[PATCH 2/2 v2] tracing: Fix sparse warning with is_signed_type() macro

[Steven Rostedt]

From: Steven Rostedt <srostedt@xxxxxxxxxx>

Sparse complains when is_signed_type() is used on a pointer.
This macro is needed for the format output used for ftrace
and perf, to know if a binary field is a signed type or not.
The is_signed_type() macro is used against all fields that are
recorded by events to automate the operation.

The problem sparse has is with the current way is_signed_type()
works:

  ((type)-1 < 0)

If "type" is a poiner, than sparse does not like it being compared
to an integer (zero). The simple fix is to just give zero the
same type. The runtime result stays the same.

Reported-by: Robert Jarzmik <robert.jarzmik@xxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 include/linux/ftrace_event.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 642928c..cc87955 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -266,7 +266,7 @@ extern int trace_define_field(struct ftrace_event_call *call, const char *type,
 extern int trace_add_event_call(struct ftrace_event_call *call);
 extern void trace_remove_event_call(struct ftrace_event_call *call);
 
-#define is_signed_type(type)	(((type)(-1)) < 0)
+#define is_signed_type(type)	(((type)(-1)) < (type)0)
 
 int trace_set_clr_event(const char *system, const char *event, int set);
 
-- 
1.7.10.4

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