From: Trond Myklebust Subject: Re: [PATCH 5/9] rpc: call release_pipe only on last close Date: Mon, 10 Nov 2008 15:01:19 -0500 Message-ID: <1226347279.7599.47.camel@heimdal.trondhjem.org> References: <20081109204621.GD27376@fieldses.org> <1226264683-28650-1-git-send-email-bfields@citi.umich.edu> <1226264683-28650-2-git-send-email-bfields@citi.umich.edu> <1226264683-28650-3-git-send-email-bfields@citi.umich.edu> <1226264683-28650-4-git-send-email-bfields@citi.umich.edu> <1226264683-28650-5-git-send-email-bfields@citi.umich.edu> <1226264683-28650-6-git-send-email-bfields@citi.umich.edu> <1226344297.7599.41.camel@heimdal.trondhjem.org> <20081110194900.GD19053@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain Cc: aglo@citi.umich.edu, kwc@citi.umich.edu, linux-nfs@vger.kernel.org To: "J. Bruce Fields" Return-path: Received: from mx2.netapp.com ([216.240.18.37]:10383 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751158AbYKJUBn (ORCPT ); Mon, 10 Nov 2008 15:01:43 -0500 In-Reply-To: <20081110194900.GD19053@fieldses.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, 2008-11-10 at 14:49 -0500, J. Bruce Fields wrote: > On Mon, Nov 10, 2008 at 02:11:37PM -0500, Trond Myklebust wrote: > > On Sun, 2008-11-09 at 16:04 -0500, J. Bruce Fields wrote: > > > I can't see any reason we particularly need to call this until the last > > > gssd closes the pipe. > > > > There's a very good reason: if we call rpc_close_pipes() then it is > > because the kernel listener is shutting down. At that point, we want to > > return EPIPE for all future read() or write() attempts by gssd. > > Sure. This doesn't interfere with that--we're still calling > release_pipe() itself (which is the function that sets rpci->ops to > NULL), it's only the ->release_pipe() op that we're not calling. > > > > Also, this allows to guarantee that open_pipe and release_pipe are > > > called strictly in pairs; open_pipe on the first open, release_pipe on > > > the last close. That'll make it very easy for the gss code to keep > > > track of which pipes gssd is using. > > > > ...unless the gss code is no longer running. > > I'm not following you. > > Note the patch calls ->release_pipe() at close_pipe() time if there are > still opens (and then subsequent closes become no-ops). So it does > guarantee that there's always a matching call. No it doesn't. Now that rpci->ops has been set to NULL by rpc_close_pipes(), exactly how are you going to call rpci->ops->release_pipe() at a later time? -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com