diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 27 |
1 files changed, 16 insertions, 11 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 85c22f0f8de8..0a35a82e4792 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7876,21 +7876,26 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool { struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask); int i, cpu, idle_cpu = -1, nr = INT_MAX; - struct sched_domain_shared *sd_share; - - cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr); if (sched_feat(SIS_UTIL)) { - sd_share = rcu_dereference_all(per_cpu(sd_llc_shared, target)); - if (sd_share) { - /* because !--nr is the condition to stop scan */ - nr = READ_ONCE(sd_share->nr_idle_scan) + 1; - /* overloaded LLC is unlikely to have idle cpu/core */ - if (nr == 1) - return -1; - } + /* + * Increment because !--nr is the condition to stop scan. + * + * Since "sd" is "sd_llc" for target CPU dereferenced in the + * caller, it is safe to directly dereference "sd->shared". + * Topology bits always ensure it assigned for "sd_llc" abd it + * cannot disappear as long as we have a RCU protected + * reference to one the associated "sd" here. + */ + nr = READ_ONCE(sd->shared->nr_idle_scan) + 1; + /* overloaded LLC is unlikely to have idle cpu/core */ + if (nr == 1) + return -1; } + if (!cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr)) + return -1; + if (static_branch_unlikely(&sched_cluster_active)) { struct sched_group *sg = sd->groups; |