The change adds a simple watchdog pretimeout framework infrastructure,
its purpose is to allow users to select a desired handling of watchdog
pretimeout events, which may be generated by some watchdog devices.
A user selects a default watchdog pretimeout governor during
compilation stage.
Watchdogs with WDIOF_PRETIMEOUT capability now have two device
attributes in sysfs: pretimeout to display currently set pretimeout
value and pretimeout_governor attribute to display the selected
watchdog pretimeout governor.
Watchdogs with no WDIOF_PRETIMEOUT capability has no changes in
sysfs, and such watchdog devices do not require the framework.
Signed-off-by: Vladimir Zapolskiy <vladimir_zapols...@mentor.com>
---
Changes from v2 to v3:
* essentially simplified the implementation due to removal of runtime
dynamic selection of watchdog pretimeout governors by a user, this
feature is supposed to be added later on
* removed support of sleepable watchdog pretimeout governors
* moved sysfs device attributes to watchdog_dev.c, this required to
add exported watchdog_pretimeout_governor_name() interface
* if pretimeout framework is not selected, then pretimeout event
ends up in kernel panic -- this behaviour as a default one was asked
by Guenter
Changes from v1 to v2:
* removed framework private bits from struct watchdog_governor,
* centralized compile-time selection of a default governor in
watchdog_pretimeout.h,
* added can_sleep option, now only sleeping governors (e.g. userspace)
will be executed in a special workqueue,
* changed fallback logic, if a governor in use is removed, now this
situation is not possible, because in use governors have non-zero
module refcount
drivers/watchdog/Kconfig | 8 ++
drivers/watchdog/Makefile | 5 +-
drivers/watchdog/watchdog_core.c | 9 +++
drivers/watchdog/watchdog_dev.c | 16 ++++
drivers/watchdog/watchdog_pretimeout.c | 134 +++++++++++++++++++++++++++++++++
drivers/watchdog/watchdog_pretimeout.h | 42 +++++++++++
include/linux/watchdog.h | 13 ++++
7 files changed, 226 insertions(+), 1 deletion(-)
create mode 100644 drivers/watchdog/watchdog_pretimeout.c
create mode 100644 drivers/watchdog/watchdog_pretimeout.h
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index b54f26c..354217e 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1800,4 +1800,12 @@ config USBPCWATCHDOG
Most people will say N.
+comment "Watchdog Pretimeout Governors"
+
+config WATCHDOG_PRETIMEOUT_GOV
+ bool "Enable watchdog pretimeout governors"
+ default n
+ help
+ The option allows to select watchdog pretimeout governors.
+
endif # WATCHDOG
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a46e7c1..cca47de 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -3,9 +3,12 @@
