Re: [patch V2 20/29] tracing: Simplify stacktrace retrieval in histograms

[Tom Zanussi]

On Thu, 2019-04-18 at 09:40 -0400, Steven Rostedt wrote:
> [ Added Tom Zanussi ]
> 
> On Thu, 18 Apr 2019 10:41:39 +0200
> Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> 
> > The indirection through struct stack_trace is not necessary at all.
> > Use the
> > storage array based interface.
> > 
> > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> 
> Looks fine to me
> 
> Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> 
>  But...
> 
> Tom,
> 
> Can you review this too?

Looks good to me too!

Acked-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>


> 
> Patch series starts here:
> 
>   http://lkml.kernel.org/r/20190418084119.056416939@xxxxxxxxxxxxx
> 
> Thanks,
> 
> -- Steve
> 
> > ---
> >  kernel/trace/trace_events_hist.c |   12 +++---------
> >  1 file changed, 3 insertions(+), 9 deletions(-)
> > 
> > --- a/kernel/trace/trace_events_hist.c
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -5186,7 +5186,6 @@ static void event_hist_trigger(struct ev
> >  	u64 var_ref_vals[TRACING_MAP_VARS_MAX];
> >  	char compound_key[HIST_KEY_SIZE_MAX];
> >  	struct tracing_map_elt *elt = NULL;
> > -	struct stack_trace stacktrace;
> >  	struct hist_field *key_field;
> >  	u64 field_contents;
> >  	void *key = NULL;
> > @@ -5198,14 +5197,9 @@ static void event_hist_trigger(struct ev
> >  		key_field = hist_data->fields[i];
> >  
> >  		if (key_field->flags & HIST_FIELD_FL_STACKTRACE) {
> > -			stacktrace.max_entries = HIST_STACKTRACE_DEPTH;
> > -			stacktrace.entries = entries;
> > -			stacktrace.nr_entries = 0;
> > -			stacktrace.skip = HIST_STACKTRACE_SKIP;
> > -
> > -			memset(stacktrace.entries, 0,
> > HIST_STACKTRACE_SIZE);
> > -			save_stack_trace(&stacktrace);
> > -
> > +			memset(entries, 0, HIST_STACKTRACE_SIZE);
> > +			stack_trace_save(entries,
> > HIST_STACKTRACE_DEPTH,
> > +					 HIST_STACKTRACE_SKIP);
> >  			key = entries;
> >  		} else {
> >  			field_contents = key_field->fn(key_field, elt,
> > rbe, rec);
> > 
> 
>