linux-kernel - Re: [PATCH v2 RESEND 2/2] Input: psmouse - Replace flush_workqueue() with disable_delayed_work

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Message-ID: <ho33u6epmzsojiw5zvqksskpzo3f6z2lykvhgektf65stqj6sr@5hq6qd76ezxg>
Date: Wed, 17 Dec 2025 22:58:30 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: duoming@....edu.cn
Cc: linux-input@...r.kernel.org, linux-kernel@...r.kernel.org, 
	pali@...nel.org, kuba@...nel.org, alexander.deucher@....com, 
	akpm@...ux-foundation.org, johannes.berg@...el.com, pkshih@...ltek.com, 
	hverkuil+cisco@...nel.org, andriy.shevchenko@...ux.intel.com, tglx@...utronix.de, 
	mingo@...nel.org
Subject: Re: [PATCH v2 RESEND 2/2] Input: psmouse - Replace flush_workqueue()
 with disable_delayed_work_sync()

On Thu, Dec 18, 2025 at 01:49:03PM +0800, duoming@....edu.cn wrote:
> On Wed, 17 Dec 2025 10:13:16 -0800 Dmitry Torokhov wrote:
> > > The original code uses flush_workqueue() in psmouse_disconnect() to
> > > ensure the completion of both resync_work and dev3_register_work.
> > > Given that alps_disconnect() already uses disable_delayed_work_sync()
> > > to cancel dev3_register_work, replacing flush_workqueue() with
> > > disable_delayed_work_sync(&psmouse->resync_work) is more robust
> > > and efficient.
> > > 
> > > Signed-off-by: Duoming Zhou <duoming@....edu.cn>
> > > ---
> > > Changes in v2:
> > >   - focus on the robustness and efficiency improvements of disable_delayed_work_sync(), not on the UAF aspect.
> > > 
> > >  drivers/input/mouse/psmouse-base.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
> > > index 77ea7da3b1c..eb41c553e80 100644
> > > --- a/drivers/input/mouse/psmouse-base.c
> > > +++ b/drivers/input/mouse/psmouse-base.c
> > > @@ -1484,7 +1484,7 @@ static void psmouse_disconnect(struct serio *serio)
> > >  
> > >  	/* make sure we don't have a resync in progress */
> > >  	mutex_unlock(&psmouse_mutex);
> > > -	flush_workqueue(kpsmoused_wq);
> > > +	disable_delayed_work_sync(&psmouse->resync_work);
> > 
> > Before we replace flush_workqueue() with disable_delayed_work_sync() we
> > need to also add disable_delayed_work_sync() to
> > drivers/input/mouse/hgpk.c that also queues work to psmouse workqueue
> > and relies on flushing it when disconnecting.
> 
> The delayed work item recalib_wq could never be scheduled due to the 
> touchpad driver only supports mouse mode and the hgpk_init() function
> remains disabled.

What do you mean? If you enable OLPC support the option to enable hgpk
protocol driver should become available, right?

Thanks.

-- 
Dmitry