xref: /openbmc/qemu/ui/vnc-jobs.c (revision bdfca8a2)
1 /*
2  * QEMU VNC display driver
3  *
4  * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
5  * Copyright (C) 2006 Fabrice Bellard
6  * Copyright (C) 2009 Red Hat, Inc
7  * Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
8  *
9  * Permission is hereby granted, free of charge, to any person obtaining a copy
10  * of this software and associated documentation files (the "Software"), to deal
11  * in the Software without restriction, including without limitation the rights
12  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13  * copies of the Software, and to permit persons to whom the Software is
14  * furnished to do so, subject to the following conditions:
15  *
16  * The above copyright notice and this permission notice shall be included in
17  * all copies or substantial portions of the Software.
18  *
19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
22  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
25  * THE SOFTWARE.
26  */
27 
28 
29 #include "qemu/osdep.h"
30 #include "vnc.h"
31 #include "vnc-jobs.h"
32 #include "qemu/sockets.h"
33 #include "qemu/main-loop.h"
34 #include "block/aio.h"
35 #include "trace.h"
36 
37 /*
38  * Locking:
39  *
40  * There are three levels of locking:
41  * - jobs queue lock: for each operation on the queue (push, pop, isEmpty?)
42  * - VncDisplay global lock: mainly used for framebuffer updates to avoid
43  *                      screen corruption if the framebuffer is updated
44  *                      while the worker is doing something.
45  * - VncState::output lock: used to make sure the output buffer is not corrupted
46  *                          if two threads try to write on it at the same time
47  *
48  * While the VNC worker thread is working, the VncDisplay global lock is held
49  * to avoid screen corruption (this does not block vnc_refresh() because it
50  * uses trylock()) but the output lock is not held because the thread works on
51  * its own output buffer.
52  * When the encoding job is done, the worker thread will hold the output lock
53  * and copy its output buffer in vs->output.
54  */
55 
56 struct VncJobQueue {
57     QemuCond cond;
58     QemuMutex mutex;
59     QemuThread thread;
60     bool exit;
61     QTAILQ_HEAD(, VncJob) jobs;
62 };
63 
64 typedef struct VncJobQueue VncJobQueue;
65 
66 /*
67  * We use a single global queue, but most of the functions are
68  * already reentrant, so we can easily add more than one encoding thread
69  */
70 static VncJobQueue *queue;
71 
vnc_lock_queue(VncJobQueue * queue)72 static void vnc_lock_queue(VncJobQueue *queue)
73 {
74     qemu_mutex_lock(&queue->mutex);
75 }
76 
vnc_unlock_queue(VncJobQueue * queue)77 static void vnc_unlock_queue(VncJobQueue *queue)
78 {
79     qemu_mutex_unlock(&queue->mutex);
80 }
81 
vnc_job_new(VncState * vs)82 VncJob *vnc_job_new(VncState *vs)
83 {
84     VncJob *job = g_new0(VncJob, 1);
85 
86     assert(vs->magic == VNC_MAGIC);
87     job->vs = vs;
88     vnc_lock_queue(queue);
89     QLIST_INIT(&job->rectangles);
90     vnc_unlock_queue(queue);
91     return job;
92 }
93 
vnc_job_add_rect(VncJob * job,int x,int y,int w,int h)94 int vnc_job_add_rect(VncJob *job, int x, int y, int w, int h)
95 {
96     VncRectEntry *entry = g_new0(VncRectEntry, 1);
97 
98     trace_vnc_job_add_rect(job->vs, job, x, y, w, h);
99 
100     entry->rect.x = x;
101     entry->rect.y = y;
102     entry->rect.w = w;
103     entry->rect.h = h;
104 
105     vnc_lock_queue(queue);
106     QLIST_INSERT_HEAD(&job->rectangles, entry, next);
107     vnc_unlock_queue(queue);
108     return 1;
109 }
110 
vnc_job_push(VncJob * job)111 void vnc_job_push(VncJob *job)
112 {
113     vnc_lock_queue(queue);
114     if (queue->exit || QLIST_EMPTY(&job->rectangles)) {
115         g_free(job);
116     } else {
117         QTAILQ_INSERT_TAIL(&queue->jobs, job, next);
118         qemu_cond_broadcast(&queue->cond);
119     }
120     vnc_unlock_queue(queue);
121 }
122 
vnc_has_job_locked(VncState * vs)123 static bool vnc_has_job_locked(VncState *vs)
124 {
125     VncJob *job;
126 
127     QTAILQ_FOREACH(job, &queue->jobs, next) {
