From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752163AbeEVDgZ (ORCPT ); Mon, 21 May 2018 23:36:25 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:50308 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751719AbeEVDgY (ORCPT ); Mon, 21 May 2018 23:36:24 -0400 Subject: Re: [PATCH net 3/4] virtio-net: reset num_buf to 1 after linearizing packet To: "Michael S. Tsirkin" Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <1526891706-18516-1-git-send-email-jasowang@redhat.com> <1526891706-18516-4-git-send-email-jasowang@redhat.com> <20180521174725-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: Date: Tue, 22 May 2018 11:36:18 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180521174725-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018年05月21日 22:59, Michael S. Tsirkin wrote: > On Mon, May 21, 2018 at 04:35:05PM +0800, Jason Wang wrote: >> If we successfully linearize the packets, num_buf were set to zero >> which was wrong since we now have only 1 buffer to be used for e.g in >> the error path of receive_mergeable(). Zero num_buf will lead the code >> try to pop the buffers of next packet and drop it. Fixing this by set >> num_buf to 1 if we successfully linearize the packet. >> >> Fixes: 4941d472bf95 ("virtio-net: do not reset during XDP set") >> Signed-off-by: Jason Wang >> --- >> drivers/net/virtio_net.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >> index 6260d65..165a922 100644 >> --- a/drivers/net/virtio_net.c >> +++ b/drivers/net/virtio_net.c >> @@ -722,6 +722,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, >> &len); >> if (!xdp_page) >> goto err_xdp; >> + num_buf = 1; > So this is tweaked here for the benefit of err_skb below. > That's confusing and we won't remember to change it > if we change the error handling. > > How about fixing the error path? > > > - while (--num_buf) { > + while (num_buf-- > 1) { > > Seems more robust to me. Looks good, will do this in V2. Thanks > >> offset = VIRTIO_XDP_HEADROOM; >> } else { >> xdp_page = page; >> -- >> 2.7.4