nouveau crash due to missing channel (WAS: Re: [ANNOUNCE] 3.12.12-rt19)

[Sebastian Andrzej Siewior]

* Maarten Lankhorst | 2014-03-07 12:36:13 [+0100]:

>>I can't find any kind of locking so my question is what ensures that chan is
>>not set to NULL between nouveau_fence_done() and
>>nouveau_fence_wait_uevent()? There are just a few opcodes in between but
>>nothing that pauses nouveau_fence_signal().
>Absolutely nothing. :-) Worse still, there's no guarantee that channel isn't freed, but hopefully that is less likely to be an issue.

Okay, so I hit the correct spot. What do we do here? Do you want the
patch I posted without the WARN_ON() or do you prefer to fix this in an
other way?

>~Maarten

Sebastian