File:  [Qemu by Fabrice Bellard] / qemu / main-loop.c
Revision 1.1.1.1 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 19:17:24 2018 UTC (3 years, 1 month ago) by root
Branches: qemu, MAIN
CVS tags: qemu1001, HEAD
qemu 1.0.1

    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 "slirp/slirp.h"
   28: #include "main-loop.h"
   29: 
   30: #ifndef _WIN32
   31: 
   32: #include "compatfd.h"
   33: 
   34: static int io_thread_fd = -1;
   35: 
   36: void qemu_notify_event(void)
   37: {
   38:     /* Write 8 bytes to be compatible with eventfd.  */
   39:     static const uint64_t val = 1;
   40:     ssize_t ret;
   41: 
   42:     if (io_thread_fd == -1) {
   43:         return;
   44:     }
   45:     do {
   46:         ret = write(io_thread_fd, &val, sizeof(val));
   47:     } while (ret < 0 && errno == EINTR);
   48: 
   49:     /* EAGAIN is fine, a read must be pending.  */
   50:     if (ret < 0 && errno != EAGAIN) {
   51:         fprintf(stderr, "qemu_notify_event: write() failed: %s\n",
   52:                 strerror(errno));
   53:         exit(1);
   54:     }
   55: }
   56: 
   57: static void qemu_event_read(void *opaque)
   58: {
   59:     int fd = (intptr_t)opaque;
   60:     ssize_t len;
   61:     char buffer[512];
   62: 
   63:     /* Drain the notify pipe.  For eventfd, only 8 bytes will be read.  */
   64:     do {
   65:         len = read(fd, buffer, sizeof(buffer));
   66:     } while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
   67: }
   68: 
   69: static int qemu_event_init(void)
   70: {
   71:     int err;
   72:     int fds[2];
   73: 
   74:     err = qemu_eventfd(fds);
   75:     if (err == -1) {
   76:         return -errno;
   77:     }
   78:     err = fcntl_setfl(fds[0], O_NONBLOCK);
   79:     if (err < 0) {
   80:         goto fail;
   81:     }
   82:     err = fcntl_setfl(fds[1], O_NONBLOCK);
   83:     if (err < 0) {
   84:         goto fail;
   85:     }
   86:     qemu_set_fd_handler2(fds[0], NULL, qemu_event_read, NULL,
   87:                          (void *)(intptr_t)fds[0]);
   88: 
   89:     io_thread_fd = fds[1];
   90:     return 0;
   91: 
   92: fail:
   93:     close(fds[0]);
   94:     close(fds[1]);
   95:     return err;
   96: }
   97: 
   98: /* If we have signalfd, we mask out the signals we want to handle and then
   99:  * use signalfd to listen for them.  We rely on whatever the current signal
  100:  * handler is to dispatch the signals when we receive them.
  101:  */
  102: static void sigfd_handler(void *opaque)
  103: {
  104:     int fd = (intptr_t)opaque;
  105:     struct qemu_signalfd_siginfo info;
  106:     struct sigaction action;
  107:     ssize_t len;
  108: 
  109:     while (1) {
  110:         do {
  111:             len = read(fd, &info, sizeof(info));
  112:         } while (len == -1 && errno == EINTR);
  113: 
  114:         if (len == -1 && errno == EAGAIN) {
  115:             break;
  116:         }
  117: 
  118:         if (len != sizeof(info)) {
  119:             printf("read from sigfd returned %zd: %m\n", len);
  120:             return;
  121:         }
  122: 
  123:         sigaction(info.ssi_signo, NULL, &action);
  124:         if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction) {
  125:             action.sa_sigaction(info.ssi_signo,
  126:                                 (siginfo_t *)&info, NULL);
  127:         } else if (action.sa_handler) {
  128:             action.sa_handler(info.ssi_signo);
  129:         }
  130:     }
  131: }
  132: 
  133: static int qemu_signal_init(void)
  134: {
  135:     int sigfd;
  136:     sigset_t set;
  137: 
  138:     /*
  139:      * SIG_IPI must be blocked in the main thread and must not be caught
  140:      * by sigwait() in the signal thread. Otherwise, the cpu thread will
  141:      * not catch it reliably.
