netdev - Re: [PATCH bpf-next 08/11] libbpf: support BTF dedup of split BTFs

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Date:   Mon, 2 Nov 2020 21:10:03 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Andrii Nakryiko <andrii@...nel.org>
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org, ast@...com,
        daniel@...earbox.net, kernel-team@...com
Subject: Re: [PATCH bpf-next 08/11] libbpf: support BTF dedup of split BTFs

On Wed, Oct 28, 2020 at 05:58:59PM -0700, Andrii Nakryiko wrote:
> @@ -2942,6 +2948,13 @@ struct btf_dedup {
>  	__u32 *hypot_list;
>  	size_t hypot_cnt;
>  	size_t hypot_cap;
> +	/* Whether hypothethical mapping, if successful, would need to adjust
> +	 * already canonicalized types (due to a new forward declaration to
> +	 * concrete type resolution). In such case, during split BTF dedup
> +	 * candidate type would still be considered as different, because base
> +	 * BTF is considered to be immutable.
> +	 */
> +	bool hypot_adjust_canon;

why one flag per dedup session is enough?
Don't you have a case where some fwd are pointing to base btf and shouldn't
be adjusted while some are in split btf and should be?
It seems when this flag is set to true it will miss fwd in split btf?