On 12/22/2013 10:56 AM, Nicholas A. Bellinger wrote:
> Hi Chen,
>
> On Sat, 2013-12-21 at 10:08 +0800, Chen Gang wrote:
>> In kernel, need use div64_u64_rem() instead of operator '%' for u64, or
>> can not pass compiling (with allmodconfig under metag):
>>
>> MODPOST 2909 modules
>> ERROR: "__umoddi3" [drivers/target/target_core_mod.ko] undefined!
>>
>> Also need u64 type cast for u32 variable multiply u32 variable, or will
>> cause type overflow issue.
>>
>>
>> Signed-off-by: Chen Gang <gang.chen.5i5j@xxxxxxxxx>
>> ---
>> drivers/target/target_core_alua.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>
> FYI, this unsigned long long division in core_alua_state_lba_dependent()
> was fixed for 32-bit in linux-next >= 12192013 code.
>
OK, thanks.
The related fix patch changed "start_lba = lba % ..." to "start_lba =
lba / ...", and also assumed "segment_size * segment_mult" is still
within u32 (can not cause type over flow).
I guess the original author already knew about them, and intended to do
like that (if not, please let me know, thanks).
> Regardless, thanks for your patch.
>
Thank you too.
> --nab
>
>> diff --git a/drivers/target/target_core_alua.c b/drivers/target/target_core_alua.c
>> index dc0d399..ff2aadc 100644
>> --- a/drivers/target/target_core_alua.c
>> +++ b/drivers/target/target_core_alua.c
>> @@ -489,7 +489,8 @@ static inline int core_alua_state_lba_dependent(
>> u64 first_lba = map->lba_map_first_lba;
>>
>> if (segment_mult) {
>> - start_lba = lba % (segment_size * segment_mult);
>> + u64 tmp = (u64)segment_size * segment_mult;
>> + div64_u64_rem(lba, tmp, &start_lba);
>> last_lba = first_lba + segment_size - 1;
>> if (start_lba >= first_lba &&
>> start_lba <= last_lba) {
>
>
--
Chen Gang
Open, share and attitude like air, water and life which God blessed
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