From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755402AbcIEJQb (ORCPT ); Mon, 5 Sep 2016 05:16:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51812 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754662AbcIEJQ2 (ORCPT ); Mon, 5 Sep 2016 05:16:28 -0400 From: Stanislaw Gruszka To: linux-kernel@vger.kernel.org Cc: Giovanni Gherdovich , Linus Torvalds , Mel Gorman , Mike Galbraith , Paolo Bonzini , Peter Zijlstra , Rik van Riel , Thomas Gleixner , Wanpeng Li , Ingo Molnar , Stanislaw Gruszka Subject: [PATCH v2 1/2] sched/cputime: Use only pi_lock to protect sum_exec_runtime read Date: Mon, 5 Sep 2016 11:13:01 +0200 Message-Id: <1473066782-19372-2-git-send-email-sgruszka@redhat.com> In-Reply-To: <1473066782-19372-1-git-send-email-sgruszka@redhat.com> References: <1473066782-19372-1-git-send-email-sgruszka@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Mon, 05 Sep 2016 09:16:27 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently we protect 64bit sum_exec_runtime read on 32bit cpus using task_rq_lock() which internally takes t->pi_lock and rq->lock. Taking rq->lock is not needed in this case. Signed-off-by: Stanislaw Gruszka --- kernel/sched/cputime.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index b93c72d..5535774 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -315,12 +315,11 @@ static inline u64 read_sum_exec_runtime(struct task_struct *t) static u64 read_sum_exec_runtime(struct task_struct *t) { u64 ns; - struct rq_flags rf; - struct rq *rq; + unsigned long flags; - rq = task_rq_lock(t, &rf); + raw_spin_lock_irqsave(&t->pi_lock, flags); ns = t->se.sum_exec_runtime; - task_rq_unlock(rq, t, &rf); + raw_spin_unlock_irqrestore(&t->pi_lock, flags); return ns; } -- 1.8.3.1