Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit e8c65d14 authored by Alan Cox's avatar Alan Cox Committed by Greg Kroah-Hartman
Browse files

nozomi: Fix mutex handling 



The original author didn't realise the kernel lock was a drop while sleep
lock so did clever (and wrong) things to work around the non need to avoid
deadlocks. Remove the cleverness and the comment (as we don't hold the BKL
now anyway in those paths)

Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 266794eb

drivers/char/nozomi.c

+12 −22
Original line number Diff line number Diff line
@@ -1693,15 +1693,7 @@ static int ntty_write(struct tty_struct *tty, const unsigned char *buffer, 
	if (!dc || !port)

		return -ENODEV;



	if (unlikely(!mutex_trylock(&port->tty_sem))) {

		/*

		 * must test lock as tty layer wraps calls

		 * to this function with BKL

		 */

		dev_err(&dc->pdev->dev, "Would have deadlocked - "

			"return EAGAIN\n");

		return -EAGAIN;

	}

	mutex_lock(&port->tty_sem);



	if (unlikely(!port->port.count)) {

		DBG1(" ");
@@ -1741,25 +1733,23 @@ exit: 
 * This method is called by the upper tty layer.

 *   #according to sources N_TTY.c it expects a value >= 0 and

 *    does not check for negative values.

 *

 * If the port is unplugged report lots of room and let the bits

 * dribble away so we don't block anything.

 */

static int ntty_write_room(struct tty_struct *tty)

{

	struct port *port = tty->driver_data;

	int room = 0;

	int room = 4096;

	const struct nozomi *dc = get_dc_by_tty(tty);



	if (!dc || !port)

		return 0;

	if (!mutex_trylock(&port->tty_sem))

		return 0;



	if (!port->port.count)

		goto exit;



	room = port->fifo_ul.size - kfifo_len(&port->fifo_ul);



exit:

	if (dc) {

		mutex_lock(&port->tty_sem);

		if (port->port.count)

			room = port->fifo_ul.size -

					kfifo_len(&port->fifo_ul);

		mutex_unlock(&port->tty_sem);

	}

	return room;

}