From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754252Ab3L0DTX (ORCPT ); Thu, 26 Dec 2013 22:19:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37035 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754125Ab3L0DTU (ORCPT ); Thu, 26 Dec 2013 22:19:20 -0500 Message-ID: <52BCF1A5.1080300@redhat.com> Date: Fri, 27 Dec 2013 11:19:01 +0800 From: Jason Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: "Michael S. Tsirkin" , netdev@vger.kernel.org CC: David Miller , Rusty Russell , Michael Dalton , Eric Dumazet , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH stable v2 1/3] virtio_net: fix error handling for mergeable buffers References: <1388064752-15734-1-git-send-email-mst@redhat.com> <1388064752-15734-2-git-send-email-mst@redhat.com> In-Reply-To: <1388064752-15734-2-git-send-email-mst@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/26/2013 09:32 PM, Michael S. Tsirkin wrote: > Eric Dumazet noticed that if we encounter an error > when processing a mergeable buffer, we don't > dequeue all of the buffers from this packet, > the result is almost sure to be loss of networking. > > Fix this issue. > > Cc: Rusty Russell > Cc: Michael Dalton > Acked-by: Michael Dalton > Cc: Eric Dumazet > Cc: Jason Wang > Cc: David S. Miller > > Signed-off-by: Michael S. Tsirkin > > (cherry picked from commit 8fc3b9e9a229778e5af3aa453c44f1a3857ba769) > --- > drivers/net/virtio_net.c | 66 +++++++++++++++++++++++++++++++++--------------- > 1 file changed, 46 insertions(+), 20 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 9fbdfcd..435076f 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -297,26 +297,33 @@ static struct sk_buff *page_to_skb(struct receive_queue *rq, > return skb; > } > > -static int receive_mergeable(struct receive_queue *rq, struct sk_buff *skb) > +static struct sk_buff *receive_mergeable(struct net_device *dev, > + struct receive_queue *rq, > + void *buf, > + unsigned int len) > { > - struct skb_vnet_hdr *hdr = skb_vnet_hdr(skb); > - struct page *page; > - int num_buf, i, len; > + struct skb_vnet_hdr *hdr = page_address(buf); > + int num_buf = hdr->mhdr.num_buffers; > + struct page *page = buf; > + struct sk_buff *skb = page_to_skb(rq, page, len); > + int i; > + > + if (unlikely(!skb)) > + goto err_skb; > > - num_buf = hdr->mhdr.num_buffers; > while (--num_buf) { > i = skb_shinfo(skb)->nr_frags; > if (i >= MAX_SKB_FRAGS) { > pr_debug("%s: packet too long\n", skb->dev->name); > skb->dev->stats.rx_length_errors++; > - return -EINVAL; > + return NULL; > } > page = virtqueue_get_buf(rq->vq, &len); > if (!page) { > - pr_debug("%s: rx error: %d buffers missing\n", > - skb->dev->name, hdr->mhdr.num_buffers); > - skb->dev->stats.rx_length_errors++; > - return -EINVAL; > + pr_debug("%s: rx error: %d buffers %d missing\n", > + dev->name, hdr->mhdr.num_buffers, num_buf); > + dev->stats.rx_length_errors++; > + goto err_buf; > } > > if (len > PAGE_SIZE) > @@ -326,7 +333,25 @@ static int receive_mergeable(struct receive_queue *rq, struct sk_buff *skb) > > --rq->num; > } > - return 0; > + return skb; > +err_skb: > + give_pages(rq, page); > + while (--num_buf) { > + buf = virtqueue_get_buf(rq->vq, &len); > + if (unlikely(!buf)) { > + pr_debug("%s: rx error: %d buffers missing\n", > + dev->name, num_buf); > + dev->stats.rx_length_errors++; > + break; > + } > + page = buf; > + give_pages(rq, page); > + --rq->num; > + } > +err_buf: > + dev->stats.rx_dropped++; > + dev_kfree_skb(skb); > + return NULL; > } > > static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len) > @@ -354,17 +379,18 @@ static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len) > skb_trim(skb, len); > } else { > page = buf; > - skb = page_to_skb(rq, page, len); > - if (unlikely(!skb)) { > - dev->stats.rx_dropped++; > - give_pages(rq, page); > - return; > - } > - if (vi->mergeable_rx_bufs) > - if (receive_mergeable(rq, skb)) { > - dev_kfree_skb(skb); > + if (vi->mergeable_rx_bufs) { > + skb = receive_mergeable(dev, rq, page, len); > + if (unlikely(!skb)) > + return; > + } else { > + skb = page_to_skb(rq, page, len); > + if (unlikely(!skb)) { > + dev->stats.rx_dropped++; > + give_pages(rq, page); > return; > } > + } > } > > hdr = skb_vnet_hdr(skb); Acked-by: Jason Wang