#
# The WatchDog Timer Driver Core.
-watchdog-objs += watchdog_core.o watchdog_dev.o
obj-$(CONFIG_WATCHDOG_CORE) += watchdog.o
+watchdog-objs += watchdog_core.o watchdog_dev.o
+
+watchdog-$(CONFIG_WATCHDOG_PRETIMEOUT_GOV) += watchdog_pretimeout.o
+
# Only one watchdog can succeed. We probe the ISA/PCI/USB based
# watchdog-cards first, then the architecture specific watchdog
# drivers and then the architecture independent "softdog" driver.
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 7c3ba58..ae6c23a 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -40,6 +40,7 @@
#include <linux/of.h> /* For of_get_timeout_sec */
#include "watchdog_core.h" /* For watchdog_dev_register/... */
+#include "watchdog_pretimeout.h"
static DEFINE_IDA(watchdog_ida);
@@ -244,6 +245,13 @@ static int __watchdog_register_device(struct
watchdog_device *wdd)
}
}
+ ret = watchdog_register_pretimeout(wdd);
+ if (ret) {
+ watchdog_dev_unregister(wdd);
+ ida_simple_remove(&watchdog_ida, wdd->id);
+ return ret;
+ }
+
if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
@@ -251,6 +259,7 @@ static int __watchdog_register_device(struct
watchdog_device *wdd)
if (ret) {
pr_err("watchdog%d: Cannot register reboot notifier
(%d)\n",
wdd->id, ret);
+ watchdog_unregister_pretimeout(wdd);
watchdog_dev_unregister(wdd);
ida_simple_remove(&watchdog_ida, wdd->id);
return ret;
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 87bbae7..c0fd743 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -49,6 +49,7 @@
#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
#include "watchdog_core.h"
+#include "watchdog_pretimeout.h"
/*
* struct watchdog_core_data - watchdog core internal data
@@ -452,6 +453,16 @@ static ssize_t pretimeout_show(struct device *dev,
}
static DEVICE_ATTR_RO(pretimeout);
+static ssize_t pretimeout_governor_show(struct device *dev,
+ struct device_attribute *devattr,
+ char *buf)
+{
+ struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+ return watchdog_pretimeout_governor_name(wdd, buf);
+}
+static DEVICE_ATTR_RO(pretimeout_governor);
+
static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
int n)
{
@@ -466,6 +477,10 @@ static umode_t wdt_is_visible(struct kobject *kobj, struct
attribute *attr,
else if (attr == &dev_attr_pretimeout.attr &&
!(wdd->info->options & WDIOF_PRETIMEOUT))
mode = 0;
+ else if (attr == &dev_attr_pretimeout_governor.attr &&
+ !((wdd->info->options & WDIOF_PRETIMEOUT) &&
+ IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
+ mode = 0;
return mode;
}
@@ -478,6 +493,7 @@ static struct attribute *wdt_attrs[] = {
&dev_attr_status.attr,
&dev_attr_nowayout.attr,
&dev_attr_pretimeout.attr,
+ &dev_attr_pretimeout_governor.attr,
NULL,
};
diff --git a/drivers/watchdog/watchdog_pretimeout.c
b/drivers/watchdog/watchdog_pretimeout.c
new file mode 100644
index 0000000..ebfc3d6
--- /dev/null
+++ b/drivers/watchdog/watchdog_pretimeout.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2015-2016 Mentor Graphics
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/watchdog.h>
+
+#include "watchdog_pretimeout.h"
+
+/* Default watchdog pretimeout governor */
+static struct watchdog_governor *default_gov;
+
+/* The spinlock protects wdd->gov and pretimeout_list */
+static DEFINE_SPINLOCK(pretimeout_lock);
+
+/* List of watchdog devices, which can generate a pretimeout event */
+static LIST_HEAD(pretimeout_list);
+
+struct watchdog_pretimeout {
+ struct watchdog_device *wdd;
+ struct list_head entry;
+};
+
+int watchdog_pretimeout_governor_name(struct watchdog_device *wdd, char *buf)
+{
+ int count = 0;
+
+ spin_lock_irq(&pretimeout_lock);
+ if (wdd->gov)
+ count = sprintf(buf, "%s\n", wdd->gov->name);
+ else
+ count = sprintf(buf, "N/A\n");
+ spin_unlock_irq(&pretimeout_lock);
+
+ return count;
+}
+
+void watchdog_notify_pretimeout(struct watchdog_device *wdd)
+{
+ unsigned long flags;
+
+ if (!wdd)
+ return;
+
+ spin_lock_irqsave(&pretimeout_lock, flags);
+ if (!wdd->gov) {
+ spin_unlock_irqrestore(&pretimeout_lock, flags);
+ return;
+ }
+
+ wdd->gov->pretimeout(wdd);
+ spin_unlock_irqrestore(&pretimeout_lock, flags);
+}
+EXPORT_SYMBOL_GPL(watchdog_notify_pretimeout);
+
+int watchdog_register_governor(struct watchdog_governor *gov)
+{
+ struct watchdog_pretimeout *p;
