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 C7AECC4363D for ; Wed, 23 Sep 2020 14:32:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8329021D43 for ; Wed, 23 Sep 2020 14:32:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726603AbgIWOc5 (ORCPT ); Wed, 23 Sep 2020 10:32:57 -0400 Received: from verein.lst.de ([213.95.11.211]:48690 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726587AbgIWOc4 (ORCPT ); Wed, 23 Sep 2020 10:32:56 -0400 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) Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org 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..