linux-kernel - Re: [PATCH v8 0/3] PM / wakeup: Show wakeup sources stats in sysfs

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Date:   Mon, 26 Aug 2019 11:15:58 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Tri Vo <trong@...roid.com>
Cc:     gregkh@...uxfoundation.org, viresh.kumar@...aro.org,
        rafael@...nel.org, hridya@...gle.com, sspatil@...gle.com,
        kaleshsingh@...gle.com, ravisadineni@...omium.org,
        swboyd@...omium.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, kernel-team@...roid.com
Subject: Re: [PATCH v8 0/3] PM / wakeup: Show wakeup sources stats in sysfs

On Wednesday, August 7, 2019 3:48:43 AM CEST 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, create a
> 'struct device' to expose wakeup sources statistics in sysfs under
> /sys/class/wakeup/wakeup<ID>/*.
> 
> 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
> 
> v2:
> - 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
>   sysfs.
> 
> v3:
> 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
> 
> v4:
> - 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.
> 
> v5:
> - Removed CONFIG_PM_SLEEP_STATS
> - Used PTR_ERR_OR_ZERO instead of if(IS_ERR(...)) + PTR_ERR, reported by
>   kbuild test robot <lkp@...el.com>
> - 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.
> 
> v6:
> - 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.
> 
> v7:
> - 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.
> 
> v8:
> - 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
>   Stephen.
> 
> --
> 2.22.0.770.g0f2c4a37fd-goog
> 
> 

All three patches applied along with the later fixes from Stephen.

Thanks!