hwrng: exynos - Fix unbalanced PM runtime put on timeout error path

commit f1925d78d7b710a1179828d53e918295f5f5d222 upstream.

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")
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/hw_random/exynos-rng.c b/drivers/char/hw_random/exynos-rng.c
index 30cf4623184fbdc39387d5448cd5b4e281754053..aa30af5f0f2bf95288f6a2735b9b5e672f86fde0 100644 (file)
--- a/drivers/char/hw_random/exynos-rng.c
+++ b/drivers/char/hw_random/exynos-rng.c
@@ -89,6 +89,7 @@ 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);
 
@@ -97,17 +98,20 @@ 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)