USB: legousbtower: use usb_control_msg_recv()

The usb_control_msg_recv() function can handle data on the stack, as
well as properly detecting short reads, so move to use that function
instead of the older usb_control_msg() call.  This ends up removing a
lot of extra lines in the driver.

v2: change API of usb_control_msg_send()

Cc: Juergen Stuber <starblue@users.sourceforge.net>
Link: https://lore.kernel.org/r/20200914153756.3412156-6-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200923134348.23862-12-oneukum@suse.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/misc/legousbtower.c

@@ -308,15 +308,9 @@ static int tower_open(struct inode *inode, struct file *file)
 	int subminor;
 	int retval = 0;
 	struct usb_interface *interface;
-	struct tower_reset_reply *reset_reply;
+	struct tower_reset_reply reset_reply;
 	int result;
 
-	reset_reply = kmalloc(sizeof(*reset_reply), GFP_KERNEL);
-	if (!reset_reply) {
-		retval = -ENOMEM;
-		goto exit;
-	}
-
 	nonseekable_open(inode, file);
 	subminor = iminor(inode);
 
@@ -347,15 +341,12 @@ static int tower_open(struct inode *inode, struct file *file)
 	}
 
 	/* reset the tower */
-	result = usb_control_msg(dev->udev,
-				 usb_rcvctrlpipe(dev->udev, 0),
+	result = usb_control_msg_recv(dev->udev, 0,
 				      LEGO_USB_TOWER_REQUEST_RESET,
 				      USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
-				 0,
-				 0,
-				 reset_reply,
-				 sizeof(*reset_reply),
-				 1000);
+				      0, 0,
+				      &reset_reply, sizeof(reset_reply), 1000,
+				      GFP_KERNEL);
 	if (result < 0) {
 		dev_err(&dev->udev->dev,
 			"LEGO USB Tower reset control request failed\n");
@@ -394,7 +385,6 @@ static int tower_open(struct inode *inode, struct file *file)
 	mutex_unlock(&dev->lock);
 
 exit:
-	kfree(reset_reply);
 	return retval;
 }
 
@@ -753,7 +743,7 @@ static int tower_probe(struct usb_interface *interface, const struct usb_device_
 	struct device *idev = &interface->dev;
 	struct usb_device *udev = interface_to_usbdev(interface);
 	struct lego_usb_tower *dev;
-	struct tower_get_version_reply *get_version_reply = NULL;
+	struct tower_get_version_reply get_version_reply;
 	int retval = -ENOMEM;
 	int result;
 
@@ -798,34 +788,25 @@ static int tower_probe(struct usb_interface *interface, const struct usb_device_
 	dev->interrupt_in_interval = interrupt_in_interval ? interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
 	dev->interrupt_out_interval = interrupt_out_interval ? interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
 
-	get_version_reply = kmalloc(sizeof(*get_version_reply), GFP_KERNEL);
-	if (!get_version_reply) {
-		retval = -ENOMEM;
-		goto error;
-	}
-
 	/* get the firmware version and log it */
-	result = usb_control_msg(udev,
-				 usb_rcvctrlpipe(udev, 0),
+	result = usb_control_msg_recv(udev, 0,
 				      LEGO_USB_TOWER_REQUEST_GET_VERSION,
 				      USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 				      0,
 				      0,
-				 get_version_reply,
-				 sizeof(*get_version_reply),
-				 1000);
-	if (result != sizeof(*get_version_reply)) {
-		if (result >= 0)
-			result = -EIO;
+				      &get_version_reply,
+				      sizeof(get_version_reply),
+				      1000, GFP_KERNEL);
+	if (!result) {
 		dev_err(idev, "get version request failed: %d\n", result);
 		retval = result;
 		goto error;
 	}
 	dev_info(&interface->dev,
 		 "LEGO USB Tower firmware version is %d.%d build %d\n",
-		 get_version_reply->major,
-		 get_version_reply->minor,
-		 le16_to_cpu(get_version_reply->build_no));
+		 get_version_reply.major,
+		 get_version_reply.minor,
+		 le16_to_cpu(get_version_reply.build_no));
 
 	/* we can register the device now, as it is ready */
 	usb_set_intfdata(interface, dev);
@@ -844,11 +825,9 @@ static int tower_probe(struct usb_interface *interface, const struct usb_device_
 		 USB_MAJOR, dev->minor);
 
 exit:
-	kfree(get_version_reply);
 	return retval;
 
 error:
-	kfree(get_version_reply);
 	tower_delete(dev);
 	return retval;
 }