Re: [PATCH 2/4] arch/arm/mach-at91/clock.c: Add missing IS_ERR test

Ryan Mallon
2011-01-24T20:11:38Z

On 01/25/2011 09:05 AM, 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.

Julia is correct. Some architectures can return NULL from clk_get, but I
didn't check the at91 before posting :-/. If we can't return NULL from
clk_get then we shouldn't bother checking for it. I do think we should
drop the !IS_ERR(clk_get(dev, func)) check though.

~Ryan

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