+
+ if (!gov || !gov->name || !gov->pretimeout ||
+ strlen(gov->name) >= WATCHDOG_GOV_NAME_MAXLEN)
+ return -EINVAL;
+
+ if (default_gov)
+ return -EBUSY;
+
+ spin_lock_irq(&pretimeout_lock);
+ list_for_each_entry(p, &pretimeout_list, entry)
+ if (!p->wdd->gov)
+ p->wdd->gov = gov;
+ spin_unlock_irq(&pretimeout_lock);
+
+ default_gov = gov;
+
+ return 0;
+}
+
+void watchdog_unregister_governor(struct watchdog_governor *gov)
+{
+ if (!gov)
+ return;
+
+ if (default_gov == gov)
+ default_gov = NULL;
+}
+
+int watchdog_register_pretimeout(struct watchdog_device *wdd)
+{
+ struct watchdog_pretimeout *p;
+
+ if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+ return 0;
+
+ p = kzalloc(sizeof(*p), GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+
+ spin_lock_irq(&pretimeout_lock);
+ list_add(&p->entry, &pretimeout_list);
+ p->wdd = wdd;
+ wdd->gov = default_gov;
+ spin_unlock_irq(&pretimeout_lock);
+
+ return 0;
+}
+
+void watchdog_unregister_pretimeout(struct watchdog_device *wdd)
+{
+ struct watchdog_pretimeout *p;
+
+ if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+ return;
+
+ spin_lock_irq(&pretimeout_lock);
+ wdd->gov = NULL;
+
+ list_for_each_entry(p, &pretimeout_list, entry) {
+ if (p->wdd == wdd) {
+ list_del(&p->entry);
+ break;
+ }
+ }
+ spin_unlock_irq(&pretimeout_lock);
+
+ kfree(p);
+}
diff --git a/drivers/watchdog/watchdog_pretimeout.h
b/drivers/watchdog/watchdog_pretimeout.h
new file mode 100644
index 0000000..9e08d56
--- /dev/null
+++ b/drivers/watchdog/watchdog_pretimeout.h
@@ -0,0 +1,42 @@
+#ifndef __WATCHDOG_PRETIMEOUT_H
+#define __WATCHDOG_PRETIMEOUT_H
+
+#define WATCHDOG_GOV_NAME_MAXLEN 20
+
+struct watchdog_device;
+
+struct watchdog_governor {
+ const char name[WATCHDOG_GOV_NAME_MAXLEN];
+ void (*pretimeout)(struct watchdog_device *wdd);
+};
+
+#if IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)
+/* Interfaces to watchdog pretimeout governors */
+int watchdog_register_governor(struct watchdog_governor *gov);
+void watchdog_unregister_governor(struct watchdog_governor *gov);
+
+/* Interfaces to watchdog_core.c */
+int watchdog_register_pretimeout(struct watchdog_device *wdd);
+void watchdog_unregister_pretimeout(struct watchdog_device *wdd);
+
+/* Interfaces to watchdog_dev.c */
+int watchdog_pretimeout_governor_name(struct watchdog_device *wdd, char *buf);
+
+#else
+static inline int watchdog_register_pretimeout(struct watchdog_device *wdd)
+{
+ return 0;
+}
+
+static inline void watchdog_unregister_pretimeout(struct watchdog_device *wdd)
+{
+}
+
+static inline int watchdog_pretimeout_governor_name(struct watchdog_device
*wdd,
+ char *buf)
+{
+ return 0;
+}
+#endif
+
+#endif
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index e3d23d3..0d18113 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -19,6 +19,7 @@
struct watchdog_ops;
struct watchdog_device;
struct watchdog_core_data;
+struct watchdog_governor;
/** struct watchdog_ops - The watchdog-devices operations
*
@@ -61,6 +62,7 @@ struct watchdog_ops {
* watchdog device.
* @info: Pointer to a watchdog_info structure.
* @ops: Pointer to the list of watchdog operations.
+ * @gov: Pointer to watchdog pretimeout governor.
* @bootstatus: Status of the watchdog device at boot.
* @timeout: The watchdog devices timeout value (in seconds).
* @min_timeout:The watchdog devices minimum timeout value (in seconds).
@@ -95,6 +97,7 @@ struct watchdog_device {
const struct attribute_group **groups;
const struct watchdog_info *info;
const struct watchdog_ops *ops;
+ const struct watchdog_governor *gov;
unsigned int bootstatus;
unsigned int timeout;
unsigned int pretimeout;
@@ -183,6 +186,16 @@ static inline void *watchdog_get_drvdata(struct
watchdog_device *wdd)
return wdd->driver_data;
}
+/* Use the following functions to report watchdog pretimeout event */
+#if IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)
+void watchdog_notify_pretimeout(struct watchdog_device *wdd);
+#else
+static inline void watchdog_notify_pretimeout(struct watchdog_device *wdd)
+{
+ panic("watchdog pretimeout event\n");
+}
+#endif
+
/* drivers/watchdog/watchdog_core.c */
void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
extern int watchdog_init_timeout(struct watchdog_device *wdd,
--
2.5.0
