linux-kernel - [PATCH 4/4 5.10.y] tracing: Define the is_signed

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Message-ID: <20250912125606.13262-5-farbere@amazon.com>
Date: Fri, 12 Sep 2025 12:56:05 +0000
From: Eliav Farber <farbere@...zon.com>
To: <luc.vanoostenryck@...il.com>, <rostedt@...dmis.org>, <mingo@...hat.com>,
	<natechancellor@...il.com>, <ndesaulniers@...gle.com>,
	<keescook@...omium.org>, <sashal@...nel.org>, <akpm@...ux-foundation.org>,
	<ojeda@...nel.org>, <elver@...gle.com>, <gregkh@...uxfoundation.org>,
	<kbusch@...nel.org>, <sj@...nel.org>, <bvanassche@....org>,
	<leon@...nel.org>, <jgg@...pe.ca>, <linux-kernel@...r.kernel.org>,
	<linux-sparse@...r.kernel.org>, <clang-built-linux@...glegroups.com>,
	<stable@...r.kernel.org>
CC: <jonnyc@...zon.com>, <farbere@...zon.com>, Rasmus Villemoes
	<linux@...musvillemoes.dk>
Subject: [PATCH 4/4 5.10.y] tracing: Define the is_signed_type() macro once

From: Bart Van Assche <bvanassche@....org>

commit a49a64b5bf195381c09202c524f0f84b5f3e816f upstream.

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 <linux@...musvillemoes.dk>
Cc: Steven Rostedt <rostedt@...dmis.org>
Acked-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Bart Van Assche <bvanassche@....org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
(cherry picked from commit a49a64b5bf195381c09202c524f0f84b5f3e816f)
Signed-off-by: SeongJae Park <sj@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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