From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933113AbXBGBxN (ORCPT ); Tue, 6 Feb 2007 20:53:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933218AbXBGBxN (ORCPT ); Tue, 6 Feb 2007 20:53:13 -0500 Received: from smtp.osdl.org ([65.172.181.24]:58842 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933113AbXBGBxM (ORCPT ); Tue, 6 Feb 2007 20:53:12 -0500 Date: Tue, 6 Feb 2007 17:51:52 -0800 From: Andrew Morton To: NeilBrown Cc: stable@kernel.org, nfs@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH] knfsd: Fix a race in closing NFSd connections. Message-Id: <20070206175152.39d767dd.akpm@linux-foundation.org> In-Reply-To: <1070207001026.9413@suse.de> References: <20070207110636.9166.patches@notabene> <1070207001026.9413@suse.de> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 7 Feb 2007 11:10:26 +1100 NeilBrown wrote: > If you lose this race, it can iput a socket inode twice and you > get a BUG in fs/inode.c > > When I added the option for user-space to close a socket, > I added some cruft to svc_delete_socket so that I could call > that function when closing a socket per user-space request. > > This was the wrong thing to do. I should have just set SK_CLOSE > and let normal mechanisms do the work. > > Not only wrong, but buggy. The locking is all wrong and it openned > up a race where-by a socket could be closed twice. > > So this patch: > Introduces svc_close_socket which sets SK_CLOSE then either leave > the close up to a thread, or calls svc_delete_socket if it can > get SK_BUSY. > > Adds a bias to sk_busy which is removed when SK_DEAD is set, > This avoid races around shutting down the socket. > > Changes several 'spin_lock' to 'spin_lock_bh' where the _bh > was missing. > This patch assumes the presence of knfsd-sunrpc-allow-creating-an-rpc-service-without-registering-with-portmapper.patch which obviously isn't appropriate for -stable. Please confirm that the patch which I merged is still OK, thanks.