Re: [PATCH v2 01/16] watchdog: refactor watchdog_init_timeout

Guenter Roeck
2019-04-16T13:23:13Z

On 4/16/19 3:25 AM, Wolfram Sang wrote:
> The function is not easy to read and has a problem: -EINVAL is returned
> when the module parameter is invalid but the DT parameter is OK.
>
> Refactor the code to have the same pattern of checks for the module
> parameter and DT. Further ones can be easily added in the future if the
> need arises. The above mentioned problem is fixed, too.
>
> Some documentation is added to describe the different handlings of '0'
> for the module parameter and the DT property.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

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

> ---
> drivers/watchdog/watchdog_core.c | 33 +++++++++++++++++++--------------
> 1 file changed, 19 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
> index eb8fa25f8eb2..21e53cc49977 100644
> --- a/drivers/watchdog/watchdog_core.c
> +++ b/drivers/watchdog/watchdog_core.c
> @@ -105,9 +105,12 @@ static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
> * timeout module parameter (if it is valid value) or the timeout-sec property
> * (only if it is a valid value and the timeout_parm is out of bounds).
> * If none of them are valid then we keep the old value (which should normally
> - * be the default timeout value).
> + * be the default timeout value). Note that for the module parameter, '0' means
> + * 'use default' while it is an invalid value for the timeout-sec property.
> + * It should simply be dropped if you want to use the default value then.
> *
> - * A zero is returned on success and -EINVAL for failure.
> + * A zero is returned on success or -EINVAL if all provided values are out of
> + * bounds.
> */
> int watchdog_init_timeout(struct watchdog_device *wdd,
> unsigned int timeout_parm, struct device *dev)
> @@ -117,22 +120,24 @@ int watchdog_init_timeout(struct watchdog_device *wdd,
>
> watchdog_check_min_max_timeout(wdd);
>
> - /* try to get the timeout module parameter first */
> - if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
> - wdd->timeout = timeout_parm;
> - return ret;
> - }
> - if (timeout_parm)
> + /* check the driver supplied value (likely a module parameter) first */
> + if (timeout_parm) {
> + if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
> + wdd->timeout = timeout_parm;
> + return 0;
> + }
> ret = -EINVAL;
> + }
>
> /* try to get the timeout_sec property */
> - if (dev == NULL || dev->of_node == NULL)
> - return ret;
> - of_property_read_u32(dev->of_node, "timeout-sec", &t);
> - if (!watchdog_timeout_invalid(wdd, t) && t)
> - wdd->timeout = t;
> - else
> + if (dev && dev->of_node &&
> + of_property_read_u32(dev->of_node, "timeout-sec", &t) == 0) {
> + if (t && !watchdog_timeout_invalid(wdd, t)) {
> + wdd->timeout = t;
> + return 0;
> + }
> ret = -EINVAL;
> + }
>
> return ret;
> }
>