From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chen Gang Subject: Re: [PATCH v2] kernel/power/hibernate.c: use 'u64' instead of 's64' to avoid warning Date: Tue, 22 Apr 2014 17:52:36 +0800 Message-ID: <53563BE4.6070703@gmail.com> References: <5355C5F0.6020606@gmail.com> <20140422072112.GB14108@amd.pavel.ucw.cz> <535620C7.2080700@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-pd0-f171.google.com ([209.85.192.171]:50354 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753779AbaDVJwn (ORCPT ); Tue, 22 Apr 2014 05:52:43 -0400 In-Reply-To: <535620C7.2080700@gmail.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Pavel Machek Cc: "Rafael J. Wysocki" , Guan Xuetao , len.brown@intel.com, "linux-kernel@vger.kernel.org" , "linux-pm@vger.kernel.org" On 04/22/2014 03:56 PM, Chen Gang wrote: > On 04/22/2014 03:21 PM, Pavel Machek wrote: >> On Tue 2014-04-22 09:29:20, Chen Gang wrote: >>> For do_div(), it need 'u64' type, which means the outside must be s= ure >>> of 'start' is not bigger than 'stop', or it will report warning. >>> >>> Even if 'start' was really bigger than 'stop', it would print incor= rect >>> information, but for kernel, it still can continue, so use WARN_ON(= ) is >>> enough. >>> >>> The related warning (with allmodconfig for unicore32): >>> >>> CC kernel/power/hibernate.o >>> kernel/power/hibernate.c: In function =E2=80=98swsusp_show_speed=E2= =80=99: >>> kernel/power/hibernate.c:237: warning: comparison of distinct poi= nter types lacks a cast >>> >>> >> >> Certainly better, but >> >>> - s64 elapsed_centisecs64; >>> + u64 elapsed_centisecs64; >>> int centisecs; >>> int k; >>> int kps; >>> =20 >>> elapsed_centisecs64 =3D timeval_to_ns(stop) - timeval_to_ns(start= ); >>> + WARN_ON((s64)elapsed_centisecs64 < 0); How about to use one line comments instead of WARN_ON()? /* * If "(s64)elapsed_centisecs64 < 0", it will print long elapsed * time, it is obvious enough to user for what went wrong. */ >>> do_div(elapsed_centisecs64, NSEC_PER_SEC / 100); >>> centisecs =3D elapsed_centisecs64; >> >> ...do we need to do the WARN_ON()? Only result of underflow will be >> very long elapsed time reported... that does not sound too >> bad. ... and it will be quite obvious what went wrong. >> Pavel >> >=20 > Hmm... that sounds reasonable to me. If no any other reply within 2 > days, I shall send patch v3 for it. >=20 > BTW: sorry, I guess I can not finish allmodconfig for unicore32 withi= n > this month (2014-04-30) -- at present I only finish 40-50%, I > will/should try to finish it within next month. >=20 >=20 > Thanks. >=20 --=20 Chen Gang Open, share, and attitude like air, water, and life which God blessed