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Commit 8f9818af authored by Olivier Sobrie's avatar Olivier Sobrie Committed by David S. Miller
Browse files

hso: fix deadlock when receiving bursts of data 



When the module sends bursts of data, sometimes a deadlock happens in
the hso driver when the tty buffer doesn't get the chance to be flushed
quickly enough.

Remove the endless while loop in function put_rxbuf_data() which is
called by the urb completion handler.
If there isn't enough room in the tty buffer, discards all the data
received in the URB.

Cc: David Miller <davem@davemloft.net>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Dan Williams <dcbw@redhat.com>
Cc: Jan Dumon <j.dumon@option.com>
Signed-off-by: default avatarOlivier Sobrie <olivier@sobrie.be>
Acked-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5c763edf

drivers/net/usb/hso.c

+17 −21
Original line number Diff line number Diff line
@@ -258,7 +258,6 @@ struct hso_serial { 
	 * so as not to drop characters on the floor.

	 */

	int  curr_rx_urb_idx;

	u16  curr_rx_urb_offset;

	u8   rx_urb_filled[MAX_RX_URBS];

	struct tasklet_struct unthrottle_tasklet;

};
@@ -2001,8 +2000,7 @@ static void ctrl_callback(struct urb *urb) 
static int put_rxbuf_data(struct urb *urb, struct hso_serial *serial)

{

	struct tty_struct *tty;

	int write_length_remaining = 0;

	int curr_write_len;

	int count;



	/* Sanity check */

	if (urb == NULL || serial == NULL) {
@@ -2012,29 +2010,28 @@ static int put_rxbuf_data(struct urb *urb, struct hso_serial *serial) 


	tty = tty_port_tty_get(&serial->port);



	/* Push data to tty */

	write_length_remaining = urb->actual_length -

		serial->curr_rx_urb_offset;

	D1("data to push to tty");

	while (write_length_remaining) {

	if (tty && test_bit(TTY_THROTTLED, &tty->flags)) {

		tty_kref_put(tty);

		return -1;

	}

		curr_write_len = tty_insert_flip_string(&serial->port,

			urb->transfer_buffer + serial->curr_rx_urb_offset,

			write_length_remaining);

		serial->curr_rx_urb_offset += curr_write_len;

		write_length_remaining -= curr_write_len;



	/* Push data to tty */

	D1("data to push to tty");

	count = tty_buffer_request_room(&serial->port, urb->actual_length);

	if (count >= urb->actual_length) {

		tty_insert_flip_string(&serial->port, urb->transfer_buffer,

				       urb->actual_length);

		tty_flip_buffer_push(&serial->port);

	} else {

		dev_warn(&serial->parent->usb->dev,

			 "dropping data, %d bytes lost\n", urb->actual_length);

	}



	tty_kref_put(tty);



	if (write_length_remaining == 0) {

		serial->curr_rx_urb_offset = 0;

	serial->rx_urb_filled[hso_urb_to_index(serial, urb)] = 0;

	}

	return write_length_remaining;



	return 0;

}
@@ -2205,7 +2202,6 @@ static int hso_stop_serial_device(struct hso_device *hso_dev) 
		}

	}

	serial->curr_rx_urb_idx = 0;

	serial->curr_rx_urb_offset = 0;



	if (serial->tx_urb)

		usb_kill_urb(serial->tx_urb);