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Message-id: <1420472882-10463-1-git-send-email-k.kozlowski@samsung.com>
Date: Mon, 05 Jan 2015 16:47:43 +0100
From: Krzysztof Kozlowski <k.kozlowski@...sung.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <lenb@...nel.org>,
Sebastian Reichel <sre@...nel.org>,
Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
David Woodhouse <dwmw2@...radead.org>,
Pavel Machek <pavel@....cz>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-acpi@...r.kernel.org, linux-pm@...r.kernel.org
Cc: Krzysztof Kozlowski <k.kozlowski@...sung.com>
Subject: [RFC PATCHv2 00/19] power_supply: Allow safe usage of power supply
Hi,
This is RFC, please don't apply yet but let me know if this approach
is OK.
TLDR
====
Patchset tries to fix following race scenario:
Thread 1: charger manager, CONSUMER
Thread 2: power supply driver, PROVIDER
THREAD 1 (charger manager) THREAD 2 (power supply driver)
========================== ==============================
psy = power_supply_get_by_name()
Driver unbind, .remove
power_supply_unregister()
Device fully removed
psy->get_property()
To properly fix the race the patchset:
1. Adds power_supply_get_property()-like API for safe access by consumer.
2. Moves ownership of power_supply structure from driver (provider) to
power supply core.
3. Adds power_supply_put() which will reclaim memory.
Description
===========
This is a little different than my previous approaches [1][2] for fixing
usage of power supply by some consumer, if driver implementing it is
unbound.
The patchset is quite big and touches power supply API so a lot of
changes in drivers are needed. These changes *are not finished yet*.
I've done them only for:
- bq24190_charger.c
- charger-manager.c
- max14577_charger.c
- max17040_battery.c
- max17042_battery.c
- sbs-battery.c
- tps65090-charger.c
So allyesconfig won't build.
If this approach is OK, I'll prepare full patchset changing all the
drivers.
My previous approach [1][2] limited the race but did not close it.
Still the consumer of power supply by calling power_supply_get_propert(psy...)
may reference invalid memory because the producer freed it.
Actually, because struct power_supply is exposed to consumers, the
core should be the owner of it. This is accomplished in patch 11/19
("power_supply: Change ownership from driver to core").
What the patchset does in steps
===============================
1. Some preparation steps are necessary - patch 1 and 2. The driver
implementing power supply won't be able to fill structure before
calling power_supply_register(). So 'power_supply_config'
is introduced in patch 2 ("power_supply: Move run-time configuration
to separate structure"). Unfortunately this touches all drivers.
2. Safe API wrappers (and usage counter) are added (power_supply_*()).
3. Patch 11: ownership of 'struct power_supply' is moved from driver
to the core.
4. power_supply_put() is added which reclaims resources.
The patchset is rebased on next-20141226. It should be pulled at once.
Bisectability is preserved.
Changes since v1
================
1. Add new patches (1, 2, 11, 19).
2. Preserved ack-s where there weren't any changes.
3. Patch 3: Add use counter.
4. Patch 3: Don't add wrapper for set_charged() because already exists
one.
[1] https://lkml.org/lkml/2014/11/4/527
[2] https://lkml.org/lkml/2014/10/16/89
Best regards,
Krzysztof
Krzysztof Kozlowski (19):
power_supply: Add driver private data
power_supply: Move run-time configuration to separate structure
power_supply: Add API for safe access of power supply function attrs
power_supply: sysfs: Use power_supply_*() API for accessing function
attrs
power: 88pm860x_charger: Use power_supply_*() API for accessing
function attrs
power: ab8500: Use power_supply_*() API for accessing function attrs
mfd: ab8500: Use power_supply_*() API for accessing function attrs
power: apm_power: Use power_supply_*() API for accessing function
attrs
power: bq2415x_charger: Use power_supply_*() API for accessing
function attrs
power: charger-manager: Use power_supply_*() API for accessing
function attrs
power_supply: Change ownership from driver to core
power_supply: Add power_supply_put for decrementing device reference
counter
power: charger-manager: Decrement the power supply's device reference
counter
x86/olpc/xo1/sci: Use newly added power_supply_put API
x86/olpc/xo15/sci: Use newly added power_supply_put API
power: 88pm860x_charger: Decrement the power supply's device reference
counter
power: bq2415x_charger: Decrement the power supply's device reference
counter
mfd: ab8500: Decrement the power supply's device reference counter
arm: mach-pxa: Decrement the power supply's device reference counter
arch/arm/mach-pxa/raumfeld.c | 4 +-
arch/x86/platform/olpc/olpc-xo1-sci.c | 4 +-
arch/x86/platform/olpc/olpc-xo15-sci.c | 4 +-
drivers/acpi/battery.c | 3 +-
drivers/mfd/ab8500-sysctrl.c | 9 +-
drivers/power/88pm860x_charger.c | 24 ++--
drivers/power/ab8500_btemp.c | 2 +-
drivers/power/ab8500_charger.c | 2 +-
drivers/power/ab8500_fg.c | 2 +-
drivers/power/abx500_chargalg.c | 4 +-
drivers/power/apm_power.c | 4 +-
drivers/power/bq2415x_charger.c | 9 +-
drivers/power/bq24190_charger.c | 103 ++++++++-------
drivers/power/charger-manager.c | 158 +++++++++++++----------
drivers/power/max14577_charger.c | 34 ++---
drivers/power/max17040_battery.c | 31 ++---
drivers/power/max17042_battery.c | 45 ++++---
drivers/power/power_supply_core.c | 223 ++++++++++++++++++++++++---------
drivers/power/power_supply_leds.c | 25 ++--
drivers/power/power_supply_sysfs.c | 24 ++--
drivers/power/sbs-battery.c | 71 +++++------
drivers/power/tps65090-charger.c | 43 ++++---
include/linux/power/charger-manager.h | 3 +-
include/linux/power_supply.h | 70 ++++++++---
24 files changed, 562 insertions(+), 339 deletions(-)
--
1.9.1
--
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