Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758010AbcDELNL (ORCPT ); Tue, 5 Apr 2016 07:13:11 -0400 Received: from www.linutronix.de ([62.245.132.108]:37572 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755228AbcDELNI (ORCPT ); Tue, 5 Apr 2016 07:13:08 -0400 Subject: Re: [PREEMPT-RT] [PATCH] s390/cpum_sf: Remove superfluous SMP function call To: Heiko Carstens , Anna-Maria Gleixner References: <1459765640-13599-1-git-send-email-anna-maria@linutronix.de> <20160405104912.GC3937@osiris> Cc: Martin Schwidefsky , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, rt@linutronix.de From: Sebastian Andrzej Siewior Message-ID: <57039DC2.6090907@linutronix.de> Date: Tue, 5 Apr 2016 13:13:06 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Icedove/38.7.0 MIME-Version: 1.0 In-Reply-To: <20160405104912.GC3937@osiris> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit 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 Content-Length: 892 Lines: 27 On 04/05/2016 12:49 PM, Heiko Carstens wrote: >> --- a/arch/s390/kernel/perf_cpum_sf.c >> +++ b/arch/s390/kernel/perf_cpum_sf.c >> @@ -1510,7 +1510,6 @@ static void cpumf_measurement_alert(stru >> static int cpumf_pmu_notifier(struct notifier_block *self, >> unsigned long action, void *hcpu) >> { >> - unsigned int cpu = (long) hcpu; >> int flags; >> >> /* Ignore the notification if no events are scheduled on the PMU. >> @@ -1523,11 +1522,15 @@ static int cpumf_pmu_notifier(struct not >> case CPU_ONLINE: >> case CPU_DOWN_FAILED: >> flags = PMC_INIT; >> - smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1); >> + local_irq_disable(); >> + setup_pmc_cpu(&flags); >> + local_irq_enable(); >> break; > > ...but at least the CPU_DOWN_FAILED callback will not necessarily be called > on the cpu that couldn't be brought offline. I don't follow. Sebastian