Commit 4155fb48 authored by Tejun Heo's avatar Tejun Heo
Browse files

sched_ext: Pass held rq to SCX_CALL_OP() for core_sched_before 



scx_prio_less() runs from core-sched's pick_next_task() path with rq
locked but invokes ops.core_sched_before() with NULL locked_rq, leaving
scx_locked_rq_state NULL. If the BPF callback calls a kfunc that
re-acquires rq based on scx_locked_rq() - e.g. scx_bpf_cpuperf_set(cpu)
- it re-acquires the already-held rq.

Pass task_rq(a).

Fixes: 7b0888b7 ("sched_ext: Implement core-sched support")
Cc: stable@vger.kernel.org # v6.12+
Reported-by: default avatarChris Mason <clm@meta.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarAndrea Righi <arighi@nvidia.com>
parent 207d76a3

kernel/sched/ext.c

+1 −1
Original line number Diff line number Diff line
@@ -3198,7 +3198,7 @@ bool scx_prio_less(const struct task_struct *a, const struct task_struct *b, 
	if (sch_a == sch_b && SCX_HAS_OP(sch_a, core_sched_before) &&

	    !scx_bypassing(sch_a, task_cpu(a)))

		return SCX_CALL_OP_2TASKS_RET(sch_a, core_sched_before,

					      NULL,

					      task_rq(a),

					      (struct task_struct *)a,

					      (struct task_struct *)b);

	else