Fix FIB recursion loops via cover (VPP-842)
Change-Id: Ia91c3e8cb27b9e4c1cccefc0a4857dd9995450ab
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/src/vnet/fib/fib_entry_src_rr.c b/src/vnet/fib/fib_entry_src_rr.c
index c145aaa..d66ef7b 100644
--- a/src/vnet/fib/fib_entry_src_rr.c
+++ b/src/vnet/fib/fib_entry_src_rr.c
@@ -69,6 +69,47 @@
src->rr.fesr_sibling = FIB_NODE_INDEX_INVALID;
}
+
+/*
+ * use the path-list of the cover, unless it would form a loop.
+ * that is unless the cover is via this entry.
+ * If a loop were to form it would be a 1 level loop (i.e. X via X),
+ * and there would be 2 locks on the path-list; one since its used
+ * by the cover, and 1 from here. The first lock will go when the
+ * cover is removed, the second, and last, when the covered walk
+ * occurs during the cover's removel - this is not a place where
+ * we can handle last lock gone.
+ * In short, don't let the loop form. The usual rules of 'we must
+ * let it form so we know when it breaks' don't apply here, since
+ * the loop will break when the cover changes, and this function
+ * will be called again when that happens.
+ */
+static void
+fib_entry_src_rr_use_covers_pl (fib_entry_src_t *src,
+ const fib_entry_t *fib_entry,
+ const fib_entry_t *cover)
+{
+ fib_node_index_t *entries = NULL;
+ fib_protocol_t proto;
+
+ proto = fib_entry->fe_prefix.fp_proto;
+ vec_add1(entries, fib_entry_get_index(fib_entry));
+
+ if (fib_path_list_recursive_loop_detect(cover->fe_parent,
+ &entries))
+ {
+ src->fes_pl = fib_path_list_create_special(
+ proto,
+ FIB_PATH_LIST_FLAG_DROP,
+ drop_dpo_get(fib_proto_to_dpo(proto)));
+ }
+ else
+ {
+ src->fes_pl = cover->fe_parent;
+ }
+ vec_free(entries);
+}
+
/*
* Source activation. Called when the source is the new best source on the entry
*/
@@ -112,40 +153,7 @@
}
else
{
- /*
- * use the path-list of the cover, unless it would form a loop.
- * that is unless the cover is via this entry.
- * If a loop were to form it would be a 1 level loop (i.e. X via X),
- * and there would be 2 locks on the path-list; one since its used
- * by the cover, and 1 from here. The first lock will go when the
- * cover is removed, the second, and last, when the covered walk
- * occurs during the cover's removel - this is not a place where
- * we can handle last lock gone.
- * In short, don't let the loop form. The usual rules of 'we must
- * let it form so we know when it breaks' don't apply here, since
- * the loop will break when the cover changes, and this function
- * will be called again when that happens.
- */
- fib_node_index_t *entries = NULL;
- fib_protocol_t proto;
-
- proto = fib_entry->fe_prefix.fp_proto;
- vec_add1(entries, fib_entry_get_index(fib_entry));
-
- if (fib_path_list_recursive_loop_detect(cover->fe_parent,
- &entries))
- {
- src->fes_pl = fib_path_list_create_special(
- proto,
- FIB_PATH_LIST_FLAG_DROP,
- drop_dpo_get(fib_proto_to_dpo(proto)));
- }
- else
- {
- src->fes_pl = cover->fe_parent;
- }
- vec_free(entries);
-
+ fib_entry_src_rr_use_covers_pl(src, fib_entry, cover);
}
fib_path_list_lock(src->fes_pl);
@@ -256,7 +264,7 @@
}
else
{
- src->fes_pl = cover->fe_parent;
+ fib_entry_src_rr_use_covers_pl(src, fib_entry, cover);
}
fib_path_list_lock(src->fes_pl);
fib_path_list_unlock(old_path_list);