datapath: rhel: Account for RHEL specific backports

The following symbols have been backported to RHEL and the kernel
version is no longer an accurate indicator for their presence:

 - skb_gso_segment
 - netif_skb_features
 - netif_needs_gso

Signed-off-by: Thomas Graf <[email protected]>
Signed-off-by: Jesse Gross <[email protected]>

acinclude.m4

@@ -225,7 +225,10 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
   OVS_GREP_IFELSE([$KSRC/include/linux/netdevice.h], [dev_get_stats])
   OVS_GREP_IFELSE([$KSRC/include/linux/netdevice.h], [dev_get_by_index_rcu])
   OVS_GREP_IFELSE([$KSRC/include/linux/netdevice.h], [__skb_gso_segment])
+  OVS_GREP_IFELSE([$KSRC/include/linux/netdevice.h], [skb_gso_segment])
   OVS_GREP_IFELSE([$KSRC/include/linux/netdevice.h], [can_checksum_protocol])
+  OVS_GREP_IFELSE([$KSRC/include/linux/netdevice.h], [netif_skb_features])
+  OVS_GREP_IFELSE([$KSRC/include/linux/netdevice.h], [netif_needs_gso])
 
   OVS_GREP_IFELSE([$KSRC/include/linux/rcupdate.h], [rcu_read_lock_held], [],
                   [OVS_GREP_IFELSE([$KSRC/include/linux/rtnetlink.h],

datapath/linux/compat/include/linux/netdevice.h

@@ -142,13 +142,17 @@ static inline struct net_device *dev_get_by_index_rcu(struct net *net, int ifind
 #define NETIF_F_V6_CSUM		(NETIF_F_GEN_CSUM | NETIF_F_IPV6_CSUM)
 #endif
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,38)
+#ifndef HAVE_SKB_GSO_SEGMENT
 #define skb_gso_segment rpl_skb_gso_segment
 struct sk_buff *rpl_skb_gso_segment(struct sk_buff *skb, u32 features);
+#endif
 
+#ifndef HAVE_NETIF_SKB_FEATURES
 #define netif_skb_features rpl_netif_skb_features
 u32 rpl_netif_skb_features(struct sk_buff *skb);
+#endif
 
+#ifndef HAVE_NETIF_NEEDS_GSO
 #define netif_needs_gso rpl_netif_needs_gso
 static inline int rpl_netif_needs_gso(struct sk_buff *skb, int features)
 {