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

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Message-ID: <CAKdAkRRLk8rHyUw_fAGpNu_u8wkNyL2kDqFQ-=bigefkXqUcxA@mail.gmail.com>
Date:	Fri, 6 Mar 2015 11:41:45 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Hannes Reinecke <hare@...e.de>
Cc:	Valentin Rothberg <valentinrothberg@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	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>,
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	Eyal Perry <eyalpe@...lanox.com>,
	Arnd Bergmann <arnd@...db.de>,
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	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>,
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	iss_storagedev@...com, linux-mtd@...ts.infradead.org,
	linux-usb@...r.kernel.org
Subject: Re: [PATCH] Remove deprecated IRQF_DISABLED flag entirely

On Thu, Mar 5, 2015 at 5:11 AM, Hannes Reinecke <hare@...e.de> wrote:
> 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.

No, that would imply that IRQ never triggers whereas passing 0 means
we keep triggers that have been set by the platform.

Thanks.

-- 
Dmitry
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