[PATCH 03/30] sched: Restructure sched_class order sanity checks in sched_init()

Tejun Heo
2023-01-28T00:17:02Z

Currently, sched_init() checks that the sched_class'es are in the expected
order by testing each adjacency which is a bit brittle and makes it
cumbersome to add optional sched_class'es. Instead, let's verify whether
they're in the expected order using sched_class_above() which is what
matters.

Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: David Vernet <dvernet@meta.com>
---
kernel/sched/core.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bfc3312f305a..65f21f8bf738 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9721,12 +9721,12 @@ void __init sched_init(void)
int i;

/* Make sure the linker didn't screw up */
- BUG_ON(&idle_sched_class != &fair_sched_class + 1 ||
- &fair_sched_class != &rt_sched_class + 1 ||
- &rt_sched_class != &dl_sched_class + 1);
#ifdef CONFIG_SMP
- BUG_ON(&dl_sched_class != &stop_sched_class + 1);
+ BUG_ON(!sched_class_above(&stop_sched_class, &dl_sched_class));
#endif
+ BUG_ON(!sched_class_above(&dl_sched_class, &rt_sched_class));
+ BUG_ON(!sched_class_above(&rt_sched_class, &fair_sched_class));
+ BUG_ON(!sched_class_above(&fair_sched_class, &idle_sched_class));

wait_bit_init();

--
2.39.1