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

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Message-ID: <AANLkTik1TE9zgKaiLQZ=1uFgMyZt43xp8VJBWfxdVyMY@mail.gmail.com>
Date:	Mon, 29 Nov 2010 13:37:35 -0800
From:	Duncan Laurie <dlaurie@...omium.org>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input: serio - clear serio event queue after sysfs driver rebind

On Sat, Nov 27, 2010 at 12:41 AM, Dmitry Torokhov
<dmitry.torokhov@...il.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@...omium.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?

Thanks,
-duncan
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