linux-kernel - Re: [PATCH 2/4] arch/arm/mach-at91/clock.c: Add missing IS

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Message-ID: <4D3EA6EC.5050305@bfs.de>
Date:	Tue, 25 Jan 2011 11:33:16 +0100
From:	walter harms <wharms@....de>
To:	Julia Lawall <julia@...u.dk>
CC:	Vasiliy Kulikov <segooon@...il.com>,
	Ryan Mallon <ryan@...ewatersys.com>,
	Russell King <linux@....linux.org.uk>,
	kernel-janitors@...r.kernel.org,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
	Andrew Victor <linux@...im.org.za>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] arch/arm/mach-at91/clock.c: Add missing IS_ERR test



Am 24.01.2011 21:09, schrieb Julia Lawall:
> On Mon, 24 Jan 2011, Vasiliy Kulikov wrote:
> 
>> On Mon, Jan 24, 2011 at 21:00 +0100, Julia Lawall wrote:
>>> On Tue, 25 Jan 2011, Ryan Mallon wrote:
>>>
>>>> On 01/25/2011 08:55 AM, Julia Lawall wrote:
>>>>> @@ -224,7 +224,7 @@ void __init at91_clock_associate(const char *id, struct device *dev, const char
>>>>>  {
>>>>>  	struct clk *clk = clk_get(NULL, id);
>>>>>  
>>>>> -	if (!dev || !clk || !IS_ERR(clk_get(dev, func)))
>>>>> +	if (!dev || IS_ERR(clk) || !IS_ERR(clk_get(dev, func)))
>>>>>  		return;
>>>>
>>>> I think we want:
>>>>
>>>> 	if (!dev || !clk || IS_ERR(clk) || !IS_ERR(clk_get(dev, func)))
>>>> 		return;
>>>>
>>>> Since it is valid to return a NULL clk, and we don't want to try and
>>>> dereference it if that is the case.
>>>
>>> Looking at the given defintion of clk_get, I can't see how that could 
>>> happen:
>>
>> clk_get() is defined per-architecture, sometimes it is NULL only.
> 
> In this case there is a definition in the same file, so it doesn't seem 
> necessary to worry about possible other ones.  Unless there is some goal 
> in the future to remove the local one?
> 

Would it be more easy to return NULL in the error case of clk_get() instead
of ERR_PTR(-ENOENT) ?

So the default could be return NULL and an architecture depending solution
replacing that.

re,
 wh
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