Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752280AbbKIBRr (ORCPT ); Sun, 8 Nov 2015 20:17:47 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:33467 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751968AbbKIBRp (ORCPT ); Sun, 8 Nov 2015 20:17:45 -0500 Subject: Re: [PATCH 3/4] scsi: fix compiler warning for sg To: Andy Shevchenko References: <1446698789-19308-1-git-send-email-okaya@codeaurora.org> <1446698789-19308-3-git-send-email-okaya@codeaurora.org> <563B7180.2000405@codeaurora.org> <563BA0B3.6080506@codeaurora.org> Cc: linux-scsi , timur@codeaurora.org, cov@codeaurora.org, jcm@redhat.com, Doug Gilbert , "James E.J. Bottomley" , "linux-kernel@vger.kernel.org" From: Sinan Kaya Message-ID: <563FF433.8000308@codeaurora.org> Date: Sun, 8 Nov 2015 20:17:39 -0500 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1950 Lines: 72 On 11/5/2015 2:56 PM, Andy Shevchenko wrote: > On Thu, Nov 5, 2015 at 9:31 PM, Andy Shevchenko > wrote: >> On Thu, Nov 5, 2015 at 8:32 PM, Sinan Kaya 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/