linux-kernel - Re: ARM: OMAP2: Delete unnecessary checks before three function calls

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Date:	Thu, 16 Jul 2015 08:40:30 +0200
From:	SF Markus Elfring <elfring@...rs.sourceforge.net>
To:	Paul Walmsley <paul@...an.com>
Cc:	Benoît Cousson <bcousson@...libre.com>,
	Russell King <linux@....linux.org.uk>,
	Tony Lindgren <tony@...mide.com>,
	linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org,
	Julia Lawall <julia.lawall@...6.fr>
Subject: Re: ARM: OMAP2: Delete unnecessary checks before three function calls

> I have to say, I am a bit leery about applying the omap_device.c and
> omap_hwmod.c changes, since the called functions -- omap_device_delete()
> and clk_disable() -- don't explicitly document that NULLs are allowed
> to be passed in.

How are the chances to improve documentation around such implementation details?


> So there's no explicit contract that callers can rely upon, to (at least
> in theory) prevent those internal NULL pointer checks from being removed.

Are there any additional variations to consider for source files from different
processor architectures?


> So I would suggest that those two functions' kerneldoc be patched first to 
> explicitly state that passing in a NULL pointer is allowed.

Should my static source code analysis approach help you any more to clarify
further open issues?


> So I'll apply that change now for v4.3, touching up the commit message accordingly.

Thanks for your constructive feedback.


>>  arch/arm/mach-omap2/omap_device.c | 3 +--
>>  arch/arm/mach-omap2/omap_hwmod.c  | 5 +----
>>  arch/arm/mach-omap2/timer.c       | 3 +--

Did Tony Lindgren pick a similar update suggestion up, too?
https://lkml.org/lkml/2015/7/15/112

Regards,
Markus
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