  142:      */
  143:     sigemptyset(&set);
  144:     sigaddset(&set, SIG_IPI);
  145:     pthread_sigmask(SIG_BLOCK, &set, NULL);
  146: 
  147:     sigemptyset(&set);
  148:     sigaddset(&set, SIGIO);
  149:     sigaddset(&set, SIGALRM);
  150:     sigaddset(&set, SIGBUS);
  151:     pthread_sigmask(SIG_BLOCK, &set, NULL);
  152: 
  153:     sigfd = qemu_signalfd(&set);
  154:     if (sigfd == -1) {
  155:         fprintf(stderr, "failed to create signalfd\n");
  156:         return -errno;
  157:     }
  158: 
  159:     fcntl_setfl(sigfd, O_NONBLOCK);
  160: 
  161:     qemu_set_fd_handler2(sigfd, NULL, sigfd_handler, NULL,
  162:                          (void *)(intptr_t)sigfd);
  163: 
  164:     return 0;
  165: }
  166: 
  167: #else /* _WIN32 */
  168: 
  169: HANDLE qemu_event_handle;
  170: 
  171: static void dummy_event_handler(void *opaque)
  172: {
  173: }
  174: 
  175: static int qemu_event_init(void)
  176: {
  177:     qemu_event_handle = CreateEvent(NULL, FALSE, FALSE, NULL);
  178:     if (!qemu_event_handle) {
  179:         fprintf(stderr, "Failed CreateEvent: %ld\n", GetLastError());
  180:         return -1;
  181:     }
  182:     qemu_add_wait_object(qemu_event_handle, dummy_event_handler, NULL);
  183:     return 0;
  184: }
  185: 
  186: void qemu_notify_event(void)
  187: {
  188:     if (!SetEvent(qemu_event_handle)) {
  189:         fprintf(stderr, "qemu_notify_event: SetEvent failed: %ld\n",
  190:                 GetLastError());
  191:         exit(1);
  192:     }
  193: }
  194: 
  195: static int qemu_signal_init(void)
  196: {
  197:     return 0;
  198: }
  199: #endif
  200: 
  201: int qemu_init_main_loop(void)
  202: {
  203:     int ret;
  204: 
  205:     qemu_mutex_lock_iothread();
  206:     ret = qemu_signal_init();
  207:     if (ret) {
  208:         return ret;
  209:     }
  210: 
  211:     /* Note eventfd must be drained before signalfd handlers run */
  212:     ret = qemu_event_init();
  213:     if (ret) {
  214:         return ret;
  215:     }
  216: 
  217:     return 0;
  218: }
  219: 
  220: 
  221: static GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
  222: static int n_poll_fds;
  223: static int max_priority;
  224: 
  225: static void glib_select_fill(int *max_fd, fd_set *rfds, fd_set *wfds,
  226:                              fd_set *xfds, struct timeval *tv)
  227: {
  228:     GMainContext *context = g_main_context_default();
  229:     int i;
  230:     int timeout = 0, cur_timeout;
  231: 
  232:     g_main_context_prepare(context, &max_priority);
  233: 
  234:     n_poll_fds = g_main_context_query(context, max_priority, &timeout,
  235:                                       poll_fds, ARRAY_SIZE(poll_fds));
  236:     g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));
  237: 
  238:     for (i = 0; i < n_poll_fds; i++) {
  239:         GPollFD *p = &poll_fds[i];
  240: 
  241:         if ((p->events & G_IO_IN)) {
  242:             FD_SET(p->fd, rfds);
  243:             *max_fd = MAX(*max_fd, p->fd);
  244:         }
  245:         if ((p->events & G_IO_OUT)) {
  246:             FD_SET(p->fd, wfds);
  247:             *max_fd = MAX(*max_fd, p->fd);
  248:         }
  249:         if ((p->events & G_IO_ERR)) {
  250:             FD_SET(p->fd, xfds);
  251:             *max_fd = MAX(*max_fd, p->fd);
  252:         }
  253:     }
  254: 
  255:     cur_timeout = (tv->tv_sec * 1000) + ((tv->tv_usec + 500) / 1000);
  256:     if (timeout >= 0 && timeout < cur_timeout) {
  257:         tv->tv_sec = timeout / 1000;
