linux-kernel - [PATCH] dma: uniphier-mdmac: fix call balance of mdev->clk handling routines

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Message-Id: <20250124110213.1285417-1-mordan@ispras.ru>
Date: Fri, 24 Jan 2025 14:02:13 +0300
From: Vitalii Mordan <mordan@...ras.ru>
To: Vinod Koul <vkoul@...nel.org>
Cc: Vitalii Mordan <mordan@...ras.ru>,
	Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Masahiro Yamada <yamada.masahiro@...ionext.com>,
	dmaengine@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org,
	Fedor Pchelkin <pchelkin@...ras.ru>,
	Alexey Khoroshilov <khoroshilov@...ras.ru>,
	Vadim Mutilin <mutilin@...ras.ru>
Subject: [PATCH] dma: uniphier-mdmac: fix call balance of mdev->clk handling routines

If the clock mdev->clk was enabled in uniphier_mdmac_probe(), it should be
disabled in any path. If dmaengine_terminate_sync() returns an error in
uniphier_mdmac_remove(), the clock mdev->clk will not be disabled.

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

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

Fixes: 32e74aabebc8 ("dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver")
Signed-off-by: Vitalii Mordan <mordan@...ras.ru>
---
 drivers/dma/uniphier-mdmac.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/dma/uniphier-mdmac.c b/drivers/dma/uniphier-mdmac.c
index 7a99f86ecb5a..471dc2ef4781 100644
--- a/drivers/dma/uniphier-mdmac.c
+++ b/drivers/dma/uniphier-mdmac.c
@@ -401,16 +401,12 @@ static int uniphier_mdmac_probe(struct platform_device *pdev)
 	if (IS_ERR(mdev->reg_base))
 		return PTR_ERR(mdev->reg_base);
 
-	mdev->clk = devm_clk_get(dev, NULL);
+	mdev->clk = devm_clk_get_enabled(dev, NULL);
 	if (IS_ERR(mdev->clk)) {
-		dev_err(dev, "failed to get clock\n");
+		dev_err(dev, "failed to get and enable clock\n");
 		return PTR_ERR(mdev->clk);
 	}
 
-	ret = clk_prepare_enable(mdev->clk);
-	if (ret)
-		return ret;
-
 	ddev = &mdev->ddev;
 	ddev->dev = dev;
 	dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
@@ -429,12 +425,12 @@ static int uniphier_mdmac_probe(struct platform_device *pdev)
 	for (i = 0; i < nr_chans; i++) {
 		ret = uniphier_mdmac_chan_init(pdev, mdev, i);
 		if (ret)
-			goto disable_clk;
+			return ret;
 	}
 
 	ret = dma_async_device_register(ddev);
 	if (ret)
-		goto disable_clk;
+		return ret;
 
 	ret = of_dma_controller_register(dev->of_node, of_dma_xlate_by_chan_id,
 					 ddev);
@@ -447,8 +443,6 @@ static int uniphier_mdmac_probe(struct platform_device *pdev)
 
 unregister_dmac:
 	dma_async_device_unregister(ddev);
-disable_clk:
-	clk_disable_unprepare(mdev->clk);
 
 	return ret;
 }
@@ -482,7 +476,6 @@ static void uniphier_mdmac_remove(struct platform_device *pdev)
 
 	of_dma_controller_free(pdev->dev.of_node);
 	dma_async_device_unregister(&mdev->ddev);
-	clk_disable_unprepare(mdev->clk);
 }
 
 static const struct of_device_id uniphier_mdmac_match[] = {
-- 
2.25.1