virtio-serial: avoid crash when port has no name
[qemu.git] / main-loop.c
1 /*
2 * QEMU System Emulator
3 *
4 * Copyright (c) 2003-2008 Fabrice Bellard
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25 #include "qemu-common.h"
26 #include "qemu/timer.h"
27 #include "qemu/sockets.h" // struct in_addr needed for libslirp.h
28 #include "sysemu/qtest.h"
29 #include "slirp/libslirp.h"
30 #include "qemu/main-loop.h"
31 #include "block/aio.h"
32
33 #ifndef _WIN32
34
35 #include "qemu/compatfd.h"
36
37 /* If we have signalfd, we mask out the signals we want to handle and then
38 * use signalfd to listen for them. We rely on whatever the current signal
39 * handler is to dispatch the signals when we receive them.
40 */
41 static void sigfd_handler(void *opaque)
42 {
43 int fd = (intptr_t)opaque;
44 struct qemu_signalfd_siginfo info;
45 struct sigaction action;
46 ssize_t len;
47
48 while (1) {
49 do {
50 len = read(fd, &info, sizeof(info));
51 } while (len == -1 && errno == EINTR);
52
53 if (len == -1 && errno == EAGAIN) {
54 break;
55 }
56
57 if (len != sizeof(info)) {
58 printf("read from sigfd returned %zd: %m\n", len);
59 return;
60 }
61
62 sigaction(info.ssi_signo, NULL, &action);
63 if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction) {
64 action.sa_sigaction(info.ssi_signo,
65 (siginfo_t *)&info, NULL);
66 } else if (action.sa_handler) {
67 action.sa_handler(info.ssi_signo);
68 }
69 }
70 }
71
72 static int qemu_signal_init(void)
73 {
74 int sigfd;
75 sigset_t set;
76
77 /*
78 * SIG_IPI must be blocked in the main thread and must not be caught
79 * by sigwait() in the signal thread. Otherwise, the cpu thread will
80 * not catch it reliably.
81 */
82 sigemptyset(&set);
83 sigaddset(&set, SIG_IPI);
84 sigaddset(&set, SIGIO);
85 sigaddset(&set, SIGALRM);
86 sigaddset(&set, SIGBUS);
87 /* SIGINT cannot be handled via signalfd, so that ^C can be used
88 * to interrupt QEMU when it is being run under gdb. SIGHUP and
89 * SIGTERM are also handled asynchronously, even though it is not
90 * strictly necessary, because they use the same handler as SIGINT.
91 */
92 pthread_sigmask(SIG_BLOCK, &set, NULL);
93
94 sigdelset(&set, SIG_IPI);
95 sigfd = qemu_signalfd(&set);
96 if (sigfd == -1) {
97 fprintf(stderr, "failed to create signalfd\n");
98 return -errno;
99 }
100
101 fcntl_setfl(sigfd, O_NONBLOCK);
102
103 qemu_set_fd_handler2(sigfd, NULL, sigfd_handler, NULL,
104 (void *)(intptr_t)sigfd);
105
106 return 0;
107 }
108
109 #else /* _WIN32 */
110
111 static int qemu_signal_init(void)
112 {
113 return 0;
114 }
115 #endif
116
117 static AioContext *qemu_aio_context;
118
119 AioContext *qemu_get_aio_context(void)
120 {
121 return qemu_aio_context;
122 }
123
124 void qemu_notify_event(void)
125 {
126 if (!qemu_aio_context) {
127 return;
128 }
129 aio_notify(qemu_aio_context);
130 }
131
132 static GArray *gpollfds;
133
134 int qemu_init_main_loop(Error **errp)
135 {
136 int ret;
137 GSource *src;
138 Error *local_error = NULL;
139
140 init_clocks();
141
142 ret = qemu_signal_init();
143 if (ret) {
144 return ret;
145 }
146
147 qemu_aio_context = aio_context_new(&local_error);
148 if (!qemu_aio_context) {
149 error_propagate(errp, local_error);
150 return -EMFILE;
151 }
152 gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
153 src = aio_get_g_source(qemu_aio_context);
154 g_source_attach(src, NULL);
155 g_source_unref(src);
156 return 0;
157 }
158
159 static int max_priority;
160
161 #ifndef _WIN32
162 static int glib_pollfds_idx;
163 static int glib_n_poll_fds;
164
165 static void glib_pollfds_fill(int64_t *cur_timeout)
166 {
167 GMainContext *context = g_main_context_default();
168 int timeout = 0;
169 int64_t timeout_ns;
170 int n;
171
172 g_main_context_prepare(context, &max_priority);
173
174 glib_pollfds_idx = gpollfds->len;
175 n = glib_n_poll_fds;
176 do {
177 GPollFD *pfds;
178 glib_n_poll_fds = n;
179 g_array_set_size(gpollfds, glib_pollfds_idx + glib_n_poll_fds);
180 pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
181 n = g_main_context_query(context, max_priority, &timeout, pfds,
182 glib_n_poll_fds);
183 } while (n != glib_n_poll_fds);
184
185 if (timeout < 0) {
186 timeout_ns = -1;
187 } else {
188 timeout_ns = (int64_t)timeout * (int64_t)SCALE_MS;
189 }
190
191 *cur_timeout = qemu_soonest_timeout(timeout_ns, *cur_timeout);
192 }
193
194 static void glib_pollfds_poll(void)
195 {
196 GMainContext *context = g_main_context_default();
197 GPollFD *pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
198
199 if (g_main_context_check(context, max_priority, pfds, glib_n_poll_fds)) {
200 g_main_context_dispatch(context);
201 }
202 }
203
204 #define MAX_MAIN_LOOP_SPIN (1000)
205
206 static int os_host_main_loop_wait(int64_t timeout)
207 {
208 int ret;
209 static int spin_counter;
210
211 glib_pollfds_fill(&timeout);
212
213 /* If the I/O thread is very busy or we are incorrectly busy waiting in
214 * the I/O thread, this can lead to starvation of the BQL such that the
215 * VCPU threads never run. To make sure we can detect the later case,
216 * print a message to the screen. If we run into this condition, create
217 * a fake timeout in order to give the VCPU threads a chance to run.
