USB: serial: clean up generic write start busy test

Submit write urb if it is not already in use and we have buffered data.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 11 deletions

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 63b43308e160..9756b5c22d94 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -259,22 +259,15 @@ static int usb_serial_generic_write_start(struct usb_serial_port *port)
         int result;
         int count;
         unsigned long flags;
-        bool start_io;
 
-        /* Atomically determine whether we can and need to start a USB
-         * operation. */
         spin_lock_irqsave(&port->lock, flags);
-        if (port->write_urb_busy)
-                start_io = false;
-        else {
-                start_io = (kfifo_len(&port->write_fifo) != 0);
-                port->write_urb_busy = start_io;
+        if (port->write_urb_busy || !kfifo_len(&port->write_fifo)) {
+                spin_unlock_irqrestore(&port->lock, flags);
+                return 0;
         }
+        port->write_urb_busy = 1;
         spin_unlock_irqrestore(&port->lock, flags);
 
-        if (!start_io)
-                return 0;
-
         data = port->write_urb->transfer_buffer;
         count = kfifo_out_locked(&port->write_fifo, data, port->bulk_out_size, &port->lock);
         usb_serial_debug_data(debug, &port->dev, __func__, count, data);