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SubjectRe: [PATCH] kernel/workqueue.c: need call device_remove_file() when failure occurs after called device_create_file()
On 05/16/2013 11:33 AM, Chen Gang wrote:
> On 05/16/2013 05:22 AM, Tejun Heo wrote:
>> On Wed, May 15, 2013 at 02:13:14PM +0800, Chen Gang wrote:
>>>
>>> In workqueue_sysfs_register(), when failure occurs after called
>>> device_create_file(), need call device_remove_file() to release the
>>> related resources, then call device_unregister().
>>>
>>> Or it will cause issue.
>>>
>>> For individual 'device_attributs' (just like our case), need call
>>> device_remove_file() explictly and then call device_unregister(),
>>> please reference drivers/base/*.c (e.g node.c or cpu.c).
>>
>> Hmm... isn't this already taken care of by __sysfs_remove_dir() which
>> device_unregister() calls? That function removes all non-directory
>> files under the directory being removed.
>>
>
> It just like what you said:
> device_unregister() ->
> kobject_del() ->
> sysfs_remove_dir() ->
> __sysfs_remove_dir() ->
> sysfs_remove_one()
> But:
> device_remove_file() ->
> sysfs_remove_file() ->
> ...
> sysfs_attr_ns() ->
> ops->namespace() (such as device_namespace() in workqueue.c)
> ...
> sysfs_hash_and_remove() ->
> sysfs_remove_one().
>
> So if not call device_remove_file() explicitly, the device_namespace()
> may be not called.
>

It seems, if not call ops->namespace(), it still is OK. To get a result,
it still has much details to continue to read.

But all together, reference the related code of another subsystems, we
really need device_remove_file() before call device_unregister().


>
> Even in device_unregister(), it still call device_remove_file() to
> release the related attributes firstly, then call kobject_del().
>
>
>
> Thanks.
>


--
Chen Gang

Asianux Corporation


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