Re: [PATCH v2 7/7] tools/testing/selftests/bpf: replace open-coded 16 with TASK_COMM_LEN

[Yafang Shao]

On Tue, Nov 30, 2021 at 1:30 AM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> On Mon, 29 Nov 2021 11:13:31 +0100
> Sven Schnelle <svens@xxxxxxxxxxxxx> wrote:
>
>
> > This breaks the trigger-field-variable-support.tc from the ftrace test
> > suite at least on s390:
> >
> > echo 'hist:keys=next_comm:wakeup_lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid,sched.sched_waking.prio,next_comm) if next_comm=="ping"'
> > linux/tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-field-variable-support.tc: line 15: echo: write error: Invalid argument
> >
> > I added a debugging line into check_synth_field():
> >
> > [   44.091037] field->size 16, hist_field->size 16, field->is_signed 1, hist_field->is_signed 0
> >
> > Note the difference in the signed field.
>
> That should not break on strings.
>
> Does this fix it (if you keep the patch)?
>
> -- Steve
>
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 9555b8e1d1e3..319f9c8ca7e7 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -3757,7 +3757,7 @@ static int check_synth_field(struct synth_event *event,
>
>         if (strcmp(field->type, hist_field->type) != 0) {
>                 if (field->size != hist_field->size ||
> -                   field->is_signed != hist_field->is_signed)
> +                   (!field->is_string && field->is_signed != hist_field->is_signed))
>                         return -EINVAL;
>         }
>

Many thanks for the quick fix!
It seems this fix should be ahead of patch #7.
I will send v3 which contains your fix.

-- 
Thanks
Yafang