On Tue, Feb 3, 2026 at 8:58 AM Arnd Bergmann <[email protected]> wrote:
>
> On Tue, Feb 3, 2026, at 17:34, Alexei Starovoitov wrote:
> > On Tue, Feb 3, 2026 at 8:27 AM Arnd Bergmann <[email protected]> wrote:
> >>
> >> From: Arnd Bergmann <[email protected]>
> >>
> >> 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 <[email protected]>
> >
> > 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,
because it's not a printf format. There are no varags here.
gnu_printf attribute takes two arguments:
format (archetype, string-index, first-to-check)
Also
"GCC requires a function with the 'format' attribute to be variadic"
> > 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.
Somebody needs to root cause it and fix it properly.
Adding more incorrect annotation is not a solution.
