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authorDavid Ahern <dsa@cumulusnetworks.com>2017-03-11 01:11:39 +0300
committerDavid S. Miller <davem@davemloft.net>2017-03-13 09:45:36 +0300
commit79099aab38c8f5c746748b066ae74ba984fe2cc8 (patch)
treee54955acc8fead5a71eb675516aff2db3173099d /net/mpls/af_mpls.c
parentb17075d5c1988b83f840d272c795ac17d57ce804 (diff)
downloadlinux-79099aab38c8f5c746748b066ae74ba984fe2cc8.tar.xz
mpls: Do not decrement alive counter for unregister events
Multipath routes can be rendered usesless when a device in one of the paths is deleted. For example: $ ip -f mpls ro ls 100 nexthop as to 200 via inet 172.16.2.2 dev virt12 nexthop as to 300 via inet 172.16.3.2 dev br0 101 nexthop as to 201 via inet6 2000:2::2 dev virt12 nexthop as to 301 via inet6 2000:3::2 dev br0 $ ip li del br0 When br0 is deleted the other hop is not considered in mpls_select_multipath because of the alive check -- rt_nhn_alive is 0. rt_nhn_alive is decremented once in mpls_ifdown when the device is taken down (NETDEV_DOWN) and again when it is deleted (NETDEV_UNREGISTER). For a 2 hop route, deleting one device drops the alive count to 0. Since devices are taken down before unregistering, the decrement on NETDEV_UNREGISTER is redundant. Fixes: c89359a42e2a4 ("mpls: support for dead routes") Signed-off-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/mpls/af_mpls.c')
-rw-r--r--net/mpls/af_mpls.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index a1477989ed0b..33211f9a2656 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -1288,7 +1288,8 @@ static void mpls_ifdown(struct net_device *dev, int event)
/* fall through */
case NETDEV_CHANGE:
nh->nh_flags |= RTNH_F_LINKDOWN;
- ACCESS_ONCE(rt->rt_nhn_alive) = rt->rt_nhn_alive - 1;
+ if (event != NETDEV_UNREGISTER)
+ ACCESS_ONCE(rt->rt_nhn_alive) = rt->rt_nhn_alive - 1;
break;
}
if (event == NETDEV_UNREGISTER)