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

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: 8cfaaa811894 ("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>

diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c
index 79aedf83cc8dddbcd10f029b196724025de20959..7411f1cf741bc339302699670e25214634dcf1b3 100644 (file)
--- a/drivers/power/supply/bq27xxx_battery.c
+++ b/drivers/power/supply/bq27xxx_battery.c
@@ -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);

diff --git a/include/linux/power/bq27xxx_battery.h b/include/linux/power/bq27xxx_battery.h
index a1aa68141d0b54615bddc2b2eaa8774b85e1dca1..e3322dad9c85cbccb0dfe868bb006589f59d302c 100644 (file)
--- a/include/linux/power/bq27xxx_battery.h
+++ b/include/linux/power/bq27xxx_battery.h
@@ -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;