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Commit 68c33163 authored by Pravin B Shelar's avatar Pravin B Shelar Committed by David S. Miller
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v4 GRE: Add TCP segmentation offload for GRE 



Following patch adds GRE protocol offload handler so that
skb_gso_segment() can segment GRE packets.
SKB GSO CB is added to keep track of total header length so that
skb_segment can push entire header. e.g. in case of GRE, skb_segment
need to push inner and outer headers to every segment.
New NETIF_F_GRE_GSO feature is added for devices which support HW
GRE TSO offload. Currently none of devices support it therefore GRE GSO
always fall backs to software GSO.

[ Compute pkt_len before ip_local_out() invocation. -DaveM ]

Signed-off-by: default avatarPravin B Shelar <pshelar@nicira.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 05e8ef4a

include/linux/netdev_features.h

+2 −1
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ enum { 
	NETIF_F_TSO_ECN_BIT,		/* ... TCP ECN support */

	NETIF_F_TSO6_BIT,		/* ... TCPv6 segmentation */

	NETIF_F_FSO_BIT,		/* ... FCoE segmentation */

	NETIF_F_GSO_RESERVED1,		/* ... free (fill GSO_MASK to 8 bits) */

	NETIF_F_GSO_GRE_BIT,		/* ... GRE with TSO */

	/**/NETIF_F_GSO_LAST,		/* [can't be last bit, see GSO_MASK] */

	NETIF_F_GSO_RESERVED2		/* ... free (fill GSO_MASK to 8 bits) */

		= NETIF_F_GSO_LAST,
@@ -102,6 +102,7 @@ enum { 
#define NETIF_F_VLAN_CHALLENGED	__NETIF_F(VLAN_CHALLENGED)

#define NETIF_F_RXFCS		__NETIF_F(RXFCS)

#define NETIF_F_RXALL		__NETIF_F(RXALL)

#define NETIF_F_GRE_GSO		__NETIF_F(GSO_GRE)



/* Features valid for ethtool to change */

/* = all defined minus driver/device-class-related */

include/linux/skbuff.h

+17 −0
Original line number Diff line number Diff line
@@ -314,6 +314,8 @@ enum { 
	SKB_GSO_TCPV6 = 1 << 4,



	SKB_GSO_FCOE = 1 << 5,



	SKB_GSO_GRE = 1 << 6,

};



#if BITS_PER_LONG > 32
@@ -2732,6 +2734,21 @@ static inline struct sec_path *skb_sec_path(struct sk_buff *skb) 
}

#endif



/* Keeps track of mac header offset relative to skb->head.

 * It is useful for TSO of Tunneling protocol. e.g. GRE.

 * For non-tunnel skb it points to skb_mac_header() and for

 * tunnel skb it points to outer mac header. */

struct skb_gso_cb {

	int mac_offset;

};

#define SKB_GSO_CB(skb) ((struct skb_gso_cb *)(skb)->cb)



static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)

{

	return (skb_mac_header(inner_skb) - inner_skb->head) -

		SKB_GSO_CB(inner_skb)->mac_offset;

}



static inline bool skb_is_gso(const struct sk_buff *skb)

{

	return skb_shinfo(skb)->gso_size;

net/core/dev.c

+1 −0
Original line number Diff line number Diff line
@@ -2413,6 +2413,7 @@ struct sk_buff *__skb_gso_segment(struct sk_buff *skb, 
			return ERR_PTR(err);

	}



	SKB_GSO_CB(skb)->mac_offset = skb_headroom(skb);

	skb_reset_mac_header(skb);

	skb_reset_mac_len(skb);

net/core/ethtool.c

+1 −0
Original line number Diff line number Diff line
@@ -77,6 +77,7 @@ static const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN] 
	[NETIF_F_TSO_ECN_BIT] =          "tx-tcp-ecn-segmentation",

	[NETIF_F_TSO6_BIT] =             "tx-tcp6-segmentation",

	[NETIF_F_FSO_BIT] =              "tx-fcoe-segmentation",

	[NETIF_F_GSO_GRE_BIT] =		 "tx-gre-segmentation",



	[NETIF_F_FCOE_CRC_BIT] =         "tx-checksum-fcoe-crc",

	[NETIF_F_SCTP_CSUM_BIT] =        "tx-checksum-sctp",

net/core/skbuff.c

+5 −1
Original line number Diff line number Diff line
@@ -2738,6 +2738,7 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) 
	unsigned int mss = skb_shinfo(skb)->gso_size;

	unsigned int doffset = skb->data - skb_mac_header(skb);

	unsigned int offset = doffset;

	unsigned int tnl_hlen = skb_tnl_header_len(skb);

	unsigned int headroom;

	unsigned int len;

	int sg = !!(features & NETIF_F_SG);
@@ -2814,7 +2815,10 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) 
		skb_set_network_header(nskb, skb->mac_len);

		nskb->transport_header = (nskb->network_header +

					  skb_network_header_len(skb));

		skb_copy_from_linear_data(skb, nskb->data, doffset);



		skb_copy_from_linear_data_offset(skb, -tnl_hlen,

						 nskb->data - tnl_hlen,

						 doffset + tnl_hlen);



		if (fskb != skb_shinfo(skb)->frag_list)

			continue;