staging: panel: fix stackdump

sudipm-mukherjee · gregkh · commit 7d98c63edc45 · 2015-05-24T13:35:25.000-07:00
if we load the module, unload and then again try to load the module, we will get a stackdump. In the module_exit function we are unregistering the device and releasing the parport. So when we reach the detach function parport is already null and the unregister_reboot_notifier() is never called. When we again try to load the module it again tries register_reboot_notifier() and gives us a stackdump as its earlier registration is still not removed. It was caused by the commit bb046fe ('staging: panel: register reboot') Fix this by moving all the unregistering and releasing in the detach function, which should be the ideal case as the detach will be called if we try to unregister the driver or if the parport is removed. Fixes: bb046fe ('staging: panel: register reboot') Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/staging/panel/panel.c b/drivers/staging/panel/panel.c
@@ -2250,8 +2250,28 @@ static void panel_detach(struct parport *port)
 		       __func__, port->number, parport);
 		return;
 	}
+	if (scan_timer.function != NULL)
+		del_timer_sync(&scan_timer);
 
-	unregister_reboot_notifier(&panel_notifier);
+	if (pprt != NULL) {
+		if (keypad.enabled) {
+			misc_deregister(&keypad_dev);
+			keypad_initialized = 0;
+		}
+
+		if (lcd.enabled) {
+			panel_lcd_print("\x0cLCD driver " PANEL_VERSION
+					"\nunloaded.\x1b[Lc\x1b[Lb\x1b[L-");
+			misc_deregister(&lcd_dev);
+			lcd.initialized = false;
+		}
+
+		/* TODO: free all input signals */
+		parport_release(pprt);
+		parport_unregister_device(pprt);
+		pprt = NULL;
+		unregister_reboot_notifier(&panel_notifier);
+	}
 }
 
 static struct parport_driver panel_driver = {
@@ -2384,28 +2404,6 @@ static int __init panel_init_module(void)
 
 static void __exit panel_cleanup_module(void)
 {
-
-	if (scan_timer.function != NULL)
-		del_timer_sync(&scan_timer);
-
-	if (pprt != NULL) {
-		if (keypad.enabled) {
-			misc_deregister(&keypad_dev);
-			keypad_initialized = 0;
-		}
-
-		if (lcd.enabled) {
-			panel_lcd_print("\x0cLCD driver " PANEL_VERSION
-					"\nunloaded.\x1b[Lc\x1b[Lb\x1b[L-");
-			misc_deregister(&lcd_dev);
-			lcd.initialized = false;
-		}
-
-		/* TODO: free all input signals */
-		parport_release(pprt);
-		parport_unregister_device(pprt);
-		pprt = NULL;
-	}
 	parport_unregister_driver(&panel_driver);
 }
 
