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

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Message-ID: <joqpa647tq7mh3lyl27zjv3wr4xbixuuvq7ifti3isifz3gfxg@p3ibbvrsuxud>
Date: Wed, 17 Dec 2025 10:13:16 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Duoming Zhou <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 Wed, Dec 17, 2025 at 11:00:18AM +0800, Duoming Zhou 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.

Thanks.

-- 
Dmitry