On Wed, 2 Mar 2022 12:36:43 +0100 Sergio Lopez <slp@xxxxxxxxxx> wrote: > 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 pipefd, 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. > > Extend event_notifier_get_fd() to receive an argument which indicates > whether the caller wants to obtain rfd (false) or wfd (true). There are about 50 places where we add the false arg here and 1 where we use true. Seems it would save a lot of churn to hide this internally, event_notifier_get_fd() returns an rfd, a new event_notifier_get_wfd() returns the wfd. Thanks, Alex
