Re: ftrace histogram sorting broken on BE architecures

Steven Rostedt
2019-12-11T16:10:05Z

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); \
}