Re: [PATCH] tracing/synthetic: Print out u64 values properly

[Tero Kristo]

Hi Masami,

On 15/09/2023 09:01, Masami Hiramatsu (Google) wrote:
> Hi Tero,
>
> On Mon, 11 Sep 2023 17:17:04 +0300
> Tero Kristo <tero.kristo@xxxxxxxxxxxxxxx> wrote:
>
> > The synth traces incorrectly print pointer to the synthetic event values
> > instead of the actual value when using u64 type. Fix by addressing the
> > contents of the union properly.
> Thanks for pointing it out.
> But I would like to see a new "case 8:" print code instead of changing
> "default". Can you keep the default as it is and add "case 8:" case there?

Are you sure about that? I think keeping the default as is would just 
print out a useless pointer value to the synth event itself (which is 
what happened with u64 type.)

Anyways, that requires a new patch to be created on top as this has hit 
the mainline as a fix already.

-Tero


> Thanks,
>
> > Fixes: ddeea494a16f ("tracing/synthetic: Use union instead of casts")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Tero Kristo <tero.kristo@xxxxxxxxxxxxxxx>
> > ---
> >   kernel/trace/trace_events_synth.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
> > index 7fff8235075f..070365959c0a 100644
> > --- a/kernel/trace/trace_events_synth.c
> > +++ b/kernel/trace/trace_events_synth.c
> > @@ -337,7 +337,7 @@ static void print_synth_event_num_val(struct trace_seq *s,
> >   		break;
> >   
> >   	default:
> > -		trace_seq_printf(s, print_fmt, name, val, space);
> > +		trace_seq_printf(s, print_fmt, name, val->as_u64, space);
> >   		break;
> >   	}
> >   }
> > --
> > 2.40.1