linux-kernel - Re: [PATCH] iio/accel/bmc150: Improve unlocking of a mutex in two functions

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Message-ID: <c32ea2ea-5961-6589-6b51-1184d9565a38@users.sourceforge.net>
Date:   Wed, 25 Oct 2017 18:15:32 +0200
From:   SF Markus Elfring <elfring@...rs.sourceforge.net>
To:     Hans de Goede <hdegoede@...hat.com>, linux-iio@...r.kernel.org
Cc:     Hartmut Knaack <knaack.h@....de>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] iio/accel/bmc150: Improve unlocking of a mutex in two
 functions

> IMHO, if you do this, you should rework the function so that there is a single unlock call
> at the end, not a separate one in in error label.

Thanks for your update suggestion.

Does it indicate that I may propose similar source code adjustments
in this software area?


> Could e.g. change this:
> 
>         ret = bmc150_accel_set_power_state(data, false);
>         mutex_unlock(&data->mutex);
>         if (ret < 0)
>                 return ret;
> 
>         return IIO_VAL_INT;
> }
> 
> To:
> 
>         ret = bmc150_accel_set_power_state(data, false);
>         if (ret < 0)
>                 goto unlock;
> 
>     ret = IIO_VAL_INT;

How do you think about to use the following code variant then?

	if (!ret)
		ret = IIO_VAL_INT;


> unlock:
>         mutex_unlock(&data->mutex);
> 
>         return ret;
> }
> 
> And also use the unlock label in the other cases, this is actually
> quite a normal pattern. I see little use in a patch like this if there
> are still 2 unlock paths after the patch.

How long should I wait for corresponding feedback before another small
source code adjustment will be appropriate?

Regards,
Markus