2 * event notifier support
4 * Copyright Red Hat, Inc. 2010
7 * Michael S. Tsirkin <mst@redhat.com>
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.
13 #include "qemu/osdep.h"
14 #include "qemu/cutils.h"
15 #include "qemu/event_notifier.h"
16 #include "qemu/main-loop.h"
19 #include <sys/eventfd.h>
24 * Initialize @e with existing file descriptor @fd.
25 * @fd must be a genuine eventfd object, emulation with pipe won't do.
27 void event_notifier_init_fd(EventNotifier *e, int fd)
31 e->initialized = true;
35 int event_notifier_init(EventNotifier *e, int active)
41 ret = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
47 e->rfd = e->wfd = ret;
49 if (errno != ENOSYS) {
52 if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) {
55 if (!g_unix_set_fd_nonblocking(fds[0], true, NULL)) {
59 if (!g_unix_set_fd_nonblocking(fds[1], true, NULL)) {
66 e->initialized = true;
68 event_notifier_set(e);
78 void event_notifier_cleanup(EventNotifier *e)
80 if (!e->initialized) {
84 if (e->rfd != e->wfd) {
91 e->initialized = false;
94 int event_notifier_get_fd(const EventNotifier *e)
99 int event_notifier_get_wfd(const EventNotifier *e)
104 int event_notifier_set(EventNotifier *e)
106 static const uint64_t value = 1;
109 if (!e->initialized) {
114 ret = write(e->wfd, &value, sizeof(value));
115 } while (ret < 0 && errno == EINTR);
117 /* EAGAIN is fine, a read must be pending. */
118 if (ret < 0 && errno != EAGAIN) {
124 int event_notifier_test_and_clear(EventNotifier *e)
130 if (!e->initialized) {
134 /* Drain the notify pipe. For eventfd, only 8 bytes will be read. */
137 len = read(e->rfd, buffer, sizeof(buffer));
139 } while ((len == -1 && errno == EINTR) || len == sizeof(buffer));