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=-7.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,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 16B2BC433F5 for ; Tue, 7 Sep 2021 15:32:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE97D60F14 for ; Tue, 7 Sep 2021 15:32:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345284AbhIGPda (ORCPT ); Tue, 7 Sep 2021 11:33:30 -0400 Received: from out30-45.freemail.mail.aliyun.com ([115.124.30.45]:50999 "EHLO out30-45.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344935AbhIGPda (ORCPT ); Tue, 7 Sep 2021 11:33:30 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=haoxu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0Unc-CFO_1631028741; Received: from 30.30.107.109(mailfrom:haoxu@linux.alibaba.com fp:SMTPD_---0Unc-CFO_1631028741) by smtp.aliyun-inc.com(127.0.0.1); Tue, 07 Sep 2021 23:32:22 +0800 Subject: Re: [PATCH] io_uring: check file_slot early when accept use fix_file mode To: Jens Axboe Cc: io-uring@vger.kernel.org, Pavel Begunkov , Joseph Qi References: <20210907151653.18501-1-haoxu@linux.alibaba.com> <3ca81c51-87fb-2f1d-f3f7-92abafdd5cca@kernel.dk> From: Hao Xu Message-ID: <1cff2f6f-d979-f667-180f-b09d548aa640@linux.alibaba.com> Date: Tue, 7 Sep 2021 23:32:21 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <3ca81c51-87fb-2f1d-f3f7-92abafdd5cca@kernel.dk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org 在 2021/9/7 下午11:24, Jens Axboe 写道: > On 9/7/21 9:16 AM, Hao Xu wrote: >> check file_slot early in io_accept_prep() to avoid wasted effort in >> failure cases. > > It's generally better to just let the failure cases deal with it instead > of having checks in multiple places. This is a failure path, so we don't > care about making it fail early. Optimizations should be for the hot path, > which is not a malformed sqe. I have a question here: if we do do_accept() and but fail in io_install_fixed_file(), do we lose the conn_fd return by do_accept() forever? >