From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Sinan Kaya <okaya@codeaurora.org>
Cc: linux-scsi <linux-scsi@vger.kernel.org>,
timur@codeaurora.org, cov@codeaurora.org, jcm@redhat.com,
Doug Gilbert <dgilbert@interlog.com>,
"James E.J. Bottomley" <JBottomley@odin.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/4] scsi: fix compiler warning for sg
Date: Thu, 5 Nov 2015 21:56:42 +0200 [thread overview]
Message-ID: <CAHp75VdaeGZ-cD6j4cUc_wdGnGYN2_x6vqua3Xrt2Fi8MGH+tQ@mail.gmail.com> (raw)
In-Reply-To: <CAHp75Vfx0eCtP4H9kMPxy4g6UQM5jnBjJ43xnenn+h3N6uyvag@mail.gmail.com>
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
next prev parent reply other threads:[~2015-11-05 19:56 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-05 4:46 [PATCH 1/4] scsi: mpt2sas: try 64 bit DMA when 32 bit DMA fails Sinan Kaya
2015-11-05 4:46 ` [PATCH 2/4] scsi: mpt3sas: " Sinan Kaya
2015-11-05 4:46 ` [PATCH 3/4] scsi: fix compiler warning for sg Sinan Kaya
2015-11-05 5:39 ` kbuild test robot
2015-11-05 6:40 ` kbuild test robot
2015-11-05 6:51 ` kbuild test robot
2015-11-05 8:48 ` Andy Shevchenko
2015-11-05 15:10 ` Sinan Kaya
2015-11-05 15:25 ` Timur Tabi
2015-11-05 18:07 ` Andy Shevchenko
2015-11-05 18:32 ` Sinan Kaya
2015-11-05 19:31 ` Andy Shevchenko
2015-11-05 19:56 ` Andy Shevchenko [this message]
2015-11-05 20:16 ` Sinan Kaya
2015-11-09 1:17 ` Sinan Kaya
2015-11-05 4:46 ` [PATCH 4/4] scsi: mptxsas: offload IRQ execution Sinan Kaya
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