mmc: mmc_spi: add checks for dma mapping error

There is no checks for dma mapping errors in mmc_spi.
Tha patch fixes that and by the way it adds dma_unmap_single(ones_dma)
that was left on a failure path mmc_spi_probe().

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/mmc_spi.c

@@ -925,6 +925,10 @@ mmc_spi_data_do(struct mmc_spi_host *host, struct mmc_command *cmd,
 
 			dma_addr = dma_map_page(dma_dev, sg_page(sg), 0,
 						PAGE_SIZE, dir);
+			if (dma_mapping_error(dma_dev, dma_addr)) {
+				data->error = -EFAULT;
+				break;
+			}
 			if (direction == DMA_TO_DEVICE)
 				t->tx_dma = dma_addr + sg->offset;
 			else
@@ -1393,10 +1397,12 @@ static int mmc_spi_probe(struct spi_device *spi)
 		host->dma_dev = dev;
 		host->ones_dma = dma_map_single(dev, ones,
 				MMC_SPI_BLOCKSIZE, DMA_TO_DEVICE);
+		if (dma_mapping_error(dev, host->ones_dma))
+			goto fail_ones_dma;
 		host->data_dma = dma_map_single(dev, host->data,
 				sizeof(*host->data), DMA_BIDIRECTIONAL);
-
-		/* REVISIT in theory those map operations can fail... */
+		if (dma_mapping_error(dev, host->data_dma))
+			goto fail_data_dma;
 
 		dma_sync_single_for_cpu(host->dma_dev,
 				host->data_dma, sizeof(*host->data),
@@ -1462,6 +1468,11 @@ static int mmc_spi_probe(struct spi_device *spi)
 	if (host->dma_dev)
 		dma_unmap_single(host->dma_dev, host->data_dma,
 				sizeof(*host->data), DMA_BIDIRECTIONAL);
+fail_data_dma:
+	if (host->dma_dev)
+		dma_unmap_single(host->dma_dev, host->ones_dma,
+				MMC_SPI_BLOCKSIZE, DMA_TO_DEVICE);
+fail_ones_dma:
 	kfree(host->data);
 
 fail_nobuf1: