This is a note to let you know that I've just added the patch titled
minmax: simplify and clarify min_t()/max_t() implementation
to the 6.6-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-simplify-and-clarify-min_t-max_t-implementation.patch
and it can be found in the queue-6.6 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] Mon Sep 22 12:34:24 2025
From: Eliav Farber <[email protected]>
Date: Mon, 22 Sep 2025 10:32:28 +0000
Subject: minmax: simplify and clarify min_t()/max_t() implementation
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Cc: Linus Torvalds <[email protected]>, David Laight
<[email protected]>, Lorenzo Stoakes <[email protected]>
Message-ID: <[email protected]>
From: Linus Torvalds <[email protected]>
[ Upstream commit 017fa3e89187848fd056af757769c9e66ac3e93d ]
This simplifies the min_t() and max_t() macros by no longer making them
work in the context of a C constant expression.
That means that you can no longer use them for static initializers or
for array sizes in type definitions, but there were only a couple of
such uses, and all of them were converted (famous last words) to use
MIN_T/MAX_T instead.
Cc: David Laight <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Eliav Farber <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
include/linux/minmax.h | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -45,17 +45,20 @@
#define __cmp(op, x, y) ((x) __cmp_op_##op (y) ? (x) : (y))
-#define __cmp_once(op, x, y, unique_x, unique_y) ({ \
- typeof(x) unique_x = (x); \
- typeof(y) unique_y = (y); \
+#define __cmp_once_unique(op, type, x, y, ux, uy) \
+ ({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
+
+#define __cmp_once(op, type, x, y) \
+ __cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
+
+#define __careful_cmp_once(op, x, y) ({ \
static_assert(__types_ok(x, y), \
#op "(" #x ", " #y ") signedness error, fix types or consider
u" #op "() before " #op "_t()"); \
- __cmp(op, unique_x, unique_y); })
+ __cmp_once(op, __auto_type, x, y); })
#define __careful_cmp(op, x, y) \
__builtin_choose_expr(__is_constexpr((x) - (y)), \
- __cmp(op, x, y), \
- __cmp_once(op, x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y)))
+ __cmp(op, x, y), __careful_cmp_once(op, x, y))
#define __clamp(val, lo, hi) \
((val) >= (hi) ? (hi) : ((val) <= (lo) ? (lo) : (val)))
@@ -158,7 +161,7 @@
* @x: first value
* @y: second value
*/
-#define min_t(type, x, y) __careful_cmp(min, (type)(x), (type)(y))
+#define min_t(type, x, y) __cmp_once(min, type, x, y)
/**
* max_t - return maximum of two values, using the specified type
@@ -166,7 +169,7 @@
* @x: first value
* @y: second value
*/
-#define max_t(type, x, y) __careful_cmp(max, (type)(x), (type)(y))
+#define max_t(type, x, y) __cmp_once(max, type, x, y)
/*
* Do not check the array parameter using __must_be_array().
Patches currently in stable-queue which might be from [email protected] are
queue-6.6/minmax-don-t-use-max-in-situations-that-want-a-c-constant-expression.patch
queue-6.6/minmax-make-generic-min-and-max-macros-available-everywhere.patch
queue-6.6/minmax-fix-up-min3-and-max3-too.patch
queue-6.6/minmax-add-a-few-more-min_t-max_t-users.patch
queue-6.6/minmax-improve-macro-expansion-and-type-checking.patch
queue-6.6/minmax-avoid-overly-complicated-constant-expressions-in-vm-code.patch
queue-6.6/minmax-simplify-min-max-clamp-implementation.patch
queue-6.6/minmax-simplify-and-clarify-min_t-max_t-implementation.patch
