From: Morten Rasmussen <morten.rasmussen@arm.com>
To: peterz@infradead.org, mingo@redhat.com
Cc: valentin.schneider@arm.com, dietmar.eggemann@arm.com,
vincent.guittot@linaro.org, gaku.inami.xh@renesas.com,
linux-kernel@vger.kernel.org,
Morten Rasmussen <morten.rasmussen@arm.com>
Subject: [PATCHv2 6/7] sched: Wrap rq->rd->overload accesses with READ/WRITE_ONCE
Date: Thu, 15 Mar 2018 14:47:03 +0000 [thread overview]
Message-ID: <1521125224-15434-7-git-send-email-morten.rasmussen@arm.com> (raw)
In-Reply-To: <1521125224-15434-1-git-send-email-morten.rasmussen@arm.com>
From: Valentin Schneider <valentin.schneider@arm.com>
This variable can be read and set locklessly within update_sd_lb_stats().
As such, READ/WRITE_ONCE are added to make sure nothing terribly wrong
can happen because of the compiler.
cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
---
kernel/sched/fair.c | 6 +++---
kernel/sched/sched.h | 4 ++--
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index fe4824a37302..4e79ec8760be 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8220,8 +8220,8 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
if (!env->sd->parent) {
/* update overload indicator if we are at root domain */
- if (env->dst_rq->rd->overload != overload)
- env->dst_rq->rd->overload = overload;
+ if (READ_ONCE(env->dst_rq->rd->overload) != overload)
+ WRITE_ONCE(env->dst_rq->rd->overload, overload);
}
}
@@ -9659,7 +9659,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
rq_unpin_lock(this_rq, rf);
if (this_rq->avg_idle < sysctl_sched_migration_cost ||
- !this_rq->rd->overload) {
+ !READ_ONCE(this_rq->rd->overload)) {
rcu_read_lock();
sd = rcu_dereference_check_sched_domain(this_rq->sd);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 5379f647016d..31847b7f7d47 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1651,8 +1651,8 @@ static inline void add_nr_running(struct rq *rq, unsigned count)
if (prev_nr < 2 && rq->nr_running >= 2) {
#ifdef CONFIG_SMP
- if (!rq->rd->overload)
- rq->rd->overload = 1;
+ if (!READ_ONCE(rq->rd->overload))
+ WRITE_ONCE(rq->rd->overload, 1);
#endif
}
--
2.7.4
next prev parent reply other threads:[~2018-03-15 14:47 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-15 14:46 [PATCHv2 0/7] sched/fair: Migrate 'misfit' tasks on asymmetric capacity systems Morten Rasmussen
2018-03-15 14:46 ` [PATCHv2 1/7] sched: Add static_key for asymmetric cpu capacity optimizations Morten Rasmussen
2018-04-27 14:04 ` [PATCHv2,1/7] " Jiada Wang
2018-04-29 19:09 ` Valentin Schneider
2018-03-15 14:46 ` [PATCHv2 2/7] sched/fair: Add group_misfit_task load-balance type Morten Rasmussen
2018-04-11 10:45 ` Peter Zijlstra
2018-03-15 14:47 ` [PATCHv2 3/7] sched/fair: Consider misfit tasks when load-balancing Morten Rasmussen
2018-04-11 10:46 ` Peter Zijlstra
2018-04-11 10:53 ` Peter Zijlstra
2018-03-15 14:47 ` [PATCHv2 4/7] sched/fair: Kick nohz balance if rq->misfit_task Morten Rasmussen
2018-03-15 14:47 ` [PATCHv2 5/7] sched: Change root_domain->overload type to int Morten Rasmussen
2018-03-15 14:47 ` Morten Rasmussen [this message]
2018-03-15 14:47 ` [PATCHv2 7/7] sched/fair: Set sd->overload when misfit Morten Rasmussen
2018-03-20 5:30 ` [PATCHv2 0/7] sched/fair: Migrate 'misfit' tasks on asymmetric capacity systems Gaku Inami
2018-03-20 9:17 ` Morten Rasmussen
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