diff mbox series

[v1] kernel.h: Split out mathematical helpers

Message ID 20201028173212.41768-1-andriy.shevchenko@linux.intel.com
State New
Headers show
Series [v1] kernel.h: Split out mathematical helpers | expand

Commit Message

Andy Shevchenko Oct. 28, 2020, 5:32 p.m. UTC
kernel.h is being used as a dump for all kinds of stuff for a long time.
Here is the attempt to start cleaning it up by splitting out mathematical
helpers.

At the same time convert users in header and lib folder to use new header.
Though for time being include new header back to kernel.h to avoid twisted
indirected includes for existing users.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 fs/nfs/callback_proc.c        |   5 +
 include/linux/bitops.h        |  11 ++-
 include/linux/dcache.h        |   1 +
 include/linux/iommu-helper.h  |   4 +-
 include/linux/kernel.h        | 173 +--------------------------------
 include/linux/math.h          | 177 ++++++++++++++++++++++++++++++++++
 include/linux/rcu_node_tree.h |   2 +
 include/linux/units.h         |   2 +-
 lib/errname.c                 |   1 +
 lib/errseq.c                  |   1 +
 lib/find_bit.c                |   3 +-
 lib/math/div64.c              |   3 +-
 lib/math/int_pow.c            |   2 +-
 lib/math/int_sqrt.c           |   3 +-
 lib/math/reciprocal_div.c     |   9 +-
 15 files changed, 214 insertions(+), 183 deletions(-)
 create mode 100644 include/linux/math.h
diff mbox series

Patch

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index e61dbc9b86ae..f7786e00a6a7 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -6,10 +6,15 @@ 
  *
  * NFSv4 callback procedures
  */
+
+#include <linux/errno.h>
+#include <linux/math.h>
 #include <linux/nfs4.h>
 #include <linux/nfs_fs.h>
 #include <linux/slab.h>
 #include <linux/rcupdate.h>
+#include <linux/types.h>
+
 #include "nfs4_fs.h"
 #include "callback.h"
 #include "delegation.h"
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 5ace312bedfa..aad53f399983 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -1,9 +1,12 @@ 
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _LINUX_BITOPS_H
 #define _LINUX_BITOPS_H
+
 #include <asm/types.h>
 #include <linux/bits.h>
 
+#include <uapi/linux/kernel.h>
+
 /* Set bits in the first 'n' bytes when loaded from memory */
 #ifdef __LITTLE_ENDIAN
 #  define aligned_byte_mask(n) ((1UL << 8*(n))-1)
@@ -12,10 +15,10 @@ 
 #endif
 
 #define BITS_PER_TYPE(type)	(sizeof(type) * BITS_PER_BYTE)
-#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
-#define BITS_TO_U64(nr)		DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
-#define BITS_TO_U32(nr)		DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
-#define BITS_TO_BYTES(nr)	DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
+#define BITS_TO_LONGS(nr)	__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
+#define BITS_TO_U64(nr)		__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
+#define BITS_TO_U32(nr)		__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
+#define BITS_TO_BYTES(nr)	__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
 
 extern unsigned int __sw_hweight8(unsigned int w);
 extern unsigned int __sw_hweight16(unsigned int w);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index ffcb7b79f151..81033567f250 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -4,6 +4,7 @@ 
 
 #include <linux/atomic.h>
 #include <linux/list.h>
+#include <linux/math.h>
 #include <linux/rculist.h>
 #include <linux/rculist_bl.h>
 #include <linux/spinlock.h>
diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
index 70d01edcbf8b..74be34f3a20a 100644
--- a/include/linux/iommu-helper.h
+++ b/include/linux/iommu-helper.h
@@ -3,7 +3,9 @@ 
 #define _LINUX_IOMMU_HELPER_H
 
 #include <linux/bug.h>
-#include <linux/kernel.h>
+#include <linux/log2.h>
+#include <linux/math.h>
+#include <linux/types.h>
 
 static inline unsigned long iommu_device_max_index(unsigned long size,
 						   unsigned long offset,
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 2f05e9128201..f97ab3283a8b 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -2,7 +2,6 @@ 
 #ifndef _LINUX_KERNEL_H
 #define _LINUX_KERNEL_H
 
-
 #include <stdarg.h>
 #include <linux/limits.h>
 #include <linux/linkage.h>
@@ -11,12 +10,14 @@ 
 #include <linux/compiler.h>
 #include <linux/bitops.h>
 #include <linux/log2.h>
+#include <linux/math.h>
 #include <linux/minmax.h>
 #include <linux/typecheck.h>
 #include <linux/printk.h>
 #include <linux/build_bug.h>
+
 #include <asm/byteorder.h>
-#include <asm/div64.h>
+
 #include <uapi/linux/kernel.h>
 
