[ovs-dev] [PATCH net-next 1/2] net: Export skb_zerocopy() to zerocopy from one skb to another
Thomas Graf
tgraf at suug.ch
Fri May 24 16:01:06 UTC 2013
On 05/24/13 at 08:31am, Eric Dumazet wrote:
> Hmm. Big warning here : In the nfnetlink case, we specifically made sure
> that this path was taken only if skb->head_frag was set (all incoming
> packets have this property, but not outgoing ones yet)
>
> This should be documented if we move it to net/core/skbuff.c, or we
> should add a BUG_ON()
Good point.
I guess we could ensure in skb_zerocopy() that if !head_frag then we
enforce hlen = max(hlen, skb_headlen(skb)) to always fall back to
skb_copy_bits() for !head_frag.
> I see your openvswitch code seems OK.
>
> Maybe also put in net/core/skbuff.c the code dealing with this stuff ?
>
> + if (!skb->head_frag ||
> + skb_headlen(skb) < L1_CACHE_BYTES ||
> + skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS)
> + hlen = skb_headlen(skb);
> +
> + if (skb_has_frag_list(skb))
> + hlen = skb->len;
I'll put this into skb_zerocopy_hdrlen()
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