Re: [PATCH V4 17/20] watchdog/dev: Add tracepoints
From: Guenter Roeck
Date: Thu Jun 16 2022 - 19:55:35 EST
On 6/16/22 08:47, Daniel Bristot de Oliveira wrote:
On 6/16/22 15:44, Guenter Roeck wrote:
On 6/16/22 01:44, Daniel Bristot de Oliveira wrote:
Add a set of tracepoints, enabling the observability of the watchdog
device interactions with user-space.
The events are:
watchdog:watchdog_open
watchdog:watchdog_close
watchdog:watchdog_start
watchdog:watchdog_stop
watchdog:watchdog_set_timeout
watchdog:watchdog_ping
watchdog:watchdog_nowayout
watchdog:watchdog_set_keep_alive
watchdog:watchdog_keep_alive
watchdog:watchdog_set_pretimeout
watchdog:watchdog_pretimeout
Cc: Wim Van Sebroeck <wim@xxxxxxxxxxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Cc: Gabriele Paoloni <gpaoloni@xxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Clark Williams <williams@xxxxxxxxxx>
Cc: linux-doc@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-trace-devel@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
---
drivers/watchdog/watchdog_dev.c | 43 ++++++++++-
drivers/watchdog/watchdog_pretimeout.c | 2 +
include/linux/watchdog.h | 7 +-
include/trace/events/watchdog.h | 101 +++++++++++++++++++++++++
4 files changed, 143 insertions(+), 10 deletions(-)
create mode 100644 include/trace/events/watchdog.h
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 54903f3c851e..2f28dc5ab763 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -44,6 +44,9 @@
#include <linux/watchdog.h> /* For watchdog specific items */
#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
+#define CREATE_TRACE_POINTS
+#include <trace/events/watchdog.h>
+
#include "watchdog_core.h"
#include "watchdog_pretimeout.h"
@@ -130,9 +133,11 @@ static inline void watchdog_update_worker(struct
watchdog_device *wdd)
if (watchdog_need_worker(wdd)) {
ktime_t t = watchdog_next_keepalive(wdd);
- if (t > 0)
+ if (t > 0) {
hrtimer_start(&wd_data->timer, t,
HRTIMER_MODE_REL_HARD);
+ trace_watchdog_set_keep_alive(wdd, ktime_to_ms(t));
+ }
} else {
hrtimer_cancel(&wd_data->timer);
}
@@ -141,7 +146,7 @@ static inline void watchdog_update_worker(struct
watchdog_device *wdd)
static int __watchdog_ping(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data = wdd->wd_data;
- ktime_t earliest_keepalive, now;
+ ktime_t earliest_keepalive, now, next_keepalive;
int err;
earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,
@@ -149,14 +154,16 @@ static int __watchdog_ping(struct watchdog_device *wdd)
now = ktime_get();
if (ktime_after(earliest_keepalive, now)) {
- hrtimer_start(&wd_data->timer,
- ktime_sub(earliest_keepalive, now),
+ next_keepalive = ktime_sub(earliest_keepalive, now);
+ hrtimer_start(&wd_data->timer, next_keepalive,
HRTIMER_MODE_REL_HARD);
+ trace_watchdog_set_keep_alive(wdd, ktime_to_ms(next_keepalive));
return 0;
}
wd_data->last_hw_keepalive = now;
+ trace_watchdog_ping(wdd);
if (wdd->ops->ping)
err = wdd->ops->ping(wdd); /* ping the watchdog */
else
@@ -215,6 +222,7 @@ static void watchdog_ping_work(struct kthread_work *work)
wd_data = container_of(work, struct watchdog_core_data, work);
mutex_lock(&wd_data->lock);
+ trace_watchdog_keep_alive(wd_data->wdd);
if (watchdog_worker_should_ping(wd_data))
__watchdog_ping(wd_data->wdd);
mutex_unlock(&wd_data->lock);
@@ -250,6 +258,8 @@ static int watchdog_start(struct watchdog_device *wdd)
set_bit(_WDOG_KEEPALIVE, &wd_data->status);
+ trace_watchdog_start(wdd);
+
started_at = ktime_get();
if (watchdog_hw_running(wdd) && wdd->ops->ping) {
err = __watchdog_ping(wdd);
@@ -294,6 +304,7 @@ static int watchdog_stop(struct watchdog_device *wdd)
return -EBUSY;
}
+ trace_watchdog_stop(wdd);
if (wdd->ops->stop) {
clear_bit(WDOG_HW_RUNNING, &wdd->status);
err = wdd->ops->stop(wdd);
@@ -367,6 +378,7 @@ static int watchdog_set_timeout(struct watchdog_device *wdd,
if (watchdog_timeout_invalid(wdd, timeout))
return -EINVAL;
+ trace_watchdog_set_timeout(wdd, timeout);
The driver has no obligation to set the timeout to the
requested value. It might be more valuable to report both
the requested and the actual values.
Ack! how do I get the actual value?
Read it from the data structure after the driver function returned.
if (wdd->ops->set_timeout) {
err = wdd->ops->set_timeout(wdd, timeout);
} else {
@@ -399,6 +411,8 @@ static int watchdog_set_pretimeout(struct watchdog_device
*wdd,
if (watchdog_pretimeout_invalid(wdd, timeout))
return -EINVAL;
+ trace_watchdog_set_pretimeout(wdd, timeout);
+
Again, the driver has no obligation to set the timeout to the
requested value.
/me takes note.
if (wdd->ops->set_pretimeout && (wdd->info->options & WDIOF_PRETIMEOUT))
err = wdd->ops->set_pretimeout(wdd, timeout);
else
@@ -430,6 +444,23 @@ static int watchdog_get_timeleft(struct watchdog_device
*wdd,
return 0;
}
+/**
+ * watchdog_set_nowayout - set nowaout bit
+ * @wdd: The watchdog device to set nowayoutbit
+ * @nowayout A boolean on/off switcher
+ *
+ * If nowayout boolean is true, the nowayout option is set. No action is
+ * taken if nowayout is false.
