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* QEMU VNC display driver
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* Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
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* Copyright (C) 2006 Fabrice Bellard
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* Copyright (C) 2009 Red Hat, Inc
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* Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* There is three levels of locking:
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* - jobs queue lock: for each operation on the queue (push, pop, isEmpty?)
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* - VncDisplay global lock: mainly used for framebuffer updates to avoid
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* screen corruption if the framebuffer is updated
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* while the worker is doing something.
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* - VncState::output lock: used to make sure the output buffer is not corrupted
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* if two threads try to write on it at the same time
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* While the VNC worker thread is working, the VncDisplay global lock is hold
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* to avoid screen corruptions (this does not block vnc_refresh() because it
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* uses trylock()) but the output lock is not hold because the thread work on
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* its own output buffer.
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* When the encoding job is done, the worker thread will hold the output lock
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* and copy its output buffer in vs->output.
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QTAILQ_HEAD(, VncJob) jobs;
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typedef struct VncJobQueue VncJobQueue;
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* We use a single global queue, but most of the functions are
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* already reetrant, so we can easilly add more than one encoding thread
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static VncJobQueue *queue;
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static void vnc_lock_queue(VncJobQueue *queue)
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qemu_mutex_lock(&queue->mutex);
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static void vnc_unlock_queue(VncJobQueue *queue)
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qemu_mutex_unlock(&queue->mutex);
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VncJob *vnc_job_new(VncState *vs)
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VncJob *job = g_malloc0(sizeof(VncJob));
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vnc_lock_queue(queue);
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QLIST_INIT(&job->rectangles);
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vnc_unlock_queue(queue);
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int vnc_job_add_rect(VncJob *job, int x, int y, int w, int h)
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VncRectEntry *entry = g_malloc0(sizeof(VncRectEntry));
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vnc_lock_queue(queue);
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QLIST_INSERT_HEAD(&job->rectangles, entry, next);
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vnc_unlock_queue(queue);
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void vnc_job_push(VncJob *job)
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vnc_lock_queue(queue);
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if (queue->exit || QLIST_EMPTY(&job->rectangles)) {
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QTAILQ_INSERT_TAIL(&queue->jobs, job, next);
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qemu_cond_broadcast(&queue->cond);
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vnc_unlock_queue(queue);
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static bool vnc_has_job_locked(VncState *vs)
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QTAILQ_FOREACH(job, &queue->jobs, next) {
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if (job->vs == vs || !vs) {
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bool vnc_has_job(VncState *vs)
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vnc_lock_queue(queue);
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ret = vnc_has_job_locked(vs);
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vnc_unlock_queue(queue);
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void vnc_jobs_clear(VncState *vs)
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vnc_lock_queue(queue);
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QTAILQ_FOREACH_SAFE(job, &queue->jobs, next, tmp) {
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if (job->vs == vs || !vs) {
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QTAILQ_REMOVE(&queue->jobs, job, next);
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vnc_unlock_queue(queue);
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void vnc_jobs_join(VncState *vs)
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vnc_lock_queue(queue);
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while (vnc_has_job_locked(vs)) {
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qemu_cond_wait(&queue->cond, &queue->mutex);
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vnc_unlock_queue(queue);
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* Copy data for local use
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static void vnc_async_encoding_start(VncState *orig, VncState *local)
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local->vnc_encoding = orig->vnc_encoding;
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local->features = orig->features;
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local->ds = orig->ds;
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local->vd = orig->vd;
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local->lossy_rect = orig->lossy_rect;
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local->write_pixels = orig->write_pixels;
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local->clientds = orig->clientds;
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local->tight = orig->tight;
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local->zlib = orig->zlib;
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local->hextile = orig->hextile;
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local->zrle = orig->zrle;
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local->output = queue->buffer;
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local->csock = -1; /* Don't do any network work on this thread */
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buffer_reset(&local->output);
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static void vnc_async_encoding_end(VncState *orig, VncState *local)
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orig->tight = local->tight;
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orig->zlib = local->zlib;
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orig->hextile = local->hextile;
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orig->zrle = local->zrle;
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orig->lossy_rect = local->lossy_rect;
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queue->buffer = local->output;
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static int vnc_worker_thread_loop(VncJobQueue *queue)
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VncRectEntry *entry, *tmp;
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vnc_lock_queue(queue);
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while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
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qemu_cond_wait(&queue->cond, &queue->mutex);
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/* Here job can only be NULL if queue->exit is true */
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job = QTAILQ_FIRST(&queue->jobs);
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vnc_unlock_queue(queue);
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vnc_lock_output(job->vs);
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if (job->vs->csock == -1 || job->vs->abort == true) {
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vnc_unlock_output(job->vs);
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/* Make a local copy of vs and switch output buffers */
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vnc_async_encoding_start(job->vs, &vs);
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/* Start sending rectangles */
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vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
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vnc_write_u8(&vs, 0);
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saved_offset = vs.output.offset;
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vnc_write_u16(&vs, 0);
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vnc_lock_display(job->vs->vd);
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QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
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if (job->vs->csock == -1) {
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vnc_unlock_display(job->vs->vd);
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/* output mutex must be locked before going to
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vnc_lock_output(job->vs);
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n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
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entry->rect.w, entry->rect.h);
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vnc_unlock_display(job->vs->vd);
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/* Put n_rectangles at the beginning of the message */
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vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
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vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
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/* Switch back buffers */
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vnc_lock_output(job->vs);
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if (job->vs->csock == -1) {
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vnc_write(job->vs, vs.output.buffer, vs.output.offset);
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/* Copy persistent encoding data */
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vnc_async_encoding_end(job->vs, &vs);
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flush = (job->vs->csock != -1 && job->vs->abort != true);
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vnc_unlock_output(job->vs);
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vnc_lock_queue(queue);
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QTAILQ_REMOVE(&queue->jobs, job, next);
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vnc_unlock_queue(queue);
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qemu_cond_broadcast(&queue->cond);
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static VncJobQueue *vnc_queue_init(void)
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VncJobQueue *queue = g_malloc0(sizeof(VncJobQueue));
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qemu_cond_init(&queue->cond);
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qemu_mutex_init(&queue->mutex);
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QTAILQ_INIT(&queue->jobs);
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static void vnc_queue_clear(VncJobQueue *q)
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qemu_cond_destroy(&queue->cond);
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qemu_mutex_destroy(&queue->mutex);
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buffer_free(&queue->buffer);
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queue = NULL; /* Unset global queue */
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static void *vnc_worker_thread(void *arg)
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VncJobQueue *queue = arg;
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qemu_thread_get_self(&queue->thread);
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while (!vnc_worker_thread_loop(queue)) ;
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vnc_queue_clear(queue);
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void vnc_start_worker_thread(void)
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if (vnc_worker_thread_running())
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q = vnc_queue_init();
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qemu_thread_create(&q->thread, vnc_worker_thread, q);
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queue = q; /* Set global queue */
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bool vnc_worker_thread_running(void)
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return queue; /* Check global queue */
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void vnc_stop_worker_thread(void)
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if (!vnc_worker_thread_running())
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/* Remove all jobs and wake up the thread */
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vnc_lock_queue(queue);
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vnc_unlock_queue(queue);
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vnc_jobs_clear(NULL);
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qemu_cond_broadcast(&queue->cond);