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=-2.3 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 60E24CA9EA0 for ; Tue, 22 Oct 2019 22:10:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 30B6C2084B for ; Tue, 22 Oct 2019 22:10:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730611AbfJVWKa (ORCPT ); Tue, 22 Oct 2019 18:10:30 -0400 Received: from mail-pg1-f193.google.com ([209.85.215.193]:45721 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725837AbfJVWKa (ORCPT ); Tue, 22 Oct 2019 18:10:30 -0400 Received: by mail-pg1-f193.google.com with SMTP id r1so10777921pgj.12 for ; Tue, 22 Oct 2019 15:10:30 -0700 (PDT) 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=TsCb0C4kNPbn2k1q/tpNwv38VXAcvW2m1kuwWMRf0mI=; b=DBwaj3w0oFf2dc+mgXDkGCjeIKbct3juTF87lG4PW4vfztH19uWWd9WMv2s7b+vB04 Aep4nte1GxDSLNZv5i5rcdu3T+hTQtkONfuYvhZ4lpiC22qnTH0G8t2bWMLityggzwce 8Ewmk0yMs2LINkTgoieOelzNxYIESDrGAj67kCTjrssZ9G1mtGAEdw/wZqj9pBZzge5A 6WTiw0UuPASmESsMyJe6QF3bMy7dcYNaiMI28LjtvH6jnOZsnOtRQJmpWHcwfmKZMP+3 F93CrXom4to4FWoZLp4X/KK/g5LMt0fdwLLHpmO5sD+i/e3yLQJ3NEUSc0pmUbBNtU7D Fkrw== X-Gm-Message-State: APjAAAU3aY6cuKyqQ8mkkVa+RbRGwAdfd6MnHSSzY7YSmwMeTIoXoL4z eOJbVawZtYinAUPMh9exHdhOcHZS X-Google-Smtp-Source: APXvYqyETvHDFnGkaPpkkDQcJbVMjapOeievNlGTHpo70QHGfULUV5P/ScblbQqG7TErw2FJeXYh+g== X-Received: by 2002:a63:e211:: with SMTP id q17mr5648714pgh.316.1571782229069; Tue, 22 Oct 2019 15:10:29 -0700 (PDT) Received: from localhost.localdomain ([2601:647:4000:c3:ccbd:2d81:281:ddbd]) by smtp.gmail.com with ESMTPSA id f6sm20866662pfq.169.2019.10.22.15.10.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 22 Oct 2019 15:10:27 -0700 (PDT) Subject: Re: [PATCH] srp_daemon: Use maximum initiator to target IU size To: Honggang LI Cc: linux-rdma@vger.kernel.org References: <20191018044104.21353-1-honli@redhat.com> <1d811fc0-1f74-b546-b296-a4e9f8c33d86@acm.org> <20191018152253.GA32562@dhcp-128-227.nay.redhat.com> <21142610-1e01-4ce8-635c-2fe677e69cf9@acm.org> <20191022070025.GA20278@dhcp-128-227.nay.redhat.com> From: Bart Van Assche Autocrypt: addr=bvanassche@acm.org; prefer-encrypt=mutual; keydata= mQENBFSOu4oBCADcRWxVUvkkvRmmwTwIjIJvZOu6wNm+dz5AF4z0FHW2KNZL3oheO3P8UZWr LQOrCfRcK8e/sIs2Y2D3Lg/SL7qqbMehGEYcJptu6mKkywBfoYbtBkVoJ/jQsi2H0vBiiCOy fmxMHIPcYxaJdXxrOG2UO4B60Y/BzE6OrPDT44w4cZA9DH5xialliWU447Bts8TJNa3lZKS1 AvW1ZklbvJfAJJAwzDih35LxU2fcWbmhPa7EO2DCv/LM1B10GBB/oQB5kvlq4aA2PSIWkqz4 3SI5kCPSsygD6wKnbRsvNn2mIACva6VHdm62A7xel5dJRfpQjXj2snd1F/YNoNc66UUTABEB AAG0JEJhcnQgVmFuIEFzc2NoZSA8YnZhbmFzc2NoZUBhY20ub3JnPokBOQQTAQIAIwUCVI67 igIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEHFcPTXFzhAJ8QkH/1AdXblKL65M Y1Zk1bYKnkAb4a98LxCPm/pJBilvci6boefwlBDZ2NZuuYWYgyrehMB5H+q+Kq4P0IBbTqTa jTPAANn62A6jwJ0FnCn6YaM9TZQjM1F7LoDX3v+oAkaoXuq0dQ4hnxQNu792bi6QyVdZUvKc macVFVgfK9n04mL7RzjO3f+X4midKt/s+G+IPr4DGlrq+WH27eDbpUR3aYRk8EgbgGKvQFdD CEBFJi+5ZKOArmJVBSk21RHDpqyz6Vit3rjep7c1SN8s7NhVi9cjkKmMDM7KYhXkWc10lKx2 RTkFI30rkDm4U+JpdAd2+tP3tjGf9AyGGinpzE2XY1K5AQ0EVI67igEIAKiSyd0nECrgz+H5 PcFDGYQpGDMTl8MOPCKw/F3diXPuj2eql4xSbAdbUCJzk2ETif5s3twT2ER8cUTEVOaCEUY3 eOiaFgQ+nGLx4BXqqGewikPJCe+UBjFnH1m2/IFn4T9jPZkV8xlkKmDUqMK5EV9n3eQLkn5g lco+FepTtmbkSCCjd91EfThVbNYpVQ5ZjdBCXN66CKyJDMJ85HVr5rmXG/nqriTh6cv1l1Js T7AFvvPjUPknS6d+BETMhTkbGzoyS+sywEsQAgA+BMCxBH4LvUmHYhpS+W6CiZ3ZMxjO8Hgc ++w1mLeRUvda3i4/U8wDT3SWuHcB3DWlcppECLkAEQEAAYkBHwQYAQIACQUCVI67igIbDAAK CRBxXD01xc4QCZ4dB/0QrnEasxjM0PGeXK5hcZMT9Eo998alUfn5XU0RQDYdwp6/kMEXMdmT oH0F0xB3SQ8WVSXA9rrc4EBvZruWQ+5/zjVrhhfUAx12CzL4oQ9Ro2k45daYaonKTANYG22y //x8dLe2Fv1By4SKGhmzwH87uXxbTJAUxiWIi1np0z3/RDnoVyfmfbbL1DY7zf2hYXLLzsJR mSsED/1nlJ9Oq5fALdNEPgDyPUerqHxcmIub+pF0AzJoYHK5punqpqfGmqPbjxrJLPJfHVKy goMj5DlBMoYqEgpbwdUYkH6QdizJJCur4icy8GUNbisFYABeoJ91pnD4IGei3MTdvINSZI5e Message-ID: <5f664232-ca58-c25c-e9b1-e441c053c818@acm.org> Date: Tue, 22 Oct 2019 15:10:26 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <20191022070025.GA20278@dhcp-128-227.nay.redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On 2019-10-22 00:00, Honggang LI wrote: > +static bool use_imm_data(void) > +{ > +#ifdef __linux__ > + bool ret = false; > + char flag = 0; > + int cnt; > + int fd = open("/sys/module/ib_srp/parameters/use_imm_data", O_RDONLY); > + > + if (fd < 0) > + return false; > + cnt = read(fd, &flag, 1); > + if (cnt != 1) > + return false; > + > + if (!strncmp(&flag, "Y", 1)) > + ret = true; > + close(fd); > + return ret; > +#else > + return false; > +#endif > +} There is already plenty of Linux-specific code in srp_daemon. The #ifdef __linux__ / #endif guard does not seem useful to me. There is a file descriptor leak in the above function, namely if read() returns another value than 1. The use_imm_data kernel module parameter was introduced in kernel v5.0 (commit 882981f4a411; "RDMA/srp: Add support for immediate data"). The max_it_iu_size will be introduced in kernel v5.5 (commit 547ed331bbe8; "RDMA/srp: Add parse function for maximum initiator to target IU size"). So the above check will help for kernel versions before v5.0 but not for kernel versions [v5.0..v5.5). If that is really what you want, please explain this in a comment above the use_imm_data() function. Thanks, Bart.