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Date: Tue, 11 Nov 2014 05:06:21 -0800
From: Eric Dumazet <eric.dumazet@...il.com>
To: Jiri Pirko <jiri@...nulli.us>
Cc: netdev@...r.kernel.org, davem@...emloft.net, jhs@...atatu.com,
pshelar@...ira.com, therbert@...gle.com, edumazet@...gle.com,
willemb@...gle.com, dborkman@...hat.com, mst@...hat.com,
fw@...len.de, Paul.Durrant@...rix.com, tgraf@...g.ch
Subject: Re: [patch net-next 1/2] net: move vlan pop/push functions into
common code
On Tue, 2014-11-11 at 11:13 +0100, Jiri Pirko wrote:
> So it can be used from out of openvswitch code.
> Did couple of cosmetic changes on the way, namely variable naming and
> adding support for 8021AD proto.
>
> Signed-off-by: Jiri Pirko <jiri@...nulli.us>
> ---
> include/linux/skbuff.h | 2 ++
> net/core/skbuff.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++
> net/openvswitch/actions.c | 76 ++---------------------------------------
> 3 files changed, 90 insertions(+), 74 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 103fbe8..3b0445c 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2673,6 +2673,8 @@ void skb_scrub_packet(struct sk_buff *skb, bool xnet);
> unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
> struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
> struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
> +int skb_vlan_pop(struct sk_buff *skb);
> +int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
>
> struct skb_checksum_ops {
> __wsum (*update)(const void *mem, int len, __wsum wsum);
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 7001896..75e53d4 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -4151,6 +4151,92 @@ err_free:
> }
> EXPORT_SYMBOL(skb_vlan_untag);
>
> +/* remove VLAN header from packet and update csum accordingly. */
> +static int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
> +{
> + struct vlan_hdr *vhdr;
> + int err;
> +
> + if (!pskb_may_pull(skb, VLAN_ETH_HLEN))
> + return -ENOMEM;
> +
> + if (!skb_cloned(skb) || skb_clone_writable(skb, VLAN_ETH_HLEN))
> + return 0;
> +
> + err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
> + if (unlikely(err))
> + return err;
All this should be a function of its own (OVS calls this
make_writable()).
Its too bad netfilter has a different skb_make_writable()
> +
> + if (skb->ip_summed == CHECKSUM_COMPLETE)
> + skb->csum = csum_sub(skb->csum, csum_partial(skb->data
> + + (2 * ETH_ALEN), VLAN_HLEN, 0));
This looks like skb_postpull_rcsum()
BTW, calling csum_partial() for 4 bytes is quite expensive.
--
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