On 02.09.22 11:02, Kefeng Wang wrote:
>
> On 2022/9/2 16:42, David Hildenbrand wrote:
>> On 02.09.22 08:47, Kefeng Wang wrote:
>>> Add pageblock_aligned() and use it to simplify code.
>>>
>>> Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
>>> ---
>> [...]
>>
>>> - unsigned long nr_pgmask = pageblock_nr_pages - 1;
>>> int nid = zone_to_nid(zone);
>>> unsigned long nr_pages = 0;
>>> int zid = zone_idx(zone);
>>> @@ -1977,7 +1974,7 @@ static unsigned long __init deferred_init_pages(struct zone *zone,
>>> if (!deferred_pfn_valid(pfn)) {
>>> page = NULL;
>>> continue;
>>> - } else if (!page || !(pfn & nr_pgmask)) {
>> I didn't sleep too well this night and am tired, please tell me why I'm
>> wrong :)
> Wish you have a good reset :)
Thanks, the headache isn't helping :D
>> "pfn & (pageblock_nr_pages - 1)" is true if the pageblock is not aligned
>>
>> E.g., pfn = 1, pageblock_nr_pages = 512
>>
>> pfn & (pageblock_nr_pages - 1)
>> -> 1 & (512 - 1)
>> -> 1 & 511
>> -> true
>>
>> "!(pfn & (pageblock_nr_pages - 1))" is true if the pageblock is aligned
>> -> !(true)
>> -> false
>>
>>
>> However, "!pageblock_aligned(1)" = true
>>
>>
>>> + } else if (!page || !pageblock_aligned(pfn)) {
>
> pageblock_aligned(pfn) IS_ALIGNED((unsigned long)(pfn), pageblock_nr_pages)
>
> #define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0) (((pfn) &
> (pageblock_nr_pages - 1)) == 0) -> ((1 & 512 -1) == 0) -> ((1 & 511) ==
> 0) -> ((511) == 0) -> false
> right ?
yes ... and inverting that would give you "true", which is not what we want?
Again, sorry if I'm wrong ...
--
Thanks,
David / dhildenb
