From: Su Zhidao <[email protected]> scx_bypass_lb_timerfn() runs in softirq (BH) context, so rcu_dereference_bh() is the correct RCU accessor. The previous rcu_dereference_all() suppresses all sparse warnings and masks potential RCU context issues.
Add a comment noting this is a transitional state: when multi-scheduler support lands, the bypass LB timer will become per-scheduler and the global scx_root reference will be removed. Signed-off-by: Su Zhidao <[email protected]> --- kernel/sched/ext.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 053d99c58802..c269e489902c 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -4170,7 +4170,13 @@ static void scx_bypass_lb_timerfn(struct timer_list *timer) int node; u32 intv_us; - sch = rcu_dereference_all(scx_root); + /* + * scx_bypass_lb_timer is a global timer that fires in softirq + * context while bypass mode is active. Use rcu_dereference_bh() + * matching the BH context. When multi-scheduler support lands, + * this timer will become per-scheduler instance. + */ + sch = rcu_dereference_bh(scx_root); if (unlikely(!sch) || !READ_ONCE(scx_bypass_depth)) return; -- 2.43.0
