tipc: refactor name table translate function

The function tipc_nametbl_translate() function is ugly and hard to
follow. This can be improved somewhat by introducing a stack variable
for holding the publication list to be used and re-ordering the if-
clauses for selection of algorithm.

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 25 insertions, 36 deletions

diff --git a/net/tipc/name_table.c b/net/tipc/name_table.c
index e06c7a8907aa..4bdc580c533b 100644
--- a/net/tipc/name_table.c
+++ b/net/tipc/name_table.c
@@ -399,29 +399,32 @@ struct publication *tipc_nametbl_remove_publ(struct net *net, u32 type,
 /**
  * tipc_nametbl_translate - perform service instance to socket translation
  *
- * On entry, 'destnode' is the search domain used during translation.
+ * On entry, 'dnode' is the search domain used during translation.
  *
  * On exit:
- * - if name translation is deferred to another node/cluster/zone,
- *   leaves 'destnode' unchanged (will be non-zero) and returns 0
- * - if name translation is attempted and succeeds, sets 'destnode'
- *   to publication node and returns port reference (will be non-zero)
- * - if name translation is attempted and fails, sets 'destnode' to 0
- *   and returns 0
+ * - if translation is deferred to another node, leave 'dnode' unchanged and
+ *   return 0
+ * - if translation is attempted and succeeds, set 'dnode' to the publishing
+ *   node and return the published (non-zero) port number
+ * - if translation is attempted and fails, set 'dnode' to 0 and return 0
+ *
+ * Note that for legacy users (node configured with Z.C.N address format) the
+ * 'closest-first' lookup algorithm must be maintained, i.e., if dnode is 0
+ * we must look in the local binding list first
  */
-u32 tipc_nametbl_translate(struct net *net, u32 type, u32 instance,
-                           u32 *destnode)
+u32 tipc_nametbl_translate(struct net *net, u32 type, u32 instance, u32 *dnode)
 {
         struct tipc_net *tn = tipc_net(net);
         bool legacy = tn->legacy_addr_format;
         u32 self = tipc_own_addr(net);
         struct service_range *sr;
         struct tipc_service *sc;
+        struct list_head *list;
         struct publication *p;
         u32 port = 0;
         u32 node = 0;
 
-        if (!tipc_in_scope(legacy, *destnode, self))
+        if (!tipc_in_scope(legacy, *dnode, self))
                 return 0;
 
         rcu_read_lock();
@@ -434,43 +437,29 @@ u32 tipc_nametbl_translate(struct net *net, u32 type, u32 instance,
         if (unlikely(!sr))
                 goto no_match;
 
-        /* Closest-First Algorithm */
-        if (legacy && !*destnode) {
-                if (!list_empty(&sr->local_publ)) {
-                        p = list_first_entry(&sr->local_publ,
-                                             struct publication,
-                                             local_publ);
-                        list_move_tail(&p->local_publ,
-                                       &sr->local_publ);
-                } else {
-                        p = list_first_entry(&sr->all_publ,
-                                             struct publication,
-                                             all_publ);
-                        list_move_tail(&p->all_publ,
-                                       &sr->all_publ);
-                }
-        }
-
-        /* Round-Robin Algorithm */
-        else if (*destnode == self) {
-                if (list_empty(&sr->local_publ))
+        /* Select lookup algorithm: local, closest-first or round-robin */
+        if (*dnode == self) {
+                list = &sr->local_publ;
+                if (list_empty(list))
                         goto no_match;
-                p = list_first_entry(&sr->local_publ, struct publication,
-                                     local_publ);
+                p = list_first_entry(list, struct publication, local_publ);
+                list_move_tail(&p->local_publ, &sr->local_publ);
+        } else if (legacy && !*dnode && !list_empty(&sr->local_publ)) {
+                list = &sr->local_publ;
+                p = list_first_entry(list, struct publication, local_publ);
                 list_move_tail(&p->local_publ, &sr->local_publ);
         } else {
-                p = list_first_entry(&sr->all_publ, struct publication,
-                                     all_publ);
+                list = &sr->all_publ;
+                p = list_first_entry(list, struct publication, all_publ);
                 list_move_tail(&p->all_publ, &sr->all_publ);
         }
-
         port = p->port;
         node = p->node;
 no_match:
         spin_unlock_bh(&sc->lock);
 not_found:
         rcu_read_unlock();
-        *destnode = node;
+        *dnode = node;
         return port;
 }