From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757158Ab3K0Q2M (ORCPT ); Wed, 27 Nov 2013 11:28:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44690 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752326Ab3K0Q2K (ORCPT ); Wed, 27 Nov 2013 11:28:10 -0500 Date: Wed, 27 Nov 2013 18:31:21 +0200 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Rusty Russell , Michael Dalton , Eric Dumazet , Jason Wang , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH 1/2] virtio_net: fix error handling for mergeable buffers Message-ID: <1385569684-26595-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Mutt-Fcc: =sent Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Jason Wang noticed that we also leak a page and that we don't decrement the rq buf count, so we won't repost buffers (a resource leak). Fix both issues, and also make the logic a bit more robust against device errors by not looping when e.g. because of a leak like the one we are fixing here the number of buffers is 0. Cc: Rusty Russell Cc: Michael Dalton Reported-by: Eric Dumazet Reported-by: Jason Wang Signed-off-by: Michael S. Tsirkin --- Note: this bugfix is needed on stable too, but backport might not be trivial. I'll send a backport for stable separately. drivers/net/virtio_net.c | 84 ++++++++++++++++++++++++++++++------------------ 1 file changed, 52 insertions(+), 32 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 7bab4de..0e6ea69 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -299,41 +299,53 @@ static struct sk_buff *page_to_skb(struct receive_queue *rq, return skb; } -static int receive_mergeable(struct receive_queue *rq, struct sk_buff *head_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(head_skb); + struct skb_vnet_hdr *hdr = buf; + int num_buf = hdr->mhdr.num_buffers; + struct page *page = virt_to_head_page(buf); + int offset = buf - page_address(page); + struct sk_buff *head_skb = page_to_skb(rq, page, offset, len, + MERGE_BUFFER_LEN); struct sk_buff *curr_skb = head_skb; - char *buf; - struct page *page; - int num_buf, len, offset; - num_buf = hdr->mhdr.num_buffers; + if (unlikely(!curr_skb)) + goto err_skb; + while (--num_buf) { - int num_skb_frags = skb_shinfo(curr_skb)->nr_frags; + int num_skb_frags; + buf = virtqueue_get_buf(rq->vq, &len); if (unlikely(!buf)) { - pr_debug("%s: rx error: %d buffers missing\n", - head_skb->dev->name, hdr->mhdr.num_buffers); - head_skb->dev->stats.rx_length_errors++; - return -EINVAL; + pr_debug("%s: rx error: %d buffers out of %d missing\n", + dev->name, num_buf, hdr->mhdr.num_buffers); + dev->stats.rx_length_errors++; + goto err_buf; } if (unlikely(len > MERGE_BUFFER_LEN)) { pr_debug("%s: rx error: merge buffer too long\n", - head_skb->dev->name); + dev->name); len = MERGE_BUFFER_LEN; } + + page = virt_to_head_page(buf); + --rq->num; + + num_skb_frags = skb_shinfo(curr_skb)->nr_frags; if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) { struct sk_buff *nskb = alloc_skb(0, GFP_ATOMIC); - if (unlikely(!nskb)) { - head_skb->dev->stats.rx_dropped++; - return -ENOMEM; - } + + if (unlikely(!nskb)) + goto err_skb; if (curr_skb == head_skb) skb_shinfo(curr_skb)->frag_list = nskb; else curr_skb->next = nskb; - curr_skb = nskb; head_skb->truesize += nskb->truesize; + curr_skb = nskb; num_skb_frags = 0; } if (curr_skb != head_skb) { @@ -341,8 +353,7 @@ static int receive_mergeable(struct receive_queue *rq, struct sk_buff *head_skb) head_skb->len += len; head_skb->truesize += MERGE_BUFFER_LEN; } - page = virt_to_head_page(buf); - offset = buf - (char *)page_address(page); + offset = buf - page_address(page); if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) { put_page(page); skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1, @@ -351,9 +362,28 @@ static int receive_mergeable(struct receive_queue *rq, struct sk_buff *head_skb) skb_add_rx_frag(curr_skb, num_skb_frags, page, offset, len, MERGE_BUFFER_LEN); } + } + + return head_skb; + +err_skb: + put_page(page); +err_buf: + dev->stats.rx_dropped++; + dev_kfree_skb(head_skb); + 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 = virt_to_head_page(buf); + put_page(page); --rq->num; } - return 0; + return NULL; } static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len) @@ -382,19 +412,9 @@ static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len) len -= sizeof(struct virtio_net_hdr); skb_trim(skb, len); } else if (vi->mergeable_rx_bufs) { - struct page *page = virt_to_head_page(buf); - skb = page_to_skb(rq, page, - (char *)buf - (char *)page_address(page), - len, MERGE_BUFFER_LEN); - if (unlikely(!skb)) { - dev->stats.rx_dropped++; - put_page(page); + skb = receive_mergeable(dev, rq, buf, len); + if (unlikely(!skb)) return; - } - if (receive_mergeable(rq, skb)) { - dev_kfree_skb(skb); - return; - } } else { page = buf; skb = page_to_skb(rq, page, 0, len, PAGE_SIZE); -- MST