Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759316Ab1CaTwd (ORCPT ); Thu, 31 Mar 2011 15:52:33 -0400 Received: from mail-ew0-f46.google.com ([209.85.215.46]:44400 "EHLO mail-ew0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759054Ab1CaTwa (ORCPT ); Thu, 31 Mar 2011 15:52:30 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:content-type:to:cc:subject:references:date:mime-version :content-transfer-encoding:from:organization:message-id:in-reply-to :user-agent; b=FZI4eBVCeakGvICxRHFhzkrDDFv7xbA6IRCOE+xydkHaSFo/N1vf+VUJghW/6b11X6 VMgqfZjcMYbAuLK+3ogGMt6W7XZnNhhD0btTbNyIwvpRz335ghIOB4sZFcjGCNwYh6rM jErnYj8z+5L/xkp0g4gsxkkIeJP8B6Y8aIgj4= Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes 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" 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" Organization: Google Message-ID: In-Reply-To: <20110331192821.GF14441@home.goodmis.org> User-Agent: Opera Mail/11.01 (Linux) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2000 Lines: 55 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 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/