similar to: [PATCH net-next V3 1/2] net: introduce skb_coalesce_rx_frag()

Sometimes we need to coalesce the rx frags to avoid frag list. One example is virtio-net driver which tries to use small frags for both MTU sized packet and GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet

Sometimes we need to coalesce the rx frags to avoid frag list. One example is virtio-net driver which tries to use small frags for both MTU sized packet and GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet

Sometimes we need to coalesce the rx frags to avoid frag list. One example is virtio-net driver which tries to use small frags for both MTU sized packet and GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet

Sometimes we need to coalesce the rx frags to avoid frag list. One example is virtio-net driver which tries to use small frags for both MTU sized packet and GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet

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 <rusty at

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 <rusty at

On Thu, Oct 31, 2013 at 6:28 PM, Jason Wang <jasowang at redhat.com> wrote: > Sometimes we need to coalesce the rx frags to avoid frag list. One example is > virtio-net driver which tries to use small frags for both MTU sized packet and > GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. > > Cc: Rusty Russell <rusty at rustcorp.com.au> > Cc:

On Thu, Oct 31, 2013 at 6:28 PM, Jason Wang <jasowang at redhat.com> wrote: > Sometimes we need to coalesce the rx frags to avoid frag list. One example is > virtio-net driver which tries to use small frags for both MTU sized packet and > GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. > > Cc: Rusty Russell <rusty at rustcorp.com.au> > Cc:

On Thu, 2013-10-31 at 19:47 +0800, Jason Wang wrote: > Sometimes we need to coalesce the rx frags to avoid frag list. One example is > virtio-net driver which tries to use small frags for both MTU sized packet and > GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. > > Cc: Rusty Russell <rusty at rustcorp.com.au> > Cc: Michael S. Tsirkin <mst at

On 10/31/2013 07:05 PM, Kmindg G wrote: > On Thu, Oct 31, 2013 at 6:28 PM, Jason Wang <jasowang at redhat.com> wrote: >> > Sometimes we need to coalesce the rx frags to avoid frag list. One example is >> > virtio-net driver which tries to use small frags for both MTU sized packet and >> > GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this.

Commit 2613af0ed18a ("virtio_net: migrate mergeable rx buffers to page frag allocators") changed the mergeable receive buffer size from PAGE_SIZE to MTU-size. However, the merge buffer size does not take into account the size of the virtio-net header. Consequently, packets that are MTU-size will take two buffers intead of one (to store the virtio-net header), substantially decreasing the

Commit 2613af0ed18a ("virtio_net: migrate mergeable rx buffers to page frag allocators") changed the mergeable receive buffer size from PAGE_SIZE to MTU-size. However, the merge buffer size does not take into account the size of the virtio-net header. Consequently, packets that are MTU-size will take two buffers intead of one (to store the virtio-net header), substantially decreasing the

We need to drop the refcnt of page when we fail to allocate an skb for frag list, otherwise it will be leaked. The bug was introduced by commit 2613af0ed18a11d5c566a81f9a6510b73180660a ("virtio_net: migrate mergeable rx buffers to page frag allocators"). Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet <edumazet at google.com> Cc: Rusty Russell <rusty at

We need to drop the refcnt of page when we fail to allocate an skb for frag list, otherwise it will be leaked. The bug was introduced by commit 2613af0ed18a11d5c566a81f9a6510b73180660a ("virtio_net: migrate mergeable rx buffers to page frag allocators"). Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet <edumazet at google.com> Cc: Rusty Russell <rusty at

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

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

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 <rusty at

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 <rusty at

On 12/17/2013 08:16 AM, Michael Dalton wrote: > The virtio-net driver currently uses netdev_alloc_frag() for GFP_ATOMIC > mergeable rx buffer allocations. This commit migrates virtio-net to use > per-receive queue page frags for GFP_ATOMIC allocation. This change unifies > mergeable rx buffer memory allocation, which now will use skb_refill_frag() > for both atomic and GFP-WAIT

On 12/17/2013 08:16 AM, Michael Dalton wrote: > The virtio-net driver currently uses netdev_alloc_frag() for GFP_ATOMIC > mergeable rx buffer allocations. This commit migrates virtio-net to use > per-receive queue page frags for GFP_ATOMIC allocation. This change unifies > mergeable rx buffer memory allocation, which now will use skb_refill_frag() > for both atomic and GFP-WAIT