[PATCH v8 0/3] PM / wakeup: Show wakeup sources stats in sysfs

From: Tri Vo
Date: Tue Aug 06 2019 - 21:49:22 EST

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

However, debugfs doesn't have stable ABI. For this reason, create a
'struct device' to expose wakeup sources statistics in sysfs under

Patch 1 and 2 do some cleanup to simplify our changes to how wakeup sources are
created. Patch 3 implements wakeup sources stats in sysfs.

Tri Vo (3):
PM / wakeup: Drop wakeup_source_init(), wakeup_source_prepare()
PM / wakeup: Use wakeup_source_register() in wakelock.c
PM / wakeup: Show wakeup sources stats in sysfs

Documentation/ABI/testing/sysfs-class-wakeup | 76 +++++++
drivers/acpi/device_pm.c | 3 +-
drivers/base/power/Makefile | 2 +-
drivers/base/power/power.h | 9 +
drivers/base/power/wakeup.c | 59 +++---
drivers/base/power/wakeup_stats.c | 203 +++++++++++++++++++
fs/eventpoll.c | 4 +-
include/linux/pm_wakeup.h | 21 +-
kernel/power/autosleep.c | 2 +-
kernel/power/wakelock.c | 32 +--
kernel/time/alarmtimer.c | 2 +-
11 files changed, 358 insertions(+), 55 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-class-wakeup
create mode 100644 drivers/base/power/wakeup_stats.c

- Updated Documentation/ABI/, as per Greg.
- Removed locks in attribute functions, as per Greg.
- Lifetimes of struct wakelock and struck wakeup_source are now different due to
the latter embedding a refcounted kobject. Changed it so that struct wakelock
only has a pointer to struct wakeup_source, instead of embedding it.
- Added CONFIG_PM_SLEEP_STATS that enables/disables wakeup source statistics in

Changes by Greg:
- Reworked code to use 'struct device' instead of raw kobjects.
- Updated documentation file.
- Only link wakeup_stats.o when CONFIG_PM_SLEEP_STATS is enabled.
Changes by Tri:
- Reverted changes to kernel/power/wakelock.c. 'struct device' hides kobject
operations. So no need to handle lifetimes in wakelock.c

- Added 'Co-developed-by:' and 'Tested-by:' fields to commit message.
- Moved new documentation to a separate file
Documentation/ABI/testing/sysfs-class-wakeup, as per Greg.
- Fixed copyright header in drivers/base/power/wakeup_stats.c, as per Greg.

- Used PTR_ERR_OR_ZERO instead of if(IS_ERR(...)) + PTR_ERR, reported by
kbuild test robot <lkp@xxxxxxxxx>
- Stephen reported that a call to device_init_wakeup() and writing 'enabled' to
that device's power/wakeup file results in multiple wakeup source being
allocated for that device. Changed device_wakeup_enable() to check if device
wakeup was previously enabled.
Changes by Stephen:
- Changed stats location from /sys/class/wakeup/<name>/* to
/sys/class/wakeup/wakeup<ID>/*, where ID is an IDA-allocated integer. This
avoids name collisions in /sys/class/wakeup/ directory.
- Added a "name" attribute to wakeup sources, and updated documentation.
- Device registering the wakeup source is now the parent of the wakeup source.
Updated wakeup_source_register()'s signature and its callers accordingly.

- Changed stats location to /sys/class/wakeup/ws<ID>/*
- Replaced ida_simple_get()/ida_simple_remove() with ida_alloc()/ida_free() as
the former is deprecated.
- Reverted changes to device_init_wakeup(). Rafael is preparing a patch to deal
with extra wakeup source allocation in a separate patch.

- Removed wakeup_source_init(), wakeup_source_prepare().
- Removed duplicate wakeup source creation code from kernel/power/wakelock.
- Moved ID allocation to wakeup source object creation time.
- Changed stats location back to /sys/class/wakeup/wakeup<ID>/*
- Remove wakeup source device's "power" attributes.

- Updated commit message on patch 1 to indicate change of behavior of
wakeup_source_create(), as per Stephen.
- Included headers for used symbols, as per Stephen.
- Added a function to create wakeup source devices to use
device_set_pm_not_required() to skip power management for such devices, as per