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 51808C38A2D for ; Mon, 24 Oct 2022 15:02:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231874AbiJXPCM (ORCPT ); Mon, 24 Oct 2022 11:02:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231655AbiJXPBx (ORCPT ); Mon, 24 Oct 2022 11:01:53 -0400 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4EDF41366A4 for ; Mon, 24 Oct 2022 06:38:48 -0700 (PDT) Received: by mail-pf1-x431.google.com with SMTP id g62so4956467pfb.10 for ; Mon, 24 Oct 2022 06:38:48 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=6vie4dh+louXoUQMxLwJz2RE5N7M8k6YAevG4uZHlAM=; b=ZeklBEM++ZyiB9531bxr/Scj9q9MWVpJsuyTPhMoekTv+rbo5Vyvc70nqbVFwwN3M/ Uwk1qBUFWdyVDZu179Y2T66TNiOWC1+Q47wDFrHBYchJXHANXEftyXtqlE9bGWeUoNlm SFGcQ/rUvH9Zbt/iWyA8ui399qtsDFU5bOKb6UlOJ4njJZZDmxG218rWnfQp5HdXDw+T HpS9UbjbVIIncMtoJPw5hB6O2kgM+XwmYlMfzQG2jc+vBD/trbB1XR4Wjgo/QK9OQ+lK iRmVpvkJM1cZBTXpS3NCv1LC3kClFnH1ME9R3pKS8udDJ1zo7csnVVDE2N+PVkpAi95b +4Rg== X-Gm-Message-State: ACrzQf3gaZGyFD52UHh/QQgRv9jQs0RGHAW5ttbAJ745S0ak2+0nCEN0 YR/XuvpsK3uNAWn9/29fdOg= X-Google-Smtp-Source: AMsMyM6ckg/oHhCgaWHmli0CaXhP/8VL4mNEVYUHYL8F3rk1ClcrEraBR6UfQF3YnlCK0f+GKELy9w== X-Received: by 2002:a05:6a00:2303:b0:56b:cd7e:6cb with SMTP id h3-20020a056a00230300b0056bcd7e06cbmr5528386pfh.77.1666618524742; Mon, 24 Oct 2022 06:35:24 -0700 (PDT) Received: from [192.168.3.219] ([98.51.102.78]) by smtp.gmail.com with ESMTPSA id cx10-20020a17090afd8a00b002132adb61ccsm432730pjb.48.2022.10.24.06.35.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Oct 2022 06:35:23 -0700 (PDT) Message-ID: <77784776-4e58-47d9-abde-a782f5ca7d3a@acm.org> Date: Mon, 24 Oct 2022 06:35:21 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.3 Subject: Re: [PATCH 5/8] blk-mq: add tagset quiesce interface Content-Language: en-US To: Chao Leng , Christoph Hellwig , Jens Axboe , Keith Busch , Sagi Grimberg Cc: Ming Lei , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org References: <20221020105608.1581940-1-hch@lst.de> <20221020105608.1581940-6-hch@lst.de> <01e45c37-5db8-b1a5-33c6-251da2637fb5@acm.org> From: Bart Van Assche In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 10/23/22 18:57, Chao Leng wrote: > blk_mq_quiesce_tagset() support concurrency. blk_mq_quiesce_tagset() just > check the flag(QUEUE_FLAG_SKIP_TAGSET_QUIESCE), it has no impact on > concurrency. Hi Chao, I think it depends on how the QUEUE_FLAG_SKIP_TAGSET_QUIESCE flag is set. I agree if that flag is set once and never modified that there is no race. What I'm wondering about is whether there could be a need for block drivers to set the QUEUE_FLAG_SKIP_TAGSET_QUIESCE flag just before blk_mq_quiesce_tagset() is called and cleared immediately after blk_mq_quiesce_tagset() returns? In that case I think there is a race condition. Thanks, Bart.