Re: [RFC PATCH v1 04/14] bpf: Refactor check_pseudo_btf_id's BTF reference bump

[Eduard Zingerman <eddyz87@gmail.com>]

On Thu, 2024-02-01 at 04:20 +0000, Kumar Kartikeya Dwivedi wrote:
> Refactor check_pseudo_btf_id's code which adds a new BTF reference to
> the used_btfs into a separate helper function called add_used_btfs. This
> will be later useful in exception frame generation to take BTF
> references with their modules, so that we can keep the modules alive
> whose functions may be required to unwind a given BPF program when it
> eventually throws an exception.

[...]

> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

[...]

> +static int add_used_btf(struct bpf_verifier_env *env, struct btf *btf)

[...]

> +	if (env->used_btf_cnt >= MAX_USED_BTFS) {
> +		err = -E2BIG;
> +		goto err;

Nit: could be "return -E2BIG"

> +	}
> +
> +	btf_mod = &env->used_btfs[env->used_btf_cnt];
> +	btf_mod->btf = btf;
> +	btf_mod->module = NULL;
> +
> +	/* if we reference variables from kernel module, bump its refcount */
> +	if (btf_is_module(btf)) {
> +		btf_mod->module = btf_try_get_module(btf);
> +		if (!btf_mod->module) {
> +			err = -ENXIO;
> +			goto err;

Nit: could be "return -ENXIO"

> +		}
> +	}
> +	env->used_btf_cnt++;
> +	return 0;
> +err:
> +	return err;
> +}
> +