From: Dmitry Safonov <dima@arista.com>
To: linux-kernel@vger.kernel.org
Cc: Dmitry Safonov <0x7f454c46@gmail.com>,
Dmitry Safonov <dima@arista.com>,
Guenter Roeck <linux@roeck-us.net>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
linux-watchdog@vger.kernel.org
Subject: [PATCHv2] watchdog: Add stop_on_reboot parameter to control reboot policy
Date: Fri, 14 Feb 2020 16:22:09 +0000 [thread overview]
Message-ID: <20200214162209.129107-1-dima@arista.com> (raw)
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>
---
Changes v1 => 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..5ead96199a0b 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, 0644);
+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;
--
2.25.0
next reply other threads:[~2020-02-14 16:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 16:22 Dmitry Safonov [this message]
2020-02-22 16:06 ` [PATCHv2] watchdog: Add stop_on_reboot parameter to control reboot policy Guenter Roeck
2020-02-23 11:21 ` Dmitry Safonov
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