On Wed, 19 Oct 2016 15:06:34 -0300
Arnaldo Carvalho de Melo <a...@kernel.org> wrote:
> Em Wed, Oct 19, 2016 at 03:05:48PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Wed, Oct 19, 2016 at 02:48:45PM -0300, Arnaldo Carvalho de Melo
> > escreveu:
> > > Em Tue, Oct 18, 2016 at 11:29:53AM -0400, Steven Rostedt escreveu:
> > > > On Tue, 18 Oct 2016 11:01:09 +0900
> > > > Namhyung Kim <namhy...@kernel.org> wrote:
> > > >
> > > > > Hi Honggyu,
> > > > >
> > > > > You need to CC relevant maintainers when you send patches to LKML.
> > > > > For the libtraceevent, they are Arnaldo and Steven. You can use
> > > > > scripts/get_maintainer.pl for this job later. In addition running
> > > > > scripts/checkpatch.pl before sending patches is a good habit.
> > > > >
> > > > > Arnaldo and Steve,
> > > > >
> > > > > This is from uftrace building libtraceevent with the optimization flag
> > > > > and we want to fix the upstream as well.
> > > > >
> > > >
> > > > Acked-by: Steven Rostedt <rost...@goodmis.org>
> > >
> > > So right after applying this patch I get these new warnings,
> > > investigating...
> >
> > Some are the compiler not grokking logic where the compiler gets
> > confused with logic that tests one variable to use another and thinks it
> > is using garbage (uninitialized stuff), I tried to follow the logic and
> > I think it got slightly more confused than me, as I _think_ its not a
> > problem, but the one on the case entry for
> >
> > OLD_RINGBUF_TYPE_TIME_EXTEND
> >
> > in old_update_pointers() looks like a bug, unless some macro magic is
> > taking place that updates that 'lenght' variable.
> >
> > Rostedt, that -O2 unleashed some warnings, please check, I'll defer
> > applying those patches till it doesn't show these warnings, i.e. till
> > other patches fixing these issues or simply silencing the compiler with
> > a harmless init gets submitted,
>
> Ah, the patch I had so far shutting off most of this is:
>
>
> diff --git a/tools/lib/traceevent/event-parse.c
> b/tools/lib/traceevent/event-parse.c
> index 664c90c8e22b..449056e96fe6 100644
> --- a/tools/lib/traceevent/event-parse.c
> +++ b/tools/lib/traceevent/event-parse.c
> @@ -3490,7 +3490,7 @@ struct event_format *
> pevent_find_event_by_name(struct pevent *pevent,
> const char *sys, const char *name)
> {
> - struct event_format *event;
> + struct event_format *event = NULL;
> int i;
Grumble. This is just bad gcc. I mean we have:
for (i = 0; i < pevent->nr_events; i++) {
event = pevent->events[i];
if (i == pevent->nr_events)
event = NULL;
How the hell can event be uninitialized after that?
>
> if (pevent->last_event &&
> @@ -4843,7 +4843,7 @@ static void pretty_print(struct trace_seq *s, void
> *data, int size, struct event
> char format[32];
> int show_func;
> int len_as_arg;
> - int len_arg;
> + int len_arg = 0;
Again, silly gcc.
> int len;
> int ls;
>
> @@ -5102,8 +5102,8 @@ void pevent_data_lat_fmt(struct pevent *pevent,
> static int migrate_disable_exists;
> unsigned int lat_flags;
> unsigned int pc;
> - int lock_depth;
> - int migrate_disable;
> + int lock_depth = 0;
> + int migrate_disable = 0;
> int hardirq;
> int softirq;
> void *data = record->data;
silly gcc.
Fine, add these.
-- Steve
