linux-kernel - Re: [PATCH] genirq: warn about IRQF_SHARED|IRQF

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Date:	Mon, 30 Nov 2009 21:27:18 +0100
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	David Brownell <david-b@...bell.net>
Cc:	linux-kernel@...r.kernel.org,
	David Brownell <dbrownell@...rs.sourceforge.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>, Nicolas Pitre <nico@...vell.com>,
	Eric Miao <eric.y.miao@...il.com>,
	John Stultz <johnstul@...ibm.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Remy Bohmer <linux@...mer.net>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	Andrea Gallo <andrea.gallo@...ricsson.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jamie Lokier <jamie@...reable.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] genirq: warn about IRQF_SHARED|IRQF_DISABLED at the
	right place

On Mon, Nov 30, 2009 at 12:21:30PM -0800, David Brownell wrote:
> On Monday 30 November 2009, Uwe Kleine-König wrote:
> > +               if (new->flags & IRQF_DISABLED)
> > +                       pr_warning("IRQ %d/%s: IRQF_DISABLED is not guaranteed "
> > +                                       "on shared IRQs\n", irq, new->name);
> 
> This should have copied the original test ... this way,
> it's dropping the SHARED constraint, and trying to morph
> into a generic "IRQF_DISABLED is eeebil!" test.
No, it doesn't.  The inserted code is in an if block:

	old_ptr = &desc->action;
	old = *old_ptr;
	if (old) {
		/* ... */
		if (!((old->flags & new->flags) & IRQF_SHARED) ||
			((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
			old_name = old->name;
			goto mismatch;
		}

		...

+		if (new->flags & IRQF_DISABLED)
+			pr_warning("...");

and the mismatch label is further below.  So the warning is still only
hit if a shared irq is registered.

Best regards
Uwe

-- 
Pengutronix e.K.                              | Uwe Kleine-König            |
Industrial Linux Solutions                    | http://www.pengutronix.de/  |
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