101 lines
2.6 KiB
C
101 lines
2.6 KiB
C
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/*
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* Event loop with file descriptor polling
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*
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* Copyright 2012 IBM, Corp.
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* Copyright 2012 Red Hat, Inc. and/or its affiliates
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@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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*/
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#include <sys/epoll.h>
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#include "hw/dataplane/event-poll.h"
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/* Add an event notifier and its callback for polling */
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void event_poll_add(EventPoll *poll, EventHandler *handler,
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EventNotifier *notifier, EventCallback *callback)
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{
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struct epoll_event event = {
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.events = EPOLLIN,
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.data.ptr = handler,
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};
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handler->notifier = notifier;
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handler->callback = callback;
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if (epoll_ctl(poll->epoll_fd, EPOLL_CTL_ADD,
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event_notifier_get_fd(notifier), &event) != 0) {
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fprintf(stderr, "failed to add event handler to epoll: %m\n");
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exit(1);
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}
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}
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/* Event callback for stopping event_poll() */
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static void handle_stop(EventHandler *handler)
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{
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/* Do nothing */
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}
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void event_poll_init(EventPoll *poll)
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{
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/* Create epoll file descriptor */
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poll->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
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if (poll->epoll_fd < 0) {
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fprintf(stderr, "epoll_create1 failed: %m\n");
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exit(1);
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}
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/* Set up stop notifier */
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if (event_notifier_init(&poll->stop_notifier, 0) < 0) {
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fprintf(stderr, "failed to init stop notifier\n");
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exit(1);
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}
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event_poll_add(poll, &poll->stop_handler,
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&poll->stop_notifier, handle_stop);
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}
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void event_poll_cleanup(EventPoll *poll)
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{
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event_notifier_cleanup(&poll->stop_notifier);
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close(poll->epoll_fd);
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poll->epoll_fd = -1;
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}
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/* Block until the next event and invoke its callback */
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void event_poll(EventPoll *poll)
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{
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EventHandler *handler;
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struct epoll_event event;
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int nevents;
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/* Wait for the next event. Only do one event per call to keep the
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* function simple, this could be changed later. */
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do {
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nevents = epoll_wait(poll->epoll_fd, &event, 1, -1);
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} while (nevents < 0 && errno == EINTR);
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if (unlikely(nevents != 1)) {
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fprintf(stderr, "epoll_wait failed: %m\n");
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exit(1); /* should never happen */
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}
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/* Find out which event handler has become active */
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handler = event.data.ptr;
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/* Clear the eventfd */
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event_notifier_test_and_clear(handler->notifier);
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/* Handle the event */
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handler->callback(handler);
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}
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/* Stop event_poll()
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*
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* This function can be used from another thread.
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*/
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void event_poll_notify(EventPoll *poll)
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{
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event_notifier_set(&poll->stop_notifier);
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}
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