[Intel-gfx] [PATCH] drm/i915: Flush the i915_vm_release before ggtt shutdown

[Chris Wilson]

As the gen6_ppgtt may refer back to the GGTT for their page-directory
slots, make sure those __i915_vm_release are completed prior to shutting
down the GGTT.

Fixes: b32fa8111563 ("drm/i915/gtt: Defer address space cleanup to an RCU worker")
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
The workers are RCU deferred so need a barrier to first flush the frees
onto the workqueue.
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 4dd1fa956143..423c890d03bf 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2721,6 +2721,9 @@ static void ggtt_cleanup_hw(struct i915_ggtt *ggtt)
 
 	ggtt->vm.closed = true;
 
+	rcu_barrier(); /* flush the RCU'ed__i915_vm_release */
+	flush_workqueue(i915->wq);
+
 	mutex_lock(&i915->drm.struct_mutex);
 
 	list_for_each_entry_safe(vma, vn, &ggtt->vm.bound_list, vm_link)
-- 
2.22.0