406	if (err) {
	407	error_exit(err, __func__);
	408	}
	409	if (mode == QEMU_THREAD_DETACHED) {
	410	err = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
	411	if (err) {
	412	error_exit(err, __func__);
	413	}
	414	}
55541c8a	415
cf218714	416	/* Leave signal handling to the iothread. */
55541c8a PB	417	sigfillset(&set);
55541c8a PB	418	pthread_sigmask(SIG_SETMASK, &set, &oldset);
8763046b	419	err = pthread_create(&thread->thread, &attr, start_routine, arg);
e5d355d1 AL	420	if (err)
e5d355d1 AL	421	error_exit(err, __func__);
55541c8a	422
4900116e DDAG	423	#ifdef _GNU_SOURCE
	424	if (name_threads) {
	425	pthread_setname_np(thread->thread, name);
	426	}
	427	#endif
	428
55541c8a	429	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
8763046b JK	430
8763046b JK	431	pthread_attr_destroy(&attr);
e5d355d1 AL	432	}
e5d355d1 AL	433
b7680cb6	434	void qemu_thread_get_self(QemuThread *thread)
e5d355d1 AL	435	{
	436	thread->thread = pthread_self();
	437	}
	438
2d797b65	439	bool qemu_thread_is_self(QemuThread *thread)
e5d355d1	440	{
b7680cb6	441	return pthread_equal(pthread_self(), thread->thread);
e5d355d1 AL	442	}
e5d355d1 AL	443
313b1d69 CC	444	void qemu_thread_exit(void *retval)
	445	{
	446	pthread_exit(retval);
	447	}
8763046b JK	448
	449	void qemu_thread_join(QemuThread thread)
	450	{
	451	int err;
	452	void *ret;
	453
	454	err = pthread_join(thread->thread, &ret);
	455	if (err) {
	456	error_exit(err, __func__);
	457	}
	458	return ret;
	459	}