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/core/dst.c b/net/core/dst.c
index 07bacff84aa4..069d51d29414 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -94,7 +94,7 @@ loop:
                          * But we do not have state "obsoleted, but
                          * referenced by parent", so it is right.
                          */
-                        if (dst->obsolete > 1)
+                        if (dst->obsolete > 0)
                                 continue;
 
                         ___dst_free(dst);
@@ -202,7 +202,7 @@ static void ___dst_free(struct dst_entry *dst)
          */
         if (dst->dev == NULL || !(dst->dev->flags&IFF_UP))
                 dst->input = dst->output = dst_discard;
-        dst->obsolete = 2;
+        dst->obsolete = DST_OBSOLETE_DEAD;
 }
 
 void __dst_free(struct dst_entry *dst)