On Mon, Mar 12, 2018 at 07:52:45PM -0400, Steven Rostedt wrote:
> On Mon, 12 Mar 2018 19:54:14 +0100
> Jiri Olsa <jo...@redhat.com> wrote:
> 
> > On Mon, Mar 12, 2018 at 02:40:01PM -0400, Steven Rostedt wrote:
> > > On Mon, 12 Mar 2018 16:10:17 +0100
> > > Jiri Olsa <jo...@redhat.com> wrote:
> > >   
> > > > got it crashed when clearing the filter via 'echo > filter'  
> > > 
> > > Awesome. I'll go and test this out. Thanks!
> > > 
> > > Hmm, could you pull my tree and test my branch: ftrace/core. I may have
> > > already fixed this but haven't posted the latest (which I'll do before
> > > pushing to next).  
> > 
> > I couldn't apply your patches from mailbox so I used your ftrace/core 
> > already
> >
> 
> Jiri, If you apply the below, does it fix it for you?

yes, the crash is gone and I can set filter ftrace/function,
but I'm still having some issues put that filter through perf

  # perf record -e ftrace:function --filter "ip == 0xffffffffa41e8490" ls

but I might be just missing something.. it's been a while ;-) I'm looking to 
that

jirka


> 
> -- Steve
> 
> diff --git a/kernel/trace/trace_events_filter.c 
> b/kernel/trace/trace_events_filter.c
> index a5a131ec3c9c..4099e141188c 100644
> --- a/kernel/trace/trace_events_filter.c
> +++ b/kernel/trace/trace_events_filter.c
> @@ -1498,11 +1498,14 @@ static int process_preds(struct trace_event_call 
> *call,
>               return ret;
>       }
>  
> -     prog = predicate_parse(filter_string, nr_parens, nr_preds,
> +     if (!nr_preds) {
> +             prog = NULL;
> +     } else {
> +             prog = predicate_parse(filter_string, nr_parens, nr_preds,
>                              parse_pred, call, pe);
> -     if (IS_ERR(prog))
> -             return PTR_ERR(prog);
> -
> +             if (IS_ERR(prog))
> +                     return PTR_ERR(prog);
> +     }
>       rcu_assign_pointer(filter->prog, prog);
>       return 0;
>  }

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