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[23.128.96.18]) by mx.google.com with ESMTP id l23si10953388ejq.537.2021.03.15.05.07.47; Mon, 15 Mar 2021 05:08:12 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@veeam.com header.s=mx4 header.b=gFh+ULS+; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=veeam.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230330AbhCOMGY (ORCPT + 99 others); Mon, 15 Mar 2021 08:06:24 -0400 Received: from mx4.veeam.com ([104.41.138.86]:50584 "EHLO mx4.veeam.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230169AbhCOMGX (ORCPT ); Mon, 15 Mar 2021 08:06:23 -0400 Received: from mail.veeam.com (prgmbx01.amust.local [172.24.0.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx4.veeam.com (Postfix) with ESMTPS id 32402171E; Mon, 15 Mar 2021 15:06:18 +0300 (MSK) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=veeam.com; s=mx4; t=1615809978; bh=mVn36BTSzFhaZLEUHYffL8xe3v6UOYz/YXSHVjys07s=; h=Date:From:To:CC:Subject:References:In-Reply-To:From; b=gFh+ULS+jNH0u4XnkuWd8sf+8rvbY99vFfRjjm4mDEf6PHHBD3hbXQdcJTXrWousR kvi9VzOitKCEQcZacJvCpfiUJC65HMpxP2Rqln8k33a+IdaAGwD5jnjfs0Yajxl/87 VqqUvn6sP+9xGhzKK9yp89S4zV2dW0RQ71xl/o6o= Received: from veeam.com (172.24.14.5) by prgmbx01.amust.local (172.24.0.171) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.721.2; Mon, 15 Mar 2021 13:06:16 +0100 Date: Mon, 15 Mar 2021 15:06:08 +0300 From: Sergei Shtepa To: Christoph Hellwig CC: Mike Snitzer , Alasdair Kergon , Hannes Reinecke , Jens Axboe , "dm-devel@redhat.com" , "linux-block@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-api@vger.kernel.org" , Pavel Tide Subject: Re: [PATCH v7 1/3] block: add blk_mq_is_queue_frozen() Message-ID: <20210315120608.GA30489@veeam.com> References: <1615563895-28565-1-git-send-email-sergei.shtepa@veeam.com> <1615563895-28565-2-git-send-email-sergei.shtepa@veeam.com> <20210312190641.GA2550@redhat.com> <20210314091441.GA3773360@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: <20210314091441.GA3773360@infradead.org> X-Originating-IP: [172.24.14.5] X-ClientProxiedBy: prgmbx01.amust.local (172.24.0.171) To prgmbx01.amust.local (172.24.0.171) X-EsetResult: clean, is OK X-EsetId: 37303A29D2A50B58627C62 X-Veeam-MMEX: True Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The 03/14/2021 12:14, Christoph Hellwig wrote: > On Fri, Mar 12, 2021 at 02:06:41PM -0500, Mike Snitzer wrote: > > This is returning a frozen state that is immediately stale. I don't > > think any code calling this is providing the guarantees you think it > > does due to the racey nature of this state once the mutex is dropped. > > The code only uses it for asserts in the form of WARN_ONs. But perhaps it is possible to come up with a more elegant solution? I'll think about it. -- Sergei Shtepa Veeam Software developer.