Commit 3b392ddb authored Jun 04, 2014 by Simon Horman Committed by David S. Miller Jun 05, 2014

MPLS: Use mpls_features to activate software MPLS GSO segmentation



If an MPLS packet requires segmentation then use mpls_features
to determine if the software implementation should be used.

As no driver advertises MPLS GSO segmentation this will always be
the case.

I had not noticed that this was necessary before as software MPLS GSO
segmentation was already being used in my test environment. I believe that
the reason for that is the skbs in question always had fragments and the
driver I used does not advertise NETIF_F_FRAGLIST (which seems to be the
case for most drivers). Thus software segmentation was activated by
skb_gso_ok().

This introduces the overhead of an extra call to skb_network_protocol()
in the case where where CONFIG_NET_MPLS_GSO is set and
skb->ip_summed == CHECKSUM_NONE.

Thanks to Jesse Gross for prompting me to investigate this.

Signed-off-by: Simon Horman <horms@verge.net.au>
Acked-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent d68de60f

net/core/dev.c

+27 −1

Original line number	Diff line number	Diff line
		@@ -2513,13 +2513,39 @@ static int dev_gso_segment(struct sk_buff *skb, netdev_features_t features)
		return 0;
		}

		/* If MPLS offload request, verify we are testing hardware MPLS features
		* instead of standard features for the netdev.
		*/
		#ifdef CONFIG_NET_MPLS_GSO
		static netdev_features_t net_mpls_features(struct sk_buff *skb,
		netdev_features_t features,
		__be16 type)
		{
		if (type == htons(ETH_P_MPLS_UC) \|\| type == htons(ETH_P_MPLS_MC))
		features &= skb->dev->mpls_features;

		return features;
		}
		#else
		static netdev_features_t net_mpls_features(struct sk_buff *skb,
		netdev_features_t features,
		__be16 type)
		{
		return features;
		}
		#endif

		static netdev_features_t harmonize_features(struct sk_buff *skb,
		netdev_features_t features)
		{
		int tmp;
		__be16 type;

		type = skb_network_protocol(skb, &tmp);
		features = net_mpls_features(skb, features, type);

		if (skb->ip_summed != CHECKSUM_NONE &&
		!can_checksum_protocol(features, skb_network_protocol(skb, &tmp))) {
		!can_checksum_protocol(features, type)) {
		features &= ~NETIF_F_ALL_CSUM;
		} else if (illegal_highdma(skb->dev, skb)) {
		features &= ~NETIF_F_SG;