linux-kernel - [PATCH] spi : spi-topcliff-pch: Fix to handle empty DMA buffers

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Message-Id: <20190313165541.22548-1-pakki001@umn.edu>
Date:   Wed, 13 Mar 2019 11:55:41 -0500
From:   Aditya Pakki <pakki001@....edu>
To:     pakki001@....edu
Cc:     kjlu@....edu, Mark Brown <broonie@...nel.org>,
        linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] spi : spi-topcliff-pch: Fix to handle empty DMA buffers

pch_alloc_dma_buf allocated tx, rx DMA buffers which can fail. Further,
these buffers are used without a check. The patch checks for these
failures and sends the error upstream.

Signed-off-by: Aditya Pakki <pakki001@....edu>
---
 drivers/spi/spi-topcliff-pch.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-topcliff-pch.c b/drivers/spi/spi-topcliff-pch.c
index fba3f180f233..8a5966963834 100644
--- a/drivers/spi/spi-topcliff-pch.c
+++ b/drivers/spi/spi-topcliff-pch.c
@@ -1299,18 +1299,27 @@ static void pch_free_dma_buf(struct pch_spi_board_data *board_dat,
 				  dma->rx_buf_virt, dma->rx_buf_dma);
 }
 
-static void pch_alloc_dma_buf(struct pch_spi_board_data *board_dat,
+static int pch_alloc_dma_buf(struct pch_spi_board_data *board_dat,
 			      struct pch_spi_data *data)
 {
 	struct pch_spi_dma_ctrl *dma;
+	int ret;
 
 	dma = &data->dma;
+	ret = 0;
 	/* Get Consistent memory for Tx DMA */
 	dma->tx_buf_virt = dma_alloc_coherent(&board_dat->pdev->dev,
 				PCH_BUF_SIZE, &dma->tx_buf_dma, GFP_KERNEL);
+	if (!dma->tx_buf_virt)
+		ret = -ENOMEM;
+
 	/* Get Consistent memory for Rx DMA */
 	dma->rx_buf_virt = dma_alloc_coherent(&board_dat->pdev->dev,
 				PCH_BUF_SIZE, &dma->rx_buf_dma, GFP_KERNEL);
+	if (!dma->rx_buf_virt)
+		ret = -ENOMEM;
+
+	return ret;
 }
 
 static int pch_spi_pd_probe(struct platform_device *plat_dev)
@@ -1387,7 +1396,9 @@ static int pch_spi_pd_probe(struct platform_device *plat_dev)
 
 	if (use_dma) {
 		dev_info(&plat_dev->dev, "Use DMA for data transfers\n");
-		pch_alloc_dma_buf(board_dat, data);
+		ret = pch_alloc_dma_buf(board_dat, data);
+		if (ret)
+			goto err_spi_register_master;
 	}
 
 	ret = spi_register_master(master);
-- 
2.17.1