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| author | Dmitry Safonov <dima@arista.com> | 2020-02-23 11:49:39 +0000 |
|---|---|---|
| committer | Wim Van Sebroeck <wim@linux-watchdog.org> | 2020-03-18 11:15:24 +0100 |
| commit | 9232c80659e941ffa6c7bfc96bd64c6172ef0452 (patch) | |
| tree | 7fad86166df0b4d8c8c039f72d4af12cf86bb17b /drivers/watchdog | |
| parent | 3f9d51333129e16d77dcc9414bd548151d884c8a (diff) | |
| download | lwn-9232c80659e941ffa6c7bfc96bd64c6172ef0452.tar.gz lwn-9232c80659e941ffa6c7bfc96bd64c6172ef0452.zip | |
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 <linux@roeck-us.net>
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: linux-watchdog@vger.kernel.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200223114939.194754-1-dima@arista.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Diffstat (limited to 'drivers/watchdog')
| -rw-r--r-- | drivers/watchdog/watchdog_core.c | 12 |
1 files changed, 12 insertions, 0 deletions
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; |