Convergence Improvements

addressing convergence times when interface is shut.
1) prioritise the registered callback handlers. Add FIB convergence handler as high priority
2) hook the FIB convergence call-back into HW link down.
3) don't schedule a walk of a FIB node if it has no children
4) Checks at fib_path_t to prevent unnecessary walks, that it prevent the same information propagting the graph multiple times.

Change-Id: I406966b50f31d77c221821b8649776d66655194c
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 87 insertions, 12 deletions

diff --git a/vnet/vnet/adj/adj_nbr.c b/vnet/vnet/adj/adj_nbr.c
index 4245990585e..1a78ecbc49f 100644
--- a/vnet/vnet/adj/adj_nbr.c
+++ b/vnet/vnet/adj/adj_nbr.c
@@ -604,30 +604,47 @@ adj_nbr_walk_nh (u32 sw_if_index,
 }
 
 /**
+ * Flags associated with the interface state walks
+ */
+typedef enum adj_nbr_interface_flags_t_
+{
+    ADJ_NBR_INTERFACE_UP = (1 << 0),
+} adj_nbr_interface_flags_t;
+
+/**
  * Context for the state change walk of the DB
  */
 typedef struct adj_nbr_interface_state_change_ctx_t_
 {
     /**
-     * Flags passed from the vnet notifiy function
+     * Flags on the interface
      */
-    int flags;
+    adj_nbr_interface_flags_t flags;
 } adj_nbr_interface_state_change_ctx_t;
 
 static adj_walk_rc_t
 adj_nbr_interface_state_change_one (adj_index_t ai,
-				    void *arg)
+                                    void *arg)
 {
     /*
      * Back walk the graph to inform the forwarding entries
-     * that this interface state has changed.
+     * that this interface state has changed. Do this synchronously
+     * since this is the walk that provides convergence
      */
     adj_nbr_interface_state_change_ctx_t *ctx = arg;
 
     fib_node_back_walk_ctx_t bw_ctx = {
-	.fnbw_reason = (ctx->flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP ?
-			FIB_NODE_BW_REASON_FLAG_INTERFACE_UP :
-			FIB_NODE_BW_REASON_FLAG_INTERFACE_DOWN),
+	.fnbw_reason = ((ctx->flags & ADJ_NBR_INTERFACE_UP) ?
+                        FIB_NODE_BW_REASON_FLAG_INTERFACE_UP :
+                        FIB_NODE_BW_REASON_FLAG_INTERFACE_DOWN),
+        /*
+         * the force sync applies only as far as the first fib_entry.
+         * And it's the fib_entry's we need to converge away from
+         * the adjacencies on the now down link
+         */
+        .fnbw_flags = (!(ctx->flags & ADJ_NBR_INTERFACE_UP) ?
+                       FIB_NODE_BW_FLAG_FORCE_SYNC :
+                       0),
     };
 
     fib_walk_sync(FIB_NODE_TYPE_ADJ, ai, &bw_ctx);
@@ -635,10 +652,13 @@ adj_nbr_interface_state_change_one (adj_index_t ai,
     return (ADJ_WALK_RC_CONTINUE);
 }
 
+/**
+ * @brief Registered function for SW interface state changes
+ */
 static clib_error_t *
-adj_nbr_interface_state_change (vnet_main_t * vnm,
-				u32 sw_if_index,
-				u32 flags)
+adj_nbr_sw_interface_state_change (vnet_main_t * vnm,
+                                   u32 sw_if_index,
+                                   u32 flags)
 {
     fib_protocol_t proto;
 
@@ -648,7 +668,9 @@ adj_nbr_interface_state_change (vnet_main_t * vnm,
     for (proto = FIB_PROTOCOL_IP4; proto <= FIB_PROTOCOL_IP6; proto++)
     {
 	adj_nbr_interface_state_change_ctx_t ctx = {
-	    .flags = flags,
+	    .flags = ((flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP) ?
+                      ADJ_NBR_INTERFACE_UP :
+                      0),
 	};
 
 	adj_nbr_walk(sw_if_index, proto,
@@ -659,7 +681,60 @@ adj_nbr_interface_state_change (vnet_main_t * vnm,
     return (NULL);
 }
 
-VNET_SW_INTERFACE_ADMIN_UP_DOWN_FUNCTION(adj_nbr_interface_state_change);
+VNET_SW_INTERFACE_ADMIN_UP_DOWN_FUNCTION_PRIO(
+    adj_nbr_sw_interface_state_change,
+    VNET_ITF_FUNC_PRIORITY_HIGH);
+
+/**
+ * @brief Invoked on each SW interface of a HW interface when the
+ * HW interface state changes
+ */
+static void
+adj_nbr_hw_sw_interface_state_change (vnet_main_t * vnm,
+                                      u32 sw_if_index,
+                                      void *arg)
+{
+    adj_nbr_interface_state_change_ctx_t *ctx = arg;
+    fib_protocol_t proto;
+
+    /*
+     * walk each adj on the interface and trigger a walk from that adj
+     */
+    for (proto = FIB_PROTOCOL_IP4; proto <= FIB_PROTOCOL_IP6; proto++)
+    {
+	adj_nbr_walk(sw_if_index, proto,
+		     adj_nbr_interface_state_change_one,
+		     ctx);
+    }
+}
+
+/**
+ * @brief Registered callback for HW interface state changes
+ */
+static clib_error_t *
+adj_nbr_hw_interface_state_change (vnet_main_t * vnm,
+                                   u32 hw_if_index,
+                                   u32 flags)
+{
+    /*
+     * walk SW interface on the HW
+     */
+    adj_nbr_interface_state_change_ctx_t ctx = {
+        .flags = ((flags & VNET_HW_INTERFACE_FLAG_LINK_UP) ?
+                  ADJ_NBR_INTERFACE_UP :
+                  0),
+    };
+
+    vnet_hw_interface_walk_sw(vnm, hw_if_index,
+                              adj_nbr_hw_sw_interface_state_change,
+                              &ctx);
+
+    return (NULL);
+}
+
+VNET_HW_INTERFACE_LINK_UP_DOWN_FUNCTION_PRIO(
+    adj_nbr_hw_interface_state_change,
+    VNET_ITF_FUNC_PRIORITY_HIGH);
 
 static adj_walk_rc_t
 adj_nbr_interface_delete_one (adj_index_t ai,