From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760380Ab3LISiA (ORCPT ); Mon, 9 Dec 2013 13:38:00 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:52871 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755804Ab3LISh6 (ORCPT ); Mon, 9 Dec 2013 13:37:58 -0500 Date: Mon, 9 Dec 2013 10:39:27 -0800 From: Greg KH To: Ethan Zhao Cc: konrad.wilk@oracle.com, raghavendra.kt@linux.vnet.ibm.com, LKML Subject: Re: [PATCH v3] xen/debugfs: Check debugfs initialization before using it Message-ID: <20131209183927.GB28986@kroah.com> References: <1386583012-506-1-git-send-email-ethan.kernel@gmail.com> <20131209111900.GC6562@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 09:49:36PM +0800, Ethan Zhao wrote: > On Mon, Dec 9, 2013 at 7:19 PM, Greg KH wrote: > > 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? > > > What I want to ask who is so smart and fake some many functions when > CONFIG_DEBUG_FS is not configured/defined and the build could pass > without any error ? That's the way this has always worked. > What is the motive make him wrote some many fake function and why he > wrote the debugfs_initialized() function seem 'useless' at all ? To make the caller code easier, and smaller, and to not care if debugfs is enabled in the kernel build or not at all. Ok, I answered your questions, now care to answer mine? greg k-h