linux-kernel - Re: [PATCH 03/17] Input: atkbd - use guard notation when acquiring mutex

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Message-ID: <c32467c6-fe3d-4ac9-85cb-15f37d4728a2@redhat.com>
Date: Sun, 25 Aug 2024 15:12:57 +0200
From: Hans de Goede <hdegoede@...hat.com>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>, linux-input@...r.kernel.org
Cc: Michael Hennerich <michael.hennerich@...log.com>,
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>, Laxman Dewangan <ldewangan@...dia.com>,
 Thierry Reding <thierry.reding@...il.com>, Tony Lindgren <tony@...mide.com>,
 Jeff LaBundy <jeff@...undy.com>, linux-kernel@...r.kernel.org,
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 linux-tegra@...r.kernel.org
Subject: Re: [PATCH 03/17] Input: atkbd - use guard notation when acquiring
 mutex

Hi,

On 8/25/24 7:16 AM, Dmitry Torokhov wrote:
> This makes the code more compact and error handling more robust
> by ensuring that mutexes are released in all code paths when control
> leaves critical section.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

Thanks, patch looks good to me:

Reviewed-by: Hans de Goede <hdegoede@...hat.com>

Regards,

Hans



> ---
>  drivers/input/keyboard/atkbd.c | 37 ++++++++++++++--------------------
>  1 file changed, 15 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c
> index f4f2078cf501..5855d4fc6e6a 100644
> --- a/drivers/input/keyboard/atkbd.c
> +++ b/drivers/input/keyboard/atkbd.c
> @@ -639,7 +639,7 @@ static void atkbd_event_work(struct work_struct *work)
>  {
>  	struct atkbd *atkbd = container_of(work, struct atkbd, event_work.work);
>  
> -	mutex_lock(&atkbd->mutex);
> +	guard(mutex)(&atkbd->mutex);
>  
>  	if (!atkbd->enabled) {
>  		/*
> @@ -657,8 +657,6 @@ static void atkbd_event_work(struct work_struct *work)
>  		if (test_and_clear_bit(ATKBD_REP_EVENT_BIT, &atkbd->event_mask))
>  			atkbd_set_repeat_rate(atkbd);
>  	}
> -
> -	mutex_unlock(&atkbd->mutex);
>  }
>  
>  /*
> @@ -1361,7 +1359,7 @@ static int atkbd_reconnect(struct serio *serio)
>  {
>  	struct atkbd *atkbd = atkbd_from_serio(serio);
>  	struct serio_driver *drv = serio->drv;
> -	int retval = -1;
> +	int error;
>  
>  	if (!atkbd || !drv) {
>  		dev_dbg(&serio->dev,
> @@ -1369,16 +1367,17 @@ static int atkbd_reconnect(struct serio *serio)
>  		return -1;
>  	}
>  
> -	mutex_lock(&atkbd->mutex);
> +	guard(mutex)(&atkbd->mutex);
>  
>  	atkbd_disable(atkbd);
>  
>  	if (atkbd->write) {
> -		if (atkbd_probe(atkbd))
> -			goto out;
> +		error = atkbd_probe(atkbd);
> +		if (error)
> +			return error;
>  
>  		if (atkbd->set != atkbd_select_set(atkbd, atkbd->set, atkbd->extra))
> -			goto out;
> +			return -EIO;
>  
>  		/*
>  		 * Restore LED state and repeat rate. While input core
> @@ -1404,11 +1403,7 @@ static int atkbd_reconnect(struct serio *serio)
>  	if (atkbd->write)
>  		atkbd_activate(atkbd);
>  
> -	retval = 0;
> -
> - out:
> -	mutex_unlock(&atkbd->mutex);
> -	return retval;
> +	return 0;
>  }
>  
>  static const struct serio_device_id atkbd_serio_ids[] = {
> @@ -1465,17 +1460,15 @@ static ssize_t atkbd_attr_set_helper(struct device *dev, const char *buf, size_t
>  	struct atkbd *atkbd = atkbd_from_serio(serio);
>  	int retval;
>  
> -	retval = mutex_lock_interruptible(&atkbd->mutex);
> -	if (retval)
> -		return retval;
> +	scoped_guard(mutex_intr, &atkbd->mutex) {
> +		atkbd_disable(atkbd);
> +		retval = handler(atkbd, buf, count);
> +		atkbd_enable(atkbd);
>  
> -	atkbd_disable(atkbd);
> -	retval = handler(atkbd, buf, count);
> -	atkbd_enable(atkbd);
> -
> -	mutex_unlock(&atkbd->mutex);
> +		return retval;
> +	}
>  
> -	return retval;
> +	return -EINTR;
>  }
>  
>  static ssize_t atkbd_show_extra(struct atkbd *atkbd, char *buf)