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=-5.3 required=3.0 tests=BAYES_00, 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 61811C4363D for ; Wed, 23 Sep 2020 14:49:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DE68421D43 for ; Wed, 23 Sep 2020 14:49:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DE68421D43 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 511276B0070; Wed, 23 Sep 2020 10:49:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 49A056B0073; Wed, 23 Sep 2020 10:49:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 392BB6B0070; Wed, 23 Sep 2020 10:49:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0053.hostedemail.com [216.40.44.53]) by kanga.kvack.org (Postfix) with ESMTP id 0F56B6B0070 for ; Wed, 23 Sep 2020 10:49:49 -0400 (EDT) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id AD485185B85D7 for ; Wed, 23 Sep 2020 14:49:48 +0000 (UTC) X-FDA: 77294610456.12.straw51_240552227157 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin12.hostedemail.com (Postfix) with ESMTP id 979D5180363E8; Wed, 23 Sep 2020 14:32:59 +0000 (UTC) X-HE-Tag: straw51_240552227157 X-Filterd-Recvd-Size: 3038 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf04.hostedemail.com (Postfix) with ESMTP; Wed, 23 Sep 2020 14:32:54 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 0E0AE6736F; Wed, 23 Sep 2020 16:32:52 +0200 (CEST) Date: Wed, 23 Sep 2020 16:32:51 +0200 From: Christoph Hellwig To: Al Viro Cc: Christoph Hellwig , Andrew Morton , Jens Axboe , Arnd Bergmann , David Howells , David Laight , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH 5/9] fs: remove various compat readv/writev helpers Message-ID: <20200923143251.GA14062@lst.de> References: <20200923060547.16903-1-hch@lst.de> <20200923060547.16903-6-hch@lst.de> <20200923142549.GK3421308@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200923142549.GK3421308@ZenIV.linux.org.uk> 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, Sep 23, 2020 at 03:25:49PM +0100, Al Viro wrote: > On Wed, Sep 23, 2020 at 08:05:43AM +0200, Christoph Hellwig wrote: > > COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd, > > - const struct compat_iovec __user *,vec, > > + const struct iovec __user *, vec, > > Um... Will it even compile? > > > #ifdef __ARCH_WANT_COMPAT_SYS_PREADV64 > > COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd, > > - const struct compat_iovec __user *,vec, > > + const struct iovec __user *, vec, > > Ditto. Look into include/linux/compat.h and you'll see > > asmlinkage long compat_sys_preadv64(unsigned long fd, > const struct compat_iovec __user *vec, > unsigned long vlen, loff_t pos); > > How does that manage to avoid the compiler screaming bloody > murder? That's a very good question. But it does not just compile but actually works. Probably because all the syscall wrappers mean that we don't actually generate the normal names. I just tried this: --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -468,7 +468,7 @@ asmlinkage long sys_lseek(unsigned int fd, off_t offset, asmlinkage long sys_read(unsigned int fd, char __user *buf, size_t count); asmlinkage long sys_write(unsigned int fd, const char __user *buf, size_t count); -asmlinkage long sys_readv(unsigned long fd, +asmlinkage long sys_readv(void *fd, for fun, and the compiler doesn't care either..