Messages in this thread Patch in this message | | | Subject | Re: [PATCH] watchdog: core: add option to avoid early handling of watchdog | From | Guenter Roeck <> | Date | Thu, 11 May 2017 06:47:55 -0700 |
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On 05/11/2017 05:52 AM, Sebastian Reichel wrote: > On some systems its desirable to have watchdog reboot the system > when it does not come up fast enough. This adds a kernel parameter > to disable the auto-update of watchdog before userspace takes over > and a kernel option to set the default. The info messages were > added to shorten error searching on misconfigured systems. > > Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk> > --- > drivers/watchdog/Kconfig | 11 +++++++++++ > drivers/watchdog/watchdog_dev.c | 16 ++++++++++++++++ > 2 files changed, 27 insertions(+) > > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig > index 52a70ee6014f..4e08b2b97941 100644 > --- a/drivers/watchdog/Kconfig > +++ b/drivers/watchdog/Kconfig > @@ -46,6 +46,17 @@ config WATCHDOG_NOWAYOUT > get killed. If you say Y here, the watchdog cannot be stopped once > it has been started. > > +config WATCHDOG_HANDLE_BOOT_ENABLED > + bool "Disable watchdog shutdown on close"
Enable ?
> + default y > + help > + The default watchdog behaviour (which you get if you say Y here) is > + to ping watchdog devices, that were enabled before the driver has > + been loaded until control is taken over from userspace using the > + /dev/watchdog file. If you say N here, the kernel will not update > + the watchdog on its own. Thus if your userspace does not start fast > + enough your device will reboot. > + > config WATCHDOG_SYSFS > bool "Read different watchdog information through sysfs" > help > diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c > index d5d2bbd8f428..5e6d6d4db82f 100644 > --- a/drivers/watchdog/watchdog_dev.c > +++ b/drivers/watchdog/watchdog_dev.c > @@ -80,6 +80,9 @@ static struct watchdog_core_data *old_wd_data; > > static struct workqueue_struct *watchdog_wq; > > +static bool handle_boot_enabled = > + IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED); > + > static inline bool watchdog_need_worker(struct watchdog_device *wdd) > { > /* All variables in milli-seconds */ > @@ -956,6 +959,14 @@ static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno) > * and schedule an immediate ping. > */ > if (watchdog_hw_running(wdd)) { > + if (!handle_boot_enabled) { > + pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n", > + wdd->id); > + return 0;
I don't like the immediate return here; if some other code is added further below, it may miss this return. Something like
if (handle_boot_enabled) { // do everything here } else { // print message }
would be better.
> + } > + > + pr_info("auto-update boot-enabled watchdog%d until userspace takes over\n", > + wdd->id);
This message will add a lot of noise. If you really think it is useful please make it a debug message.
> __module_get(wdd->ops->owner); > kref_get(&wd_data->kref); > queue_delayed_work(watchdog_wq, &wd_data->work, 0); > @@ -1106,3 +1117,8 @@ void __exit watchdog_dev_exit(void) > class_unregister(&watchdog_class); > destroy_workqueue(watchdog_wq); > } > + > +module_param(handle_boot_enabled, bool, 0444); > +MODULE_PARM_DESC(handle_boot_enabled, > + "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default=" > + __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")"); >
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