Re: [PATCH net] net: orphan frags on stand-alone ptype in dev_queue_xmit_nit

[Eric Dumazet]

On Fri, 2017-09-22 at 18:51 -0400, Willem de Bruijn wrote:
> Zerocopy skbs frags are copied when the skb is looped to a local sock.
> Commit 1080e512d44d ("net: orphan frags on receive") introduced calls
> to skb_orphan_frags to deliver_skb and __netif_receive_skb.
> 
> With msg_zerocopy, these skbs can also exist in the tx path and thus
> loop from dev_queue_xmit_nit. This already calls deliver_skb in its
> loop. But it does not orphan before a separate pt_prev->func().
> 
> Add the missing skb_orphan_frags_rx.
> 
> Fixes: 1f8b977ab32d ("sock: enable MSG_ZEROCOPY")
> Signed-off-by: Willem de Bruijn <will...@google.com>
> ---
>  net/core/dev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 9a2254f9802f..3f5b26ff4f74 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -1948,7 +1948,7 @@ void dev_queue_xmit_nit(struct sk_buff *skb, struct 
> net_device *dev)
>               goto again;
>       }
>  out_unlock:
> -     if (pt_prev)
> +     if (pt_prev && !skb_orphan_frags_rx(skb2, GFP_ATOMIC))
>               pt_prev->func(skb2, skb->dev, pt_prev, skb->dev);

Don't you need to kfree_skb(skb2) in case of failure ?

>       rcu_read_unlock();
>  }