Re: [PATCH v2] watchdog: tangox_wdt: test clock rate to avoid division by 0

[Guenter Roeck]

On 03/03/2016 12:24 AM, Wolfram Sang wrote:

From: Wolfram Sang <wsa+rene...@sang-engineering.com>

The clk API may return 0 on clk_get_rate, so we should check the result before
using it as a divisor. For this, refactor the code to use a central
error path.

Signed-off-by: Wolfram Sang <wsa+rene...@sang-engineering.com>

Reviewed-by: Guenter Roeck <li...@roeck-us.net>

---
  drivers/watchdog/tangox_wdt.c | 14 ++++++++++----
  1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/watchdog/tangox_wdt.c b/drivers/watchdog/tangox_wdt.c
index 709c1ed6fd79b9..cfbed7e051b619 100644
--- a/drivers/watchdog/tangox_wdt.c
+++ b/drivers/watchdog/tangox_wdt.c
@@ -139,6 +139,10 @@ static int tangox_wdt_probe(struct platform_device *pdev)
                return err;

        dev->clk_rate = clk_get_rate(dev->clk);
+       if (!dev->clk_rate) {
+               err = -EINVAL;
+               goto err;
+       }

        dev->wdt.parent = &pdev->dev;
        dev->wdt.info = &tangox_wdt_info;
@@ -171,10 +175,8 @@ static int tangox_wdt_probe(struct platform_device *pdev)
        }

        err = watchdog_register_device(&dev->wdt);
-       if (err) {
-               clk_disable_unprepare(dev->clk);
-               return err;
-       }
+       if (err)
+               goto err;

        platform_set_drvdata(pdev, dev);

@@ -187,6 +189,10 @@ static int tangox_wdt_probe(struct platform_device *pdev)
        dev_info(&pdev->dev, "SMP86xx/SMP87xx watchdog registered\n");

        return 0;
+
+ err:
+       clk_disable_unprepare(dev->clk);
+       return err;
  }

  static int tangox_wdt_remove(struct platform_device *pdev)