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 5FC22C3F2C6 for ; Tue, 3 Mar 2020 05:57:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B969215A4 for ; Tue, 3 Mar 2020 05:57:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725897AbgCCF5W (ORCPT ); Tue, 3 Mar 2020 00:57:22 -0500 Received: from mail-pj1-f67.google.com ([209.85.216.67]:52095 "EHLO mail-pj1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725845AbgCCF5W (ORCPT ); Tue, 3 Mar 2020 00:57:22 -0500 Received: by mail-pj1-f67.google.com with SMTP id l8so858112pjy.1; Mon, 02 Mar 2020 21:57:21 -0800 (PST) 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=yo+dRABTent3gLV01eNpbbUuwD5LriWTxo0eVCxvitI=; b=bYdYb+fOmZungJVGXjhM9Igk6TLCVJm1RKob39vvvMvpnBmTsT8aZXAJ7COGJxGHfC WMInzof4uBn1wVSZTSgtfUI9NL3ksfCliSviz+etQ4FU1aml8aoTdacKCQmTHSyXPRJg 6YHRQWbhALPEUdnPqnT1Bwz3je+4JjHSJCqiVrSS5hnwYnP/0u9MbNK1KHbLFGYYhjPZ BqNTVywRDyonErL5KVR4koZv40PB7GSFWOkmRA2nB9kNExECeNUAqg9ej00kFVO66v4p 3FADuT/HQx/6HcJz/9VLcTmS6vWZtPUa5E/zx+TjAIifen/eoQra/AR/4TgAWzVYJrot KRBw== X-Gm-Message-State: ANhLgQ1vZFskPosf1cwiUtlTFr3X4uw0pnSnPQev0BqfkXrdJ4IUb7Bh tXPoH/IzDnp/kjocL/d4yTc= X-Google-Smtp-Source: ADFU+vuLo+fbJdzafAO81GBOO8Np+dvuSM0iWkucvcFxJeUnfaS5noqjbikr/TtXpSYc5OnHV4txYQ== X-Received: by 2002:a17:90a:230d:: with SMTP id f13mr2307642pje.128.1583215041029; Mon, 02 Mar 2020 21:57:21 -0800 (PST) Received: from ?IPv6:2601:647:4000:d7:5909:8e52:fd69:e98d? ([2601:647:4000:d7:5909:8e52:fd69:e98d]) by smtp.gmail.com with ESMTPSA id b15sm22930323pft.58.2020.03.02.21.57.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Mar 2020 21:57:19 -0800 (PST) Subject: Re: [PATCH v9 20/25] block/rnbd: server: main functionality To: Danil Kipnis Cc: Jack Wang , linux-block@vger.kernel.org, linux-rdma@vger.kernel.org, Jens Axboe , Christoph Hellwig , Sagi Grimberg , Leon Romanovsky , Doug Ledford , Jason Gunthorpe , Jack Wang , rpenyaev@suse.de, pankaj.gupta@cloud.ionos.com References: <20200221104721.350-1-jinpuwang@gmail.com> <20200221104721.350-21-jinpuwang@gmail.com> <33864f54-62af-cb5f-45fa-55a283dcd434@acm.org> 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: Date: Mon, 2 Mar 2020 21:57:17 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2020-03-02 01:58, Danil Kipnis wrote: > On Sun, Mar 1, 2020 at 3:58 AM Bart Van Assche wrote: >> >> On 2020-02-21 02:47, Jack Wang wrote: >>> +static int dev_search_path_set(const char *val, const struct kernel_param *kp) >>> +{ >>> + char *dup; >>> + >>> + if (strlen(val) >= sizeof(dev_search_path)) >>> + return -EINVAL; >>> + >>> + dup = kstrdup(val, GFP_KERNEL); >>> + >>> + if (dup[strlen(dup) - 1] == '\n') >>> + dup[strlen(dup) - 1] = '\0'; >>> + >>> + strlcpy(dev_search_path, dup, sizeof(dev_search_path)); >>> + >>> + kfree(dup); >>> + pr_info("dev_search_path changed to '%s'\n", dev_search_path); >>> + >>> + return 0; >>> +} >> >> It is not necessary in this function to do memory allocation. Something >> like the following (untested) code should be sufficient: >> >> const char *p = strrchr(val, '\n') ? : val + strlen(val); >> >> snprintf(dev_search_path, sizeof(dev_search_path), "%.*s", >> (int)(p - val), val); >> >> How are concurrent attempts to change dev_search_path serialized? >> > Hi Bart, > > thanks a lot for your comments. Will try to avoid the allocation. The > module parameter is readonly. It's only set during module init - I > guess we don't need to handle concurrent access? Right, if this function is only called during module init there is no need to worry about concurrency. Bart.