Re: [Xen-devel] [PATCH net-next v3 6/9] xen-netback: Handle guests with too many frags

[Eric Dumazet <eric.dumazet@xxxxxxxxx>]

On Wed, 2014-01-08 at 13:49 +0000, Zoltan Kiss wrote:
> On 08/01/14 02:12, Eric Dumazet wrote:
> > On Wed, 2014-01-08 at 00:10 +0000, Zoltan Kiss wrote:
> >
> >>
> >> +          if (skb_shinfo(skb)->frag_list) {
> >> +                  nskb = skb_shinfo(skb)->frag_list;
> >> +                  xenvif_fill_frags(vif, nskb, INVALID_PENDING_IDX);
> >> +                  skb->len += nskb->len;
> >> +                  skb->data_len += nskb->len;
> >> +                  skb->truesize += nskb->truesize;
> >> +                  skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
> >> +                  skb_shinfo(nskb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
> >> +                  vif->tx_zerocopy_sent += 2;
> >> +                  nskb = skb;
> >> +
> >> +                  skb = skb_copy_expand(skb,
> >> +                                  0,
> >> +                                  0,
> >> +                                  GFP_ATOMIC | __GFP_NOWARN);
> >
> > skb can be NULL here
> 
> Thanks, fixed that.

BTW, I am not sure why you copy the skb.

Is it to get rid of frag_list, and why ?






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