Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755213AbaDVJwt (ORCPT ); Tue, 22 Apr 2014 05:52:49 -0400 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 Message-ID: <53563BE4.6070703@gmail.com> Date: Tue, 22 Apr 2014 17:52:36 +0800 From: Chen Gang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Pavel Machek CC: "Rafael J. Wysocki" , Guan Xuetao , len.brown@intel.com, "linux-kernel@vger.kernel.org" , "linux-pm@vger.kernel.org" Subject: Re: [PATCH v2] kernel/power/hibernate.c: use 'u64' instead of 's64' to avoid warning References: <5355C5F0.6020606@gmail.com> <20140422072112.GB14108@amd.pavel.ucw.cz> <535620C7.2080700@gmail.com> In-Reply-To: <535620C7.2080700@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@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 sure >>> of 'start' is not bigger than 'stop', or it will report warning. >>> >>> Even if 'start' was really bigger than 'stop', it would print incorrect >>> 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 ‘swsusp_show_speed’: >>> kernel/power/hibernate.c:237: warning: comparison of distinct pointer types lacks a cast >>> >>> >> >> Certainly better, but >> >>> - s64 elapsed_centisecs64; >>> + u64 elapsed_centisecs64; >>> int centisecs; >>> int k; >>> int kps; >>> >>> elapsed_centisecs64 = 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 = 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 >> > > Hmm... that sounds reasonable to me. If no any other reply within 2 > days, I shall send patch v3 for it. > > BTW: sorry, I guess I can not finish allmodconfig for unicore32 within > this month (2014-04-30) -- at present I only finish 40-50%, I > will/should try to finish it within next month. > > > Thanks. > -- Chen Gang Open, share, and attitude like air, water, and life which God blessed -- 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/