[PATCH 3.19.y-ckt 081/102] ip6_gre: release cached dst on tunnel removal

[Kamal Mostafa]

3.19.8-ckt7 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: huaibin Wang <huaibin.wang at 6wind.com>

commit d4257295ba1b389c693b79de857a96e4b7cd8ac0 upstream.

When a tunnel is deleted, the cached dst entry should be released.

This problem may prevent the removal of a netns (seen with a x-netns IPv6
gre tunnel):
  unregister_netdevice: waiting for lo to become free. Usage count = 3

CC: Dmitry Kozlov <xeb at mail.ru>
Fixes: c12b395a4664 ("gre: Support GRE over IPv6")
Signed-off-by: huaibin Wang <huaibin.wang at 6wind.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel at 6wind.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/ipv6/ip6_gre.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 01ccc28..d1b83a3 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -361,6 +361,7 @@ static void ip6gre_tunnel_uninit(struct net_device *dev)
 	struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id);
 
 	ip6gre_tunnel_unlink(ign, t);
+	ip6_tnl_dst_reset(t);
 	dev_put(dev);
 }
 
-- 
1.9.1