commit 36e566f9ed455961014662439bd1e7699e13e2b4
Author: Ryota Ozaki <ozaki-r@iij.ad.jp>
Date:   Wed May 27 12:23:57 2015 +0900

    Use a mtag instead of a mbuf flag for MPLS fixup

diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index 2b7a9ae..8327213 100644
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -353,9 +353,14 @@ ether_output(struct ifnet * const ifp0, struct mbuf * const m0,
 	}
 
 #ifdef MPLS
-	if ((m->m_flags & M_MPLS) != 0) {
-		etype = htons(ETHERTYPE_MPLS);
-		m->m_flags &= ~M_MPLS;
+	{
+		struct m_tag *mtag;
+		mtag = m_tag_find(m, PACKET_TAG_MPLS, NULL);
+		if (mtag != NULL) {
+			/* Having the tag itself indicates it's MPLS */
+			etype = htons(ETHERTYPE_MPLS);
+			m_tag_delete(m, mtag);
+		}
 	}
 #endif
 
diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c
index 84e7f63..7d8786f 100644
--- a/sys/netinet/ip_output.c
+++ b/sys/netinet/ip_output.c
@@ -276,11 +276,25 @@ out:
 #ifdef MPLS
 	if (rt0 != NULL && rt_gettag(rt0) != NULL &&
 	    rt_gettag(rt0)->sa_family == AF_MPLS &&
-	    (m->m_flags & (M_MCAST | M_BCAST)) == 0) {
+	    (m->m_flags & (M_MCAST | M_BCAST)) == 0 &&
+	    ifp->if_type == IFT_ETHER) {
 		union mpls_shim msh;
 		msh.s_addr = MPLS_GETSADDR(rt0);
-		if (msh.shim.label != MPLS_LABEL_IMPLNULL)
-			m->m_flags |= M_MPLS;
+		if (msh.shim.label != MPLS_LABEL_IMPLNULL) {
+			struct m_tag *mtag;
+			/*
+			 * XXX tentative solution to tell ether_output
+			 * it's MPLS. Need some more efficient solution.
+			 */
+			mtag = m_tag_get(PACKET_TAG_MPLS,
+			    sizeof(int) /* dummy */,
+			    M_NOWAIT);
+			if (mtag == NULL) {
+				error = ENOMEM;
+				goto bad;
+			}
+			m_tag_prepend(m, mtag);
+		}
 	}
 #endif
 
diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 6fe6fc3..c907bdd 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -351,8 +351,6 @@ MBUF_DEFINE(mbuf, MHLEN, MLEN);
 #define	M_LINK6		0x00040000	/* link layer specific flag */
 #define	M_LINK7		0x00080000	/* link layer specific flag */
 
-#define	M_MPLS		0x00100000	/* MPLS flag */
-
 /* additional flags for M_EXT mbufs */
 #define	M_EXT_FLAGS	0xff000000
 #define	M_EXT_CLUSTER	0x01000000	/* ext is a cluster */
@@ -915,6 +913,8 @@ struct	m_tag *m_tag_next(struct mbuf *, struct m_tag *);
 						    * loop detection/recovery
 						    */
 
+#define	PACKET_TAG_MPLS				29 /* Indicate it's for MPLS */
+
 /*
  * Return the number of bytes in the mbuf chain, m.
  */