From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759576AbZFOInp (ORCPT ); Mon, 15 Jun 2009 04:43:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759521AbZFOIna (ORCPT ); Mon, 15 Jun 2009 04:43:30 -0400 Received: from mx2.redhat.com ([66.187.237.31]:54148 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759600AbZFOIn3 (ORCPT ); Mon, 15 Jun 2009 04:43:29 -0400 Date: Mon, 15 Jun 2009 10:36:59 +0200 From: Stanislaw Gruszka To: Thomas Gleixner Cc: "linux-kernel@vger.kernel.org" , Oleg Nesterov , Peter Zijlstra , Ingo Molnar Subject: [PATCH 2/2] posix-cpu-timers: remove tasklist_lock where we can Message-ID: <20090615103659.45c39df1@dhcp-lab-109.englab.brq.redhat.com> Organization: RedHat Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org tasklist_lock is not needed to protect find_task_by_vpid() nor same_thread_group() and if we replace thread_group_leader() by has_group_leader_pid() we can just use RCU lock to protect some process timers/clocks checks. Signed-off-by: Stanislaw Gruszka --- kernel/posix-cpu-timers.c | 12 ++++++------ 1 files changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index bece7c0..029b442 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -37,13 +37,13 @@ static int check_clock(const clockid_t which_clock) if (pid == 0) return 0; - read_lock(&tasklist_lock); + rcu_read_lock(); p = find_task_by_vpid(pid); if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ? - same_thread_group(p, current) : thread_group_leader(p))) { + same_thread_group(p, current) : has_group_leader_pid(p))) { error = -EINVAL; } - read_unlock(&tasklist_lock); + rcu_read_unlock(); return error; } @@ -398,7 +398,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) new_timer->it.cpu.incr.sched = 0; new_timer->it.cpu.expires.sched = 0; - read_lock(&tasklist_lock); + rcu_read_lock(); if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) { if (pid == 0) { p = current; @@ -412,7 +412,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) p = current->group_leader; } else { p = find_task_by_vpid(pid); - if (p && !thread_group_leader(p)) + if (p && !has_group_leader_pid(p)) p = NULL; } } @@ -422,7 +422,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) } else { ret = -EINVAL; } - read_unlock(&tasklist_lock); + rcu_read_unlock(); return ret; } -- 1.5.5.6