2019-01-27 20:34:57

by Florian La Roche

Subject: [PATCH v2 1/1] int_sqrt() adjustments

Add __attribute_const__ and use normal ints for the right param of "<<".

Signed-off-by: Florian La Roche <[email protected]>
---
include/linux/kernel.h | 4 ++--
lib/int_sqrt.c | 8 ++++----
2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 8f0e68e250a7..df03a3cca309 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -513,10 +513,10 @@ 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);

-unsigned long int_sqrt(unsigned long);
+__attribute_const__ unsigned long int_sqrt(unsigned long);

#if BITS_PER_LONG < 64
-u32 int_sqrt64(u64 x);
+__attribute_const__ u32 int_sqrt64(u64 x);
#else
static inline u32 int_sqrt64(u64 x)
{
diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c
index 30e0f9770f88..fd249238fd31 100644
--- a/lib/int_sqrt.c
+++ b/lib/int_sqrt.c
@@ -16,14 +16,14 @@
*
* Computes: floor(sqrt(x))
*/
-unsigned long int_sqrt(unsigned long x)
+__attribute_const__ unsigned long int_sqrt(unsigned long x)
{
unsigned long b, m, y = 0;

if (x <= 1)
return x;

- m = 1UL << (__fls(x) & ~1UL);
+ m = 1UL << (__fls(x) & ~1);
while (m != 0) {
b = y + m;
y >>= 1;
@@ -45,14 +45,14 @@ EXPORT_SYMBOL(int_sqrt);
* is expected.
* @x: 64bit integer of which to calculate the sqrt
*/
-u32 int_sqrt64(u64 x)
+__attribute_const__ u32 int_sqrt64(u64 x)
{
u64 b, m, y = 0;

if (x <= ULONG_MAX)
return int_sqrt((unsigned long) x);

- m = 1ULL << ((fls64(x) - 1) & ~1ULL);
+ m = 1ULL << ((fls64(x) - 1) & ~1);
while (m != 0) {
b = y + m;
y >>= 1;
--
2.17.1

2019-01-27 20:50:08

by Joe Perches

Subject: Re: [PATCH v2 1/1] int_sqrt() adjustments

On Sun, 2019-01-27 at 21:32 +0100, Florian La Roche wrote:
> Add __attribute_const__ and use normal ints for the right param of "<<".
[]
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
[]
> @@ -513,10 +513,10 @@ 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);
>
> -unsigned long int_sqrt(unsigned long);
> +__attribute_const__ unsigned long int_sqrt(unsigned long);

This might as well return u32 to be consistent with int_sqrt64

2019-01-27 21:31:32

by Florian La Roche

Subject: Re: [PATCH v2 1/1] int_sqrt() adjustments

Hello Joe,

sending in a new patch with u32 as return value and some adjusted
callers of int_sqrt().

best regards,

Florian La Roche