 #define STACK_MAGIC	0xdeadbeef
@@ -54,125 +55,11 @@ 
 }					\
 )
 
-/*
- * This looks more complex than it should be. But we need to
- * get the type for the ~ right in round_down (it needs to be
- * as wide as the result!), and we want to evaluate the macro
- * arguments just once each.
- */
-#define __round_mask(x, y) ((__typeof__(x))((y)-1))
-/**
- * round_up - round up to next specified power of 2
- * @x: the value to round
- * @y: multiple to round up to (must be a power of 2)
- *
- * Rounds @x up to next multiple of @y (which must be a power of 2).
- * To perform arbitrary rounding up, use roundup() below.
- */
-#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
-/**
- * round_down - round down to next specified power of 2
- * @x: the value to round
- * @y: multiple to round down to (must be a power of 2)
- *
- * Rounds @x down to next multiple of @y (which must be a power of 2).
- * To perform arbitrary rounding down, use rounddown() below.
- */
-#define round_down(x, y) ((x) & ~__round_mask(x, y))
-
 #define typeof_member(T, m)	typeof(((T*)0)->m)
 
-#define DIV_ROUND_UP __KERNEL_DIV_ROUND_UP
-
-#define DIV_ROUND_DOWN_ULL(ll, d) \
-	({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })
-
-#define DIV_ROUND_UP_ULL(ll, d) \
-	DIV_ROUND_DOWN_ULL((unsigned long long)(ll) + (d) - 1, (d))
-
-#if BITS_PER_LONG == 32
-# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
-#else
-# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
-#endif
-
-/**
- * roundup - round up to the next specified multiple
- * @x: the value to up
- * @y: multiple to round up to
- *
- * Rounds @x up to next multiple of @y. If @y will always be a power
- * of 2, consider using the faster round_up().
- */
-#define roundup(x, y) (					\
-{							\
-	typeof(y) __y = y;				\
-	(((x) + (__y - 1)) / __y) * __y;		\
-}							\
-)
-/**
- * rounddown - round down to next specified multiple
- * @x: the value to round
- * @y: multiple to round down to
- *
- * Rounds @x down to next multiple of @y. If @y will always be a power
- * of 2, consider using the faster round_down().
- */
-#define rounddown(x, y) (				\
-{							\
-	typeof(x) __x = (x);				\
-	__x - (__x % (y));				\
-}							\
-)
-
-/*
- * Divide positive or negative dividend by positive or negative divisor
- * and round to closest integer. Result is undefined for negative
- * divisors if the dividend variable type is unsigned and for negative
- * dividends if the divisor variable type is unsigned.
- */
-#define DIV_ROUND_CLOSEST(x, divisor)(			\
-{							\
-	typeof(x) __x = x;				\
-	typeof(divisor) __d = divisor;			\
-	(((typeof(x))-1) > 0 ||				\
-	 ((typeof(divisor))-1) > 0 ||			\
-	 (((__x) > 0) == ((__d) > 0))) ?		\
-		(((__x) + ((__d) / 2)) / (__d)) :	\
-		(((__x) - ((__d) / 2)) / (__d));	\
-}							\
-)
-/*
- * Same as above but for u64 dividends. divisor must be a 32-bit
- * number.
- */
-#define DIV_ROUND_CLOSEST_ULL(x, divisor)(		\
-{							\
-	typeof(divisor) __d = divisor;			\
-	unsigned long long _tmp = (x) + (__d) / 2;	\
-	do_div(_tmp, __d);				\
-	_tmp;						\
-}							\
-)
-
-/*
- * Multiplies an integer by a fraction, while avoiding unnecessary
- * overflow or loss of precision.
- */
-#define mult_frac(x, numer, denom)(			\
-{							\
-	typeof(x) quot = (x) / (denom);			\
-	typeof(x) rem  = (x) % (denom);			\
-	(quot * (numer)) + ((rem * (numer)) / (denom));	\
-}							\
-)
-
-
 #define _RET_IP_		(unsigned long)__builtin_return_address(0)
 #define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
 
-#define sector_div(a, b) do_div(a, b)
-
 /**
  * upper_32_bits - return bits 32-63 of a number
  * @n: the number we're accessing
@@ -265,48 +152,6 @@  extern void __cant_sleep(const char *file, int line, int preempt_offset);
 # define cant_migrate()		do { } while (0)
 #endif
 
