sched: Simplify try_steal_cookie()

Use guards to reduce gotos and simplify control flow.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20230801211812.304154828@infradead.org

Author: Peter Zijlstra

kernel/sched/core.c

@@ -6298,19 +6298,19 @@ static bool try_steal_cookie(int this, int that)
 	unsigned long cookie;
 	bool success = false;
 
-	local_irq_disable();
-	double_rq_lock(dst, src);
+	guard(irq)();
+	guard(double_rq_lock)(dst, src);
 
 	cookie = dst->core->core_cookie;
 	if (!cookie)
-		goto unlock;
+		return false;
 
 	if (dst->curr != dst->idle)
-		goto unlock;
+		return false;
 
 	p = sched_core_find(src, cookie);
 	if (!p)
-		goto unlock;
+		return false;
 
 	do {
 		if (p == src->core_pick || p == src->curr)
@@ -6322,9 +6322,10 @@ static bool try_steal_cookie(int this, int that)
 		if (p->core_occupation > dst->idle->core_occupation)
 			goto next;
 		/*
-		 * sched_core_find() and sched_core_next() will ensure that task @p
-		 * is not throttled now, we also need to check whether the runqueue
-		 * of the destination CPU is being throttled.
+		 * sched_core_find() and sched_core_next() will ensure
+		 * that task @p is not throttled now, we also need to
+		 * check whether the runqueue of the destination CPU is
+		 * being throttled.
 		 */
 		if (sched_task_is_throttled(p, this))
 			goto next;
@@ -6342,10 +6343,6 @@ static bool try_steal_cookie(int this, int that)
 		p = sched_core_next(p, cookie);
 	} while (p);
 
-unlock:
-	double_rq_unlock(dst, src);
-	local_irq_enable();
-
 	return success;
 }