On Tue, Oct 15, 2024 at 7:42 PM Tianchen Ding <dtcccc@xxxxxxxxxxxxxxxxx> wrote:
>
> Save the searching time during bpf_scx_init.
>
> Signed-off-by: Tianchen Ding <dtcccc@xxxxxxxxxxxxxxxxx>
> ---
> kernel/sched/ext.c | 12 +++---------
> 1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
> index 609b9fb00d6f..1d11a96eefb8 100644
> --- a/kernel/sched/ext.c
> +++ b/kernel/sched/ext.c
> @@ -5343,7 +5343,7 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link)
>
> extern struct btf *btf_vmlinux;
> static const struct btf_type *task_struct_type;
> -static u32 task_struct_type_id;
> +BTF_ID_LIST_SINGLE(task_struct_btf_ids, struct, task_struct);
>
> static bool set_arg_maybe_null(const char *op, int arg_n, int off, int size,
> enum bpf_access_type type,
> @@ -5395,7 +5395,7 @@ static bool set_arg_maybe_null(const char *op, int arg_n, int off, int size,
> */
> info->reg_type = PTR_MAYBE_NULL | PTR_TO_BTF_ID | PTR_TRUSTED;
> info->btf = btf_vmlinux;
> - info->btf_id = task_struct_type_id;
> + info->btf_id = task_struct_btf_ids[0];
>
> return true;
> }
> @@ -5547,13 +5547,7 @@ static void bpf_scx_unreg(void *kdata, struct bpf_link *link)
>
> static int bpf_scx_init(struct btf *btf)
> {
> - s32 type_id;
> -
> - type_id = btf_find_by_name_kind(btf, "task_struct", BTF_KIND_STRUCT);
> - if (type_id < 0)
> - return -EINVAL;
> - task_struct_type = btf_type_by_id(btf, type_id);
> - task_struct_type_id = type_id;
> + task_struct_type = btf_type_by_id(btf, task_struct_btf_ids[0]);
Good optimization, but it's also unnecessary.
btf_id is already in btf_tracing_ids[BTF_TRACING_TYPE_TASK].
