Re: [Xen-devel] [PATCH] xen-netfront: pull on receive skb may need to happen earlier

Jan Beulich
2013-07-09T06:52:31Z

>>> On 08.07.13 at 17:48, Wei Liu <wei.liu2@citrix.com> wrote:
> On Mon, Jul 08, 2013 at 03:20:26PM +0100, Jan Beulich wrote:
>> @@ -1014,7 +1025,7 @@ err:
>>
>> skb_shinfo(skb)->frags[0].page_offset = rx->offset;
>> skb_frag_size_set(&skb_shinfo(skb)->frags[0], rx->status);
>> - skb->data_len = rx->status;
>> + skb->len = skb->data_len = rx->status;
>
> This is not correct. You should not be needing this. Now you lose count
> of SKB head len. Try to go without the above line and see if it makes a
> difference?

I don't follow - at this point, there's 0 bytes of head (this only
changes with the first call to __pskb_pull_tail()). Hence ->len ==
->data_len seems correct to me (and afaict pulling would do the
wrong thing if I dropped that change).

Jan