* [PATCH] mm/slab_common: use helper function is_power_of_2()
@ 2022-02-17 9:16 Miaohe Lin
2022-02-17 9:23 ` Vlastimil Babka
0 siblings, 1 reply; 5+ messages in thread
From: Miaohe Lin @ 2022-02-17 9:16 UTC (permalink / raw)
To: akpm, cl, penberg, rientjes, iamjoonsoo.kim, vbabka
Cc: linux-mm, linux-kernel, linmiaohe
Use helper function is_power_of_2() to check if KMALLOC_MIN_SIZE is power
of two. Minor readability improvement.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
mm/slab_common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 23f2ab0713b7..6ee64d6208b3 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -807,7 +807,7 @@ void __init setup_kmalloc_cache_index_table(void)
unsigned int i;
BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
- (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
+ !is_power_of_2(KMALLOC_MIN_SIZE));
for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
unsigned int elem = size_index_elem(i);
--
2.23.0
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm/slab_common: use helper function is_power_of_2()
2022-02-17 9:16 [PATCH] mm/slab_common: use helper function is_power_of_2() Miaohe Lin
@ 2022-02-17 9:23 ` Vlastimil Babka
2022-02-17 10:44 ` Miaohe Lin
0 siblings, 1 reply; 5+ messages in thread
From: Vlastimil Babka @ 2022-02-17 9:23 UTC (permalink / raw)
To: Miaohe Lin, akpm, cl, penberg, rientjes, iamjoonsoo.kim
Cc: linux-mm, linux-kernel
On 2/17/22 10:16, Miaohe Lin wrote:
> Use helper function is_power_of_2() to check if KMALLOC_MIN_SIZE is power
> of two. Minor readability improvement.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
We can try, but in case some compiler will no longer able to perform the
check at build-time (although is_power_of_2() looks sufficiently trivial
too), we'll have to revert it.
> ---
> mm/slab_common.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 23f2ab0713b7..6ee64d6208b3 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -807,7 +807,7 @@ void __init setup_kmalloc_cache_index_table(void)
> unsigned int i;
>
> BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
> - (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
> + !is_power_of_2(KMALLOC_MIN_SIZE));
>
> for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
> unsigned int elem = size_index_elem(i);
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm/slab_common: use helper function is_power_of_2()
2022-02-17 9:23 ` Vlastimil Babka
@ 2022-02-17 10:44 ` Miaohe Lin
2022-02-17 17:04 ` Vlastimil Babka
0 siblings, 1 reply; 5+ messages in thread
From: Miaohe Lin @ 2022-02-17 10:44 UTC (permalink / raw)
To: Vlastimil Babka
Cc: linux-mm, linux-kernel, Andrew Morton, Christoph Lameter,
penberg, rientjes, iamjoonsoo.kim
On 2022/2/17 17:23, Vlastimil Babka wrote:
> On 2/17/22 10:16, Miaohe Lin wrote:
>> Use helper function is_power_of_2() to check if KMALLOC_MIN_SIZE is power
>> of two. Minor readability improvement.
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>
> We can try, but in case some compiler will no longer able to perform the
> check at build-time (although is_power_of_2() looks sufficiently trivial
> too), we'll have to revert it.
I see. I checked the compiler in my env but there might be some compilers can't
perform the check at build-time.
Many thanks for your reply.
>
>> ---
>> mm/slab_common.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/slab_common.c b/mm/slab_common.c
>> index 23f2ab0713b7..6ee64d6208b3 100644
>> --- a/mm/slab_common.c
>> +++ b/mm/slab_common.c
>> @@ -807,7 +807,7 @@ void __init setup_kmalloc_cache_index_table(void)
>> unsigned int i;
>>
>> BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
>> - (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
>> + !is_power_of_2(KMALLOC_MIN_SIZE));
>>
>> for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
>> unsigned int elem = size_index_elem(i);
>
> .
