linux-kernel - [PATCH 12/46] sched_ext: Add the @sch parameter to scx_dsq_insert

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Message-ID: <20250920005931.2753828-13-tj@kernel.org>
Date: Fri, 19 Sep 2025 14:58:35 -1000
From: Tejun Heo <tj@...nel.org>
To: void@...ifault.com,
	arighi@...dia.com,
	multics69@...il.com
Cc: linux-kernel@...r.kernel.org,
	sched-ext@...ts.linux.dev,
	memxor@...il.com,
	bpf@...r.kernel.org,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 12/46] sched_ext: Add the @sch parameter to scx_dsq_insert_preamble/commit()

In preparation for multiple scheduler support, add the @sch parameter to
scx_dsq_insert_preamble/commit() and update the callers to read $scx_root
and pass it in. The passed in @sch parameter is not used yet.

Signed-off-by: Tejun Heo <tj@...nel.org>
---
 kernel/sched/ext.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 56ca09f46d1e..1455f8c56d5c 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -5240,7 +5240,8 @@ void __init init_sched_ext_class(void)
 /********************************************************************************
  * Helpers that can be called from the BPF scheduler.
  */
-static bool scx_dsq_insert_preamble(struct task_struct *p, u64 enq_flags)
+static bool scx_dsq_insert_preamble(struct scx_sched *sch, struct task_struct *p,
+				    u64 enq_flags)
 {
 	if (!scx_kf_allowed(SCX_KF_ENQUEUE | SCX_KF_DISPATCH))
 		return false;
@@ -5260,8 +5261,8 @@ static bool scx_dsq_insert_preamble(struct task_struct *p, u64 enq_flags)
 	return true;
 }
 
-static void scx_dsq_insert_commit(struct task_struct *p, u64 dsq_id,
-				  u64 enq_flags)
+static void scx_dsq_insert_commit(struct scx_sched *sch, struct task_struct *p,
+				  u64 dsq_id, u64 enq_flags)
 {
 	struct scx_dsp_ctx *dspc = this_cpu_ptr(scx_dsp_ctx);
 	struct task_struct *ddsp_task;
@@ -5325,7 +5326,14 @@ __bpf_kfunc_start_defs();
 __bpf_kfunc void scx_bpf_dsq_insert(struct task_struct *p, u64 dsq_id, u64 slice,
 				    u64 enq_flags)
 {
-	if (!scx_dsq_insert_preamble(p, enq_flags))
+	struct scx_sched *sch;
+
+	guard(rcu)();
+	sch = rcu_dereference(scx_root);
+	if (unlikely(!sch))
+		return;
+
+	if (!scx_dsq_insert_preamble(sch, p, enq_flags))
 		return;
 
 	if (slice)
@@ -5333,7 +5341,7 @@ __bpf_kfunc void scx_bpf_dsq_insert(struct task_struct *p, u64 dsq_id, u64 slice
 	else
 		p->scx.slice = p->scx.slice ?: 1;
 
-	scx_dsq_insert_commit(p, dsq_id, enq_flags);
+	scx_dsq_insert_commit(sch, p, dsq_id, enq_flags);
 }
 
 /**
@@ -5360,7 +5368,14 @@ __bpf_kfunc void scx_bpf_dsq_insert(struct task_struct *p, u64 dsq_id, u64 slice
 __bpf_kfunc void scx_bpf_dsq_insert_vtime(struct task_struct *p, u64 dsq_id,
 					  u64 slice, u64 vtime, u64 enq_flags)
 {
-	if (!scx_dsq_insert_preamble(p, enq_flags))
+	struct scx_sched *sch;
+
+	guard(rcu)();
+	sch = rcu_dereference(scx_root);
+	if (unlikely(!sch))
+		return;
+
+	if (!scx_dsq_insert_preamble(sch, p, enq_flags))
 		return;
 
 	if (slice)
@@ -5370,7 +5385,7 @@ __bpf_kfunc void scx_bpf_dsq_insert_vtime(struct task_struct *p, u64 dsq_id,
 
 	p->scx.dsq_vtime = vtime;
 
-	scx_dsq_insert_commit(p, dsq_id, enq_flags | SCX_ENQ_DSQ_PRIQ);
+	scx_dsq_insert_commit(sch, p, dsq_id, enq_flags | SCX_ENQ_DSQ_PRIQ);
 }
 
 __bpf_kfunc_end_defs();
-- 
2.51.0