[PATCH] mmc: sdhci-of-dwcmshc: check bus clock enable result in the, probe() method

[PATCH] mmc: sdhci-of-dwcmshc: check bus clock enable result in the, probe() method

[Sergey Shtylyov]

In the driver's probe() method, clk_disable_unprepare() for the bus clock
is called on the error path even if the prior clk_prepare_enable() call has
failed -- that causes the prepare/enable counter imbalance.  Also, the same
kind of problem can happen in the driver's suspend() method; note that the
resume() method does check for the clk_prepare_enable()'s success -- let's
just be consistent and do that in probe() method too (BTW, I don't know for
sure what does the bus clock control -- if it affects the register access,
the driver is likely to cause a kernel oops iff it fails to prepare/enable
the bus clock in the probe() method)...

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

Fixes: e438cf49b305 ("mmc: sdhci-of-dwcmshc: add SDHCI OF Synopsys DWC MSHC driver")
Fixes: bccce2ec7790 ("mmc: sdhci-of-dwcmshc: add suspend/resume support")
Signed-off-by: Sergey Shtylyov <s.shtylyov@auroraos.dev>

---
This patch is against the fixes branch of Ulf Hansson's mmc.git repo...

 drivers/mmc/host/sdhci-of-dwcmshc.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
index 0b2158a7e409..83af8d2048d7 100644
--- a/drivers/mmc/host/sdhci-of-dwcmshc.c
+++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
@@ -2441,13 +2441,16 @@ static int dwcmshc_probe(struct platform_device *pdev)
 			return err;
 
 		priv->bus_clk = devm_clk_get(dev, "bus");
-		if (!IS_ERR(priv->bus_clk))
-			clk_prepare_enable(priv->bus_clk);
+		if (!IS_ERR(priv->bus_clk)) {
+			err = clk_prepare_enable(priv->bus_clk);
+			if (err)
+				goto err_clk;
+		}
 	}
 
 	err = mmc_of_parse(host->mmc);
 	if (err)
-		goto err_clk;
+		goto err_bus_clk;
 
 	sdhci_get_of_property(pdev);
 
@@ -2461,7 +2464,7 @@ static int dwcmshc_probe(struct platform_device *pdev)
 	if (pltfm_data->init) {
 		err = pltfm_data->init(&pdev->dev, host, priv);
 		if (err)
-			goto err_clk;
+			goto err_bus_clk;
 	}
 
 #ifdef CONFIG_ACPI
@@ -2507,9 +2510,10 @@ static int dwcmshc_probe(struct platform_device *pdev)
 err_rpm:
 	pm_runtime_disable(dev);
 	pm_runtime_put_noidle(dev);
+err_bus_clk:
+	clk_disable_unprepare(priv->bus_clk);
 err_clk:
 	clk_disable_unprepare(pltfm_host->clk);
-	clk_disable_unprepare(priv->bus_clk);
 	clk_bulk_disable_unprepare(priv->num_other_clks, priv->other_clks);
 	return err;
 }
-- 
2.54.0

Re: [PATCH] mmc: sdhci-of-dwcmshc: check bus clock enable result in the, probe() method

[Sergey Shtylyov]

On 5/28/26 11:42 PM, Sergey Shtylyov wrote:

> In the driver's probe() method, clk_disable_unprepare() for the bus clock
> is called on the error path even if the prior clk_prepare_enable() call has
> failed -- that causes the prepare/enable counter imbalance.  Also, the same

   I missed the fact that the remove() would be affected by the imbalance as well.
I'll update the description and repost...

> kind of problem can happen in the driver's suspend() method; note that the
> resume() method does check for the clk_prepare_enable()'s success -- let's
> just be consistent and do that in probe() method too (BTW, I don't know for
> sure what does the bus clock control -- if it affects the register access,
> the driver is likely to cause a kernel oops iff it fails to prepare/enable
> the bus clock in the probe() method)...
> 
> Found by Linux Verification Center (linuxtesting.org) with the Svace static
> analysis tool.
> 
> Fixes: e438cf49b305 ("mmc: sdhci-of-dwcmshc: add SDHCI OF Synopsys DWC MSHC driver")
> Fixes: bccce2ec7790 ("mmc: sdhci-of-dwcmshc: add suspend/resume support")
> Signed-off-by: Sergey Shtylyov <s.shtylyov@auroraos.dev>
[...]

MBR, Sergey