GSO: Add GSO type for fixed IPv4 ID

This patch adds support for TSO using IPv4 headers with a fixed IP ID
field.  This is meant to allow us to do a lossless GRO in the case of TCP
flows that use a fixed IP ID such as those that convert IPv6 header to IPv4
headers.

In addition I am adding a feature that for now I am referring to TSO with
IP ID mangling.  Basically when this flag is enabled the device has the
option to either output the flow with incrementing IP IDs or with a fixed
IP ID regardless of what the original IP ID ordering was.  This is useful
in cases where the DF bit is set and we do not care if the original IP ID
value is maintained.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 15 insertions, 9 deletions

diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
index a734bf4..7cf272a 100644
--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -39,6 +39,7 @@ enum {
 	NETIF_F_UFO_BIT,		/* ... UDPv4 fragmentation */
 	NETIF_F_GSO_ROBUST_BIT,		/* ... ->SKB_GSO_DODGY */
 	NETIF_F_TSO_ECN_BIT,		/* ... TCP ECN support */
+	NETIF_F_TSO_MANGLEID_BIT,	/* ... IPV4 ID mangling allowed */
 	NETIF_F_TSO6_BIT,		/* ... TCPv6 segmentation */
 	NETIF_F_FSO_BIT,		/* ... FCoE segmentation */
 	NETIF_F_GSO_GRE_BIT,		/* ... GRE with TSO */
@@ -120,6 +121,7 @@ enum {
 #define NETIF_F_GSO_SIT		__NETIF_F(GSO_SIT)
 #define NETIF_F_GSO_UDP_TUNNEL	__NETIF_F(GSO_UDP_TUNNEL)
 #define NETIF_F_GSO_UDP_TUNNEL_CSUM __NETIF_F(GSO_UDP_TUNNEL_CSUM)
+#define NETIF_F_TSO_MANGLEID	__NETIF_F(TSO_MANGLEID)
 #define NETIF_F_GSO_TUNNEL_REMCSUM __NETIF_F(GSO_TUNNEL_REMCSUM)
 #define NETIF_F_HW_VLAN_STAG_FILTER __NETIF_F(HW_VLAN_STAG_FILTER)
 #define NETIF_F_HW_VLAN_STAG_RX	__NETIF_F(HW_VLAN_STAG_RX)
@@ -147,6 +149,7 @@ enum {
 
 /* List of features with software fallbacks. */
 #define NETIF_F_GSO_SOFTWARE	(NETIF_F_TSO | NETIF_F_TSO_ECN | \
+				 NETIF_F_TSO_MANGLEID | \
 				 NETIF_F_TSO6 | NETIF_F_UFO)
 
 /* List of IP checksum features. Note that NETIF_F_ HW_CSUM should not be
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 9884fe9..8e372d0 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3992,6 +3992,7 @@ static inline bool net_gso_ok(netdev_features_t features, int gso_type)
 	BUILD_BUG_ON(SKB_GSO_UDP     != (NETIF_F_UFO >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_DODGY   != (NETIF_F_GSO_ROBUST >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_TCP_ECN != (NETIF_F_TSO_ECN >> NETIF_F_GSO_SHIFT));
+	BUILD_BUG_ON(SKB_GSO_TCP_FIXEDID != (NETIF_F_TSO_MANGLEID >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_TCPV6   != (NETIF_F_TSO6 >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_FCOE    != (NETIF_F_FSO >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_GRE     != (NETIF_F_GSO_GRE >> NETIF_F_GSO_SHIFT));
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 0073812..5fba166 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -465,23 +465,25 @@ enum {
 	/* This indicates the tcp segment has CWR set. */
 	SKB_GSO_TCP_ECN = 1 << 3,
 
-	SKB_GSO_TCPV6 = 1 << 4,
+	SKB_GSO_TCP_FIXEDID = 1 << 4,
 
-	SKB_GSO_FCOE = 1 << 5,
+	SKB_GSO_TCPV6 = 1 << 5,
 
-	SKB_GSO_GRE = 1 << 6,
+	SKB_GSO_FCOE = 1 << 6,
 
-	SKB_GSO_GRE_CSUM = 1 << 7,
+	SKB_GSO_GRE = 1 << 7,
 
-	SKB_GSO_IPIP = 1 << 8,
+	SKB_GSO_GRE_CSUM = 1 << 8,
 
-	SKB_GSO_SIT = 1 << 9,
+	SKB_GSO_IPIP = 1 << 9,
 
-	SKB_GSO_UDP_TUNNEL = 1 << 10,
+	SKB_GSO_SIT = 1 << 10,
 
-	SKB_GSO_UDP_TUNNEL_CSUM = 1 << 11,
+	SKB_GSO_UDP_TUNNEL = 1 << 11,
 
-	SKB_GSO_TUNNEL_REMCSUM = 1 << 12,
+	SKB_GSO_UDP_TUNNEL_CSUM = 1 << 12,
+
+	SKB_GSO_TUNNEL_REMCSUM = 1 << 13,
 };
 
 #if BITS_PER_LONG > 32