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Backport minmax.h updates from v6.17-rc7

PATCH In review Eliav Farber 2 participants 10 messages Sep 22, 2025 Stable branch

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#0 lore raw

cover Backport minmax.h updates from v6.17-rc7

This series backports 7 patches to update minmax.h in the 6.12.y branch, aligning it with v6.17-rc7.

The ultimate goal is to synchronize all longterm branches so that they include the full set of minmax.h changes.

The key motivation is to bring in commit d03eba99f5bf ("minmax: allow min()/max()/clamp() if the arguments have the same signedness"), which is missing in older kernels.

In mainline, this change enables min()/max()/clamp() to accept mixed argument types, provided both have the same signedness. Without it, backported patches that use these forms may trigger compiler warnings, which escalate to build failures when -Werror is enabled.

David Laight (7):
minmax.h: add whitespace around operators and after commas minmax.h: update some comments
minmax.h: reduce the #define expansion of min(), max() and clamp() minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp() minmax.h: move all the clamp() definitions after the min/max() ones minmax.h: simplify the variants of clamp()
minmax.h: remove some #defines that are only expanded once

 include/linux/minmax.h | 205 +++++++++++++++++++----------------------
 1 file changed, 95 insertions(+), 110 deletions(-)
Signature · 1 line
2.47.3
#1 lore raw

PATCH 1/7 minmax.h: add whitespace around operators and after commas

From: David Laight <[email protected]>

[ Upstream commit 71ee9b16251ea4bf7c1fe222517c82bdb3220acc ]

Patch series "minmax.h: Cleanups and minor optimisations".

Some tidyups and minor changes to minmax.h.

This patch (of 7):

---
 include/linux/minmax.h | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)
include/linux/minmax.h +17 -17
index 98008dd92153..51b0d988e322 100644
@@ -51,10 +51,10 @@
  * only need to be careful to not cause warnings for
  * pointer use.
  */
-#define __signed_type_use(x,ux) (2+__is_nonneg(x,ux))
-#define __unsigned_type_use(x,ux) (1+2*(sizeof(ux)<4))
-#define __sign_use(x,ux) (is_signed_type(typeof(ux))? \
-	__signed_type_use(x,ux):__unsigned_type_use(x,ux))
+#define __signed_type_use(x, ux) (2 + __is_nonneg(x, ux))
+#define __unsigned_type_use(x, ux) (1 + 2 * (sizeof(ux) < 4))
+#define __sign_use(x, ux) (is_signed_type(typeof(ux)) ? \
+	__signed_type_use(x, ux) : __unsigned_type_use(x, ux))
 
 /*
  * To avoid warnings about casting pointers to integers
@@ -74,15 +74,15 @@
 #ifdef CONFIG_64BIT
   #define __signed_type(ux) long
 #else
-  #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux)>4,1LL,1L))
+  #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux) > 4, 1LL, 1L))
 #endif
-#define __is_nonneg(x,ux) statically_true((__signed_type(ux))(x)>=0)
+#define __is_nonneg(x, ux) statically_true((__signed_type(ux))(x) >= 0)
 
-#define __types_ok(x,y,ux,uy) \
-	(__sign_use(x,ux) & __sign_use(y,uy))
+#define __types_ok(x, y, ux, uy) \
+	(__sign_use(x, ux) & __sign_use(y, uy))
 
-#define __types_ok3(x,y,z,ux,uy,uz) \
-	(__sign_use(x,ux) & __sign_use(y,uy) & __sign_use(z,uz))
+#define __types_ok3(x, y, z, ux, uy, uz) \
+	(__sign_use(x, ux) & __sign_use(y, uy) & __sign_use(z, uz))
 
 #define __cmp_op_min <
 #define __cmp_op_max >
@@ -97,7 +97,7 @@
 
 #define __careful_cmp_once(op, x, y, ux, uy) ({		\
 	__auto_type ux = (x); __auto_type uy = (y);	\
-	BUILD_BUG_ON_MSG(!__types_ok(x,y,ux,uy),	\
+	BUILD_BUG_ON_MSG(!__types_ok(x, y, ux, uy),	\
 		#op"("#x", "#y") signedness error");	\
 	__cmp(op, ux, uy); })
 
