On 8/21/20 12:12 PM, Stefan Hajnoczi wrote: > 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") > 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); > } > >
Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>
