Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755208Ab3DODu0 (ORCPT ); Sun, 14 Apr 2013 23:50:26 -0400 Received: from ozlabs.org ([203.10.76.45]:59181 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754933Ab3DODuX (ORCPT ); Sun, 14 Apr 2013 23:50:23 -0400 From: Rusty Russell To: Veaceslav Falico Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, gregkh@linuxfoundation.org, bhelgaas@google.com Subject: Re: [PATCH] module: add kset_obj_exists() and use it In-Reply-To: <20130411095537.GC21320@redhat.com> References: <1365506529-8396-1-git-send-email-vfalico@redhat.com> <87y5cq6ei9.fsf@rustcorp.com.au> <20130411095537.GC21320@redhat.com> User-Agent: Notmuch/0.14 (http://notmuchmail.org) Emacs/23.4.1 (i686-pc-linux-gnu) Date: Mon, 15 Apr 2013 11:56:03 +0930 Message-ID: <87vc7o8r7o.fsf@rustcorp.com.au> 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 Content-Length: 3056 Lines: 100 Veaceslav Falico writes: > On Wed, Apr 10, 2013 at 04:47:34PM +0930, Rusty Russell wrote: >>That's a bug. We should be cleaning up sysfs before we unlike the >>removed module from the list. >> >>Because the same thing applies to ddebug info, which is also keyed by >>module name. >> >>Something like this (untested!): > > Sorry for the late response - I wanted to test it for a longer time. > > Your patch works flawlessly and fixes this race, with just a small > addition, cause otherwise we could BUG() in show_initstate(). > > Can you apply this patch or should I (re-)send it somehow? > > Thank you! > > diff --git a/kernel/module.c b/kernel/module.c > index d0afe23..8be6e97 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -1063,6 +1063,9 @@ static ssize_t show_initstate(struct module_attribute *mattr, > case MODULE_STATE_GOING: > state = "going"; > break; > + case MODULE_STATE_UNFORMED: > + state = "unformed"; > + break; > default: > BUG(); > } Prefer to remove from sysfs before marking it unformed, like so: diff --git a/kernel/module.c b/kernel/module.c index 2468fda..2e7189f 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1862,12 +1862,12 @@ static void free_module(struct module *mod) { trace_module_free(mod); - /* We leave it in list to prevent duplicate loads while we clean - * up sysfs, ddebug and any other external exposure. */ - mod->state = MODULE_STATE_UNFORMED; - mod_sysfs_teardown(mod); + /* We leave it in list to prevent duplicate loads, but make sure + * that noone uses it while it's being deconstructed. */ + mod->state = MODULE_STATE_UNFORMED; + /* Remove dynamic debug info */ ddebug_remove_module(mod->name); Here's the updated total patch: diff --git a/kernel/module.c b/kernel/module.c index 69d2600..2e7189f 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1862,12 +1862,12 @@ static void free_module(struct module *mod) { trace_module_free(mod); - /* Delete from various lists */ - mutex_lock(&module_mutex); - stop_machine(__unlink_module, mod, NULL); - mutex_unlock(&module_mutex); mod_sysfs_teardown(mod); + /* We leave it in list to prevent duplicate loads, but make sure + * that noone uses it while it's being deconstructed. */ + mod->state = MODULE_STATE_UNFORMED; + /* Remove dynamic debug info */ ddebug_remove_module(mod->name); @@ -1880,6 +1880,11 @@ static void free_module(struct module *mod) /* Free any allocated parameters. */ destroy_params(mod->kp, mod->num_kp); + /* Now we can delete it from the lists */ + mutex_lock(&module_mutex); + stop_machine(__unlink_module, mod, NULL); + mutex_unlock(&module_mutex); + /* This may be NULL, but that's OK */ unset_module_init_ro_nx(mod); module_free(mod, mod->module_init); Thanks, Rusty. -- 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/