linux-kernel - Re: [PATCH 12/22] Input: iqs269a - use guard notation when acquiring mutex

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Message-ID: <Zt4fsJI4SFhBo5ZX@nixie71>
Date: Sun, 8 Sep 2024 17:05:36 -0500
From: Jeff LaBundy <jeff@...undy.com>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: linux-input@...r.kernel.org,
	Michael Hennerich <michael.hennerich@...log.com>,
	Ville Syrjala <syrjala@....fi>,
	Support Opensource <support.opensource@...semi.com>,
	Eddie James <eajames@...ux.ibm.com>,
	Andrey Moiseev <o2g.org.ru@...il.com>,
	Hans de Goede <hdegoede@...hat.com>,
	Javier Carrasco <javier.carrasco.cruz@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/22] Input: iqs269a - use guard notation when acquiring
 mutex

Hi Dmitry,

On Tue, Sep 03, 2024 at 09:47:55PM -0700, Dmitry Torokhov wrote:
> Using guard notation 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>

Reviewed-by: Jeff LaBundy <jeff@...undy.com>

> ---
>  drivers/input/misc/iqs269a.c | 46 +++++++++++++-----------------------
>  1 file changed, 16 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/input/misc/iqs269a.c b/drivers/input/misc/iqs269a.c
> index 843f8a3f3410..c34d847fa4af 100644
> --- a/drivers/input/misc/iqs269a.c
> +++ b/drivers/input/misc/iqs269a.c
> @@ -365,7 +365,7 @@ static int iqs269_ati_mode_set(struct iqs269_private *iqs269,
>  	if (mode > IQS269_CHx_ENG_A_ATI_MODE_MAX)
>  		return -EINVAL;
>  
> -	mutex_lock(&iqs269->lock);
> +	guard(mutex)(&iqs269->lock);
>  
>  	engine_a = be16_to_cpu(ch_reg[ch_num].engine_a);
>  
> @@ -375,8 +375,6 @@ static int iqs269_ati_mode_set(struct iqs269_private *iqs269,
>  	ch_reg[ch_num].engine_a = cpu_to_be16(engine_a);
>  	iqs269->ati_current = false;
>  
> -	mutex_unlock(&iqs269->lock);
> -
>  	return 0;
>  }
>  
> @@ -389,9 +387,9 @@ static int iqs269_ati_mode_get(struct iqs269_private *iqs269,
>  	if (ch_num >= IQS269_NUM_CH)
>  		return -EINVAL;
>  
> -	mutex_lock(&iqs269->lock);
> +	guard(mutex)(&iqs269->lock);
> +
>  	engine_a = be16_to_cpu(ch_reg[ch_num].engine_a);
> -	mutex_unlock(&iqs269->lock);
>  
>  	engine_a &= IQS269_CHx_ENG_A_ATI_MODE_MASK;
>  	*mode = (engine_a >> IQS269_CHx_ENG_A_ATI_MODE_SHIFT);
> @@ -429,7 +427,7 @@ static int iqs269_ati_base_set(struct iqs269_private *iqs269,
>  		return -EINVAL;
>  	}
>  
> -	mutex_lock(&iqs269->lock);
> +	guard(mutex)(&iqs269->lock);
>  
>  	engine_b = be16_to_cpu(ch_reg[ch_num].engine_b);
>  
> @@ -439,8 +437,6 @@ static int iqs269_ati_base_set(struct iqs269_private *iqs269,
>  	ch_reg[ch_num].engine_b = cpu_to_be16(engine_b);
>  	iqs269->ati_current = false;
>  
> -	mutex_unlock(&iqs269->lock);
> -
>  	return 0;
>  }
>  
> @@ -453,9 +449,9 @@ static int iqs269_ati_base_get(struct iqs269_private *iqs269,
>  	if (ch_num >= IQS269_NUM_CH)
>  		return -EINVAL;
>  
> -	mutex_lock(&iqs269->lock);
> +	guard(mutex)(&iqs269->lock);
> +
>  	engine_b = be16_to_cpu(ch_reg[ch_num].engine_b);
> -	mutex_unlock(&iqs269->lock);
>  
