| Message ID | 1385569684-26595-1-git-send-email-mst@redhat.com |
|---|---|
| State | Awaiting Upstream, archived |
| Delegated to: | David Miller |
| Headers | show |
On 11/28/2013 12:31 AM, 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. > > 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 <rusty@rustcorp.com.au> > Cc: Michael Dalton <mwdalton@google.com> > Reported-by: Eric Dumazet <edumazet@google.com> > Reported-by: Jason Wang <jasowang@redhat.com> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > --- > > Note: this bugfix is needed on stable too, but backport > might not be trivial. > I'll send a backport for stable separately. That will be fine. > > 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; Not sure it's correct here. Since the we break immediately if buffer is missed in err_buf and rx_length_error will be miss counted. Maybe an ERR_PTR(-EINVAL) is better. > } > 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; This change seems unnecessary. Other looks good. > 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); -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Nov 28, 2013 at 11:14:45AM +0800, Jason Wang wrote: > On 11/28/2013 12:31 AM, 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. > > > > 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 <rusty@rustcorp.com.au> > > Cc: Michael Dalton <mwdalton@google.com> > > Reported-by: Eric Dumazet <edumazet@google.com> > > Reported-by: Jason Wang <jasowang@redhat.com> > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > --- > > > > Note: this bugfix is needed on stable too, but backport > > might not be trivial. > > I'll send a backport for stable separately. > > That will be fine. > > > > 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; > > Not sure it's correct here. Since the we break immediately if buffer is > missed in err_buf and rx_length_error will be miss counted. Note that this never happens: it's an internal device error, we are just trying to be defensive here. I would not worry about getting error counters right in this case. But I agree - since we know virtqueue_get_buf failed it's useless to try and get more. So let's move the loop before the err_buf label. > Maybe an ERR_PTR(-EINVAL) is better. This will just make callers worry about checking IS_ERR, and caller returns void so it has nothing to do with the return code anyway. > > } > > 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; > > This change seems unnecessary. Right, I'll drop it. > Other looks good. > > 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); -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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);
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 <rusty@rustcorp.com.au> Cc: Michael Dalton <mwdalton@google.com> Reported-by: Eric Dumazet <edumazet@google.com> Reported-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- 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(-)