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 30cf462..aa30af5 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)