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

Steven Rostedt
2019-04-18T13:40:14Z

[ Added Tom Zanussi ]

On Thu, 18 Apr 2019 10:41:39 +0200
Thomas Gleixner <tglx@linutronix.de> wrote:

> The indirection through struct stack_trace is not necessary at all. Use the
> storage array based interface.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Steven Rostedt <rostedt@goodmis.org>

Looks fine to me

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

But...

Tom,

Can you review this too?

Patch series starts here:

http://lkml.kernel.org/r/20190418084119.056416939@linutronix.de

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);
>