linux-kernel - [PATCH 1/2] sched_ext: Factor out local_dsq_post_enq() from dispatch

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Message-ID: <20251211224809.3383633-2-tj@kernel.org>
Date: Thu, 11 Dec 2025 12:48:08 -1000
From: Tejun Heo <tj@...nel.org>
To: Andrea Righi <arighi@...dia.com>,
	Changwoo Min <changwoo@...lia.com>,
	David Vernet <void@...ifault.com>
Cc: Emil Tsalapatis <emil@...alapatis.com>,
	linux-kernel@...r.kernel.org,
	sched-ext@...ts.linux.dev,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 1/2] sched_ext: Factor out local_dsq_post_enq() from dispatch_enqueue()

Factor out local_dsq_post_enq() which performs post-enqueue handling for
local DSQs - triggering preemption or resched_curr() if the enqueued task
has higher priority than the currently running task. No functional change.

This will be used by the next patch to fix move_local_task_to_local_dsq().

Signed-off-by: Tejun Heo <tj@...nel.org>
---
 kernel/sched/ext.c |   34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -975,6 +975,22 @@ static void refill_task_slice_dfl(struct
 	__scx_add_event(sch, SCX_EV_REFILL_SLICE_DFL, 1);
 }
 
+static void local_dsq_post_enq(struct scx_dispatch_q *dsq, struct task_struct *p,
+			       u64 enq_flags)
+{
+	struct rq *rq = container_of(dsq, struct rq, scx.local_dsq);
+	bool preempt = false;
+
+	if ((enq_flags & SCX_ENQ_PREEMPT) && p != rq->curr &&
+	    rq->curr->sched_class == &ext_sched_class) {
+		rq->curr->scx.slice = 0;
+		preempt = true;
+	}
+
+	if (preempt || sched_class_above(&ext_sched_class, rq->curr->sched_class))
+		resched_curr(rq);
+}
+
 static void dispatch_enqueue(struct scx_sched *sch, struct scx_dispatch_q *dsq,
 			     struct task_struct *p, u64 enq_flags)
 {
@@ -1086,22 +1102,10 @@ static void dispatch_enqueue(struct scx_
 	if (enq_flags & SCX_ENQ_CLEAR_OPSS)
 		atomic_long_set_release(&p->scx.ops_state, SCX_OPSS_NONE);
 
-	if (is_local) {
-		struct rq *rq = container_of(dsq, struct rq, scx.local_dsq);
-		bool preempt = false;
-
-		if ((enq_flags & SCX_ENQ_PREEMPT) && p != rq->curr &&
-		    rq->curr->sched_class == &ext_sched_class) {
-			rq->curr->scx.slice = 0;
-			preempt = true;
-		}
-
-		if (preempt || sched_class_above(&ext_sched_class,
-						 rq->curr->sched_class))
-			resched_curr(rq);
-	} else {
+	if (is_local)
+		local_dsq_post_enq(dsq, p, enq_flags);
+	else
 		raw_spin_unlock(&dsq->lock);
-	}
 }
 
 static void task_unlink_from_dsq(struct task_struct *p,