  258:         tv->tv_usec = (timeout % 1000) * 1000;
  259:     }
  260: }
  261: 
  262: static void glib_select_poll(fd_set *rfds, fd_set *wfds, fd_set *xfds,
  263:                              bool err)
  264: {
  265:     GMainContext *context = g_main_context_default();
  266: 
  267:     if (!err) {
  268:         int i;
  269: 
  270:         for (i = 0; i < n_poll_fds; i++) {
  271:             GPollFD *p = &poll_fds[i];
  272: 
  273:             if ((p->events & G_IO_IN) && FD_ISSET(p->fd, rfds)) {
  274:                 p->revents |= G_IO_IN;
  275:             }
  276:             if ((p->events & G_IO_OUT) && FD_ISSET(p->fd, wfds)) {
  277:                 p->revents |= G_IO_OUT;
  278:             }
  279:             if ((p->events & G_IO_ERR) && FD_ISSET(p->fd, xfds)) {
  280:                 p->revents |= G_IO_ERR;
  281:             }
  282:         }
  283:     }
  284: 
  285:     if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
  286:         g_main_context_dispatch(context);
  287:     }
  288: }
  289: 
  290: #ifdef _WIN32
  291: /***********************************************************/
  292: /* Polling handling */
  293: 
  294: typedef struct PollingEntry {
  295:     PollingFunc *func;
  296:     void *opaque;
  297:     struct PollingEntry *next;
  298: } PollingEntry;
  299: 
  300: static PollingEntry *first_polling_entry;
  301: 
  302: int qemu_add_polling_cb(PollingFunc *func, void *opaque)
  303: {
  304:     PollingEntry **ppe, *pe;
  305:     pe = g_malloc0(sizeof(PollingEntry));
  306:     pe->func = func;
  307:     pe->opaque = opaque;
  308:     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
  309:     *ppe = pe;
  310:     return 0;
  311: }
  312: 
  313: void qemu_del_polling_cb(PollingFunc *func, void *opaque)
  314: {
  315:     PollingEntry **ppe, *pe;
  316:     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
  317:         pe = *ppe;
  318:         if (pe->func == func && pe->opaque == opaque) {
  319:             *ppe = pe->next;
  320:             g_free(pe);
  321:             break;
  322:         }
  323:     }
  324: }
  325: 
  326: /***********************************************************/
  327: /* Wait objects support */
  328: typedef struct WaitObjects {
  329:     int num;
  330:     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
  331:     WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
  332:     void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
  333: } WaitObjects;
  334: 
  335: static WaitObjects wait_objects = {0};
  336: 
  337: int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
  338: {
  339:     WaitObjects *w = &wait_objects;
  340:     if (w->num >= MAXIMUM_WAIT_OBJECTS) {
  341:         return -1;
  342:     }
  343:     w->events[w->num] = handle;
  344:     w->func[w->num] = func;
  345:     w->opaque[w->num] = opaque;
  346:     w->num++;
  347:     return 0;
  348: }
  349: 
  350: void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
  351: {
  352:     int i, found;
  353:     WaitObjects *w = &wait_objects;
  354: 
  355:     found = 0;
  356:     for (i = 0; i < w->num; i++) {
  357:         if (w->events[i] == handle) {
  358:             found = 1;
  359:         }
  360:         if (found) {
  361:             w->events[i] = w->events[i + 1];
  362:             w->func[i] = w->func[i + 1];
  363:             w->opaque[i] = w->opaque[i + 1];
  364:         }
  365:     }
  366:     if (found) {
  367:         w->num--;
  368:     }
  369: }
  370: 
  371: static void os_host_main_loop_wait(int *timeout)
  372: {
