lcd/ixgbe: Add a mechanism for graceful exit of LCD

A module parameter is added to the KLCD module, which is exposed by the kernel
in sysfs. The dispatch loop monitors for a change in this variable and sends a
message to LCD to exit, thereby paving way for LCD to gracefully exit.
Signed-off-by: Vikram Narayanan <vikram186@gmail.com>

lcd-domains/test_mods/ixgbe/ixgbe_lcd/glue/ixgbe_caller_dispatch.c

@@ -5,6 +5,8 @@
 
 #define trace(x) LIBLCD_MSG("net got " #x " msg")
 
+extern void ixgbe_exit_module(void);
+
 int dispatch_async_loop(struct thc_channel *_channel,
 		struct fipc_message *message,
 		struct glue_cspace *cspace,
@@ -27,6 +29,14 @@ int dispatch_async_loop(struct thc_channel *_channel,
 		cspace,
 		sync_ep);
 
+		case TRIGGER_EXIT:
+			trace(TRIGGER_EXIT);
+			ixgbe_exit_module();
+			/* XXX: return failure to exit the dispatch
+			 * loop. After exit, there is no reason to
+			 * be spinning on the loop
+			 */
+			return -1;
 		default:
 			LIBLCD_ERR("unexpected function label: %d",
 					fn_type);

lcd-domains/test_mods/ixgbe/ixgbe_lcd/main.c

@@ -86,18 +86,6 @@ static void main_and_loop(void)
 		LIBLCD_MSG("IXGBE EXITED DISPATCH LOOP");
 		);
 
-	/*
-	 * We don't expect any requests coming back to us, so it's safe
-	 * to just run this without a loop (it's effectively polling since
-	 * only one awe will run in this do-finish).
-	 */
-	DO_FINISH(
-		ASYNC(
-			ixgbe_exit_module();
-			LIBLCD_MSG("SUCCESSFULLY UNREGISTERED IXGBE driver!");
-			);
-		);
-
 	LIBLCD_MSG("EXITED IXGBE DO_FINISH");
 
 	return;

lcd-domains/test_mods/ixgbe/net_klcd/glue/ixgbe_callee.c

@@ -1903,3 +1903,34 @@ int pci_wake_from_d3_callee(struct fipc_message *_request,
 			_response);
 	return ret;
 }
+
+int trigger_exit_to_lcd(struct thc_channel *_channel)
+{
+	struct fipc_message *_request;
+	int ret;
+	unsigned int request_cookie;
+
+	dump_stack();
+	ret = async_msg_blocking_send_start(_channel,
+		&_request);
+	if (ret) {
+		LIBLCD_ERR("failed to get a send slot");
+		goto fail_async;
+	}
+	async_msg_set_fn_type(_request,
+			TRIGGER_EXIT);
+
+	/* No need to wait for a response here */
+	ret = thc_ipc_send_request(_channel,
+			_request,
+			&request_cookie);
+
+	if (ret) {
+		LIBLCD_ERR("thc_ipc send");
+		goto fail_ipc;
+	}
+
+fail_async:
+fail_ipc:
+	return ret;
+}
\ No newline at end of file

lcd-domains/test_mods/ixgbe/net_klcd/main.c

@@ -28,6 +28,9 @@ extern void destroy_async_net_ring_channel(struct thc_channel *chnl);
 extern struct glue_cspace *c_cspace;
 struct pci_driver_container *pci_container;
 
+static bool unload_lcd =0;
+module_param_named(unload, unload_lcd, bool, S_IWUSR);
+
 struct net_info *
 add_net(struct thc_channel *chnl, struct glue_cspace *cspace,
 	cptr_t sync_endpoint)
@@ -56,6 +59,15 @@ void remove_net(struct net_info *net)
 }
 
 
+static int __get_net(struct net_info **net_out)
+{
+	struct net_info *first;
+	first = list_first_entry_or_null(&net_infos, struct net_info, list);
+	if (first)
+		*net_out = first;
+	return first ? 1 : 0;
+}
+
 
 static int async_loop(struct net_info **net_out, struct fipc_message **msg_out)
 {
@@ -189,6 +201,8 @@ fail1:
 }
 #define REGISTER_FREQ	50
 
+extern int trigger_exit_to_lcd(struct thc_channel *_channel);
+
 static void loop(cptr_t register_chnl)
 {
 	unsigned long tics = jiffies + REGISTER_FREQ;
@@ -200,7 +214,6 @@ static void loop(cptr_t register_chnl)
 	DO_FINISH(
 
 		while (!stop) {
-			//LIBLCD_MSG(" tics %lu\n", tics);
 			if (jiffies >= tics) {
 				/*
 				 * Listen for a register call
@@ -213,16 +226,18 @@ static void loop(cptr_t register_chnl)
 				tics = jiffies + REGISTER_FREQ;
 				continue;
 			}
-			/*
-			if (ixgbe_ready) {
-				ixgbe_ready = 0;
-				ASYNC(
-					stop = do_ixgbe_test();
-					);
-			}
-			 */
 			if (stop)
 				break;
+
+			/*
+			 * will be updated by a write into sysfs
+			 * from userspace.
+			 */
+			if (unload_lcd) {
+				unload_lcd = 0;
+				if (__get_net(&net))
+					trigger_exit_to_lcd(net->chnl);
+			}
 			ret = async_loop(&net, &msg);
 			if (!ret) {
 				ASYNC(
@@ -263,10 +278,7 @@ static void loop(cptr_t register_chnl)
 
 		);
 
-	if (pci_container) {
-		pci_unregister_driver(&pci_container->pci_driver);
-	}
-	LIBLCD_MSG("EXITED IXGBE DO_FINISH");
+	LIBLCD_MSG("EXITED net_klcd DO_FINISH");
 }
 
 /* INIT / EXIT ---------------------------------------- */