linux-kernel - Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card

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Message-ID: <87si1rx96x.fsf@kamboji.qca.qualcomm.com>
Date:	Thu, 21 Jan 2016 17:07:34 +0200
From:	Kalle Valo <kvalo@...eaurora.org>
To:	Julia Lawall <julia.lawall@...6.fr>
Cc:	SF Markus Elfring <elfring@...rs.sourceforge.net>,
	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	libertas-dev@...ts.infradead.org, linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

Julia Lawall <julia.lawall@...6.fr> writes:

> On Sat, 2 Jan 2016, SF Markus Elfring wrote:
>
>> >> Move the jump label directly before the desired log statement
>> >> so that the variable "err" will not be checked once more
>> >> after it was determined that a function call failed.
>> >> Use the identifier "report_failure" instead of the label "err".
>> > 
>> >    Why?
>> 
>> I suggest to reconsider the places with which such a jump label
>> is connected.
>> 
>> 
>> > The code was smart enough
>> 
>> Which action should really be performed after a failure was detected
>> and handled a bit already?
>> 
>> * Another condition check
>> 
>> * Just additional error logging
>> 
>> 
>> > and you're making it uglier that it needs to be.
>> 
>> I assume that a software development taste can evolve, can't it?
>
> So far, you have gotten several down votes for this kind of change, and no 
> enthusiasm.
>
> Admittedly, this is a trivial case, because there are no local variables, 
> but do you actually know the semantics in C of a jump into a block?  And 
> if you do know, do you think that this semantics is common knowledge?  And 
> do you really think that introducing poorly understandable code is really 
> worth saving an if test of a single variable on a non-critical path?
>
> Most of the kernel code is not performance critical at the level of a 
> single if test.  So the goal should be for the code to be easy to 
> understand and robust to change.  The code that is performance critical, 
> you should probably not touch, ever.  The people who wrote it knew what 
> was important and what was not.

Very well said! Only optimise something you can measure.

I'm dropping this patch.

-- 
Kalle Valo