linux-kernel - Re: [PATCH] kernel/workqueue.c: need call device_remove_file() when failure occurs after called device_create

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Date:	Thu, 16 May 2013 11:33:24 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Tejun Heo <tj@...nel.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [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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