On Mon, 22 Apr 2013, Simon Horman wrote:
> "net: Add support for hardware-offloaded encapsulation" introduced
> the encapsulation field of struct skb, which when set provides hints
> that GSO should handle an skb that encapsulates a packet.
>
> This patch adds an encapsulation_features field which provides
> a hint to dev dev_hard_start_xmit() that harware-offload encapsulation
> features should be used. Previously this hint was provided by the
> encapsulation field.
>
> The other uses of the encapsulation field are left unchanged.
>
> The two in-tree locations that set the encapsulation have been updated to
> also set encapsulation_field.
>
> The motivation for this is to provide support segmentation of GSO MPLS skbs.
> This may be necessary when a non-MPLS GSO skb is turned into an MPLS GSO
> skb by Open vSwtich and its MPLS push action.
>
> In this case it harware-offload encapsulation features should be used,
> actually to be more exact software segmentation should be selected, but
> other hints provided by the encapsulation field are not applicable.
>
> Cc: Joseph Gasparakis <joseph.gaspara...@intel.com>
> Cc: Peter P Waskiewicz Jr <peter.p.waskiewicz...@intel.com>
> Cc: Alexander Duyck <alexander.h.du...@intel.com>
> Signed-off-by: Simon Horman <ho...@verge.net.au>
> ---
> include/linux/skbuff.h | 9 ++++++++-
> net/core/dev.c | 2 +-
> net/core/skbuff.c | 1 +
> net/ipv4/gre.c | 1 +
> net/ipv4/ipip.c | 1 +
> 5 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 2e0ced1..d9ec1de 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -494,7 +494,14 @@ struct sk_buff {
> * headers if needed
> */
> __u8 encapsulation:1;
> - /* 7/9 bit hole (depending on ndisc_nodetype presence) */
> + /* Encapsulation protocol and NIC drivers should use
> + * this flag to indicate to each other if the skb contains
> + * encapsulated packet and GSO should use encapsulation features
> + * instead of standard features for the netdev. This is typically
> + * a subset of cases where skb->encapsulation is set.
> + */
> + __u8 encapsulation_features:1;
> + /* 6/8 bit hole (depending on ndisc_nodetype presence) */
> kmemcheck_bitfield_end(flags2);
>
> #ifdef CONFIG_NET_DMA
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 9e26b8d..53236c5 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2498,7 +2498,7 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct
> net_device *dev,
> * hardware encapsulation features instead of standard
> * features for the netdev
> */
> - if (skb->encapsulation)
> + if (skb->encapsulation_features)
> features &= dev->hw_enc_features;
>
> if (netif_needs_gso(skb, features)) {
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 898cf5c..f23d136 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -708,6 +708,7 @@ static void __copy_skb_header(struct sk_buff *new, const
> struct sk_buff *old)
> new->l4_rxhash = old->l4_rxhash;
> new->no_fcs = old->no_fcs;
> new->encapsulation = old->encapsulation;
> + new->encapsulation_features = old->encapsulation_features;
> #ifdef CONFIG_XFRM
> new->sp = secpath_get(old->sp);
> #endif
> diff --git a/net/ipv4/gre.c b/net/ipv4/gre.c
> index 0ae998b..8420f29 100644
> --- a/net/ipv4/gre.c
> +++ b/net/ipv4/gre.c
> @@ -157,6 +157,7 @@ static struct sk_buff *gre_gso_segment(struct sk_buff
> *skb,
> }
>
> skb->encapsulation = 0;
> + skb->encapsulation_features = 0;
>
> if (unlikely(!pskb_may_pull(skb, ghl)))
> goto out;
> diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
> index 77bfcce..a6db3c0 100644
> --- a/net/ipv4/ipip.c
> +++ b/net/ipv4/ipip.c
> @@ -220,6 +220,7 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb,
> struct net_device *dev)
> if (likely(!skb->encapsulation)) {
> skb_reset_inner_headers(skb);
> skb->encapsulation = 1;
> + skb->encapsulation_features = 1;
> }
>
> ip_tunnel_xmit(skb, dev, tiph);
>
Any particular reason to introduce skb->encapsulation_features instead of
using the existing skb->encapsulation? Also I don't see it used in your
second patch either.
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