1 files changed, 25 insertions, 33 deletions

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 1d0f634725a6..7b4aa5809c0f 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -434,14 +434,13 @@ static u64 window_update(struct psi_window *win, u64 now, u64 value)
 	return growth;
 }
 
-static u64 update_triggers(struct psi_group *group, u64 now, bool *update_total,
+static void update_triggers(struct psi_group *group, u64 now,
 						   enum psi_aggregators aggregator)
 {
 	struct psi_trigger *t;
 	u64 *total = group->total[aggregator];
 	struct list_head *triggers;
 	u64 *aggregator_total;
-	*update_total = false;
 
 	if (aggregator == PSI_AVGS) {
 		triggers = &group->avg_triggers;
@@ -471,14 +470,6 @@ static u64 update_triggers(struct psi_group *group, u64 now, bool *update_total,
 		 * events without dropping any).
 		 */
 		if (new_stall) {
-			/*
-			 * Multiple triggers might be looking at the same state,
-			 * remember to update group->polling_total[] once we've
-			 * been through all of them. Also remember to extend the
-			 * polling time if we see new stall activity.
-			 */
-			*update_total = true;
-
 			/* Calculate growth since last update */
 			growth = window_update(&t->win, now, total[t->state]);
 			if (!t->pending_event) {
@@ -503,8 +494,6 @@ static u64 update_triggers(struct psi_group *group, u64 now, bool *update_total,
 		/* Reset threshold breach flag once event got generated */
 		t->pending_event = false;
 	}
-
-	return now + group->rtpoll_min_period;
 }
 
 static u64 update_averages(struct psi_group *group, u64 now)
@@ -565,7 +554,6 @@ static void psi_avgs_work(struct work_struct *work)
 	struct delayed_work *dwork;
 	struct psi_group *group;
 	u32 changed_states;
-	bool update_total;
 	u64 now;
 
 	dwork = to_delayed_work(work);
@@ -584,7 +572,7 @@ static void psi_avgs_work(struct work_struct *work)
 	 * go - see calc_avgs() and missed_periods.
 	 */
 	if (now >= group->avg_next_update) {
-		update_triggers(group, now, &update_total, PSI_AVGS);
+		update_triggers(group, now, PSI_AVGS);
 		group->avg_next_update = update_averages(group, now);
 	}
 
@@ -608,7 +596,7 @@ static void init_rtpoll_triggers(struct psi_group *group, u64 now)
 	group->rtpoll_next_update = now + group->rtpoll_min_period;
 }
 
-/* Schedule polling if it's not already scheduled or forced. */
+/* Schedule rtpolling if it's not already scheduled or forced. */
 static void psi_schedule_rtpoll_work(struct psi_group *group, unsigned long delay,
 				   bool force)
 {
@@ -640,7 +628,6 @@ static void psi_rtpoll_work(struct psi_group *group)
 {
 	bool force_reschedule = false;
 	u32 changed_states;
-	bool update_total;
 	u64 now;
 
 	mutex_lock(&group->rtpoll_trigger_lock);
@@ -649,37 +636,37 @@ static void psi_rtpoll_work(struct psi_group *group)
 
 	if (now > group->rtpoll_until) {
 		/*
-		 * We are either about to start or might stop polling if no
-		 * state change was recorded. Resetting poll_scheduled leaves
+		 * We are either about to start or might stop rtpolling if no
+		 * state change was recorded. Resetting rtpoll_scheduled leaves
 		 * a small window for psi_group_change to sneak in and schedule
-		 * an immediate poll_work before we get to rescheduling. One
-		 * potential extra wakeup at the end of the polling window
-		 * should be negligible and polling_next_update still keeps
+		 * an immediate rtpoll_work before we get to rescheduling. One
+		 * potential extra wakeup at the end of the rtpolling window
+		 * should be negligible and rtpoll_next_update still keeps
 		 * updates correctly on schedule.
 		 */
 		atomic_set(&group->rtpoll_scheduled, 0);
 		/*
-		 * A task change can race with the poll worker that is supposed to
+		 * A task change can race with the rtpoll worker that is supposed to
 		 * report on it. To avoid missing events, ensure ordering between
-		 * poll_scheduled and the task state accesses, such that if the poll
-		 * worker misses the state update, the task change is guaranteed to
-		 * reschedule the poll worker:
+		 * rtpoll_scheduled and the task state accesses, such that if the
+		 * rtpoll worker misses the state update, the task change is
+		 * guaranteed to reschedule the rtpoll worker:
 		 *
-		 * poll worker:
-		 *   atomic_set(poll_scheduled, 0)
+		 * rtpoll worker:
+		 *   atomic_set(rtpoll_scheduled, 0)
 		 *   smp_mb()
 		 *   LOAD states
 		 *
 		 * task change:
 		 *   STORE states
-		 *   if atomic_xchg(poll_scheduled, 1) == 0:
-		 *     schedule poll worker
+		 *   if atomic_xchg(rtpoll_scheduled, 1) == 0:
+		 *     schedule rtpoll worker
 		 *
 		 * The atomic_xchg() implies a full barrier.
 		 */
 		smp_mb();
 	} else {
-		/* Polling window is not over, keep rescheduling */
+		/* The rtpolling window is not over, keep rescheduling */
 		force_reschedule = true;
 	}
 
@@ -687,7 +674,7 @@ static void psi_rtpoll_work(struct psi_group *group)
 	collect_percpu_times(group, PSI_POLL, &changed_states);
 
 	if (changed_states & group->rtpoll_states) {
-		/* Initialize trigger windows when entering polling mode */
+		/* Initialize trigger windows when entering rtpolling mode */
 		if (now > group->rtpoll_until)
 			init_rtpoll_triggers(group, now);
 
@@ -706,10 +693,12 @@ static void psi_rtpoll_work(struct psi_group *group)
 	}
 
 	if (now >= group->rtpoll_next_update) {
-		group->rtpoll_next_update = update_triggers(group, now, &update_total, PSI_POLL);
-		if (update_total)
+		if (changed_states & group->rtpoll_states) {
+			update_triggers(group, now, PSI_POLL);
 			memcpy(group->rtpoll_total, group->total[PSI_POLL],
 				   sizeof(group->rtpoll_total));
+		}
+		group->rtpoll_next_update = now + group->rtpoll_min_period;
 	}
 
 	psi_schedule_rtpoll_work(group,
@@ -1009,6 +998,9 @@ void psi_account_irqtime(struct task_struct *task, u32 delta)
 	struct psi_group_cpu *groupc;
 	u64 now;
 
+	if (static_branch_likely(&psi_disabled))
+		return;
+
 	if (!task->pid)
 		return;