linux-kernel - [PATCH] dma: jz4780: fix call balance of jzdma->clk handling routines

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Message-Id: <20250120135059.302273-1-mordan@ispras.ru>
Date: Mon, 20 Jan 2025 16:50:59 +0300
From: Vitalii Mordan <mordan@...ras.ru>
To: Paul Cercueil <paul@...pouillou.net>
Cc: Vitalii Mordan <mordan@...ras.ru>,
	Vinod Koul <vkoul@...nel.org>,
	Alex Smith <alex.smith@...tec.com>,
	Zubair Lutfullah Kakakhel <Zubair.Kakakhel@...tec.com>,
	linux-mips@...r.kernel.org,
	dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Fedor Pchelkin <pchelkin@...ras.ru>,
	Alexey Khoroshilov <khoroshilov@...ras.ru>,
	Vadim Mutilin <mutilin@...ras.ru>,
	lvc-project@...uxtesting.org
Subject: [PATCH] dma: jz4780: fix call balance of jzdma->clk handling routines

If the clock jzdma->clk was not enabled in jz4780_dma_probe(), it should
not be disabled in any path.

Conversely, if it was enabled in jz4780_dma_probe(), it must be disabled
in all error paths to ensure proper cleanup.

Use the devm_clk_get_enabled() helper function to ensure proper call
balance for jzdma->clk.

Found by Linux Verification Center (linuxtesting.org) with Klever.

Fixes: d894fc6046fe ("dmaengine: jz4780: add driver for the Ingenic JZ4780 DMA controller")
Signed-off-by: Vitalii Mordan <mordan@...ras.ru>
---
 drivers/dma/dma-jz4780.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
index 100057603fd4..ff9c387fd8c1 100644
--- a/drivers/dma/dma-jz4780.c
+++ b/drivers/dma/dma-jz4780.c
@@ -896,15 +896,13 @@ static int jz4780_dma_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	jzdma->clk = devm_clk_get(dev, NULL);
+	jzdma->clk = devm_clk_get_enabled(dev, NULL);
 	if (IS_ERR(jzdma->clk)) {
-		dev_err(dev, "failed to get clock\n");
+		dev_err(dev, "failed to get and enable clock\n");
 		ret = PTR_ERR(jzdma->clk);
 		return ret;
 	}
 
-	clk_prepare_enable(jzdma->clk);
-
 	/* Property is optional, if it doesn't exist the value will remain 0. */
 	of_property_read_u32_index(dev->of_node, "ingenic,reserved-channels",
 				   0, &jzdma->chan_reserved);
@@ -972,7 +970,7 @@ static int jz4780_dma_probe(struct platform_device *pdev)
 
 	ret = platform_get_irq(pdev, 0);
 	if (ret < 0)
-		goto err_disable_clk;
+		return ret;
 
 	jzdma->irq = ret;
 
@@ -980,7 +978,7 @@ static int jz4780_dma_probe(struct platform_device *pdev)
 			  jzdma);
 	if (ret) {
 		dev_err(dev, "failed to request IRQ %u!\n", jzdma->irq);
-		goto err_disable_clk;
+		return ret;
 	}
 
 	ret = dmaenginem_async_device_register(dd);
@@ -1002,9 +1000,6 @@ static int jz4780_dma_probe(struct platform_device *pdev)
 
 err_free_irq:
 	free_irq(jzdma->irq, jzdma);
-
-err_disable_clk:
-	clk_disable_unprepare(jzdma->clk);
 	return ret;
 }
 
@@ -1015,7 +1010,6 @@ static void jz4780_dma_remove(struct platform_device *pdev)
 
 	of_dma_controller_free(pdev->dev.of_node);
 
-	clk_disable_unprepare(jzdma->clk);
 	free_irq(jzdma->irq, jzdma);
 
 	for (i = 0; i < jzdma->soc_data->nb_channels; i++)
-- 
2.25.1