From: Tejun Heo <tj@kernel.org>
Date: Tue, 29 Apr 2025 18:40:11 +0000 (-1000)
Subject: sched_ext: Clean up SCX_EXIT_NONE handling in scx_disable_workfn()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=9ba7f37e5b39654e657df83c266c24ee7bbc2296;p=users%2Fwilly%2Fxarray.git

sched_ext: Clean up SCX_EXIT_NONE handling in scx_disable_workfn()

With the global states and disable machinery moved into scx_sched,
scx_disable_workfn() can only be scheduled and run for the specific
scheduler instance. This makes it impossible for scx_disable_workfn() to see
SCX_EXIT_NONE. Turn that condition into WARN_ON_ONCE().

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
---

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index a21390c9e977..66d21c7cdff7 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -4752,13 +4752,9 @@ static void scx_disable_workfn(struct kthread_work *work)
 
 	kind = atomic_read(&sch->exit_kind);
 	while (true) {
-		/*
-		 * NONE indicates that a new scx_ops has been registered since
-		 * disable was scheduled - don't kill the new ops. DONE
-		 * indicates that the ops has already been disabled.
-		 */
-		if (kind == SCX_EXIT_NONE || kind == SCX_EXIT_DONE)
+		if (kind == SCX_EXIT_DONE)	/* already disabled? */
 			return;
+		WARN_ON_ONCE(kind == SCX_EXIT_NONE);
 		if (atomic_try_cmpxchg(&sch->exit_kind, &kind, SCX_EXIT_DONE))
 			break;
 	}