linux-kernel - Re: [PATCH bpf-next v1 03/10] bpf: Verifier support for KF_IMPLICIT

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Message-ID: <18d9b15319bf8d71a3cd5b08239529505714dc96.camel@gmail.com>
Date: Tue, 13 Jan 2026 13:59:43 -0800
From: Eduard Zingerman <eddyz87@...il.com>
To: Ihor Solodrai <ihor.solodrai@...ux.dev>, Alexei Starovoitov
 <ast@...nel.org>,  Andrii Nakryiko <andrii@...nel.org>, Daniel Borkmann
 <daniel@...earbox.net>, Martin KaFai Lau <martin.lau@...ux.dev>
Cc: Mykyta Yatsenko <yatsenko@...a.com>, Tejun Heo <tj@...nel.org>, Alan
 Maguire <alan.maguire@...cle.com>, Benjamin Tissoires <bentiss@...nel.org>,
 Jiri Kosina	 <jikos@...nel.org>, bpf@...r.kernel.org,
 linux-kernel@...r.kernel.org, 	linux-input@...r.kernel.org,
 sched-ext@...ts.linux.dev
Subject: Re: [PATCH bpf-next v1 03/10] bpf: Verifier support for
 KF_IMPLICIT_ARGS

On Fri, 2026-01-09 at 10:48 -0800, Ihor Solodrai wrote:

[...]

> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -3271,6 +3271,38 @@ static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env, s16 offset)
>  	return btf_vmlinux ?: ERR_PTR(-ENOENT);
>  }
>  
> +#define KF_IMPL_SUFFIX "_impl"
> +
> +static const struct btf_type *find_kfunc_impl_proto(struct bpf_verifier_env *env,
> +						    struct btf *btf,
> +						    const char *func_name)
> +{
> +	char impl_name[KSYM_SYMBOL_LEN];

Oh, as we discussed already, this should use env->tmp_str_buf.

> +	const struct btf_type *func;
> +	s32 impl_id;
> +	int len;
> +
> +	len = snprintf(impl_name, sizeof(impl_name), "%s%s", func_name, KF_IMPL_SUFFIX);
> +	if (len < 0 || len >= sizeof(impl_name)) {
> +		verbose(env, "function name %s%s is too long\n", func_name, KF_IMPL_SUFFIX);
> +		return NULL;
> +	}

[...]