Re: ftrace histogram sorting broken on BE architecures

Tom Zanussi
2019-12-12T19:17:24Z

On Wed, 2019-12-11 at 11:09 -0500, Steven Rostedt wrote:
> On Wed, 11 Dec 2019 10:35:57 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
>
> > > Any thoughts on how to fix this? I'm not sure whether i fully
> > > understand the
> > > ftrace maps... ;-)
> >
> > Your analysis makes sense. I'll take a deeper look at it.
>
> Sven,
>
> Does this patch fix it for you?
>
> Tom,
>
> Correct me if I'm wrong, from what I can tell, all sums and keys are
> u64 unless they are a string. Thus, I believe this patch should not
> have any issues.
>
> -- Steve
>
> diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
> index 9a1c22310323..9e31bfc818ff 100644
> --- a/kernel/trace/tracing_map.c
> +++ b/kernel/trace/tracing_map.c
> @@ -148,8 +148,8 @@ static int tracing_map_cmp_atomic64(void *val_a,
> void *val_b)
> #define DEFINE_TRACING_MAP_CMP_FN(type)
> \
> static int tracing_map_cmp_##type(void *val_a, void *val_b)
> \
> {
> \
> - type a = *(type *)val_a;
> \
> - type b = *(type *)val_b;
> \
> + type a = (type)(*(u64 *)val_a);
> \
> + type b = (type)(*(u64 *)val_b);
> \
>
> \
> return (a > b) ? 1 : ((a < b) ? -1 : 0);
> \
> }

Acked-by: Tom Zanussi <zanussi@kernel.org>