From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933326Ab3LILR1 (ORCPT ); Mon, 9 Dec 2013 06:17:27 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:49135 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932599Ab3LILR0 (ORCPT ); Mon, 9 Dec 2013 06:17:26 -0500 Date: Mon, 9 Dec 2013 03:19:00 -0800 From: Greg KH To: Ethan Zhao Cc: konrad.wilk@oracle.com, raghavendra.kt@linux.vnet.ibm.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] xen/debugfs: Check debugfs initialization before using it Message-ID: <20131209111900.GC6562@kroah.com> References: <1386583012-506-1-git-send-email-ethan.kernel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1386583012-506-1-git-send-email-ethan.kernel@gmail.com> User-Agent: Mutt/1.5.22 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 09, 2013 at 05:56:52PM +0800, Ethan Zhao wrote: > From: "ethan.zhao" > > 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 > --- > 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?