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Date:	Thu, 19 Sep 2013 06:33:37 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	"Zubair Lutfullah :" <zubair.lutfullah@...il.com>
CC:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-iio@...r.kernel.org, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, bigeasy@...utronix.de,
	gregkh@...uxfoundation.org
Subject: Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support



"Zubair Lutfullah :" <zubair.lutfullah@...il.com> wrote:
>On Wed, Sep 18, 2013 at 06:05:12PM +0100, Jonathan Cameron wrote:
>> 
>> >> >However in this case such conversion us dangerous. With all but
>IRQ
>> >> >resource managed by the traditional methods they will be released
>> >first
>> >> >with IRQ handler deregistered very last. Therefore if device is
>not
>> >> >properly quiesced IRQ raised during driver unbinding is likely to
>> >> >result
>> >> >in kernel oops.
>> >> >
>> >> >IOW devm_request_irq() is very often evil (it is still useful if
>> >_all_
>> >> >your resources are managed by devm_*).
>> >> >
>> >> >In case of your driver I'd recommend switching to
>> >> >request_irq()/free_irq() instead.
>> >> >
>> >> >Thanks.
>> >> 
>> >> Pretty much all resources are devm managed in here
>> >> 
>> >>
>>
>>https://git.kernel.org/cgit/linux/kernel/git/jic23/iio.git/tree/drivers/iio/adc/ti_am335x_adc.c?h=togreg&id=7a1aeba7ed0d5a1e83fd5a8ee2a2869430d40347
>> >
>> >
>> >So we are guaranteed that that new kfifo that is being allocated
>just
>> >before we requesting IRQ and will be freed way before we free the
>IRQ
>> >will not be used by the IOTQ handler?
>> >
>> >Thanks.
>> Good point. I forgot about that.  The source of interrupts 'should'
>be disabled before the kfifo is freed but I guess perhaps better to
>play it safe. Would take a fair bit of review to be sure that is not
>going to cause grief.
>> 
>> A few more devm handlers need writing before it is truly useful here.
>> 
>> Thanks for pointing this out.
>> 
>> J
>
>If I understand the conclusion correctly, no devm here?

No devm for the irq. The rest are fine.
>
>Zubair
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