tracing: Define the is_signed_type() macro once

There are two definitions of the is_signed_type() macro: one in
<linux/overflow.h> and a second definition in <linux/trace_events.h>.

As suggested by Linus, move the definition of the is_signed_type() macro
into the <linux/compiler.h> header file.  Change the definition of the
is_signed_type() macro to make sure that it does not trigger any sparse
warnings with future versions of sparse for bitwise types.

Link: https://lore.kernel.org/all/CAHk-=whjH6p+qzwUdx5SOVVHjS3WvzJQr6mDUwhEyTf6pJWzaQ@mail.gmail.com/
Link: https://lore.kernel.org/all/CAHk-=wjQGnVfb4jehFR0XyZikdQvCZouE96xR_nnf5kqaM5qqQ@mail.gmail.com/
Cc: Rasmus Villemoes <[email protected]>
Cc: Steven Rostedt <[email protected]>
Acked-by: Kees Cook <[email protected]>
Signed-off-by: Bart Van Assche <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: bvanassche

include/linux/compiler.h

@@ -239,6 +239,12 @@ static inline void *offset_to_ptr(const int *off)
 /* &a[0] degrades to a pointer: a different type from an array */
 #define __must_be_array(a)	BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
 
+/*
+ * Whether 'type' is a signed type or an unsigned type. Supports scalar types,
+ * bool and also pointer types.
+ */
+#define is_signed_type(type) (((type)(-1)) < (__force type)1)
+
 /*
  * This is needed in functions which generate the stack canary, see
  * arch/x86/kernel/smpboot.c::start_secondary() for an example.

include/linux/overflow.h

@@ -30,7 +30,6 @@
  * https://mail-index.netbsd.org/tech-misc/2007/02/05/0000.html -
  * credit to Christian Biere.
  */
-#define is_signed_type(type)       (((type)(-1)) < (type)1)
 #define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type)))
 #define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
 #define type_min(T) ((T)((T)-type_max(T)-(T)1))

include/linux/trace_events.h

@@ -814,8 +814,6 @@ extern int trace_add_event_call(struct trace_event_call *call);
 extern int trace_remove_event_call(struct trace_event_call *call);
 extern int trace_event_get_offsets(struct trace_event_call *call);
 
-#define is_signed_type(type)	(((type)(-1)) < (type)1)
-
 int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
 int trace_set_clr_event(const char *system, const char *event, int set);
 int trace_array_set_clr_event(struct trace_array *tr, const char *system,