+ */
+void watchdog_set_nowayout(struct watchdog_device *wdd, bool nowayout)
+{
+ if (nowayout) {
+ set_bit(WDOG_NO_WAY_OUT, &wdd->status);
+ trace_watchdog_nowayout(wdd);
+ }
+}
+EXPORT_SYMBOL(watchdog_set_nowayout);
+
#ifdef CONFIG_WATCHDOG_SYSFS
static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
char *buf)
@@ -861,6 +892,8 @@ static int watchdog_open(struct inode *inode, struct file
*file)
goto out_clear;
}
+ trace_watchdog_open(wdd);
+
err = watchdog_start(wdd);
if (err < 0)
goto out_mod;
@@ -883,6 +916,7 @@ static int watchdog_open(struct inode *inode, struct file
*file)
return stream_open(inode, file);
out_mod:
+ trace_watchdog_close(wdd);
module_put(wd_data->wdd->ops->owner);
out_clear:
clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
@@ -944,6 +978,7 @@ static int watchdog_release(struct inode *inode, struct
file *file)
/* make sure that /dev/watchdog can be re-opened */
clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
+ trace_watchdog_close(wdd);
done:
running = wdd && watchdog_hw_running(wdd);
mutex_unlock(&wd_data->lock);
diff --git a/drivers/watchdog/watchdog_pretimeout.c
b/drivers/watchdog/watchdog_pretimeout.c
index 376a495ab80c..58c391ed2205 100644
--- a/drivers/watchdog/watchdog_pretimeout.c
+++ b/drivers/watchdog/watchdog_pretimeout.c
@@ -8,6 +8,7 @@
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/watchdog.h>
+#include <trace/events/watchdog.h>
#include "watchdog_core.h"
#include "watchdog_pretimeout.h"
@@ -107,6 +108,7 @@ void watchdog_notify_pretimeout(struct watchdog_device *wdd)
return;
}
+ trace_watchdog_pretimeout(wdd);
wdd->gov->pretimeout(wdd);
spin_unlock_irqrestore(&pretimeout_lock, flags);
}
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 99660197a36c..11d93407e492 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -139,12 +139,7 @@ static inline bool watchdog_hw_running(struct
watchdog_device *wdd)
return test_bit(WDOG_HW_RUNNING, &wdd->status);
}
-/* Use the following function to set the nowayout feature */
-static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool
nowayout)
-{
- if (nowayout)
- set_bit(WDOG_NO_WAY_OUT, &wdd->status);
-}
+void watchdog_set_nowayout(struct watchdog_device *wdd, bool nowayout);
/* Use the following function to stop the watchdog on reboot */
static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd)
diff --git a/include/trace/events/watchdog.h b/include/trace/events/watchdog.h
new file mode 100644
index 000000000000..145cd6cfaa02
--- /dev/null
+++ b/include/trace/events/watchdog.h
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM watchdog
+
+#if !defined(_TRACE_WATCHDOG_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_WATCHDOG_H
+
+#include <linux/tracepoint.h>
+
+/*
+ * These are all events whose sole argument is the watchdog id.
+ */
+DECLARE_EVENT_CLASS(dev_operations_template,
+
+ TP_PROTO(struct watchdog_device *wdd),
+
+ TP_ARGS(wdd),
+
+ TP_STRUCT__entry(
+ __field(__u32, id)
+ ),
+
+ TP_fast_assign(
+ __entry->id = wdd->id;
+ ),
+
+ TP_printk("id=%d",
+ __entry->id)
+);
+
+DEFINE_EVENT(dev_operations_template, watchdog_open,
+ TP_PROTO(struct watchdog_device *wdd),
+ TP_ARGS(wdd));
+
+DEFINE_EVENT(dev_operations_template, watchdog_close,
+ TP_PROTO(struct watchdog_device *wdd),
+ TP_ARGS(wdd));
+
+DEFINE_EVENT(dev_operations_template, watchdog_start,
+ TP_PROTO(struct watchdog_device *wdd),
+ TP_ARGS(wdd));
+
+DEFINE_EVENT(dev_operations_template, watchdog_stop,
+ TP_PROTO(struct watchdog_device *wdd),
+ TP_ARGS(wdd));
+
+DEFINE_EVENT(dev_operations_template, watchdog_ping,
+ TP_PROTO(struct watchdog_device *wdd),
+ TP_ARGS(wdd));
+
+DEFINE_EVENT(dev_operations_template, watchdog_nowayout,
+ TP_PROTO(struct watchdog_device *wdd),
+ TP_ARGS(wdd));
+
+DEFINE_EVENT(dev_operations_template, watchdog_keep_alive,
+ TP_PROTO(struct watchdog_device *wdd),
+ TP_ARGS(wdd));
+
+DEFINE_EVENT(dev_operations_template, watchdog_pretimeout,
+ TP_PROTO(struct watchdog_device *wdd),
+ TP_ARGS(wdd));
+
+/*
+ * These are all events with a device ID and a given timeout.
+ */
+DECLARE_EVENT_CLASS(watchdog_timeout_template,
+
+ TP_PROTO(struct watchdog_device *wdd, u64 timeout),
+
+ TP_ARGS(wdd, timeout),
+
+ TP_STRUCT__entry(
+ __field(__u32, id)
+ __field(__u64, timeout)
Why u64 ? timeout is unsigned long.
ack! I will change it. (I am seeing unsigned int, am I missing something?).
Yes, you are correct.
Guenter