[PATCH 12/12] sched_ext: Clean up SCX_EXIT_NONE handling in scx_disable_workfn()

Tejun Heo
2025-04-25T21:58:57Z

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>
---
kernel/sched/ext.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 06973ec6177a..a35095047c5f 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;
}
--
2.49.0