128         if (job->vs == vs || !vs) {
129             return true;
130         }
131     }
132     return false;
133 }
134 
vnc_jobs_join(VncState * vs)135 void vnc_jobs_join(VncState *vs)
136 {
137     vnc_lock_queue(queue);
138     while (vnc_has_job_locked(vs)) {
139         qemu_cond_wait(&queue->cond, &queue->mutex);
140     }
141     vnc_unlock_queue(queue);
142     vnc_jobs_consume_buffer(vs);
143 }
144 
vnc_jobs_consume_buffer(VncState * vs)145 void vnc_jobs_consume_buffer(VncState *vs)
146 {
147     bool flush;
148 
149     vnc_lock_output(vs);
150     if (vs->jobs_buffer.offset) {
151         if (vs->ioc != NULL && buffer_empty(&vs->output)) {
152             if (vs->ioc_tag) {
153                 g_source_remove(vs->ioc_tag);
154             }
155             if (vs->disconnecting == FALSE) {
156                 vs->ioc_tag = qio_channel_add_watch(
157                     vs->ioc, G_IO_IN | G_IO_HUP | G_IO_ERR | G_IO_OUT,
158                     vnc_client_io, vs, NULL);
159             }
160         }
161         buffer_move(&vs->output, &vs->jobs_buffer);
162 
163         if (vs->job_update == VNC_STATE_UPDATE_FORCE) {
164             vs->force_update_offset = vs->output.offset;
165         }
166         vs->job_update = VNC_STATE_UPDATE_NONE;
167     }
168     flush = vs->ioc != NULL && vs->abort != true;
169     vnc_unlock_output(vs);
170 
171     if (flush) {
172       vnc_flush(vs);
173     }
174 }
175 
176 /*
177  * Copy data for local use
178  */
vnc_async_encoding_start(VncState * orig,VncState * local)179 static void vnc_async_encoding_start(VncState *orig, VncState *local)
180 {
181     buffer_init(&local->output, "vnc-worker-output");
182     local->sioc = NULL; /* Don't do any network work on this thread */
183     local->ioc = NULL; /* Don't do any network work on this thread */
184 
185     local->vnc_encoding = orig->vnc_encoding;
186     local->features = orig->features;
187     local->vd = orig->vd;
188     local->lossy_rect = orig->lossy_rect;
189     local->write_pixels = orig->write_pixels;
190     local->client_pf = orig->client_pf;
191     local->client_be = orig->client_be;
192     local->tight = orig->tight;
193     local->zlib = orig->zlib;
194     local->hextile = orig->hextile;
195     local->zrle = orig->zrle;
196     local->client_width = orig->client_width;
197     local->client_height = orig->client_height;
198 }
199 
vnc_async_encoding_end(VncState * orig,VncState * local)200 static void vnc_async_encoding_end(VncState *orig, VncState *local)
201 {
202     buffer_free(&local->output);
203     orig->tight = local->tight;
204     orig->zlib = local->zlib;
205     orig->hextile = local->hextile;
206     orig->zrle = local->zrle;
207     orig->lossy_rect = local->lossy_rect;
208 }
209 
vnc_worker_clamp_rect(VncState * vs,VncJob * job,VncRect * rect)210 static bool vnc_worker_clamp_rect(VncState *vs, VncJob *job, VncRect *rect)
211 {
212     trace_vnc_job_clamp_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
213 
214     if (rect->x >= vs->client_width) {
215         goto discard;
216     }
217     rect->w = MIN(vs->client_width - rect->x, rect->w);
218     if (rect->w == 0) {
219         goto discard;
220     }
221 
222     if (rect->y >= vs->client_height) {
223         goto discard;
224     }
225     rect->h = MIN(vs->client_height - rect->y, rect->h);
226     if (rect->h == 0) {
227         goto discard;
228     }
229 
230     trace_vnc_job_clamped_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
231     return true;
232 
233  discard:
234     trace_vnc_job_discard_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
235     return false;
236 }
237 
vnc_worker_thread_loop(VncJobQueue * queue)238 static int vnc_worker_thread_loop(VncJobQueue *queue)
239 {
240     VncJob *job;
241     VncRectEntry *entry, *tmp;
242     VncState vs = {};
243     int n_rectangles;
244     int saved_offset;
245 
246     vnc_lock_queue(queue);
247     while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
248         qemu_cond_wait(&queue->cond, &queue->mutex);
249     }
250     /* Here job can only be NULL if queue->exit is true */
251     job = QTAILQ_FIRST(&queue->jobs);