218 */
219 if (!timeout && (spin_counter > MAX_MAIN_LOOP_SPIN)) {
220 static bool notified;
221
222 if (!notified && !qtest_enabled()) {
223 fprintf(stderr,
224 "main-loop: WARNING: I/O thread spun for %d iterations\n",
225 MAX_MAIN_LOOP_SPIN);
226 notified = true;
227 }
228
229 timeout = SCALE_MS;
230 }
231
232 if (timeout) {
233 spin_counter = 0;
234 qemu_mutex_unlock_iothread();
235 } else {
236 spin_counter++;
237 }
238
239 ret = qemu_poll_ns((GPollFD *)gpollfds->data, gpollfds->len, timeout);
240
241 if (timeout) {
242 qemu_mutex_lock_iothread();
243 }
244
245 glib_pollfds_poll();
246 return ret;
247 }
248 #else
249 /***********************************************************/
250 /* Polling handling */
251
252 typedef struct PollingEntry {
253 PollingFunc *func;
254 void *opaque;
255 struct PollingEntry *next;
256 } PollingEntry;
257
258 static PollingEntry *first_polling_entry;
259
260 int qemu_add_polling_cb(PollingFunc *func, void *opaque)
261 {
262 PollingEntry **ppe, *pe;
263 pe = g_malloc0(sizeof(PollingEntry));
264 pe->func = func;
265 pe->opaque = opaque;
266 for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
267 *ppe = pe;
268 return 0;
269 }
270
271 void qemu_del_polling_cb(PollingFunc *func, void *opaque)
272 {
273 PollingEntry **ppe, *pe;
274 for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
275 pe = *ppe;
276 if (pe->func == func && pe->opaque == opaque) {
277 *ppe = pe->next;
278 g_free(pe);
279 break;
280 }
281 }
282 }
283
284 /***********************************************************/
285 /* Wait objects support */
286 typedef struct WaitObjects {
287 int num;
288 int revents[MAXIMUM_WAIT_OBJECTS + 1];
289 HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
290 WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
291 void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
292 } WaitObjects;
293
294 static WaitObjects wait_objects = {0};
295
296 int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
297 {
298 WaitObjects *w = &wait_objects;
299 if (w->num >= MAXIMUM_WAIT_OBJECTS) {
300 return -1;
301 }
302 w->events[w->num] = handle;
303 w->func[w->num] = func;
304 w->opaque[w->num] = opaque;
305 w->revents[w->num] = 0;
306 w->num++;
307 return 0;
308 }
309
310 void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
311 {
312 int i, found;
313 WaitObjects *w = &wait_objects;
314
315 found = 0;
316 for (i = 0; i < w->num; i++) {
317 if (w->events[i] == handle) {
318 found = 1;
319 }
320 if (found) {
321 w->events[i] = w->events[i + 1];
322 w->func[i] = w->func[i + 1];
323 w->opaque[i] = w->opaque[i + 1];
324 w->revents[i] = w->revents[i + 1];
325 }
326 }
327 if (found) {
328 w->num--;
329 }
330 }
331
332 void qemu_fd_register(int fd)
333 {
334 WSAEventSelect(fd, event_notifier_get_handle(&qemu_aio_context->notifier),
335 FD_READ | FD_ACCEPT | FD_CLOSE |
336 FD_CONNECT | FD_WRITE | FD_OOB);
337 }
338
339 static int pollfds_fill(GArray *pollfds, fd_set *rfds, fd_set *wfds,
340 fd_set *xfds)
341 {
342 int nfds = -1;
343 int i;
344
345 for (i = 0; i < pollfds->len; i++) {
346 GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
347 int fd = pfd->fd;
348 int events = pfd->events;
349 if (events & G_IO_IN) {
350 FD_SET(fd, rfds);
351 nfds = MAX(nfds, fd);
352 }
353 if (events & G_IO_OUT) {
354 FD_SET(fd, wfds);
355 nfds = MAX(nfds, fd);
356 }
357 if (events & G_IO_PRI) {
358 FD_SET(fd, xfds);
359 nfds = MAX(nfds, fd);
360 }
361 }
362 return nfds;
363 }
364
365 static void pollfds_poll(GArray *pollfds, int nfds, fd_set *rfds,
366 fd_set *wfds, fd_set *xfds)
367 {
368 int i;
369
370 for (i = 0; i < pollfds->len; i++) {
