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

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Message-ID: <5688EBAC.5000701@gmail.com>
Date:	Sun, 3 Jan 2016 10:36:44 +0100
From:	Arend van Spriel <aspriel@...il.com>
To:	SF Markus Elfring <elfring@...rs.sourceforge.net>
Cc:	Julia Lawall <julia.lawall@...6.fr>,
	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	libertas-dev@...ts.infradead.org, linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org, Kalle Valo <kvalo@...eaurora.org>,
	LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org
Subject: Re: net-libertas: Better exception handling in
 if_spi_host_to_card_worker()



On 02-01-16 12:21, SF Markus Elfring wrote:
>> I have never seen much evolution going on in this area.
> 
> I can get an other impression from a specific document for example.
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/log/Documentation/CodingStyle
> 
> 
>> What the patch tries to do is avoid the extra 'if (err)'.
> 
> Yes. - I propose to look at related consequences together with the usage
> of a popular short jump label once more.

When I read a subject saying "Better exception handling" it sounds like
a functional improvement. Your change does not change anything
functionally and may or may not save a bit of execution time depending
on how smart the compiler is. What you change does is confuse people
reading the code. So please explain why your update improves exception
handling here. I don't see it. The code is not making the driver more
robust against failures in this function, which is what I think of
reading "better exception handling".

>> Setting coding style aside, the question is whether there is
>> a good metric for the patch.
> 
> A software development challenge is to accept changes also around a topic
> like "error handling". My update suggestion for the source file
> "drivers/net/wireless/marvell/libertas/if_spi.c" should only improve
> exception handling. (I came along other source files where more improvements
> will eventually be possible.)
> 
> When will the run-time behaviour matter also for exceptional situations?
> 
> 
>> Did you look at the resulting assembly code for different target architectures?
> 
> Not yet. - Which execution system variants would you recommend for
> further comparisons?

Guess x86{,_64} and arm would be good candidates, ie. CISC vs. RISC.

Regards,
Arend
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