From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752830AbeEUO7S (ORCPT ); Mon, 21 May 2018 10:59:18 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:37672 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752569AbeEUO7P (ORCPT ); Mon, 21 May 2018 10:59:15 -0400 Date: Mon, 21 May 2018 17:59:14 +0300 From: "Michael S. Tsirkin" To: Jason Wang Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net 3/4] virtio-net: reset num_buf to 1 after linearizing packet Message-ID: <20180521174725-mutt-send-email-mst@kernel.org> References: <1526891706-18516-1-git-send-email-jasowang@redhat.com> <1526891706-18516-4-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1526891706-18516-4-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > offset = VIRTIO_XDP_HEADROOM; > } else { > xdp_page = page; > -- > 2.7.4