[lvc-project] [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 (and the same thing happens in the remove() method as well) -- that
would cause the prepare/enable counter imbalance.  Also, the same problem
can happen in the driver's suspend() method; note that the resume() method
does check the clk_prepare_enable()'s result -- let's be consistent and do
that in probe() method as well.  BTW, I don't know for sure what does the
bus clock control -- if it affects the register accesses, the driver will
likely cause (e.g. on ARM) a kernel oops if 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 at auroraos.dev>
Acked-by: Adrian Hunter <adrian.hunter at intel.com>

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

I decided to also send it to the lvc-project ML because of the possibility
that a kernel oops is possible without it -- the corresponding checked was
marked as minor by me but it's quite possibly is not that minor...

 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 b9ecd91f44ad..29af07561a86 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