linux-kernel - [RFC][PATCH 3/5] sched: Split up ttwu

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Message-ID: <20250520101727.732703833@infradead.org>
Date: Tue, 20 May 2025 11:45:41 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: mingo@...hat.com,
 juri.lelli@...hat.com,
 vincent.guittot@...aro.org,
 dietmar.eggemann@....com,
 rostedt@...dmis.org,
 bsegall@...gle.com,
 mgorman@...e.de,
 vschneid@...hat.com,
 clm@...a.com
Cc: linux-kernel@...r.kernel.org,
 peterz@...radead.org
Subject: [RFC][PATCH 3/5] sched: Split up ttwu_runnable()

Split up ttwu_runnable() in preparation for more changes.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/sched/core.c  |   43 +++++++++++++++++++++----------------------
 kernel/sched/sched.h |    5 +++++
 2 files changed, 26 insertions(+), 22 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3765,6 +3765,25 @@ ttwu_do_activate(struct rq *rq, struct t
 #endif
 }
 
+static int __ttwu_runnable(struct rq *rq, struct task_struct *p, int wake_flags)
+{
+	if (!task_on_rq_queued(p))
+		return 0;
+
+	update_rq_clock(rq);
+	if (p->se.sched_delayed)
+		enqueue_task(rq, p, ENQUEUE_NOCLOCK | ENQUEUE_DELAYED);
+	if (!task_on_cpu(rq, p)) {
+		/*
+		 * When on_rq && !on_cpu the task is preempted, see if
+		 * it should preempt the task that is current now.
+		 */
+		wakeup_preempt(rq, p, wake_flags);
+	}
+	ttwu_do_wakeup(p);
+	return 1;
+}
+
 /*
  * Consider @p being inside a wait loop:
  *
@@ -3792,28 +3811,8 @@ ttwu_do_activate(struct rq *rq, struct t
  */
 static int ttwu_runnable(struct task_struct *p, int wake_flags)
 {
-	struct rq_flags rf;
-	struct rq *rq;
-	int ret = 0;
-
-	rq = __task_rq_lock(p, &rf);
-	if (task_on_rq_queued(p)) {
-		update_rq_clock(rq);
-		if (p->se.sched_delayed)
-			enqueue_task(rq, p, ENQUEUE_NOCLOCK | ENQUEUE_DELAYED);
-		if (!task_on_cpu(rq, p)) {
-			/*
-			 * When on_rq && !on_cpu the task is preempted, see if
-			 * it should preempt the task that is current now.
-			 */
-			wakeup_preempt(rq, p, wake_flags);
-		}
-		ttwu_do_wakeup(p);
-		ret = 1;
-	}
-	__task_rq_unlock(rq, &rf);
-
-	return ret;
+	CLASS(__task_rq_lock, guard)(p);
+	return __ttwu_runnable(guard.rq, p, wake_flags);
 }
 
 #ifdef CONFIG_SMP
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1831,6 +1831,11 @@ task_rq_unlock(struct rq *rq, struct tas
 	raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
 }
 
+DEFINE_LOCK_GUARD_1(__task_rq_lock, struct task_struct,
+		    _T->rq = __task_rq_lock(_T->lock, &_T->rf),
+		    __task_rq_unlock(_T->rq, &_T->rf),
+		    struct rq *rq; struct rq_flags rf)
+
 DEFINE_LOCK_GUARD_1(task_rq_lock, struct task_struct,
 		    _T->rq = task_rq_lock(_T->lock, &_T->rf),
 		    task_rq_unlock(_T->rq, _T->lock, &_T->rf),