Re: [PATCH v3] xen/debugfs: Check debugfs initialization before using it

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Dec 09, 2013 at 05:56:52PM +0800, Ethan Zhao wrote:
> From: "ethan.zhao" <ethan.kernel@gmail.com>
> 
> Should check debugfs initialization with debugfs_initialized() before using it,
> Because if it isn't initialized, the return value of fake debugfs_create_dir() etc
> functions would be ERR_PTR(-ENODEV), checking with NULL will not work.
> 
> V3: add warning message when debugfs not configured or disabled.

That's not what this patch does...

> Signed-off-by: ethan.zhao <ethan.kernel@gmail.com>
> ---
>  arch/x86/xen/debugfs.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/x86/xen/debugfs.c b/arch/x86/xen/debugfs.c
> index c8377fb..85c0e0e 100644
> --- a/arch/x86/xen/debugfs.c
> +++ b/arch/x86/xen/debugfs.c
> @@ -9,12 +9,18 @@ static struct dentry *d_xen_debug;
>  
>  struct dentry * __init xen_init_debugfs(void)
>  {
> +	if (!debugfs_initialized()) {
> +		d_xen_debug = NULL;
> +		goto nodebugfs;
> +	}

Again, why is this even needed?

What problem in the existing code are you trying to solve?