zebra: during shutdown processing, drop dplane results

Don't process dataplane results in zebra during shutdown (after
sigint has been seen). The dplane continues to run in order to
clean up, but zebra main just drops results.

Signed-off-by: Mark Stapp <mjs@voltanet.io>

zebra/main.c

@@ -142,6 +142,9 @@ static void sigint(void)
 
 	zlog_notice("Terminating on signal");
 
+	atomic_store_explicit(&zrouter.in_shutdown, true,
+			      memory_order_relaxed);
+
 	frr_early_fini();
 
 	zebra_dplane_pre_finish();

zebra/zebra_rib.c

@@ -3204,6 +3204,7 @@ static int rib_process_dplane_results(struct thread *thread)
 {
 	struct zebra_dplane_ctx *ctx;
 	struct dplane_ctx_q ctxlist;
+	bool shut_p = false;
 
 	/* Dequeue a list of completed updates with one lock/unlock cycle */
 
@@ -3223,6 +3224,21 @@ static int rib_process_dplane_results(struct thread *thread)
 		if (ctx == NULL)
 			break;
 
+		/* If zebra is shutting down, avoid processing results,
+		 * just drain the results queue.
+		 */
+		shut_p = atomic_load_explicit(&zrouter.in_shutdown,
+					      memory_order_relaxed);
+		if (shut_p) {
+			while (ctx) {
+				dplane_ctx_fini(&ctx);
+
+				ctx = dplane_ctx_dequeue(&ctxlist);
+			}
+
+			continue;
+		}
+
 		while (ctx) {
 			switch (dplane_ctx_get_op(ctx)) {
 			case DPLANE_OP_ROUTE_INSTALL:

zebra/zebra_router.h

@@ -74,6 +74,8 @@ struct zebra_mlag_info {
 };
 
 struct zebra_router {
+	atomic_bool in_shutdown;
+
 	/* Thread master */
 	struct thread_master *master;