From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Wed, 14 Feb 2018 12:40:17 +0100 (CET) Received: from foss.arm.com ([217.140.101.70]:45436 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S23991172AbeBNLkGbuR0Y (ORCPT ); Wed, 14 Feb 2018 12:40:06 +0100 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3450A80D; Wed, 14 Feb 2018 03:39:59 -0800 (PST) Received: from [10.1.207.62] (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 23AC53F487; Wed, 14 Feb 2018 03:39:57 -0800 (PST) Subject: Re: [PATCH] irqchip: mips-gic: Avoid spuriously handling masked interrupts To: Matt Redfearn , Thomas Gleixner Cc: linux-mips@linux-mips.org, Ralf Baechle , Jason Cooper , linux-kernel@vger.kernel.org References: <1517849136-29508-1-git-send-email-matt.redfearn@mips.com> <5d6348d6-a87f-d3b7-b758-9a2003d9c50e@arm.com> From: Marc Zyngier Organization: ARM Ltd Message-ID: <892584b8-c61e-e9da-1bd3-5187b8194d84@arm.com> Date: Wed, 14 Feb 2018 11:39:56 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 62536 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: marc.zyngier@arm.com Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On 14/02/18 11:22, Matt Redfearn wrote: > > > On 07/02/18 10:41, Marc Zyngier wrote: >> On 07/02/18 09:44, Matt Redfearn wrote: >>> Hi Marc, >>> >>> On 07/02/18 09:41, Marc Zyngier wrote: >>>> On 05/02/18 16:45, Matt Redfearn wrote: >>>>> Commit 7778c4b27cbe ("irqchip: mips-gic: Use pcpu_masks to avoid reading >>>>> GIC_SH_MASK*") removed the read of the hardware mask register when >>>>> handling shared interrupts, instead using the driver's shadow pcpu_masks >>>>> entry as the effective mask. Unfortunately this did not take account of >>>>> the write to pcpu_masks during gic_shared_irq_domain_map, which >>>>> effectively unmasks the interrupt early. If an interrupt is asserted, >>>>> gic_handle_shared_int decodes and processes the interrupt even though it >>>>> has not yet been unmasked via gic_unmask_irq, which also sets the >>>>> appropriate bit in pcpu_masks. >>>>> >>>>> On the MIPS Boston board, when a console command line of >>>>> "console=ttyS0,115200n8r" is passed, the modem status IRQ is enabled in >>>>> the UART, which is immediately raised to the GIC. The interrupt has been >>>>> mapped, but no handler has yet been registered, nor is it expected to be >>>>> unmasked. However, the write to pcpu_masks in gic_shared_irq_domain_map >>>>> has effectively unmasked it, resulting in endless reports of: >>>>> >>>>> [ 5.058454] irq 13, desc: ffffffff80a7ad80, depth: 1, count: 0, unhandled: 0 >>>>> [ 5.062057] ->handle_irq(): ffffffff801b1838, >>>>> [ 5.062175] handle_bad_irq+0x0/0x2c0 >>>>> >>>>> Where IRQ 13 is the UART interrupt. >>>>> >>>>> To fix this, just remove the write to pcpu_masks in >>>>> gic_shared_irq_domain_map. The existing write in gic_unmask_irq is the >>>>> correct place for what is now the effective unmasking. >>>>> >>>>> Fixes: 7778c4b27cbe ("irqchip: mips-gic: Use pcpu_masks to avoid reading GIC_SH_MASK*") >>>>> Signed-off-by: Matt Redfearn >>>>> Reviewed-by: Paul Burton >>>>> >>>>> --- >>>>> >>>>> drivers/irqchip/irq-mips-gic.c | 2 -- >>>>> 1 file changed, 2 deletions(-) >>>>> >>>>> diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c >>>>> index b2cfc6d66d74..2c3684ba46e5 100644 >>>>> --- a/drivers/irqchip/irq-mips-gic.c >>>>> +++ b/drivers/irqchip/irq-mips-gic.c >>>>> @@ -429,8 +429,6 @@ static int gic_shared_irq_domain_map(struct irq_domain *d, unsigned int virq, >>>>> spin_lock_irqsave(&gic_lock, flags); >>>>> write_gic_map_pin(intr, GIC_MAP_PIN_MAP_TO_PIN | shared_cpu_pin); >>>>> write_gic_map_vp(intr, BIT(mips_cm_vp_id(cpu))); >>>>> - gic_clear_pcpu_masks(intr); >>>>> - set_bit(intr, per_cpu_ptr(pcpu_masks, cpu)); >>>>> irq_data_update_effective_affinity(data, cpumask_of(cpu)); >>>>> spin_unlock_irqrestore(&gic_lock, flags); >>>>> >>>>> >>>> >>>> Does this need to be Cc to stable (since it fixes something that was >>>> merged in 4.14)? >>> >>> Sorry, missed stable off the CC list. Yes, it does indeed need to be >>> backported. Should I resubmit? >> No need, I'll add that to the patch. > > Hi Marc, > Not seen this turn up in tip, just wanted to check you're going to pick > it up? I haven't sent anything to tglx just yet, might do it tomorrow once I get a chance. Thanks, M. -- Jazz is not dead. It just smells funny...