@@ -114,7 +114,7 @@
 	static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), 	\
 			(lo) <= (hi), true),					\
 		"clamp() low limit " #lo " greater than high limit " #hi);	\
-	BUILD_BUG_ON_MSG(!__types_ok3(val,lo,hi,uval,ulo,uhi),			\
+	BUILD_BUG_ON_MSG(!__types_ok3(val, lo, hi, uval, ulo, uhi),		\
 		"clamp("#val", "#lo", "#hi") signedness error");		\
 	__clamp(uval, ulo, uhi); })
 
@@ -154,7 +154,7 @@
 
 #define __careful_op3(op, x, y, z, ux, uy, uz) ({			\
 	__auto_type ux = (x); __auto_type uy = (y);__auto_type uz = (z);\
-	BUILD_BUG_ON_MSG(!__types_ok3(x,y,z,ux,uy,uz),			\
+	BUILD_BUG_ON_MSG(!__types_ok3(x, y, z, ux, uy, uz),		\
 		#op"3("#x", "#y", "#z") signedness error");		\
 	__cmp(op, ux, __cmp(op, uy, uz)); })
 
@@ -326,9 +326,9 @@ static inline bool in_range32(u32 val, u32 start, u32 len)
  * Use these carefully: no type checking, and uses the arguments
  * multiple times. Use for obvious constants only.
  */
-#define MIN(a,b) __cmp(min,a,b)
-#define MAX(a,b) __cmp(max,a,b)
-#define MIN_T(type,a,b) __cmp(min,(type)(a),(type)(b))
-#define MAX_T(type,a,b) __cmp(max,(type)(a),(type)(b))
+#define MIN(a, b) __cmp(min, a, b)
+#define MAX(a, b) __cmp(max, a, b)
+#define MIN_T(type, a, b) __cmp(min, (type)(a), (type)(b))
+#define MAX_T(type, a, b) __cmp(max, (type)(a), (type)(b))
 
 #endif	/* _LINUX_MINMAX_H */
Signature · 1 line
2.47.3
#2 lore raw

PATCH 2/7 minmax.h: update some comments

In reply to Eliav Farber

From: David Laight <[email protected]>

[ Upstream commit 10666e99204818ef45c702469488353b5bb09ec7 ]

- Change three to several.
- Remove the comment about retaining constant expressions, no longer true.
- Realign to nearer 80 columns and break on major punctiation.
- Add a leading comment to the block before __signed_type() and __is_nonneg() Otherwise the block explaining the cast is a bit 'floating'. Reword the rest of that comment to improve readability.

Cc Andy Shevchenko <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc Christoph Hellwig <[email protected]>
Cc Dan Carpenter <[email protected]>
Cc Jason A. Donenfeld <[email protected]>
Cc Jens Axboe <[email protected]>
Cc Lorenzo Stoakes <[email protected]>
Cc Mateusz Guzik <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc Pedro Falcato <[email protected]>
---
 include/linux/minmax.h | 53 +++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 29 deletions(-)
include/linux/minmax.h +24 -29
index 51b0d988e322..24e4b372649a 100644
@@ -8,13 +8,10 @@
 #include <linux/types.h>
 
 /*
- * min()/max()/clamp() macros must accomplish three things:
+ * min()/max()/clamp() macros must accomplish several things:
  *
  * - Avoid multiple evaluations of the arguments (so side-effects like
  *   "x++" happen only once) when non-constant.
- * - Retain result as a constant expressions when called with only
- *   constant expressions (to avoid tripping VLA warnings in stack
- *   allocation usage).
  * - Perform signed v unsigned type-checking (to generate compile
  *   errors instead of nasty runtime surprises).
  * - Unsigned char/short are always promoted to signed int and can be
@@ -31,25 +28,23 @@
  *   bit #0 set if ok for unsigned comparisons
  *   bit #1 set if ok for signed comparisons
  *
- * In particular, statically non-negative signed integer
- * expressions are ok for both.
+ * In particular, statically non-negative signed integer expressions
+ * are ok for both.
  *
- * NOTE! Unsigned types smaller than 'int' are implicitly
- * converted to 'int' in expressions, and are accepted for
- * signed conversions for now. This is debatable.
+ * NOTE! Unsigned types smaller than 'int' are implicitly converted to 'int'
+ * in expressions, and are accepted for signed conversions for now.
+ * This is debatable.
  *
- * Note that 'x' is the original expression, and 'ux' is
- * the unique variable that contains the value.
+ * Note that 'x' is the original expression, and 'ux' is the unique variable
+ * that contains the value.
  *
- * We use 'ux' for pure type checking, and 'x' for when
- * we need to look at the value (but without evaluating
- * it for side effects! Careful to only ever evaluate it
- * with sizeof() or __builtin_constant_p() etc).
+ * We use 'ux' for pure type checking, and 'x' for when we need to look at the
+ * value (but without evaluating it for side effects!
+ * Careful to only ever evaluate it with sizeof() or __builtin_constant_p() etc).
  *
- * Pointers end up being checked by the normal C type
- * rules at the actual comparison, and these expressions
- * only need to be careful to not cause warnings for
- * pointer use.
+ * Pointers end up being checked by the normal C type rules at the actual
+ * comparison, and these expressions only need to be careful to not cause
+ * warnings for pointer use.
  */
 #define __signed_type_use(x, ux) (2 + __is_nonneg(x, ux))
 #define __unsigned_type_use(x, ux) (1 + 2 * (sizeof(ux) < 4))
@@ -57,19 +52,19 @@
 	__signed_type_use(x, ux) : __unsigned_type_use(x, ux))
 
