Re: [Patch] debugfs: remove module_exit()

[Cong Wang <amwang@redhat.com>]

On 12/01/10 23:56, Greg KH wrote:
> On Wed, Dec 01, 2010 at 02:33:12PM +0800, Cong Wang wrote:
>> On 12/01/10 09:35, Greg KH wrote:
>>> On Tue, Nov 09, 2010 at 04:19:58AM -0500, Amerigo Wang wrote:
>>>> debugfs can't be a module, so module_exit() is meaningless
>>>> for it.
>>>>
>>>> Signed-off-by: WANG Cong<amwang@redhat.com>
>>>>
>>>> ---
>>>> diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
>>>> index 37a8ca7..d38c88f 100644
>>>> --- a/fs/debugfs/inode.c
>>>> +++ b/fs/debugfs/inode.c
>>>> @@ -13,9 +13,6 @@
>>>>    *
>>>>    */
>>>>
>>>> -/* uncomment to get debug messages from the debug filesystem, ah the irony. */
>>>> -/* #define DEBUG */
>>>
>>> Why did you remove these lines?  They don't pertain to this patch.
>>
>> These lines are obsolete.
>
> Even if they were (and hint, I don't think they are), they have nothing
> to do with the patch you created so they don't belong here.  The rule is
> "one patch per logical change" and you didn't even describe that you
> were removing these lines in the changelog entry, so that's two strikes
> against removing these lines.
>

Ok, teach me where DEBUG is used in that file?


>>>> -
>>>>   #include<linux/module.h>
>>>>   #include<linux/fs.h>
>>>>   #include<linux/mount.h>
>>>> @@ -540,17 +537,5 @@ static int __init debugfs_init(void)
>>>>
>>>>   	return retval;
>>>>   }
>>>> -
>>>> -static void __exit debugfs_exit(void)
>>>> -{
>>>> -	debugfs_registered = false;
>>>> -
>>>> -	simple_release_fs(&debugfs_mount,&debugfs_mount_count);
>>>> -	unregister_filesystem(&debug_fs_type);
>>>> -	kobject_put(debug_kobj);
>>>> -}
>>>
>>> When the code is built into the kernel, the __exit function should go
>>> away, so this isn't costing us any extra memory, right?
>>
>>
>> Perhaps, but this can still reduce the vmlinux size, right?
>
> Which really doesn't matter, right?  How much is it reduced?
>
>>> And debugfs used to be able to be built as a module, perhaps it will be
>>> in the future?  I don't think this patch is really needed.
>>>
>>
>> Huh? Wasn't it a module before?
>
> Yes it was.
>
>> I think the problem is tracers use debugfs, it needs to depends on DEBUGFS=y.
>
> So if you disable tracing, then you could use debugfs as a module,
> right?  So the patch should not be applied.
>

No, that CONFIG is a bool, no way to make it as a module.
Since you insist, I will send a patch to make it as a module.

Thanks.