linux-kernel - Re: [PATCH] input: ads7846: Switch to managed version of kzalloc and cleanups

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Message-ID: <20140728173154.GC8982@core.coreip.homeip.net>
Date:	Mon, 28 Jul 2014 10:31:54 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Pramod Gurav <pramod.gurav.etc@...il.com>
Cc:	linux-input@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Pramod Gurav <pramod.gurav@...rtplayin.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Mark Brown <broonie@...aro.org>,
	Fabio Estevam <fabio.estevam@...escale.com>
Subject: Re: [PATCH] input: ads7846: Switch to managed version of kzalloc and
 cleanups

On Mon, Jul 28, 2014 at 10:37:18PM +0530, Pramod Gurav wrote:
> Thanks Dmitry for reviewing.
> 
> On Mon, Jul 28, 2014 at 10:19 PM, Dmitry Torokhov
> <dmitry.torokhov@...il.com> wrote:
> > Hi Pramod,
> >
> > On Mon, Jul 28, 2014 at 02:16:55PM +0530, pramod.gurav.etc@...il.com wrote:
> >> From: Pramod Gurav <pramod.gurav@...rtplayin.com>
> >>
> >> This switches memory allocations from kzalloc to devm_kzalloc.
> >> This also changes the way return checks were done on failure cases
> >> of three allocations. The checks were clubbed together and hence
> >> must be done seperately to avoid calling kfree on unallocated memory.
> >>
> >> Moreover in case of input_allocate_device failure, we were calling
> >> input_free_device which is not needed.
> >
> > But not hurting either - like kfree() and many other "cleanup" functions
> > in kernel they are happily accept NULL input (so that cleanup code is
> > less branchy).
> >>
> Great. Good to learn.
> >> input device must be released(input_free_device) when ads7846_probe_dt
> >> fails hence adds a fix there as well.
> >
> > That is the real bug, could you send me a patch that fixes just that (by
> > jumping to err_free_mem)?
> Sure I will.
> 
> >
> > The rest I'd like to leave as is unless you can convert _all_ resources
> > to be managed ones: mixing up 2 styles (manual and automatic release) is
> > bound to have issues (like we had with ads7846_probe_dt which assumed
> > that since it was releasing its resources automatically the rest would
> > be released automatically as well.
> 
> I thought I would use a managed input_device allocation in a separate patch.
> I will convert all allocations to managed then.
> 
> This driver also registers a irq. You suggest to convert it to managed as well?
> I was planning to do that?

Yes. And regulators, gpios, sysfs (you might need to have custom action
for that) and chip cleanup. OTOH I do not see much value in these
conversions unless they make the code much more clean.

Thanks,

-- 
Dmitry
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