[PATCH v2 09/12 6.6.y] minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()
From: Eliav Farber
Date: Mon Sep 29 2025 - 13:18:59 EST
From: David Laight <David.Laight@xxxxxxxxxx>
[ Upstream commit a5743f32baec4728711bbc01d6ac2b33d4c67040 ]
Use BUILD_BUG_ON_MSG(statically_true(ulo > uhi), ...) for the sanity check
of the bounds in clamp(). Gives better error coverage and one less
expansion of the arguments.
Link: https://lkml.kernel.org/r/34d53778977747f19cce2abb287bb3e6@xxxxxxxxxxxxxxxx
Signed-off-by: David Laight <david.laight@xxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: Jason A. Donenfeld <Jason@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Cc: Mateusz Guzik <mjguzik@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Pedro Falcato <pedro.falcato@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Eliav Farber <farbere@xxxxxxxxxx>
---
include/linux/minmax.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 6f7ea669d305..91aa1b90c1bb 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -106,8 +106,7 @@
__auto_type uval = (val); \
__auto_type ulo = (lo); \
__auto_type uhi = (hi); \
- static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), \
- (lo) <= (hi), true), \
+ BUILD_BUG_ON_MSG(statically_true(ulo > uhi), \
"clamp() low limit " #lo " greater than high limit " #hi); \
BUILD_BUG_ON_MSG(!__types_ok3(uval, ulo, uhi), \
"clamp("#val", "#lo", "#hi") signedness error"); \
--
2.47.3