Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753123AbbERPdR (ORCPT ); Mon, 18 May 2015 11:33:17 -0400 Received: from cantor2.suse.de ([195.135.220.15]:53927 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932160AbbERPdJ (ORCPT ); Mon, 18 May 2015 11:33:09 -0400 Date: Mon, 18 May 2015 17:35:49 +0200 From: Petr Mladek To: Minfei Huang Cc: Josh Poimboeuf , Minfei Huang , mbenes@suse.cz, sjenning@redhat.com, jkosina@suse.cz, vojtech@suse.cz, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] livepatch: Prevent to apply the patch once coming module notifier fails Message-ID: <20150518153549.GF2632@pathway.suse.cz> References: <1431439484-44530-1-git-send-email-mnfhuang@gmail.com> <20150513141415.GB28284@treble.redhat.com> <20150518120806.GC2632@pathway.suse.cz> <20150518130057.GA25260@dhcp-128-1.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150518130057.GA25260@dhcp-128-1.nay.redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5240 Lines: 142 On Mon 2015-05-18 21:00:57, Minfei Huang wrote: > On 05/18/15 at 02:08pm, Petr Mladek wrote: > > On Wed 2015-05-13 09:14:15, Josh Poimboeuf wrote: > > > On Tue, May 12, 2015 at 10:04:44PM +0800, Minfei Huang wrote: > > > > @@ -883,7 +883,7 @@ int klp_register_patch(struct klp_patch *patch) > > > > } > > > > EXPORT_SYMBOL_GPL(klp_register_patch); > > > > > > > > -static void klp_module_notify_coming(struct klp_patch *patch, > > > > +static int klp_module_notify_coming(struct klp_patch *patch, > > > > struct klp_object *obj) > > > > { > > > > struct module *pmod = patch->mod; > > > > @@ -891,22 +891,24 @@ static void klp_module_notify_coming(struct klp_patch *patch, > > > > int ret; > > > > > > > > ret = klp_init_object_loaded(patch, obj); > > > > - if (ret) > > > > - goto err; > > > > + if (ret) { > > > > + pr_warn("failed to initialize the patch '%s' (%d)\n", > > > > + pmod->name, ret); > > > > + goto out; > > > > + } > > > > > > Can you change it to: > > > > > > "failed to initialize the patch '%s' for module '%s' (%d)\n" ? > > > > > > That would make it more consistent with the other error message and > > > identify the failing module. > > > > > > Also, the indentation should be fixed on the second pr_warn() line. > > > > > > > > > > > if (patch->state == KLP_DISABLED) > > > > - return; > > > > + goto out; > > > > > > > > pr_notice("applying patch '%s' to loading module '%s'\n", > > > > pmod->name, mod->name); > > > > > > > > ret = klp_enable_object(obj); > > > > - if (!ret) > > > > - return; > > > > - > > > > -err: > > > > - pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", > > > > - pmod->name, mod->name, ret); > > > > + if (ret) > > > > + pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", > > > > + pmod->name, mod->name, ret); > > > > > > Bad indentation here too. > > > > > > > @@ -930,6 +932,7 @@ disabled: > > > > static int klp_module_notify(struct notifier_block *nb, unsigned long action, > > > > void *data) > > > > { > > > > + int ret; > > > > struct module *mod = data; > > > > struct klp_patch *patch; > > > > struct klp_object *obj; > > > > @@ -955,7 +958,13 @@ static int klp_module_notify(struct notifier_block *nb, unsigned long action, > > > > > > > > if (action == MODULE_STATE_COMING) { > > > > obj->mod = mod; > > > > - klp_module_notify_coming(patch, obj); > > > > + ret = klp_module_notify_coming(patch, obj); > > > > + if (ret) { > > > > + obj->mod = NULL; > > > > + pr_warn("patch '%s' is dead, remove it " > > > > + "or re-install the module '%s'\n", > > > > + patch->mod->name, obj->name); > > > > + } > > > > > > The patch isn't necessarily dead, since it might also include previously > > > enabled changes for vmlinux or other modules. It can actually be a > > > dangerous condition if there's a mismatch between old code in the module > > > and new code elsewhere. How about something like: > > > > > > "patch '%s' is in an inconsistent state!\n" > > > > It must not be dangerous, otherwise the patch could not get applied > > immediately. > > But kernel is in dangerous situation that the patch may corrupt it > later. So it is appropriate to notify the user. How exactly could the patch corrupt the system? Could you please give an example? > > > > I would omit this message completely. It would just duplicate the > > warning printed by klp_module_notify_coming(). > > > > This error message aims to tell this fact that this patch is in an > inconsistent state. If someone do not notify this error, it is fine, > because the inconsistent patch does not have change to be applied to the > kernel. But there is already printed a warning from klp_module_notify_coming(). I wonder why we need one more here. > > > > > Also, there's no need to split up the string literal into two lines. > > > It's ok for a line to have more than 80 columns in that case. > > > > I suggest to run ./scripts/chechpatch.pl before you send any patch. > > It would catch the indentation problems, split of the string, ... > > I have used the script checkpatch.pl to verify the patch. And it passed > for the checking. About the indentation problems, it may be caused by > the sepcified vimrc file. I get the following warning on your patch: --- cut --- $> ./scripts/checkpatch.pl /prace/klp-module-notify-error-v3-iter1.patch WARNING: quoted string split across lines #181: FILE: kernel/livepatch/core.c:965: + pr_warn("patch '%s' is dead, remove it " + "or re-install the module '%s'\n", total: 0 errors, 1 warnings, 62 lines checked /prace/klp-module-notify-error-v3-iter1.patch has style problems, please review. If any of these errors are false positives, please report them to the maintainer, see CHECKPATCH in MAINTAINERS. --- cut --- BTW: I do not see the problems with indentation. Best Regards, Petr -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/