Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753112AbbBRRDz (ORCPT ); Wed, 18 Feb 2015 12:03:55 -0500 Received: from cantor2.suse.de ([195.135.220.15]:51254 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752205AbbBRRDx (ORCPT ); Wed, 18 Feb 2015 12:03:53 -0500 Date: Wed, 18 Feb 2015 18:03:48 +0100 From: Petr Mladek To: Miroslav Benes Cc: Josh Poimboeuf , Seth Jennings , Jiri Kosina , Vojtech Pavlik , Masami Hiramatsu , live-patching@vger.kernel.org, Linux Kernel Mailing List Subject: Re: [RFC PATCH 1/9] livepatch: simplify disable error path Message-ID: <20150218170348.GF2639@dhcp128.suse.cz> References: <0635ea962de795d565b3ea04ca640c13f6145775.1423499826.git.jpoimboe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: 5818 Lines: 187 On Fri 2015-02-13 13:25:35, Miroslav Benes wrote: > On Mon, 9 Feb 2015, Josh Poimboeuf wrote: > > > If registering the function with ftrace has previously succeeded, > > unregistering will almost never fail. Even if it does, it's not a fatal > > error. We can still carry on and disable the klp_func from being used > > by removing it from the klp_ops func stack. > > > > Signed-off-by: Josh Poimboeuf > > This makes sense, so > > Reviewed-by: Miroslav Benes > > I think this patch could be taken independently of the consistency model. > If no one else has any objection... Yup, it looks good to me. Reviewed-by: Petr Mladek > Miroslav > > > --- > > kernel/livepatch/core.c | 67 +++++++++++++------------------------------------ > > 1 file changed, 17 insertions(+), 50 deletions(-) > > > > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > > index 9adf86b..081df77 100644 > > --- a/kernel/livepatch/core.c > > +++ b/kernel/livepatch/core.c > > @@ -322,32 +322,20 @@ static void notrace klp_ftrace_handler(unsigned long ip, > > klp_arch_set_pc(regs, (unsigned long)func->new_func); > > } > > > > -static int klp_disable_func(struct klp_func *func) > > +static void klp_disable_func(struct klp_func *func) > > { > > struct klp_ops *ops; > > - int ret; > > - > > - if (WARN_ON(func->state != KLP_ENABLED)) > > - return -EINVAL; > > > > - if (WARN_ON(!func->old_addr)) > > - return -EINVAL; > > + WARN_ON(func->state != KLP_ENABLED); > > + WARN_ON(!func->old_addr); > > > > ops = klp_find_ops(func->old_addr); > > if (WARN_ON(!ops)) > > - return -EINVAL; > > + return; > > > > if (list_is_singular(&ops->func_stack)) { > > - ret = unregister_ftrace_function(&ops->fops); > > - if (ret) { > > - pr_err("failed to unregister ftrace handler for function '%s' (%d)\n", > > - func->old_name, ret); > > - return ret; > > - } > > - > > - ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0); > > - if (ret) > > - pr_warn("function unregister succeeded but failed to clear the filter\n"); > > + WARN_ON(unregister_ftrace_function(&ops->fops)); > > + WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0)); > > > > list_del_rcu(&func->stack_node); > > list_del(&ops->node); > > @@ -357,8 +345,6 @@ static int klp_disable_func(struct klp_func *func) > > } > > > > func->state = KLP_DISABLED; > > - > > - return 0; > > } > > > > static int klp_enable_func(struct klp_func *func) > > @@ -419,23 +405,15 @@ err: > > return ret; > > } > > > > -static int klp_disable_object(struct klp_object *obj) > > +static void klp_disable_object(struct klp_object *obj) > > { > > struct klp_func *func; > > - int ret; > > > > - for (func = obj->funcs; func->old_name; func++) { > > - if (func->state != KLP_ENABLED) > > - continue; > > - > > - ret = klp_disable_func(func); > > - if (ret) > > - return ret; > > - } > > + for (func = obj->funcs; func->old_name; func++) > > + if (func->state == KLP_ENABLED) > > + klp_disable_func(func); > > > > obj->state = KLP_DISABLED; > > - > > - return 0; > > } > > > > static int klp_enable_object(struct klp_object *obj) > > @@ -451,22 +429,19 @@ static int klp_enable_object(struct klp_object *obj) > > > > for (func = obj->funcs; func->old_name; func++) { > > ret = klp_enable_func(func); > > - if (ret) > > - goto unregister; > > + if (ret) { > > + klp_disable_object(obj); > > + return ret; > > + } > > } > > obj->state = KLP_ENABLED; > > > > return 0; > > - > > -unregister: > > - WARN_ON(klp_disable_object(obj)); > > - return ret; > > } > > > > static int __klp_disable_patch(struct klp_patch *patch) > > { > > struct klp_object *obj; > > - int ret; > > > > /* enforce stacking: only the last enabled patch can be disabled */ > > if (!list_is_last(&patch->list, &klp_patches) && > > @@ -476,12 +451,8 @@ static int __klp_disable_patch(struct klp_patch *patch) > > pr_notice("disabling patch '%s'\n", patch->mod->name); > > > > for (obj = patch->objs; obj->funcs; obj++) { > > - if (obj->state != KLP_ENABLED) > > - continue; > > - > > - ret = klp_disable_object(obj); > > - if (ret) > > - return ret; > > + if (obj->state == KLP_ENABLED) > > + klp_disable_object(obj); > > } > > > > patch->state = KLP_DISABLED; > > @@ -931,7 +902,6 @@ static void klp_module_notify_going(struct klp_patch *patch, > > { > > struct module *pmod = patch->mod; > > struct module *mod = obj->mod; > > - int ret; > > > > if (patch->state == KLP_DISABLED) > > goto disabled; > > @@ -939,10 +909,7 @@ static void klp_module_notify_going(struct klp_patch *patch, > > pr_notice("reverting patch '%s' on unloading module '%s'\n", > > pmod->name, mod->name); > > > > - ret = klp_disable_object(obj); > > - if (ret) > > - pr_warn("failed to revert patch '%s' on module '%s' (%d)\n", > > - pmod->name, mod->name, ret); > > + klp_disable_object(obj); > > > > disabled: > > klp_free_object_loaded(obj); > > -- > > 2.1.0 > > > > -- > > 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/ > > > -- > To unsubscribe from this list: send the line "unsubscribe live-patching" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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/