From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: [PATCH] virtio/ringtest: virtio_ring: fix up need_event math Date: Fri, 27 Oct 2017 16:11:13 +0300 Message-ID: <1509109839-553-1-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: linux-kernel@vger.kernel.org Cc: virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.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