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

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Date:   Fri, 22 Sep 2017 19:15:24 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Willem de Bruijn <willemb@...gle.com>,
        Network Development <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCH net] net: orphan frags on stand-alone ptype in dev_queue_xmit_nit

On Fri, Sep 22, 2017 at 7:04 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> 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 <willemb@...gle.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 ?

Oh, yes, of course! :/ Will fix right away.