linux-kernel - Re: [PATCH bpf-next v10 05/13] libbpf: Verify BTF Sorting

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Message-ID: <1970cb006e56500c8937e62a8a79042990fb152d.camel@gmail.com>
Date: Thu, 18 Dec 2025 11:38:12 -0800
From: Eduard Zingerman <eddyz87@...il.com>
To: Donglin Peng <dolinux.peng@...il.com>, ast@...nel.org, 
	andrii.nakryiko@...il.com
Cc: zhangxiaoqin@...omi.com, ihor.solodrai@...ux.dev, 
	linux-kernel@...r.kernel.org, bpf@...r.kernel.org, pengdonglin
	 <pengdonglin@...omi.com>, Alan Maguire <alan.maguire@...cle.com>
Subject: Re: [PATCH bpf-next v10 05/13] libbpf: Verify BTF Sorting

On Thu, 2025-12-18 at 19:30 +0800, Donglin Peng wrote:
> From: pengdonglin <pengdonglin@...omi.com>
> 
> This patch checks whether the BTF is sorted by name in ascending
> order. If sorted, binary search will be used when looking up types.
> 
> Cc: Eduard Zingerman <eddyz87@...il.com>
> Cc: Alexei Starovoitov <ast@...nel.org>
> Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
> Cc: Alan Maguire <alan.maguire@...cle.com>
> Cc: Ihor Solodrai <ihor.solodrai@...ux.dev>
> Cc: Xiaoqin Zhang <zhangxiaoqin@...omi.com>
> Signed-off-by: pengdonglin <pengdonglin@...omi.com>
> ---

(But could you please fix the btf_compare_type_names() prototype?)

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

>  tools/lib/bpf/btf.c | 41 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
> 
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index 2facb57d7e5f..c63d46b7d74b 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -899,6 +899,46 @@ int btf__resolve_type(const struct btf *btf, __u32 type_id)
>  	return type_id;
>  }
>  
> +/*
> + * Assuming that types are sorted by name in ascending order.
> + */
> +static int btf_compare_type_names(__u32 *a, __u32 *b, const struct btf *btf)

Nit: still no need for 'a' and 'b' to be pointers.

> +{
> +	struct btf_type *ta = btf_type_by_id(btf, *a);
> +	struct btf_type *tb = btf_type_by_id(btf, *b);
> +	const char *na, *nb;
> +
> +	na = btf__str_by_offset(btf, ta->name_off);
> +	nb = btf__str_by_offset(btf, tb->name_off);
> +	return strcmp(na, nb);
> +}

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