linux-kernel - Re: [PATCH 5/9] clocksource/drivers/exynos_mct: Convert init function to return error

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Date:	Mon, 06 Jun 2016 13:28:57 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>, tglx@...utronix.de
Cc:	linux-kernel@...r.kernel.org, Kukjin Kim <kgene@...nel.org>,
	"moderated list:ARM/SAMSUNG EXYNO..." 
	<linux-arm-kernel@...ts.infradead.org>,
	"moderated list:ARM/SAMSUNG EXYNO..." 
	<linux-samsung-soc@...r.kernel.org>
Subject: Re: [PATCH 5/9] clocksource/drivers/exynos_mct: Convert init function
 to return error

On 06/06/2016 01:23 PM, Daniel Lezcano wrote:
> On 06/06/2016 12:51 PM, Krzysztof Kozlowski wrote:
>> On 06/01/2016 10:34 AM, Daniel Lezcano wrote:
>>> The init functions do not return any error. They behave as the
>>> following:
>>>
>>>   - panic, thus leading to a kernel crash while another timer may
>>> work and
>>>     make the system boot up correctly
>>>
>>>   or
>>>
>>>   - print an error and let the caller unaware if the state of the system
>>>
>>> Change that by converting the init functions to return an error
>>> conforming
>>> to the CLOCKSOURCE_OF_RET prototype.
>>>
>>> Proper error handling (rollback, errno value) will be changed later case
>>> by case, thus this change just return back an error or success in the
>>> init
>>> function.
>>
>> I don't see the benefits of this change alone. You are replacing one
>> non-return code to another always-return-success code. The effect is
>> exactly the same. It would make sense to change it to CLOCKSOURCE_OF_RET
>> along with proper error handling.
>>
> 
> Hi Krzysztof,
> 
> I can understand you expect an error handling but, as stated in the
> changelog, proper error handling will be done later. Currently, there
> are roughly 80 drivers to changes the init function to return a value in
> order change the CLOCKSOURCE_OF_DECLARE macro. That is a quite important
> number and changing also the internals will introduce bugs.
> 
> So the series (and there is a huge one coming right after this one),
> will focus only on changing the init function to return a value, so we
> can swap the clocksource table and rename CLOCKSOURCE_OF_DECLARE_RET
> without the '_RET'. I want this to be done before the next PR in order
> to prevent to have a double clksrc table.
> 
> If error handling is already taken into account and is trivial, I try to
> do the change, otherwise I let the function to return a success value.
> 
> Regarding the important number of drivers, if you have time to change
> the init function in the exynos_mct, that will be more than welcome :)

Ah, okay, you are planning to get rid of CLOCKSOURCE_OF_DECLARE. I
didn't receive the cover letter so the big picture remained hidden. Now
it looks good:

Reviewed-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>

Best regards,
Krzysztof