From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757670Ab0IRTpY (ORCPT ); Sat, 18 Sep 2010 15:45:24 -0400 Received: from kroah.org ([198.145.64.141]:51600 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755862Ab0IRTB7 (ORCPT ); Sat, 18 Sep 2010 15:01:59 -0400 X-Mailbox-Line: From gregkh@clark.site Sat Sep 18 11:59:59 2010 Message-Id: <20100918185959.231710721@clark.site> User-Agent: quilt/0.48-11.2 Date: Sat, 18 Sep 2010 11:58:39 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Ingo Molnar , Peter Zijlstra , Greg KH , Thomas Gleixner , Peter Zijlstra , Mike Galbraith Subject: [075/123] sched: Use rcu in sched_get_rr_param() References: <20100918185724.290702750@clark.site> Content-Disposition: inline; filename=sched-use-rcu-in-sched_get_rr_param.patch In-Reply-To: <20100918190024.GA14388@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner commit 1a551ae715825bb2a2107a2dd68de024a1fa4e32 upstream read_lock(&tasklist_lock) does not protect sys_sched_get_rr_param() against a concurrent update of the policy or scheduler parameters as do_sched_scheduler() does not take the tasklist_lock. The access to task->sched_class->get_rr_interval is protected by task_rq_lock(task). Use rcu_read_lock() to protect find_task_by_vpid() and prevent the task struct from going away. Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra LKML-Reference: <20091209100706.862897167@linutronix.de> Signed-off-by: Ingo Molnar Signed-off-by: Mike Galbraith Signed-off-by: Greg Kroah-Hartman --- kernel/sched.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6924,7 +6924,7 @@ SYSCALL_DEFINE2(sched_rr_get_interval, p return -EINVAL; retval = -ESRCH; - read_lock(&tasklist_lock); + rcu_read_lock(); p = find_process_by_pid(pid); if (!p) goto out_unlock; @@ -6937,13 +6937,13 @@ SYSCALL_DEFINE2(sched_rr_get_interval, p time_slice = p->sched_class->get_rr_interval(rq, p); task_rq_unlock(rq, &flags); - read_unlock(&tasklist_lock); + rcu_read_unlock(); jiffies_to_timespec(time_slice, &t); retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; return retval; out_unlock: - read_unlock(&tasklist_lock); + rcu_read_unlock(); return retval; }