[ovs-dev] [PATCH 1/6] datapath: Remove support for Don't Fragment inheritance.

[Jesse Gross]

Inheritance of the Don't Fragment bit in tunnels will not be
supported with flow based tunneling and has already been removed
from userspace.  This removes the corresponding kernel support.

Signed-off-by: Jesse Gross <jesse at nicira.com>
---
 datapath/tunnel.c            |    8 +-------
 datapath/tunnel.h            |    3 +--
 include/openvswitch/tunnel.h |    2 +-
 lib/netdev-vport.c           |    6 +-----
 4 files changed, 4 insertions(+), 15 deletions(-)

diff --git a/datapath/tunnel.c b/datapath/tunnel.c
index d03b708..d39f40b 100644
--- a/datapath/tunnel.c
+++ b/datapath/tunnel.c
@@ -627,19 +627,16 @@ static bool check_mtu(struct sk_buff *skb,
 		      const struct rtable *rt, __be16 *frag_offp,
 		      int tunnel_hlen)
 {
-	bool df_inherit;
 	bool pmtud;
 	__be16 frag_off;
 	int mtu = 0;
 	unsigned int packet_length = skb->len - ETH_HLEN;
 
 	if (OVS_CB(skb)->tun_key->ipv4_dst) {
-		df_inherit = false;
 		pmtud = false;
 		frag_off = OVS_CB(skb)->tun_key->tun_flags & OVS_TNL_F_DONT_FRAGMENT ?
 				  htons(IP_DF) : 0;
 	} else {
-		df_inherit = mutable->flags & TNL_F_DF_INHERIT;
 		pmtud = mutable->flags & TNL_F_PMTUD;
 		frag_off = mutable->flags & TNL_F_DF_DEFAULT ? htons(IP_DF) : 0;
 	}
@@ -668,9 +665,6 @@ static bool check_mtu(struct sk_buff *skb,
 	if (skb->protocol == htons(ETH_P_IP)) {
 		struct iphdr *iph = ip_hdr(skb);
 
-		if (df_inherit)
-			frag_off = iph->frag_off & htons(IP_DF);
-
 		if (pmtud && iph->frag_off & htons(IP_DF)) {
 			mtu = max(mtu, IP_MIN_MTU);
 
@@ -684,7 +678,7 @@ static bool check_mtu(struct sk_buff *skb,
 		/* IPv6 requires end hosts to do fragmentation
 		 * if the packet is above the minimum MTU.
 		 */
-		if (df_inherit && packet_length > IPV6_MIN_MTU)
+		if (packet_length > IPV6_MIN_MTU)
 			frag_off = htons(IP_DF);
 
 		if (pmtud) {
diff --git a/datapath/tunnel.h b/datapath/tunnel.h
index b7de7a9..91f5f72 100644
--- a/datapath/tunnel.h
+++ b/datapath/tunnel.h
@@ -56,8 +56,7 @@
 
 /* All public tunnel flags. */
 #define TNL_F_PUBLIC (TNL_F_CSUM | TNL_F_TOS_INHERIT | TNL_F_TTL_INHERIT | \
-		      TNL_F_DF_INHERIT | TNL_F_DF_DEFAULT | TNL_F_PMTUD | \
-		      TNL_F_IPSEC)
+		      TNL_F_DF_DEFAULT | TNL_F_PMTUD | TNL_F_IPSEC)
 
 /**
  * struct port_lookup_key - Tunnel port key, used as hash table key.
diff --git a/include/openvswitch/tunnel.h b/include/openvswitch/tunnel.h
index 8a53ef8..6eb01b8 100644
--- a/include/openvswitch/tunnel.h
+++ b/include/openvswitch/tunnel.h
@@ -67,7 +67,7 @@ enum {
 #define TNL_F_CSUM		(1 << 0) /* Checksum packets. */
 #define TNL_F_TOS_INHERIT	(1 << 1) /* Inherit ToS from inner packet. */
 #define TNL_F_TTL_INHERIT	(1 << 2) /* Inherit TTL from inner packet. */
-#define TNL_F_DF_INHERIT	(1 << 3) /* Inherit DF bit from inner packet. */
+/* Bit 3 was previously used for Don't Fragment inheritance. " */
 #define TNL_F_DF_DEFAULT	(1 << 4) /* Set DF bit if inherit off or
 					  * not IP. */
 /* Bit 6 is reserved since it was previously used for Tunnel header caching. */
diff --git a/lib/netdev-vport.c b/lib/netdev-vport.c
index cd6ae54..e52557f 100644
--- a/lib/netdev-vport.c
+++ b/lib/netdev-vport.c
@@ -747,11 +747,7 @@ get_tunnel_config(struct netdev_dev *dev_, struct smap *args)
     if (flags & TNL_F_CSUM) {
         smap_add(args, "csum", "true");
     }
-    if (flags & TNL_F_DF_INHERIT) {
-        /* Shouldn't happen as "df_inherit" is no longer supported.  However,
-         * for completeness we report it if it's there. */
-        smap_add(args, "df_inherit", "true");
-    }
+
     if (!(flags & TNL_F_DF_DEFAULT)) {
         smap_add(args, "df_default", "false");
     }
-- 
1.7.9.5