linux-kernel - Re: [PATCH 12/15] sound: add missing HAS_IOPORT and GENERIC

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Date:	Wed, 13 Feb 2013 13:34:05 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Heiko Carstens <heiko.carstens@...ibm.com>,
	Takashi Iwai <tiwai@...e.de>, axboe@...nel.dk, cbou@...l.ru,
	davem@...emloft.net, dwmw2@...radead.org,
	grant.likely@...retlab.ca, gregkh@...uxfoundation.org,
	jkosina@...e.cz, jslaby@...e.cz, khali@...ux-fr.org,
	mchehab@...hat.com, perex@...ex.cz, sameo@...ux.intel.com,
	w.sang@...gutronix.de, linux-kernel@...r.kernel.org,
	sebott@...ux.vnet.ibm.com, gerald.schaefer@...ibm.com,
	schwidefsky@...ibm.com
Subject: Re: [PATCH 12/15] sound: add missing HAS_IOPORT and GENERIC_HARDIRQS
 dependencies

On Wed, Feb 06, 2013 at 09:56:55PM +0000, Arnd Bergmann wrote:
> On Wednesday 06 February 2013, Heiko Carstens wrote:
> > 
> > I haven't looked into it, but I doubt if that is possible without large
> > effort, if at all. s390 doesn't have any irq chips, nor something like
> > edge or level triggered irqs.
> > Instead we have floating interrupts. Does that fit into the concept of
> > GENERIC_HARDIRQS at all?
> > If so, we can give it a try, sure. But that won't happen any time soon.
> > 
> > Or are you simply proposing we should have both, our own irq handling plus
> > GENERIC_HARDIRQS with dummy functions?
> 
> I think you should use GENERIC_HARDIRQ just for PCI, and rename the s390
> interrupt handling to something that does not conflict. I understand
> that the concepts are quite different, but with PCI support, you actually
> do get all the weird interrupt hardware.
> More importantly, some features provided by GENERIC_HARDIRQ are replacing
> the traditional interfaces now, e.g. devm_request_irq() is actually
> recommended over request_irq() for normal drivers these days, as it
> simplifies the error handling.

I would be very careful with this statement. While devm_request_irq()
does simplify error handling in several cases I have also seen countless
examples when it was used with non devm_*-managed structures that are
freed by hand opening race window where interrupts can be delivered and
use structure that is already freed.

Thanks.

-- 
Dmitry
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