Re: [PATCH RFC bpf-next v3 06/16] bpf/helpers: introduce bpf_timer_set_sleepable_cb() kfunc

[Eduard Zingerman]

On Wed, 2024-02-21 at 17:25 +0100, Benjamin Tissoires wrote:

[...]

> @@ -12120,6 +12137,16 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
>  		}
>  	}
>  
> +	if (is_async_callback_calling_kfunc(meta.func_id)) {

I think that it's better to check specific kfunc id here:

  meta.func_id == special_kfunc_list[KF_bpf_timer_set_sleepable_cb_impl]

In case if some new async callback calling kfunc would be added,
for which set_timer_callback_state() won't be correct.

> +		err = push_callback_call(env, insn, insn_idx, meta.subprogno,
> +					 set_timer_callback_state);
> +		if (err) {
> +			verbose(env, "kfunc %s#%d failed callback verification\n",
> +				func_name, meta.func_id);
> +			return err;
> +		}
> +	}
> +
>  	rcu_lock = is_kfunc_bpf_rcu_read_lock(&meta);
>  	rcu_unlock = is_kfunc_bpf_rcu_read_unlock(&meta);
>  
>