[tip: sched/core] : Add the __signed_scalar_typeof() helper

tip-bot2 for Peter Zijlstra
2025-12-14T07:46:52Z

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@infradead.org>
AuthorDate: Thu, 27 Nov 2025 16:39:44 +01:00
Committer: Ingo Molnar <mingo@kernel.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@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.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) || \