Merge branch 'nexthop-blackhole'

Ido Schimmel says:

====================
nexthop: Do not flush blackhole nexthops when loopback goes down

Patch #1 prevents blackhole nexthops from being flushed when the
loopback device goes down given that as far as user space is concerned,
these nexthops do not have a nexthop device.

Patch #2 adds a test case.

There are no regressions in fib_nexthops.sh with this change:

 # ./fib_nexthops.sh
 ...
 Tests passed: 165
 Tests failed:   0
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/nexthop.c

@@ -1399,7 +1399,7 @@ static int insert_nexthop(struct net *net, struct nexthop *new_nh,
 
 /* rtnl */
 /* remove all nexthops tied to a device being deleted */
-static void nexthop_flush_dev(struct net_device *dev)
+static void nexthop_flush_dev(struct net_device *dev, unsigned long event)
 {
 	unsigned int hash = nh_dev_hashfn(dev->ifindex);
 	struct net *net = dev_net(dev);
@@ -1411,6 +1411,10 @@ static void nexthop_flush_dev(struct net_device *dev)
 		if (nhi->fib_nhc.nhc_dev != dev)
 			continue;
 
+		if (nhi->reject_nh &&
+		    (event == NETDEV_DOWN || event == NETDEV_CHANGE))
+			continue;
+
 		remove_nexthop(net, nhi->nh_parent, NULL);
 	}
 }
@@ -2189,11 +2193,11 @@ static int nh_netdev_event(struct notifier_block *this,
 	switch (event) {
 	case NETDEV_DOWN:
 	case NETDEV_UNREGISTER:
-		nexthop_flush_dev(dev);
+		nexthop_flush_dev(dev, event);
 		break;
 	case NETDEV_CHANGE:
 		if (!(dev_get_flags(dev) & (IFF_RUNNING | IFF_LOWER_UP)))
-			nexthop_flush_dev(dev);
+			nexthop_flush_dev(dev, event);
 		break;
 	case NETDEV_CHANGEMTU:
 		info_ext = ptr;

tools/testing/selftests/net/fib_nexthops.sh

@@ -1524,6 +1524,14 @@ basic()
 	run_cmd "$IP nexthop replace id 2 blackhole dev veth1"
 	log_test $? 2 "Blackhole nexthop with other attributes"
 
+	# blackhole nexthop should not be affected by the state of the loopback
+	# device
+	run_cmd "$IP link set dev lo down"
+	check_nexthop "id 2" "id 2 blackhole"
+	log_test $? 0 "Blackhole nexthop with loopback device down"
+
+	run_cmd "$IP link set dev lo up"
+
 	#
 	# groups
 	#