@@ -754,6 +754,16 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
}
if (val & WDIOS_ENABLECARD)
err = watchdog_start(wdd);
+
+ if (val & WDIOS_RUN_ON_REBOOT) {
+ if (val & WDIOS_STOP_ON_REBOOT) {
+ err = -EINVAL;
+ break;
+ }
+ watchdog_run_on_reboot(wdd);
+ } else if (val & WDIOS_STOP_ON_REBOOT) {
+ watchdog_stop_on_reboot(wdd);
+ }
break;
case WDIOC_KEEPALIVE:
if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
@@ -150,6 +150,12 @@ static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd)
set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
}
+/* Use the following function to keep the watchdog running on reboot */
+static inline void watchdog_run_on_reboot(struct watchdog_device *wdd)
+{
+ clear_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
+}
+
/* Use the following function to stop the watchdog when unregistering it */
static inline void watchdog_stop_on_unregister(struct watchdog_device *wdd)
{
@@ -53,6 +53,7 @@ struct watchdog_info {
#define WDIOS_DISABLECARD 0x0001 /* Turn off the watchdog timer */
#define WDIOS_ENABLECARD 0x0002 /* Turn on the watchdog timer */
#define WDIOS_TEMPPANIC 0x0004 /* Kernel panic on temperature trip */
-
+#define WDIOS_RUN_ON_REBOOT 0x0008 /* Keep watchdog enabled on reboot */
+#define WDIOS_STOP_ON_REBOOT 0x0010 /* Turn off the watchdog on reboot */
#endif /* _UAPI_LINUX_WATCHDOG_H */
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 WDIOS_RUN_ON_REBOOT and WDIOS_STOP_ON_REBOOT ioctl options to set up strategy on reboot. Signed-off-by: Dmitry Safonov <dima@arista.com> --- drivers/watchdog/watchdog_dev.c | 10 ++++++++++ include/linux/watchdog.h | 6 ++++++ include/uapi/linux/watchdog.h | 3 ++- 3 files changed, 18 insertions(+), 1 deletion(-)