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Sergio Lopez authoredevent_notifier_get_fd(const EventNotifier *e) always returns EventNotifier's read file descriptor (rfd). This is not a problem when the EventNotifier is backed by a an eventfd, as a single file descriptor is used both for reading and triggering events (rfd == wfd). But, when EventNotifier is backed by a pipe pair, we have two file descriptors, one that can only be used for reads (rfd), and the other only for writes (wfd). There's, at least, one known situation in which we need to obtain wfd instead of rfd, which is when setting up the file that's going to be sent to the peer in vhost's SET_VRING_CALL. Add a new event_notifier_get_wfd(const EventNotifier *e) that can be used to obtain wfd where needed. Signed-off-by:
Sergio Lopez <slp@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220304100854.14829-2-slp@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>Sergio Lopez authoredevent_notifier_get_fd(const EventNotifier *e) always returns EventNotifier's read file descriptor (rfd). This is not a problem when the EventNotifier is backed by a an eventfd, as a single file descriptor is used both for reading and triggering events (rfd == wfd). But, when EventNotifier is backed by a pipe pair, we have two file descriptors, one that can only be used for reads (rfd), and the other only for writes (wfd). There's, at least, one known situation in which we need to obtain wfd instead of rfd, which is when setting up the file that's going to be sent to the peer in vhost's SET_VRING_CALL. Add a new event_notifier_get_wfd(const EventNotifier *e) that can be used to obtain wfd where needed. Signed-off-by:
Sergio Lopez <slp@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220304100854.14829-2-slp@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
event_notifier.h 975 B
/*
* event notifier support
*
* Copyright Red Hat, Inc. 2010
*
* Authors:
* Michael S. Tsirkin <mst@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef QEMU_EVENT_NOTIFIER_H
#define QEMU_EVENT_NOTIFIER_H
#ifdef _WIN32
#include <windows.h>
#endif
struct EventNotifier {
#ifdef _WIN32
HANDLE event;
#else
int rfd;
int wfd;
bool initialized;
#endif
};
typedef void EventNotifierHandler(EventNotifier *);
int event_notifier_init(EventNotifier *, int active);
void event_notifier_cleanup(EventNotifier *);
int event_notifier_set(EventNotifier *);
int event_notifier_test_and_clear(EventNotifier *);
#ifdef CONFIG_POSIX
void event_notifier_init_fd(EventNotifier *, int fd);
int event_notifier_get_fd(const EventNotifier *);
int event_notifier_get_wfd(const EventNotifier *);
#else
HANDLE event_notifier_get_handle(EventNotifier *);
#endif
#endif