netdev - [PATCH net-next 1/2] net: mpls: Don't show nexthop if device has been deleted

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Date:   Fri, 24 Mar 2017 15:21:56 -0700
From:   David Ahern <dsa@...ulusnetworks.com>
To:     netdev@...r.kernel.org
Cc:     rshearma@...cade.com, roopa@...ulusnetworks.com,
        David Ahern <dsa@...ulusnetworks.com>
Subject: [PATCH net-next 1/2] net: mpls: Don't show nexthop if device has been deleted

If the device for a nexthop in a multipath route is deleted, the nexthop
is effectively removed from the route. Currently, a route dump still
returns the nexhop though without the device set:

$ ip -f mpls ro ls
100
	nexthopvia inet 10.11.1.2  dev br0
	nexthopvia inet 10.100.3.1  dev eth3
$ ip li del br0
$ ip -f mpls ro ls
100
	nexthopvia inet 10.11.1.2  dev * dead linkdown
	nexthopvia inet 10.100.3.1  dev eth3

Since the nexthop is effectively deleted, drop the hop from the route
dump.

Signed-off-by: David Ahern <dsa@...ulusnetworks.com>
---
 net/mpls/af_mpls.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index cd8be8d5e4ad..3861f8dfa9c1 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -1769,13 +1769,15 @@ static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
 			goto nla_put_failure;
 
 		for_nexthops(rt) {
+			dev = rtnl_dereference(nh->nh_dev);
+			if (!dev)
+				continue;
+
 			rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
 			if (!rtnh)
 				goto nla_put_failure;
 
-			dev = rtnl_dereference(nh->nh_dev);
-			if (dev)
-				rtnh->rtnh_ifindex = dev->ifindex;
+			rtnh->rtnh_ifindex = dev->ifindex;
 			if (nh->nh_flags & RTNH_F_LINKDOWN) {
 				rtnh->rtnh_flags |= RTNH_F_LINKDOWN;
 				linkdown++;
-- 
2.1.4