Re: [PATCH net 1/3] virtio-net: drop the rest of buffers when we can't allocate skb
On Wed, Nov 20, 2013 at 05:07:25PM +0800, Jason Wang wrote: 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 ru...@rustcorp.com.au Cc: Michael S. Tsirkin m...@redhat.com Cc: Michael Dalton mwdal...@google.com Cc: Eric Dumazet eduma...@google.com Cc: Shirley Ma x...@us.ibm.com Signed-off-by: Jason Wang jasow...@redhat.com --- 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)); + } +} + This is the same code we have in receive_mergeable anyway. So let's reuse that. /* 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 ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH net 1/3] virtio-net: drop the rest of buffers when we can't allocate skb
- 原始邮件 - On Wed, Nov 20, 2013 at 05:07:25PM +0800, Jason Wang wrote: 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 ru...@rustcorp.com.au Cc: Michael S. Tsirkin m...@redhat.com Cc: Michael Dalton mwdal...@google.com Cc: Eric Dumazet eduma...@google.com Cc: Shirley Ma x...@us.ibm.com Signed-off-by: Jason Wang jasow...@redhat.com --- 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)); + } +} + This is the same code we have in receive_mergeable anyway. So let's reuse that. receive_mergeable() was called after page_to_skb() was called and there's lots of conditions check there. I'm not sure how could we reuse them. /* 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 -- 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/ ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH net 1/3] virtio-net: drop the rest of buffers when we can't allocate skb
On Wed, Nov 20, 2013 at 07:08:02AM -0500, Jason Wang wrote: - 原始邮件 - On Wed, Nov 20, 2013 at 05:07:25PM +0800, Jason Wang wrote: 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 ru...@rustcorp.com.au Cc: Michael S. Tsirkin m...@redhat.com Cc: Michael Dalton mwdal...@google.com Cc: Eric Dumazet eduma...@google.com Cc: Shirley Ma x...@us.ibm.com Signed-off-by: Jason Wang jasow...@redhat.com --- 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)); + } +} + This is the same code we have in receive_mergeable anyway. So let's reuse that. receive_mergeable() was called after page_to_skb() was called and there's lots of conditions check there. I'm not sure how could we reuse them. I posted a patch showing how :) /* 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 -- 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/ ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization