Messages in this thread | | | Date | Wed, 21 Jan 2015 16:22:17 +0100 | From | Sebastian Reichel <> | Subject | Re: [RFC PATCHv2 00/19] power_supply: Allow safe usage of power supply |
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Hi Krzysztof,
On Mon, Jan 05, 2015 at 04:47:43PM +0100, Krzysztof Kozlowski wrote: > This is RFC, please don't apply yet but let me know if this approach > is OK.
I just reviewed the patchset. It looks fine to me.
> 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.
Looks fine to me, thanks for doing this :)
> 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.
Please do :)
> 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.
$ grep -l power_supply_register **/*.c | grep -v mod.c | grep -v drivers/power drivers/acpi/ac.c drivers/acpi/battery.c drivers/acpi/sbs.c drivers/hid/hid-input.c drivers/hid/hid-sony.c drivers/hid/hid-wiimote-modules.c drivers/hid/wacom_sys.c drivers/platform/x86/compal-laptop.c drivers/staging/nvec/nvec_power.c
Please make sure to CC the respective maintainers for the patchset (e.g. current patch 14 and 15 should have CC'd x86 maintainers), so that they can Acknowledge the patchset.
> 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.
Looks fine to me.
> The patchset is rebased on next-20141226. It should be pulled at once. > Bisectability is preserved.
Fine with me, but I need acks from all involved maintainers. So for the patchset:
Reviewed-By: Sebastian Reichel <sre@kernel.org>
-- Sebastian [unhandled content-type:application/pgp-signature] | |