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power: supply: bq27xxx: Fix poll_interval handling and races on remove

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Before this patch bq27xxx_battery_teardown() was setting poll_interval = 0
to avoid bq27xxx_battery_update() requeuing the delayed_work item.

There are 2 problems with this:

1. If the driver is unbound through sysfs, rather then the module being
   rmmod-ed, this changes poll_interval unexpectedly

2. This is racy, after it being set poll_interval could be changed
   before bq27xxx_battery_update() checks it through
   /sys/module/bq27xxx_battery/parameters/poll_interval

Fix this by added a removed attribute to struct bq27xxx_device_info and
using that instead of setting poll_interval to 0.

There also is another poll_interval related race on remove(), writing
/sys/module/bq27xxx_battery/parameters/poll_interval will requeue
the delayed_work item for all devices on the bq27xxx_battery_devices
list and the device being removed was only removed from that list
after cancelling the delayed_work item.

Fix this by moving the removal from the bq27xxx_battery_devices list
to before cancelling the delayed_work item.

Fixes: 8cfaaa8118 ("bq27x00_battery: Fix OOPS caused by unregistring bq27x00 driver")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
This commit is contained in:
Hans de Goede 2023-04-15 20:23:34 +02:00 committed by Sebastian Reichel
parent 444ff00734
commit c00bc80462
2 changed files with 10 additions and 13 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

22
drivers/power/supply/bq27xxx_battery.c
View file

@ -1801,7 +1801,7 @@ static void bq27xxx_battery_update_unlocked(struct bq27xxx_device_info *di)
di->last_update = jiffies;
if (poll_interval > 0)
if (!di->removed && poll_interval > 0)
mod_delayed_work(system_wq, &di->work, poll_interval * HZ);
}
@ -2132,22 +2132,18 @@ EXPORT_SYMBOL_GPL(bq27xxx_battery_setup);
void bq27xxx_battery_teardown(struct bq27xxx_device_info *di)
{
/*
* power_supply_unregister call bq27xxx_battery_get_property which
* call bq27xxx_battery_poll.
* Make sure that bq27xxx_battery_poll will not call
* schedule_delayed_work again after unregister (which cause OOPS).
*/
poll_interval = 0;
cancel_delayed_work_sync(&di->work);
power_supply_unregister(di->bat);
mutex_lock(&bq27xxx_list_lock);
list_del(&di->list);
mutex_unlock(&bq27xxx_list_lock);
/* Set removed to avoid bq27xxx_battery_update() re-queuing the work */
mutex_lock(&di->lock);
di->removed = true;
mutex_unlock(&di->lock);
cancel_delayed_work_sync(&di->work);
power_supply_unregister(di->bat);
mutex_destroy(&di->lock);
}
EXPORT_SYMBOL_GPL(bq27xxx_battery_teardown);

1
include/linux/power/bq27xxx_battery.h
View file

@ -68,6 +68,7 @@ struct bq27xxx_device_info {
struct bq27xxx_access_methods bus;
struct bq27xxx_reg_cache cache;
int charge_design_full;
bool removed;
unsigned long last_update;
struct delayed_work work;
struct power_supply *bat;