From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756121Ab0IRTKh (ORCPT ); Sat, 18 Sep 2010 15:10:37 -0400 Received: from kroah.org ([198.145.64.141]:51798 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754742Ab0IRTCT (ORCPT ); Sat, 18 Sep 2010 15:02:19 -0400 X-Mailbox-Line: From gregkh@clark.site Sat Sep 18 12:00:01 2010 Message-Id: <20100918190001.641957040@clark.site> User-Agent: quilt/0.48-11.2 Date: Sat, 18 Sep 2010 11:59:07 -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 , Mike Galbraith Subject: [103/123] sched: Remove unnecessary RCU exclusion References: <20100918185724.290702750@clark.site> Content-Disposition: inline; filename=sched-remove-unnecessary-rcu-exclusion.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: Peter Zijlstra commit fb58bac5c75bfff8bbf7d02071a10a62f32fe28b upstream As Nick pointed out, and realized by myself when doing: sched: Fix balance vs hotplug race the patch: sched: for_each_domain() vs RCU is wrong, sched_domains are freed after synchronize_sched(), which means disabling preemption is enough. Reported-by: Nick Piggin Signed-off-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar Signed-off-by: Mike Galbraith Signed-off-by: Greg Kroah-Hartman --- kernel/sched_fair.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1410,7 +1410,6 @@ select_task_rq_fair(struct rq *rq, struc new_cpu = prev_cpu; } - rcu_read_lock(); for_each_domain(cpu, tmp) { if (!(tmp->flags & SD_LOAD_BALANCE)) continue; @@ -1500,10 +1499,8 @@ select_task_rq_fair(struct rq *rq, struc } } - if (affine_sd && wake_affine(affine_sd, p, sync)) { - new_cpu = cpu; - goto out; - } + if (affine_sd && wake_affine(affine_sd, p, sync)) + return cpu; while (sd) { int load_idx = sd->forkexec_idx; @@ -1544,8 +1541,6 @@ select_task_rq_fair(struct rq *rq, struc /* while loop will break here if sd == NULL */ } -out: - rcu_read_unlock(); return new_cpu; } #endif /* CONFIG_SMP */