From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?utf-8?B?566h6Zuq5rab?= Date: Thu, 22 May 2014 23:58:11 +0000 Subject: =?utf-8?Q?=E5=9B=9E=E5=A4=8D=EF=BC=9A_Re:_[PATCH_linux-nex?= =?utf-8?Q?t]_net/dccp/timer.c:_use_?= Message-Id: <263613432.57393.1400803091663.JavaMail.root@bj-mail03.pku.edu.cn> List-Id: References: <579164883.46799.1400720806850.JavaMail.root@bj-mail03.pku.edu.cn> In-Reply-To: <579164883.46799.1400720806850.JavaMail.root@bj-mail03.pku.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: dccp@vger.kernel.org ----- David Miller 写道： > From: Chen Gang > Date: Wed, 21 May 2014 08:19:34 +0800 > > > 'dccp_timestamp_seed' is initialized once by ktime_get_real() in > > dccp_timestamping_init(). It is always less than ktime_get_real() > > in dccp_timestamp(). > > > > Then, ktime_us_delta() in dccp_timestamp() will always return positive > > number. So can use manual type cast to let compiler and do_div() know > > about it to avoid warning. > > > > The related warning (with allmodconfig under unicore32): > > > > CC [M] net/dccp/timer.o > > net/dccp/timer.c: In function ‘dccp_timestamp’: > > net/dccp/timer.c:285: warning: comparison of distinct pointer types lacks a cast > > > > > > Signed-off-by: Chen Gang > > Applied to net-next, thanks. > > But that type check in include/asm-generic/div64.h is bogus, it should > be checking sizeof(X) = 8 rather than the type thing, it just wants to > make sure that the value is 64-bit regardless of it's signedness. > > The arch local implementations do not do this, and that's why very few > other people notice this warning. Arch-dependent codes implement it with unsigned long long type. And, every warning should not be ignored. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752644AbaEVX6b (ORCPT ); Thu, 22 May 2014 19:58:31 -0400 Received: from mx10.pku.edu.cn ([162.105.129.173]:39024 "EHLO mail.pku.edu.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751247AbaEVX63 convert rfc822-to-8bit (ORCPT ); Thu, 22 May 2014 19:58:29 -0400 X-Spam-Flag: NO X-Spam-Score: -307.489 Date: Fri, 23 May 2014 07:58:11 +0800 (CST) From: =?utf-8?B?566h6Zuq5rab?= To: David Miller Cc: gang chen 5i5j , gerrit@erg.abdn.ac.uk, gxt@mprc.pku.edu.cn, dccp@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <263613432.57393.1400803091663.JavaMail.root@bj-mail03.pku.edu.cn> In-Reply-To: <20140522.153313.958087444510569794.davem@davemloft.net> Subject: =?utf-8?Q?=E5=9B=9E=E5=A4=8D=EF=BC=9A_Re:_[PATCH_linux-nex?= =?utf-8?Q?t]_net/dccp/timer.c:_use_?= =?utf-8?Q?'u64'_instead_of_'s64'_to_avoid_compiler's_warning?= MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Originating-IP: [162.105.129.97] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- David Miller 写道： > From: Chen Gang > Date: Wed, 21 May 2014 08:19:34 +0800 > > > 'dccp_timestamp_seed' is initialized once by ktime_get_real() in > > dccp_timestamping_init(). It is always less than ktime_get_real() > > in dccp_timestamp(). > > > > Then, ktime_us_delta() in dccp_timestamp() will always return positive > > number. So can use manual type cast to let compiler and do_div() know > > about it to avoid warning. > > > > The related warning (with allmodconfig under unicore32): > > > > CC [M] net/dccp/timer.o > > net/dccp/timer.c: In function ‘dccp_timestamp’: > > net/dccp/timer.c:285: warning: comparison of distinct pointer types lacks a cast > > > > > > Signed-off-by: Chen Gang > > Applied to net-next, thanks. > > But that type check in include/asm-generic/div64.h is bogus, it should > be checking sizeof(X) == 8 rather than the type thing, it just wants to > make sure that the value is 64-bit regardless of it's signedness. > > The arch local implementations do not do this, and that's why very few > other people notice this warning. Arch-dependent codes implement it with unsigned long long type. And, every warning should not be ignored.