Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754525AbaDUUJf (ORCPT ); Mon, 21 Apr 2014 16:09:35 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:38398 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750891AbaDUUJc (ORCPT ); Mon, 21 Apr 2014 16:09:32 -0400 Date: Mon, 21 Apr 2014 22:09:30 +0200 From: Pavel Machek To: Chen Gang Cc: Guan Xuetao , "Rafael J. Wysocki" , len.brown@intel.com, "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] kernel/power/hibernate.c: be sure of 'start' is not bigger than 'stop' Message-ID: <20140421200930.GA9880@amd.pavel.ucw.cz> References: <53551FCB.3030109@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <53551FCB.3030109@gmail.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 2014-04-21 21:40:27, 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. > > 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 > > Signed-off-by: Chen Gang > { > - s64 elapsed_centisecs64; > + u64 elapsed_centisecs64; > int centisecs; > int k; > int kps; > > elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start); > + if ((s64)elapsed_centisecs64 < 0) { > + printk(KERN_ERR "PM: stop: %llu < start %llu\n", > + timeval_to_ns(stop), timeval_to_ns(start)); > + return; > + } > do_div(elapsed_centisecs64, NSEC_PER_SEC / 100); > centisecs = elapsed_centisecs64; > if (centisecs == 0) Quite a lot of code to shut up warning in mostly debugging function... is there alternative method of shutting it up? Have you seen < 0 values in wild? Is it worth handing that situation? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/