From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id 772D18D0040 for ; Thu, 31 Mar 2011 15:52:35 -0400 (EDT) Received: by ewy9 with SMTP id 9so1115640ewy.14 for ; Thu, 31 Mar 2011 12:52:29 -0700 (PDT) Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes Subject: Re: [PATCH 05/12] mm: alloc_contig_range() added References: <1301577368-16095-1-git-send-email-m.szyprowski@samsung.com> <1301577368-16095-6-git-send-email-m.szyprowski@samsung.com> <1301587361.31087.1040.camel@nimitz> <20110331192821.GF14441@home.goodmis.org> Date: Thu, 31 Mar 2011 21:52:26 +0200 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: "Michal Nazarewicz" Message-ID: In-Reply-To: <20110331192821.GF14441@home.goodmis.org> Sender: owner-linux-mm@kvack.org List-ID: To: Steven Rostedt Cc: Marek Szyprowski , Dave Hansen , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, linux-mm@kvack.org, Kyungmin Park , Andrew Morton , KAMEZAWA Hiroyuki , Ankita Garg , Daniel Walker , Johan MOSSBERG , Mel Gorman , Pawel Osciak On Thu, 31 Mar 2011 21:28:21 +0200, Steven Rostedt wrote: > WARN_ON() should never do anything but test. That ret++ does not belong > inside the WARN_ON() condition. If there are other locations in the > kernel that do that, then those locations need to be fixed. Testing implies evaluating, so if we allow: if (++i == end) { /* ... */ } I see no reason why not to allow: if (WARN_ON(++i == end)) { /* ... */ } In both cases the condition is tested. >> On Thu, 2011-03-31 at 15:16 +0200, Marek Szyprowski wrote: >>> + ret = 0; >>> + while (!PageBuddy(pfn_to_page(start & (~0UL << ret)))) >>> + if (WARN_ON(++ret >= MAX_ORDER)) >>> + return -EINVAL; > On Thu, Mar 31, 2011 at 09:02:41AM -0700, Dave Hansen wrote: >> In any case, please pull the ++ret bit out of the WARN_ON(). Some >> people like to do: >> >> #define WARN_ON(...) do{}while(0) >> >> to save space on some systems. On Thu, 31 Mar 2011 21:26:50 +0200, Steven Rostedt wrote: > That should be fixed, as the if (WARN_ON()) has become a standard in > most of the kernel. Removing WARN_ON() should be: > > #define WARN_ON(x) ({0;}) This would break a lot of code which expect that testing to take place. Also see . > But I agree, that there should be no "side effects" inside a WARN_ON(), > which that "++ret" is definitely one. Thus I don't really agree with this point. At any rate, I don't really care. -- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michal "mina86" Nazarewicz (o o) ooo +----------ooO--(_)--Ooo-- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org