lkml.org 
[lkml]   [2020]   [Feb]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCHv3] watchdog: Add stop_on_reboot parameter to control reboot policy
From
Date
On 2/23/20 3:49 AM, Dmitry Safonov wrote:
> 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>

> ---
> Changes:
> v3: Make module parameter read-only in runtime (Thanks Guenter for
> spotting the typo!)
> v2: Add module parameter instead of ioctl()
>
> 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;
>
>

\
 
 \ /
  Last update: 2020-02-23 15:10    [W:0.046 / U:0.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site