sched: Simplify ttwu_runnable()

Note that both proxy and delayed tasks have ->is_blocked set. Use this one
condition to guard both paths.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260526113322.714832584%40infradead.org

Author: Peter Zijlstra

kernel/sched/core.c

@@ -3764,9 +3764,6 @@ static inline void proxy_reset_donor(struct rq *rq)
  */
 static inline bool proxy_needs_return(struct rq *rq, struct task_struct *p)
 {
-	if (!p->is_blocked)
-		return false;
-
 	/*
 	 * Typically per __set_task_cpu(), task_cpu(p) == p->wake_cpu.
 	 *
@@ -3875,10 +3872,12 @@ static int ttwu_runnable(struct task_struct *p, int wake_flags)
 		return 0;
 
 	update_rq_clock(rq);
-	if (p->se.sched_delayed)
-		enqueue_task(rq, p, ENQUEUE_NOCLOCK | ENQUEUE_DELAYED);
-	if (proxy_needs_return(rq, p))
-		return 0;
+	if (p->is_blocked) {
+		if (p->se.sched_delayed)
+			enqueue_task(rq, p, ENQUEUE_NOCLOCK | ENQUEUE_DELAYED);
+		if (proxy_needs_return(rq, p))
+			return 0;
+	}
 	if (!task_on_cpu(rq, p)) {
 		/*
 		 * When on_rq && !on_cpu the task is preempted, see if