[PATCH v4 6/7] drm/amdgpu: Skip dma map resource for null RDMA device

[Philip Yang]

To test RDMA using dummy driver on the system without NIC/RDMA
device, the get/put dma pages pass in null device pointer, skip the
dma map/unmap resource and sg table to avoid null pointer access.

Signed-off-by: Philip Yang <Philip.Yang at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 33 +++++++++++---------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index 6c7133bf51d8..101a85263b53 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -698,12 +698,15 @@ int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
 		unsigned long size = min(cursor.size, MAX_SG_SEGMENT_SIZE);
 		dma_addr_t addr;
 
-		addr = dma_map_resource(dev, phys, size, dir,
-					DMA_ATTR_SKIP_CPU_SYNC);
-		r = dma_mapping_error(dev, addr);
-		if (r)
-			goto error_unmap;
-
+		if (dev) {
+			addr = dma_map_resource(dev, phys, size, dir,
+						DMA_ATTR_SKIP_CPU_SYNC);
+			r = dma_mapping_error(dev, addr);
+			if (r)
+				goto error_unmap;
+		} else {
+			addr = phys;
+		}
 		sg_set_page(sg, NULL, size, 0);
 		sg_dma_address(sg) = addr;
 		sg_dma_len(sg) = size;
@@ -717,10 +720,10 @@ int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
 	for_each_sgtable_sg((*sgt), sg, i) {
 		if (!sg->length)
 			continue;
-
-		dma_unmap_resource(dev, sg->dma_address,
-				   sg->length, dir,
-				   DMA_ATTR_SKIP_CPU_SYNC);
+		if (dev)
+			dma_unmap_resource(dev, sg->dma_address,
+					   sg->length, dir,
+					   DMA_ATTR_SKIP_CPU_SYNC);
 	}
 	sg_free_table(*sgt);
 
@@ -745,10 +748,12 @@ void amdgpu_vram_mgr_free_sgt(struct device *dev,
 	struct scatterlist *sg;
 	int i;
 
-	for_each_sgtable_sg(sgt, sg, i)
-		dma_unmap_resource(dev, sg->dma_address,
-				   sg->length, dir,
-				   DMA_ATTR_SKIP_CPU_SYNC);
+	if (dev) {
+		for_each_sgtable_sg(sgt, sg, i)
+			dma_unmap_resource(dev, sg->dma_address,
+					   sg->length, dir,
+					   DMA_ATTR_SKIP_CPU_SYNC);
+	}
 	sg_free_table(sgt);
 	kfree(sgt);
 }
-- 
2.43.2