Re: [PATCH] bpf: add missing __printf attributes

["Arnd Bergmann" <arnd@arndb.de>]

On Tue, Feb 3, 2026, at 17:34, Alexei Starovoitov wrote:
> On Tue, Feb 3, 2026 at 8:27 AM Arnd Bergmann <arnd@kernel.org> wrote:
>>
>> From: Arnd Bergmann <arnd@arndb.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@arndb.de>
>
> This was discussed and it's incorrect.

Do you have a reference to why it's incorrect?  It seems harmless
and gives me a clean kernel build in combination with a handful
of other fixes after enabling the option by default, but I assume
I'm missing something,

> Commit 7bf819aa992f ("vsnprintf: Mark binary printing functions with
> __printf() attribute") should be reverted instead.

Reverting that one would appear to introduce warnings elsewhere,
so that would not be a complete fix either.

      Arnd