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Groups > linux.kernel > #1355672

[PATCH 3/5] hwrng: exynos - Fix unbalanced PM runtime put on timeout error path

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In case of timeout during read operation, the exit path lacked PM
runtime put. This could lead to unbalanced runtime PM usage counter thus
leaving the device in an active state.

Fixes: d7fd6075a205 ("hwrng: exynos - Add timeout for waiting on init done")
Cc: <stable@vger.kernel.org> # v4.4+
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
---
 drivers/char/hw_random/exynos-rng.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/char/hw_random/exynos-rng.c b/drivers/char/hw_random/exynos-rng.c
index d1fd21e99368..38b80f82ddd2 100644
--- a/drivers/char/hw_random/exynos-rng.c
+++ b/drivers/char/hw_random/exynos-rng.c
@@ -90,6 +90,7 @@ static int exynos_read(struct hwrng *rng, void *buf,
 						struct exynos_rng, rng);
 	u32 *data = buf;
 	int retry = 100;
+	int ret = 4;
 
 	pm_runtime_get_sync(exynos_rng->dev);
 
@@ -98,17 +99,20 @@ static int exynos_read(struct hwrng *rng, void *buf,
 	while (!(exynos_rng_readl(exynos_rng,
 			EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE) && --retry)
 		cpu_relax();
-	if (!retry)
-		return -ETIMEDOUT;
+	if (!retry) {
+		ret = -ETIMEDOUT;
+		goto out;
+	}
 
 	exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET);
 
 	*data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET);
 
+out:
 	pm_runtime_mark_last_busy(exynos_rng->dev);
 	pm_runtime_put_sync_autosuspend(exynos_rng->dev);
 
-	return 4;
+	return ret;
 }
 
 static int exynos_rng_probe(struct platform_device *pdev)
-- 
2.5.0

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[PATCH 1/5] hwrng: exynos - Hide PM functions with __maybe_unused Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2016-03-11 08:50 +0100
  [PATCH 5/5] hwrng: exynos - Disable runtime PM on driver unbind Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2016-03-11 09:00 +0100
    Re: [PATCH 5/5] hwrng: exynos - Disable runtime PM on driver unbind Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2016-03-12 06:30 +0100
  [PATCH 4/5] hwrng: exynos - Disable runtime PM on probe failure Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2016-03-11 09:00 +0100
  [PATCH 3/5] hwrng: exynos - Fix unbalanced PM runtime put on timeout  error path Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2016-03-11 09:00 +0100
  [PATCH 2/5] hwrng: exynos - Runtime suspend device after init Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2016-03-11 09:00 +0100
  Re: [PATCH 1/5] hwrng: exynos - Hide PM functions with __maybe_unused Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2016-03-12 06:00 +0100

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