linux-kernel - Re: [PATCH] usb: gadget: udc_core: Use right kobj when calling sysfs

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Date:	Tue, 16 Sep 2014 08:46:07 +0200
From:	Andreas Larsson <andreas@...sler.com>
To:	balbi@...com, Peter Chen <peter.chen@...escale.com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	software@...sler.com
Subject: Re: [PATCH] usb: gadget: udc_core: Use right kobj when calling sysfs_notify

On 2014-09-16 07:15, Felipe Balbi wrote:
> Hi,
>
> On Tue, Sep 16, 2014 at 10:02:25AM +0800, Peter Chen wrote:
>> On Mon, Sep 15, 2014 at 12:42:27PM +0200, Andreas Larsson wrote:
>>> The state attribute is connected to the kobj of the udc, not the gadget.
>>>
>>> Signed-off-by: Andreas Larsson <andreas@...sler.com>
>>> ---
>>>   drivers/usb/gadget/udc/udc-core.c |   14 +++++++++++++-
>>>   1 file changed, 13 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
>>> index b0d9817..37c129a 100644
>>> --- a/drivers/usb/gadget/udc/udc-core.c
>>> +++ b/drivers/usb/gadget/udc/udc-core.c
>>> @@ -109,8 +109,20 @@ EXPORT_SYMBOL_GPL(usb_gadget_unmap_request);
>>>   static void usb_gadget_state_work(struct work_struct *work)
>>>   {
>>>   	struct usb_gadget	*gadget = work_to_gadget(work);
>>> +	struct usb_udc		*udc = NULL;
>>> +
>>> +	mutex_lock(&udc_lock);
>>> +	list_for_each_entry(udc, &udc_list, list)
>>> +		if (udc->gadget == gadget)
>>> +			goto found;
>>> +	mutex_unlock(&udc_lock);
>>> +
>>> +	return;
>>> +
>>> +found:
>>> +	mutex_unlock(&udc_lock);
>>>
>>> -	sysfs_notify(&gadget->dev.kobj, NULL, "state");
>>> +	sysfs_notify(&udc->dev.kobj, NULL, "state");
>>>   }
>>>
>>>   void usb_gadget_set_state(struct usb_gadget *gadget,
>>
>> What's the user mode difference with and without this patch?
>
> poll() will actually wakeup ?

Yes, that is indeed the difference.

Cheers,
Andreas Larsson
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