From 9232c80659e941ffa6c7bfc96bd64c6172ef0452 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Sun, 23 Feb 2020 11:49:39 +0000 Subject: [PATCH] watchdog: Add stop_on_reboot parameter to control reboot policy Many watchdog drivers use watchdog_stop_on_reboot() helper in order to stop the watchdog on system reboot. Unfortunately, this logic is coded in driver's probe function and doesn't allows user to decide what to do during shutdown/reboot. On the other side, Xen and Qemu watchdog drivers (xen_wdt and i6300esb) may be configured to either send NMI or turn off/reboot VM as the watchdog action. As the kernel may stuck at any state, sending NMIs can't reliably reboot the VM. At Arista, we benefited from the following set-up: the emulated watchdogs trigger VM reset and softdog is set to catch less severe conditions to generate vmcore. Just before reboot watchdog's timeout is increased to some good-enough value (3 mins). That keeps watchdog always running and guarantees that VM doesn't stuck. Provide new stop_on_reboot module parameter to let user control watchdog's reboot policy. Cc: Guenter Roeck Cc: Wim Van Sebroeck Cc: linux-watchdog@vger.kernel.org Signed-off-by: Dmitry Safonov Reviewed-by: Guenter Roeck Link: https://lore.kernel.org/r/20200223114939.194754-1-dima@arista.com Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck --- drivers/watchdog/watchdog_core.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c index 861daf4f37b2..423844757812 100644 --- a/drivers/watchdog/watchdog_core.c +++ b/drivers/watchdog/watchdog_core.c @@ -39,6 +39,10 @@ static DEFINE_IDA(watchdog_ida); +static int stop_on_reboot = -1; +module_param(stop_on_reboot, int, 0444); +MODULE_PARM_DESC(stop_on_reboot, "Stop watchdogs on reboot (0=keep watching, 1=stop)"); + /* * Deferred Registration infrastructure. * @@ -254,6 +258,14 @@ static int __watchdog_register_device(struct watchdog_device *wdd) } } + /* Module parameter to force watchdog policy on reboot. */ + if (stop_on_reboot != -1) { + if (stop_on_reboot) + set_bit(WDOG_STOP_ON_REBOOT, &wdd->status); + else + clear_bit(WDOG_STOP_ON_REBOOT, &wdd->status); + } + if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) { wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;