[PATCH v4 8/9] drm/amdgpu/userq: make sure queue is valid in the hang_detect_work

[Sunil Khatri <sunil.khatri@amd.com>]

Thread 1: Running amdgpu_userq_destroy which eventually remove
the queue from door bell and set userq_mgr = NULL.

Thread2: An interrupt might have scheduled the hang_detect_work
which still need userq_mgr to be valid but could get an NULL
ptrs.

To fix that make sure we cancel the hang_detect_work again before
setting userq_mgr to NULL.

Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
index 8b0b53f80499..5c2e0c400d5f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
@@ -427,7 +427,6 @@ static void amdgpu_userq_cleanup(struct amdgpu_usermode_queue *queue)
 	xa_erase_irq(&adev->userq_doorbell_xa, queue->doorbell_index);
 	amdgpu_userq_fence_driver_free(queue);
 	queue->fence_drv = NULL;
-	queue->userq_mgr = NULL;
 	list_del(&queue->userq_va_list);
 
 	up_read(&adev->reset_domain->sem);
@@ -635,6 +634,10 @@ amdgpu_userq_destroy(struct amdgpu_userq_mgr *uq_mgr, struct amdgpu_usermode_que
 	amdgpu_userq_cleanup(queue);
 	mutex_unlock(&uq_mgr->userq_mutex);
 
+	/* This is case an interrupt was fired and a hang detection work is pending */
+	cancel_delayed_work_sync(&queue->hang_detect_work);
+	queue->userq_mgr = NULL;
+
 	amdgpu_bo_reserve(queue->db_obj.obj, true);
 	amdgpu_bo_unpin(queue->db_obj.obj);
 	amdgpu_bo_unreserve(queue->db_obj.obj);
-- 
2.34.1