From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752603Ab3KTJIE (ORCPT ); Wed, 20 Nov 2013 04:08:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52763 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751308Ab3KTJH5 (ORCPT ); Wed, 20 Nov 2013 04:07:57 -0500 From: Jason Wang To: rusty@rustcorp.com.au, mst@redhat.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jason Wang , Michael Dalton , Eric Dumazet , Shirley Ma Subject: [PATCH net 1/3] virtio-net: drop the rest of buffers when we can't allocate skb Date: Wed, 20 Nov 2013 17:07:25 +0800 Message-Id: <1384938447-3775-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When mergeable buffer were used, we only put the first page buf leave the rest of buffers in the virt queue. This will cause the driver could not get the correct head buffer any more. Fix this by dropping the rest of buffers for this packet. The bug was introduced by commit 9ab86bbcf8be755256f0a5e994e0b38af6b4d399 (virtio_net: Defer skb allocation in receive path). Cc: Rusty Russell Cc: Michael S. Tsirkin Cc: Michael Dalton Cc: Eric Dumazet Cc: Shirley Ma Signed-off-by: Jason Wang --- This patch was needed for stable --- drivers/net/virtio_net.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 7bab4de..24fd502 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -222,6 +222,17 @@ static void skb_xmit_done(struct virtqueue *vq) netif_wake_subqueue(vi->dev, vq2txq(vq)); } +static void drop_mergeable_buffer(struct receive_queue *rq, int num_buf) +{ + char *buf; + int len; + + while (--num_buf && (buf = virtqueue_get_buf(rq->vq, &len)) != NULL) { + --rq->num; + put_page(virt_to_head_page(buf)); + } +} + /* Called from bottom half context */ static struct sk_buff *page_to_skb(struct receive_queue *rq, struct page *page, unsigned int offset, @@ -237,8 +248,13 @@ static struct sk_buff *page_to_skb(struct receive_queue *rq, /* copy small packet so we can reuse these pages for small data */ skb = netdev_alloc_skb_ip_align(vi->dev, GOOD_COPY_LEN); - if (unlikely(!skb)) + if (unlikely(!skb)) { + if (vi->mergeable_rx_bufs) { + hdr = (struct skb_vnet_hdr *)p; + drop_mergeable_buffer(rq, hdr->mhdr.num_buffers); + } return NULL; + } hdr = skb_vnet_hdr(skb); -- 1.8.3.2