From patchwork Tue Jan 22 07:35:17 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Srivatsa S. Bhat" X-Patchwork-Id: 2016831 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id B9E79DF2EB for ; Tue, 22 Jan 2013 07:53:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754366Ab3AVHh3 (ORCPT ); Tue, 22 Jan 2013 02:37:29 -0500 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:40960 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754041Ab3AVHhZ (ORCPT ); Tue, 22 Jan 2013 02:37:25 -0500 Received: from /spool/local by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Bhat" Subject: [PATCH v5 10/45] smp, cpu hotplug: Fix on_each_cpu_*() to prevent CPU offline properly To: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org Cc: rostedt@goodmis.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, rjw@sisk.pl, sbw@mit.edu, fweisbec@gmail.com, linux@arm.linux.org.uk, nikunj@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 22 Jan 2013 13:05:17 +0530 Message-ID: <20130122073515.13822.80220.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13012207-6102-0000-0000-000002E62A98 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Once stop_machine() is gone from the CPU offline path, we won't be able to depend on preempt_disable() to prevent CPUs from going offline from under us. Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context. Signed-off-by: Srivatsa S. Bhat --- kernel/smp.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/kernel/smp.c b/kernel/smp.c index f421bcc..d870bfe 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -688,12 +688,12 @@ int on_each_cpu(void (*func) (void *info), void *info, int wait) unsigned long flags; int ret = 0; - preempt_disable(); + get_online_cpus_atomic(); ret = smp_call_function(func, info, wait); local_irq_save(flags); func(info); local_irq_restore(flags); - preempt_enable(); + put_online_cpus_atomic(); return ret; } EXPORT_SYMBOL(on_each_cpu); @@ -715,7 +715,11 @@ EXPORT_SYMBOL(on_each_cpu); void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, void *info, bool wait) { - int cpu = get_cpu(); + int cpu; + + get_online_cpus_atomic(); + + cpu = smp_processor_id(); smp_call_function_many(mask, func, info, wait); if (cpumask_test_cpu(cpu, mask)) { @@ -723,7 +727,7 @@ void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, func(info); local_irq_enable(); } - put_cpu(); + put_online_cpus_atomic(); } EXPORT_SYMBOL(on_each_cpu_mask); @@ -748,8 +752,9 @@ EXPORT_SYMBOL(on_each_cpu_mask); * The function might sleep if the GFP flags indicates a non * atomic allocation is allowed. * - * Preemption is disabled to protect against CPUs going offline but not online. - * CPUs going online during the call will not be seen or sent an IPI. + * We use get/put_online_cpus_atomic() to prevent CPUs from going + * offline in-between our operation. CPUs coming online during the + * call will not be seen or sent an IPI. * * You must not call this function with disabled interrupts or * from a hardware interrupt handler or from a bottom half handler. @@ -764,26 +769,26 @@ void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), might_sleep_if(gfp_flags & __GFP_WAIT); if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) { - preempt_disable(); + get_online_cpus_atomic(); for_each_online_cpu(cpu) if (cond_func(cpu, info)) cpumask_set_cpu(cpu, cpus); on_each_cpu_mask(cpus, func, info, wait); - preempt_enable(); + put_online_cpus_atomic(); free_cpumask_var(cpus); } else { /* * No free cpumask, bother. No matter, we'll * just have to IPI them one by one. */ - preempt_disable(); + get_online_cpus_atomic(); for_each_online_cpu(cpu) if (cond_func(cpu, info)) { ret = smp_call_function_single(cpu, func, info, wait); WARN_ON_ONCE(!ret); } - preempt_enable(); + put_online_cpus_atomic(); } } EXPORT_SYMBOL(on_each_cpu_cond);