Re: [PATCH 3/4] scsi: fix compiler warning for sg

From: Sinan Kaya
Date: Thu Nov 05 2015 - 13:32:26 EST

On 11/5/2015 1:07 PM, Andy Shevchenko wrote:
OK, I didn't know that we had such a macro. To make this look like the other
>macro, I can do this.
>static inline u64 mult_frac64(u64 x, u32 numer, u32 denom)
> u64 quot;
> u64 rem = x % denom;
> u64 rem2;
> quot = x;
> do_div(quot, denom);
> rem2 = rem * numer;
> do_div(rem2, denom);
> return (quot * numer) + rem2;
Might be I did a wrong smaple, but do_div() returns two values actually.
You perhaps overlooked it and thus wrote something redundant above.

OK, I was looking at example usages in the kernel. The ones I looked always used the first argument as an input & output parameter. I got nervous about overwriting something.

void __ndelay(unsigned long long nsecs)
u64 end;

nsecs <<= 9;
do_div(nsecs, 125);

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);

I'll do a s/MULDIV/mult_frac64/g to address Timur's concern.

Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
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