Commit 1dbe3252 authored by Wei Wang's avatar Wei Wang Committed by David S. Miller
Browse files

net: use loopback dev when generating blackhole route 



Existing ipv4/6_blackhole_route() code generates a blackhole route
with dst->dev pointing to the passed in dst->dev.
It is not necessary to hold reference to the passed in dst->dev
because the packets going through this route are dropped anyway.
A loopback interface is good enough so that we don't need to worry about
releasing this dst->dev when this dev is going down.

Signed-off-by: default avatarWei Wang <weiwan@google.com>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d24406c8

net/ipv4/route.c

+1 −1
Original line number Diff line number Diff line
@@ -2504,7 +2504,7 @@ struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_or 
		new->input = dst_discard;

		new->output = dst_discard_out;



		new->dev = ort->dst.dev;

		new->dev = net->loopback_dev;

		if (new->dev)

			dev_hold(new->dev);

net/ipv6/route.c

+5 −4
Original line number Diff line number Diff line
@@ -1245,9 +1245,12 @@ EXPORT_SYMBOL_GPL(ip6_route_output_flags); 
struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_orig)

{

	struct rt6_info *rt, *ort = (struct rt6_info *) dst_orig;

	struct net_device *loopback_dev = net->loopback_dev;

	struct dst_entry *new = NULL;



	rt = dst_alloc(&ip6_dst_blackhole_ops, ort->dst.dev, 1, DST_OBSOLETE_NONE, 0);



	rt = dst_alloc(&ip6_dst_blackhole_ops, loopback_dev, 1,

		       DST_OBSOLETE_NONE, 0);

	if (rt) {

		rt6_info_init(rt);
@@ -1257,10 +1260,8 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori 
		new->output = dst_discard_out;



		dst_copy_metrics(new, &ort->dst);

		rt->rt6i_idev = ort->rt6i_idev;

		if (rt->rt6i_idev)

			in6_dev_hold(rt->rt6i_idev);



		rt->rt6i_idev = in6_dev_get(loopback_dev);

		rt->rt6i_gateway = ort->rt6i_gateway;

		rt->rt6i_flags = ort->rt6i_flags & ~RTF_PCPU;

		rt->rt6i_metric = 0;

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