Re: [PATCH] Input: serio - clear serio event queue after sysfs driver rebind

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Wed, Feb 02, 2011 at 02:41:38PM -0800, Duncan Laurie wrote:
> On Tue, Feb 1, 2011 at 1:21 AM, Dmitry Torokhov
> <dmitry.torokhov@gmail.com> wrote:
> > On Tue, Dec 07, 2010 at 09:12:11PM -0800, Dmitry Torokhov wrote:
> >> On Mon, Nov 29, 2010 at 01:37:35PM -0800, Duncan Laurie wrote:
> >> > On Sat, Nov 27, 2010 at 12:41 AM, Dmitry Torokhov
> >> > <dmitry.torokhov@gmail.com> wrote:
> >> > > Hi Duncan,
> >> > >
> >> > > On Mon, Nov 22, 2010 at 03:09:50PM -0800, Duncan Laurie wrote:
> >> > >> When rebinding a serio driver via sysfs drvctl interface it is possible for
> >> > >> an interrupt to trigger after the disconnect of the existing driver and
> >> > >> before the binding of the new driver.  This will cause the serio interrupt
> >> > >> handler to queue a rescan event which will disconnect the new driver
> >> > >> immediately after it is attached.
> >> > >>
> >> > >> This change clears the serio event queue after processing the drvctl
> >> > >> request but before releasing the serio mutex, which will clear any queued
> >> > >> rescans before they can get processed.
> >> > >>
> >> > >> Reproduction involves issuing a rebind of device port from psmouse driver
> >> > >> to serio_raw driver while generating input to trigger interrupts.  Then
> >> > >> checking to see if the corresponding i8042/serio4/driver is correctly
> >> > >> attached to the serio_raw driver instead of psmouse.
> >> > >>
> >> > >> Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
> >> > >> ---
> >> > >>  drivers/input/serio/serio.c |    1 +
> >> > >>  1 files changed, 1 insertions(+), 0 deletions(-)
> >> > >>
> >> > >> diff --git a/drivers/input/serio/serio.c b/drivers/input/serio/serio.c
> >> > >> index 405bf21..a66307e 100644
> >> > >> --- a/drivers/input/serio/serio.c
> >> > >> +++ b/drivers/input/serio/serio.c
> >> > >> @@ -454,6 +454,7 @@ static ssize_t serio_rebind_driver(struct device *dev, struct device_attribute *
> >> > >>               serio_disconnect_port(serio);
> >> > >>               error = serio_bind_driver(serio, to_serio_driver(drv));
> >> > >>               put_driver(drv);
> >> > >> +             serio_remove_pending_events(serio);
> >> > >
> >> > > Hmm, makes sense, although should we limit events being removed to
> >> > > rescan events only?
> >> > >
> >> >
> >> >
> >> > That seems reasonable.  It would mean adding a new function or a
> >> > parameter to the existing serio_remove_pending_events function, do you
> >> > have a preference?
> >> >
> >>
> >> I wonder if a boolean parameter (rescan_only) would not be the best
> >> option.
> >>
> >
> > Hi Duncan,
> >
> > I eneded up with the following patch, could you please try and see if
> > it still works for you?
> >
> 
> 
> Hi Dmitry,
> 
> I tested the patch on a CR-48 device (which is where I was seeing the
> problem because we switch to serio_raw at boot for the trackpad) and
> it does fix the problem.
> 
> Thanks for sending this, it had slipped off my todo list.
> 

Great, thank you for testing.

-- 
Dmitry
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