From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: [PATCH v2 00/26] genirq: fix use of irq_find_mapping outside of legal RCU context Date: Wed, 3 Sep 2014 14:09:42 +0200 (CEST) Message-ID: References: <1409047421-27649-1-git-send-email-marc.zyngier@arm.com> <87y4uap98n.fsf@approximate.cambridge.arm.com> <20140903120406.GK30467@titan.lakedaemon.net> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from www.linutronix.de ([62.245.132.108]:43897 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932075AbaICMJ6 (ORCPT ); Wed, 3 Sep 2014 08:09:58 -0400 In-Reply-To: <20140903120406.GK30467@titan.lakedaemon.net> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Jason Cooper Cc: Marc Zyngier , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-omap@vger.kernel.org" , "linux@openrisc.net" , "linux@arm.linux.org.uk" , "shawn.guo@freescale.com" , "kernel@pengutronix.de" , "tony@atomide.com" , Catalin Marinas , Will Deacon , "jonas@southpole.se" , "shc_work@mail.ru" , "baohua@kernel.org" , "maxime.ripard@free-electrons.com" , "khilman@linaro.org" , "sboyd@codeaurora.org" , Lorenzo Pieralisi On Wed, 3 Sep 2014, Jason Cooper wrote: > On Wed, Aug 27, 2014 at 10:33:44AM +0100, Marc Zyngier wrote: > > Hi Thomas, > > > > On Tue, Aug 26 2014 at 10:34:51 pm BST, Thomas Gleixner wrote: > > > On Tue, 26 Aug 2014, Marc Zyngier wrote: > > > > > >> A number of irqchip drivers are directly calling irq_find_mapping, > > >> which may use a rcu_read_lock call when walking the radix tree. > > >> > > >> Turns out that if you hit that point with CONFIG_PROVE_RCU enabled, > > >> the kernel will shout at you, as using RCU in this context may be > > >> illegal (specially if coming from the idle state, where RCU would be > > >> in a quiescent state). > > >> > > >> A possible fix would be to wrap calls to irq_find_mapping into a > > >> RCU_NONIDLE macro, but that really looks ugly. > > >> > > >> This patch series introduce another generic IRQ entry point > > >> (handle_domain_irq), which has the exact same behaviour as handle_IRQ > > >> (as defined on arm, arm64 and openrisc), except that it also takes a > > >> irq_domain pointer. This allows the logical IRQ lookup to be done > > >> inside the irq_{enter,exit} section, which contains a > > >> rcu_irq_{enter,exit}, making it safe. > > > > > > Looks good. Should this be routed to the genirq tree? > > > > I'm happy for you to take this series, provided the architecture > > maintainers agree on it (I'm still to hear from the openrisc guys, and > > their mailing-list seems to positively hate my guts). > > I think everyone's had a chance to look over it by now. Thomas, shall I > take the series? Yes please.