Watchdog is not turned off in kernel panic situation.
In certain systems this might prevent the successful loading
of kdump kernel. The kdump kernel might hit a watchdog reset
while it is booting.
To avoid such scenarios add a panic notifier call back function
which can stop the watchdog. This provision can be enabled by
passing watchdog.stop_on_panic=1 via kernel command-line parameter.
Signed-off-by: George Cherian <george.cher...@marvell.com>
---
drivers/watchdog/watchdog_core.c | 35 ++++++++++++++++++++++++++++++++
include/linux/watchdog.h | 2 ++
2 files changed, 37 insertions(+)
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index d46d8c8c01f2..f0006d90da92 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -34,6 +34,7 @@
#include <linux/idr.h> /* For ida_* macros */
#include <linux/err.h> /* For IS_ERR macros */
#include <linux/of.h> /* For of_get_timeout_sec */
+#include <linux/panic_notifier.h> /* For panic handler */
#include <linux/suspend.h>
#include "watchdog_core.h" /* For watchdog_dev_register/... */
@@ -47,6 +48,9 @@ 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)");
+static bool stop_on_panic;
+module_param(stop_on_panic, bool, 0444);
+MODULE_PARM_DESC(stop_on_panic, "Stop watchdogs on panic (0=keep watching,
1=stop)");
/*
* Deferred Registration infrastructure.
*
@@ -155,6 +159,23 @@ int watchdog_init_timeout(struct watchdog_device *wdd,
}
EXPORT_SYMBOL_GPL(watchdog_init_timeout);
+static int watchdog_panic_notify(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct watchdog_device *wdd;
+
+ wdd = container_of(nb, struct watchdog_device, panic_nb);
+ if (watchdog_active(wdd)) {
+ int ret;
+
+ ret = wdd->ops->stop(wdd);
+ if (ret)
+ return NOTIFY_BAD;
+ }
+
+ return NOTIFY_DONE;
+}
+
static int watchdog_reboot_notifier(struct notifier_block *nb,
unsigned long code, void *data)
{
@@ -334,6 +355,17 @@ static int ___watchdog_register_device(struct
watchdog_device *wdd)
wdd->id, ret);
}
+ if (stop_on_panic) {
+ if (wdd->ops->stop && !(wdd->info->options &
WDIOF_STOP_MAYSLEEP)) {
+ wdd->panic_nb.notifier_call = watchdog_panic_notify;
+ atomic_notifier_chain_register(&panic_notifier_list,
+ &wdd->panic_nb);
+ set_bit(WDOG_STOP_ON_PANIC, &wdd->status);
+ } else {
+ pr_warn("watchdog%d: stop_on_panic not supported\n",
wdd->id);
+ }
+ }
+
return 0;
}
@@ -390,6 +422,9 @@ static void __watchdog_unregister_device(struct
watchdog_device *wdd)
if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status))
unregister_reboot_notifier(&wdd->reboot_nb);
+ if (test_bit(WDOG_STOP_ON_PANIC, &wdd->status))
+ atomic_notifier_chain_unregister(&panic_notifier_list,
+ &wdd->panic_nb);
watchdog_dev_unregister(wdd);
ida_free(&watchdog_ida, wdd->id);
}
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 99660197a36c..ef6f1136a4c5 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -108,6 +108,7 @@ struct watchdog_device {
struct notifier_block reboot_nb;
struct notifier_block restart_nb;
struct notifier_block pm_nb;
+ struct notifier_block panic_nb;
void *driver_data;
struct watchdog_core_data *wd_data;
unsigned long status;
@@ -118,6 +119,7 @@ struct watchdog_device {
#define WDOG_HW_RUNNING 3 /* True if HW watchdog running
*/
#define WDOG_STOP_ON_UNREGISTER 4 /* Should be stopped on
unregister */
#define WDOG_NO_PING_ON_SUSPEND 5 /* Ping worker should be
stopped on suspend */
+#define WDOG_STOP_ON_PANIC 6 /* Should be stopped on panic for
loading kdump kernels */
struct list_head deferred;
};
--
2.34.1
