linux-kernel - Re: [PATCH v2] device property: fix of node refcount leak in fwnode_graph_get_next

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Message-ID: <26c0d10a-5dd8-6cea-57b3-eea63099baa1@huawei.com>
Date:   Tue, 22 Nov 2022 21:41:28 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <djrscally@...il.com>, <heikki.krogerus@...ux.intel.com>,
        <sakari.ailus@...ux.intel.com>, <gregkh@...uxfoundation.org>,
        <rafael@...nel.org>
Subject: Re: [PATCH v2] device property: fix of node refcount leak in
 fwnode_graph_get_next_endpoint()


On 2022/11/22 21:16, Andy Shevchenko wrote:
> On Tue, Nov 22, 2022 at 09:12:41PM +0800, Yang Yingliang wrote:
>> On 2022/11/22 20:54, Andy Shevchenko wrote:
>>> On Tue, Nov 22, 2022 at 08:00:39PM +0800, Yang Yingliang wrote:
> ...
>
>>> It seems too complicated for the simple fix.
>>>
>>> As I said, just drop const qualifier and add fwnode_handle_get() in the 'else'
>>> branch. This will allow you to drop if (prev) at the end.
>> fwnode is const, fwnode_handle_get doesn't accept this type.
> I'm talking about parent.
You suggested this:

"Instead you might consider to replace

	parent = fwnode;

by

	parent = fwnode_handle_get(fwnode);"


It has compile warning:
drivers/base/property.c: In function ‘fwnode_graph_get_next_endpoint’:
drivers/base/property.c:1004:30: warning: passing argument 1 of ‘fwnode_handle_get’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
    parent = fwnode_handle_get(fwnode);
                               ^~~~~~
drivers/base/property.c:809:63: note: expected ‘struct fwnode_handle *’ but argument is of type ‘const struct fwnode_handle *’
  struct fwnode_handle *fwnode_handle_get(struct fwnode_handle *fwnode)

~~~~~~~~~~~~~~~~~~~~~~^~~~~~