From: Jesper Dangaard Brouer Subject: Re: [PATCH 5/5] sunrpc/auth_gss: Call rcu_barrier() on module unload. Date: Mon, 8 Jun 2009 21:48:54 +0200 (CEST) Message-ID: References: <20090608130959.10052.54590.stgit@localhost> <20090608131148.10052.39869.stgit@localhost> <20090608162656.GF6961@linux.vnet.ibm.com> <1244480449.5040.4.camel@heimdal.trondhjem.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: paulmck@linux.vnet.ibm.com, Jesper Dangaard Brouer , netdev , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, kernel-janitors@vger.kernel.org To: Trond Myklebust Return-path: Received: from mgw1.diku.dk ([130.225.96.91]:48891 "EHLO mgw1.diku.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750758AbZFHTtl (ORCPT ); Mon, 8 Jun 2009 15:49:41 -0400 In-Reply-To: <1244480449.5040.4.camel-rJ7iovZKK19ZJLDQqaL3InhyD016LWXt@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: (trimmed Cc) On Mon, 8 Jun 2009, Trond Myklebust wrote: > Hmm... If this is about ensuring that all the call_rcu() callbacks > complete before we remove the module, then don't we also need similar > barriers in Well, Trond that was a hard question, as I don't know this code... but if it uses call_rcu() callbacks its most likely. I have not done a complete sweep of the tree, I have only looked at the netdev parts, as this is where I usually snoop around. So there is probably plenty of work for some kernel-janitors (Cc'ing the list ;-)) > net/sunrpc/sunrpc_syms.c:cleanup_sunrpc() Looking at the code that end up in sunrpc.ko, I see that both net/sunrpc/auth_unix.c and net/sunrpc/auth_generic.c uses call_rcu() callbacks. > and in fs/nfs/inode.c:exit_nfs_fs()? Looking at the code which end up into nfs.ko (which includes fs/nfs/inode.c) I see that the fs/nfs/delegation.c uses call_rcu() callbacks. But its hard for me to figure out how this code interacts. Don't know if we need to document a code path that can occur fast enough, before we add this safe guard? It should be Paul's saying... Cheers, Jesper Brouer -- ------------------------------------------------------------------- MSc. Master of Computer Science Dept. of Computer Science, University of Copenhagen Author of http://www.adsl-optimizer.dk -------------------------------------------------------------------