Re: [PATCH v2] PM / wakeup: show wakeup sources stats in sysfs

Greg KH
2019-06-28T15:10:46Z

On Thu, Jun 27, 2019 at 03:53:35PM -0700, Tri Vo wrote:
> Userspace can use wakeup_sources debugfs node to plot history of suspend
> blocking wakeup sources over device's boot cycle. This information can
> then be used (1) for power-specific bug reporting and (2) towards
> attributing battery consumption to specific processes over a period of
> time.
>
> However, debugfs doesn't have stable ABI. For this reason, expose wakeup
> sources statistics in sysfs under /sys/power/wakeup_sources/<name>/
>
> Embedding a struct kobject into struct wakeup_source changes lifetime
> requirements on the latter. To that end, change deallocation of struct
> wakeup_source using kfree to kobject_put().
>
> Change struct wakelock's wakeup_source member to a pointer to decouple
> lifetimes of struct wakelock and struct wakeup_source for above reason.
>
> Introduce CONFIG_PM_SLEEP_STATS that enables/disables showing wakeup
> source statistics in sysfs.
>
> Signed-off-by: Tri Vo <trong@android.com>

Ok, this looks much better, but I don't like the use of a "raw" kobject
here. It is much simpler, and less code, to use 'struct device'
instead.

As proof, I reworked the patch to do just that, and it saves over 50
lines of .c code, which is always nice :)

Attached below is the reworked code, along with the updated
documentation file. It creates devices in a virtual class, and you can
easily iterate over them all by looking in /sys/class/wakeup/.

Note, I'm note quite sure you need all of the changes you made in
kernel/power/wakelock.c when you make the structure contain a pointer to
the wakeup source and not the structure itself, but I just went with it
and got it all to build properly.

Also note, I've not actually tested this at all, only built it, so I
_strongly_ suggest that you test this to make sure it really works :)

What do you think?

thanks,

greg k-h

------------------

---
Documentation/ABI/testing/sysfs-power | 73 ++++++++++++-
drivers/base/power/Makefile | 1 +
drivers/base/power/wakeup.c | 11 +-
drivers/base/power/wakeup_stats.c | 144 ++++++++++++++++++++++++++
include/linux/pm_wakeup.h | 19 ++++
kernel/power/Kconfig | 10 ++
kernel/power/wakelock.c | 40 ++++---
7 files changed, 280 insertions(+), 18 deletions(-)
create mode 100644 drivers/base/power/wakeup_stats.c

diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index 18b7dc929234..ef92628e6fc3 100644
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -300,4 +300,75 @@ Description:
attempt.

Using this sysfs file will override any values that were
- set using the kernel command line for disk offset.
\ No newline at end of file
+ set using the kernel command line for disk offset.
+
+What: /sys/class/wakeup/
+Date: June 2019
+Contact: Tri Vo <trong@android.com>
+Description:
+ The /sys/class/wakeup/ directory contains pointers to all
+ wakeup sources in the kernel at that moment in time.
+
+What: /sys/class/wakeup/.../active_count
+Date: June 2019
+Contact: Tri Vo <trong@android.com>
+Description:
+ This file contains the number of times the wakeup source was
+ activated.
+
+What: /sys/class/wakeup/.../event_count
+Date: June 2019
+Contact: Tri Vo <trong@android.com>
+Description:
+ This file contains the number of signaled wakeup events
+ associated with the wakeup source.
+
+What: /sys/class/wakeup/.../wakeup_count
+Date: June 2019
+Contact: Tri Vo <trong@android.com>
+Description:
+ This file contains the number of times the wakeup source might
+ abort suspend.
+
+What: /sys/class/wakeup/.../expire_count
+Date: June 2019
+Contact: Tri Vo <trong@android.com>
+Description:
+ This file contains the number of times the wakeup source's
+ timeout has expired.
+
+What: /sys/class/wakeup/.../active_time_ms
+Date: June 2019
+Contact: Tri Vo <trong@android.com>
+Description:
+ This file contains the amount of time the wakeup source has
+ been continuously active, in milliseconds. If the wakeup
+ source is not active, this file contains '0'.
+
+What: /sys/class/wakeup/.../total_time_ms
+Date: June 2019
+Contact: Tri Vo <trong@android.com>
+Description:
+ This file contains the total amount of time this wakeup source
+ has been active, in milliseconds.
+
+What: /sys/class/wakeup/.../max_time_ms
+Date: June 2019
+Contact: Tri Vo <trong@android.com>
+Description:
+ This file contains the maximum amount of time this wakeup
+ source has been continuously active, in milliseconds.
+
+What: /sys/class/wakeup/.../last_change_ms
+Date: June 2019
+Contact: Tri Vo <trong@android.com>
+Description:
+ This file contains the monotonic clock time when the wakeup
+ source was touched last time, in milliseconds.
+
+What: /sys/class/wakeup/.../prevent_suspend_time_ms
+Date: June 2019
+Contact: Tri Vo <trong@android.com>
+Description:
+ The file contains the total amount of time this wakeup source
+ has been preventing autosleep, in milliseconds.
diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index e1bb691cf8f1..1963f53d9982 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_PM) += sysfs.o generic_ops.o common.o qos.o runtime.o wakeirq.o
obj-$(CONFIG_PM_SLEEP) += main.o wakeup.o
+obj-$(CONFIG_PM_SLEEP_STATS) += wakeup_stats.o
obj-$(CONFIG_PM_TRACE_RTC) += trace.o
obj-$(CONFIG_PM_GENERIC_DOMAINS) += domain.o domain_governor.o
obj-$(CONFIG_HAVE_CLK) += clock_ops.o
diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index 5b2b6a05a4f3..a5e5ffaa4532 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -147,8 +147,7 @@ void wakeup_source_destroy(struct wakeup_source *ws)

