Re: [PATCH 2/3] spi: pxa2xx: Fix controller unregister order

[Tsuchiya Yuto <kitakar@gmail.com>]

I tried a kernel built with the prerequisite patch to this series + all
of patches in this series on top of v5.7-rc7 (with Arch Linux config
+ olddefconfig).

Current situations on 5.7-rc7 with Arch Linux config + olddefconfig
(without applying this series):
- I can reproduce the touch input crashing (surface3-spi) I mentioned
  in bugzilla [1] only after s2idle.
- all the other situations are the same as described in that bugzilla;
  I see NULL pointer dereference [2] after touch input crashing then try
  to unload only spi_pxa2xx_platform module.

So, the steps to test that I did with this series applied are:
1. go into s2idle then resume from s2idle
2. make a touch input then surface3-spi reports that "SPI transfer
   timed out" repeatedly and no longer responds to any touch input
3. try to unload only spi_pxa2xx_platform module and see if the NULL
   pointer dereference no longer occurs

and I can confirm that I no longer see the NULL pointer dereference.
Thanks!

On 5/26/20 5:22 PM, Andy Shevchenko wrote:
> On Tue, May 26, 2020 at 09:39:13AM +0200, Lukas Wunner wrote:
>> On Mon, May 25, 2020 at 04:21:43PM +0300, Andy Shevchenko wrote:
>>> Tsuchiya Yuto, I'm going to apply this series as preparatory to my
>>> WIP patch in topic/spi/reload branch in my kernel tree on GitHub,
>>> so, it would be possible to see if this + my patch fixes crashes
>>> on removal. Though, please test this separately from my stuff to
>>> clarify if it fixes or not issue you have seen.
>> You also need to cherry-pick commit 84855678add8 ("spi: Fix controller
>> unregister order") from spi/for-next onto your topic/spi/reload branch
>> for reloading to work correctly.
>>
>> Alternatively, rebase your topic/spi/reload branch and redo the merge
>> from spi/for-next.  (You've merged spi/for-next into your branch on
>> May 14, but the commit was applied by Mark on May 20.)
> Ah, right. Will do it soon.

I also built a kernel against your branch topic/spi/reload
(permalink: https://github.com/andy-shev/linux/tree/55cb78d5a752). The
result is the same as only applying this series; so, to fix the NULL pointer
dereference that I mentioned in bugzilla [2], only this series is required.

Also, I want to make sure that what you tried in that branch is fixing
the NULL pointer dereference on spi_pxa2xx_platform module removal when
touch input crashed, not fixing the touch input crashing itself?

[1] https://bugzilla.kernel.org/show_bug.cgi?id=206403
[2] https://bugzilla.kernel.org/show_bug.cgi?id=206403#c1

Thanks,

Tsuchiya Yuto