Date: Mon, 30 Nov 2009 15:43:29 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>,
       Rusty Russell <rusty@rustcorp.com.au>,
       David Brownell <dbrownell@users.sourceforge.net>,
       Eric Miao <eric.y.miao@gmail.com>,
       Andrea Gallo <andrea.gallo@stericsson.com>,
       Peter Zijlstra <peterz@infradead.org>,
       John Stultz <johnstul@us.ibm.com>, Nicolas Pitre <nico@marvell.com>,
       Jamie Lokier <jamie@shareable.org>, LKML <linux-kernel@vger.kernel.org>,
       Remy Bohmer <linux@bohmer.net>,
       Hugh Dickins <hugh.dickins@tiscali.co.uk>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= 
	<u.kleine-koenig@pengutronix.de>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Ingo Molnar <mingo@elte.hu>, linux-arm-kernel@lists.infradead.org
Subject: Re: Get rid of IRQF_DISABLED - (was [PATCH] genirq: warn about
	IRQF_SHARED|IRQF_DISABLED)
Message-ID: <20091130154329.GC7028@n2100.arm.linux.org.uk>
References: <1259356206-14843-1-git-send-email-u.kleine-koenig@pengutronix.de> <1259578067-29169-1-git-send-email-u.kleine-koenig@pengutronix.de> <alpine.LFD.2.00.0911301225110.24119@localhost.localdomain> <1259589780.26472.18.camel@laptop> <alpine.LFD.2.00.0911301519120.24119@localhost.localdomain> <20091130144702.14bea0ee@lxorguk.ukuu.org.uk> <20091130150100.GB7028@n2100.arm.linux.org.uk> <20091130153223.0e510a9b@lxorguk.ukuu.org.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20091130153223.0e510a9b@lxorguk.ukuu.org.uk>
User-Agent: Mutt/1.5.18 (2008-05-17)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1196
Lines: 27

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.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/