From patchwork Tue Dec 4 08:55:23 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Srivatsa S. Bhat" X-Patchwork-Id: 1836921 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id 280683FC71 for ; Tue, 4 Dec 2012 08:59:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753244Ab2LDI6t (ORCPT ); Tue, 4 Dec 2012 03:58:49 -0500 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:36722 "EHLO e23smtp07.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752910Ab2LDI4w (ORCPT ); Tue, 4 Dec 2012 03:56:52 -0500 Received: from /spool/local by e23smtp07.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 4 Dec 2012 18:52:09 +1000 Received: from d23dlp03.au.ibm.com (202.81.31.214) by e23smtp07.au.ibm.com (202.81.31.204) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Tue, 4 Dec 2012 18:52:07 +1000 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [9.190.235.21]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id 8A9E63578052; Tue, 4 Dec 2012 19:56:47 +1100 (EST) Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id qB48ulRh58261650; Tue, 4 Dec 2012 19:56:47 +1100 Received: from d23av04.au.ibm.com (loopback [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id qB48uidA019189; Tue, 4 Dec 2012 19:56:47 +1100 Received: from srivatsabhat.in.ibm.com (srivatsabhat.in.ibm.com [9.124.35.159]) by d23av04.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id qB48ueHi019091; Tue, 4 Dec 2012 19:56:41 +1100 From: "Srivatsa S. Bhat" Subject: [RFC PATCH 06/10] yield_to(), cpu-hotplug: Prevent offlining of other CPUs properly To: tglx@linutronix.de, peterz@infradead.org, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, vincent.guittot@linaro.org Cc: sbw@mit.edu, tj@kernel.org, amit.kucheria@linaro.org, rostedt@goodmis.org, rjw@sisk.pl, srivatsa.bhat@linux.vnet.ibm.com, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 04 Dec 2012 14:25:23 +0530 Message-ID: <20121204085514.25919.74050.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20121204085149.25919.29920.stgit@srivatsabhat.in.ibm.com> References: <20121204085149.25919.29920.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12120408-0260-0000-0000-0000023FF6B0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org With stop_machine() gone from the CPU offline path, we can't depend on local_irq_save() to prevent CPUs from going offline from under us. Use the get/put_online_cpus_stable_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context. And use the stable online mask while interacting with other CPUs. Signed-off-by: Srivatsa S. Bhat --- kernel/sched/core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) -- 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/sched/core.c b/kernel/sched/core.c index c1a5d93..d0b159b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4312,6 +4312,7 @@ bool __sched yield_to(struct task_struct *p, bool preempt) unsigned long flags; bool yielded = 0; + get_online_cpus_stable_atomic(); local_irq_save(flags); rq = this_rq(); @@ -4339,13 +4340,14 @@ again: * Make p's CPU reschedule; pick_next_entity takes care of * fairness. */ - if (preempt && rq != p_rq) + if (preempt && rq != p_rq && cpu_online_stable(task_cpu(p))) resched_task(p_rq->curr); } out: double_rq_unlock(rq, p_rq); local_irq_restore(flags); + put_online_cpus_stable_atomic(); if (yielded) schedule();