Re: [PATCH] vsnprintf: drop __printf() attributes on binary printing functions

[Andy Shevchenko]

On Wed, Feb 04, 2026 at 02:26:23PM +0100, Arnd Bergmann wrote:

> The printf() format attributes are applied inconsistently for the binary
> printf helpers, which causes warnings for the bpf_trace code using
> them from functions that pass down format strings:
> 
>     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);
>           |         ^~~
> 
> This can be addressed either by annotating all five callers in bpf code,
> or by removing the annotations on the callees that were added by Andy
> Shevchenko last year.
> 
> As Alexei Starovoitov points out, there are no callers in C code that
> would benefit from the __printf attributes, the only users are in BPF
> code or in the do_trace_printk() helper that already checks the arguments.
> 
> Drop all three of these annotations, reverting the earlierl commits that
> added these, in order to get a clean build with -Wsuggest-attribute=format.

Acked-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

-- 
With Best Regards,
Andy Shevchenko