linux-kernel - Re: [PATCH] Remove deprecated IRQF

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Date:	Thu, 05 Mar 2015 14:11:00 +0100
From:	Hannes Reinecke <hare@...e.de>
To:	Valentin Rothberg <valentinrothberg@...il.com>,
	akpm@...ux-foundation.org
CC:	Jonathan Corbet <corbet@....net>,
	Ralf Baechle <ralf@...ux-mips.org>,
	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Paul Bolle <pebolle@...cali.nl>, Jiri Kosina <jkosina@...e.cz>,
	Ewan Milne <emilne@...hat.com>, Christoph Hellwig <hch@....de>,
	Huacai Chen <chenhc@...ote.com>,
	Hongliang Tao <taohl@...ote.com>, Nishanth Menon <nm@...com>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Peter Ujfalusi <peter.ujfalusi@...com>,
	Tony Lindgren <tony@...mide.com>,
	Rajendra Nayak <rnayak@...com>,
	Sricharan R <r.sricharan@...com>,
	Afzal Mohammed <afzal@...com>, Keerthy <j-keerthy@...com>,
	Dan Carpenter <dan.carpenter@...cle.com>,
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	Thomas Gleixner <tglx@...utronix.de>,
	Randy Dunlap <rdunlap@...radead.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Quentin Lambert <lambert.quentin@...il.com>,
	Eyal Perry <eyalpe@...lanox.com>,
	Arnd Bergmann <arnd@...db.de>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mips@...ux-mips.org, iss_storagedev@...com,
	linux-mtd@...ts.infradead.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH] Remove deprecated IRQF_DISABLED flag entirely

On 03/05/2015 01:59 PM, Valentin Rothberg wrote:
> The IRQF_DISABLED is a NOOP and has been scheduled for removal since
> Linux v2.6.36 by commit 6932bf37bed4 ("genirq: Remove IRQF_DISABLED from
> core code").
> 
> According to commit e58aa3d2d0cc ("genirq: Run irq handlers with
> interrupts disabled") running IRQ handlers with interrupts enabled can
> cause stack overflows when the interrupt line of the issuing device is
> still active.
> 
> This patch ends the grace period for IRQF_DISABLED (i.e., SA_INTERRUPT
> in older versions of Linux) and removes the definition and all remaining
> usages of this flag.
> 
> Signed-off-by: Valentin Rothberg <valentinrothberg@...il.com>
> ---
> The bigger hunk in Documentation/scsi/ncr53c8xx.txt is removed entirely
> as IRQF_DISABLED is gone now; the usage in older kernel versions
> (including the old SA_INTERRUPT flag) should be discouraged.  The
> trouble of using IRQF_SHARED is a general problem and not specific to
> any driver.
> 
> I left the reference in Documentation/PCI/MSI-HOWTO.txt untouched since
> it has already been removed in linux-next by commit b0e1ee8e1405
> ("MSI-HOWTO.txt: remove reference on IRQF_DISABLED").
> 
> All remaining references are changelogs that I suggest to keep.

While you're at it: having '0x0' as a value for the irq flags looks
a bit silly, and makes you wonder what the parameter is for.

I would rather like to have

#define IRQF_NONE 0x0

and use it for these cases.
That way the scope of that parameter is clear.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		               zSeries & Storage
hare@...e.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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