-/**
- * abs - return absolute value of an argument
- * @x: the value.  If it is unsigned type, it is converted to signed type first.
- *     char is treated as if it was signed (regardless of whether it really is)
- *     but the macro's return type is preserved as char.
- *
- * Return: an absolute value of x.
- */
-#define abs(x)	__abs_choose_expr(x, long long,				\
-		__abs_choose_expr(x, long,				\
-		__abs_choose_expr(x, int,				\
-		__abs_choose_expr(x, short,				\
-		__abs_choose_expr(x, char,				\
-		__builtin_choose_expr(					\
-			__builtin_types_compatible_p(typeof(x), char),	\
-			(char)({ signed char __x = (x); __x<0?-__x:__x; }), \
-			((void)0)))))))
-
-#define __abs_choose_expr(x, type, other) __builtin_choose_expr(	\
-	__builtin_types_compatible_p(typeof(x),   signed type) ||	\
-	__builtin_types_compatible_p(typeof(x), unsigned type),		\
-	({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
-
-/**
- * reciprocal_scale - "scale" a value into range [0, ep_ro)
- * @val: value
- * @ep_ro: right open interval endpoint
- *
- * Perform a "reciprocal multiplication" in order to "scale" a value into
- * range [0, @ep_ro), where the upper interval endpoint is right-open.
- * This is useful, e.g. for accessing a index of an array containing
- * @ep_ro elements, for example. Think of it as sort of modulus, only that
- * the result isn't that of modulo. ;) Note that if initial input is a
- * small value, then result will return 0.
- *
- * Return: a result based on @val in interval [0, @ep_ro).
- */
-static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
-{
-	return (u32)(((u64) val * ep_ro) >> 32);
-}
-
 #if defined(CONFIG_MMU) && \
 	(defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
 #define might_fault() __might_fault(__FILE__, __LINE__)
@@ -508,18 +353,6 @@  extern int __kernel_text_address(unsigned long addr);
 extern int kernel_text_address(unsigned long addr);
 extern int func_ptr_is_kernel_text(void *ptr);
 
