USB: g_mass_storage: thread_exits callback added

thread_exits callback has been added to fsg_common structure.
This callback is called when MSF's thread exits (is terminated
by a signal or function is unregistered).  It's then gadget's
responsibility to unregister the gadget.
Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/f_mass_storage.c

@@ -367,6 +367,11 @@ struct fsg_common {
 	struct completion	thread_notifier;
 	struct task_struct	*thread_task;
 
+	/* Callback function to call when thread exits. */
+	void			(*thread_exits)(struct fsg_common *common);
+	/* Gadget's private data. */
+	void			*private_data;
+
 	/* Vendor (8 chars), product (16 chars), release (4
 	 * hexadecimal digits) and NUL byte */
 	char inquiry_string[8 + 16 + 4 + 1];
@@ -387,6 +392,11 @@ struct fsg_config {
 	const char		*lun_name_format;
 	const char		*thread_name;
 
+	/* Callback function to call when thread exits. */
+	void			(*thread_exits)(struct fsg_common *common);
+	/* Gadget's private data. */
+	void			*private_data;
+
 	const char *vendor_name;		/*  8 characters or less */
 	const char *product_name;		/* 16 characters or less */
 	u16 release;
@@ -2605,11 +2615,8 @@ static int fsg_main_thread(void *common_)
 	common->thread_task = NULL;
 	spin_unlock_irq(&common->lock);
 
-	/* XXX */
-	/* If we are exiting because of a signal, unregister the
-	 * gadget driver. */
-	/* if (test_and_clear_bit(REGISTERED, &fsg->atomic_bitflags)) */
-	/* 	usb_gadget_unregister_driver(&fsg_driver); */
+	if (common->thread_exits)
+		common->thread_exits(common);
 
 	/* Let the unbind and cleanup routines know the thread has exited */
 	complete_and_exit(&common->thread_notifier, 0);
@@ -2672,6 +2679,8 @@ static struct fsg_common *fsg_common_init(struct fsg_common *common,
 		common->free_storage_on_release = 0;
 	}
 
+	common->private_data = cfg->private_data;
+
 	common->gadget = gadget;
 	common->ep0 = gadget->ep0;
 	common->ep0req = cdev->req;
@@ -2791,6 +2800,7 @@ static struct fsg_common *fsg_common_init(struct fsg_common *common,
 
 
 	/* Tell the thread to start working */
+	common->thread_exits = cfg->thread_exits;
 	common->thread_task =
 		kthread_create(fsg_main_thread, common,
 			       OR(cfg->thread_name, "file-storage"));
@@ -3057,6 +3067,9 @@ fsg_config_from_params(struct fsg_config *cfg,
 	cfg->product_name = 0;
 	cfg->release = 0xffff;
 
+	cfg->thread_exits = 0;
+	cfg->private_data = 0;
+
 	/* Finalise */
 	cfg->can_stall = params->stall;
 }

drivers/usb/gadget/mass_storage.c

@@ -132,9 +132,13 @@ static struct fsg_module_parameters mod_data = {
 };
 FSG_MODULE_PARAMETERS(/* no prefix */, mod_data);
 
+static unsigned long msg_registered = 0;
+static void msg_cleanup(void);
+
 static int __init msg_do_config(struct usb_configuration *c)
 {
 	struct fsg_common *common;
+	struct fsg_config config;
 	int ret;
 
 	if (gadget_is_otg(c->cdev->gadget)) {
@@ -142,7 +146,9 @@ static int __init msg_do_config(struct usb_configuration *c)
 		c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
 	}
 
-	common = fsg_common_from_params(0, c->cdev, &mod_data);
+	fsg_config_from_params(&config, &mod_data);
+	config.thread_exits = (void(*)(struct fsg_common*))&msg_cleanup;
+	common = fsg_common_init(0, c->cdev, &config);
 	if (IS_ERR(common))
 		return PTR_ERR(common);
 
@@ -201,11 +207,7 @@ static int __init msg_bind(struct usb_composite_dev *cdev)
 		return status;
 
 	dev_info(&gadget->dev, DRIVER_DESC ", version: " DRIVER_VERSION "\n");
-	return 0;
-}
-
-static int __exit msg_unbind(struct usb_composite_dev *cdev)
-{
+	set_bit(0, &msg_registered);
 	return 0;
 }
 
@@ -218,7 +220,6 @@ static struct usb_composite_driver msg_driver = {
 	.dev		= &msg_device_desc,
 	.strings	= dev_strings,
 	.bind		= msg_bind,
-	.unbind		= __exit_p(msg_unbind),
 };
 
 MODULE_DESCRIPTION(DRIVER_DESC);
@@ -231,8 +232,9 @@ static int __init msg_init(void)
 }
 module_init(msg_init);
 
-static void __exit msg_cleanup(void)
+static void msg_cleanup(void)
 {
-	usb_composite_unregister(&msg_driver);
+	if (test_and_clear_bit(0, &msg_registered))
+		usb_composite_unregister(&msg_driver);
 }
 module_exit(msg_cleanup);