From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753467AbbDAONf (ORCPT ); Wed, 1 Apr 2015 10:13:35 -0400 Received: from cantor2.suse.de ([195.135.220.15]:57038 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753209AbbDAONd (ORCPT ); Wed, 1 Apr 2015 10:13:33 -0400 Date: Wed, 1 Apr 2015 16:13:31 +0200 (CEST) From: Jiri Kosina To: Minfei Huang cc: jpoimboe@redhat.com, sjenning@redhat.com, vojtech@suse.cz, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] livepatch: Enhance livepatch to support remove patch module dynamically In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 1 Apr 2015, Minfei Huang wrote: > > > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > > > index 3f9f1d6..0266950 100644 > > > --- a/kernel/livepatch/core.c > > > +++ b/kernel/livepatch/core.c > > > @@ -502,6 +502,17 @@ static int __klp_disable_patch(struct klp_patch *patch) > > > return 0; > > > } > > > > > > +static int __klp_disable_patch_nolock(struct klp_patch *patch) > > > +{ > > > + int ret = 0; > > > + > > > + ret = __klp_disable_patch(patch); > > > + if (ret) > > > + return ret; > > > + module_put(patch->mod); > > > + return ret; > > > +} > > > + > > > > Your patch doesn't solve the problem at all. > > > > There is no guarantee that once __klp_disable_patch() returns noone is > > using the old code any more. > > > > Yes, thanks. > > The __klp_disable_patch only guarantees that we will never call the > function in patch module. For now, patch module can never be removed > from the kernel once it was loaded. It may be inconvenience if we want > re-load a new patch module replace the old patch module. Patch stacking is possible though. -- Jiri Kosina SUSE Labs