Re: [PoC 2/7] Add kobject to super_block

[Goldwyn Rodrigues <rgoldwyn@suse.de>]

On 04/28/2016 09:26 PM, Al Viro wrote:
> On Thu, Apr 28, 2016 at 09:01:17PM -0500, Goldwyn Rodrigues wrote:
>> @@ -167,7 +204,8 @@ static void destroy_super(struct super_block *s)
>>   	WARN_ON(!list_empty(&s->s_mounts));
>>   	kfree(s->s_subtype);
>>   	kfree(s->s_options);
>> -	call_rcu(&s->rcu, destroy_super_rcu);
>> +	if (s->s_type->fs_flags & FS_CREATE_SYSFS)
>> +		kobject_del(&s->s_kobj);
>
> So we have kobject_del() under a spinlock.  Wonderful...  Better yet,
> you have the sodding kobjects sitting around well past the point when
> the filesystem driver has gone through rmmod.
>
> sysfs: lifetime rules made simple.  So simple that they don't fit a lot of
> situations, but hey - it sure *looks* easy to use...
>
> NAK.  If you want a description of super_block life cycle, I can describe it
> to you.  But please, don't play with it until you understand it.
>


Yes, I understand what you are trying to say. Using kobject to destroy 
super_block does not make sense in the current scenario.

Thanks for your feedback.

-- 
Goldwyn