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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>
This commit is contained in:
Johan Hovold 2010-03-17 23:06:02 +01:00 committed by Greg Kroah-Hartman
parent 1a1405e225
commit 50a5f70cee
1 changed files with 5 additions and 12 deletions
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17
drivers/usb/serial/generic.c
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@ -259,21 +259,14 @@ 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;
}
spin_unlock_irqrestore(&port->lock, flags);
if (!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);
data = port->write_urb->transfer_buffer;
count = kfifo_out_locked(&port->write_fifo, data, port->bulk_out_size, &port->lock);