Attr Groups in sysfs.

Gasparini Andrea gaspa at
Mon Apr 18 10:29:57 EDT 2011


On Mon, Apr 18, 2011 at 4:14 PM, Greg KH <greg at> wrote:
>> I'm missing only the myattr_group name... anyone has a clue of how can
>> I access this?
> You can't.


>> And adding to my kobject this way:
>>     retval = sysfs_create_group(mykobj, &my_attr_group_0);
> Ick, no, please don't do that, you want the group to be created before
> the device shows up to userspace, otherwise you just raced with
> userspace and bad things will happen.

Understand, you're completely right.
I'll try to refactor in a different way to avoid race.

> Why are you using a struct kobject directly and not a struct device
> instead?  Please don't use kobjects unless you are doing something very
> strange, and even then, please reconsider.
> Care to explain what you are using sysfs for?

Sure, It's quite complicated, in fact ;)
I'm doing an "extension" for a video device, in terms of a module that
handle some addictional logic that do some sort of stats about the
stream passed through it.
For example, I've a certain number of areas inside a frame, given in
form of (x,y,width,heigth) that behave to the same device, so I'd like
to call them: mydev/region_{0,1,2...}/{x,y,width,height}

That's why I'd like to have the "region_0" name, so I can distinguish
between the right attribute group.

Too caotic perhaps? (suggestions and existing examples are obviuosly welcome)

> thanks,

Thank *you* ;)

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