Re: [PATCH v2 1/2] virtio_net: fix error handling for mergeable buffers
From: "Michael S. Tsirkin" Date: Thu, 28 Nov 2013 13:30:55 +0200 > 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. > > Cc: Rusty Russell > Cc: Michael Dalton > Reported-by: Eric Dumazet > Reported-by: Jason Wang > Signed-off-by: Michael S. Tsirkin Applied. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 1/2] virtio_net: fix error handling for mergeable buffers
On 11/28/2013 07:30 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.
>
> 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.
>
> Cc: Rusty Russell
> Cc: Michael Dalton
> Reported-by: Eric Dumazet
> Reported-by: Jason Wang
> Signed-off-by: Michael S. Tsirkin
> ---
>
> Stable patch will be sent later.
>
> drivers/net/virtio_net.c | 82
> ++--
> 1 file changed, 51 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7bab4de..5408de6 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -299,35 +299,47 @@ 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
> @@ -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);
> + 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;
[PATCH v2 1/2] virtio_net: fix error handling for mergeable buffers
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.
Cc: Rusty Russell
Cc: Michael Dalton
Reported-by: Eric Dumazet
Reported-by: Jason Wang
Signed-off-by: Michael S. Tsirkin
---
Stable patch will be sent later.
drivers/net/virtio_net.c | 82 ++--
1 file changed, 51 insertions(+), 31 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7bab4de..5408de6 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -299,35 +299,47 @@ 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
@@ -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);
+ 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;
}
-
