From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9D7C6C432C0 for ; Thu, 21 Nov 2019 08:04:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4C28A20872 for ; Thu, 21 Nov 2019 08:04:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C28A20872 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AC2996B02E1; Thu, 21 Nov 2019 03:04:01 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A4B2F6B02E2; Thu, 21 Nov 2019 03:04:01 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 93A916B02E3; Thu, 21 Nov 2019 03:04:01 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0043.hostedemail.com [216.40.44.43]) by kanga.kvack.org (Postfix) with ESMTP id 793746B02E1 for ; Thu, 21 Nov 2019 03:04:01 -0500 (EST) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 2B4AA180AD80F for ; Thu, 21 Nov 2019 08:04:01 +0000 (UTC) X-FDA: 76179546282.11.water37_401e2bd37933d X-HE-Tag: water37_401e2bd37933d X-Filterd-Recvd-Size: 3291 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf26.hostedemail.com (Postfix) with ESMTP for ; Thu, 21 Nov 2019 08:04:00 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id C80DF68BFE; Thu, 21 Nov 2019 09:03:56 +0100 (CET) Date: Thu, 21 Nov 2019 09:03:56 +0100 From: Christoph Hellwig To: John Hubbard Cc: Andrew Morton , Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , Christoph Hellwig , Dan Williams , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jan Kara , Jason Gunthorpe , Jens Axboe , Jonathan Corbet , =?iso-8859-1?B?Suly9G1l?= Glisse , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman , Michal Hocko , Mike Kravetz , Paul Mackerras , Shuah Khan , Vlastimil Babka , bpf@vger.kernel.org, dri-devel@lists.freedesktop.org, kvm@vger.kernel.org, linux-block@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org, linux-rdma@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-mm@kvack.org, LKML , Christoph Hellwig , "Aneesh Kumar K . V" Subject: Re: [PATCH v7 02/24] mm/gup: factor out duplicate code from four routines Message-ID: <20191121080356.GA24784@lst.de> References: <20191121071354.456618-1-jhubbard@nvidia.com> <20191121071354.456618-3-jhubbard@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191121071354.456618-3-jhubbard@nvidia.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Nov 20, 2019 at 11:13:32PM -0800, John Hubbard wrote: > There are four locations in gup.c that have a fair amount of code > duplication. This means that changing one requires making the same > changes in four places, not to mention reading the same code four > times, and wondering if there are subtle differences. > > Factor out the common code into static functions, thus reducing the > overall line count and the code's complexity. > > Also, take the opportunity to slightly improve the efficiency of the > error cases, by doing a mass subtraction of the refcount, surrounded > by get_page()/put_page(). > > Also, further simplify (slightly), by waiting until the the successful > end of each routine, to increment *nr. Any reason for the spurious underscore in the function name? Otherwise this looks fine and might be a worthwhile cleanup to feed Andrew for 5.5 independent of the gut of the changes. Reviewed-by: Christoph Hellwig