ospf6d: break early on route prefix mismatch

The route linked list in ospf6d is ordered in prefix batches which
are associated with a the route node denoting the prefix. So if
you look up the prefix in the tree and start walking the list, if you
find a prefix which differs from the one you are interested in then
you have gone beyond the batch of routes for that prefix.

In some cases the route database linked list is used on a per-prefix
basis. The existing code simply does a continue when the prefix does
not match and continues to walk. This works with small numbers of
routes because the walk continues through unrelated prefix batches and
never finds anything to operate on. However if we have many thousands
of routes these walks become expensive and can cause the SPF thread
(amongst others) to run very long, causing issues with adjacencies
where the dead timer is short.

Add a break to these prefix-based loops to exit early if we get a
prefix mismatch to avoid continuing down the route list if we have
overshot.

Signed-off-by: Pat Ruddy <pat@voltanet.io>

diff --git a/ospf6d/ospf6_abr.c b/ospf6d/ospf6_abr.c
index f289bf26b933279eb71250b2770d3b50bfb56296..08d2ef0702da3d8c3b6f697eb733ff1f26c8a549 100644 (file)
--- a/ospf6d/ospf6_abr.c
+++ b/ospf6d/ospf6_abr.c
@@ -1194,9 +1194,16 @@ void ospf6_abr_examin_summary(struct ospf6_lsa *lsa, struct ospf6_area *oa)
                                   __func__, &prefix, listcount(old->paths));
        }
        for (old_route = old; old_route; old_route = old_route->next) {
-               if (!ospf6_route_is_same(old_route, route) ||
-                       (old_route->type != route->type) ||
-                       (old_route->path.type != route->path.type))
+
+               /* The route linked-list is grouped in batches of prefix.
+                * If the new prefix is not the same as the one of interest
+                * then we have walked over the end of the batch and so we
+                * should break rather than continuing unnecessarily.
+                */
+               if (!ospf6_route_is_same(old_route, route))
+                       break;
+               if ((old_route->type != route->type)
+                   || (old_route->path.type != route->path.type))
                        continue;
 
                if ((ospf6_route_cmp(route, old_route) != 0)) {

diff --git a/ospf6d/ospf6_asbr.c b/ospf6d/ospf6_asbr.c
index 3e911a743a6813c68cfb25df3a1d1b9b9d6bb32c..2b1c344ba8c7392586618a3a4726521783b87fc6 100644 (file)
--- a/ospf6d/ospf6_asbr.c
+++ b/ospf6d/ospf6_asbr.c
@@ -240,8 +240,14 @@ void ospf6_asbr_update_route_ecmp_path(struct ospf6_route *old,
 
                next_route = old_route->next;
 
-               if (!ospf6_route_is_same(old_route, route)
-                   || (old_route->path.type != route->path.type))
+               /* The route linked-list is grouped in batches of prefix.
+                * If the new prefix is not the same as the one of interest
+                * then we have walked over the end of the batch and so we
+                * should break rather than continuing unnecessarily.
+                */
+               if (!ospf6_route_is_same(old_route, route))
+                       break;
+               if (old_route->path.type != route->path.type)
                        continue;
 
                /* Current and New route has same origin,
@@ -345,11 +351,14 @@ void ospf6_asbr_update_route_ecmp_path(struct ospf6_route *old,
        /* Add new route */
        for (old_route = old; old_route; old_route = old_route->next) {
 
-               /* Current and New Route prefix or route type
-                * is not same skip this current node.
+               /* The route linked-list is grouped in batches of prefix.
+                * If the new prefix is not the same as the one of interest
+                * then we have walked over the end of the batch and so we
+                * should break rather than continuing unnecessarily.
                 */
-               if (!ospf6_route_is_same(old_route, route)
-                   || (old_route->path.type != route->path.type))
+               if (!ospf6_route_is_same(old_route, route))
+                       break;
+               if (old_route->path.type != route->path.type)
                        continue;
 
                /* Old Route and New Route have Equal Cost, Merge NHs */

diff --git a/ospf6d/ospf6_intra.c b/ospf6d/ospf6_intra.c
index c971c6180e8536cfe5e6889d27869b8e43909266..69ebc112a71563ad1bf29a55139c1dc7a11617c0 100644 (file)
--- a/ospf6d/ospf6_intra.c
+++ b/ospf6d/ospf6_intra.c
@@ -1490,8 +1490,14 @@ void ospf6_intra_prefix_route_ecmp_path(struct ospf6_area *oa,
        for (old_route = old; old_route; old_route = old_route->next) {
                bool route_updated = false;
 
-               if (!ospf6_route_is_same(old_route, route) ||
-                       (old_route->path.type != route->path.type))
+               /* The route linked-list is grouped in batches of prefix.
+                * If the new prefix is not the same as the one of interest
+                * then we have walked over the end of the batch and so we
+                * should break rather than continuing unnecessarily.
+                */
+               if (!ospf6_route_is_same(old_route, route))
+                       break;
+               if (old_route->path.type != route->path.type)
                        continue;
 
                /* Current and New route has same origin,
@@ -1589,8 +1595,14 @@ void ospf6_intra_prefix_route_ecmp_path(struct ospf6_area *oa,
 
        for (old_route = old; old_route; old_route = old_route->next) {
 
-               if (!ospf6_route_is_same(old_route, route) ||
-                       (old_route->path.type != route->path.type))
+               /* The route linked-list is grouped in batches of prefix.
+                * If the new prefix is not the same as the one of interest
+                * then we have walked over the end of the batch and so we
+                * should break rather than continuing unnecessarily.
+                */
+               if (!ospf6_route_is_same(old_route, route))
+                       break;
+               if (old_route->path.type != route->path.type)
                        continue;
 
                /* Old Route and New Route have Equal Cost, Merge NHs */