From 3bcf0fb3f2b4ab4ceeab488af1a3f7f8b8d70ba4 Mon Sep 17 00:00:00 2001 From: Sergio Lopez Date: Fri, 4 Mar 2022 11:08:51 +0100 Subject: [PATCH] event_notifier: add event_notifier_get_wfd() event_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 Reviewed-by: Stefan Hajnoczi Message-Id: <20220304100854.14829-2-slp@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- include/qemu/event_notifier.h | 1 + util/event_notifier-posix.c | 5 +++++ 2 files changed, 6 insertions(+) diff --git a/include/qemu/event_notifier.h b/include/qemu/event_notifier.h index b79add035d..8a4ff308e1 100644 --- a/include/qemu/event_notifier.h +++ b/include/qemu/event_notifier.h @@ -38,6 +38,7 @@ 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 diff --git a/util/event_notifier-posix.c b/util/event_notifier-posix.c index 8307013c5d..16294e98d4 100644 --- a/util/event_notifier-posix.c +++ b/util/event_notifier-posix.c @@ -99,6 +99,11 @@ int event_notifier_get_fd(const EventNotifier *e) return e->rfd; } +int event_notifier_get_wfd(const EventNotifier *e) +{ + return e->wfd; +} + int event_notifier_set(EventNotifier *e) { static const uint64_t value = 1;