__pm_relax(ws);
wakeup_source_record(ws);
- kfree_const(ws->name);
- kfree(ws);
+ wakeup_source_sysfs_remove(ws);
}
EXPORT_SYMBOL_GPL(wakeup_source_destroy);

@@ -205,11 +204,15 @@ EXPORT_SYMBOL_GPL(wakeup_source_remove);
struct wakeup_source *wakeup_source_register(const char *name)
{
struct wakeup_source *ws;
+ int ret;

ws = wakeup_source_create(name);
- if (ws)
+ if (ws) {
+ ret = wakeup_source_sysfs_add(ws);
+ if (ret)
+ return NULL;
wakeup_source_add(ws);
-
+ }
return ws;
}
EXPORT_SYMBOL_GPL(wakeup_source_register);
diff --git a/drivers/base/power/wakeup_stats.c b/drivers/base/power/wakeup_stats.c
new file mode 100644
index 000000000000..e0c4767304be
--- /dev/null
+++ b/drivers/base/power/wakeup_stats.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Wakeup statistics in sysfs
+ *
+ * Copyright (c) 2019 Linux Foundation <gregkh@linuxfoundation.org>
+ * Copyright (c) 2019 Google Inc.
+ */
+
+#include <linux/slab.h>
+#include <linux/kdev_t.h>
+#include <linux/device.h>
+
+#include "power.h"
+
+static struct class *wakeup_class;
+
+#define wakeup_attr(_name) \
+static ssize_t _name##_show(struct device *dev, \
+ struct device_attribute *attr, char *buf) \
+{ \
+ struct wakeup_source *ws = dev_get_drvdata(dev); \
+ \
+ return sprintf(buf, "%lu\n", ws->_name); \
+} \
+static DEVICE_ATTR_RO(_name)
+
+wakeup_attr(active_count);
+wakeup_attr(event_count);
+wakeup_attr(wakeup_count);
+wakeup_attr(expire_count);
+
+static ssize_t active_time_ms_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct wakeup_source *ws = dev_get_drvdata(dev);
+ ktime_t active_time =
+ ws->active ? ktime_sub(ktime_get(), ws->last_time) : 0;
+
+ return sprintf(buf, "%lld\n", ktime_to_ms(active_time));
+}
+static DEVICE_ATTR_RO(active_time_ms);
+
+static ssize_t total_time_ms_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct wakeup_source *ws = dev_get_drvdata(dev);
+ ktime_t active_time;
+ ktime_t total_time = ws->total_time;
+
+ if (ws->active) {
+ active_time = ktime_sub(ktime_get(), ws->last_time);
+ total_time = ktime_add(total_time, active_time);
+ }
+ return sprintf(buf, "%lld\n", ktime_to_ms(total_time));
+}
+static DEVICE_ATTR_RO(total_time_ms);
+
+static ssize_t max_time_ms_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct wakeup_source *ws = dev_get_drvdata(dev);
+ ktime_t active_time;
+ ktime_t max_time = ws->max_time;
+
+ if (ws->active) {
+ active_time = ktime_sub(ktime_get(), ws->last_time);
+ if (active_time > max_time)
+ max_time = active_time;
+ }
+ return sprintf(buf, "%lld\n", ktime_to_ms(max_time));
+}
+static DEVICE_ATTR_RO(max_time_ms);
+
+static ssize_t last_change_ms_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct wakeup_source *ws = dev_get_drvdata(dev);
+
+ return sprintf(buf, "%lld\n", ktime_to_ms(ws->last_time));
+}
+static DEVICE_ATTR_RO(last_change_ms);
+
+static ssize_t prevent_suspend_time_ms_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct wakeup_source *ws = dev_get_drvdata(dev);
+ ktime_t prevent_sleep_time = ws->prevent_sleep_time;
+
+ if (ws->active && ws->autosleep_enabled) {
