From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F0E84C433F5 for ; Fri, 22 Oct 2021 15:05:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC7566112F for ; Fri, 22 Oct 2021 15:05:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233239AbhJVPH5 (ORCPT ); Fri, 22 Oct 2021 11:07:57 -0400 Received: from foss.arm.com ([217.140.110.172]:55436 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233069AbhJVPHz (ORCPT ); Fri, 22 Oct 2021 11:07:55 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9A3F31FB; Fri, 22 Oct 2021 08:05:37 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.73.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BB3533F694; Fri, 22 Oct 2021 08:05:32 -0700 (PDT) Date: Fri, 22 Oct 2021 16:05:24 +0100 From: Mark Rutland To: Marc Zyngier Cc: linux-kernel@vger.kernel.org, aou@eecs.berkeley.edu, catalin.marinas@arm.com, deanbo422@gmail.com, green.hu@gmail.com, guoren@kernel.org, jonas@southpole.se, kernelfans@gmail.com, linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk, nickhu@andestech.com, palmer@dabbelt.com, paulmck@kernel.org, paul.walmsley@sifive.com, peterz@infradead.org, shorne@gmail.com, stefan.kristiansson@saunalahti.fi, tglx@linutronix.de, torvalds@linux-foundation.org, tsbogend@alpha.franken.de, vgupta@kernel.org, will@kernel.org Subject: Re: [PATCH 01/15] irq: mips: avoid nested irq_enter() Message-ID: <20211022150524.GA86184@C02TD0UTHF1T.local> References: <20211021180236.37428-1-mark.rutland@arm.com> <20211021180236.37428-2-mark.rutland@arm.com> <87mtn1bazk.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87mtn1bazk.wl-maz@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 22, 2021 at 11:38:23AM +0100, Marc Zyngier wrote: > On Thu, 21 Oct 2021 19:02:22 +0100, > Mark Rutland wrote: > > > > As bcm6345_l1_irq_handle() is a chained irqchip handler, it will be > > invoked within the context of the root irqchip handler, which must have > > entered IRQ context already. > > > > When bcm6345_l1_irq_handle() calls arch/mips's do_IRQ() , this will nest > > another call to irq_enter(), and the resulting nested increment to > > `rcu_data.dynticks_nmi_nesting` will cause rcu_is_cpu_rrupt_from_idle() > > to fail to identify wakeups from idle, resulting in failure to preempt, > > and RCU stalls. > > > > Chained irqchip handlers must invoke IRQ handlers by way of thee core > > irqchip code, i.e. generic_handle_irq() or generic_handle_domain_irq() > > and should not call do_IRQ(), which is intended only for root irqchip > > handlers. > > > > Fix bcm6345_l1_irq_handle() by calling generic_handle_irq() directly. > > > > Fixes: c7c42ec2baa1de7a ("irqchips/bmips: Add bcm6345-l1 interrupt controller") > > Signed-off-by: Mark Rutland > > Cc: Marc Zyngier > > Cc: Thomas Bogendoerfer > > Cc: Thomas Gleixner > > --- > > drivers/irqchip/irq-bcm6345-l1.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/irqchip/irq-bcm6345-l1.c b/drivers/irqchip/irq-bcm6345-l1.c > > index e3483789f4df..1bd0621c4ce2 100644 > > --- a/drivers/irqchip/irq-bcm6345-l1.c > > +++ b/drivers/irqchip/irq-bcm6345-l1.c > > @@ -140,7 +140,7 @@ static void bcm6345_l1_irq_handle(struct irq_desc *desc) > > for_each_set_bit(hwirq, &pending, IRQS_PER_WORD) { > > irq = irq_linear_revmap(intc->domain, base + hwirq); > > if (irq) > > - do_IRQ(irq); > > + generic_handle_irq(irq); > > else > > spurious_interrupt(); > > } > > A marginally better fix would be to have: > > diff --git a/drivers/irqchip/irq-bcm6345-l1.c b/drivers/irqchip/irq-bcm6345-l1.c > index 1bd0621c4ce2..fd079215c17f 100644 > --- a/drivers/irqchip/irq-bcm6345-l1.c > +++ b/drivers/irqchip/irq-bcm6345-l1.c > @@ -132,16 +132,12 @@ static void bcm6345_l1_irq_handle(struct irq_desc *desc) > int base = idx * IRQS_PER_WORD; > unsigned long pending; > irq_hw_number_t hwirq; > - unsigned int irq; > > pending = __raw_readl(cpu->map_base + reg_status(intc, idx)); > pending &= __raw_readl(cpu->map_base + reg_enable(intc, idx)); > > for_each_set_bit(hwirq, &pending, IRQS_PER_WORD) { > - irq = irq_linear_revmap(intc->domain, base + hwirq); > - if (irq) > - generic_handle_irq(irq); > - else > + if (generic_handle_domain_irq(intc->domain, base + hwirq)) > spurious_interrupt(); > } > } > > but we can also tackle that separately if you'd rather keep the change > minimal. I'll add that to the series immediately after this patch, to keep this change minimal for backporting. Thanks, Mark.