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,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 38756C3F2D1 for ; Wed, 4 Mar 2020 19:02:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0671F2166E for ; Wed, 4 Mar 2020 19:02:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729702AbgCDTC0 (ORCPT ); Wed, 4 Mar 2020 14:02:26 -0500 Received: from relay5-d.mail.gandi.net ([217.70.183.197]:57355 "EHLO relay5-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729600AbgCDTC0 (ORCPT ); Wed, 4 Mar 2020 14:02:26 -0500 X-Originating-IP: 92.243.9.8 Received: from localhost (joshtriplett.org [92.243.9.8]) (Authenticated sender: josh@joshtriplett.org) by relay5-d.mail.gandi.net (Postfix) with ESMTPSA id F31211C0009; Wed, 4 Mar 2020 19:02:23 +0000 (UTC) Date: Wed, 4 Mar 2020 11:02:23 -0800 From: Josh Triplett To: Jens Axboe Cc: io-uring@vger.kernel.org, jlayton@kernel.org Subject: Re: [PATCH 6/6] io_uring: allow specific fd for IORING_OP_ACCEPT Message-ID: <20200304190223.GA16251@localhost> References: <20200304180016.28212-1-axboe@kernel.dk> <20200304180016.28212-7-axboe@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200304180016.28212-7-axboe@kernel.dk> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Wed, Mar 04, 2020 at 11:00:16AM -0700, Jens Axboe wrote: > sqe->len can be set to a specific fd we want to use for accept4(), so > it uses that one instead of just assigning a free unused one. [...] > + accept->open_fd = READ_ONCE(sqe->len); > + if (!accept->open_fd) > + accept->open_fd = -1; 0 is a valid file descriptor. I realize that it seems unlikely, but I went to a fair bit of trouble in my patch series to ensure that userspace could use any valid file descriptor openat2, without a corner case like "you can't open as file descriptor 0", even though it would have been more convenient to just say "if you pass a non-zero fd in open_how". Please consider accepting a flag to determine the validity of open_fd. - Josh Triplett