linux-kernel - [PATCH v3] dmaengine: fsl-edma: disable clks on all error paths

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Date:   Thu, 14 Dec 2017 12:50:51 +0100
From:   Andreas Platschek <andreas.platschek@...ntech.at>
To:     vinod.koul@...el.com
Cc:     dan.j.williams@...el.com, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org, sil2review@...ts.osadl.org,
        Andreas Platschek <andreas.platschek@...ntech.at>
Subject: [PATCH v3] dmaengine: fsl-edma: disable clks on all error paths

Previously enabled clks are only disabled if clk_prepare_enable() fails.
However, there are other error paths were the previously enabled
clocks are not disabled.

To fix the problem, fsl_disable_clocks() now takes the number of clocks
that shall be disabled + unprepared. For existing calls were all clocks
were already successfully prepared + enabled, DMAMUX_NR is passed to
disable + unprepare all clocks.

In error paths were only some clocks were successfully prepared +
enabled the loop counter is passed, in order to disable + unprepare
all successfully prepared + enabled clocks.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Andreas Platschek <andreas.platschek@...ntech.at>
---
V2->V3: in V2 i added the clk_disable_unprepare() directly into the
error paths. Vinod Koul then suggested to modify fsl_disable_clocks() and
consistently invoke that to disable + unprepare clocks.

 drivers/dma/fsl-edma.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/dma/fsl-edma.c b/drivers/dma/fsl-edma.c
index 6775f2c74e25..c7568869284e 100644
--- a/drivers/dma/fsl-edma.c
+++ b/drivers/dma/fsl-edma.c
@@ -863,11 +863,11 @@ static void fsl_edma_irq_exit(
 	}
 }
 
-static void fsl_disable_clocks(struct fsl_edma_engine *fsl_edma)
+static void fsl_disable_clocks(struct fsl_edma_engine *fsl_edma, int nr_clocks)
 {
 	int i;
 
-	for (i = 0; i < DMAMUX_NR; i++)
+	for (i = 0; i < nr_clocks; i++)
 		clk_disable_unprepare(fsl_edma->muxclk[i]);
 }
 
@@ -904,25 +904,25 @@ static int fsl_edma_probe(struct platform_device *pdev)
 
 		res = platform_get_resource(pdev, IORESOURCE_MEM, 1 + i);
 		fsl_edma->muxbase[i] = devm_ioremap_resource(&pdev->dev, res);
-		if (IS_ERR(fsl_edma->muxbase[i]))
+		if (IS_ERR(fsl_edma->muxbase[i])) {
+			/* on error: disable all previously enabled clks */
+			fsl_disable_clocks(fsl_edma, i);
 			return PTR_ERR(fsl_edma->muxbase[i]);
+		}
 
 		sprintf(clkname, "dmamux%d", i);
 		fsl_edma->muxclk[i] = devm_clk_get(&pdev->dev, clkname);
 		if (IS_ERR(fsl_edma->muxclk[i])) {
 			dev_err(&pdev->dev, "Missing DMAMUX block clock.\n");
+			/* on error: disable all previously enabled clks */
+			fsl_disable_clocks(fsl_edma, i);
 			return PTR_ERR(fsl_edma->muxclk[i]);
 		}
 
 		ret = clk_prepare_enable(fsl_edma->muxclk[i]);
-		if (ret) {
-			/* disable only clks which were enabled on error */
-			for (; i >= 0; i--)
-				clk_disable_unprepare(fsl_edma->muxclk[i]);
-
-			dev_err(&pdev->dev, "DMAMUX clk block failed.\n");
-			return ret;
-		}
+		if (ret)
+			/* on error: disable all previously enabled clks */
+			fsl_disable_clocks(fsl_edma, i);
 
 	}
 
@@ -976,7 +976,7 @@ static int fsl_edma_probe(struct platform_device *pdev)
 	if (ret) {
 		dev_err(&pdev->dev,
 			"Can't register Freescale eDMA engine. (%d)\n", ret);
-		fsl_disable_clocks(fsl_edma);
+		fsl_disable_clocks(fsl_edma, DMAMUX_NR);
 		return ret;
 	}
 
@@ -985,7 +985,7 @@ static int fsl_edma_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev,
 			"Can't register Freescale eDMA of_dma. (%d)\n", ret);
 		dma_async_device_unregister(&fsl_edma->dma_dev);
-		fsl_disable_clocks(fsl_edma);
+		fsl_disable_clocks(fsl_edma, DMAMUX_NR);
 		return ret;
 	}
 
@@ -1015,7 +1015,7 @@ static int fsl_edma_remove(struct platform_device *pdev)
 	fsl_edma_cleanup_vchan(&fsl_edma->dma_dev);
 	of_dma_controller_free(np);
 	dma_async_device_unregister(&fsl_edma->dma_dev);
-	fsl_disable_clocks(fsl_edma);
+	fsl_disable_clocks(fsl_edma, DMAMUX_NR);
 
 	return 0;
 }
-- 
2.11.0