From: Eliav Farber <farbere@amazon•com>
To: <gregkh@linuxfoundation•org>, <stable@vger•kernel.org>,
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Cc: Linus Torvalds <torvalds@linux-foundation•org>,
David Laight <David.Laight@aculab•com>,
Lorenzo Stoakes <lorenzo.stoakes@oracle•com>
Subject: [PATCH v2 15/27 5.10.y] minmax: simplify and clarify min_t()/max_t() implementation
Date: Fri, 17 Oct 2025 09:05:07 +0000 [thread overview]
Message-ID: <20251017090519.46992-16-farbere@amazon.com> (raw)
In-Reply-To: <20251017090519.46992-1-farbere@amazon.com>
From: Linus Torvalds <torvalds@linux-foundation•org>
[ 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 <David.Laight@aculab•com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle•com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation•org>
Signed-off-by: Eliav Farber <farbere@amazon•com>
---
include/linux/minmax.h | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index a7ef65f78933..9c2848abc804 100644
--- 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().
--
2.47.3
next prev parent reply other threads:[~2025-10-17 9:10 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-17 9:04 [PATCH v2 00/27 5.10.y] Backport minmax.h updates from v6.17-rc7 Eliav Farber
2025-10-17 9:04 ` [PATCH v2 01/27 5.10.y] overflow, tracing: Define the is_signed_type() macro once Eliav Farber
2025-10-17 11:59 ` Greg KH
2025-10-17 12:16 ` Farber, Eliav
2025-10-17 13:21 ` Greg KH
2025-10-17 9:04 ` [PATCH v2 02/27 5.10.y] btrfs: remove duplicated in_range() macro Eliav Farber
2025-10-17 9:04 ` [PATCH v2 03/27 5.10.y] minmax: sanity check constant bounds when clamping Eliav Farber
2025-10-17 9:04 ` [PATCH v2 04/27 5.10.y] minmax: clamp more efficiently by avoiding extra comparison Eliav Farber
2025-10-17 9:04 ` [PATCH v2 05/27 5.10.y] minmax: add in_range() macro Eliav Farber
2025-10-17 9:04 ` [PATCH v2 06/27 5.10.y] minmax: Introduce {min,max}_array() Eliav Farber
2025-10-17 9:04 ` [PATCH v2 07/27 5.10.y] minmax: deduplicate __unconst_integer_typeof() Eliav Farber
2025-10-17 9:05 ` [PATCH v2 08/27 5.10.y] minmax: fix header inclusions Eliav Farber
2025-10-17 9:05 ` [PATCH v2 09/27 5.10.y] minmax: allow min()/max()/clamp() if the arguments have the same signedness Eliav Farber
2025-10-17 9:05 ` [PATCH v2 10/27 5.10.y] minmax: fix indentation of __cmp_once() and __clamp_once() Eliav Farber
2025-10-17 9:05 ` [PATCH v2 11/27 5.10.y] minmax: allow comparisons of 'int' against 'unsigned char/short' Eliav Farber
2025-10-17 9:05 ` [PATCH v2 12/27 5.10.y] minmax: relax check to allow comparison between unsigned arguments and signed constants Eliav Farber
2025-10-17 9:05 ` [PATCH v2 13/27 5.10.y] minmax: avoid overly complicated constant expressions in VM code Eliav Farber
2025-10-17 9:05 ` [PATCH v2 14/27 5.10.y] minmax: add a few more MIN_T/MAX_T users Eliav Farber
2025-10-17 9:05 ` Eliav Farber [this message]
2025-10-17 9:05 ` [PATCH v2 16/27 5.10.y] minmax: make generic MIN() and MAX() macros available everywhere Eliav Farber
2025-10-17 9:05 ` [PATCH v2 17/27 5.10.y] minmax: don't use max() in situations that want a C constant expression Eliav Farber
2025-10-17 9:05 ` [PATCH v2 18/27 5.10.y] minmax: simplify min()/max()/clamp() implementation Eliav Farber
2025-10-17 9:05 ` [PATCH v2 19/27 5.10.y] minmax: improve macro expansion and type checking Eliav Farber
2025-10-17 9:05 ` [PATCH v2 20/27 5.10.y] minmax: fix up min3() and max3() too Eliav Farber
2025-10-17 9:05 ` [PATCH v2 21/27 5.10.y] minmax.h: add whitespace around operators and after commas Eliav Farber
2025-10-17 9:05 ` [PATCH v2 22/27 5.10.y] minmax.h: update some comments Eliav Farber
2025-10-17 9:05 ` [PATCH v2 23/27 5.10.y] minmax.h: reduce the #define expansion of min(), max() and clamp() Eliav Farber
2025-10-17 9:05 ` [PATCH v2 24/27 5.10.y] minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp() Eliav Farber
2025-10-17 9:05 ` [PATCH v2 25/27 5.10.y] minmax.h: move all the clamp() definitions after the min/max() ones Eliav Farber
2025-10-17 9:05 ` [PATCH v2 26/27 5.10.y] minmax.h: simplify the variants of clamp() Eliav Farber
2025-10-17 9:05 ` [PATCH v2 27/27 5.10.y] minmax.h: remove some #defines that are only expanded once Eliav Farber
2025-10-17 15:03 ` [PATCH v2 00/27 5.10.y] Backport minmax.h updates from v6.17-rc7 Greg KH
2025-10-17 16:09 ` Nathan Chancellor
2025-10-19 12:38 ` Greg KH
2025-10-18 20:07 ` Farber, Eliav
2025-10-19 12:37 ` Greg KH
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