 /*
- * To avoid warnings about casting pointers to integers
- * of different sizes, we need that special sign type.
+ * Check whether a signed value is always non-negative.
  *
- * On 64-bit we can just always use 'long', since any
- * integer or pointer type can just be cast to that.
+ * A cast is needed to avoid any warnings from values that aren't signed
+ * integer types (in which case the result doesn't matter).
  *
- * This does not work for 128-bit signed integers since
- * the cast would truncate them, but we do not use s128
- * types in the kernel (we do use 'u128', but they will
- * be handled by the !is_signed_type() case).
+ * On 64-bit any integer or pointer type can safely be cast to 'long'.
+ * But on 32-bit we need to avoid warnings about casting pointers to integers
+ * of different sizes without truncating 64-bit values so 'long' or 'long long'
+ * must be used depending on the size of the value.
  *
- * NOTE! The cast is there only to avoid any warnings
- * from when values that aren't signed integer types.
+ * This does not work for 128-bit signed integers since the cast would truncate
+ * them, but we do not use s128 types in the kernel (we do use 'u128',
+ * but they are handled by the !is_signed_type() case).
  */
 #ifdef CONFIG_64BIT
   #define __signed_type(ux) long
Signature · 1 line
2.47.3
#3 lore raw

PATCH 3/7 minmax.h: reduce the #define expansion of min(), max() and clamp()

In reply to Eliav Farber

From: David Laight <[email protected]>

[ Upstream commit b280bb27a9f7c91ddab730e1ad91a9c18a051f41 ]

Since the test for signed values being non-negative only relies on __builtion_constant_p() (not is_constexpr()) it can use the 'ux' variable instead of the caller supplied expression. This means that the #define parameters are only expanded twice. Once in the code and once quoted in the error message.

Cc Andy Shevchenko <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc Christoph Hellwig <[email protected]>
Cc Dan Carpenter <[email protected]>
Cc Jason A. Donenfeld <[email protected]>
Cc Jens Axboe <[email protected]>
Cc Lorenzo Stoakes <[email protected]>
Cc Mateusz Guzik <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc Pedro Falcato <[email protected]>
---
 include/linux/minmax.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)
include/linux/minmax.h +12 -12
index 24e4b372649a..6f7ea669d305 100644
@@ -46,10 +46,10 @@
  * comparison, and these expressions only need to be careful to not cause
  * warnings for pointer use.
  */
-#define __signed_type_use(x, ux) (2 + __is_nonneg(x, ux))
-#define __unsigned_type_use(x, ux) (1 + 2 * (sizeof(ux) < 4))
-#define __sign_use(x, ux) (is_signed_type(typeof(ux)) ? \
-	__signed_type_use(x, ux) : __unsigned_type_use(x, ux))
+#define __signed_type_use(ux) (2 + __is_nonneg(ux))
+#define __unsigned_type_use(ux) (1 + 2 * (sizeof(ux) < 4))
+#define __sign_use(ux) (is_signed_type(typeof(ux)) ? \
+	__signed_type_use(ux) : __unsigned_type_use(ux))
 
 /*
  * Check whether a signed value is always non-negative.
@@ -71,13 +71,13 @@
 #else
   #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux) > 4, 1LL, 1L))
 #endif
-#define __is_nonneg(x, ux) statically_true((__signed_type(ux))(x) >= 0)
+#define __is_nonneg(ux) statically_true((__signed_type(ux))(ux) >= 0)
 
-#define __types_ok(x, y, ux, uy) \
-	(__sign_use(x, ux) & __sign_use(y, uy))
+#define __types_ok(ux, uy) \
+	(__sign_use(ux) & __sign_use(uy))
 
