Patch "minmax.h: simplify the variants of clamp()" has been added to the 6.1-stable tree

Mon Oct 6 03:39:12 PDT 2025

This is a note to let you know that I've just added the patch titled

    minmax.h: simplify the variants of clamp()

to the 6.1-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.h-simplify-the-variants-of-clamp.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From stable+bounces-183181-greg=kroah.com at vger.kernel.org Fri Oct  3 14:28:17 2025
From: Eliav Farber <farbere at amazon.com>
Date: Fri, 3 Oct 2025 12:15:19 +0000
Subject: minmax.h: simplify the variants of clamp()
To: <gregkh at linuxfoundation.org>, <kenneth.feng at amd.com>, <alexander.deucher at amd.com>, <christian.koenig at amd.com>, <airlied at gmail.com>, <simona at ffwll.ch>, <linus.walleij at linaro.org>, <dmitry.torokhov at gmail.com>, <tglx at linutronix.de>, <wens at csie.org>, <jernej.skrabec at gmail.com>, <samuel at sholland.org>, <agk at redhat.com>, <snitzer at kernel.org>, <mpatocka at redhat.com>, <clm at fb.com>, <dsterba at suse.com>, <luc.vanoostenryck at gmail.com>, <pmladek at suse.com>, <rostedt at goodmis.org>, <andriy.shevchenko at linux.intel.com>, <linux at rasmusvillemoes.dk>, <senozhatsky at chromium.org>, <akpm at linux-foundation.org>, <lijo.lazar at amd.com>, <asad.kamal at amd.com>, <kevinyang.wang at amd.com>, <David.Laight at ACULAB.COM>, <amd-gfx at lists.freedesktop.org>, <dri-devel at lists.freedesktop.org>, <linux-kernel at vger.kernel.org>, <linux-input at vger.kernel.org>, <linux-arm-kernel at lists.infradead.org>, <linux-sunxi at lists.linux.dev>, <dm-devel at lists.linux.dev>, <linux-btrfs at vger.kernel.org>, <linux-sparse at vger.kernel.org>, <stable at vger.
 kernel.org>, <farbere at amazon.com>
Cc: Arnd Bergmann <arnd at kernel.org>, Christoph Hellwig <hch at infradead.org>, Dan Carpenter <dan.carpenter at linaro.org>, "Jason A. Donenfeld" <Jason at zx2c4.com>, Jens Axboe <axboe at kernel.dk>, Lorenzo Stoakes <lorenzo.stoakes at oracle.com>, Mateusz Guzik <mjguzik at gmail.com>, "Matthew Wilcox" <willy at infradead.org>, Pedro Falcato <pedro.falcato at gmail.com>
Message-ID: <20251003121520.8176-11-farbere at amazon.com>

From: David Laight <David.Laight at ACULAB.COM>

[ Upstream commit 495bba17cdf95e9703af1b8ef773c55ef0dfe703 ]

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.

Link: https://lkml.kernel.org/r/8f69f4deac014f558bab186444bac2e8@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight at aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Cc: Arnd Bergmann <arnd at kernel.org>
Cc: Christoph Hellwig <hch at infradead.org>
Cc: Dan Carpenter <dan.carpenter at linaro.org>
Cc: Jason A. Donenfeld <Jason at zx2c4.com>
Cc: Jens Axboe <axboe at kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes at oracle.com>
Cc: Mateusz Guzik <mjguzik at gmail.com>
Cc: Matthew Wilcox <willy at infradead.org>
Cc: Pedro Falcato <pedro.falcato at gmail.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Eliav Farber <farbere at amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 include/linux/minmax.h |   24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

--- 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().


Patches currently in stable-queue which might be from farbere at amazon.com are

queue-6.1/minmax-improve-macro-expansion-and-type-checking.patch
queue-6.1/minmax.h-simplify-the-variants-of-clamp.patch
queue-6.1/minmax.h-move-all-the-clamp-definitions-after-the-min-max-ones.patch
queue-6.1/minmax-don-t-use-max-in-situations-that-want-a-c-constant-expression.patch
queue-6.1/minmax.h-remove-some-defines-that-are-only-expanded-once.patch
queue-6.1/minmax.h-use-build_bug_on_msg-for-the-lo-hi-test-in-clamp.patch
queue-6.1/minmax-simplify-min-max-clamp-implementation.patch
queue-6.1/minmax.h-add-whitespace-around-operators-and-after-commas.patch
queue-6.1/minmax-fix-up-min3-and-max3-too.patch
queue-6.1/minmax.h-reduce-the-define-expansion-of-min-max-and-clamp.patch
queue-6.1/minmax.h-update-some-comments.patch

