From mboxrd@z Thu Jan  1 00:00:00 1970
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
Date: Mon, 30 Nov 2009 15:43:29 +0000
Subject: Get rid of IRQF_DISABLED - (was [PATCH] genirq: warn about
	IRQF_SHARED|IRQF_DISABLED)
In-Reply-To: <20091130153223.0e510a9b@lxorguk.ukuu.org.uk>
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	<alpine.LFD.2.00.0911301519120.24119@localhost.localdomain>
	<20091130144702.14bea0ee@lxorguk.ukuu.org.uk>
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	<20091130153223.0e510a9b@lxorguk.ukuu.org.uk>
Message-ID: <20091130154329.GC7028@n2100.arm.linux.org.uk>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, Nov 30, 2009 at 03:32:23PM +0000, Alan Cox wrote:
> On Mon, 30 Nov 2009 15:01:00 +0000
> Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
> > On Mon, Nov 30, 2009 at 02:47:02PM +0000, Alan Cox wrote:
> > > SHARED|DISABLED ought to WARN_ON() and if that doesn't motivate people
> > > then return -EINVAL.
> > 
> > That is an impossibility.  There is hardware out there (AT91) where
> > the timer interrupt is shared with other peripherals, and you end
> > up with a mixture of irqs-disabled and irqs-enabled handlers sharing
> > the same interrupt.
> 
> Well that will encourage people to fix it.
> 
> > My point is that if we outlaw irqs-disabled shared interrupts, it puts
> > Atmel AT91 support into immediate difficulties.
> 
> If a driver disables the timer irq across a tick aren't you already in
> trouble ?

Not with this clockevents code - you can miss timer interrupts and the core
time keeping code catches up automatically.