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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 2AB11C433E0 for ; Thu, 21 May 2020 09:11:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08DE42070A for ; Thu, 21 May 2020 09:11:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728635AbgEUJL6 (ORCPT ); Thu, 21 May 2020 05:11:58 -0400 Received: from verein.lst.de ([213.95.11.211]:53831 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728545AbgEUJL6 (ORCPT ); Thu, 21 May 2020 05:11:58 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id DBA5368C4E; Thu, 21 May 2020 11:11:50 +0200 (CEST) Date: Thu, 21 May 2020 11:11:50 +0200 From: 'Christoph Hellwig' To: David Laight Cc: 'Christoph Hellwig' , "David S. Miller" , Jakub Kicinski , Eric Dumazet , Alexey Kuznetsov , Hideaki YOSHIFUJI , Vlad Yasevich , Neil Horman , Marcelo Ricardo Leitner , Jon Maloy , Ying Xue , "drbd-dev@lists.linbit.com" , "linux-kernel@vger.kernel.org" , "linux-rdma@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "target-devel@vger.kernel.org" , "linux-afs@lists.infradead.org" , "linux-cifs@vger.kernel.org" , "cluster-devel@redhat.com" , "ocfs2-devel@oss.oracle.com" , "netdev@vger.kernel.org" , "linux-sctp@vger.kernel.org" , "ceph-devel@vger.kernel.org" , "rds-devel@oss.oracle.com" , "linux-nfs@vger.kernel.org" Subject: Re: remove kernel_setsockopt and kernel_getsockopt v2 Message-ID: <20200521091150.GA8401@lst.de> References: <20200520195509.2215098-1-hch@lst.de> <138a17dfff244c089b95f129e4ea2f66@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <138a17dfff244c089b95f129e4ea2f66@AcuMS.aculab.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Thu, May 21, 2020 at 08:01:33AM +0000, David Laight wrote: > How much does this increase the kernel code by? 44 files changed, 660 insertions(+), 843 deletions(-) > You are also replicating a lot of code making it more > difficult to maintain. No, I specifically don't. > I don't think the performance of an socket option code > really matters - it is usually done once when a socket > is initialised and the other costs of establishing a > connection will dominate. > > Pulling the user copies outside the [gs]etsocksopt switch > statement not only reduces the code size (source and object) > and trivially allows kernel_[sg]sockopt() to me added to > the list of socket calls. > > It probably isn't possible to pull the usercopies right > out into the syscall wrapper because of some broken > requests. Please read through the previous discussion of the rationale and the options. We've been there before. > I worried about whether getsockopt() should read the entire > user buffer first. SCTP needs the some of it often (including a > sockaddr_storage in one case), TCP needs it once. > However the cost of reading a few words is small, and a big > buffer probably needs setting to avoid leaking kernel > memory if the structure has holes or fields that don't get set. > Reading from userspace solves both issues. As mention in the thread on the last series: That was my first idea, but we have way to many sockopts, especially in obscure protocols that just hard code the size. The chance of breaking userspace in a way that can't be fixed without going back to passing user pointers to get/setsockopt is way to high to commit to such a change unfortunately.