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=-2.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 EF9F7C3A5A7 for ; Wed, 4 Sep 2019 15:42:25 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C689522CEA for ; Wed, 4 Sep 2019 15:42:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="DQADnB7T" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C689522CEA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=SfIKF+kgsgE95GyiLiEfGgpsZDO52fVkR9+2cZv5mvA=; b=DQADnB7TECfSVS eIeTnBPrrJ9KkhUhBxZwAfCrapcvO3Od6a+oZEYzgReoza9DxJWUoYSRyAGknjlnp0vPQnmLnQpmC jzJO2R95fCCrF/c2/UaZuQZmwrvWMlut4dEK3p++/5xP0RPqoflv8oqlf3bj2enzBxPR6JKMj6UGR uf8USM/VzooQfb9lyVp7dWMhKhm/VsR92aGSFRc6cDx8fZADqJzRPzXpEXK1d/WPWNcIpRfpIM/Nm wERIYZSScXVTx8/dDuobs4lQ+NTZOd9phDLs1IUYb3DZaYJnC7VlSyl5f6pcM0+EY6wX+FRBB0+ns /edx1pR3orjPv8QczZWQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i5XQM-0004Ub-Dr; Wed, 04 Sep 2019 15:42:22 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i5XQK-0004U5-C3 for linux-nvme@lists.infradead.org; Wed, 04 Sep 2019 15:42:21 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 08E65227A8A; Wed, 4 Sep 2019 17:42:16 +0200 (CEST) Date: Wed, 4 Sep 2019 17:42:15 +0200 From: Christoph Hellwig To: Keith Busch Subject: Re: [PATCH] nvme-core: Fix subsystem instance mismatches Message-ID: <20190904154215.GA20422@lst.de> References: <20190831000139.7662-1-logang@deltatee.com> <20190831152910.GA29439@localhost.localdomain> <33af4d94-9f6d-9baa-01fa-0f75ccee263e@deltatee.com> <20190903164620.GA20847@localhost.localdomain> <20190904060558.GA10849@lst.de> <20190904144426.GB21302@localhost.localdomain> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190904144426.GB21302@localhost.localdomain> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190904_084220_562982_D1F773DB X-CRM114-Status: GOOD ( 11.61 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Keith Busch , Hannes Reinecke , Sagi Grimberg , "Martin K . Petersen" , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Jens Axboe , Logan Gunthorpe , Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Sep 04, 2019 at 08:44:27AM -0600, Keith Busch wrote: > Let me step through an example: > > Ctrl A gets instance 0. > > Its subsystem gets the same instance, and takes ref count on it: > all namespaces in this subsystem will use '0'. > > Ctrl B gets instance 1, and it's in the same subsystem as Ctrl A so > no new subsytem is allocated. > > Ctrl A is disconnected, dropping its ref on instance 0, but the > subsystem still has its refcount, making it unavailable. > > Ctrl A is reconnected, and allocates instance 2 because 0 is still in > use. > > Now all the namespaces in this subsystem are prefixed with nvme0, but no > controller exists with the same prefix. We still have inevitable naming > mismatch, right? I think th major confusion was that we can use the same handle for and unrelated subsystem vs controller, and that would avoid it. I don't see how we can avoid the controller is entirely different from namespace problem ever. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme 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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 516CAC3A5A7 for ; Wed, 4 Sep 2019 15:42:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 30C1722CF7 for ; Wed, 4 Sep 2019 15:42:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731406AbfIDPmU (ORCPT ); Wed, 4 Sep 2019 11:42:20 -0400 Received: from verein.lst.de ([213.95.11.211]:40375 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727967AbfIDPmT (ORCPT ); Wed, 4 Sep 2019 11:42:19 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 08E65227A8A; Wed, 4 Sep 2019 17:42:16 +0200 (CEST) Date: Wed, 4 Sep 2019 17:42:15 +0200 From: Christoph Hellwig To: Keith Busch Cc: Christoph Hellwig , Jens Axboe , Hannes Reinecke , Sagi Grimberg , "Martin K . Petersen" , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Keith Busch , Logan Gunthorpe Subject: Re: [PATCH] nvme-core: Fix subsystem instance mismatches Message-ID: <20190904154215.GA20422@lst.de> References: <20190831000139.7662-1-logang@deltatee.com> <20190831152910.GA29439@localhost.localdomain> <33af4d94-9f6d-9baa-01fa-0f75ccee263e@deltatee.com> <20190903164620.GA20847@localhost.localdomain> <20190904060558.GA10849@lst.de> <20190904144426.GB21302@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190904144426.GB21302@localhost.localdomain> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 04, 2019 at 08:44:27AM -0600, Keith Busch wrote: > Let me step through an example: > > Ctrl A gets instance 0. > > Its subsystem gets the same instance, and takes ref count on it: > all namespaces in this subsystem will use '0'. > > Ctrl B gets instance 1, and it's in the same subsystem as Ctrl A so > no new subsytem is allocated. > > Ctrl A is disconnected, dropping its ref on instance 0, but the > subsystem still has its refcount, making it unavailable. > > Ctrl A is reconnected, and allocates instance 2 because 0 is still in > use. > > Now all the namespaces in this subsystem are prefixed with nvme0, but no > controller exists with the same prefix. We still have inevitable naming > mismatch, right? I think th major confusion was that we can use the same handle for and unrelated subsystem vs controller, and that would avoid it. I don't see how we can avoid the controller is entirely different from namespace problem ever.