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

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Date:	Thu, 16 Jul 2015 14:06:44 +0000 (UTC)
From:	Paul Walmsley <paul@...an.com>
To:	Tony Lindgren <tony@...mide.com>
cc:	SF Markus Elfring <elfring@...rs.sourceforge.net>,
	Benoît Cousson <bcousson@...libre.com>,
	Russell King <linux@....linux.org.uk>,
	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: [PATCH] ARM: OMAP2: Delete unnecessary checks before three
 function calls

On Wed, 15 Jul 2015, Tony Lindgren wrote:

> * Paul Walmsley <paul@...an.com> [150715 22:58]:
> > Hello Markus
> > 
> > On Tue, 30 Jun 2015, SF Markus Elfring wrote:
> > 
> > > From: Markus Elfring <elfring@...rs.sourceforge.net>
> > > Date: Tue, 30 Jun 2015 14:00:16 +0200
> > > 
> > > The functions clk_disable(), of_node_put() and omap_device_delete() test
> > > whether their argument is NULL and then return immediately.
> > > Thus the test around the call is not needed.
> > > 
> > > This issue was detected by using the Coccinelle software.
> > > 
> > > Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> > 
> > Thanks for the patch.  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.  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.
> > 
> > So I would suggest that those two functions' kerneldoc be patched first to 
> > explicitly state that passing in a NULL pointer is allowed.  Then I would 
> > feel a bit more comfortable applying the omap_device.c and omap_hwmod.c 
> > changes.
> > 
> > The kerneldoc for of_node_put() does explicitly allow NULLs to be passed 
> > in.  So I'll apply that change now for v4.3, touching up the commit 
> > message accordingly.
> 
> I have them applied from a later thread already, but will drop both in
> my branch as I have not pushed them out yet.

Oops sorry about stepping on your toes - I obviously missed that followup.

- Paul
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