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

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Message-ID: <2e74b4a1.464cb.19b30013387.Coremail.duoming@zju.edu.cn>
Date: Thu, 18 Dec 2025 13:49:03 +0800 (GMT+08:00)
From: duoming@....edu.cn
To: "Dmitry Torokhov" <dmitry.torokhov@...il.com>
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 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.

Best regards,
Duoming Zhou