-#define __types_ok3(x, y, z, ux, uy, uz) \
-	(__sign_use(x, ux) & __sign_use(y, uy) & __sign_use(z, uz))
+#define __types_ok3(ux, uy, uz) \
+	(__sign_use(ux) & __sign_use(uy) & __sign_use(uz))
 
 #define __cmp_op_min <
 #define __cmp_op_max >
@@ -92,7 +92,7 @@
 
 #define __careful_cmp_once(op, x, y, ux, uy) ({		\
 	__auto_type ux = (x); __auto_type uy = (y);	\
-	BUILD_BUG_ON_MSG(!__types_ok(x, y, ux, uy),	\
+	BUILD_BUG_ON_MSG(!__types_ok(ux, uy),		\
 		#op"("#x", "#y") signedness error");	\
 	__cmp(op, ux, uy); })
 
@@ -109,7 +109,7 @@
 	static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), 	\
 			(lo) <= (hi), true),					\
 		"clamp() low limit " #lo " greater than high limit " #hi);	\
-	BUILD_BUG_ON_MSG(!__types_ok3(val, lo, hi, uval, ulo, uhi),		\
+	BUILD_BUG_ON_MSG(!__types_ok3(uval, ulo, uhi),				\
 		"clamp("#val", "#lo", "#hi") signedness error");		\
 	__clamp(uval, ulo, uhi); })
 
@@ -149,7 +149,7 @@
 
 #define __careful_op3(op, x, y, z, ux, uy, uz) ({			\
 	__auto_type ux = (x); __auto_type uy = (y);__auto_type uz = (z);\
-	BUILD_BUG_ON_MSG(!__types_ok3(x, y, z, ux, uy, uz),		\
+	BUILD_BUG_ON_MSG(!__types_ok3(ux, uy, uz),			\
 		#op"3("#x", "#y", "#z") signedness error");		\
 	__cmp(op, ux, __cmp(op, uy, uz)); })
 
Signature · 1 line
2.47.3
#4 lore raw

PATCH 4/7 minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()

In reply to Eliav Farber

From: David Laight <[email protected]>

[ 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.

Cc Andy Shevchenko <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc Christoph Hellwig <[email protected]>
Cc Dan Carpenter <[email protected]>
Cc Jason A. Donenfeld <[email protected]>
Cc Jens Axboe <[email protected]>
Cc Lorenzo Stoakes <[email protected]>
Cc Mateusz Guzik <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc Pedro Falcato <[email protected]>
---
 include/linux/minmax.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
include/linux/minmax.h +1 -2
index 6f7ea669d305..91aa1b90c1bb 100644
@@ -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");		\
Signature · 1 line
2.47.3
#5 lore raw

PATCH 5/7 minmax.h: move all the clamp() definitions after the min/max() ones

In reply to Eliav Farber

From: David Laight <[email protected]>

[ Upstream commit c3939872ee4a6b8bdcd0e813c66823b31e6e26f7 ]

At some point the definitions for clamp() got added in the middle of the ones for min() and max(). Re-order the definitions so they are more sensibly grouped.

Cc Andy Shevchenko <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc Christoph Hellwig <[email protected]>
Cc Dan Carpenter <[email protected]>
Cc Jason A. Donenfeld <[email protected]>
Cc Jens Axboe <[email protected]>
Cc Lorenzo Stoakes <[email protected]>
Cc Mateusz Guzik <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc Pedro Falcato <[email protected]>
---
 include/linux/minmax.h | 109 +++++++++++++++++++----------------------
 1 file changed, 51 insertions(+), 58 deletions(-)
include/linux/minmax.h +51 -58
index 91aa1b90c1bb..75fb7a6ad4c6 100644
@@ -99,22 +99,6 @@
 #define __careful_cmp(op, x, y) \
 	__careful_cmp_once(op, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
 
-#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);							\
-	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_))
-
 /**
  * min - return minimum of two values of the same or compatible types
  * @x: first value
@@ -170,6 +154,22 @@
 #define max3(x, y, z) \
 	__careful_op3(max, x, y, z, __UNIQUE_ID(x_), __UNIQUE_ID(y_), __UNIQUE_ID(z_))
 
