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 and a Wandboard. v6 tweaks the wording in watchdog-parameters.txt to avoid having to update it if and when the watchdog core grows new parameters. It also adds a little more rationale to the commit messages for 2/3 and 3/3, and adds Reviewed-bys to 1/3 which is unchanged from v5. v5 is identical to v4 posted in January, just rebased to current master (v4.12-rc2). v4 is mostly identical to v1. The differences are that the ability to compile out this feature is removed, and the ability to set the default value for the watchdog.open_timeout command line parameter via Kconfig is split into a separate patch. Compared to v2/v3, this drops the ability to set the open_timeout via a device property; I'll leave implementing that to those who actually need it. Rasmus Villemoes (3): watchdog: introduce watchdog_worker_should_ping helper watchdog: introduce watchdog.open_timeout commandline parameter watchdog: introduce CONFIG_WATCHDOG_OPEN_TIMEOUT Documentation/watchdog/watchdog-parameters.txt | 9 +++++++ drivers/watchdog/Kconfig | 9 +++++++ drivers/watchdog/watchdog_dev.c | 37 +++++++++++++++++++++++--- 3 files changed, 51 insertions(+), 4 deletions(-) -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
