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Date: Thu, 16 Jun 2022 06:44:35 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Daniel Bristot de Oliveira <bristot@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>
Cc: Wim Van Sebroeck <wim@...ux-watchdog.org>,
Jonathan Corbet <corbet@....net>,
Ingo Molnar <mingo@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Will Deacon <will@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Marco Elver <elver@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
"Paul E. McKenney" <paulmck@...nel.org>,
Shuah Khan <skhan@...uxfoundation.org>,
Gabriele Paoloni <gpaoloni@...hat.com>,
Juri Lelli <juri.lelli@...hat.com>,
Clark Williams <williams@...hat.com>,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-trace-devel@...r.kernel.org
Subject: Re: [PATCH V4 17/20] watchdog/dev: Add tracepoints
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@...ux-watchdog.org>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Jonathan Corbet <corbet@....net>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Will Deacon <will@...nel.org>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Marco Elver <elver@...gle.com>
> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: "Paul E. McKenney" <paulmck@...nel.org>
> Cc: Shuah Khan <skhan@...uxfoundation.org>
> Cc: Gabriele Paoloni <gpaoloni@...hat.com>
> Cc: Juri Lelli <juri.lelli@...hat.com>
> Cc: Clark Williams <williams@...hat.com>
> Cc: linux-doc@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: linux-trace-devel@...r.kernel.org
> Signed-off-by: Daniel Bristot de Oliveira <bristot@...nel.org>
> ---
> 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.
> 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.
> 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.
> + ),
> +
> + TP_fast_assign(
> + __entry->id = wdd->id;
> + __entry->timeout = timeout;
> + ),
> +
> + TP_printk("id=%d timeout=%llus",
> + __entry->id, __entry->timeout)
> +);
> +
> +DEFINE_EVENT(watchdog_timeout_template, watchdog_set_timeout,
> + TP_PROTO(struct watchdog_device *wdd, u64 timeout),
> + TP_ARGS(wdd, timeout));
> +
> +DEFINE_EVENT(watchdog_timeout_template, watchdog_set_pretimeout,
> + TP_PROTO(struct watchdog_device *wdd, u64 timeout),
> + TP_ARGS(wdd, timeout));
> +
> +DEFINE_EVENT(watchdog_timeout_template, watchdog_set_keep_alive,
> + TP_PROTO(struct watchdog_device *wdd, u64 timeout),
> + TP_ARGS(wdd, timeout));
> +
> +#endif /* _TRACE_WATCHDOG_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
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