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Wed, 21 Oct 2020 02:56:02 -0700 (PDT) Subject: Re: [RFC PATCH v3 3/9] software_node: Fix failure to hold refcount in software_node_get_next_child To: Andy Shevchenko Cc: Sakari Ailus , linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux.walleij@linaro.org, prabhakar.mahadev-lad.rj@bp.renesas.com, heikki.krogerus@linux.intel.com, dmitry.torokhov@gmail.com, laurent.pinchart+renesas@ideasonboard.com, kieran.bingham+renesas@ideasonboard.com, jacopo+renesas@jmondi.org, robh@kernel.org, davem@davemloft.net, linux@rasmusvillemoes.dk, sergey.senozhatsky@gmail.com, rostedt@goodmis.org, pmladek@suse.com, mchehab@kernel.org, tian.shu.qiu@intel.com, bingbu.cao@intel.com, sakari.ailus@linux.intel.com, yong.zhi@intel.com, rafael@kernel.org, gregkh@linuxfoundation.org, kitakar@gmail.com, dan.carpenter@oracle.org References: <20201019225903.14276-1-djrscally@gmail.com> <20201019225903.14276-4-djrscally@gmail.com> <20201020133148.GB843@valkosipuli.retiisi.org.uk> <20201021093321.GM4077@smile.fi.intel.com> From: Dan Scally Message-ID: Date: Wed, 21 Oct 2020 10:56:01 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201021093321.GM4077@smile.fi.intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 21/10/2020 10:33, Andy Shevchenko wrote: > On Wed, Oct 21, 2020 at 12:25:28AM +0100, Dan Scally wrote: >> On 20/10/2020 14:31, Sakari Ailus wrote: >>> On Mon, Oct 19, 2020 at 11:58:57PM +0100, Daniel Scally wrote: >>>> + return software_node_get(&c->fwnode); >>> I believe similarly, the function should drop the reference to the previous >>> node, and not expect the caller to do this. The OF equivalent does the >>> same. >> I think I prefer it this way myself, since the alternative is having to >> explicitly call *_node_get() on a returned child if you want to keep it >> but also keep iterating. But I agree that it's important to take a >> consistent approach. I'll add that too; this will mean >> swnode_graph_find_next_port() and >> software_node_graph_get_next_endpoint() in patch 4 of this series will >> need changing slightly to square away their references. > What about ACPI case? Does it square? ACPI version doesn't handle references at all; neither puts() the old nor gets() the new child node.