linux-kernel - Re: [PATCH 3/3 v2] iio: add rtc-driver for HID sensors of type time

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Message-ID: <20121211103515.5ecfa0ae@pyramind.ukuu.org.uk>
Date:	Tue, 11 Dec 2012 10:35:15 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Alexander Holler <holler@...oftware.de>
Cc:	Lars-Peter Clausen <lars@...afoo.de>, linux-kernel@...r.kernel.org,
	linux-iio@...r.kernel.org, Jonathan Cameron <jic23@....ac.uk>,
	rtc-linux@...glegroups.com,
	Alessandro Zummo <a.zummo@...ertech.it>,
	srinivas pandruvada <srinivas.pandruvada@...el.com>
Subject: Re: [PATCH 3/3 v2] iio: add rtc-driver for HID sensors of type time

On Tue, 11 Dec 2012 01:01:29 +0100
Alexander Holler <holler@...oftware.de> wrote:

> Am 10.12.2012 23:36, schrieb Lars-Peter Clausen:
> > Well, I've been exaggerating a bit, you can call it multiple times, but you
> 
> Thanks a lot for the explanation(s).
> 
> >>>> +error_free_drvdata:
> >>>> +    platform_set_drvdata(pdev, NULL);
> >>>
> >>> Setting the platform data to NULL should not be necessary. Some
> >>> drivers do
> >>> this but it's kind of the result of cargo-cult-coding.
> >>>
> >>>> +    kfree(time_state);
> 
> Btw. I wouldn't call that cargo-cult-coding. It's more defensive 
> programming as people might not be sure, if there is something around 
> which still might access the platform data at that point. Ok, there 
> would be a need for a mutex or similiar if that really could happen, but 
> I wouldn't call such practices cargo-cult. ;)

Agreed - pointer NULLing catches a lot of mistakes during teardown where
timers or interrupts running in parallel get missed.

Alan
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