On Tue, Jan 15, 2019 at 10:15:02AM +0000, Patrick Bellasi wrote: > +static inline void > +uclamp_task_update_active(struct task_struct *p, unsigned int clamp_id) > +{ > + struct rq_flags rf; > + struct rq *rq; > + > + /* > + * Lock the task and the CPU where the task is (or was) queued. > + * > + * We might lock the (previous) rq of a !RUNNABLE task, but that's the > + * price to pay to safely serialize util_{min,max} updates with > + * enqueues, dequeues and migration operations. > + * This is the same locking schema used by __set_cpus_allowed_ptr(). > + */ > + rq = task_rq_lock(p, &rf); > + > + /* > + * Setting the clamp bucket is serialized by task_rq_lock(). > + * If the task is not yet RUNNABLE and its task_struct is not > + * affecting a valid clamp bucket, the next time it's enqueued, > + * it will already see the updated clamp bucket value. > + */ > + if (!p->uclamp[clamp_id].active) > + goto done; > + > + uclamp_cpu_dec_id(p, rq, clamp_id); > + uclamp_cpu_inc_id(p, rq, clamp_id); > + > +done: > + task_rq_unlock(rq, p, &rf); > +} > @@ -1008,11 +1043,11 @@ static int __setscheduler_uclamp(struct task_struct *p, > > mutex_lock(&uclamp_mutex); > if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) { > - uclamp_bucket_inc(&p->uclamp[UCLAMP_MIN], > + uclamp_bucket_inc(p, &p->uclamp[UCLAMP_MIN], > UCLAMP_MIN, lower_bound); > } > if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) { > - uclamp_bucket_inc(&p->uclamp[UCLAMP_MAX], > + uclamp_bucket_inc(p, &p->uclamp[UCLAMP_MAX], > UCLAMP_MAX, upper_bound); > } > mutex_unlock(&uclamp_mutex); But.... __sched_setscheduler() actually does the whole dequeue + enqueue thing already ?!? See where it does __setscheduler().