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

[Luis Henriques]

On Tue, Mar 26, 2013 at 04:31:18PM +0100, Johan Hovold wrote:
> 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.

Ups, I missed that.  Thanks Johan, I'll drop these patches for now and
will queued them again to 3.5 later.

Cheers,
--
Luis


> 
> 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;