USB: serial: keyspan_pda: use usb_control_msg_recv()

Use the wrapper function usb_control_msg_recv() that accepts stack
variables and remove dma buffers from callers of usb_control_msg().

Signed-off-by: Himadri Pandya <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[ johan: simplify write-room error handling further ]
Signed-off-by: Johan Hovold <[e-mail]>

drivers/usb/serial/keyspan_pda.c

···
 {
 	struct usb_serial_port *port = priv->port;
 	struct usb_serial *serial = port->serial;
-	u8 *room;
+	u8 room;
 	int rc;
 
-	room = kmalloc(1, GFP_KERNEL);
-	if (!room)
-		return -ENOMEM;
-
-	rc = usb_control_msg(serial->dev,
-			     usb_rcvctrlpipe(serial->dev, 0),
-			     6, /* write_room */
-			     USB_TYPE_VENDOR | USB_RECIP_INTERFACE
-			     | USB_DIR_IN,
-			     0, /* value: 0 means "remaining room" */
-			     0, /* index */
-			     room,
-			     1,
-			     2000);
-	if (rc != 1) {
-		if (rc >= 0)
-			rc = -EIO;
+	rc = usb_control_msg_recv(serial->dev,
+				  0,
+				  6, /* write_room */
+				  USB_TYPE_VENDOR | USB_RECIP_INTERFACE | USB_DIR_IN,
+				  0, /* value: 0 means "remaining room" */
+				  0, /* index */
+				  &room,
+				  1,
+				  2000,
+				  GFP_KERNEL);
+	if (rc) {
 		dev_dbg(&port->dev, "roomquery failed: %d\n", rc);
-		goto out_free;
+		return rc;
 	}
 
-	dev_dbg(&port->dev, "roomquery says %d\n", *room);
-	rc = *room;
-out_free:
-	kfree(room);
+	dev_dbg(&port->dev, "roomquery says %d\n", room);
 
-	return rc;
+	return room;
 }
 
 static void keyspan_pda_request_unthrottle(struct work_struct *work)
···
 				      unsigned char *value)
 {
 	int rc;
-	u8 *data;
+	u8 data;
 
-	data = kmalloc(1, GFP_KERNEL);
-	if (!data)
-		return -ENOMEM;
+	rc = usb_control_msg_recv(serial->dev, 0,
+				  3, /* get pins */
+				  USB_TYPE_VENDOR | USB_RECIP_INTERFACE | USB_DIR_IN,
+				  0,
+				  0,
+				  &data,
+				  1,
+				  2000,
+				  GFP_KERNEL);
+	if (rc == 0)
+		*value = data;
 
-	rc = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
-			     3, /* get pins */
-			     USB_TYPE_VENDOR|USB_RECIP_INTERFACE|USB_DIR_IN,
-			     0, 0, data, 1, 2000);
-	if (rc == 1)
-		*value = *data;
-	else if (rc >= 0)
-		rc = -EIO;
-
-	kfree(data);
 	return rc;
 }