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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 C528CC11F66 for ; Wed, 14 Jul 2021 18:09:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95F1261042 for ; Wed, 14 Jul 2021 18:09:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239861AbhGNSMQ (ORCPT ); Wed, 14 Jul 2021 14:12:16 -0400 Received: from mail-pg1-f179.google.com ([209.85.215.179]:39757 "EHLO mail-pg1-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229651AbhGNSMP (ORCPT ); Wed, 14 Jul 2021 14:12:15 -0400 Received: by mail-pg1-f179.google.com with SMTP id a2so3319630pgi.6; Wed, 14 Jul 2021 11:09:23 -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:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=LIzD3a4Y0Ejr+434x3kFvkLLT9Fc2hxKYkwrbGXVjSY=; b=enqIO1V/DfyIEJFQR86o+piWXwL4Ut323CcN7t9BSZkB4QtHUPQipbrILyqSCZbPO6 fkE3apmIc7rzYSEwglk6hhdtsaYUEqNWaxYZ+rNBRn71oViLc+ZSz5Uj4T4rxhHhb0uK tzb3/tK2XoXMaDfdSJXJrgr1uFfcwYNI8uemM8mWn9VOPxuR8Oe2uHQ0E5H/alirItnL qiB40yr/EHlkLgb9YRmnqENXS7hBHEel79UMpTbnoxCtmP+JIHa0D26dCS1kMc01RuBB Ar9Zosq0eYNYfE7fOUIz9Tf1NmuFZyvcnUpaUUF/G6M+K9u3Mki58FdkhpXcX2lZdKM5 Ossg== X-Gm-Message-State: AOAM5322m2GsCN0EgVvYe+NXGa81o5D9mQkymxBNNmGc1hsEKl3ltDLp Ja/NKctCvKALJ73AAGHkUMk= X-Google-Smtp-Source: ABdhPJx9teTmAtYN19Yd/nQG8C6ZbdsPelnS5mxH8YBC7VR+v8bydqlC8BZSICOe/VSBsiH69KOoAw== X-Received: by 2002:a63:e26:: with SMTP id d38mr5923790pgl.42.1626286163206; Wed, 14 Jul 2021 11:09:23 -0700 (PDT) Received: from ?IPv6:2620:0:1000:2004:91cc:a7b9:6739:15bc? ([2620:0:1000:2004:91cc:a7b9:6739:15bc]) by smtp.gmail.com with ESMTPSA id q17sm2787438pjd.42.2021.07.14.11.09.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 Jul 2021 11:09:22 -0700 (PDT) Subject: Re: [PATCH] scsi: ufs: add missing host_lock in setup_xfer_req To: Bean Huo , Jaegeuk Kim , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Cc: Stanley Chu , Can Guo , Bean Huo , Asutosh Das References: <20210701005117.3846179-1-jaegeuk@kernel.org> <38432018-e8bf-f9f3-00bf-cd4b81c95c88@acm.org> <69b367bc44084f901d0d71fb8f9633ea7e5df36b.camel@gmail.com> From: Bart Van Assche Message-ID: Date: Wed, 14 Jul 2021 11:09:20 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <69b367bc44084f901d0d71fb8f9633ea7e5df36b.camel@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/13/21 12:45 PM, Bean Huo wrote: > This change only impacts on the Samsung exynos platform. and Can's > optimization patch is to optimise the host_lock,, and removed > host_lock, now add back in this function makes sense to me. > but I am thinking how about hba->host_sem? Hi Bean, Calls of exynos_ufs_specify_nexus_t_xfer_req() must be serialized, hence Jaegeuks' patch. This function is called from the I/O submission path so performance matters. My understanding is that spinlocks have less overhead than semaphores. Hence the choice for a spinlock. Thanks, Bart.