datapath: Use upstream ipv6_find_hdr().

ipv6_find_hdr() already fixed in newer upstram kernel by Ansis, we
can start using this API safely.
This patch also backports fix (ipv6: ipv6_find_hdr restore prev
functionality) to compat ipv6_find_hdr().

CC: Ansis Atteka <aatteka@nicira.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Andy Zhou <azhou@nicira.com>

acinclude.m4

@@ -364,6 +364,7 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
   OVS_GREP_IFELSE([$KSRC/include/net/gre.h], [gre_handle_offloads])
   OVS_GREP_IFELSE([$KSRC/include/net/ip_tunnels.h], [iptunnel_xmit.*net],
                   [OVS_DEFINE([HAVE_IPTUNNEL_XMIT_NET])])
+  OVS_GREP_IFELSE([$KSRC/include/net/ipv6.h], [IP6_FH_F_SKIP_RH])
   OVS_GREP_IFELSE([$KSRC/include/net/netlink.h], [nla_get_be16])
   OVS_GREP_IFELSE([$KSRC/include/net/netlink.h], [nla_put_be16])
   OVS_GREP_IFELSE([$KSRC/include/net/netlink.h], [nla_put_be32])

datapath/actions.c

@@ -482,7 +482,7 @@ static int set_ipv6(struct sk_buff *skb, struct sw_flow_key *key,
 
 	if (memcmp(ipv6_key->ipv6_dst, daddr, sizeof(ipv6_key->ipv6_dst))) {
 		unsigned int offset = 0;
-		int flags = OVS_IP6T_FH_F_SKIP_RH;
+		int flags = IP6_FH_F_SKIP_RH;
 		bool recalc_csum = true;
 
 		if (ipv6_ext_hdr(nh->nexthdr))

datapath/linux/compat/exthdrs_core.c

@@ -2,6 +2,7 @@
 #include <linux/version.h>
 #include <net/ipv6.h>
 
+#ifndef HAVE_IP6_FH_F_SKIP_RH
 #if LINUX_VERSION_CODE < KERNEL_VERSION(3,3,0)
 int rpl_ipv6_skip_exthdr(const struct sk_buff *skb, int start,
 			 u8 *nexthdrp, __be16 *frag_offp)
@@ -68,9 +69,9 @@ int rpl_ipv6_skip_exthdr(const struct sk_buff *skb, int start,
  * isn't NULL.
  *
  * if flags is not NULL and it's a fragment, then the frag flag
- * OVS_IP6T_FH_F_FRAG will be set. If it's an AH header, the
- * OVS_IP6T_FH_F_AUTH flag is set and target < 0, then this function will
- * stop at the AH header. If OVS_IP6T_FH_F_SKIP_RH flag was passed, then this
+ * IP6_FH_F_FRAG will be set. If it's an AH header, the
+ * IP6_FH_F_AUTH flag is set and target < 0, then this function will
+ * stop at the AH header. If IP6_FH_F_SKIP_RH flag was passed, then this
  * function will skip all those routing headers, where segements_left was 0.
  */
 int rpl_ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
@@ -103,7 +104,7 @@ int rpl_ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
 		found = (nexthdr == target);
 
 		if ((!ipv6_ext_hdr(nexthdr)) || nexthdr == NEXTHDR_NONE) {
-			if (target < 0)
+			if (target < 0 || found)
 				break;
 			return -ENOENT;
 		}
@@ -120,7 +121,7 @@ int rpl_ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
 			if (rh == NULL)
 				return -EBADMSG;
 
-			if (flags && (*flags & OVS_IP6T_FH_F_SKIP_RH) &&
+			if (flags && (*flags & IP6_FH_F_SKIP_RH) &&
 			    rh->segments_left == 0)
 				found = false;
 		}
@@ -130,7 +131,7 @@ int rpl_ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
 			__be16 *fp;
 
 			if (flags)	/* Indicate that this is a fragment */
-				*flags |= OVS_IP6T_FH_F_FRAG;
+				*flags |= IP6_FH_F_FRAG;
 			fp = skb_header_pointer(skb,
 						start+offsetof(struct frag_hdr,
 							       frag_off),
@@ -152,8 +153,7 @@ int rpl_ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
 			}
 			hdrlen = 8;
 		} else if (nexthdr == NEXTHDR_AUTH) {
-			if (flags && (*flags & OVS_IP6T_FH_F_AUTH) &&
-			    (target < 0))
+			if (flags && (*flags & IP6_FH_F_AUTH) && (target < 0))
 				break;
 			hdrlen = (hp->hdrlen + 2) << 2;
 		} else
@@ -169,3 +169,5 @@ int rpl_ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
 	*offset = start;
 	return nexthdr;
 }
+
+#endif

datapath/linux/compat/include/net/ipv6.h

@@ -9,23 +9,28 @@
 #define NEXTHDR_SCTP    132 /* Stream Control Transport Protocol */
 #endif
 
+#ifndef HAVE_IP6_FH_F_SKIP_RH
+
+enum {
+	IP6_FH_F_FRAG           = (1 << 0),
+	IP6_FH_F_AUTH           = (1 << 1),
+	IP6_FH_F_SKIP_RH        = (1 << 2),
+};
+
 #if LINUX_VERSION_CODE < KERNEL_VERSION(3,3,0)
 #define ipv6_skip_exthdr rpl_ipv6_skip_exthdr
 extern int ipv6_skip_exthdr(const struct sk_buff *skb, int start,
 			    u8 *nexthdrp, __be16 *frag_offp);
 #endif
 
-enum {
-	OVS_IP6T_FH_F_FRAG	= (1 << 0),
-	OVS_IP6T_FH_F_AUTH	= (1 << 1),
-	OVS_IP6T_FH_F_SKIP_RH	= (1 << 2),
-};
-
 /* This function is upstream, but not the version which skips routing
- * headers with 0 segments_left. We plan to propose the extended version. */
+ * headers with 0 segments_left. We fixed it when we introduced
+ * IP6_FH_F_SKIP_RH.
+ */
 #define ipv6_find_hdr rpl_ipv6_find_hdr
 extern int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
 			 int target, unsigned short *fragoff, int *fragflg);
+#endif
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(3,6,0)
 static inline u32 ipv6_addr_hash(const struct in6_addr *a)