On Fri, Jan 06, 2017 at 09:41:44AM +0100, Wolfram Sang wrote:
> It occured to me that the panic pretimeout governor will stall the
> softdog, because it is purely software which simply halts on panic.
> Testing governors with the softdog on the other hand is really useful.
> So, make this feature a compile time option which needs to be enabled
> explicitly. This also removes the overhead if pretimeout support is not
> used because it will now be compiled away (saving ~10% on ARM32).
>
> Signed-off-by: Wolfram Sang <wsa+rene...@sang-engineering.com>
> ---
> drivers/watchdog/Kconfig | 8 ++++++++
> drivers/watchdog/softdog.c | 27 +++++++++++++++++++--------
> 2 files changed, 27 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index acb00b53a5207b..70726ce3d166e8 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -71,6 +71,14 @@ config SOFT_WATCHDOG
> To compile this driver as a module, choose M here: the
> module will be called softdog.
>
> +config SOFT_WATCHDOG_PRETIMEOUT
> + bool "Software watchdog pretimeout governor support"
> + depends on SOFT_WATCHDOG && WATCHDOG_PRETIMEOUT_GOV
> + help
> + Enable this if you want to use pretimeout governors with the software
> + watchdog. Be aware that governors might affect the watchdog because it
> + is purely software, e.g. the panic governor will stall it!
> +
> config DA9052_WATCHDOG
> tristate "Dialog DA9052 Watchdog"
> depends on PMIC_DA9052
> diff --git a/drivers/watchdog/softdog.c b/drivers/watchdog/softdog.c
> index c7bdc986dca1c2..bc8b7da61d8aa7 100644
> --- a/drivers/watchdog/softdog.c
> +++ b/drivers/watchdog/softdog.c
> @@ -74,6 +74,7 @@ static struct timer_list softdog_ticktock =
>
> static struct watchdog_device softdog_dev;
>
> +#if IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)
> static void softdog_pretimeout(unsigned long data)
I would prefer __maybe_unused here ..
> {
> watchdog_notify_pretimeout(&softdog_dev);
> @@ -82,16 +83,23 @@ static void softdog_pretimeout(unsigned long data)
> static struct timer_list softdog_preticktock =
> TIMER_INITIALIZER(softdog_pretimeout, 0, 0);
>
> +static struct timer_list *softdog_preticktock_ptr = &softdog_preticktock;
> +#else
> +static void *softdog_preticktock_ptr = NULL;
> +#endif /* CONFIG_SOFT_WATCHDOG_PRETIMEOUT */
> +
> static int softdog_ping(struct watchdog_device *w)
> {
> if (!mod_timer(&softdog_ticktock, jiffies + (w->timeout * HZ)))
> __module_get(THIS_MODULE);
>
> - if (w->pretimeout)
> - mod_timer(&softdog_preticktock, jiffies +
> - (w->timeout - w->pretimeout) * HZ);
> - else
> - del_timer(&softdog_preticktock);
> + if (softdog_preticktock_ptr) {
and "if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT))" here.
> + if (w->pretimeout)
> + mod_timer(softdog_preticktock_ptr, jiffies +
> + (w->timeout - w->pretimeout) * HZ);
> + else
> + del_timer(softdog_preticktock_ptr);
> + }
>
> return 0;
> }
> @@ -101,15 +109,15 @@ static int softdog_stop(struct watchdog_device *w)
> if (del_timer(&softdog_ticktock))
> module_put(THIS_MODULE);
>
> - del_timer(&softdog_preticktock);
> + if (softdog_preticktock_ptr)
Is this conditional needed (assuming we get rid of softdog_preticktock_ptr) ?
Ok though if you want to use it to drop the code if not needed.
> + del_timer(softdog_preticktock_ptr);
>
> return 0;
> }
>
> static struct watchdog_info softdog_info = {
> .identity = "Software Watchdog",
> - .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE |
> - WDIOF_PRETIMEOUT,
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> };
>
> static const struct watchdog_ops softdog_ops = {
> @@ -134,6 +142,9 @@ static int __init softdog_init(void)
> watchdog_set_nowayout(&softdog_dev, nowayout);
> watchdog_stop_on_reboot(&softdog_dev);
>
> + if (softdog_preticktock_ptr)
> + softdog_info.options |= WDIOF_PRETIMEOUT;
> +
> ret = watchdog_register_device(&softdog_dev);
> if (ret)
> return ret;
> --
> 2.11.0
>
> --
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