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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3943AC433EF for ; Fri, 25 Mar 2022 09:07:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350483AbiCYJIe (ORCPT ); Fri, 25 Mar 2022 05:08:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40468 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229940AbiCYJId (ORCPT ); Fri, 25 Mar 2022 05:08:33 -0400 Received: from mail-ed1-x52d.google.com (mail-ed1-x52d.google.com [IPv6:2a00:1450:4864:20::52d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5310CD33A; Fri, 25 Mar 2022 02:06:59 -0700 (PDT) Received: by mail-ed1-x52d.google.com with SMTP id k10so8485236edj.2; Fri, 25 Mar 2022 02:06:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=VhdVUAWHXjzUGq4oP9g7su55g+qs75mizf7QQXpvJEw=; b=euZVYebCE4XJ6h2KVEIZN/sxeNdWBhCLQ41F3VbBi73AFa8s6umon5UZl9YlT8u9vD fp5poY35XXFvreG/fDo9a+X3woO+AKZa38cO0DSYqK+Dg+LmytrvB9q4rUXqVhP0E0qK bWQTPeb835PslboqVCKK8yVwr6+RZXn+Pcj5irL12oEbLAKjT/cPXQAmCp4Uz1Wu1Kjg +tffZ3ZZLqEIRodZ7+iJuewi0Age1X4soOIbsnvEAit3U5iUNsTTEoz4k4QfSfCdqEHh yH+VoYrCj3wY1l5+lrFZJAzocKld8uAYeFiOVipvXPyK+TigtwMG/UQDqaT08hNZyR6C HZIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=VhdVUAWHXjzUGq4oP9g7su55g+qs75mizf7QQXpvJEw=; b=es+MrmEUR4sGbkxC2OWDgyCL+qq+RKcAA4YuZVLgT4RISul2PO3ataL5PF849JifjP JEeRWdlxw5mIUH1/dvURJn+eSc96T5XDY4/nEzP6w48NvB1WMBXaiqu6wRSuZ1+vqemS g5sbd5QnhydkSOVIci/5sJB50sJuspeICtbmOTHEHNorNOZ7p7hlIFh+b/iUVSb95kiP J9Wsu1tFAMRgHG8o1iI+pAzWwvHR0l0elY8D8F2SXxCBvRTWet+k+dzVm1WWOuQUYhQb EaKTxqcqTvlPVKstERTCVs1F9tNTCUQiCiYEQOYQowwcu79rrmXxYv5ED+2uHy6ffKrW sRQg== X-Gm-Message-State: AOAM532NasESIedtkyxqnHrWKwzRKMrEJJzVgkFGnjhufBjUGfJj6s4c eT/xbNSEs3DM4hK3UEpmk98= X-Google-Smtp-Source: ABdhPJx01pPWcYHPsWa/D2UX3hyEAgDAM3v69gqG2zc9S5TZfdLa41DCwYMxLs2+YR31sY0zcWOsoQ== X-Received: by 2002:a05:6402:4315:b0:419:2e38:ab8f with SMTP id m21-20020a056402431500b004192e38ab8fmr11628871edc.250.1648199218448; Fri, 25 Mar 2022 02:06:58 -0700 (PDT) Received: from [192.168.178.40] (ipbcc1cfad.dynamic.kabel-deutschland.de. [188.193.207.173]) by smtp.gmail.com with ESMTPSA id e9-20020a170906c00900b006d4a45869basm2087116ejz.199.2022.03.25.02.06.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Mar 2022 02:06:58 -0700 (PDT) Message-ID: Date: Fri, 25 Mar 2022 10:06:57 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [RFC 3/3] scsi: target: tcmu: Support zero copy Content-Language: en-US To: Xiaoguang Wang , linux-mm@kvack.org, target-devel@vger.kernel.org, linux-scsi@vger.kernel.org Cc: linux-block@vger.kernel.org, xuyu@linux.alibaba.com References: <20220318095531.15479-1-xiaoguang.wang@linux.alibaba.com> <20220318095531.15479-4-xiaoguang.wang@linux.alibaba.com> <94b00e49-5efb-658f-3142-42e7cc551d19@gmail.com> <57da7e54-f582-3b10-52a9-5166adacf4e6@linux.alibaba.com> From: Bodo Stroesser In-Reply-To: <57da7e54-f582-3b10-52a9-5166adacf4e6@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: target-devel@vger.kernel.org On 23.03.22 15:33, Xiaoguang Wang wrote: ... snip ... >> What happens if the tcmu device currently is not open / mapped? > I'm not sure how it will happen. > But we may check whether udev->vma has a valid value. If yes, > it'll enter tcmu_cmd_zerocopy_map(). > Yeah, but what I also wanted to suggest is, that if userspace maps the uio device while zero copy cmds already being in the ring, you have to iterate over those cmds and populate the mapping. Bodo