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. Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1869952 Fixes: 1f050a4690f62a1e7dabc4f44141e9f762c3769f ("aio-posix: extract ppoll(2) and epoll(7) fd monitoring") Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com> Signed-off-by: Stefan Hajnoczi <stefa...@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); } -- 2.26.2
