From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752598AbaIUTgl (ORCPT ); Sun, 21 Sep 2014 15:36:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56825 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752222AbaIUTgi (ORCPT ); Sun, 21 Sep 2014 15:36:38 -0400 Date: Sun, 21 Sep 2014 21:33:38 +0200 From: Oleg Nesterov To: Ingo Molnar , Peter Zijlstra Cc: Kirill Tkhai , Mike Galbraith , linux-kernel@vger.kernel.org Subject: [PATCH 2/3] sched: normalize_rt_tasks: don't use _irqsave for tasklist_lock, use task_rq_lock() Message-ID: <20140921193338.GA28621@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140921193316.GA28596@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 1. read_lock(tasklist_lock) does not need to disable irqs. 2. ->mm != NULL is the common mistake, use PF_KTHREAD. 3. The second ->mm check can be simply removed. 4. task_rq_lock() looks better than raw_spin_lock(&p->pi_lock) + __task_rq_lock(). Signed-off-by: Oleg Nesterov --- kernel/sched/core.c | 16 ++++++---------- 1 files changed, 6 insertions(+), 10 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8a6506f..eee12b3 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7137,12 +7137,12 @@ void normalize_rt_tasks(void) unsigned long flags; struct rq *rq; - read_lock_irqsave(&tasklist_lock, flags); + read_lock(&tasklist_lock); for_each_process_thread(g, p) { /* * Only normalize user tasks: */ - if (!p->mm) + if (p->flags & PF_KTHREAD) continue; p->se.exec_start = 0; @@ -7157,20 +7157,16 @@ void normalize_rt_tasks(void) * Renice negative nice level userspace * tasks back to 0: */ - if (task_nice(p) < 0 && p->mm) + if (task_nice(p) < 0) set_user_nice(p, 0); continue; } - raw_spin_lock(&p->pi_lock); - rq = __task_rq_lock(p); - + rq = task_rq_lock(p, &flags); normalize_task(rq, p); - - __task_rq_unlock(rq); - raw_spin_unlock(&p->pi_lock); + task_rq_unlock(rq, p, &flags); } - read_unlock_irqrestore(&tasklist_lock, flags); + read_unlock(&tasklist_lock); } #endif /* CONFIG_MAGIC_SYSRQ */ -- 1.5.5.1