[PATCH 6.12.y 1/2] sched_ext: Factor out local_dsq_post_enq() from dispatch_enqueue()

[Sasha Levin <sashal@kernel.org>]

From: Tejun Heo <tj@kernel.org>

[ Upstream commit 530b6637c79e728d58f1d9b66bd4acf4b735b86d ]

Factor out local_dsq_post_enq() which performs post-enqueue handling for
local DSQs - triggering resched_curr() if SCX_ENQ_PREEMPT is specified or if
the current CPU is idle. No functional change.

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

Cc: stable@vger.kernel.org # v6.12+
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
[ adapted function placement to precede dispatch_enqueue() due to missing refill_task_slice_dfl() function in stable branch ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/sched/ext.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index ad1d438b3085..54e194d08d92 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1668,6 +1668,22 @@ static void dsq_mod_nr(struct scx_dispatch_q *dsq, s32 delta)
 	WRITE_ONCE(dsq->nr, dsq->nr + delta);
 }
 
+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_dispatch_q *dsq, struct task_struct *p,
 			     u64 enq_flags)
 {
@@ -1765,22 +1781,10 @@ static void dispatch_enqueue(struct scx_dispatch_q *dsq, struct task_struct *p,
 	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,
-- 
2.51.0