[PATCH 2/3] drm/amd/display: Destroy FRL status polling workqueue in amdgpu_dm_fini()

[Eren Özen via B4 Relay]

From: Eren Özen <erenozen@xxxxxxxxxxxxxx>

amdgpu_dm_init() allocates hdmi_frl_status_polling_wq on every device
with at least one display link, but amdgpu_dm_fini() never destroys it,
unlike the other display manager workqueues. Every unbind or unload of
amdgpu leaks the workqueue and its rescuer thread, and each rebind adds
another one, visible as an extra kworker/R-hdmi_frl_status_polling_wq
thread.

The polling work also re-queues itself every 200ms while an HDMI FRL
stream is active and dereferences dm->dc under dm->dc_lock. Nothing on
the teardown path cancels it, so if it is still pending when
amdgpu_dm_fini() runs, it can run after dc_destroy() and
mutex_destroy(&dm->dc_lock).

Cancel the polling work and destroy its workqueue at the start of
amdgpu_dm_fini(), next to the vblank control workqueue. With the
previous patch, the work item is initialized before the workqueue is
allocated, so checking the workqueue pointer is enough to know that
both are valid, including on the amdgpu_dm_init() error path. This
patch depends on that ordering.

Fixes: 5c9b8b27a883 ("drm/amd/display: Tie FRL support into amdgpu_dm")
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Eren Özen <erenozen@xxxxxxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index bf2f74d7d9..fed1893d2f 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -889,6 +889,12 @@ static void amdgpu_dm_fini(struct amdgpu_device *adev)
 		adev->dm.vblank_control_workqueue = NULL;
 	}
 
+	if (adev->dm.hdmi_frl_status_polling_wq) {
+		cancel_delayed_work_sync(&adev->dm.hdmi_frl_status_polling_work);
+		destroy_workqueue(adev->dm.hdmi_frl_status_polling_wq);
+		adev->dm.hdmi_frl_status_polling_wq = NULL;
+	}
+
 	if (adev->dm.idle_workqueue) {
 		if (adev->dm.idle_workqueue->running) {
 			adev->dm.idle_workqueue->enable = false;

-- 
2.56.0