net: Document dst->obsolete better.

Add a big comment explaining how the field works, and use defines
instead of magic constants for the values assigned to it.

Suggested by Joe Perches.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 84f6564dd372..cf02cb97bbdd 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -281,7 +281,7 @@ static inline struct rt6_info *ip6_dst_alloc(struct net *net,
                                              struct fib6_table *table)
 {
         struct rt6_info *rt = dst_alloc(&net->ipv6.ip6_dst_ops, dev,
-                                        0, 0, flags);
+                                        0, DST_OBSOLETE_NONE, flags);
 
         if (rt) {
                 struct dst_entry *dst = &rt->dst;
@@ -985,7 +985,7 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori
         struct rt6_info *rt, *ort = (struct rt6_info *) dst_orig;
         struct dst_entry *new = NULL;
 
-        rt = dst_alloc(&ip6_dst_blackhole_ops, ort->dst.dev, 1, 0, 0);
+        rt = dst_alloc(&ip6_dst_blackhole_ops, ort->dst.dev, 1, DST_OBSOLETE_NONE, 0);
         if (rt) {
                 new = &rt->dst;