Re: [PATCH v4 1/2] perf parse: Refactor struct perf_evsel_config_term

Leo Yan
2020-01-13T15:21:14Z

On Fri, Jan 10, 2020 at 04:04:10PM +0100, Jiri Olsa wrote:
> On Thu, Jan 09, 2020 at 09:34:24AM -0700, Mathieu Poirier wrote:
>
> SNIP
>
> >
> > If we are to deal with all flields of the union, I think it should be as below:
> >
> > union {
> > bool cfg_bool;
> > int cfg_int;
> > unsigned long cfg_ulong;
> > u32 cfg_u32;
> > char *cfg_str;
> > } val;
> >
> > But just dealing with the "char *" as below would also be fine with me:
> >
> > union {
> > u64 period;
> > u64 freq;
> > bool time;
> > u64 stack_user;
> > int max_stack;
> > bool inherit;
> > bool overwrite;
> > unsigned long max_events;
> > bool percore;
> > bool aux_output;
> > u32 aux_sample_size;
> > u64 cfg_chg;
> > u64 num;
> > char *str;
> > } val;
> >
> > >
> > > struct perf_evsel_config_term {
> > > struct list_head list;
> > > enum evsel_term_type type;
> > > union {
> > > u64 period;
> > > u64 freq;
> > > bool time;
> > > char *callgraph;
> > > char *drv_cfg;
> > > u64 stack_user;
> > > int max_stack;
> > > bool inherit;
> > > bool overwrite;
> > > char *branch;
> > > unsigned long max_events;
> > > bool percore;
> > > bool aux_output;
> > > u32 aux_sample_size;
> > > u64 cfg_chg;
> > > + u64 num;
> > > + char *str;
> > > } val;
> > > bool weak;
> > > };
> > >
> > > > I will let Jiri make the
> > > > final call but if we are to proceed this way I think we should have a
> > > > member per type to avoid casting issues.
> > >
> > > Yeah, let's see what's Jiri thinking.
> > >
> > > Just note, with this change, I don't see any casting warning or errors
> > > when built perf on arm64/arm32.
> >
> > At this time you may not, but they will happen and it will be very hard to
> > debug.
>
> hi,
> sry for late reply..
>
> I think ;-) we should either add all different types to the union
> or just add 'str' pointer to handle strings correctly.. which seems
> better, because it's less changes and there's no real issue that
> would need that other bigger change

Thanks for the suggestion, Jiri.

Have sent out patch v5 with following the ideas.

Thanks,
Leo Yan