linux-kernel - [tip: sched/core] <linux/compiler_types.h>: Add the __signed_scalar

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Message-ID: <176569841006.498.2794868287250554578.tip-bot2@tip-bot2>
Date: Sun, 14 Dec 2025 07:46:50 -0000
From: "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Ingo Molnar <mingo@...nel.org>, Dietmar Eggemann <dietmar.eggemann@....com>,
 Juri Lelli <juri.lelli@...hat.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>, Mel Gorman <mgorman@...e.de>,
 Shrikanth Hegde <sshegde@...ux.ibm.com>,
 Valentin Schneider <vschneid@...hat.com>,
 Vincent Guittot <vincent.guittot@...aro.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: sched/core] <linux/compiler_types.h>: Add the
 __signed_scalar_typeof() helper

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     38a68b982dd0b10e3da943f100e034598326eafe
Gitweb:        https://git.kernel.org/tip/38a68b982dd0b10e3da943f100e034598326eafe
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Thu, 27 Nov 2025 16:39:44 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Sun, 14 Dec 2025 08:25:02 +01:00

<linux/compiler_types.h>: Add the __signed_scalar_typeof() helper

Define __signed_scalar_typeof() to declare a signed scalar type, leaving
non-scalar types unchanged.

To be used to clean up the scheduler load-balancing code a bit.

[ mingo: Split off this patch from the scheduler patch. ]

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Shrikanth Hegde <sshegde@...ux.ibm.com>
Cc: Valentin Schneider <vschneid@...hat.com>
Cc: Vincent Guittot <vincent.guittot@...aro.org>
Link: https://patch.msgid.link/20251127154725.413564507@infradead.org
---
 include/linux/compiler_types.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 1280693..280b4ac 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -586,6 +586,25 @@ struct ftrace_likely_data {
 			 __scalar_type_to_expr_cases(long long),	\
 			 default: (x)))
 
+/*
+ * __signed_scalar_typeof(x) - Declare a signed scalar type, leaving
+ *			       non-scalar types unchanged.
+ */
+
+#define __scalar_type_to_signed_cases(type)				\
+		unsigned type:	(signed type)0,				\
+		signed type:	(signed type)0
+
+#define __signed_scalar_typeof(x) typeof(				\
+		_Generic((x),						\
+			 char:	(signed char)0,				\
+			 __scalar_type_to_signed_cases(char),		\
+			 __scalar_type_to_signed_cases(short),		\
+			 __scalar_type_to_signed_cases(int),		\
+			 __scalar_type_to_signed_cases(long),		\
+			 __scalar_type_to_signed_cases(long long),	\
+			 default: (x)))
+
 /* Is this type a native word size -- useful for atomic operations */
 #define __native_word(t) \
 	(sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || \