[Intel-gfx] [PATCH] drm/i915/gem: Delay tracking the GEM context until it is registered

[Chris Wilson]

Quoting Mika Kuoppala (2020-07-24 12:55:39)
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > Quoting Chris Wilson (2020-07-23 19:33:48)
> >> Avoid exposing a partially constructed context by deferring the
> >> list_add() from the initial construction to the end of registration.
> >> Otherwise, if we peek into the list of contexts from inside debugfs, we
> >> may see the partially constructed context and change down some dangling
> >
> > s/change/chase/
> 
> that.
> 
> Are you sure about the fixes as it is not the commit that
> actually introduces the registration into context.list?
> 
> For me it looks like it is a4e7ccdac38e.

The one I picked was where we started adding more context setup after
the final step of list_add in __create_context(). More apropos would be
3aa9945a528e ("drm/i915: Separate GEM context construction and registration to userspace")
in the same kernel.

In the other direction, we have
f6e8aa387171 ("drm/i915: Report the number of closed vma held by each context in debugfs")
where we start using the contexts.list in debugfs.

In a4e7ccdac38e we are only moving the list_add(&ctx->link) around in
__create_context().
-Chris