From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161900AbbKEPLE (ORCPT ); Thu, 5 Nov 2015 10:11:04 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:47181 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1032907AbbKEPLA (ORCPT ); Thu, 5 Nov 2015 10:11:00 -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> 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: <563B7180.2000405@codeaurora.org> Date: Thu, 5 Nov 2015 10:10:56 -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 On 11/5/2015 3:48 AM, Andy Shevchenko wrote: > On Thu, Nov 5, 2015 at 6:46 AM, Sinan Kaya wrote: >> The MULDIV macro has been designed for small >> numbers. It emits an overflow warning on 64 bit >> systems. This patch places type casts in the >> parameters to fix the compiler warning. >> >> Signed-off-by: Sinan Kaya >> --- >> drivers/scsi/sg.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c >> index 9d7b7db..eb2739d 100644 >> --- a/drivers/scsi/sg.c >> +++ b/drivers/scsi/sg.c >> @@ -88,7 +88,10 @@ static void sg_proc_cleanup(void); >> * Of course an overflow is inavoidable if the result of muldiv doesn't fit >> * in 32 bits. >> */ >> -#define MULDIV(X,MUL,DIV) ((((X % DIV) * MUL) / DIV) + ((X / DIV) * MUL)) >> +static inline u64 MULDIV(u64 X, u32 MUL, u32 DIV) >> +{ >> + return ((((X % DIV) * MUL) / DIV) + ((X / DIV) * MUL)); >> +} > > Like kbuild bot already told you it would be nice to think of 32-bit > architectures. > > Moreover we have mult_frac() macro already for 32-bit numbers. > > For 64 bit numbers you need to do do_div(). > > Like: > > static inline u64 mult_frac64(u64 x, u32 m, u32 n) > { > u64 ret; > > ret = do_div(x, n); > return ret * m; > } > 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; } #define MULDIV(X,MUL,DIV) mult_frac64(X, MUL, DIV) > >> >> #define SG_DEFAULT_TIMEOUT MULDIV(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ) >> >> -- >> 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-scsi" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- 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