From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752238AbdJ0NLQ (ORCPT ); Fri, 27 Oct 2017 09:11:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53600 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751908AbdJ0NLP (ORCPT ); Fri, 27 Oct 2017 09:11:15 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 96AED6A7DF Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=mst@redhat.com Date: Fri, 27 Oct 2017 16:11:13 +0300 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Jason Wang , virtualization@lists.linux-foundation.org Subject: [PATCH] virtio/ringtest: virtio_ring: fix up need_event math Message-ID: <1509109839-553-1-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 [10.5.110.27]); Fri, 27 Oct 2017 13:11:15 +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. Reported-by: Cornelia Huck Signed-off-by: Michael S. Tsirkin --- tools/virtio/ringtest/virtio_ring_0_9.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/tools/virtio/ringtest/virtio_ring_0_9.c b/tools/virtio/ringtest/virtio_ring_0_9.c index bbc3043..5fd3fbc 100644 --- a/tools/virtio/ringtest/virtio_ring_0_9.c +++ b/tools/virtio/ringtest/virtio_ring_0_9.c @@ -225,16 +225,18 @@ bool enable_call() void kick_available(void) { + bool need; + /* Flush in previous flags write */ /* Barrier C (for pairing) */ smp_mb(); - if (!vring_need_event(vring_avail_event(&ring), - guest.avail_idx, - guest.kicked_avail_idx)) - return; + need = vring_need_event(vring_avail_event(&ring), + guest.avail_idx, + guest.kicked_avail_idx); guest.kicked_avail_idx = guest.avail_idx; - kick(); + if (need) + kick(); } /* host side */ @@ -316,14 +318,16 @@ 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 (!vring_need_event(vring_used_event(&ring), - host.used_idx, - host.called_used_idx)) - return; + need = vring_need_event(vring_used_event(&ring), + host.used_idx, + host.called_used_idx); host.called_used_idx = host.used_idx; - call(); + if (need) + call(); } -- MST