Messages in this thread | | | Date | Thu, 5 Nov 2015 21:56:42 +0200 | Subject | Re: [PATCH 3/4] scsi: fix compiler warning for sg | From | Andy Shevchenko <> |
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On Thu, Nov 5, 2015 at 9:31 PM, Andy Shevchenko <andy.shevchenko@gmail.com> wrote: > On Thu, Nov 5, 2015 at 8:32 PM, Sinan Kaya <okaya@codeaurora.org> wrote: >> On 11/5/2015 1:07 PM, Andy Shevchenko wrote: > >> Let's try again. >> >> static inline u64 mult_frac64(u64 x, u32 numer, u32 denom) { >> u64 rem = x % denom; >> u64 quot = do_div(x, denom); >> u64 mul = rem * numer; >> >> return (quot * numer) + do_div(mul, denom); >> } > > First of all why not to put this to generic header? We have math64.h > and kernel.h. > Might be a good idea (needs to check current users) to move mult_frac > to math64.h. > > Then, x % y is already a problem. After all, you seems messed quot and > remainder. > > What about something like > > #if BITS_PER_LONG == 64 > > #define mult_frac64(x,n,d) mult_frac(x,n,d) > > #else > > static inline u64 mult_frac64(u64 x, u32 numer, u32 denom) { > u64 r1 = do_div(x, denom); > u64 r2 = r1 * numer; > > do_div(r2, denom); > return (x * numer) + r2; > } > > #endif > > ?
One more look to the users of MULDIV.
They all seems 32 bit for x. It means you don't need two do_div()s at all.
Just do something like:
u64 d = x * numer; do_div(d, denom); return d;
-- With Best Regards, Andy Shevchenko
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