+ prevent_sleep_time = ktime_add(prevent_sleep_time,
+ ktime_sub(ktime_get(), ws->start_prevent_time));
+ }
+ return sprintf(buf, "%lld\n", ktime_to_ms(prevent_sleep_time));
+}
+static DEVICE_ATTR_RO(prevent_suspend_time_ms);
+
+static struct attribute *wakeup_source_attrs[] = {
+ &dev_attr_active_count.attr,
+ &dev_attr_event_count.attr,
+ &dev_attr_wakeup_count.attr,
+ &dev_attr_expire_count.attr,
+ &dev_attr_active_time_ms.attr,
+ &dev_attr_total_time_ms.attr,
+ &dev_attr_max_time_ms.attr,
+ &dev_attr_last_change_ms.attr,
+ &dev_attr_prevent_suspend_time_ms.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(wakeup_source);
+
+/**
+ * wakeup_source_sysfs_add - Add wakeup_source attributes to sysfs.
+ * @ws: Wakeup source to be exposed in sysfs.
+ */
+int wakeup_source_sysfs_add(struct wakeup_source *ws)
+{
+ struct device *dev;
+
+ dev = device_create_with_groups(wakeup_class, NULL, MKDEV(0, 0), ws,
+ wakeup_source_groups, "%s", ws->name);
+ if (IS_ERR(dev))
+ return PTR_ERR(dev);
+ ws->dev = dev;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(wakeup_source_sysfs_add);
+
+void wakeup_source_sysfs_remove(struct wakeup_source *ws)
+{
+ put_device(ws->dev);
+ device_unregister(ws->dev);
+}
+
+static int __init wakeup_sources_sysfs_init(void)
+{
+ wakeup_class = class_create(THIS_MODULE, "wakeup");
+ if (IS_ERR(wakeup_class))
+ return PTR_ERR(wakeup_class);
+
+ return 0;
+}
+
+postcore_initcall(wakeup_sources_sysfs_init);
diff --git a/include/linux/pm_wakeup.h b/include/linux/pm_wakeup.h
index ce57771fab9b..18ebc4ce817c 100644
--- a/include/linux/pm_wakeup.h
+++ b/include/linux/pm_wakeup.h
@@ -35,6 +35,7 @@ struct wake_irq;
* @relax_count: Number of times the wakeup source was deactivated.
* @expire_count: Number of times the wakeup source's timeout has expired.
* @wakeup_count: Number of times the wakeup source might abort suspend.
+ * @dev: struct device for sysfs statistics about the wakeup source
* @active: Status of the wakeup source.
* @has_timeout: The wakeup source has been activated with a timeout.
*/
@@ -55,6 +56,7 @@ struct wakeup_source {
unsigned long relax_count;
unsigned long expire_count;
unsigned long wakeup_count;
+ struct device *dev;
bool active:1;
bool autosleep_enabled:1;
};
@@ -181,6 +183,23 @@ static inline void pm_wakeup_dev_event(struct device *dev, unsigned int msec,

#endif /* !CONFIG_PM_SLEEP */

+#ifdef CONFIG_PM_SLEEP_STATS
+
+/* drivers/base/power/wakeup_stats.c */
+int wakeup_source_sysfs_add(struct wakeup_source *ws);
+void wakeup_source_sysfs_remove(struct wakeup_source *ws);
+
+#else /* !CONFIG_PM_SLEEP_STATS */
+
+static inline int wakeup_source_sysfs_add(struct wakeup_source *ws)
+{
+ return 0;
+}
+static inline void wakeup_source_sysfs_remove(struct wakeup_source *ws)
+{ }
+
+#endif /* !CONFIG_PM_SLEEP_STATS */
+
static inline void wakeup_source_init(struct wakeup_source *ws,
const char *name)
{
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index ff8592ddedee..4d258f34020b 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -195,6 +195,16 @@ config PM_SLEEP_DEBUG
def_bool y
depends on PM_DEBUG && PM_SLEEP

