[PATCH 098/150] USB: serial: add modem-status-change wait queue

[Johan Hovold]

On Tue, Mar 26, 2013 at 03:19:57PM +0000, Luis Henriques wrote:
> 3.5.7.9 -stable review patch.  If anyone has any objections, please let me know.

This patch is incorrect as the wait-queue initialisation is missing. A
fix has been posted to linux-usb:

	http://marc.info/?l=linux-usb&m=136428758202815&w=2

and should show up in 3.9-rc5. This patch and the following
use-after-free patches should not be applied without that fix.

Johan

> ------------------
> 
> From: Johan Hovold <jhovold at gmail.com>
> 
> commit e5b33dc9d16053c2ae4c2c669cf008829530364b upstream.
> 
> Add modem-status-change wait queue to struct usb_serial_port that
> subdrivers can use to implement TIOCMIWAIT.
> 
> Currently subdrivers use a private wait queue which may have been
> released when waking up after device disconnected.
> 
> Note that we're adding a new wait queue rather than reusing the tty-port
> one as we do not want to get woken up at hangup (yet).
> 
> Signed-off-by: Johan Hovold <jhovold at gmail.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
> ---
>  include/linux/usb/serial.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
> index 86c0b45..0b61f01 100644
> --- a/include/linux/usb/serial.h
> +++ b/include/linux/usb/serial.h
> @@ -66,6 +66,7 @@
>   *	port.
>   * @flags: usb serial port flags
>   * @write_wait: a wait_queue_head_t used by the port.
> + * @delta_msr_wait: modem-status-change wait queue
>   * @work: work queue entry for the line discipline waking up.
>   * @throttled: nonzero if the read urb is inactive to throttle the device
>   * @throttle_req: nonzero if the tty wants to throttle us
> @@ -112,6 +113,7 @@ struct usb_serial_port {
>  
>  	unsigned long		flags;
>  	wait_queue_head_t	write_wait;
> +	wait_queue_head_t	delta_msr_wait;
>  	struct work_struct	work;
>  	char			throttled;
>  	char			throttle_req;