Subject: [PATCH v2 01/27 5.10.y] overflow, tracing: Define the is_signed_type() macro once

From: Eliav Farber <[email-masked]>
Date: Fri, 17 Oct 2025 09:04:53 +0000

From: Bart Van Assche <[email-masked]>

[ Upstream commit 92d23c6e94157739b997cacce151586a0d07bb8a ]

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 Torvalds, 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. See also:
https://lore.kernel.org/all/CAHk-=[email-masked]/
https://lore.kernel.org/all/CAHk-=[email-masked]/

Cc: Andrew Morton <[email-masked]>
Cc: Arnd Bergmann <[email-masked]>
Cc: Dan Williams <[email-masked]>
Cc: Eric Dumazet <[email-masked]>
Cc: Ingo Molnar <[email-masked]>
Cc: Isabella Basso <[email-masked]>
Cc: "Jason A. Donenfeld" <[email-masked]>
Cc: Josh Poimboeuf <[email-masked]>
Cc: Luc Van Oostenryck <[email-masked]>
Cc: Masami Hiramatsu <[email-masked]>
Cc: Nathan Chancellor <[email-masked]>
Cc: Peter Zijlstra <[email-masked]>
Cc: Rasmus Villemoes <[email-masked]>
Cc: Sander Vanheule <[email-masked]>
Cc: Steven Rostedt <[email-masked]>
Cc: Vlastimil Babka <[email-masked]>
Cc: Yury Norov <[email-masked]>
Signed-off-by: Bart Van Assche <[email-masked]>
Signed-off-by: Kees Cook <[email-masked]>
Link: https://lore.kernel.org/r/[email-masked]
Signed-off-by: Eliav Farber <[email-masked]>
---
 include/linux/compiler.h     | 6 ++++++
 include/linux/overflow.h     | 1 -
 include/linux/trace_events.h | 2 --
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index bbd74420fa21..004a030d5ad2 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -245,6 +245,12 @@ 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.
diff --git a/include/linux/overflow.h b/include/linux/overflow.h
index 73bc67ec2136..e6bf14f462e9 100644
--- a/include/linux/overflow.h
+++ b/include/linux/overflow.h
@@ -29,7 +29,6 @@
  * 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))
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 5af2acb9fb7d..0c8c3cf36f96 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -700,8 +700,6 @@ 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,
-- 
2.47.3