From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E903C433DF for ; Thu, 4 Jun 2020 20:15:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78AD32067B for ; Thu, 4 Jun 2020 20:15:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591301727; bh=nh6iqP7pKii9WtoysGEakHtXlKm8WZrihRzKio25mpw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Orpy+iPAWgEM4vwaHxWtgi7COQmTnKtOP/F2ktaf/GknijZH8g6gn/dfASEmwOI2p c80LvL1Iz0tgO9x6ffZ0bZPmDAJvUX0vZNkLTWELL7wJ0nfzSVoFT8RgZv8h+Mfnax z08REmouMJvcn/uVto/QeKH4MDDTtfXSmqm7TLME= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727896AbgFDUP1 (ORCPT ); Thu, 4 Jun 2020 16:15:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:59570 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726666AbgFDUP0 (ORCPT ); Thu, 4 Jun 2020 16:15:26 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8086B2067B; Thu, 4 Jun 2020 20:15:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591301726; bh=nh6iqP7pKii9WtoysGEakHtXlKm8WZrihRzKio25mpw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=L0sRYQaMkF8MApvnQWJxq7PThTjN3ACXwLABb5mU8JIeqeXPe4Vt33AYljlyvHvZ9 BG0V+j+461wfVDLQNa1wln1Z3bGbIKL2SYzB9tYQ5gNPVLLvdo5pn1qIJ5CAncYGTD ZgRKqJ+Gva8WlhVQiBZe/Jm/iK1SCVekAgwqcDmI= Date: Thu, 4 Jun 2020 22:15:23 +0200 From: Greg Kroah-Hartman To: jorhand@linux.microsoft.com Cc: Heikki Krogerus , "Rafael J . Wysocki" , linux-kernel@vger.kernel.org, linux-next@vger.kernel.org Subject: Re: [PATCH] software node: recursively unregister child swnodes Message-ID: <20200604201523.GA1308830@kroah.com> References: <20200604193623.16946-1-jorhand@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200604193623.16946-1-jorhand@linux.microsoft.com> Sender: linux-next-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-next@vger.kernel.org On Thu, Jun 04, 2020 at 12:36:23PM -0700, jorhand@linux.microsoft.com wrote: > From: Jordan Hand > > If a child swnode is unregistered after it's parent, it can lead to > undefined behavior. Crashing the system is not really "undefined" :) > When a swnode is unregistered, recursively free it's children to avoid > this condition. Are you sure? Why would you be unregistering a child after it's parent? Why not just do not do that? > > Signed-off-by: Jordan Hand > --- > drivers/base/swnode.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c > index e5eb27375416..e63093b1542b 100644 > --- a/drivers/base/swnode.c > +++ b/drivers/base/swnode.c > @@ -619,6 +619,8 @@ static void software_node_release(struct kobject *kobj) > property_entries_free(swnode->node->properties); > kfree(swnode->node); > } > + > + list_del(&kobj->entry); > ida_destroy(&swnode->child_ids); > kfree(swnode); > } > @@ -712,11 +714,6 @@ EXPORT_SYMBOL_GPL(software_node_register_nodes); > * @nodes: Zero terminated array of software nodes to be unregistered > * > * Unregister multiple software nodes at once. > - * > - * NOTE: Be careful using this call if the nodes had parent pointers set up in > - * them before registering. If so, it is wiser to remove the nodes > - * individually, in the correct order (child before parent) instead of relying > - * on the sequential order of the list of nodes in the array. > */ > void software_node_unregister_nodes(const struct software_node *nodes) > { > @@ -839,10 +836,16 @@ EXPORT_SYMBOL_GPL(fwnode_create_software_node); > void fwnode_remove_software_node(struct fwnode_handle *fwnode) > { > struct swnode *swnode = to_swnode(fwnode); > + struct swnode *child = NULL; > > if (!swnode) > return; > > + while (!list_empty(&swnode->children)) { > + child = list_first_entry_or_null(&swnode->children, struct swnode, entry); > + fwnode_remove_software_node(&child->fwnode); You should document that you just changed the behaivor here, as you are now really doing fwnode_remove_software_node_and_all_children(). but again, why? Who wants to unregister a child before a parent? thanks, greg k-h