Re: v5.13-rcX regression - NULL pointer dereference - MFD and software node API

From: Dominik Brodowski <linux@dominikbrodowski.net>
To: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
	Lee Jones <lee.jones@linaro.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: v5.13-rcX regression - NULL pointer dereference - MFD and software node API
Date: Mon, 21 Jun 2021 17:31:50 +0200	[thread overview]
Message-ID: <YNCw5k9vwdQiS0u4@owl.dominikbrodowski.net> (raw)
In-Reply-To: <YNBsB6zIo4A4vD4w@kuha.fi.intel.com>

Am Mon, Jun 21, 2021 at 01:37:59PM +0300 schrieb Heikki Krogerus:
> 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.

With this patch applied, the panic disappears.

Many thanks,
	Dominik