252     vnc_unlock_queue(queue);
253 
254     if (queue->exit) {
255         return -1;
256     }
257 
258     assert(job->vs->magic == VNC_MAGIC);
259 
260     vnc_lock_output(job->vs);
261     if (job->vs->ioc == NULL || job->vs->abort == true) {
262         vnc_unlock_output(job->vs);
263         goto disconnected;
264     }
265     if (buffer_empty(&job->vs->output)) {
266         /*
267          * Looks like a NOP as it obviously moves no data.  But it
268          * moves the empty buffer, so we don't have to malloc a new
269          * one for vs.output
270          */
271         buffer_move_empty(&vs.output, &job->vs->output);
272     }
273     vnc_unlock_output(job->vs);
274 
275     /* Make a local copy of vs and switch output buffers */
276     vnc_async_encoding_start(job->vs, &vs);
277     vs.magic = VNC_MAGIC;
278 
279     /* Start sending rectangles */
280     n_rectangles = 0;
281     vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
282     vnc_write_u8(&vs, 0);
283     saved_offset = vs.output.offset;
284     vnc_write_u16(&vs, 0);
285 
286     vnc_lock_display(job->vs->vd);
287     QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
288         int n;
289 
290         if (job->vs->ioc == NULL) {
291             vnc_unlock_display(job->vs->vd);
292             /* Copy persistent encoding data */
293             vnc_async_encoding_end(job->vs, &vs);
294             goto disconnected;
295         }
296 
297         if (vnc_worker_clamp_rect(&vs, job, &entry->rect)) {
298             n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
299                                             entry->rect.w, entry->rect.h);
300 
301             if (n >= 0) {
302                 n_rectangles += n;
303             }
304         }
305         g_free(entry);
306     }
307     trace_vnc_job_nrects(&vs, job, n_rectangles);
308     vnc_unlock_display(job->vs->vd);
309 
310     /* Put n_rectangles at the beginning of the message */
311     vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
312     vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
313 
314     vnc_lock_output(job->vs);
315     if (job->vs->ioc != NULL) {
316         buffer_move(&job->vs->jobs_buffer, &vs.output);
317         /* Copy persistent encoding data */
318         vnc_async_encoding_end(job->vs, &vs);
319 
320         qemu_bh_schedule(job->vs->bh);
321     }  else {
322         buffer_reset(&vs.output);
323         /* Copy persistent encoding data */
324         vnc_async_encoding_end(job->vs, &vs);
325     }
326     vnc_unlock_output(job->vs);
327 
328 disconnected:
329     vnc_lock_queue(queue);
330     QTAILQ_REMOVE(&queue->jobs, job, next);
331     vnc_unlock_queue(queue);
332     qemu_cond_broadcast(&queue->cond);
333     g_free(job);
334     vs.magic = 0;
335     return 0;
336 }
337 
vnc_queue_init(void)338 static VncJobQueue *vnc_queue_init(void)
339 {
340     VncJobQueue *queue = g_new0(VncJobQueue, 1);
341 
342     qemu_cond_init(&queue->cond);
343     qemu_mutex_init(&queue->mutex);
344     QTAILQ_INIT(&queue->jobs);
345     return queue;
346 }
347 
vnc_queue_clear(VncJobQueue * q)348 static void vnc_queue_clear(VncJobQueue *q)
349 {
350     qemu_cond_destroy(&queue->cond);
351     qemu_mutex_destroy(&queue->mutex);
352     g_free(q);
353     queue = NULL; /* Unset global queue */
354 }
355 
vnc_worker_thread(void * arg)356 static void *vnc_worker_thread(void *arg)
357 {
358     VncJobQueue *queue = arg;
359 
360     qemu_thread_get_self(&queue->thread);
361 
362     while (!vnc_worker_thread_loop(queue)) ;
363     vnc_queue_clear(queue);
364     return NULL;
365 }
366 
vnc_worker_thread_running(void)367 static bool vnc_worker_thread_running(void)
368 {
369     return queue; /* Check global queue */
370 }
371 
vnc_start_worker_thread(void)372 void vnc_start_worker_thread(void)
373 {
374     VncJobQueue *q;
375 
376     if (vnc_worker_thread_running())
377         return;
378 
379     q = vnc_queue_init();
380     qemu_thread_create(&q->thread, "vnc_worker", vnc_worker_thread, q,
381                        QEMU_THREAD_DETACHED);
382     queue = q; /* Set global queue */
383 }
384