From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753904AbbAEKiu (ORCPT ); Mon, 5 Jan 2015 05:38:50 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:36823 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753646AbbAEKhi (ORCPT ); Mon, 5 Jan 2015 05:37:38 -0500 Message-Id: <20150105103554.361872747@infradead.org> User-Agent: quilt/0.61-1 Date: Mon, 05 Jan 2015 11:18:10 +0100 From: Peter Zijlstra To: mingo@kernel.org, umgwanakikbuti@gmail.com Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, "Peter Zijlstra" Subject: [RFC][PATCH 1/3] sched: Validate rq_clock*() serialization References: <20150105101809.860964488@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-sched-rq_clock-locking.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org rq->clock{,_task} are serialized by rq->lock, verify this. One immediate fail is the usage in scale_rt_capability, so 'annotate' that for now, there's more 'funny' there. Maybe change rq->lock into a raw_seqlock_t? (Only 32bit is affected) Signed-off-by: Peter Zijlstra (Intel) --- kernel/sched/fair.c | 2 +- kernel/sched/sched.h | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5945,8 +5945,8 @@ static unsigned long scale_rt_capacity(i */ age_stamp = ACCESS_ONCE(rq->age_stamp); avg = ACCESS_ONCE(rq->rt_avg); + delta = __rq_clock_broken(rq) - age_stamp; - delta = rq_clock(rq) - age_stamp; if (unlikely(delta < 0)) delta = 0; --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -687,13 +687,20 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct rq #define cpu_curr(cpu) (cpu_rq(cpu)->curr) #define raw_rq() raw_cpu_ptr(&runqueues) +static inline u64 __rq_clock_broken(struct rq *rq) +{ + return ACCESS_ONCE(rq->clock); +} + static inline u64 rq_clock(struct rq *rq) { + lockdep_assert_held(&rq->lock); return rq->clock; } static inline u64 rq_clock_task(struct rq *rq) { + lockdep_assert_held(&rq->lock); return rq->clock_task; }