handle ttm_sg_tt_init() not being called before ttm_tt_fini()

Check that dmamap and segs are non-NULL as not all drivers call
ttm_sg_tt_init().

diff --git a/sys/dev/pci/drm/ttm/ttm_tt.c b/sys/dev/pci/drm/ttm/ttm_tt.c
index 3862519..21d1d9c 100644 (file)
--- a/sys/dev/pci/drm/ttm/ttm_tt.c
+++ b/sys/dev/pci/drm/ttm/ttm_tt.c
@@ -151,6 +151,9 @@ static void ttm_tt_init_fields(struct ttm_tt *ttm,
        ttm->swap_storage = NULL;
        ttm->sg = bo->sg;
        ttm->caching = caching;
+       ttm->dmat = bo->bdev->dmat;
+       ttm->map = NULL;
+       ttm->segs = NULL;
 }
 
 int ttm_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
@@ -184,9 +187,11 @@ void ttm_tt_fini(struct ttm_tt *ttm)
        ttm->dma_address = NULL;
        ttm->orders = NULL;
 
-       bus_dmamap_destroy(ttm->dmat, ttm->map);
-       km_free(ttm->segs, round_page(ttm->num_pages *
-           sizeof(bus_dma_segment_t)), &kv_any, &kp_zero);
+       if (ttm->map)
+               bus_dmamap_destroy(ttm->dmat, ttm->map);
+       if (ttm->segs)
+               km_free(ttm->segs, round_page(ttm->num_pages *
+                   sizeof(bus_dma_segment_t)), &kv_any, &kp_zero);
 }
 EXPORT_SYMBOL(ttm_tt_fini);
 
@@ -210,8 +215,6 @@ int ttm_sg_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
        ttm->segs = km_alloc(round_page(ttm->num_pages *
            sizeof(bus_dma_segment_t)), &kv_any, &kp_zero, &kd_waitok);
 
-       ttm->dmat = bo->bdev->dmat;
-
        if (bo->bdev->pool.use_dma32 == false)
                flags |= BUS_DMA_64BIT;
        if (bus_dmamap_create(ttm->dmat, ttm->num_pages << PAGE_SHIFT,