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

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Message-ID: <20101127084153.GC28745@core.coreip.homeip.net>
Date:	Sat, 27 Nov 2010 00:41:53 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Duncan Laurie <dlaurie@...omium.org>
Cc:	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input: serio - clear serio event queue after sysfs
 driver rebind

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?

-- 
Dmitry
--
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