linux-kernel - [PATCH v2 10/13 6.1.y] minmax.h: use BUILD_BUG_ON

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Message-ID: <20250929183358.18982-11-farbere@amazon.com>
Date: Mon, 29 Sep 2025 18:33:55 +0000
From: Eliav Farber <farbere@...zon.com>
To: <gregkh@...uxfoundation.org>, <sashal@...nel.org>,
	<mario.limonciello@....com>, <lijo.lazar@....com>, <David.Laight@...LAB.COM>,
	<arnd@...nel.org>, <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>,
	<farbere@...zon.com>
CC: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Christoph Hellwig
	<hch@...radead.org>, Dan Carpenter <dan.carpenter@...aro.org>, "Jason A.
 Donenfeld" <Jason@...c4.com>, Jens Axboe <axboe@...nel.dk>, Lorenzo Stoakes
	<lorenzo.stoakes@...cle.com>, Mateusz Guzik <mjguzik@...il.com>, "Matthew
 Wilcox" <willy@...radead.org>, Pedro Falcato <pedro.falcato@...il.com>
Subject: [PATCH v2 10/13 6.1.y] minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()

From: David Laight <David.Laight@...LAB.COM>

[ 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@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@...lab.com>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Arnd Bergmann <arnd@...nel.org>
Cc: Christoph Hellwig <hch@...radead.org>
Cc: Dan Carpenter <dan.carpenter@...aro.org>
Cc: Jason A. Donenfeld <Jason@...c4.com>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Mateusz Guzik <mjguzik@...il.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Pedro Falcato <pedro.falcato@...il.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Eliav Farber <farbere@...zon.com>
---
 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