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

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>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/char/hw_random/exynos-rng.c b/drivers/char/hw_random/exynos-rng.c
index d1fd21e9936810808c0051e185608f2d88cb51e7..38b80f82ddd2d90704ffb4feb53bcd0bbfd6bb33 100644 (file)
--- 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)