spi: uniphier: fix reference count leak in uniphier_spi_probe()

commit 37c2c83 upstream.

The issue happens in several error paths in uniphier_spi_probe().
When either dma_get_slave_caps() or devm_spi_register_master() returns
an error code, the function forgets to decrease the refcount of both
`dma_rx` and `dma_tx` objects, which may lead to refcount leaks.

Fix it by decrementing the reference count of specific objects in
those error paths.

Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Reviewed-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Fixes: 28d1ddd ("spi: uniphier: Add DMA transfer mode support")
Link: https://lore.kernel.org/r/20220125101214.35677-1-xiongx18@fudan.edu.cn
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/spi/spi-uniphier.c

@@ -726,7 +726,7 @@ static int uniphier_spi_probe(struct platform_device *pdev)
 		if (ret) {
 			dev_err(&pdev->dev, "failed to get TX DMA capacities: %d\n",
 				ret);
-			goto out_disable_clk;
+			goto out_release_dma;
 		}
 		dma_tx_burst = caps.max_burst;
 	}
@@ -735,7 +735,7 @@ static int uniphier_spi_probe(struct platform_device *pdev)
 	if (IS_ERR_OR_NULL(master->dma_rx)) {
 		if (PTR_ERR(master->dma_rx) == -EPROBE_DEFER) {
 			ret = -EPROBE_DEFER;
-			goto out_disable_clk;
+			goto out_release_dma;
 		}
 		master->dma_rx = NULL;
 		dma_rx_burst = INT_MAX;
@@ -744,7 +744,7 @@ static int uniphier_spi_probe(struct platform_device *pdev)
 		if (ret) {
 			dev_err(&pdev->dev, "failed to get RX DMA capacities: %d\n",
 				ret);
-			goto out_disable_clk;
+			goto out_release_dma;
 		}
 		dma_rx_burst = caps.max_burst;
 	}
@@ -753,10 +753,20 @@ static int uniphier_spi_probe(struct platform_device *pdev)
 
 	ret = devm_spi_register_master(&pdev->dev, master);
 	if (ret)
-		goto out_disable_clk;
+		goto out_release_dma;
 
 	return 0;
 
+out_release_dma:
+	if (!IS_ERR_OR_NULL(master->dma_rx)) {
+		dma_release_channel(master->dma_rx);
+		master->dma_rx = NULL;
+	}
+	if (!IS_ERR_OR_NULL(master->dma_tx)) {
+		dma_release_channel(master->dma_tx);
+		master->dma_tx = NULL;
+	}
+
 out_disable_clk:
 	clk_disable_unprepare(priv->clk);