Re: [PATCH 15/62] Input: synaptics-rmi4 - fix a locking bug in an error path

[Dmitry Torokhov]

Hi Bart,

On Mon, Feb 23, 2026 at 01:50:30PM -0800, Bart Van Assche wrote:
> Lock f54->data_mutex before the first 'goto error' statement since
> jumping to the 'error' label causes that mutex to be unlocked.
> 
> This bug has been detected by the Clang thread-safety checker.
> 
> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> Cc: Nick Dyer <nick@xxxxxxxxxxxxx>
> Cc: linux-input@xxxxxxxxxxxxxxx
> Fixes: 3a762dbd5347 ("[media] Input: synaptics-rmi4 - add support for F54 diagnostics")
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
> ---
>  drivers/input/rmi4/rmi_f54.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/rmi4/rmi_f54.c b/drivers/input/rmi4/rmi_f54.c
> index ac4041a69fcd..fd57ebb1cb50 100644
> --- a/drivers/input/rmi4/rmi_f54.c
> +++ b/drivers/input/rmi4/rmi_f54.c
> @@ -539,6 +539,9 @@ static void rmi_f54_work(struct work_struct *work)
>  	int i;
>  
>  	report_size = rmi_f54_get_report_size(f54);
> +
> +	mutex_lock(&f54->data_mutex);
> +

Thank you for the patch. Do you mind if I move mutex_lock() above the
call to rmi_f54_get_report_size()? It does not extend critical section
by much, and I think logically makes more sense.

>  	if (report_size == 0) {
>  		dev_err(&fn->dev, "Bad report size, report type=%d\n",
>  				f54->report_type);
> @@ -546,8 +549,6 @@ static void rmi_f54_work(struct work_struct *work)
>  		goto error;     /* retry won't help */
>  	}
>  
> -	mutex_lock(&f54->data_mutex);
> -
>  	/*
>  	 * Need to check if command has completed.
>  	 * If not try again later.

Thanks.

-- 
Dmitry