linux-kernel - [PATCH next 6/7] minmax.h: Simplify the variants of clamp()

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Message-ID: <8f69f4deac014f558bab186444bac2e8@AcuMS.aculab.com>
Date: Mon, 18 Nov 2024 19:15:05 +0000
From: David Laight <David.Laight@...LAB.COM>
To: Linus Torvalds <torvalds@...ux-foundation.org>
CC: 'Arnd Bergmann' <arnd@...nel.org>, "'linux-kernel@...r.kernel.org'"
	<linux-kernel@...r.kernel.org>, 'Jens Axboe' <axboe@...nel.dk>, "'Matthew
 Wilcox'" <willy@...radead.org>, 'Christoph Hellwig' <hch@...radead.org>,
	'Andrew Morton' <akpm@...ux-foundation.org>, 'Andy Shevchenko'
	<andriy.shevchenko@...ux.intel.com>, 'Dan Carpenter'
	<dan.carpenter@...aro.org>, "'Jason A . Donenfeld'" <Jason@...c4.com>,
	"'pedro.falcato@...il.com'" <pedro.falcato@...il.com>, 'Mateusz Guzik'
	<mjguzik@...il.com>, "'linux-mm@...ck.org'" <linux-mm@...ck.org>, "'Lorenzo
 Stoakes'" <lorenzo.stoakes@...cle.com>
Subject: [PATCH next 6/7] minmax.h: Simplify the variants of clamp()

Always pass a 'type' through to __clamp_once(), pass '__auto_type'
from clamp() itself.

The expansion of __types_ok3() is reasonable so it isn't worth the
added complexity of avoiding it when a fixed type is used for all
three values.

Signed-off-by: David Laight <david.laight@...lab.com>
---
 include/linux/minmax.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 75fb7a6ad4c6..2bbdd5b5e07e 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -183,29 +183,29 @@
 #define __clamp(val, lo, hi)	\
 	((val) >= (hi) ? (hi) : ((val) <= (lo) ? (lo) : (val)))
 
-#define __clamp_once(val, lo, hi, uval, ulo, uhi) ({				\
-	__auto_type uval = (val);						\
-	__auto_type ulo = (lo);							\
-	__auto_type uhi = (hi);							\
+#define __clamp_once(type, val, lo, hi, uval, ulo, uhi) ({			\
+	type uval = (val);							\
+	type ulo = (lo);							\
+	type uhi = (hi);							\
 	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");		\
 	__clamp(uval, ulo, uhi); })
 
-#define __careful_clamp(val, lo, hi) \
-	__clamp_once(val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_), __UNIQUE_ID(h_))
+#define __careful_clamp(type, val, lo, hi) \
+	__clamp_once(type, val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_), __UNIQUE_ID(h_))
 
 /**
- * clamp - return a value clamped to a given range with strict typechecking
+ * clamp - return a value clamped to a given range with typechecking
  * @val: current value
  * @lo: lowest allowable value
  * @hi: highest allowable value
  *
- * This macro does strict typechecking of @lo/@hi to make sure they are of the
- * same type as @val.  See the unnecessary pointer comparisons.
+ * This macro checks @val/@lo/@hi to make sure they have compatible
+ * signedness.
  */
-#define clamp(val, lo, hi) __careful_clamp(val, lo, hi)
+#define clamp(val, lo, hi) __careful_clamp(__auto_type, val, lo, hi)
 
 /**
  * clamp_t - return a value clamped to a given range using a given type
@@ -217,7 +217,7 @@
  * This macro does no typechecking and uses temporary variables of type
  * @type to make all the comparisons.
  */
-#define clamp_t(type, val, lo, hi) __careful_clamp((type)(val), (type)(lo), (type)(hi))
+#define clamp_t(type, val, lo, hi) __careful_clamp(type, val, lo, hi)
 
 /**
  * clamp_val - return a value clamped to a given range using val's type
@@ -230,7 +230,7 @@
  * type and @lo and @hi are literals that will otherwise be assigned a signed
  * integer type.
  */
-#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
+#define clamp_val(val, lo, hi) __careful_clamp(typeof(val), val, lo, hi)
 
 /*
  * Do not check the array parameter using __must_be_array().
-- 
2.17.1

-
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