From 0259e9e0e05e217095e7501f31638053f3f6301d Mon Sep 17 00:00:00 2001
From: Octavian Purdila <opurdila@ixiacom.com>
Date: Fri, 2 Oct 2009 11:39:15 +0000
Subject: [PATCH] --- yaml --- r: 170464 b: refs/heads/master c:
 f7734fdf61ec6bb848e0bafc1fb8bad2c124bb50 h: refs/heads/master v: v3

---
 [refs]                                       |  2 +-
 trunk/Documentation/networking/ip-sysctl.txt | 18 ++++++++++++++++++
 trunk/include/linux/ipv6.h                   |  1 +
 trunk/net/ipv6/addrconf.c                    |  8 ++++++++
 trunk/net/ipv6/ndisc.c                       |  1 +
 5 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index f9b691367fbe..8e44ad9ddeb1 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 51953d5bc43e468f24cc573a45cde1d32af129b8
+refs/heads/master: f7734fdf61ec6bb848e0bafc1fb8bad2c124bb50
diff --git a/trunk/Documentation/networking/ip-sysctl.txt b/trunk/Documentation/networking/ip-sysctl.txt
index fbe427a6580c..a0e134dd2523 100644
--- a/trunk/Documentation/networking/ip-sysctl.txt
+++ b/trunk/Documentation/networking/ip-sysctl.txt
@@ -1086,6 +1086,24 @@ accept_dad - INTEGER
 	2: Enable DAD, and disable IPv6 operation if MAC-based duplicate
 	   link-local address has been found.
 
+force_tllao - BOOLEAN
+	Enable sending the target link-layer address option even when
+	responding to a unicast neighbor solicitation.
+	Default: FALSE
+
+	Quoting from RFC 2461, section 4.4, Target link-layer address:
+
+	"The option MUST be included for multicast solicitations in order to
+	avoid infinite Neighbor Solicitation "recursion" when the peer node
+	does not have a cache entry to return a Neighbor Advertisements
+	message.  When responding to unicast solicitations, the option can be
+	omitted since the sender of the solicitation has the correct link-
+	layer address; otherwise it would not have be able to send the unicast
+	solicitation in the first place. However, including the link-layer
+	address in this case adds little overhead and eliminates a potential
+	race condition where the sender deletes the cached link-layer address
+	prior to receiving a response to a previous solicitation."
+
 icmp/*:
 ratelimit - INTEGER
 	Limit the maximal rates for sending ICMPv6 packets.
diff --git a/trunk/include/linux/ipv6.h b/trunk/include/linux/ipv6.h
index c662efa68289..ae74ede1abe7 100644
--- a/trunk/include/linux/ipv6.h
+++ b/trunk/include/linux/ipv6.h
@@ -167,6 +167,7 @@ struct ipv6_devconf {
 #endif
 	__s32		disable_ipv6;
 	__s32		accept_dad;
+	__s32		force_tllao;
 	void		*sysctl;
 };
 
diff --git a/trunk/net/ipv6/addrconf.c b/trunk/net/ipv6/addrconf.c
index 1fd0a3d775d2..bdcee6981c60 100644
--- a/trunk/net/ipv6/addrconf.c
+++ b/trunk/net/ipv6/addrconf.c
@@ -4352,6 +4352,14 @@ static struct addrconf_sysctl_table
 			.mode		=	0644,
 			.proc_handler	=	proc_dointvec,
 		},
+		{
+			.ctl_name       = CTL_UNNUMBERED,
+			.procname       = "force_tllao",
+			.data           = &ipv6_devconf.force_tllao,
+			.maxlen         = sizeof(int),
+			.mode           = 0644,
+			.proc_handler   = proc_dointvec
+		},
 		{
 			.ctl_name	=	0,	/* sentinel */
 		}
diff --git a/trunk/net/ipv6/ndisc.c b/trunk/net/ipv6/ndisc.c
index f74e4e2cdd06..3507cfe1e7a2 100644
--- a/trunk/net/ipv6/ndisc.c
+++ b/trunk/net/ipv6/ndisc.c
@@ -598,6 +598,7 @@ static void ndisc_send_na(struct net_device *dev, struct neighbour *neigh,
 	icmp6h.icmp6_solicited = solicited;
 	icmp6h.icmp6_override = override;
 
+	inc_opt |= ifp->idev->cnf.force_tllao;
 	__ndisc_send(dev, neigh, daddr, src_addr,
 		     &icmp6h, solicited_addr,
 		     inc_opt ? ND_OPT_TARGET_LL_ADDR : 0);