Re: [RFC Add in_use attribute] Let the driver know if it's in use

[Michael Trimarchi <trimarchi@gandalf.sssup.it>]

Greg KH wrote:
> On Tue, Apr 21, 2009 at 08:43:28AM +0200, Michael Trimarchi wrote:
>   
>>>>> Exactly, what are you trying to do that differs from
>>>>> device_for_each_child()?
>>>>>   
>>>>>       
>>>>>           
>>>> Is device for each child use to visist the first level of the tree?
>>>>     
>>>>         
>>> Have you tried it?
>>>   
>>>       
>> No, I take a look at the code.
>>
>> int device_for_each_child(struct device *parent, void *data,
>>                           int (*fn)(struct device *dev, void *data))
>> {
>>         struct klist_iter i;
>>         struct device *child;
>>         int error = 0;
>>
>>         klist_iter_init(&parent->p->klist_children, &i);
>>
>> I was thinking that the klist_children is the fist_level one children, 
>> so each time
>> a device is registerd it add the link to the parent.
>>     
>
> Yes it does.
>
> But you have to start at some device, right?  So you don't need to
> iterate over it, just go from there on down if needed.
>   
I start for a device, go down until I find a leaf or find that the 
subtree is marked.
Mark the leaf and go up and take the next node like the walk_tg_tree. 
The difference is
that I skip subtree if they are mark in_use.
> So I don't see why this helper function is needed at all yet, shouldn't
> we be doing the check within the normal suspend device walk of the tree?
>   
Sorry but here I need some help here. Where is the walk of the device 
tree during suspend?
> thanks,
>
> greg k-h
>
>   
Michael