Messages in this thread | | | Date | Sun, 22 Dec 2013 17:17:13 +0800 | From | Chen Gang <> | Subject | Re: [PATCH] drivers: target: target_core_mod: use div64_u64_rem() instead of operator '%' for u64 |
| |
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@gmail.com> >> --- >> 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
| |