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm/slab_common: use helper function is_power_of_2()
2022-02-17 10:44 ` Miaohe Lin
@ 2022-02-17 17:04 ` Vlastimil Babka
2022-02-18 1:15 ` Miaohe Lin
0 siblings, 1 reply; 5+ messages in thread
From: Vlastimil Babka @ 2022-02-17 17:04 UTC (permalink / raw)
To: Miaohe Lin
Cc: linux-mm, linux-kernel, Andrew Morton, Christoph Lameter,
penberg, rientjes, iamjoonsoo.kim
On 2/17/22 11:44, Miaohe Lin wrote:
> On 2022/2/17 17:23, Vlastimil Babka wrote:
>> On 2/17/22 10:16, Miaohe Lin wrote:
>>> Use helper function is_power_of_2() to check if KMALLOC_MIN_SIZE is power
>>> of two. Minor readability improvement.
>>>
>>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>>
>> We can try, but in case some compiler will no longer able to perform the
>> check at build-time (although is_power_of_2() looks sufficiently trivial
>> too), we'll have to revert it.
>
> I see. I checked the compiler in my env but there might be some compilers can't
> perform the check at build-time.
I'll add this to the slab tree and linux-next and we'll see if wider testing
uncovers such compilers. Should be unlikely.
> Many thanks for your reply.
>
>>
>>> ---
>>> mm/slab_common.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/mm/slab_common.c b/mm/slab_common.c
>>> index 23f2ab0713b7..6ee64d6208b3 100644
>>> --- a/mm/slab_common.c
>>> +++ b/mm/slab_common.c
>>> @@ -807,7 +807,7 @@ void __init setup_kmalloc_cache_index_table(void)
>>> unsigned int i;
>>>
>>> BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
>>> - (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
>>> + !is_power_of_2(KMALLOC_MIN_SIZE));
>>>
>>> for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
>>> unsigned int elem = size_index_elem(i);
>>
>> .
>>
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm/slab_common: use helper function is_power_of_2()
2022-02-17 17:04 ` Vlastimil Babka
@ 2022-02-18 1:15 ` Miaohe Lin
0 siblings, 0 replies; 5+ messages in thread
From: Miaohe Lin @ 2022-02-18 1:15 UTC (permalink / raw)
To: Vlastimil Babka
Cc: linux-mm, linux-kernel, Andrew Morton, Christoph Lameter,
penberg, rientjes, iamjoonsoo.kim
On 2022/2/18 1:04, Vlastimil Babka wrote:
> On 2/17/22 11:44, Miaohe Lin wrote:
>> On 2022/2/17 17:23, Vlastimil Babka wrote:
>>> On 2/17/22 10:16, Miaohe Lin wrote:
>>>> Use helper function is_power_of_2() to check if KMALLOC_MIN_SIZE is power
>>>> of two. Minor readability improvement.
>>>>
>>>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>>>
>>> We can try, but in case some compiler will no longer able to perform the
>>> check at build-time (although is_power_of_2() looks sufficiently trivial
>>> too), we'll have to revert it.
>>
>> I see. I checked the compiler in my env but there might be some compilers can't
>> perform the check at build-time.
>
> I'll add this to the slab tree and linux-next and we'll see if wider testing
> uncovers such compilers. Should be unlikely.
Many thanks! :)
>
>> Many thanks for your reply.
>>
>>>
>>>> ---
>>>> mm/slab_common.c | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/mm/slab_common.c b/mm/slab_common.c
>>>> index 23f2ab0713b7..6ee64d6208b3 100644
>>>> --- a/mm/slab_common.c
>>>> +++ b/mm/slab_common.c
>>>> @@ -807,7 +807,7 @@ void __init setup_kmalloc_cache_index_table(void)
>>>> unsigned int i;
>>>>
>>>> BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
>>>> - (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
>>>> + !is_power_of_2(KMALLOC_MIN_SIZE));
>>>>
>>>> for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
>>>> unsigned int elem = size_index_elem(i);
>>>
>>> .
>>>
>>
>
> .
>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-02-18 1:15 UTC | newest]
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2022-02-17 9:16 [PATCH] mm/slab_common: use helper function is_power_of_2() Miaohe Lin
2022-02-17 9:23 ` Vlastimil Babka
2022-02-17 10:44 ` Miaohe Lin
2022-02-17 17:04 ` Vlastimil Babka
2022-02-18 1:15 ` Miaohe Lin
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