+/**
+ * min_t - return minimum of two values, using the specified type
+ * @type: data type to use
+ * @x: first value
+ * @y: second value
+ */
+#define min_t(type, x, y) __cmp_once(min, type, x, y)
+
+/**
+ * max_t - return maximum of two values, using the specified type
+ * @type: data type to use
+ * @x: first value
+ * @y: second value
+ */
+#define max_t(type, x, y) __cmp_once(max, type, x, y)
+
 /**
  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
  * @x: value1
@@ -180,6 +180,22 @@
 	typeof(y) __y = (y);			\
 	__x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 
+#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);							\
+	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_))
+
 /**
  * clamp - return a value clamped to a given range with strict typechecking
  * @val: current value
@@ -191,28 +207,30 @@
  */
 #define clamp(val, lo, hi) __careful_clamp(val, lo, hi)
 
-/*
- * ..and if you can't take the strict
- * types, you can specify one yourself.
- *
- * Or not use min/max/clamp at all, of course.
- */
-
 /**
- * min_t - return minimum of two values, using the specified type
- * @type: data type to use
- * @x: first value
- * @y: second value
+ * clamp_t - return a value clamped to a given range using a given type
+ * @type: the type of variable to use
+ * @val: current value
+ * @lo: minimum allowable value
+ * @hi: maximum allowable value
+ *
+ * This macro does no typechecking and uses temporary variables of type
+ * @type to make all the comparisons.
  */
-#define min_t(type, x, y) __cmp_once(min, type, x, y)
+#define clamp_t(type, val, lo, hi) __careful_clamp((type)(val), (type)(lo), (type)(hi))
 
 /**
- * max_t - return maximum of two values, using the specified type
- * @type: data type to use
- * @x: first value
- * @y: second value
+ * clamp_val - return a value clamped to a given range using val's type
+ * @val: current value
+ * @lo: minimum allowable value
+ * @hi: maximum allowable value
+ *
+ * This macro does no typechecking and uses temporary variables of whatever
+ * type the input argument @val is.  This is useful when @val is an unsigned
+ * type and @lo and @hi are literals that will otherwise be assigned a signed
+ * integer type.
  */
-#define max_t(type, x, y) __cmp_once(max, type, x, y)
+#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
 
 /*
  * Do not check the array parameter using __must_be_array().
@@ -257,31 +275,6 @@
  */
 #define max_array(array, len) __minmax_array(max, array, len)
 
-/**
- * clamp_t - return a value clamped to a given range using a given type
- * @type: the type of variable to use
- * @val: current value
- * @lo: minimum allowable value
- * @hi: maximum allowable value
- *
- * 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))
-
-/**
- * clamp_val - return a value clamped to a given range using val's type
- * @val: current value
- * @lo: minimum allowable value
- * @hi: maximum allowable value
- *
- * This macro does no typechecking and uses temporary variables of whatever
- * type the input argument @val is.  This is useful when @val is an unsigned
- * 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)
-
 static inline bool in_range64(u64 val, u64 start, u64 len)
 {
 	return (val - start) < len;
Signature · 1 line
2.47.3
maintainer
#6 lore raw

Re: [PATCH 5/7 6.12.y] minmax.h: move all the clamp() definitions after the min/max() ones

Quoted 22 lines · Eliav Farber

From: David Laight <[email protected]>

[ Upstream commit c3939872ee4a6b8bdcd0e813c66823b31e6e26f7 ]

At some point the definitions for clamp() got added in the middle of the ones for min() and max(). Re-order the definitions so they are more sensibly grouped.

Cc Andy Shevchenko <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc Christoph Hellwig <[email protected]>
Cc Dan Carpenter <[email protected]>
Cc Jason A. Donenfeld <[email protected]>
Cc Jens Axboe <[email protected]>
Cc Lorenzo Stoakes <[email protected]>
Cc Mateusz Guzik <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc Pedro Falcato <[email protected]>
Quoted 3 lines
---
 include/linux/minmax.h | 109 +++++++++++++++++++----------------------
 1 file changed, 51 insertions(+), 58 deletions(-)

This diff looks odd. The upstream commit diffstat is:

include/linux/minmax.h | 131 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------------------------------------------------------------

1 file changed, 62 insertions(+), 69 deletions(-)

which does not match this diffstat, nor the diff itself.

But, if I backport the original commit myself, it matches up exactly with what you show here, which is odd.

diff is "fun", ugh...

Anyway, not a complaint, just something that others might note if they are comparing diffs here like I do.

thanks,

greg k-h

#7 lore raw

PATCH 6/7 minmax.h: simplify the variants of clamp()

In reply to Eliav Farber

From: David Laight <[email protected]>

[ 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.

