Commit-ID: e90c8fe15a3bf93a23088bcf1a56a0fa391d4e50 Gitweb: https://git.kernel.org/tip/e90c8fe15a3bf93a23088bcf1a56a0fa391d4e50 Author: Valentin Schneider <[email protected]> AuthorDate: Wed, 4 Jul 2018 11:17:46 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 10 Sep 2018 11:05:52 +0200
sched/fair: Wrap rq->rd->overload accesses with READ/WRITE_ONCE() 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. Signed-off-by: Valentin Schneider <[email protected]> Signed-off-by: Morten Rasmussen <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- 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 23017939ecab..d9c4e97bfebd 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8058,8 +8058,8 @@ next_group: 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); } } @@ -9502,7 +9502,7 @@ 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 4d181478c5b8..938063639793 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1697,8 +1697,8 @@ 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 }
