From mboxrd@z Thu Jan 1 00:00:00 1970 From: "J. Bruce Fields" Subject: Re: [PATCH 5/9] rpc: call release_pipe only on last close Date: Mon, 10 Nov 2008 14:49:00 -0500 Message-ID: <20081110194900.GD19053@fieldses.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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: aglo@citi.umich.edu, kwc@citi.umich.edu, linux-nfs@vger.kernel.org To: Trond Myklebust Return-path: Received: from mail.fieldses.org ([66.93.2.214]:43517 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751143AbYKJTtE (ORCPT ); Mon, 10 Nov 2008 14:49:04 -0500 In-Reply-To: <1226344297.7599.41.camel-rJ7iovZKK19ZJLDQqaL3InhyD016LWXt@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: 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. So my patch description was wrong: "last close" should be something like "last close, or destruction of an opened pipe." I'll fix that. --b.