From 5cd9c382b7ed3592c83b5b396db1a1298e323de0 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 15 Sep 2020 13:03:38 +0100 Subject: [PATCH] fdmon-poll: reset npfd when upgrading to fdmon-epoll MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit npfd keeps track of how many pollfds are currently being monitored. It must be reset to 0 when fdmon_poll_wait() returns. When npfd reaches a treshold we switch to fdmon-epoll because it scales better. This patch resets npfd in the case where we switch to fdmon-epoll. Forgetting to do so results in the following assertion failure: util/fdmon-poll.c:65: fdmon_poll_wait: Assertion `npfd == 0' failed. Fixes: 1f050a4690f62a1e7dabc4f44141e9f762c3769f ("aio-posix: extract ppoll(2) and epoll(7) fd monitoring") Signed-off-by: Stefan Hajnoczi Reviewed-by: Philippe Mathieu-Daudé Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1869952 Message-Id: <20200915120339.702938-2-stefanha@redhat.com> --- util/fdmon-poll.c | 1 + 1 file changed, 1 insertion(+) diff --git a/util/fdmon-poll.c b/util/fdmon-poll.c index 488067b679..5fe3b47865 100644 --- a/util/fdmon-poll.c +++ b/util/fdmon-poll.c @@ -73,6 +73,7 @@ static int fdmon_poll_wait(AioContext *ctx, AioHandlerList *ready_list, /* epoll(7) is faster above a certain number of fds */ if (fdmon_epoll_try_upgrade(ctx, npfd)) { + npfd = 0; /* we won't need pollfds[], reset npfd */ return ctx->fdmon_ops->wait(ctx, ready_list, timeout); }