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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 6C8CDC3A5A8 for ; Wed, 4 Sep 2019 15:56:25 +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 41D6D22CED for ; Wed, 4 Sep 2019 15:56:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="IzwUMHCh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 41D6D22CED Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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=f5KwpNxCwbh2WA0MzpHb+XOvt/TI6JdpdcpVTcOlzPk=; b=IzwUMHChLlvnhv bAQlLoa2LGJ5bwp4gPvxQXZkLtFYGf8oDc+n0Kn/6MMLvfsVlQSLKZeOa6xI2uhR16efiK4f2Ww6v 7nApDtnrFY1Eix91Y0HcmVbGy6+GIc8LYxNdTDOrAAg7PD3sQGZO8QTi/pIBwHYMx7lqCQJKTWWg1 Dk7tX8/hRwQBHFr2Rr+8Sks9t5ldWEZapf7I8c7rAoe8QlvV6x7+bXQwavBW4fz8bWkf8VppZad2Q sI+AGvHxU7L7xnZEu3MQhCv036saKytRneABC+0UBRlRafeUZoXPI1OXN6cRN5y86a6d41N2t3+1T UoqI5gI6cwfIgniJ/FXQ==; 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 1i5Xdt-00010V-3b; Wed, 04 Sep 2019 15:56:21 +0000 Received: from mga02.intel.com ([134.134.136.20]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i5Xdq-000107-4S for linux-nvme@lists.infradead.org; Wed, 04 Sep 2019 15:56:19 +0000 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Sep 2019 08:56:16 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,467,1559545200"; d="scan'208";a="199059841" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by fmsmga001.fm.intel.com with ESMTP; 04 Sep 2019 08:56:16 -0700 Date: Wed, 4 Sep 2019 09:54:45 -0600 From: Keith Busch To: Christoph Hellwig Subject: Re: [PATCH] nvme-core: Fix subsystem instance mismatches Message-ID: <20190904155445.GD21302@localhost.localdomain> 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> <20190904154215.GA20422@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190904154215.GA20422@lst.de> User-Agent: Mutt/1.9.1 (2017-09-22) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190904_085618_219942_2E66CEA6 X-CRM114-Status: GOOD ( 17.61 ) 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 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 05:42:15PM +0200, Christoph Hellwig wrote: > 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. Can we just ensure there is never a matching controller then? This patch will accomplish that and simpler than wrapping the instance in a refcount'ed object: http://lists.infradead.org/pipermail/linux-nvme/2019-May/024142.html _______________________________________________ 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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 04BF5C3A5A8 for ; Wed, 4 Sep 2019 15:56:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE6F122CED for ; Wed, 4 Sep 2019 15:56:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567612580; bh=RMh5SN41NZE5u/rDTqAA4+0804mMUI9Vm26Q35MpjWA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=UhibJWT9zPkOyE9k5iFqAQjzHJ5zvxWbPAe+MwAqK+XUgLblc0BIWd4NqR9b1n3gB kcl/lEiRGn54/TAhMV1BliR2vJXRocH5WbRKwetvfXlEKQTFz8d6dPZvy+pYE8OrIN Kc9ozoYLSBahzg5y+xWVgDI+G4kdeecsBbtd0zrQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731506AbfIDP4T (ORCPT ); Wed, 4 Sep 2019 11:56:19 -0400 Received: from mga01.intel.com ([192.55.52.88]:10024 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727967AbfIDP4R (ORCPT ); Wed, 4 Sep 2019 11:56:17 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Sep 2019 08:56:16 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,467,1559545200"; d="scan'208";a="199059841" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by fmsmga001.fm.intel.com with ESMTP; 04 Sep 2019 08:56:16 -0700 Date: Wed, 4 Sep 2019 09:54:45 -0600 From: Keith Busch To: Christoph Hellwig Cc: 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: <20190904155445.GD21302@localhost.localdomain> 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> <20190904154215.GA20422@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190904154215.GA20422@lst.de> User-Agent: Mutt/1.9.1 (2017-09-22) 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 05:42:15PM +0200, Christoph Hellwig wrote: > 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. Can we just ensure there is never a matching controller then? This patch will accomplish that and simpler than wrapping the instance in a refcount'ed object: http://lists.infradead.org/pipermail/linux-nvme/2019-May/024142.html