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Commit c9126384 authored Apr 15, 2023 by Hans de Goede Committed by Greg Kroah-Hartman May 30, 2023

power: supply: bq27xxx: Fix bq27xxx_battery_update() race condition



commit 5c34c0aef185dcd10881847b9ebf20046aa77cb4 upstream.

bq27xxx_battery_update() assumes / requires that it is only run once,
not multiple times at the same time. But there are 3 possible callers:

1. bq27xxx_battery_poll() delayed_work item handler
2. bq27xxx_battery_irq_handler_thread() I2C IRQ handler
3. bq27xxx_battery_setup()

And there is no protection against these racing with each other,
fix this race condition by making all callers take di->lock:

- Rename bq27xxx_battery_update() to bq27xxx_battery_update_unlocked()

- Add new bq27xxx_battery_update() which takes di->lock and then calls
  bq27xxx_battery_update_unlocked()

- Make stale cache check code in bq27xxx_battery_get_property(), which
  already takes di->lock directly to check the jiffies, call
  bq27xxx_battery_update_unlocked() instead of messing with
  the delayed_work item

- Make bq27xxx_battery_update_unlocked() mod the delayed-work item
  so that the next poll is delayed to poll_interval milliseconds after
  the last update independent of the source of the update

Fixes: 740b755a ("bq27x00: Poll battery state")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent ecd120ea

drivers/power/supply/bq27xxx_battery.c

+13 −8

Original line number	Diff line number	Diff line
		@@ -1551,7 +1551,7 @@ static int bq27xxx_battery_read_health(struct bq27xxx_device_info *di)
		return POWER_SUPPLY_HEALTH_GOOD;
		}

		void bq27xxx_battery_update(struct bq27xxx_device_info *di)
		static void bq27xxx_battery_update_unlocked(struct bq27xxx_device_info *di)
		{
		struct bq27xxx_reg_cache cache = {0, };
		bool has_ci_flag = di->opts & BQ27XXX_O_ZERO;
		@@ -1599,6 +1599,16 @@ void bq27xxx_battery_update(struct bq27xxx_device_info *di)
		di->cache = cache;

		di->last_update = jiffies;

		if (poll_interval > 0)
		mod_delayed_work(system_wq, &di->work, poll_interval * HZ);
		}

		void bq27xxx_battery_update(struct bq27xxx_device_info *di)
		{
		mutex_lock(&di->lock);
		bq27xxx_battery_update_unlocked(di);
		mutex_unlock(&di->lock);
		}
		EXPORT_SYMBOL_GPL(bq27xxx_battery_update);

		@@ -1609,9 +1619,6 @@ static void bq27xxx_battery_poll(struct work_struct *work)
		work.work);

		bq27xxx_battery_update(di);

		if (poll_interval > 0)
		schedule_delayed_work(&di->work, poll_interval * HZ);
		}

		/*
		@@ -1772,10 +1779,8 @@ static int bq27xxx_battery_get_property(struct power_supply *psy,
		struct bq27xxx_device_info *di = power_supply_get_drvdata(psy);

		mutex_lock(&di->lock);
		if (time_is_before_jiffies(di->last_update + 5 * HZ)) {
		cancel_delayed_work_sync(&di->work);
		bq27xxx_battery_poll(&di->work.work);
		}
		if (time_is_before_jiffies(di->last_update + 5 * HZ))
		bq27xxx_battery_update_unlocked(di);
		mutex_unlock(&di->lock);

		if (psp != POWER_SUPPLY_PROP_PRESENT && di->cache.flags < 0)