+config PM_SLEEP_STATS
+ bool "Wakeup sources statistics"
+ depends on PM_SLEEP
+ help
+ Expose wakeup sources statistics to user space via sysfs. Collected
+ statistics are located under /sys/power/wakeup_sources. For more
+ information, read <file:Documentation/ABI/testing/sysfs-power>.
+
+ If in doubt, say N.
+
config DPM_WATCHDOG
bool "Device suspend/resume watchdog"
depends on PM_DEBUG && PSTORE && EXPERT
diff --git a/kernel/power/wakelock.c b/kernel/power/wakelock.c
index 4210152e56f0..dce02c2f4496 100644
--- a/kernel/power/wakelock.c
+++ b/kernel/power/wakelock.c
@@ -27,7 +27,7 @@ static DEFINE_MUTEX(wakelocks_lock);
struct wakelock {
char *name;
struct rb_node node;
- struct wakeup_source ws;
+ struct wakeup_source *ws;
#ifdef CONFIG_PM_WAKELOCKS_GC
struct list_head lru;
#endif
@@ -46,7 +46,7 @@ ssize_t pm_show_wakelocks(char *buf, bool show_active)

for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) {
wl = rb_entry(node, struct wakelock, node);
- if (wl->ws.active == show_active)
+ if (wl->ws->active == show_active)
str += scnprintf(str, end - str, "%s ", wl->name);
}
if (str > buf)
@@ -112,16 +112,16 @@ static void __wakelocks_gc(struct work_struct *work)
u64 idle_time_ns;
bool active;

- spin_lock_irq(&wl->ws.lock);
- idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws.last_time));
- active = wl->ws.active;
- spin_unlock_irq(&wl->ws.lock);
+ spin_lock_irq(&wl->ws->lock);
+ idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws->last_time));
+ active = wl->ws->active;
+ spin_unlock_irq(&wl->ws->lock);

if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC))
break;

if (!active) {
- wakeup_source_remove(&wl->ws);
+ wakeup_source_remove(wl->ws);
rb_erase(&wl->node, &wakelocks_tree);
list_del(&wl->lru);
kfree(wl->name);
@@ -153,6 +153,7 @@ static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
struct rb_node **node = &wakelocks_tree.rb_node;
struct rb_node *parent = *node;
struct wakelock *wl;
+ int ret;

while (*node) {
int diff;
@@ -187,9 +188,22 @@ static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
kfree(wl);
return ERR_PTR(-ENOMEM);
}
- wl->ws.name = wl->name;
- wl->ws.last_time = ktime_get();
- wakeup_source_add(&wl->ws);
+
+ wl->ws = wakeup_source_create(wl->name);
+ if (!wl->ws) {
+ kfree(wl);
+ return ERR_PTR(-ENOMEM);
+ }
+ wl->ws->last_time = ktime_get();
+
+ ret = wakeup_source_sysfs_add(wl->ws);
+ if (ret) {
+ kfree(wl->name);
+ kfree(wl);
+ return ERR_PTR(ret);
+ }
+
+ wakeup_source_add(wl->ws);
rb_link_node(&wl->node, parent, node);
rb_insert_color(&wl->node, &wakelocks_tree);
wakelocks_lru_add(wl);
@@ -233,9 +247,9 @@ int pm_wake_lock(const char *buf)
u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;

do_div(timeout_ms, NSEC_PER_MSEC);
- __pm_wakeup_event(&wl->ws, timeout_ms);
+ __pm_wakeup_event(wl->ws, timeout_ms);
} else {
- __pm_stay_awake(&wl->ws);
+ __pm_stay_awake(wl->ws);
}

wakelocks_lru_most_recent(wl);
@@ -271,7 +285,7 @@ int pm_wake_unlock(const char *buf)
ret = PTR_ERR(wl);
goto out;
}
- __pm_relax(&wl->ws);
+ __pm_relax(wl->ws);

wakelocks_lru_most_recent(wl);
wakelocks_gc();
--
2.22.0