From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757824AbZLNQc4 (ORCPT ); Mon, 14 Dec 2009 11:32:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755274AbZLNQcy (ORCPT ); Mon, 14 Dec 2009 11:32:54 -0500 Received: from hera.kernel.org ([140.211.167.34]:34104 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755103AbZLNQcx (ORCPT ); Mon, 14 Dec 2009 11:32:53 -0500 Date: Mon, 14 Dec 2009 16:31:03 GMT From: tip-bot for Thomas Gleixner Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20091209100706.753790977@linutronix.de> References: <20091209100706.753790977@linutronix.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] sched: Use rcu in sys_sched_getscheduler/sys_sched_getparam() Message-ID: Git-Commit-ID: 5fe85be081edf0ac92d83f9c39e0ab5c1371eb82 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 5fe85be081edf0ac92d83f9c39e0ab5c1371eb82 Gitweb: http://git.kernel.org/tip/5fe85be081edf0ac92d83f9c39e0ab5c1371eb82 Author: Thomas Gleixner AuthorDate: Wed, 9 Dec 2009 10:14:58 +0000 Committer: Ingo Molnar CommitDate: Mon, 14 Dec 2009 17:11:34 +0100 sched: Use rcu in sys_sched_getscheduler/sys_sched_getparam() 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 --- kernel/sched.c | 10 +++++----- 1 files changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 258c73c..1782bee 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6458,7 +6458,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_t, 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); @@ -6466,7 +6466,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) retval = p->policy | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); } - read_unlock(&tasklist_lock); + rcu_read_unlock(); return retval; } @@ -6484,7 +6484,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) if (!param || pid < 0) return -EINVAL; - read_lock(&tasklist_lock); + rcu_read_lock(); p = find_process_by_pid(pid); retval = -ESRCH; if (!p) @@ -6495,7 +6495,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) 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 ... @@ -6505,7 +6505,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) return retval; out_unlock: - read_unlock(&tasklist_lock); + rcu_read_unlock(); return retval; }