From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935102AbcA1Ka2 (ORCPT ); Thu, 28 Jan 2016 05:30:28 -0500 Received: from www.linutronix.de ([62.245.132.108]:58732 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932572AbcA1KaY (ORCPT ); Thu, 28 Jan 2016 05:30:24 -0500 Date: Thu, 28 Jan 2016 11:29:21 +0100 (CET) From: Thomas Gleixner To: Brian Starkey cc: linux-kernel@vger.kernel.org, marc.zyngier@arm.com Subject: Re: [PATCH] genirq: fix trigger flags check for shared irqs In-Reply-To: <20160128095955.GA12884@e106950-lin.cambridge.arm.com> Message-ID: References: <96c068ece0f5d01fc85bdbd9e0798f68180eebb8.1453204950.git.brian.starkey@arm.com> <20160128095955.GA12884@e106950-lin.cambridge.arm.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Brian, On Thu, 28 Jan 2016, Brian Starkey wrote: > On Tue, Jan 26, 2016 at 09:45:32PM +0100, Thomas Gleixner wrote: > > On Tue, 26 Jan 2016, Brian Starkey wrote: > > > > > For shared interrupts, if one requester passes in any IRQF_TRIGGER_* > > > flags whilst another doesn't, __setup_irq() can erroneously fail. > > > > > > The no-flags case should be treated as "already configured", so change > > > __setup_irq() to only check that the flags match if any have been > > > provided. > > > > What happens if that "already configured", i.e. the default setting, is > > conflicting with the newly requested interrupt? > > > > I rather prefer the failure than the resulting silent wreckage. > > > > Yes, I agree that would be best avoided. It seems to me that this case > is actually handled a bit lower down: > > } else if (new->flags & IRQF_TRIGGER_MASK) { > unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK; > unsigned int omsk = irq_settings_get_trigger_mask(desc); > > if (nmsk != omsk) > /* hope the handler works with current trigger mode > */ > pr_warning("irq %d uses trigger mode %u; requested > %u\n", > irq, nmsk, omsk); > } > > Perhaps that should be louder/fatal? Perhaps. So what's the actual problem case you are trying to solve? Thanks, tglx