[Intel-gfx] [PATCH] drm/i915/gt: Protect signaler walk with RCU

[Chris Wilson]

Quoting Matthew Auld (2020-02-19 19:02:36)
> > @@ -497,7 +497,7 @@ void i915_sched_node_fini(struct i915_sched_node *node)
> >                 GEM_BUG_ON(dep->signaler != node);
> >                 GEM_BUG_ON(!list_empty(&dep->dfs_link));
> >
> > -               list_del(&dep->signal_link);
> > +               list_del_rcu(&dep->signal_link);
> >                 if (dep->flags & I915_DEPENDENCY_ALLOC)
> >                         i915_dependency_free(dep);
> 
> Is this not a potential uaf? Do we not have to wait for the grace
> period before doing the free, or what?

If we insert SLAB_TYPESAFE_BY_RCU that should satisfy all.
(Give or that the amount of pain in thinking about rcu-freelists.)
-Chris