From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 0C27258CB; Fri, 1 Sep 2017 08:26:51 +0200 (CEST) Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3DD64461D2; Fri, 1 Sep 2017 06:26:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 3DD64461D2 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=jfreimann@redhat.com Received: from localhost (dhcp-192-218.str.redhat.com [10.33.192.218]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 54D425C883; Fri, 1 Sep 2017 06:26:47 +0000 (UTC) Date: Fri, 1 Sep 2017 08:26:46 +0200 From: Jens Freimann To: Tiwei Bie Cc: dev@dpdk.org, yliu@fridaylinux.org, maxime.coquelin@redhat.com, stable@dpdk.org Message-ID: <20170901062646.iek4azi6nez7vyrr@dhcp-192-218.str.redhat.com> References: <20170829082601.30349-1-tiwei.bie@intel.com> <20170830091306.a5whdd7xrgb4jbtn@dhcp-192-218.str.redhat.com> <20170830102423.GA15019@debian-ZGViaWFuCg> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20170830102423.GA15019@debian-ZGViaWFuCg> User-Agent: NeoMutt/20170714 (1.8.3) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 01 Sep 2017 06:26:51 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH] net/virtio: fix an incorrect behavior of device stop/start X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 Sep 2017 06:26:52 -0000 On Wed, Aug 30, 2017 at 06:24:24PM +0800, Tiwei Bie wrote: >Hi Jens, > >On Wed, Aug 30, 2017 at 11:13:06AM +0200, Jens Freimann wrote: >> Hi Tiwei, >> >> On Tue, Aug 29, 2017 at 04:26:01PM +0800, Tiwei Bie wrote: >> > After starting a device, the driver shouldn't deliver the >> > packets that already existed in the device before it is >> > started to the applications. This patch fixes this issue >> > by flushing the Rx queues when starting the device. >> > >> > Fixes: a85786dc816f ("virtio: fix states handling during initialization") >> > Cc: stable@dpdk.org >> > >> > Signed-off-by: Tiwei Bie >> > --- >> > drivers/net/virtio/virtio_ethdev.c | 6 ++++++ >> > drivers/net/virtio/virtio_rxtx.c | 2 +- >> > drivers/net/virtio/virtqueue.c | 25 +++++++++++++++++++++++++ >> > drivers/net/virtio/virtqueue.h | 5 +++++ >> > 4 files changed, 37 insertions(+), 1 deletion(-) >> >> why don't we flush Tx queues as well? >> > >The elements in the used ring of Tx queues won't be delivered >to the applications. They don't contain any (packet) data, and >will just be recycled during Tx. So there is no need to flush >the Tx queues. ok, but it would hurt either because it's not performance relevant and we could be sure to always start with an empty queue. It can be done in a different patch though I guess. >> > >> > diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c >> > index e320811..6d60bc1 100644 >> > --- a/drivers/net/virtio/virtio_ethdev.c >> > +++ b/drivers/net/virtio/virtio_ethdev.c >> > @@ -1737,6 +1737,12 @@ virtio_dev_start(struct rte_eth_dev *dev) >> > } >> > } >> > >> > + /* Flush the packets in Rx queues. */ >> > + for (i = 0; i < dev->data->nb_rx_queues; i++) { >> > + rxvq = dev->data->rx_queues[i]; >> > + virtqueue_flush(rxvq->vq); >> > + } >> > + >> >> A little bit further down is a for loop going over rx queues calling >> notify. Could we flush directly before the notify and save the >> additional loop? >> > >I saw there is also another `for' loop to dump the Rx queues. >And I think it makes the code more readable to flush the Rx >queues in a separate `for' loop too. Besides, this function >isn't performance critical. So I didn't combine them into one >`for' loop. To me code is better readable when it is concise, so I'd still vote for combining the loops if its logically equivalent. On the other hand I think this should be fixed soon, so Reviewed-by: Jens Freimann regards, Jens