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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 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.


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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