Re: [PATCH bpf-next 2/2] selftests/bpf: Add test for css_task iter combining with cgroup iter

[Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>]

On Tue, Oct 31, 2023 at 4:38 AM Chuyi Zhou <zhouchuyi@xxxxxxxxxxxxx> wrote:
>
>
> So, maybe another possible solution is:
>
> diff --git a/kernel/bpf/cgroup_iter.c b/kernel/bpf/cgroup_iter.c
> index 209e5135f9fb..72a6778e3fba 100644
> --- a/kernel/bpf/cgroup_iter.c
> +++ b/kernel/bpf/cgroup_iter.c
> @@ -282,7 +282,7 @@ static struct bpf_iter_reg bpf_cgroup_reg_info = {
>          .ctx_arg_info_size      = 1,
>          .ctx_arg_info           = {
>                  { offsetof(struct bpf_iter__cgroup, cgroup),
> -                 PTR_TO_BTF_ID_OR_NULL },
> +                 PTR_TO_BTF_ID_OR_NULL | MEM_RCU },
>          },
>          .seq_info               = &cgroup_iter_seq_info,
>   };
> diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
> index 59e747938bdb..4fd3f734dffd 100644
> --- a/kernel/bpf/task_iter.c
> +++ b/kernel/bpf/task_iter.c
> @@ -706,7 +706,7 @@ static struct bpf_iter_reg task_reg_info = {
>          .ctx_arg_info_size      = 1,
>          .ctx_arg_info           = {
>                  { offsetof(struct bpf_iter__task, task),
> -                 PTR_TO_BTF_ID_OR_NULL },
> +                 PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },

Yep. That looks good.
bpf_cgroup_reg_info -> cgroup is probably PTR_TRUSTED too.
Not sure... why did you go with MEM_RCU there ?