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: [PATCHv3 7/9] sched: Wrap rq->rd->overload accesses with READ/WRITE_ONCE
Date: Wed, 20 Jun 2018 10:05:47 +0100 [thread overview]
Message-ID: <1529485549-5191-8-git-send-email-morten.rasmussen@arm.com> (raw)
In-Reply-To: <1529485549-5191-1-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 545fa3600894..9dd147c71dd0 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8431,8 +8431,8 @@ 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);
}
}
@@ -9875,7 +9875,7 @@ 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 f945edadd2c5..791d9badad31 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1665,8 +1665,8 @@ 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:[~2018-06-20 9:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-20 9:05 [PATCHv3 0/9] sched/fair: Migrate 'misfit' tasks on asymmetric capacity systems Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 1/9] sched: Add static_key for asymmetric cpu capacity optimizations Morten Rasmussen
2018-06-22 8:22 ` Quentin Perret
2018-06-22 14:36 ` Morten Rasmussen
2018-06-27 15:41 ` Dietmar Eggemann
2018-06-28 8:48 ` Morten Rasmussen
2018-06-28 17:16 ` Dietmar Eggemann
2018-07-02 8:36 ` Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 2/9] sched/fair: Add group_misfit_task load-balance type Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 3/9] sched: Add sched_group per-cpu max capacity Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 4/9] sched/fair: Consider misfit tasks when load-balancing Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 5/9] sched/fair: Kick nohz balance if rq->misfit_task Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 6/9] sched: Change root_domain->overload type to int Morten Rasmussen
2018-06-20 9:05 ` Morten Rasmussen [this message]
2018-06-20 9:05 ` [PATCHv3 8/9] sched/fair: Set sd->overload when misfit Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 9/9] sched/fair: Don't move tasks to lower capacity cpus unless necessary Morten Rasmussen
2018-07-03 2:28 ` [PATCHv3 0/9] sched/fair: Migrate 'misfit' tasks on asymmetric capacity systems Gaku Inami
2018-07-04 10:33 ` Morten Rasmussen
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