linux-kernel - Re: v5.13-rcX regression - NULL pointer dereference

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Message-ID: <YNBsB6zIo4A4vD4w@kuha.fi.intel.com>
Date:   Mon, 21 Jun 2021 13:37:59 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Dominik Brodowski <linux@...inikbrodowski.net>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: v5.13-rcX regression - NULL pointer dereference - MFD and
 software node API

On Mon, Jun 21, 2021 at 01:00:06PM +0300, Andy Shevchenko wrote:
> Can you, please, attach this to the bug report?
> 
> Long story here is that the device creation fails but we already have added
> swnode to it. Meanwhile, device itself is not completely instantiated (yet)
> and dev_name(dev) is NULL. The software_node_notify() is called with such
> device and Oopses in the following line
> 
> 	sysfs_remove_link(&swnode->kobj, dev_name(dev));
> 
> My patch fixes another issue that might happen before this and in the code
> that retrieves swnode itself in the device_remove_software_node().
> 
> Of course my patch won't fix this issue.
> 
> I have heard that Heikki is looking how to fix the issue in your case and
> potentially in any other cases where device_add_software_node() is called
> against not formed object instance.

Dominik, can you test the attached patch to confirm if this really is
the case.

thanks,

-- 
heikki

View attachment "0001-software-node-Handle-software-node-injection-to-an-e.patch" of type "text/plain" (1761 bytes)