Re: [PATCH] btf: Simplify BTF logic with use of __free(btf_put)

Alexei Starovoitov
2025-08-01T15:12:21Z

On Fri, Aug 1, 2025 at 8:06 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Fri, 1 Aug 2025 08:02:24 -0700
> Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:
>
> > > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> > > index 1d2cf898e21e..480657912c96 100644
> > > --- a/kernel/bpf/btf.c
> > > +++ b/kernel/bpf/btf.c
> > > @@ -3788,7 +3788,7 @@ static int btf_parse_kptr(const struct btf *btf, struct btf_field *field,
> > > /* If a matching btf type is found in kernel or module BTFs, kptr_ref
> > > * is that BTF, otherwise it's program BTF
> > > */
> > > - struct btf *kptr_btf;
> > > + struct btf *kptr_btf __free(btf_put) = NULL;
> >
> > Sorry I hate this __free() style.
> > It's not a simplification, but an obfuscation of code and logic.
>
> Well, it's becoming more common. But you are in control of this, so it's
> your decision. I wanted this just to get rid of the gotos in my code.

You can use it in kernel/trace/trace_output.c, of course,
but I really think it's a step back in maintainability.
All this cleanup.h is not a silver bullet. It needs to be used sparingly.