linux-kernel - Re: [PATCH] software node: balance refcount for managed sw nodes

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Date:   Mon, 19 Jul 2021 15:00:17 +0300
From:   Laurentiu Tudor <laurentiu.tudor@....com>
To:     Jon Nettleton <jon@...id-run.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] software node: balance refcount for managed sw nodes



On 7/16/2021 8:21 PM, Jon Nettleton wrote:
> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com> wrote:
>>
>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@....com wrote:
>>> From: Laurentiu Tudor <laurentiu.tudor@....com>
>>>
>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
>>> software nodes, thus leading to underflow errors. Balance the refcount by
>>> bumping it in the device_create_managed_software_node() function.
>>>
>>> The error [1] was encountered after adding a .shutdown() op to our
>>> fsl-mc-bus driver.
>>
>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
>> later on), I can tell that probably something is wrong in the ->shutdown()
>> method itself.
>>
>> --
>> With Best Regards,
>> Andy Shevchenko
>>
>>
> 
> Isn't the other alternative to just remove the second kobject_put from
> KOBJ_REMOVE ?
> 

Or maybe on top of Heikki's suggestion, replace the calls to
sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?

---
Best Regards, Laurentiu