From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935076AbaKNBiR (ORCPT ); Thu, 13 Nov 2014 20:38:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33178 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934808AbaKNBiN (ORCPT ); Thu, 13 Nov 2014 20:38:13 -0500 Date: Fri, 14 Nov 2014 02:38:20 +0100 From: Oleg Nesterov To: Andrew Morton Cc: Aaron Tomlin , "Eric W. Biederman" , Rik van Riel , Sterling Alexander , linux-kernel@vger.kernel.org Subject: [PATCH 3/5] exit: wait: drop tasklist_lock before psig->c* accounting Message-ID: <20141114013820.GA5126@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141114013750.GA4697@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 wait_task_zombie() no longer needs tasklist_lock to accumulate the psig->c* counters, we can drop it right after cmpxchg(exit_state). Signed-off-by: Oleg Nesterov --- kernel/exit.c | 10 ++++------ 1 files changed, 4 insertions(+), 6 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 40d53de..e0914eb 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1003,6 +1003,10 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) EXIT_TRACE : EXIT_DEAD; if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) return 0; + /* + * We own this thread, nobody else can reap it. + */ + read_unlock(&tasklist_lock); /* * Check thread_group_leader() to exclude the traced sub-threads. @@ -1062,12 +1066,6 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) spin_unlock_irq(¤t->sighand->siglock); } - /* - * Now we are sure this task is interesting, and no other - * thread can reap it because we its state == DEAD/TRACE. - */ - read_unlock(&tasklist_lock); - retval = wo->wo_rusage ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; status = (p->signal->flags & SIGNAL_GROUP_EXIT) -- 1.5.5.1