linux-kernel - Re: [PATCH] staging: iio: ad7746: Improve unlocking of a mutex in ad7746_start

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Date:   Sun, 19 Nov 2017 15:37:30 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     SF Markus Elfring <elfring@...rs.sourceforge.net>
Cc:     devel@...verdev.osuosl.org, linux-iio@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] staging: iio: ad7746: Improve unlocking of a mutex in
 ad7746_start_calib()

On Fri, 3 Nov 2017 09:33:57 +0100
SF Markus Elfring <elfring@...rs.sourceforge.net> wrote:

> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Fri, 3 Nov 2017 09:26:28 +0100
> 
> * Add a jump target so that a call of the function "mutex_unlock" is stored
>   only twice in this function implementation.
> 
> * Replace two calls by goto statements.
> 
> This issue was detected by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
Again, a reasonable little tidy up. Applied to the togreg branch
of iio.git and pushed out as testing for the autobuilders to check
we haven't missed anything.

Thanks,

Jonathan
> ---
>  drivers/staging/iio/cdc/ad7746.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c
> index a124853a05f0..c4a864725376 100644
> --- a/drivers/staging/iio/cdc/ad7746.c
> +++ b/drivers/staging/iio/cdc/ad7746.c
> @@ -302,23 +302,24 @@ static inline ssize_t ad7746_start_calib(struct device *dev,
>  	mutex_lock(&chip->lock);
>  	regval |= chip->config;
>  	ret = i2c_smbus_write_byte_data(chip->client, AD7746_REG_CFG, regval);
> -	if (ret < 0) {
> -		mutex_unlock(&chip->lock);
> -		return ret;
> -	}
> +	if (ret < 0)
> +		goto unlock;
>  
>  	do {
>  		msleep(20);
>  		ret = i2c_smbus_read_byte_data(chip->client, AD7746_REG_CFG);
> -		if (ret < 0) {
> -			mutex_unlock(&chip->lock);
> -			return ret;
> -		}
> +		if (ret < 0)
> +			goto unlock;
> +
>  	} while ((ret == regval) && timeout--);
>  
>  	mutex_unlock(&chip->lock);
>  
>  	return len;
> +
> +unlock:
> +	mutex_unlock(&chip->lock);
> +	return ret;
>  }
>  
>  static ssize_t ad7746_start_offset_calib(struct device *dev,