>  	switch (engine_b & IQS269_CHx_ENG_B_ATI_BASE_MASK) {
>  	case IQS269_CHx_ENG_B_ATI_BASE_75:
> @@ -491,7 +487,7 @@ static int iqs269_ati_target_set(struct iqs269_private *iqs269,
>  	if (target > IQS269_CHx_ENG_B_ATI_TARGET_MAX)
>  		return -EINVAL;
>  
> -	mutex_lock(&iqs269->lock);
> +	guard(mutex)(&iqs269->lock);
>  
>  	engine_b = be16_to_cpu(ch_reg[ch_num].engine_b);
>  
> @@ -501,8 +497,6 @@ static int iqs269_ati_target_set(struct iqs269_private *iqs269,
>  	ch_reg[ch_num].engine_b = cpu_to_be16(engine_b);
>  	iqs269->ati_current = false;
>  
> -	mutex_unlock(&iqs269->lock);
> -
>  	return 0;
>  }
>  
> @@ -515,10 +509,9 @@ static int iqs269_ati_target_get(struct iqs269_private *iqs269,
>  	if (ch_num >= IQS269_NUM_CH)
>  		return -EINVAL;
>  
> -	mutex_lock(&iqs269->lock);
> -	engine_b = be16_to_cpu(ch_reg[ch_num].engine_b);
> -	mutex_unlock(&iqs269->lock);
> +	guard(mutex)(&iqs269->lock);
>  
> +	engine_b = be16_to_cpu(ch_reg[ch_num].engine_b);
>  	*target = (engine_b & IQS269_CHx_ENG_B_ATI_TARGET_MASK) * 32;
>  
>  	return 0;
> @@ -1199,7 +1192,7 @@ static int iqs269_dev_init(struct iqs269_private *iqs269)
>  {
>  	int error;
>  
> -	mutex_lock(&iqs269->lock);
> +	guard(mutex)(&iqs269->lock);
>  
>  	/*
>  	 * Early revisions of silicon require the following workaround in order
> @@ -1210,19 +1203,19 @@ static int iqs269_dev_init(struct iqs269_private *iqs269)
>  		error = regmap_multi_reg_write(iqs269->regmap, iqs269_tws_init,
>  					       ARRAY_SIZE(iqs269_tws_init));
>  		if (error)
> -			goto err_mutex;
> +			return error;
>  	}
>  
>  	error = regmap_update_bits(iqs269->regmap, IQS269_HALL_UI,
>  				   IQS269_HALL_UI_ENABLE,
>  				   iqs269->hall_enable ? ~0 : 0);
>  	if (error)
> -		goto err_mutex;
> +		return error;
>  
>  	error = regmap_raw_write(iqs269->regmap, IQS269_SYS_SETTINGS,
>  				 &iqs269->sys_reg, sizeof(iqs269->sys_reg));
>  	if (error)
> -		goto err_mutex;
> +		return error;
>  
>  	/*
>  	 * The following delay gives the device time to deassert its RDY output
> @@ -1232,10 +1225,7 @@ static int iqs269_dev_init(struct iqs269_private *iqs269)
>  
>  	iqs269->ati_current = true;
>  
> -err_mutex:
> -	mutex_unlock(&iqs269->lock);
> -
> -	return error;
> +	return 0;
>  }
>  
>  static int iqs269_input_init(struct iqs269_private *iqs269)
> @@ -1580,13 +1570,11 @@ static ssize_t hall_enable_store(struct device *dev,
>  	if (error)
>  		return error;
>  
> -	mutex_lock(&iqs269->lock);
> +	guard(mutex)(&iqs269->lock);
>  
>  	iqs269->hall_enable = val;
>  	iqs269->ati_current = false;
>  
> -	mutex_unlock(&iqs269->lock);
> -
>  	return count;
>  }
>  
> @@ -1643,13 +1631,11 @@ static ssize_t rx_enable_store(struct device *dev,
>  	if (val > 0xFF)
>  		return -EINVAL;
>  
> -	mutex_lock(&iqs269->lock);
> +	guard(mutex)(&iqs269->lock);
>  
>  	ch_reg[iqs269->ch_num].rx_enable = val;
>  	iqs269->ati_current = false;
>  
> -	mutex_unlock(&iqs269->lock);
> -
>  	return count;
>  }
>  
> -- 
> 2.46.0.469.g59c65b2a67-goog
> 

Kind regards,
Jeff LaBundy