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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, 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 254F7C433E1 for ; Tue, 14 Jul 2020 03:41:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A7B720890 for ; Tue, 14 Jul 2020 03:41:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726766AbgGNDlx (ORCPT ); Mon, 13 Jul 2020 23:41:53 -0400 Received: from mail-pj1-f67.google.com ([209.85.216.67]:36905 "EHLO mail-pj1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726768AbgGNDlx (ORCPT ); Mon, 13 Jul 2020 23:41:53 -0400 Received: by mail-pj1-f67.google.com with SMTP id o22so884210pjw.2; Mon, 13 Jul 2020 20:41:52 -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=FIkoYpJoY156GHlaAk/Z9PrJ8CxCxosbs70run2YrjM=; b=nJS6RLlihVTrdRIr5nFAJUTDBXqio16yilTPkLc2Bp8bqTekx0ob9iuRmkl2zMVnIi 2WKIKcATTG9QsPdrS7ZXCUWzPjllfl4su7gR0jBuLztx8LraBw6N283/Dta9VnfdfpFB hP3sbe4C/Jo75jvVEQ3ErECwj2Mmxe0wuQX69L8cHKsY6i4tQltOjQNipa+Pghyhg7B4 myNDjtrxsPx03cskVhG4A5TyDYtEeWfiHEFddxv8mhgh2mzbflFN9nv48Hd1QAD71km5 63gLSzgQAnpXODZj71I/5kCyyIwOVB9nzstL55vlWnhUAd3FzhHfI7hUL8xL8Zi8kRLV sJGA== X-Gm-Message-State: AOAM532oCwdHYrXi7uvvl5Lxik30Qch6eyoON3oEBWGAdA75nM5E/ycd Tf66kg6u96xDw4FFYYkoCi/o3IK4 X-Google-Smtp-Source: ABdhPJzV0zDlFgGwGnecA8mDKdz1bBhuAchtA+8ZGU5FLtvGqIRgsog41df9pB3T3jZp/n6J7DC7Wg== X-Received: by 2002:a17:90a:d3d7:: with SMTP id d23mr2479430pjw.232.1594698111736; Mon, 13 Jul 2020 20:41:51 -0700 (PDT) Received: from [192.168.50.147] (c-73-241-217-19.hsd1.ca.comcast.net. [73.241.217.19]) by smtp.gmail.com with ESMTPSA id x3sm15749338pfn.154.2020.07.13.20.41.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Jul 2020 20:41:50 -0700 (PDT) Subject: Re: [PATCH v2 2/4] scsi: ufs: Fix imbalanced scsi_block_reqs_cnt caused by ufshcd_hold() To: Can Guo , asutoshd@codeaurora.org, nguyenb@codeaurora.org, hongwus@codeaurora.org, rnayak@codeaurora.org, linux-scsi@vger.kernel.org, kernel-team@android.com, saravanak@google.com, salyzyn@google.com Cc: Alim Akhtar , Avri Altman , "James E.J. Bottomley" , "Martin K. Petersen" , Stanley Chu , Bean Huo , open list References: <1594693693-22466-1-git-send-email-cang@codeaurora.org> <1594693693-22466-3-git-send-email-cang@codeaurora.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: <5470be4c-cfa4-ebe5-a817-e53f26c7eaf6@acm.org> Date: Mon, 13 Jul 2020 20:41:49 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <1594693693-22466-3-git-send-email-cang@codeaurora.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 2020-07-13 19:28, Can Guo wrote: > The scsi_block_reqs_cnt increased in ufshcd_hold() is supposed to be > decreased back in ufshcd_ungate_work() in a paired way. However, if > specific ufshcd_hold/release sequences are met, it is possible that > scsi_block_reqs_cnt is increased twice but only one ungate work is > queued. To make sure scsi_block_reqs_cnt is handled by ufshcd_hold() and > ufshcd_ungate_work() in a paired way, increase it only if queue_work() > returns true. > > Signed-off-by: Can Guo > --- > drivers/scsi/ufs/ufshcd.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > index ebf7a95..33214bb 100644 > --- a/drivers/scsi/ufs/ufshcd.c > +++ b/drivers/scsi/ufs/ufshcd.c > @@ -1611,12 +1611,12 @@ int ufshcd_hold(struct ufs_hba *hba, bool async) > */ > /* fallthrough */ > case CLKS_OFF: > - ufshcd_scsi_block_requests(hba); > hba->clk_gating.state = REQ_CLKS_ON; > trace_ufshcd_clk_gating(dev_name(hba->dev), > hba->clk_gating.state); > - queue_work(hba->clk_gating.clk_gating_workq, > - &hba->clk_gating.ungate_work); > + if (queue_work(hba->clk_gating.clk_gating_workq, > + &hba->clk_gating.ungate_work)) > + ufshcd_scsi_block_requests(hba); > /* > * fall through to check if we should wait for this > * work to be done or not. Since "ungate_work" involves calling ufshcd_scsi_unblock_requests() and since this patch changes the order in which ufshcd_scsi_block_requests() and queue_work() are called, I think this patch introduces a race condition. Has it been considered to leave the ufshcd_scsi_block_requests() call where it is and to call ufshcd_scsi_unblock_requests() if queue_work() fails? Thanks, Bart.