From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754590AbaDOPmD (ORCPT ); Tue, 15 Apr 2014 11:42:03 -0400 Received: from mailout1.w1.samsung.com ([210.118.77.11]:15769 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750902AbaDOPl6 (ORCPT ); Tue, 15 Apr 2014 11:41:58 -0400 MIME-version: 1.0 Content-type: text/plain; charset=UTF-8 X-AuditID: cbfec7f5-b7fc96d000004885-15-534d5343cedd Content-transfer-encoding: 8BIT Message-id: <1397576515.752.5.camel@AMDC1943> Subject: Re: [PATCH 1/3] clocksource: exynos_mct: Fix stall after CPU hotplugging From: Krzysztof Kozlowski To: Thomas Gleixner Cc: Daniel Lezcano , Kukjin Kim , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, Kyungmin Park , Marek Szyprowski , Bartlomiej Zolnierkiewicz , Tomasz Figa , stable@vger.kernel.org Date: Tue, 15 Apr 2014 17:41:55 +0200 In-reply-to: References: <1396011962-4467-1-git-send-email-k.kozlowski@samsung.com> <1397554445.29169.21.camel@AMDC1943> <534D25DC.4050400@linaro.org> <1397566023.29169.31.camel@AMDC1943> X-Mailer: Evolution 3.8.4-0ubuntu1 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrHLMWRmVeSWpSXmKPExsVy+t/xK7rOwb7BBreX6llsnLGe1WLeZ1mL 3gVX2SzONr1ht9j0+BqrxeVdc9gsZpzfx2Sx9shddosFGx8xWqyf8ZrFYvOmqcwO3B53ru1h 83h37hy7x+Yl9R59W1YxenzeJBfAGsVlk5Kak1mWWqRvl8CVceXUZPaCPVIVp9pfsDcwvhfp YuTkkBAwkeh9epYNwhaTuHBvPZgtJLCUUeJfuzOIzSsgKPFj8j2WLkYODmYBeYkjl7JBwswC 6hKT5i1i7mLkAir/zCjR1bucGaSGV0BXYvaCIpAaYYFgib+nN7KD2GwCxhKbly8BGy8ioCGx 8dItsF5mgV5miZdXTzCCJFgEVCWWnnwOVsQp4CUx+dt8RogFnxgl5rduhTpUSeLcujWMExgF ZiG5bxbCfbOQ3LeAkXkVo2hqaXJBcVJ6rpFecWJucWleul5yfu4mRkgcfN3BuPSY1SFGAQ5G JR7eCe+8g4VYE8uKK3MPMUpwMCuJ8H7k9g0W4k1JrKxKLcqPLyrNSS0+xMjEwSnVwGjy61rE Kimlo2lrPxm6WvBI1R9+8H3zyk+Vjx6y+Mh+8bx/8dy8hAKFtAWtlydEvjsYEVD6XcSVMTzR bZGWx5pLJiV/3I6XTZ/7Vy/o7+SDP0KFJm1WP9J9fPoM0Ufat3x3Wan7dSlEXvS7ZbonouOo 5BrZK7HzNrVMSfxjJpW6fuq/zad/teUosRRnJBpqMRcVJwIAHhF17mECAAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On wto, 2014-04-15 at 17:20 +0200, Thomas Gleixner wrote: > On Tue, 15 Apr 2014, Krzysztof Kozlowski wrote: > > > On wto, 2014-04-15 at 14:28 +0200, Daniel Lezcano wrote: > > > On 04/15/2014 11:34 AM, Krzysztof Kozlowski wrote: > > > > On pią, 2014-03-28 at 14:06 +0100, Krzysztof Kozlowski wrote: > > > >> Fix stall after hotplugging CPU1. Affected are SoCs where Multi Core Timer > > > >> interrupts are shared (SPI), e.g. Exynos 4210. The stall was a result of > > > >> starting the CPU1 local timer not in L1 timer but in L0 (which is used > > > >> by CPU0). > > > > > > > > Hi, > > > > > > > > Do you have any comments on these 3 patches? They fix the CPU stall on > > > > Exynos4210 and also on Exynos3250 (Chanwoo Choi sent patches for it > > > > recently). > > > > > > You describe this issue as impacting different SoC not only the exynos, > > > right ? > > > > > > Do you know what other SoCs are impacted by this ? > > > > No, affected are only Exynos SoC-s. It was confirmed on Exynos4210 > > (Trats board) and Exynos3250 (new SoC, patches for it were recently > > posted by Chanwoo). > > > > Other Exynos SoC-s where MCT local timers use shared interrupts (SPI) > > can also be affected. Candidates are Exynos 5250 and 5420 but I haven't > > tested them. > > > > > I guess this issue is not reproducible just with the line below, we need > > > a timer to expire right at the moment CPU1 is hotplugged, right ? > > > > Right. The timer must fire in short time between enabling local timer > > for CPU1 and setting the affinity for IRQ. > > Why do you set the affinity in the CPU_ONLINE hotplug callback and not > right away when the interrupt is requested? Hi, I think the problem in such code is in GIC. The gic_set_affinity() uses cpu_online_mask: unsigned int cpu = cpumask_any_and(mask_val, cpu_online_mask); In that time this CPU is not present in that mask so -EINVAL would be returned. The stall occurred also on 3.10 where the IRQ affinity is set just after setup_irq(): if (cpu == 0) { mct_tick0_event_irq.dev_id = mevt; evt->irq = mct_irqs[MCT_L0_IRQ]; setup_irq(evt->irq, &mct_tick0_event_irq); } else { mct_tick1_event_irq.dev_id = mevt; evt->irq = mct_irqs[MCT_L1_IRQ]; setup_irq(evt->irq, &mct_tick1_event_irq); irq_set_affinity(evt->irq, cpumask_of(1)); } Best regards, Krzysztof > Thanks, > > tglx > > > Index: linux-2.6/drivers/clocksource/exynos_mct.c > =================================================================== > --- linux-2.6.orig/drivers/clocksource/exynos_mct.c > +++ linux-2.6/drivers/clocksource/exynos_mct.c > @@ -430,6 +430,7 @@ static int exynos4_local_timer_setup(str > evt->irq); > return -EIO; > } > + irq_set_affinity(mct_irqs[MCT_L0_IRQ + cpu], cpumask_of(cpu)); > } else { > enable_percpu_irq(mct_irqs[MCT_L0_IRQ], 0); > } > @@ -461,12 +462,6 @@ static int exynos4_mct_cpu_notify(struct > mevt = this_cpu_ptr(&percpu_mct_tick); > exynos4_local_timer_setup(&mevt->evt); > break; > - case CPU_ONLINE: > - cpu = (unsigned long)hcpu; > - if (mct_int_type == MCT_INT_SPI) > - irq_set_affinity(mct_irqs[MCT_L0_IRQ + cpu], > - cpumask_of(cpu)); > - break; > case CPU_DYING: > mevt = this_cpu_ptr(&percpu_mct_tick); > exynos4_local_timer_stop(&mevt->evt); > > >