  373:     int ret, ret2, i;
  374:     PollingEntry *pe;
  375: 
  376:     /* XXX: need to suppress polling by better using win32 events */
  377:     ret = 0;
  378:     for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
  379:         ret |= pe->func(pe->opaque);
  380:     }
  381:     if (ret == 0) {
  382:         int err;
  383:         WaitObjects *w = &wait_objects;
  384: 
  385:         qemu_mutex_unlock_iothread();
  386:         ret = WaitForMultipleObjects(w->num, w->events, FALSE, *timeout);
  387:         qemu_mutex_lock_iothread();
  388:         if (WAIT_OBJECT_0 + 0 <= ret && ret <= WAIT_OBJECT_0 + w->num - 1) {
  389:             if (w->func[ret - WAIT_OBJECT_0]) {
  390:                 w->func[ret - WAIT_OBJECT_0](w->opaque[ret - WAIT_OBJECT_0]);
  391:             }
  392: 
  393:             /* Check for additional signaled events */
  394:             for (i = (ret - WAIT_OBJECT_0 + 1); i < w->num; i++) {
  395:                 /* Check if event is signaled */
  396:                 ret2 = WaitForSingleObject(w->events[i], 0);
  397:                 if (ret2 == WAIT_OBJECT_0) {
  398:                     if (w->func[i]) {
  399:                         w->func[i](w->opaque[i]);
  400:                     }
  401:                 } else if (ret2 != WAIT_TIMEOUT) {
  402:                     err = GetLastError();
  403:                     fprintf(stderr, "WaitForSingleObject error %d %d\n", i, err);
  404:                 }
  405:             }
  406:         } else if (ret != WAIT_TIMEOUT) {
  407:             err = GetLastError();
  408:             fprintf(stderr, "WaitForMultipleObjects error %d %d\n", ret, err);
  409:         }
  410:     }
  411: 
  412:     *timeout = 0;
  413: }
  414: #else
  415: static inline void os_host_main_loop_wait(int *timeout)
  416: {
  417: }
  418: #endif
  419: 
  420: int main_loop_wait(int nonblocking)
  421: {
  422:     fd_set rfds, wfds, xfds;
  423:     int ret, nfds;
  424:     struct timeval tv;
  425:     int timeout;
  426: 
  427:     if (nonblocking) {
  428:         timeout = 0;
  429:     } else {
  430:         timeout = qemu_calculate_timeout();
  431:         qemu_bh_update_timeout(&timeout);
  432:     }
  433: 
  434:     os_host_main_loop_wait(&timeout);
  435: 
  436:     tv.tv_sec = timeout / 1000;
  437:     tv.tv_usec = (timeout % 1000) * 1000;
  438: 
  439:     /* poll any events */
  440:     /* XXX: separate device handlers from system ones */
  441:     nfds = -1;
  442:     FD_ZERO(&rfds);
  443:     FD_ZERO(&wfds);
  444:     FD_ZERO(&xfds);
  445: 
  446: #ifdef CONFIG_SLIRP
  447:     slirp_select_fill(&nfds, &rfds, &wfds, &xfds);
  448: #endif
  449:     qemu_iohandler_fill(&nfds, &rfds, &wfds, &xfds);
  450:     glib_select_fill(&nfds, &rfds, &wfds, &xfds, &tv);
  451: 
  452:     if (timeout > 0) {
  453:         qemu_mutex_unlock_iothread();
  454:     }
  455: 
  456:     ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv);
  457: 
  458:     if (timeout > 0) {
  459:         qemu_mutex_lock_iothread();
  460:     }
  461: 
  462:     glib_select_poll(&rfds, &wfds, &xfds, (ret < 0));
  463:     qemu_iohandler_poll(&rfds, &wfds, &xfds, ret);
  464: #ifdef CONFIG_SLIRP
  465:     slirp_select_poll(&rfds, &wfds, &xfds, (ret < 0));
  466: #endif
  467: 
  468:     qemu_run_all_timers();
  469: 
  470:     /* Check bottom-halves last in case any of the earlier events triggered
  471:        them.  */
  472:     qemu_bh_poll();
  473: 
  474:     return ret;
  475: }

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