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>
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 65bd1ca5..c5a5165 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1350,7 +1350,7 @@
default:
BUG();
}
- xdst = dst_alloc(dst_ops, NULL, 0, 0, 0);
+ xdst = dst_alloc(dst_ops, NULL, 0, DST_OBSOLETE_NONE, 0);
if (likely(xdst)) {
struct dst_entry *dst = &xdst->u.dst;
@@ -1477,7 +1477,7 @@
dst1->xfrm = xfrm[i];
xdst->xfrm_genid = xfrm[i]->genid;
- dst1->obsolete = -1;
+ dst1->obsolete = DST_OBSOLETE_FORCE_CHK;
dst1->flags |= DST_HOST;
dst1->lastuse = now;
@@ -2219,12 +2219,13 @@
static struct dst_entry *xfrm_dst_check(struct dst_entry *dst, u32 cookie)
{
/* Code (such as __xfrm4_bundle_create()) sets dst->obsolete
- * to "-1" to force all XFRM destinations to get validated by
- * dst_ops->check on every use. We do this because when a
- * normal route referenced by an XFRM dst is obsoleted we do
- * not go looking around for all parent referencing XFRM dsts
- * so that we can invalidate them. It is just too much work.
- * Instead we make the checks here on every use. For example:
+ * to DST_OBSOLETE_FORCE_CHK to force all XFRM destinations to
+ * get validated by dst_ops->check on every use. We do this
+ * because when a normal route referenced by an XFRM dst is
+ * obsoleted we do not go looking around for all parent
+ * referencing XFRM dsts so that we can invalidate them. It
+ * is just too much work. Instead we make the checks here on
+ * every use. For example:
*
* XFRM dst A --> IPv4 dst X
*
@@ -2234,9 +2235,9 @@
* stale_bundle() check.
*
* When a policy's bundle is pruned, we dst_free() the XFRM
- * dst which causes it's ->obsolete field to be set to a
- * positive non-zero integer. If an XFRM dst has been pruned
- * like this, we want to force a new route lookup.
+ * dst which causes it's ->obsolete field to be set to
+ * DST_OBSOLETE_DEAD. If an XFRM dst has been pruned like
+ * this, we want to force a new route lookup.
*/
if (dst->obsolete < 0 && !stale_bundle(dst))
return dst;