Handle rename to existing device

In the case of rename, delete_retain would be called twice. Once
when the interface is removed from the system, and again when
interface is being replaced during rename.

2 files changed, 24 insertions, 16 deletions

diff --git a/lib/if.c b/lib/if.c
index 7c4fb1a4..f15242a2 100644
--- a/lib/if.c
+++ b/lib/if.c
@@ -131,13 +131,14 @@ if_create (const char *name, int namelen)
     ifp->name[namelen] = '\0';
 
     listnode_add_sort (iflist, ifp);
-    ifp->connected = list_new ();
-    ifp->connected->del = (void (*) (void *)) connected_free;
-    
-    if (if_master.if_new_hook)
-      (*if_master.if_new_hook) (ifp);
   }
 
+  ifp->connected = list_new ();
+  ifp->connected->del = (void (*) (void *)) connected_free;
+    
+  if (if_master.if_new_hook)
+    (*if_master.if_new_hook) (ifp);
+
   return ifp;
 }
 
@@ -149,7 +150,11 @@ if_delete_retain (struct interface *ifp)
     (*if_master.if_delete_hook) (ifp);
 
   /* Free connected address list */
-  list_delete (ifp->connected);
+  if (ifp->connected)
+    {
+      list_delete (ifp->connected);
+      ifp->connected = NULL;
+    }
 }
 
 /* Delete and free interface structure. */
diff --git a/zebra/interface.c b/zebra/interface.c
index 12b2c500..75a3e1cb 100644
--- a/zebra/interface.c
+++ b/zebra/interface.c
@@ -102,6 +102,7 @@ if_zebra_delete_hook (struct interface *ifp)
 	route_table_finish (zebra_if->ipv4_subnets);
 
       XFREE (MTYPE_TMP, zebra_if);
+      ifp->info = NULL;
     }
 
   return 0;
@@ -496,16 +497,18 @@ if_rename (struct interface *ifp, const char *name)
 	oifp = if_lookup_by_name(name);
 	if (oifp)
 	  {
-	    if (oifp->ifindex != IFINDEX_INTERNAL)
-	      {
-		zlog_warn ("interface rname %s to %s overlaps earlier interface",
-			   ifp->name, name);
-		if_delete_update (oifp);
-	      }
-	    if (IS_ZEBRA_DEBUG_KERNEL)
-	      zlog_debug ("interface %s superseded by rename of %s",
-			  oifp->name, ifp->name);
-	    if_delete (oifp);
+	      if (oifp->ifindex != IFINDEX_INTERNAL)
+		{
+		  zlog_err ("interface %s rename to %s overlaps with index %d",
+			    ifp->name, name, oifp->ifindex);
+		  if_delete_update (oifp);
+		}
+	      else if (IS_ZEBRA_DEBUG_KERNEL)
+		zlog_debug ("interface %s index %d superseded by rename of %s",
+			    oifp->name, oifp->ifindex, ifp->name);
+
+	      listnode_delete (iflist, oifp);
+	      XFREE (MTYPE_IF, oifp);
 	  }
 
 	strncpy(ifp->name, name, INTERFACE_NAMSIZ);