If a watchdog driver tells the framework that the device is running, the framework takes care of feeding the watchdog until userspace opens the device. If the userspace application which is supposed to do that never comes up properly, the watchdog is fed indefinitely by the kernel. This can be especially problematic for embedded devices. These patches allow one to set a maximum time for which the kernel will feed the watchdog, thus ensuring that either userspace has come up, or the board gets reset. This allows fallback logic in the bootloader to attempt some recovery (for example, if an automatic update is in progress, it could roll back to the previous version). The patches have been tested on a Raspberry Pi 2 (with a suitably modified driver for setting WDOG_HW_RUNNING) and a Wandboard. Changes since the initial RFC (https://lkml.org/lkml/2016/7/14/254): take the timeout value from the device tree node rather than a watchdog module parameter. Rasmus Villemoes (2): watchdog: introduce watchdog_worker_should_ping helper watchdog: introduce CONFIG_WATCHDOG_OPEN_DEADLINE drivers/watchdog/Kconfig | 19 +++++++++++++++++++ drivers/watchdog/watchdog_core.c | 17 +++++++++++++++++ drivers/watchdog/watchdog_dev.c | 38 +++++++++++++++++++++++++++++++++++++- include/linux/watchdog.h | 9 +++++++++ 4 files changed, 82 insertions(+), 1 deletion(-) -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
