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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 CB51BC2BBD4 for ; Fri, 18 Dec 2020 16:03:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9664C23B78 for ; Fri, 18 Dec 2020 16:03:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728449AbgLRQC4 (ORCPT ); Fri, 18 Dec 2020 11:02:56 -0500 Received: from perceval.ideasonboard.com ([213.167.242.64]:41438 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726228AbgLRQCz (ORCPT ); Fri, 18 Dec 2020 11:02:55 -0500 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 2BDD82CF; Fri, 18 Dec 2020 17:02:12 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1608307332; bh=s2SHQA0PN7urDd/Qm3xpPmk0SAd9BjjKrvkA4hZemV4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OFxcFcRYphMYulyRHR3ufYN6rRoNVK6eIUT4lylN+2Ep7+NVgoerI/bkEwgOUO6hw 3kKeqs/9UiyviMhbz/17vdyHdsd48l6WXEfIhVNFmYIPNOhgYfC7df6hF5NykwaxoY P748LH6UxsHOv9BQDiVlWzvt0x+Vu4fjo81/1afs= Date: Fri, 18 Dec 2020 18:02:04 +0200 From: Laurent Pinchart To: Daniel Scally Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-media@vger.kernel.org, devel@acpica.org, rjw@rjwysocki.net, lenb@kernel.org, gregkh@linuxfoundation.org, yong.zhi@intel.com, sakari.ailus@linux.intel.com, bingbu.cao@intel.com, tian.shu.qiu@intel.com, mchehab@kernel.org, robert.moore@intel.com, erik.kaneda@intel.com, pmladek@suse.com, rostedt@goodmis.org, sergey.senozhatsky@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, laurent.pinchart+renesas@ideasonboard.com, jacopo+renesas@jmondi.org, kieran.bingham+renesas@ideasonboard.com, linus.walleij@linaro.org, heikki.krogerus@linux.intel.com, kitakar@gmail.com, jorhand@linux.microsoft.com Subject: Re: [PATCH v2 04/12] software_node: Enforce parent before child ordering of nodes arrays Message-ID: References: <20201217234337.1983732-1-djrscally@gmail.com> <20201217234337.1983732-5-djrscally@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201217234337.1983732-5-djrscally@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Daniel, Thank you for the patch. On Thu, Dec 17, 2020 at 11:43:29PM +0000, Daniel Scally wrote: > Registering software_nodes with the .parent member set to point to a > currently unregistered software_node has the potential for problems, > so enforce parent -> child ordering in arrays passed in to > software_node_register_nodes(). > > Software nodes that are children of another software node should be > unregistered before their parent. To allow easy unregistering of an array > of software_nodes ordered parent to child, reverse the order in which > software_node_unregister_nodes() unregisters software_nodes. > > Suggested-by: Andy Shevchenko > Signed-off-by: Daniel Scally > --- > Changes in v2: > > - Squashed the patches that originally touched these separately > - Updated documentation > > drivers/base/swnode.c | 43 ++++++++++++++++++++++++++++++------------- > 1 file changed, 30 insertions(+), 13 deletions(-) > > diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c > index 615a0c93e116..cfd1faea48a7 100644 > --- a/drivers/base/swnode.c > +++ b/drivers/base/swnode.c > @@ -692,7 +692,10 @@ swnode_register(const struct software_node *node, struct swnode *parent, > * software_node_register_nodes - Register an array of software nodes > * @nodes: Zero terminated array of software nodes to be registered > * > - * Register multiple software nodes at once. > + * Register multiple software nodes at once. If any node in the array > + * has it's .parent pointer set, then it's parent **must** have been > + * registered before it is; either outside of this function or by > + * ordering the array such that parent comes before child. > */ > int software_node_register_nodes(const struct software_node *nodes) > { > @@ -700,33 +703,47 @@ int software_node_register_nodes(const struct software_node *nodes) > int i; > > for (i = 0; nodes[i].name; i++) { > - ret = software_node_register(&nodes[i]); > - if (ret) { > - software_node_unregister_nodes(nodes); > - return ret; > + const struct software_node *parent = nodes[i].parent; > + > + if (parent && !software_node_to_swnode(parent)) { > + ret = -EINVAL; > + goto err_unregister_nodes; > } > + > + ret = software_node_register(&nodes[i]); > + if (ret) > + goto err_unregister_nodes; > } > > return 0; > + > +err_unregister_nodes: > + software_node_unregister_nodes(nodes); > + return ret; > } > EXPORT_SYMBOL_GPL(software_node_register_nodes); > > /** > * software_node_unregister_nodes - Unregister an array of software nodes > - * @nodes: Zero terminated array of software nodes to be unregistered > + * @nodes: Zero terminated array of software nodes to be unregistered. Not sure if this is needed. > * > - * Unregister multiple software nodes at once. > + * Unregister multiple software nodes at once. If parent pointers are set up > + * in any of the software nodes then the array MUST be ordered such that I'd either replace **must** above with MUST, or use **must** here. I'm not sure if kerneldoc handles emphasis with **must**, if it does that seems a bit nicer to me, but it's really up to you. Reviewed-by: Laurent Pinchart > + * parents come before their children. > * > - * 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. > + * NOTE: If you are uncertain whether the array is ordered such that > + * parents will be unregistered before their children, it is wiser to > + * remove the nodes individually, in the correct order (child before > + * parent). > */ > void software_node_unregister_nodes(const struct software_node *nodes) > { > - int i; > + unsigned int i = 0; > + > + while (nodes[i].name) > + i++; > > - for (i = 0; nodes[i].name; i++) > + while (i--) > software_node_unregister(&nodes[i]); > } > EXPORT_SYMBOL_GPL(software_node_unregister_nodes); -- Regards, Laurent Pinchart