linux-kernel - Re: [PATCH] bpf: add missing _

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Message-ID: <CAADnVQ+14yum8okMmjuqF5m5DafWo1fY1EuPj-QU_ykYbQ01uw@mail.gmail.com>
Date: Tue, 3 Feb 2026 08:34:02 -0800
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Arnd Bergmann <arnd@...nel.org>
Cc: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Andrii Nakryiko <andrii@...nel.org>, Song Liu <song@...nel.org>, KP Singh <kpsingh@...nel.org>, 
	Matt Bobrowski <mattbobrowski@...gle.com>, Steven Rostedt <rostedt@...dmis.org>, 
	Masami Hiramatsu <mhiramat@...nel.org>, Arnd Bergmann <arnd@...db.de>, 
	Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman <eddyz87@...il.com>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, 
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Mykyta Yatsenko <yatsenko@...a.com>, 
	Kumar Kartikeya Dwivedi <memxor@...il.com>, bpf <bpf@...r.kernel.org>, 
	LKML <linux-kernel@...r.kernel.org>, 
	linux-trace-kernel <linux-trace-kernel@...r.kernel.org>
Subject: Re: [PATCH] bpf: add missing __printf attributes

On Tue, Feb 3, 2026 at 8:27 AM Arnd Bergmann <arnd@...nel.org> wrote:
>
> From: Arnd Bergmann <arnd@...db.de>
>
> Some internal functions in bpf produce a warning when -Wsuggest-attribute=format
> is passed to the compiler, e.g. in 'make W=1':
>
> kernel/trace/bpf_trace.c: In function '____bpf_trace_printk':
> kernel/trace/bpf_trace.c:377:9: error: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Werror=suggest-attribute=format]
>   377 |         ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args);
>       |         ^~~
>
> The attribute here is useless since there are no callers from C code,
> but it helps to shut up the output anyway so we can eventually turn
> the warning option on by default.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

This was discussed and it's incorrect.
Commit 7bf819aa992f ("vsnprintf: Mark binary printing functions with
__printf() attribute")
should be reverted instead.

pw-bot: cr