mlx5: handle DMA mapping error case for XDP redirect

Commit 58b99ee3 ("net/mlx5e: Add support for XDP_REDIRECT in device-out side")
forgot to return/free the xdp_frame in case the DMA mapping failed, correct this.

Also DMA unmap the frame in case mlx5e_xmit_xdp_frame() fails.

Fixes: 58b99ee3 ("net/mlx5e: Add support for XDP_REDIRECT in device-out side")
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c

@@ -283,6 +283,7 @@ int mlx5e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
 		xdpi.dma_addr = dma_map_single(sq->pdev, xdpf->data, xdpf->len,
 					       DMA_TO_DEVICE);
 		if (unlikely(dma_mapping_error(sq->pdev, xdpi.dma_addr))) {
+			xdp_return_frame_rx_napi(xdpf);
 			drops++;
 			continue;
 		}
@@ -290,6 +291,8 @@ int mlx5e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
 		xdpi.xdpf = xdpf;
 
 		if (unlikely(!mlx5e_xmit_xdp_frame(sq, &xdpi))) {
+			dma_unmap_single(sq->pdev, xdpi.dma_addr,
+					 xdpf->len, DMA_TO_DEVICE);
 			xdp_return_frame_rx_napi(xdpf);
 			drops++;
 		}