[Intel-gfx] [PATCH] drm/i915/mst: Make sure all resources are freed for MST topology manager before destroy

[Stanislav Lisovskiy]

In some of the CI failures we have see a race condition, when we were getting
continuous hpd pulses, forcing DP MST topology manager to try handling them,
however if this is combined with module reload that might cause it
to try destroying the already locked mutex, also some workqueue might attempt
to use already freed encoder resources, because
drm_dp_mst_topology_mgr_destroy doesn't check if mutex is still locked(triggers
WARN) and flushes only one drm_dp_mst_link_probe_work queue, while others, like
drm_dp_mst_up_req_work might be running at the moment, especially in case if
due to some other sw/hw bug, we are constantly getting hpd pulses from MST device.
Best way would be to modify drm_dp_mst_topology_mgr_destroy function itself, however
as it might take way more time, for now lets try to call drm_dp_mst_topology_mgr_suspend
first, which seems to do all the required actions.

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp_mst.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 3ba4a2fef98a..9c587b40cf42 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -1298,6 +1298,7 @@ intel_dp_mst_encoder_cleanup(struct intel_digital_port *dig_port)
 	if (!intel_dp_mst_source_support(intel_dp))
 		return;
 
+	drm_dp_mst_topology_mgr_suspend(&intel_dp->mst_mgr);
 	drm_dp_mst_topology_mgr_destroy(&intel_dp->mst_mgr);
 	/* encoders will get killed by normal cleanup */
 
-- 
2.37.3