releases/4.4.13/hwrng-exynos-fix-unbalanced-pm-runtime-put-on-timeout-error-path.patch

   1 From f1925d78d7b710a1179828d53e918295f5f5d222 Mon Sep 17 00:00:00 2001
   2 From: Krzysztof Kozlowski <k.kozlowski@samsung.com>
   3 Date: Mon, 14 Mar 2016 09:07:13 +0900
   4 Subject: hwrng: exynos - Fix unbalanced PM runtime put on timeout error path
   5
   6 From: Krzysztof Kozlowski <k.kozlowski@samsung.com>
   7
   8 commit f1925d78d7b710a1179828d53e918295f5f5d222 upstream.
   9
  10 In case of timeout during read operation, the exit path lacked PM
  11 runtime put. This could lead to unbalanced runtime PM usage counter thus
  12 leaving the device in an active state.
  13
  14 Fixes: d7fd6075a205 ("hwrng: exynos - Add timeout for waiting on init done")
  15 Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
  16 Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
  17 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  18
  19 ---
  20  drivers/char/hw_random/exynos-rng.c |   10 +++++++---
  21  1 file changed, 7 insertions(+), 3 deletions(-)
  22
  23 --- a/drivers/char/hw_random/exynos-rng.c
  24 +++ b/drivers/char/hw_random/exynos-rng.c
  25 @@ -89,6 +89,7 @@ static int exynos_read(struct hwrng *rng
  26                                                 struct exynos_rng, rng);
  27         u32 *data = buf;
  28         int retry = 100;
  29 +       int ret = 4;
  30
  31         pm_runtime_get_sync(exynos_rng->dev);
  32
  33 @@ -97,17 +98,20 @@ static int exynos_read(struct hwrng *rng
  34         while (!(exynos_rng_readl(exynos_rng,
  35                         EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE) && --retry)
  36                 cpu_relax();
  37 -       if (!retry)
  38 -               return -ETIMEDOUT;
  39 +       if (!retry) {
  40 +               ret = -ETIMEDOUT;
  41 +               goto out;
  42 +       }
  43
  44         exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET);
  45
  46         *data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET);
  47
  48 +out:
  49         pm_runtime_mark_last_busy(exynos_rng->dev);
  50         pm_runtime_put_sync_autosuspend(exynos_rng->dev);
  51
  52 -       return 4;
  53 +       return ret;
  54  }
  55
  56  static int exynos_rng_probe(struct platform_device *pdev)