Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752145Ab3INEmJ (ORCPT ); Sat, 14 Sep 2013 00:42:09 -0400 Received: from mail-pd0-f172.google.com ([209.85.192.172]:36754 "EHLO mail-pd0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751632Ab3INEmH (ORCPT ); Sat, 14 Sep 2013 00:42:07 -0400 Date: Sat, 14 Sep 2013 12:41:36 +0800 From: Wang YanQing To: Jiang Liu Cc: Andrew Morton , Shaohua Li , Jiang Liu , Ingo Molnar , Peter Zijlstra , Steven Rostedt , Jiri Kosina , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH v2 01/25] Revert smp: Fix SMP function call empty cpu mask race Message-ID: <20130914044136.GA2944@udknight> Mail-Followup-To: Wang YanQing , Jiang Liu , Andrew Morton , Shaohua Li , Jiang Liu , Ingo Molnar , Peter Zijlstra , Steven Rostedt , Jiri Kosina , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org References: <1378915649-16395-1-git-send-email-liuj97@gmail.com> <1378915649-16395-2-git-send-email-liuj97@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1378915649-16395-2-git-send-email-liuj97@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3723 Lines: 101 On Thu, Sep 12, 2013 at 12:07:05AM +0800, Jiang Liu wrote: > From: Jiang Liu > > Commit f44310b98ddb7 "smp: Fix SMP function call empty cpu mask race" > introduced field call_function_data->cpumask_ipi to resolve a race > condition in smp_call_function_many(). > > Later commit 9a46ad6d6df3 "smp: make smp_call_function_many() use logic > similar to smp_call_function_single()" fixed the same issue in another > way when optimizing smp_call_function_many(), which then obsoletes > changes introduced by commit f44310b98ddb7. So revert it. > > Signed-off-by: Jiang Liu > Acked-by: Wang YanQing > Cc: Jiang Liu > --- > kernel/smp.c | 16 ++-------------- > 1 file changed, 2 insertions(+), 14 deletions(-) > > diff --git a/kernel/smp.c b/kernel/smp.c > index fe9f773..a034712 100644 > --- a/kernel/smp.c > +++ b/kernel/smp.c > @@ -23,7 +23,6 @@ enum { > struct call_function_data { > struct call_single_data __percpu *csd; > cpumask_var_t cpumask; > - cpumask_var_t cpumask_ipi; > }; > > static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data); > @@ -47,9 +46,6 @@ hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) > if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, > cpu_to_node(cpu))) > return notifier_from_errno(-ENOMEM); > - if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL, > - cpu_to_node(cpu))) > - return notifier_from_errno(-ENOMEM); > cfd->csd = alloc_percpu(struct call_single_data); > if (!cfd->csd) { > free_cpumask_var(cfd->cpumask); > @@ -64,7 +60,6 @@ hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) > case CPU_DEAD: > case CPU_DEAD_FROZEN: > free_cpumask_var(cfd->cpumask); > - free_cpumask_var(cfd->cpumask_ipi); > free_percpu(cfd->csd); > break; > #endif > @@ -255,9 +250,9 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, > csd = &__get_cpu_var(csd_data); > > csd_lock(csd); > - > csd->func = func; > csd->info = info; > + > generic_exec_single(cpu, csd, wait); > } else { > err = -ENXIO; /* CPU not online */ > @@ -410,13 +405,6 @@ void smp_call_function_many(const struct cpumask *mask, > if (unlikely(!cpumask_weight(cfd->cpumask))) > return; > > - /* > - * After we put an entry into the list, cfd->cpumask may be cleared > - * again when another CPU sends another IPI for a SMP function call, so > - * cfd->cpumask will be zero. > - */ > - cpumask_copy(cfd->cpumask_ipi, cfd->cpumask); > - > for_each_cpu(cpu, cfd->cpumask) { > struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu); > struct call_single_queue *dst = > @@ -433,7 +421,7 @@ void smp_call_function_many(const struct cpumask *mask, > } > > /* Send a message to all CPUs in the map */ > - arch_send_call_function_ipi_mask(cfd->cpumask_ipi); > + arch_send_call_function_ipi_mask(cfd->cpumask); > > if (wait) { > for_each_cpu(cpu, cfd->cpumask) { > -- > 1.8.1.2 Hi Liu and all Commit 60c323699bb308404dcb60e8808531e02651578a (kernel/smp.c: free related resources when failure occurs in hotplug_cfd()) is a fix patch for commit you revert, and it had been merged into mainline. So could you ajust your patch to revert it together? I don't think we need a separate patch to revert 60c323699bb308404dcb60e8808531e02651578a, because your patch haven't be merged. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/