Re: [RFC] fix sysfs symlinks

[viro@parcelfarce.linux.theplanet.co.uk]

On Thu, Apr 29, 2004 at 06:33:53PM +0530, Maneesh Soni wrote:

[snip]

> @@ -167,10 +175,14 @@ void sysfs_rename_dir(struct kobject * k
>  	parent = kobj->parent->dentry;
>  
>  	down(&parent->d_inode->i_sem);
> -
>  	new_dentry = sysfs_get_dentry(parent, new_name);
> -	d_move(kobj->dentry, new_dentry);
> -	kobject_set_name(kobj,new_name);
> +	if (!IS_ERR(new_dentry)) {
> +		down_write(&sysfs_rename_sem);
> +		d_move(kobj->dentry, new_dentry);
> +		kobject_set_name(kobj,new_name);
> +		up_write(&sysfs_rename_sem);
> +		dput(new_dentry);
> +	}
>  	up(&parent->d_inode->i_sem);	
>  }

I would probably lift that rwsem all way up - in front of any other locks
in sysfs_rename_dir().  Note that kobject_set_name() can very well lead to
allocations, so just to make the lock hierarchy cleaner...  Another thing:
please, check that new_dentry is negative here.  Other than that, I've
got no problems with the patch.