Cc Andy Shevchenko <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc Christoph Hellwig <[email protected]>
Cc Dan Carpenter <[email protected]>
Cc Jason A. Donenfeld <[email protected]>
Cc Jens Axboe <[email protected]>
Cc Lorenzo Stoakes <[email protected]>
Cc Mateusz Guzik <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc Pedro Falcato <[email protected]>
---
 include/linux/minmax.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)
include/linux/minmax.h +12 -12
index 75fb7a6ad4c6..2bbdd5b5e07e 100644
@@ -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().
Signature · 1 line
2.47.3
#8 lore raw

PATCH 7/7 minmax.h: remove some #defines that are only expanded once

In reply to Eliav Farber

From: David Laight <[email protected]>

[ Upstream commit 2b97aaf74ed534fb838d09867d09a3ca5d795208 ]

The bodies of __signed_type_use() and __unsigned_type_use() are much the same size as their names - so put the bodies in the only line that expands them.

Similarly __signed_type() is defined separately for 64bit and then used exactly once just below.

Change the test for __signed_type from CONFIG_64BIT to one based on gcc defined macros so that the code is valid if it gets used outside of a kernel build.

Cc Andy Shevchenko <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc Christoph Hellwig <[email protected]>
Cc Dan Carpenter <[email protected]>
Cc Jason A. Donenfeld <[email protected]>
Cc Jens Axboe <[email protected]>
Cc Lorenzo Stoakes <[email protected]>
Cc Mateusz Guzik <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc Pedro Falcato <[email protected]>
---
 include/linux/minmax.h | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)
include/linux/minmax.h +6 -8
index 2bbdd5b5e07e..eaaf5c008e4d 100644
@@ -46,10 +46,8 @@
  * comparison, and these expressions only need to be careful to not cause
  * warnings for pointer use.
  */
-#define __signed_type_use(ux) (2 + __is_nonneg(ux))
-#define __unsigned_type_use(ux) (1 + 2 * (sizeof(ux) < 4))
 #define __sign_use(ux) (is_signed_type(typeof(ux)) ? \
-	__signed_type_use(ux) : __unsigned_type_use(ux))
+	(2 + __is_nonneg(ux)) : (1 + 2 * (sizeof(ux) < 4)))
 
 /*
  * Check whether a signed value is always non-negative.
@@ -57,7 +55,7 @@
  * A cast is needed to avoid any warnings from values that aren't signed
  * integer types (in which case the result doesn't matter).
  *
- * On 64-bit any integer or pointer type can safely be cast to 'long'.
+ * On 64-bit any integer or pointer type can safely be cast to 'long long'.
  * But on 32-bit we need to avoid warnings about casting pointers to integers
  * of different sizes without truncating 64-bit values so 'long' or 'long long'
  * must be used depending on the size of the value.
@@ -66,12 +64,12 @@
  * them, but we do not use s128 types in the kernel (we do use 'u128',
  * but they are handled by the !is_signed_type() case).
  */
-#ifdef CONFIG_64BIT
-  #define __signed_type(ux) long
+#if __SIZEOF_POINTER__ == __SIZEOF_LONG_LONG__
+#define __is_nonneg(ux) statically_true((long long)(ux) >= 0)
 #else
-  #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux) > 4, 1LL, 1L))
+#define __is_nonneg(ux) statically_true( \
+	(typeof(__builtin_choose_expr(sizeof(ux) > 4, 1LL, 1L)))(ux) >= 0)
 #endif
-#define __is_nonneg(ux) statically_true((__signed_type(ux))(ux) >= 0)
 
 #define __types_ok(ux, uy) \
 	(__sign_use(ux) & __sign_use(uy))
Signature · 1 line
2.47.3
maintainer
#9 lore raw
In reply to Eliav Farber
Quoted 6 lines · Eliav Farber

This series backports 7 patches to update minmax.h in the 6.12.y branch, aligning it with v6.17-rc7.

The ultimate goal is to synchronize all longterm branches so that they include the full set of minmax.h changes.

Quoted 8 lines

The key motivation is to bring in commit d03eba99f5bf ("minmax: allow min()/max()/clamp() if the arguments have the same signedness"), which is missing in older kernels.

In mainline, this change enables min()/max()/clamp() to accept mixed argument types, provided both have the same signedness. Without it, backported patches that use these forms may trigger compiler warnings, which escalate to build failures when -Werror is enabled.

All now queued up, thanks!

greg k-h