From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f173.google.com (mail-io0-f173.google.com [209.85.223.173]) by kanga.kvack.org (Postfix) with ESMTP id 382F06B0253 for ; Fri, 31 Jul 2015 06:28:06 -0400 (EDT) Received: by ioii16 with SMTP id i16so80968978ioi.0 for ; Fri, 31 Jul 2015 03:28:06 -0700 (PDT) Received: from smtprelay.hostedemail.com (smtprelay0141.hostedemail.com. [216.40.44.141]) by mx.google.com with ESMTP id l9si2679336igx.102.2015.07.31.03.28.05 for ; Fri, 31 Jul 2015 03:28:05 -0700 (PDT) Message-ID: <1438338481.19675.72.camel@perches.com> Subject: Re: [PATCH 14/15] mm: Drop unlikely before IS_ERR(_OR_NULL) From: Joe Perches Date: Fri, 31 Jul 2015 03:28:01 -0700 In-Reply-To: <20150731093450.GA7505@linux> References: <91586af267deb26b905fba61a9f1f665a204a4e3.1438331416.git.viresh.kumar@linaro.org> <20150731085646.GA31544@node.dhcp.inet.fi> <20150731093450.GA7505@linux> Content-Type: text/plain; charset="ISO-8859-1" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Viresh Kumar Cc: yalin wang , "Kirill A. Shutemov" , Andrew Morton , linaro-kernel@lists.linaro.org, open list , "Aneesh Kumar K.V" , David Rientjes , Ebru Akagunduz , Johannes Weiner , "Kirill A. Shutemov" , "open list:MEMORY MANAGEMENT" , Mel Gorman , Michal Hocko , Vlastimil Babka On Fri, 2015-07-31 at 15:04 +0530, Viresh Kumar wrote: > On 31-07-15, 17:32, yalin wang wrote: > > > > > On Jul 31, 2015, at 16:56, Kirill A. Shutemov wrote: > > > > > > On Fri, Jul 31, 2015 at 02:08:34PM +0530, Viresh Kumar wrote: > > >> IS_ERR(_OR_NULL) already contain an 'unlikely' compiler flag and there > > >> is no need to do that again from its callers. Drop it. > > >> > > >> Signed-off-by: Viresh Kumar > > > > > > Acked-by: Kirill A. Shutemov > > > search in code, there are lots of using like this , does need add this check into checkpatch ? > > cc'd Joe for that. :) > > > # grep -r 'likely.*IS_ERR' . > > ./include/linux/blk-cgroup.h: if (unlikely(IS_ERR(blkg))) > > ./fs/nfs/objlayout/objio_osd.c: if (unlikely(IS_ERR(od))) { > > ./fs/cifs/readdir.c: if (unlikely(IS_ERR(dentry))) > > ./fs/ext4/extents.c: if (unlikely(IS_ERR(bh))) { > > ./fs/ext4/extents.c: if (unlikely(IS_ERR(path1))) { > > ./fs/ext4/extents.c: if (unlikely(IS_ERR(path2))) { > > Btw, my series has fixed all of them :) If it's all fixed, then it's unlikely to be needed in checkpatch. But given the unlikely was added when using gcc3.4, I wonder if it's still appropriate to use unlikely in IS_ERR at all. --- commit b5acea523151452c37cd428437e7576a291dd146 Author: Andrew Morton Date: Sun Aug 22 23:04:49 2004 -0700 [PATCH] mark IS_ERR as unlikely() It seems fair to assume that it is always unlikely that IS_ERR will return true. This patch changes the gcc-3.4-generated kernel text by ~500 bytes (less) so it's fair to assume that the compiler is indeed propagating unlikeliness out of inline functions. -- 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/ . Don't email: email@kvack.org