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=-8.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 2BD40C47258 for ; Mon, 4 May 2020 15:53:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08FFF20705 for ; Mon, 4 May 2020 15:53:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JrfRQ8/P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729527AbgEDPx2 (ORCPT ); Mon, 4 May 2020 11:53:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1729479AbgEDPxY (ORCPT ); Mon, 4 May 2020 11:53:24 -0400 Received: from mail-wr1-x442.google.com (mail-wr1-x442.google.com [IPv6:2a00:1450:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6BA69C061A0E; Mon, 4 May 2020 08:53:24 -0700 (PDT) Received: by mail-wr1-x442.google.com with SMTP id s8so11268752wrt.9; Mon, 04 May 2020 08:53:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:autocrypt:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=a51OfRZ33jZudrw71sJOVnYwq5K9qTUEcP4pBHMr04A=; b=JrfRQ8/P7x/T5NAffxXkepwKmvwZK3c+IHiTDqRUz4I+CNaR9rIsAzheuLUPeKecdq 18Eu9YPwKO2809csIUMr18/QT/Mn8nZAJD0u5pjdAZkHJozr0R1EjeFLBnhf837aCOU6 L59+dtAztMayqeD6CD/REdfp9qG7Vlb4Tbx0SOGtM+oyfXGQ/Rv9Yd6useR0gIbDKhJ9 xIZwAfxSDfoX8qYL9/jzm1zHQ0FWYT7N1mLUQT+BsVJPrWviGg6xTuQ7ilmKvPOF/Njj fxhZsgH1JINnmYdmLeSPiGer6dXPYo7PvFpjYRShDwEd6eJuskfc8bQ7lZOPTbUB3jIo OwcQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=a51OfRZ33jZudrw71sJOVnYwq5K9qTUEcP4pBHMr04A=; b=KJ7E4uyXaXbRK20JcoldnPi9KkLzQ2NaMIgrK40HmBVV7wiiwFTcSyA3VT7RjCoypP fW4DPdIdyfJ+J0KdVMcU6XcuJ6DA4tiPwOYeh0oMB7rhSTqhbzGKsw5guS1O3sPbHNpm leDyx+wehElP2GtoZC4o4t5VEHjrkbY2cMlI8W/cBI7qOjF2a5ZjM4ggnLLTrWsa+B/B /MQsK0WinWKimJQRAkH3JcVxs6YWoN0MgSvvuXnBsosYB0J2YQMg+25t+bEts6xGWop+ l6Qvq5RXnTwXWrZrII0VtjacKqWwxqPEokEl4RV21j+JIvinvTemalyGOCjKKG46no2g OA7g== X-Gm-Message-State: AGi0PuYFZ+MUOMd00KlPmlv/xt49XraUT+vfTUDPJqoLJVK94ibJL/As ETOaUv5PFTdmjF9p6d3Mg6jxNFEC X-Google-Smtp-Source: APiQypLktSGrl9Czf2iXPJCpsgaisVYVHpeQnFjMU3AhYBvXXlyz7dbfXsF3KL0dP0oidqNycuHqrw== X-Received: by 2002:a5d:6742:: with SMTP id l2mr12713590wrw.138.1588607602913; Mon, 04 May 2020 08:53:22 -0700 (PDT) Received: from [192.168.43.158] ([109.126.133.135]) by smtp.gmail.com with ESMTPSA id k14sm19424026wrp.53.2020.05.04.08.53.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 May 2020 08:53:22 -0700 (PDT) Subject: Re: [PATCH][next] io_uring: Remove logically dead code in io_splice To: Jens Axboe , "Gustavo A. R. Silva" , Alexander Viro Cc: io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <20200504151912.GA22779@embeddedor> From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Message-ID: <55bf573d-52f9-9131-ff08-49231a88abce@gmail.com> Date: Mon, 4 May 2020 18:52:17 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/05/2020 18:25, Jens Axboe wrote: > On 5/4/20 9:19 AM, Gustavo A. R. Silva wrote: >> In case force_nonblock happens to be true, the function returns >> at: >> >> 2779 if (force_nonblock) >> 2780 return -EAGAIN; >> >> before reaching this line of code. So, the null check on force_nonblock >> at 2785, is never actually being executed. >> >> Addresses-Coverity-ID: 1492838 ("Logically dead code") >> Fixes: 2fb3e82284fc ("io_uring: punt splice async because of inode mutex") >> Signed-off-by: Gustavo A. R. Silva >> --- >> fs/io_uring.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index e5dfbbd2aa34..4b1efb062f7f 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -2782,7 +2782,7 @@ static int io_splice(struct io_kiocb *req, bool force_nonblock) >> poff_in = (sp->off_in == -1) ? NULL : &sp->off_in; >> poff_out = (sp->off_out == -1) ? NULL : &sp->off_out; >> ret = do_splice(in, poff_in, out, poff_out, sp->len, flags); >> - if (force_nonblock && ret == -EAGAIN) >> + if (ret == -EAGAIN) >> return -EAGAIN; > > This isn't right, it should just remove the two lines completely. But > also see: Oh, right, it will ignore O_NONBLOCK and be resubmitted, as going through io_wq_submit_work(). I need to be more attentive. > > https://lore.kernel.org/io-uring/529ea928-88a6-2cbe-ba8c-72b4c68cc7e8@kernel.dk/T/#u > -- Pavel Begunkov