Can no longer shutdown after drm/radeon: Implement radeon_pci_shutdown

[Markus Trippelsdorf]

On 2013.12.12 at 03:27 +0000, Deucher, Alexander wrote:
> > On 2013.12.11 at 23:46 +0000, Deucher, Alexander wrote:
> > > > -----Original Message-----
> > > > From: Peter Chubb [mailto:peter.chubb at nicta.com.au]
> > > > Sent: Wednesday, December 11, 2013 5:11 PM
> > > > To: Markus Trippelsdorf
> > > > Cc: Peter Chubb; Deucher, Alexander; airlied at linux.ie; dri-
> > > > devel at lists.freedesktop.org
> > > > Subject: Re: Can no longer shutdown after drm/radeon: Implement
> > > > radeon_pci_shutdown
> > > >
> > > > >>>>> "Markus" == Markus Trippelsdorf <markus at trippelsdorf.de>
> > writes:
> > > >
> > > > Markus> On 2013.12.11 at 11:37 +1100, Peter Chubb wrote:
> > > >
> > > > Markus> It would be interesting to know where exactly it hangs.  Could
> > > > Markus> you comment out the *_fini(rdev) calls in
> > > > Markus> radeon_driver_unload_kms
> > > > (drivers/gpu/drm/radeon/radeon_kms.c)
> > > > Markus> one after the other to find out which one is responsible?
> > > >
> > > > It's radeon_device_fini() that is the problem.
> > >
> > > I think the problem is that the drm subsystem tears down the device
> > > via drm_driver.unload in drm_dev_unregister(), but now that we have a
> > > pci_driver.shutdown callback (which is needed for kexec) that gets
> > > called too so the driver gets torn down twice.
> > 
> > If that is the case the following patch should fix the issue.
> > Can you give it a try, Peter?
(Peter:)
> Thanks that works.  I tested shutdown, kexec, and s2disk --- all work
> correctly.

> That may work, but I think it's just papering over a race which may
> still bite someone else depending on the timing.

This leaves three possibilities:

1) Revert 846ae41ae99d now and come up with a solution with proper
locking for 3.14
2) Add my simple fix now and implement additional locking if the need
arises for 3.14.
3) Implement a fix with proper locking now.

It's your choice Alex.

-- 
Markus