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SubjectRe: [PATCH] extcon: Release locking when sending the notification of connector state
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Hi Roger and Chanwoo,

> Am 14.06.2018 um 12:18 schrieb Chanwoo Choi <cw00.choi@samsung.com>:
>
> + H. Nikolaus Schaller <hns@goldelico.com>
>
> On 2018년 06월 14일 13:14, Chanwoo Choi wrote:
>> Previously, extcon used the spinlock before calling the notifier_call_chain
>> to prevent the scheduled out of task and to prevent the notification delay.
>> When spinlock is locked for sending the notification, deadlock issue
>> occured on the side of extcon consumer device. To fix this issue,
>> extcon consumer device should always use the work. it is always not
>> reasonable to use work.
>>
>> To fix this issue on extcon consumer device, release locking when sending
>> the notification of connector state.
>>
>> Fixes: ab11af049f88 ("extcon: Add the synchronization extcon APIs to support the notification")
>> Cc: stable@vger.kernel.org
>> Cc: Roger Quadros <rogerq@ti.com>
>> Cc: Kishon Vijay Abraham I <kishon@ti.com>
>> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
>> ---
>> drivers/extcon/extcon.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
>> index 8bff5fd18185..f75b08a45d4e 100644
>> --- a/drivers/extcon/extcon.c
>> +++ b/drivers/extcon/extcon.c
>> @@ -433,8 +433,8 @@ int extcon_sync(struct extcon_dev *edev, unsigned int id)
>> return index;
>>
>> spin_lock_irqsave(&edev->lock, flags);
>> -
>> state = !!(edev->state & BIT(index));
>> + spin_unlock_irqrestore(&edev->lock, flags);
>>
>> /*
>> * Call functions in a raw notifier chain for the specific one
>> @@ -448,6 +448,7 @@ int extcon_sync(struct extcon_dev *edev, unsigned int id)
>> */
>> raw_notifier_call_chain(&edev->nh_all, state, edev);
>>
>> + spin_lock_irqsave(&edev->lock, flags);
>> /* This could be in interrupt handler */
>> prop_buf = (char *)get_zeroed_page(GFP_ATOMIC);
>> if (!prop_buf) {
>>

I have tested on the Pyra handheld prototype and now it works. Plugging in an OTG cable
enables/disables OTG power as expected and there are no kernel oops any more.

So you can add my

Reported-by: H. Nikolaus Schaller <hns@goldelico.com>
Tested-by: H. Nikolaus Schaller <hns@goldelico.com>

BR and thank you for the quick fix,
Nikolaus
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