Re: [PATCH 1/7] perf tools: Track all user changed config bits

Leo Yan
2025-12-02T11:21:56Z

On Tue, Dec 02, 2025 at 10:40:49AM +0000, James Clark wrote:
>
>
> On 02/12/2025 10:15 am, Leo Yan wrote:
> > On Mon, Dec 01, 2025 at 04:41:04PM +0000, Coresight ML wrote:
> >
> > [...]
> >
> > > +#define ADD_CONFIG_CHG(format_type, term_type, new_term) \
> > > +{ \
> > > + struct parse_events_term *term; \
> > > + u64 bits = 0; \
> > > + int type; \
> > > + \
> > > + list_for_each_entry(term, &head_config->terms, list) { \
> > > + if (term->type_term == PARSE_EVENTS__TERM_TYPE_USER) { \
> > > + type = perf_pmu__format_type(pmu, term->config);\
> > > + if (type != format_type) \
> > > + continue; \
> > > + bits |= perf_pmu__format_bits(pmu, term->config); \
> > > + } else if (term->type_term == term_type) { \
> > > + bits = ~(u64)0; \
> > > + } \
> > > + } \
> > > + \
> > > + if (bits) \
> > > + ADD_CONFIG_TERM_VAL(new_term, cfg_chg, bits, false); \
> > > + return 0; \
> >
> > Nitpick: "return 0" is not needed here. Otherwise:
> >
> > Reviewed-by: Leo Yan <leo.yan@arm.com>
>
> I think it's worse than not needed, it makes it stop collecting the changes
> after the first one.

Just curious how this can happen.

foo()
{
{
chunk 1;
}

{
chunk 2;
}
}

Seem to me, if without "return 0" in chunk 1, it still can continue to
run chunk 2, no?

> It was annoying that this had to be a macro instead of a function because
> ADD_CONFIG_TERM_VAL constructs the #define name of the first argument.
>
> It's probably worth putting in some effort to make ADD_CONFIG_CHG() a
> function to avoid problems like this and maybe add a test.

This would be fine for me.

Thanks,
Leo