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SubjectRe: [PATCH] extcon: Release locking when sending the notification of connector state
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> Am 14.06.2018 um 12:39 schrieb H. Nikolaus Schaller <hns@goldelico.com>:
>
> 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.

I did take some minutes to check and it now also works again on the OMAP5EVM.

BR,
Nikolaus
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