This is a note to let you know that I've just added the patch titled
minmax.h: reduce the #define expansion of min(), max() and clamp()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
minmax.h-reduce-the-define-expansion-of-min-max-and-clamp.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From [email protected] Fri Oct 17 11:12:54 2025
From: Eliav Farber <[email protected]>
Date: Fri, 17 Oct 2025 09:05:15 +0000
Subject: minmax.h: reduce the #define expansion of min(), max() and clamp()
To: <[email protected]>, <[email protected]>,
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Cc: Arnd Bergmann <[email protected]>, Christoph Hellwig <[email protected]>,
Dan Carpenter <[email protected]>, Jens Axboe <[email protected]>, Lorenzo
Stoakes <[email protected]>, Mateusz Guzik <[email protected]>, Pedro
Falcato <[email protected]>
Message-ID: <[email protected]>
From: David Laight <[email protected]>
[ Upstream commit b280bb27a9f7c91ddab730e1ad91a9c18a051f41 ]
Since the test for signed values being non-negative only relies on
__builtion_constant_p() (not is_constexpr()) it can use the 'ux' variable
instead of the caller supplied expression. This means that the #define
parameters are only expanded twice. Once in the code and once quoted in
the error message.
Link:
https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Laight <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Dan Carpenter <[email protected]>
Cc: Jason A. Donenfeld <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Mateusz Guzik <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Pedro Falcato <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Eliav Farber <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
include/linux/minmax.h | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -46,10 +46,10 @@
* comparison, and these expressions only need to be careful to not cause
* warnings for pointer use.
*/
-#define __signed_type_use(x, ux) (2 + __is_nonneg(x, ux))
-#define __unsigned_type_use(x, ux) (1 + 2 * (sizeof(ux) < 4))
-#define __sign_use(x, ux) (is_signed_type(typeof(ux)) ? \
- __signed_type_use(x, ux) : __unsigned_type_use(x, ux))
+#define __signed_type_use(ux) (2 + __is_nonneg(ux))
+#define __unsigned_type_use(ux) (1 + 2 * (sizeof(ux) < 4))
+#define __sign_use(ux) (is_signed_type(typeof(ux)) ? \
+ __signed_type_use(ux) : __unsigned_type_use(ux))
/*
* Check whether a signed value is always non-negative.
@@ -71,13 +71,13 @@
#else
#define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux) > 4, 1LL,
1L))
#endif
-#define __is_nonneg(x, ux) statically_true((__signed_type(ux))(x) >= 0)
+#define __is_nonneg(ux) statically_true((__signed_type(ux))(ux) >= 0)
-#define __types_ok(x, y, ux, uy) \
- (__sign_use(x, ux) & __sign_use(y, uy))
+#define __types_ok(ux, uy) \
+ (__sign_use(ux) & __sign_use(uy))
-#define __types_ok3(x, y, z, ux, uy, uz) \
- (__sign_use(x, ux) & __sign_use(y, uy) & __sign_use(z, uz))
+#define __types_ok3(ux, uy, uz) \
+ (__sign_use(ux) & __sign_use(uy) & __sign_use(uz))
#define __cmp_op_min <
#define __cmp_op_max >
@@ -92,7 +92,7 @@
#define __careful_cmp_once(op, x, y, ux, uy) ({ \
__auto_type ux = (x); __auto_type uy = (y); \
- BUILD_BUG_ON_MSG(!__types_ok(x, y, ux, uy), \
+ BUILD_BUG_ON_MSG(!__types_ok(ux, uy), \
#op"("#x", "#y") signedness error"); \
__cmp(op, ux, uy); })
@@ -109,7 +109,7 @@
static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)),
\
(lo) <= (hi), true),
\
"clamp() low limit " #lo " greater than high limit " #hi);
\
- BUILD_BUG_ON_MSG(!__types_ok3(val, lo, hi, uval, ulo, uhi),
\
+ BUILD_BUG_ON_MSG(!__types_ok3(uval, ulo, uhi),
\
"clamp("#val", "#lo", "#hi") signedness error");
\
__clamp(uval, ulo, uhi); })
@@ -149,7 +149,7 @@
#define __careful_op3(op, x, y, z, ux, uy, uz) ({ \
__auto_type ux = (x); __auto_type uy = (y);__auto_type uz = (z);\
- BUILD_BUG_ON_MSG(!__types_ok3(x, y, z, ux, uy, uz), \
+ BUILD_BUG_ON_MSG(!__types_ok3(ux, uy, uz), \
#op"3("#x", "#y", "#z") signedness error"); \
__cmp(op, ux, __cmp(op, uy, uz)); })
Patches currently in stable-queue which might be from [email protected] are
queue-5.10/minmax-allow-comparisons-of-int-against-unsigned-char-short.patch
queue-5.10/minmax-add-a-few-more-min_t-max_t-users.patch
queue-5.10/minmax-improve-macro-expansion-and-type-checking.patch
queue-5.10/minmax-fix-indentation-of-__cmp_once-and-__clamp_once.patch
queue-5.10/minmax.h-simplify-the-variants-of-clamp.patch
queue-5.10/minmax-add-in_range-macro.patch
queue-5.10/minmax.h-move-all-the-clamp-definitions-after-the-min-max-ones.patch
queue-5.10/minmax-allow-min-max-clamp-if-the-arguments-have-the-same-signedness.patch
queue-5.10/minmax-don-t-use-max-in-situations-that-want-a-c-constant-expression.patch
queue-5.10/minmax.h-remove-some-defines-that-are-only-expanded-once.patch
queue-5.10/minmax.h-use-build_bug_on_msg-for-the-lo-hi-test-in-clamp.patch
queue-5.10/minmax-simplify-min-max-clamp-implementation.patch
queue-5.10/minmax-deduplicate-__unconst_integer_typeof.patch
queue-5.10/minmax-simplify-and-clarify-min_t-max_t-implementation.patch
queue-5.10/minmax.h-add-whitespace-around-operators-and-after-commas.patch
queue-5.10/minmax-sanity-check-constant-bounds-when-clamping.patch
queue-5.10/minmax-avoid-overly-complicated-constant-expressions-in-vm-code.patch
queue-5.10/minmax-make-generic-min-and-max-macros-available-everywhere.patch
queue-5.10/minmax-fix-up-min3-and-max3-too.patch
queue-5.10/minmax.h-reduce-the-define-expansion-of-min-max-and-clamp.patch
queue-5.10/minmax-fix-header-inclusions.patch
queue-5.10/minmax-introduce-min-max-_array.patch
queue-5.10/btrfs-remove-duplicated-in_range-macro.patch
queue-5.10/overflow-tracing-define-the-is_signed_type-macro-once.patch
queue-5.10/minmax-relax-check-to-allow-comparison-between-unsigned-arguments-and-signed-constants.patch
queue-5.10/minmax-clamp-more-efficiently-by-avoiding-extra-comparison.patch
queue-5.10/minmax.h-update-some-comments.patch
