From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758976Ab2EVPAo (ORCPT ); Tue, 22 May 2012 11:00:44 -0400 Received: from mx2.netapp.com ([216.240.18.37]:26397 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753968Ab2EVPAm (ORCPT ); Tue, 22 May 2012 11:00:42 -0400 X-IronPort-AV: E=Sophos;i="4.75,637,1330934400"; d="scan'208";a="649433237" From: "Myklebust, Trond" To: Stanislav Kinsbursky CC: "linux-nfs@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devel@openvz.org" Subject: Re: [PATCH] NFS: init client before declaration Thread-Topic: [PATCH] NFS: init client before declaration Thread-Index: AQHNOBgchN+45TnxmEuX3jdeWgHLc5bWU9EAgAAIiAA= Date: Tue, 22 May 2012 15:00:17 +0000 Message-ID: <1337698816.4269.15.camel@lade.trondhjem.org> References: <20120522124018.338.20817.stgit@localhost.localdomain> <1337696984.4269.4.camel@lade.trondhjem.org> In-Reply-To: <1337696984.4269.4.camel@lade.trondhjem.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.104.60.115] Content-Type: text/plain; charset="utf-8" Content-ID: <07CAB8D0164E214F8575E78072FEE78A@tahoe.netapp.com> MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id q4MF0sWZ017861 On Tue, 2012-05-22 at 10:29 -0400, Trond Myklebust wrote: > On Tue, 2012-05-22 at 16:40 +0400, Stanislav Kinsbursky wrote: > > Client have to be initialized prior to adding it to per-net clients list, > > because otherwise there are races, shown below: > > > > CPU#0 CPU#1 > > _____ _____ > > > > nfs_get_client > > nfs_alloc_client > > list_add(..., nfs_client_list) > > rpc_fill_super > > rpc_pipefs_event > > nfs_get_client_for_event > > __rpc_pipefs_event > > (clp->cl_rpcclient is uninitialized) > > BUG() > > init_client > > clp->cl_rpcclient = ... > > > > Why not simply change nfs_get_client_for_event() so that it doesn't > touch nfs_clients that have clp->cl_cons_state!=NFS_CS_READY? > > That should ensure that it doesn't touch nfs_clients that failed to > initialise and/or are still in the process of being initialised. ...actually, come to think of it. Why not just add a helper function "bool nfs_client_active(const struct nfs_client *clp)" to fs/nfs/client.c that does a call to wait_event_killable(nfs_client_active_wq, clp->cl_cons_state < NFS_CS_INITING); and checks the resulting value of clp->cl_cons_state? -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I