From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753352AbdLRGPY (ORCPT ); Mon, 18 Dec 2017 01:15:24 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41154 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750727AbdLRGPX (ORCPT ); Mon, 18 Dec 2017 01:15:23 -0500 Date: Mon, 18 Dec 2017 08:15:22 +0200 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Jason Wang , virtualization@lists.linux-foundation.org Subject: [PATCH v2] virtio/ringtest: fix up need_event math Message-ID: <1513577626-1220-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Mutt-Fcc: =sent X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Mon, 18 Dec 2017 06:15:23 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org last kicked event index must be updated unconditionally: even if we don't need to kick, we do not want to re-check the same entry for events. Signed-off-by: Michael S. Tsirkin --- Changes from v1: fix inverted logic in call_used tools/virtio/ringtest/ring.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/tools/virtio/ringtest/ring.c b/tools/virtio/ringtest/ring.c index 747c5dd..2b9859b 100644 --- a/tools/virtio/ringtest/ring.c +++ b/tools/virtio/ringtest/ring.c @@ -188,16 +188,18 @@ bool enable_call() void kick_available(void) { + bool need; + /* Flush in previous flags write */ /* Barrier C (for pairing) */ smp_mb(); - if (!need_event(event->kick_index, - guest.avail_idx, - guest.kicked_avail_idx)) - return; + need = need_event(event->kick_index, + guest.avail_idx, + guest.kicked_avail_idx); guest.kicked_avail_idx = guest.avail_idx; - kick(); + if (need) + kick(); } /* host side */ @@ -253,14 +255,18 @@ bool use_buf(unsigned *lenp, void **bufp) void call_used(void) { + bool need; + /* Flush in previous flags write */ /* Barrier D (for pairing) */ smp_mb(); - if (!need_event(event->call_index, + + need = need_event(event->call_index, host.used_idx, - host.called_used_idx)) - return; + host.called_used_idx); host.called_used_idx = host.used_idx; - call(); + + if (need) + call(); } -- MST