linux-kernel - [PATCH] sched_ext: Replace rq_lock() to raw_spin_rq_lock() in scx_ops

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Message-ID: <20250108025521.85877-1-changwoo@igalia.com>
Date: Wed,  8 Jan 2025 11:55:21 +0900
From: Changwoo Min <changwoo@...lia.com>
To: tj@...nel.org,
	void@...ifault.com,
	arighi@...dia.com
Cc: kernel-dev@...lia.com,
	linux-kernel@...r.kernel.org,
	Changwoo Min <changwoo@...lia.com>
Subject: [PATCH] sched_ext: Replace rq_lock() to raw_spin_rq_lock() in scx_ops_bypass()

scx_ops_bypass() iterates all CPUs to re-enqueue all the scx tasks.
For each CPU, it acquires a lock using rq_lock() regardless of whether
a CPU is offline or the CPU is currently running a task in a higher
scheduler class (e.g., deadline). The rq_lock() is supposed to be used
for online CPUs, and the use of rq_lock() may trigger an unnecessary
warning in rq_pin_lock(). Therefore, replace rq_lock() to
raw_spin_rq_lock() in scx_ops_bypass().

Signed-off-by: Changwoo Min <changwoo@...lia.com>
---
 kernel/sched/ext.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 8fe64c27004e..741398f3e730 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -4803,10 +4803,9 @@ static void scx_ops_bypass(bool bypass)
 	 */
 	for_each_possible_cpu(cpu) {
 		struct rq *rq = cpu_rq(cpu);
-		struct rq_flags rf;
 		struct task_struct *p, *n;
 
-		rq_lock(rq, &rf);
+		raw_spin_rq_lock(rq);
 
 		if (bypass) {
 			WARN_ON_ONCE(rq->scx.flags & SCX_RQ_BYPASSING);
@@ -4822,7 +4821,7 @@ static void scx_ops_bypass(bool bypass)
 		 * sees scx_rq_bypassing() before moving tasks to SCX.
 		 */
 		if (!scx_enabled()) {
-			rq_unlock(rq, &rf);
+			raw_spin_rq_unlock(rq);
 			continue;
 		}
 
@@ -4842,7 +4841,7 @@ static void scx_ops_bypass(bool bypass)
 			sched_enq_and_set_task(&ctx);
 		}
 
-		rq_unlock(rq, &rf);
+		raw_spin_rq_unlock(rq);
 
 		/* resched to restore ticks and idle state */
 		resched_cpu(cpu);
-- 
2.47.1