From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757683Ab0IRTqD (ORCPT ); Sat, 18 Sep 2010 15:46:03 -0400 Received: from kroah.org ([198.145.64.141]:51586 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755841Ab0IRTB6 (ORCPT ); Sat, 18 Sep 2010 15:01:58 -0400 X-Mailbox-Line: From gregkh@clark.site Sat Sep 18 11:59:59 2010 Message-Id: <20100918185959.052029509@clark.site> User-Agent: quilt/0.48-11.2 Date: Sat, 18 Sep 2010 11:58:37 -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: [073/123] sched: Use rcu in sys_sched_getscheduler/sys_sched_getparam() References: <20100918185724.290702750@clark.site> Content-Disposition: inline; filename=sched-use-rcu-in-sys_sched_getscheduler-sys_sched_getparam.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 5fe85be081edf0ac92d83f9c39e0ab5c1371eb82 upstream read_lock(&tasklist_lock) does not protect sys_sched_getscheduler and sys_sched_getparam() against a concurrent update of the policy or scheduler parameters as do_sched_setscheduler() does not take the tasklist_lock. The accessed integers can be retrieved w/o locking and are snapshots anyway. Using rcu_read_lock() to protect find_task_by_vpid() and prevent the task struct from going away is not changing the above situation. Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra LKML-Reference: <20091209100706.753790977@linutronix.de> Signed-off-by: Ingo Molnar Signed-off-by: Mike Galbraith Signed-off-by: Greg Kroah-Hartman --- kernel/sched.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6505,7 +6505,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_ return -EINVAL; retval = -ESRCH; - read_lock(&tasklist_lock); + rcu_read_lock(); p = find_process_by_pid(pid); if (p) { retval = security_task_getscheduler(p); @@ -6513,7 +6513,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_ retval = p->policy | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); } - read_unlock(&tasklist_lock); + rcu_read_unlock(); return retval; } @@ -6531,7 +6531,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, p if (!param || pid < 0) return -EINVAL; - read_lock(&tasklist_lock); + rcu_read_lock(); p = find_process_by_pid(pid); retval = -ESRCH; if (!p) @@ -6542,7 +6542,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, p goto out_unlock; lp.sched_priority = p->rt_priority; - read_unlock(&tasklist_lock); + rcu_read_unlock(); /* * This one might sleep, we cannot do it with a spinlock held ... @@ -6552,7 +6552,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, p return retval; out_unlock: - read_unlock(&tasklist_lock); + rcu_read_unlock(); return retval; }