From 1dbe32525e26ec28d2cc17f65a90fc7b53f1f8d0 Mon Sep 17 00:00:00 2001 From: Wei Wang Date: Sat, 17 Jun 2017 10:42:26 -0700 Subject: [PATCH] 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: Wei Wang Acked-by: Martin KaFai Lau Signed-off-by: David S. Miller --- net/ipv4/route.c | 2 +- net/ipv6/route.c | 9 +++++---- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 9b38cf18144e..0a843ef2b709 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -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); diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 18fe6e2b88d5..bc1bc91bb969 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -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; -- 2.20.1