linux-kernel - Re: [PATCH 05/15] serial: sc16is7xx: use guards for simple mutex locks

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Message-ID: <0a606585-a7fb-4457-99f5-fe9cc75e366a@kernel.org>
Date: Mon, 29 Sep 2025 08:09:12 +0200
From: Jiri Slaby <jirislaby@...nel.org>
To: Hugo Villeneuve <hugo@...ovil.com>, gregkh@...uxfoundation.org,
 fvallee@...rea.fr
Cc: linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
 Hugo Villeneuve <hvilleneuve@...onoff.com>
Subject: Re: [PATCH 05/15] serial: sc16is7xx: use guards for simple mutex
 locks

On 24. 09. 25, 17:37, Hugo Villeneuve wrote:
> --- a/drivers/tty/serial/sc16is7xx.c
> +++ b/drivers/tty/serial/sc16is7xx.c
...
> @@ -829,9 +827,6 @@ static bool sc16is7xx_port_irq(struct sc16is7xx_port *s, int portno)
>   		break;
>   	}
>   
> -out_port_irq:
> -	mutex_unlock(&one->lock);
> -
>   	return rc;

No need for rc now AFAICT.

>   }
>   
> @@ -874,9 +869,8 @@ static void sc16is7xx_tx_proc(struct kthread_work *ws)
>   	    (port->rs485.delay_rts_before_send > 0))
>   		msleep(port->rs485.delay_rts_before_send);
>   
> -	mutex_lock(&one->lock);
> +	guard(mutex)(&one->lock);
>   	sc16is7xx_handle_tx(port);
> -	mutex_unlock(&one->lock);
>   }
>   
>   static void sc16is7xx_reconf_rs485(struct uart_port *port)
> @@ -943,9 +937,8 @@ static void sc16is7xx_ms_proc(struct kthread_work *ws)
>   	struct sc16is7xx_port *s = dev_get_drvdata(one->port.dev);
>   
>   	if (one->port.state) {
> -		mutex_lock(&one->lock);
> +		guard(mutex)(&one->lock);
>   		sc16is7xx_update_mlines(one);
> -		mutex_unlock(&one->lock);
>   
>   		kthread_queue_delayed_work(&s->kworker, &one->ms_work, HZ);

Now the lock is held till here. R U sure it is OK?

thanks,
-- 
js
suse labs