linux-kernel - Re: iio/gyro/bmg160_core: Improve unlocking of a mutex in five functions

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Message-ID: <73f0a187-57d1-c877-ba9f-3b15f6a61640@users.sourceforge.net>
Date:   Sun, 18 Mar 2018 09:19:47 +0100
From:   SF Markus Elfring <elfring@...rs.sourceforge.net>
To:     Jonathan Cameron <jic23@...nel.org>, linux-iio@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Pravin Shedge <pravin.shedge4linux@...il.com>,
        Quentin Schulz <quentin.schulz@...e-electrons.com>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: iio/gyro/bmg160_core: Improve unlocking of a mutex in five
 functions



Am 17.03.2018 um 20:54 schrieb Jonathan Cameron:
> On Wed, 14 Mar 2018 16:15:32 +0100
> SF Markus Elfring <elfring@...rs.sourceforge.net> wrote:
> 
>> From: Markus Elfring <elfring@...rs.sourceforge.net>
>> Date: Wed, 14 Mar 2018 16:06:49 +0100
>>
>> * Add jump targets so that a call of the function "mutex_unlock" is stored
>>   only once in these function implementations.
>>
>> * Replace 19 calls by goto statements.
>>
>> This issue was detected by using the Coccinelle software.
>>
>> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> 
> Hi Markus,
> 
> Some of these are good and sensible changes

Such feedback is nice.


> - others break the code.

Which concrete places do you find questionable here?


>> -		return ret;
>> +
>> +		goto set_power_state;
>>  	default:
>>  		return -EINVAL;
> We exit with the mutex locked now and it should not be.

I wonder about your source code interpretation here.
The mutex was (and is still only) locked within case branches, isn't it?


> 
>>  	}
>>  
>>  	return -EINVAL;
> Mutex is still locked here and the return is wrong.

Should this statement get any more software development attention?

Regards,
Markus