power: supply: Use system freezable queue for power supply change event

I don't find so much change in power_supply_change work and even this happen in kernel 3.4 I don't find reason why we need to queue on a system_wq.

<4>[13502.656095] [<c0419264>] (sbs_read_word_data+0x0/0x70) from
[<c04192f8>] (sbs_set_battery_mode+0x24/0x6c)
<4>[13502.656095]  r6:d79b0800 r5:d7123408 r4:00000001 r3:c04194ac
<4>[13502.656125] [<c04192d4>] (sbs_set_battery_mode+0x0/0x6c) from
[<c041962c>] (sbs_get_property+0x180/0x6e4)
<4>[13502.656125]  r6:0000001b r5:d7123408 r4:d79b0800 r3:c04194ac
<4>[13502.656156] [<c04194ac>] (sbs_get_property+0x0/0x6e4) from
[<c0417e2c>] (power_supply_show_property+0x4c/0x1c8)
<4>[13502.656186] [<c0417de0>] (power_supply_show_property+0x0/0x1c8)
from [<c0418098>] (power_supply_uevent+0xa8/0x1d4)
<4>[13502.656186]  r8:ca4b1000 r7:0000001b r6:d7123408 r5:0000000e r4:c068d3dc
<4>[13502.656217] [<c0417ff0>] (power_supply_uevent+0x0/0x1d4) from
[<c0324f58>] (dev_uevent+0xc8/0x18c)
<4>[13502.656247] [<c0324e90>] (dev_uevent+0x0/0x18c) from
[<c025ce18>] (kobject_uevent_env+0x1d4/0x4c4)
<4>[13502.656247]  r7:d7882880 r6:00000000 r5:c069cda4 r4:00000002
<4>[13502.656278] [<c025cc44>] (kobject_uevent_env+0x0/0x4c4) from
[<c025d11c>] (kobject_uevent+0x14/0x18)
<4>[13502.656308] [<c025d108>] (kobject_uevent+0x0/0x18) from
[<c04178d0>] (power_supply_changed_work+0x94/0xb8)
<4>[13502.656308] [<c041783c>] (power_supply_changed_work+0x0/0xb8)
from [<c00603e8>] (process_one_work+0x158/0x474)
<4>[13502.656339]  r7:c1ae9e00 r6:c1ae4880 r5:cc480000 r4:ce655e00
<4>[13502.656369] [<c0060290>] (process_one_work+0x0/0x474) from
[<c0060a50>] (worker_thread+0x144/0x324)
<4>[13502.656369] [<c006090c>] (worker_thread+0x0/0x324) from
[<c00655c4>] (kthread+0x98/0xa4)
<4>[13502.656400] [<c006552c>] (kthread+0x0/0xa4) from [<c0047b6c>]

(do_exit+0x0/0x7c4)

---
 drivers/power/supply/power_supply_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 1e0960b..27a458f 100644
@@ -119,7 +119,7 @@ void power_supply_changed(struct power_supply *psy)
 	psy->changed = true;
 	pm_stay_awake(&psy->dev);
 	spin_unlock_irqrestore(&psy->changed_lock, flags);
-	schedule_work(&psy->changed_work);
+	queue_work(system_freezable_wq, &psy->chaged_work);
 }
 EXPORT_SYMBOL_GPL(power_supply_changed);
 

2.7.4

Just before suspend we can get the situation that a user process is trying to access the sysfs attribute of power supply. During resume we can hit the situation to have an invalid access to i2c bus that is still suspended. Make more sense to freeze the workqueue too

<4>[13502.656095] [<c0419264>] (sbs_read_word_data+0x0/0x70) from
[<c04192f8>] (sbs_set_battery_mode+0x24/0x6c)
<4>[13502.656095]  r6:d79b0800 r5:d7123408 r4:00000001 r3:c04194ac
<4>[13502.656125] [<c04192d4>] (sbs_set_battery_mode+0x0/0x6c) from
[<c041962c>] (sbs_get_property+0x180/0x6e4)
<4>[13502.656125]  r6:0000001b r5:d7123408 r4:d79b0800 r3:c04194ac
<4>[13502.656156] [<c04194ac>] (sbs_get_property+0x0/0x6e4) from
[<c0417e2c>] (power_supply_show_property+0x4c/0x1c8)
<4>[13502.656186] [<c0417de0>] (power_supply_show_property+0x0/0x1c8)
from [<c0418098>] (power_supply_uevent+0xa8/0x1d4)
<4>[13502.656186]  r8:ca4b1000 r7:0000001b r6:d7123408 r5:0000000e r4:c068d3dc
<4>[13502.656217] [<c0417ff0>] (power_supply_uevent+0x0/0x1d4) from
[<c0324f58>] (dev_uevent+0xc8/0x18c)
<4>[13502.656247] [<c0324e90>] (dev_uevent+0x0/0x18c) from
[<c025ce18>] (kobject_uevent_env+0x1d4/0x4c4)
<4>[13502.656247]  r7:d7882880 r6:00000000 r5:c069cda4 r4:00000002
<4>[13502.656278] [<c025cc44>] (kobject_uevent_env+0x0/0x4c4) from
[<c025d11c>] (kobject_uevent+0x14/0x18)
<4>[13502.656308] [<c025d108>] (kobject_uevent+0x0/0x18) from
[<c04178d0>] (power_supply_changed_work+0x94/0xb8)
<4>[13502.656308] [<c041783c>] (power_supply_changed_work+0x0/0xb8)
from [<c00603e8>] (process_one_work+0x158/0x474)
<4>[13502.656339]  r7:c1ae9e00 r6:c1ae4880 r5:cc480000 r4:ce655e00
<4>[13502.656369] [<c0060290>] (process_one_work+0x0/0x474) from
[<c0060a50>] (worker_thread+0x144/0x324)
<4>[13502.656369] [<c006090c>] (worker_thread+0x0/0x324) from
[<c00655c4>] (kthread+0x98/0xa4)
<4>[13502.656400] [<c006552c>] (kthread+0x0/0xa4) from [<c0047b6c>]

(do_exit+0x0/0x7c4)

---
Changes V1:
- fix typo in the code
- Add more information in the description

---
 drivers/power/supply/power_supply_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-

index 1e0960b..aa70853 100644
@@ -119,7 +119,7 @@ void power_supply_changed(struct power_supply *psy)
 	psy->changed = true;
 	pm_stay_awake(&psy->dev);
 	spin_unlock_irqrestore(&psy->changed_lock, flags);
-	schedule_work(&psy->changed_work);
+	queue_work(system_freezable_wq, &psy->changed_work);
 }
 EXPORT_SYMBOL_GPL(power_supply_changed);
 

2.7.4