143 lines
2.7 KiB
C
143 lines
2.7 KiB
C
/*
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* event notifier support
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*
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* Copyright Red Hat, Inc. 2010
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*
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* Authors:
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* Michael S. Tsirkin <mst@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "qemu/cutils.h"
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#include "qemu/event_notifier.h"
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#include "qemu/main-loop.h"
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#ifdef CONFIG_EVENTFD
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#include <sys/eventfd.h>
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#endif
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#ifdef CONFIG_EVENTFD
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/*
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* Initialize @e with existing file descriptor @fd.
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* @fd must be a genuine eventfd object, emulation with pipe won't do.
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*/
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void event_notifier_init_fd(EventNotifier *e, int fd)
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{
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e->rfd = fd;
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e->wfd = fd;
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e->initialized = true;
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}
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#endif
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int event_notifier_init(EventNotifier *e, int active)
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{
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int fds[2];
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int ret;
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#ifdef CONFIG_EVENTFD
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ret = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
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#else
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ret = -1;
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errno = ENOSYS;
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#endif
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if (ret >= 0) {
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e->rfd = e->wfd = ret;
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} else {
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if (errno != ENOSYS) {
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return -errno;
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}
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if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) {
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return -errno;
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}
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if (!g_unix_set_fd_nonblocking(fds[0], true, NULL)) {
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ret = -errno;
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goto fail;
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}
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if (!g_unix_set_fd_nonblocking(fds[1], true, NULL)) {
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ret = -errno;
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goto fail;
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}
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e->rfd = fds[0];
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e->wfd = fds[1];
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}
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e->initialized = true;
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if (active) {
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event_notifier_set(e);
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}
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return 0;
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fail:
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close(fds[0]);
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close(fds[1]);
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return ret;
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}
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void event_notifier_cleanup(EventNotifier *e)
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{
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if (!e->initialized) {
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return;
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}
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if (e->rfd != e->wfd) {
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close(e->rfd);
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}
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e->rfd = -1;
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close(e->wfd);
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e->wfd = -1;
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e->initialized = false;
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}
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int event_notifier_get_fd(const EventNotifier *e)
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{
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return e->rfd;
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}
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int event_notifier_get_wfd(const EventNotifier *e)
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{
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return e->wfd;
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}
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int event_notifier_set(EventNotifier *e)
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{
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static const uint64_t value = 1;
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ssize_t ret;
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if (!e->initialized) {
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return -1;
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}
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do {
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ret = write(e->wfd, &value, sizeof(value));
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} while (ret < 0 && errno == EINTR);
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/* EAGAIN is fine, a read must be pending. */
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if (ret < 0 && errno != EAGAIN) {
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return -errno;
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}
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return 0;
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}
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int event_notifier_test_and_clear(EventNotifier *e)
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{
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int value;
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ssize_t len;
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char buffer[512];
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if (!e->initialized) {
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return 0;
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}
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/* Drain the notify pipe. For eventfd, only 8 bytes will be read. */
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value = 0;
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do {
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len = read(e->rfd, buffer, sizeof(buffer));
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value |= (len > 0);
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} while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
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return value;
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}
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