-u64 int_pow(u64 base, unsigned int exp);
-unsigned long int_sqrt(unsigned long);
-
-#if BITS_PER_LONG < 64
-u32 int_sqrt64(u64 x);
-#else
-static inline u32 int_sqrt64(u64 x)
-{
-	return (u32)int_sqrt(x);
-}
-#endif
-
 #ifdef CONFIG_SMP
 extern unsigned int sysctl_oops_all_cpu_backtrace;
 #else
diff --git a/include/linux/math.h b/include/linux/math.h
new file mode 100644
index 000000000000..53674a327e39
--- /dev/null
+++ b/include/linux/math.h
@@ -0,0 +1,177 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_MATH_H
+#define _LINUX_MATH_H
+
+#include <asm/div64.h>
+#include <uapi/linux/kernel.h>
+
+/*
+ * This looks more complex than it should be. But we need to
+ * get the type for the ~ right in round_down (it needs to be
+ * as wide as the result!), and we want to evaluate the macro
+ * arguments just once each.
+ */
+#define __round_mask(x, y) ((__typeof__(x))((y)-1))
+
+/**
+ * round_up - round up to next specified power of 2
+ * @x: the value to round
+ * @y: multiple to round up to (must be a power of 2)
+ *
+ * Rounds @x up to next multiple of @y (which must be a power of 2).
+ * To perform arbitrary rounding up, use roundup() below.
+ */
+#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
+
+/**
+ * round_down - round down to next specified power of 2
+ * @x: the value to round
+ * @y: multiple to round down to (must be a power of 2)
+ *
+ * Rounds @x down to next multiple of @y (which must be a power of 2).
+ * To perform arbitrary rounding down, use rounddown() below.
+ */
+#define round_down(x, y) ((x) & ~__round_mask(x, y))
+
+#define DIV_ROUND_UP __KERNEL_DIV_ROUND_UP
+
+#define DIV_ROUND_DOWN_ULL(ll, d) \
+	({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })
+
+#define DIV_ROUND_UP_ULL(ll, d) \
+	DIV_ROUND_DOWN_ULL((unsigned long long)(ll) + (d) - 1, (d))
+
+#if BITS_PER_LONG == 32
+# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
+#else
+# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
+#endif
+
+/**
+ * roundup - round up to the next specified multiple
+ * @x: the value to up
+ * @y: multiple to round up to
+ *
+ * Rounds @x up to next multiple of @y. If @y will always be a power
+ * of 2, consider using the faster round_up().
+ */
+#define roundup(x, y) (					\
+{							\
+	typeof(y) __y = y;				\
+	(((x) + (__y - 1)) / __y) * __y;		\
+}							\
+)
+/**
+ * rounddown - round down to next specified multiple
+ * @x: the value to round
+ * @y: multiple to round down to
+ *
+ * Rounds @x down to next multiple of @y. If @y will always be a power
+ * of 2, consider using the faster round_down().
+ */
+#define rounddown(x, y) (				\
+{							\
+	typeof(x) __x = (x);				\
+	__x - (__x % (y));				\
+}							\
+)
+
+/*
+ * Divide positive or negative dividend by positive or negative divisor
+ * and round to closest integer. Result is undefined for negative
+ * divisors if the dividend variable type is unsigned and for negative
+ * dividends if the divisor variable type is unsigned.
+ */
+#define DIV_ROUND_CLOSEST(x, divisor)(			\
+{							\
+	typeof(x) __x = x;				\
+	typeof(divisor) __d = divisor;			\
+	(((typeof(x))-1) > 0 ||				\
+	 ((typeof(divisor))-1) > 0 ||			\
+	 (((__x) > 0) == ((__d) > 0))) ?		\
+		(((__x) + ((__d) / 2)) / (__d)) :	\
+		(((__x) - ((__d) / 2)) / (__d));	\
+}							\
+)
+/*
+ * Same as above but for u64 dividends. divisor must be a 32-bit
+ * number.
+ */
+#define DIV_ROUND_CLOSEST_ULL(x, divisor)(		\
+{							\
+	typeof(divisor) __d = divisor;			\
+	unsigned long long _tmp = (x) + (__d) / 2;	\
+	do_div(_tmp, __d);				\
+	_tmp;						\
+}							\
+)
+
+/*
+ * Multiplies an integer by a fraction, while avoiding unnecessary
+ * overflow or loss of precision.
+ */
+#define mult_frac(x, numer, denom)(			\
+{							\
+	typeof(x) quot = (x) / (denom);			\
+	typeof(x) rem  = (x) % (denom);			\
+	(quot * (numer)) + ((rem * (numer)) / (denom));	\
+}							\
+)
+
+#define sector_div(a, b) do_div(a, b)
+
+/**
+ * abs - return absolute value of an argument
+ * @x: the value.  If it is unsigned type, it is converted to signed type first.
+ *     char is treated as if it was signed (regardless of whether it really is)
+ *     but the macro's return type is preserved as char.
+ *
+ * Return: an absolute value of x.
+ */
+#define abs(x)	__abs_choose_expr(x, long long,				\
+		__abs_choose_expr(x, long,				\
+		__abs_choose_expr(x, int,				\
+		__abs_choose_expr(x, short,				\
+		__abs_choose_expr(x, char,				\
+		__builtin_choose_expr(					\
+			__builtin_types_compatible_p(typeof(x), char),	\
+			(char)({ signed char __x = (x); __x<0?-__x:__x; }), \
+			((void)0)))))))
+
+#define __abs_choose_expr(x, type, other) __builtin_choose_expr(	\
+	__builtin_types_compatible_p(typeof(x),   signed type) ||	\
+	__builtin_types_compatible_p(typeof(x), unsigned type),		\
+	({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
+
+/**
+ * reciprocal_scale - "scale" a value into range [0, ep_ro)
+ * @val: value
+ * @ep_ro: right open interval endpoint
+ *
+ * Perform a "reciprocal multiplication" in order to "scale" a value into
+ * range [0, @ep_ro), where the upper interval endpoint is right-open.
+ * This is useful, e.g. for accessing a index of an array containing
+ * @ep_ro elements, for example. Think of it as sort of modulus, only that
+ * the result isn't that of modulo. ;) Note that if initial input is a
+ * small value, then result will return 0.
+ *
+ * Return: a result based on @val in interval [0, @ep_ro).
+ */
+static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
+{
+	return (u32)(((u64) val * ep_ro) >> 32);
+}
+
+u64 int_pow(u64 base, unsigned int exp);
+unsigned long int_sqrt(unsigned long);
+
+#if BITS_PER_LONG < 64
+u32 int_sqrt64(u64 x);
+#else
+static inline u32 int_sqrt64(u64 x)
+{
+	return (u32)int_sqrt(x);
+}
+#endif
+
+#endif	/* _LINUX_MATH_H */
diff --git a/include/linux/rcu_node_tree.h b/include/linux/rcu_node_tree.h
index b8e094b125ee..78feb8ba7358 100644
--- a/include/linux/rcu_node_tree.h
+++ b/include/linux/rcu_node_tree.h
@@ -20,6 +20,8 @@ 
 #ifndef __LINUX_RCU_NODE_TREE_H
 #define __LINUX_RCU_NODE_TREE_H
 
