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

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Date:   Fri, 16 Jul 2021 19:21:53 +0200
From:   Jon Nettleton <jon@...id-run.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Laurentiu Tudor <laurentiu.tudor@....com>,
        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 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 ?

@@ -1149,7 +1147,6 @@ int software_node_notify(struct device *dev,
unsigned long action)

                if (swnode->managed) {
                        set_secondary_fwnode(dev, NULL);
-                       kobject_put(&swnode->kobj);
                }
                break;
        default:

If we aren't being incremented in device_create_managed_software_node() then
should we be decremented here?

-Jon