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Date: Sun, 8 Nov 2015 20:17:39 -0500 From: Sinan Kaya <okaya@...eaurora.org> To: Andy Shevchenko <andy.shevchenko@...il.com> Cc: linux-scsi <linux-scsi@...r.kernel.org>, timur@...eaurora.org, cov@...eaurora.org, jcm@...hat.com, Doug Gilbert <dgilbert@...erlog.com>, "James E.J. Bottomley" <JBottomley@...n.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 3/4] scsi: fix compiler warning for sg On 11/5/2015 2:56 PM, Andy Shevchenko wrote: > On Thu, Nov 5, 2015 at 9:31 PM, Andy Shevchenko > <andy.shevchenko@...il.com> wrote: >> On Thu, Nov 5, 2015 at 8:32 PM, Sinan Kaya <okaya@...eaurora.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; >> } I'll use this instead. This is cleaner, scalable and functionally correct to the original code. I'll post a patch with this soon. >> >> #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; > -- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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