371 GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
372 int fd = pfd->fd;
373 int revents = 0;
374
375 if (FD_ISSET(fd, rfds)) {
376 revents |= G_IO_IN;
377 }
378 if (FD_ISSET(fd, wfds)) {
379 revents |= G_IO_OUT;
380 }
381 if (FD_ISSET(fd, xfds)) {
382 revents |= G_IO_PRI;
383 }
384 pfd->revents = revents & pfd->events;
385 }
386 }
387
388 static int os_host_main_loop_wait(int64_t timeout)
389 {
390 GMainContext *context = g_main_context_default();
391 GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
392 int select_ret = 0;
393 int g_poll_ret, ret, i, n_poll_fds;
394 PollingEntry *pe;
395 WaitObjects *w = &wait_objects;
396 gint poll_timeout;
397 int64_t poll_timeout_ns;
398 static struct timeval tv0;
399 fd_set rfds, wfds, xfds;
400 int nfds;
401
402 /* XXX: need to suppress polling by better using win32 events */
403 ret = 0;
404 for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
405 ret |= pe->func(pe->opaque);
406 }
407 if (ret != 0) {
408 return ret;
409 }
410
411 FD_ZERO(&rfds);
412 FD_ZERO(&wfds);
413 FD_ZERO(&xfds);
414 nfds = pollfds_fill(gpollfds, &rfds, &wfds, &xfds);
415 if (nfds >= 0) {
416 select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
417 if (select_ret != 0) {
418 timeout = 0;
419 }
420 if (select_ret > 0) {
421 pollfds_poll(gpollfds, nfds, &rfds, &wfds, &xfds);
422 }
423 }
424
425 g_main_context_prepare(context, &max_priority);
426 n_poll_fds = g_main_context_query(context, max_priority, &poll_timeout,
427 poll_fds, ARRAY_SIZE(poll_fds));
428 g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));
429
430 for (i = 0; i < w->num; i++) {
431 poll_fds[n_poll_fds + i].fd = (DWORD_PTR)w->events[i];
432 poll_fds[n_poll_fds + i].events = G_IO_IN;
433 }
434
435 if (poll_timeout < 0) {
436 poll_timeout_ns = -1;
437 } else {
438 poll_timeout_ns = (int64_t)poll_timeout * (int64_t)SCALE_MS;
439 }
440
441 poll_timeout_ns = qemu_soonest_timeout(poll_timeout_ns, timeout);
442
443 qemu_mutex_unlock_iothread();
444 g_poll_ret = qemu_poll_ns(poll_fds, n_poll_fds + w->num, poll_timeout_ns);
445
446 qemu_mutex_lock_iothread();
447 if (g_poll_ret > 0) {
448 for (i = 0; i < w->num; i++) {
449 w->revents[i] = poll_fds[n_poll_fds + i].revents;
450 }
451 for (i = 0; i < w->num; i++) {
452 if (w->revents[i] && w->func[i]) {
453 w->func[i](w->opaque[i]);
454 }
455 }
456 }
457
458 if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
459 g_main_context_dispatch(context);
460 }
461
462 return select_ret || g_poll_ret;
463 }
464 #endif
465
466 int main_loop_wait(int nonblocking)
467 {
468 int ret;
469 uint32_t timeout = UINT32_MAX;
470 int64_t timeout_ns;
471
472 if (nonblocking) {
473 timeout = 0;
474 }
475
476 /* poll any events */
477 g_array_set_size(gpollfds, 0); /* reset for new iteration */
478 /* XXX: separate device handlers from system ones */
479 #ifdef CONFIG_SLIRP
480 slirp_pollfds_fill(gpollfds, &timeout);
481 #endif
482 qemu_iohandler_fill(gpollfds);
483
484 if (timeout == UINT32_MAX) {
485 timeout_ns = -1;
486 } else {
487 timeout_ns = (uint64_t)timeout * (int64_t)(SCALE_MS);
488 }
489
490 timeout_ns = qemu_soonest_timeout(timeout_ns,
491 timerlistgroup_deadline_ns(
492 &main_loop_tlg));
493
494 ret = os_host_main_loop_wait(timeout_ns);
495 qemu_iohandler_poll(gpollfds, ret);
496 #ifdef CONFIG_SLIRP
497 slirp_pollfds_poll(gpollfds, (ret < 0));
498 #endif
499
500 qemu_clock_run_all_timers();
501
502 return ret;
503 }
504
505 /* Functions to operate on the main QEMU AioContext. */
506
507 QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
508 {
509 return aio_bh_new(qemu_aio_context, cb, opaque);
510 }