[Intel-gfx] [PATCH] drm/i915/gt: Wait for RCUs frees before asserting idle on unload

[Chris Wilson]

During driver unload, we have many asserts that we have released our
bookkeeping structs and are idle. In some cases, these struct are
protected by RCU and we do not release them until after an RCU grace
period.

Reported-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Fixes: 130a95e9098e ("drm/i915/gem: Consolidate ctx->engines[] release")
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
---
 drivers/gpu/drm/i915/gt/intel_gt.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/intel_gt.c
index 3dea8881e915..d09f7596cb98 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt.c
@@ -667,6 +667,9 @@ void intel_gt_driver_release(struct intel_gt *gt)
 
 void intel_gt_driver_late_release(struct intel_gt *gt)
 {
+	/* We need to wait for inflight RCU frees to release their grip */
+	rcu_barrier();
+
 	intel_uc_driver_late_release(&gt->uc);
 	intel_gt_fini_requests(gt);
 	intel_gt_fini_reset(gt);
-- 
2.20.1