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net: use loopback dev when generating blackhole route

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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: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wei Wang 2017-06-17 10:42:26 -07:00 committed by David S. Miller
parent d24406c85d
commit 1dbe32525e
2 changed files with 6 additions and 5 deletions
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2
net/ipv4/route.c
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@ -2504,7 +2504,7 @@ struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_or
new->input = dst_discard; new->input = dst_discard;
new->output = dst_discard_out; new->output = dst_discard_out;
new->dev = ort->dst.dev; new->dev = net->loopback_dev;
if (new->dev) if (new->dev)
dev_hold(new->dev); dev_hold(new->dev);

9
net/ipv6/route.c
View File

@ -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 dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_orig)
{ {
struct rt6_info *rt, *ort = (struct rt6_info *) 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; 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) { if (rt) {
rt6_info_init(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; new->output = dst_discard_out;
dst_copy_metrics(new, &ort->dst); 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_gateway = ort->rt6i_gateway;
rt->rt6i_flags = ort->rt6i_flags & ~RTF_PCPU; rt->rt6i_flags = ort->rt6i_flags & ~RTF_PCPU;
rt->rt6i_metric = 0; rt->rt6i_metric = 0;