drm/ttm: Reorder sys manager cleanup step

With the current cleanup flow, we could trigger a NULL pointer
dereference if there is a delayed destruction of a BO with a
system resource that gets executed on drain_workqueue() call,
as we attempt to free a resource using an already released
resource manager.

Remove the device from the device list and drain its workqueue
before releasing the system domain manager in ttm_device_fini().

Signed-off-by: Karolina Stolarek <karolina.stolarek@intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231016121525.2237838-1-karolina.stolarek@intel.com
Signed-off-by: Christian König <christian.koenig@amd.com>

diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
index 7726a72..d48b391 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_device.c
+++ b/drivers/gpu/drm/ttm/ttm_device.c
@@ -232,10 +232,6 @@ void ttm_device_fini(struct ttm_device *bdev)
        struct ttm_resource_manager *man;
        unsigned i;
 
-       man = ttm_manager_type(bdev, TTM_PL_SYSTEM);
-       ttm_resource_manager_set_used(man, false);
-       ttm_set_driver_manager(bdev, TTM_PL_SYSTEM, NULL);
-
        mutex_lock(&ttm_global_mutex);
        list_del(&bdev->device_list);
        mutex_unlock(&ttm_global_mutex);
@@ -243,6 +239,10 @@ void ttm_device_fini(struct ttm_device *bdev)
        drain_workqueue(bdev->wq);
        destroy_workqueue(bdev->wq);
 
+       man = ttm_manager_type(bdev, TTM_PL_SYSTEM);
+       ttm_resource_manager_set_used(man, false);
+       ttm_set_driver_manager(bdev, TTM_PL_SYSTEM, NULL);
+
        spin_lock(&bdev->lru_lock);
        for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i)
                if (list_empty(&man->lru[0]))