+#include <linux/math.h>
+
 /*
  * Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and
  * CONFIG_RCU_FANOUT_LEAF.
diff --git a/include/linux/units.h b/include/linux/units.h
index aaf716364ec3..5c115c809507 100644
--- a/include/linux/units.h
+++ b/include/linux/units.h
@@ -2,7 +2,7 @@ 
 #ifndef _LINUX_UNITS_H
 #define _LINUX_UNITS_H
 
-#include <linux/kernel.h>
+#include <linux/math.h>
 
 #define ABSOLUTE_ZERO_MILLICELSIUS -273150
 
diff --git a/lib/errname.c b/lib/errname.c
index 0c4d3e66170e..05cbf731545f 100644
--- a/lib/errname.c
+++ b/lib/errname.c
@@ -3,6 +3,7 @@ 
 #include <linux/errno.h>
 #include <linux/errname.h>
 #include <linux/kernel.h>
+#include <linux/math.h>
 
 /*
  * Ensure these tables do not accidentally become gigantic if some
diff --git a/lib/errseq.c b/lib/errseq.c
index 81f9e33aa7e7..93e9b94358dc 100644
--- a/lib/errseq.c
+++ b/lib/errseq.c
@@ -3,6 +3,7 @@ 
 #include <linux/bug.h>
 #include <linux/atomic.h>
 #include <linux/errseq.h>
+#include <linux/log2.h>
 
 /*
  * An errseq_t is a way of recording errors in one place, and allowing any
diff --git a/lib/find_bit.c b/lib/find_bit.c
index 6333a394465a..df67a6ac3a8b 100644
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -15,8 +15,9 @@ 
 #include <linux/bitops.h>
 #include <linux/bitmap.h>
 #include <linux/export.h>
-#include <linux/kernel.h>
+#include <linux/math.h>
 #include <linux/minmax.h>
+#include <linux/swab.h>
 
 #if !defined(find_next_bit) || !defined(find_next_zero_bit) ||			\
 	!defined(find_next_bit_le) || !defined(find_next_zero_bit_le) ||	\
diff --git a/lib/math/div64.c b/lib/math/div64.c
index 3952a07130d8..dcc826c40ca1 100644
--- a/lib/math/div64.c
+++ b/lib/math/div64.c
@@ -18,8 +18,9 @@ 
  * or by defining a preprocessor macro in arch/include/asm/div64.h.
  */
 
+#include <linux/bitops.h>
 #include <linux/export.h>
-#include <linux/kernel.h>
+#include <linux/math.h>
 #include <linux/math64.h>
 
 /* Not needed on 64bit architectures */
diff --git a/lib/math/int_pow.c b/lib/math/int_pow.c
index 622fc1ab3c74..0cf426e69bda 100644
--- a/lib/math/int_pow.c
+++ b/lib/math/int_pow.c
@@ -6,7 +6,7 @@ 
  */
 
 #include <linux/export.h>
-#include <linux/kernel.h>
+#include <linux/math.h>
 #include <linux/types.h>
 
 /**
diff --git a/lib/math/int_sqrt.c b/lib/math/int_sqrt.c
index 30e0f9770f88..a8170bb9142f 100644
--- a/lib/math/int_sqrt.c
+++ b/lib/math/int_sqrt.c
@@ -6,9 +6,10 @@ 
  *  square root from Guy L. Steele.
  */
 
-#include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/bitops.h>
+#include <linux/limits.h>
+#include <linux/math.h>
 
 /**
  * int_sqrt - computes the integer square root
diff --git a/lib/math/reciprocal_div.c b/lib/math/reciprocal_div.c
index 32436dd4171e..6cb4adbb81d2 100644
--- a/lib/math/reciprocal_div.c
+++ b/lib/math/reciprocal_div.c
@@ -1,10 +1,13 @@ 
 // SPDX-License-Identifier: GPL-2.0
+#include <linux/bitops.h>
 #include <linux/bug.h>
-#include <linux/kernel.h>
-#include <asm/div64.h>
-#include <linux/reciprocal_div.h>
 #include <linux/export.h>
+#include <linux/limits.h>
+#include <linux/math.h>
 #include <linux/minmax.h>
+#include <linux/types.h>
+
+#include <linux/reciprocal_div.h>
 
 /*
  * For a description of the algorithm please have a look at