2017-12-14 11:51:46

by Andreas Platschek

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 <[email protected]>
---
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

2017-12-15 04:19:34

by Vinod Koul

Subject: Re: [PATCH v3] dmaengine: fsl-edma: disable clks on all error paths

On Thu, Dec 14, 2017 at 12:50:51PM +0100, Andreas Platschek wrote:
> 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.

Applied, thanks

--
~Vinod