linux-kernel - Re: [PATCH 4/4] pinctrl/abx500: destroy mutex if returning early due to error

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Date:	Thu, 31 Jan 2013 10:28:26 -0700
From:	Stephen Warren <swarren@...dotorg.org>
To:	Lee Jones <lee.jones@...aro.org>
CC:	Linus Walleij <linus.walleij@...ricsson.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Stephen Warren <swarren@...dia.com>,
	Anmar Oueja <anmar.oueja@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH 4/4] pinctrl/abx500: destroy mutex if returning early
 due to error

On 01/31/2013 01:01 AM, Lee Jones wrote:
> On Wed, 30 Jan 2013, Stephen Warren wrote:
> 
>> On 01/30/2013 12:40 PM, Linus Walleij wrote:
>>> From: Lee Jones <lee.jones@...aro.org>
>>>
>>> Current failure path neglects to mutex_destroy() before returning
>>> an error due to an invalid parameter or an error received from
>>> gpiochip_add(). This patch aims to remedy that behaviour.
>>
>>> diff --git a/drivers/pinctrl/pinctrl-abx500.c b/drivers/pinctrl/pinctrl-abx500.c
>>
>>> @@ -1155,11 +1155,13 @@ static int abx500_gpio_probe(struct platform_device *pdev)
>>>  	default:
>>>  		dev_err(&pdev->dev, "Unsupported pinctrl sub driver (%d)\n",
>>>  				(int) platid->driver_data);
>>> +		mutex_destroy(&pct->lock);
>>>  		return -EINVAL;
>>
>> Especially given there's already a label out_free which performs this
>> mutex_destroy(), those last two lines would be better as:
>>
>> ret = -EINVAL;
>> goto out_free;
> 
> Yes, that's one way of doing it. I figured it was 6 of one and half a
> dozen of the other to be honest.
> 
> Either I:
> 
>  +           mutex_destroy(&pct->lock);
> 
> Or:
> 
>  +           ret = -EINVAL; 
>  +           goto out_free;
>  -           return -EINVAL;
> 
> I figured the smallest diff would be best. To be honest, I'm not
> bothered either way. If it offends you, I can do it the other way, no
> problem. Just let me know quick, so I can get the fixed up patch to
> Linus.
> 
> NB: There is no 'out_free:' at this point, it has already been
> removed.

Where has it been removed? Both the latest linux-next and LinusW's
pinctrl tree on git.kernel.org still contain it...

The style in that code is clearly "goto foo" for error-handling, and
makes for smaller simpler code, so I don't see why the label would be
removed.

Still, this review is just a suggestion; this driver isn't anything I
have any ownership of, so I guess feel free to go either way.
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