Re: [PATCH 01/15] sched_ext: Relocate scx_bpf_task_cgroup() and its BTF_ID to the end of kfunc section

[Emil Tsalapatis]

On Fri Mar 6, 2026 at 2:06 PM EST, Tejun Heo wrote:
> Move scx_bpf_task_cgroup() kfunc definition and its BTF_ID entry to the end
> of the kfunc section before __bpf_kfunc_end_defs() for cleaner code
> organization.
>
> No functional changes.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>

Reviewed-by: Emil Tsalapatis <emil@xxxxxxxxxxxxxxx>

> ---
>  kernel/sched/ext.c | 78 +++++++++++++++++++++++-----------------------
>  1 file changed, 39 insertions(+), 39 deletions(-)
>
> diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
> index e25b3593dd30..fe222df1d494 100644
> --- a/kernel/sched/ext.c
> +++ b/kernel/sched/ext.c
> @@ -8628,43 +8628,6 @@ __bpf_kfunc struct task_struct *scx_bpf_cpu_curr(s32 cpu, const struct bpf_prog_
>  	return rcu_dereference(cpu_rq(cpu)->curr);
>  }
>  
> -/**
> - * scx_bpf_task_cgroup - Return the sched cgroup of a task
> - * @p: task of interest
> - * @aux: implicit BPF argument to access bpf_prog_aux hidden from BPF progs
> - *
> - * @p->sched_task_group->css.cgroup represents the cgroup @p is associated with
> - * from the scheduler's POV. SCX operations should use this function to
> - * determine @p's current cgroup as, unlike following @p->cgroups,
> - * @p->sched_task_group is protected by @p's rq lock and thus atomic w.r.t. all
> - * rq-locked operations. Can be called on the parameter tasks of rq-locked
> - * operations. The restriction guarantees that @p's rq is locked by the caller.
> - */
> -#ifdef CONFIG_CGROUP_SCHED
> -__bpf_kfunc struct cgroup *scx_bpf_task_cgroup(struct task_struct *p,
> -					       const struct bpf_prog_aux *aux)
> -{
> -	struct task_group *tg = p->sched_task_group;
> -	struct cgroup *cgrp = &cgrp_dfl_root.cgrp;
> -	struct scx_sched *sch;
> -
> -	guard(rcu)();
> -
> -	sch = scx_prog_sched(aux);
> -	if (unlikely(!sch))
> -		goto out;
> -
> -	if (!scx_kf_allowed_on_arg_tasks(sch, __SCX_KF_RQ_LOCKED, p))
> -		goto out;
> -
> -	cgrp = tg_cgrp(tg);
> -
> -out:
> -	cgroup_get(cgrp);
> -	return cgrp;
> -}
> -#endif
> -
>  /**
>   * scx_bpf_now - Returns a high-performance monotonically non-decreasing
>   * clock for the current CPU. The clock returned is in nanoseconds.
> @@ -8779,6 +8742,43 @@ __bpf_kfunc void scx_bpf_events(struct scx_event_stats *events,
>  	memcpy(events, &e_sys, events__sz);
>  }
>  
> +#ifdef CONFIG_CGROUP_SCHED
> +/**
> + * scx_bpf_task_cgroup - Return the sched cgroup of a task
> + * @p: task of interest
> + * @aux: implicit BPF argument to access bpf_prog_aux hidden from BPF progs
> + *
> + * @p->sched_task_group->css.cgroup represents the cgroup @p is associated with
> + * from the scheduler's POV. SCX operations should use this function to
> + * determine @p's current cgroup as, unlike following @p->cgroups,
> + * @p->sched_task_group is protected by @p's rq lock and thus atomic w.r.t. all
> + * rq-locked operations. Can be called on the parameter tasks of rq-locked
> + * operations. The restriction guarantees that @p's rq is locked by the caller.
> + */
> +__bpf_kfunc struct cgroup *scx_bpf_task_cgroup(struct task_struct *p,
> +					       const struct bpf_prog_aux *aux)
> +{
> +	struct task_group *tg = p->sched_task_group;
> +	struct cgroup *cgrp = &cgrp_dfl_root.cgrp;
> +	struct scx_sched *sch;
> +
> +	guard(rcu)();
> +
> +	sch = scx_prog_sched(aux);
> +	if (unlikely(!sch))
> +		goto out;
> +
> +	if (!scx_kf_allowed_on_arg_tasks(sch, __SCX_KF_RQ_LOCKED, p))
> +		goto out;
> +
> +	cgrp = tg_cgrp(tg);
> +
> +out:
> +	cgroup_get(cgrp);
> +	return cgrp;
> +}
> +#endif	/* CONFIG_CGROUP_SCHED */
> +
>  __bpf_kfunc_end_defs();
>  
>  BTF_KFUNCS_START(scx_kfunc_ids_any)
> @@ -8808,11 +8808,11 @@ BTF_ID_FLAGS(func, scx_bpf_task_cpu, KF_RCU)
>  BTF_ID_FLAGS(func, scx_bpf_cpu_rq, KF_IMPLICIT_ARGS)
>  BTF_ID_FLAGS(func, scx_bpf_locked_rq, KF_IMPLICIT_ARGS | KF_RET_NULL)
>  BTF_ID_FLAGS(func, scx_bpf_cpu_curr, KF_IMPLICIT_ARGS | KF_RET_NULL | KF_RCU_PROTECTED)
> +BTF_ID_FLAGS(func, scx_bpf_now)
> +BTF_ID_FLAGS(func, scx_bpf_events)
>  #ifdef CONFIG_CGROUP_SCHED
>  BTF_ID_FLAGS(func, scx_bpf_task_cgroup, KF_IMPLICIT_ARGS | KF_RCU | KF_ACQUIRE)
>  #endif
> -BTF_ID_FLAGS(func, scx_bpf_now)
> -BTF_ID_FLAGS(func, scx_bpf_events)
>  BTF_KFUNCS_END(scx_kfunc_ids_any)
>  
>  static const struct btf_kfunc_id_set scx_kfunc_set_any = {