From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752215AbaEVAf5 (ORCPT ); Wed, 21 May 2014 20:35:57 -0400 Received: from mx9.pku.edu.cn ([162.105.129.172]:52009 "EHLO mail.pku.edu.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751260AbaEVAfz convert rfc822-to-8bit (ORCPT ); Wed, 21 May 2014 20:35:55 -0400 X-Greylist: delayed 544 seconds by postgrey-1.27 at vger.kernel.org; Wed, 21 May 2014 20:35:54 EDT X-Spam-Flag: NO X-Spam-Score: -307.483 Date: Thu, 22 May 2014 08:26:39 +0800 (CST) From: =?utf-8?B?566h6Zuq5rab?= To: Chen Gang Cc: gerrit@erg.abdn.ac.uk, Guan Xuetao , David Miller , dccp@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <1546102096.46113.1400718399706.JavaMail.root@bj-mail03.pku.edu.cn> In-Reply-To: <537BF116.9000900@gmail.com> Subject: =?utf-8?Q?=E5=9B=9E=E5=A4=8D=EF=BC=9A_[PATCH_linux-next]_?= =?utf-8?Q?net/dccp/timer.c:_use_'u?= =?utf-8?Q?64'_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: [162.105.129.134] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- Chen Gang 写道： > '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 > --- > net/dccp/timer.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/dccp/timer.c b/net/dccp/timer.c > index 16f0b22..1cd46a3 100644 > --- a/net/dccp/timer.c > +++ b/net/dccp/timer.c > @@ -280,7 +280,7 @@ static ktime_t dccp_timestamp_seed; > */ > u32 dccp_timestamp(void) > { > - s64 delta = ktime_us_delta(ktime_get_real(), dccp_timestamp_seed); > + u64 delta = (u64)ktime_us_delta(ktime_get_real(), dccp_timestamp_seed); Do you assume that delta should be very small? Otherwise, return value will be different if data type is changed. > > do_div(delta, 10); > return delta; > -- > 1.9.2.459.g68773ac