Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753183AbdFUC4v (ORCPT ); Tue, 20 Jun 2017 22:56:51 -0400 Received: from mail-ot0-f194.google.com ([74.125.82.194]:33464 "EHLO mail-ot0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752922AbdFUC4u (ORCPT ); Tue, 20 Jun 2017 22:56:50 -0400 MIME-Version: 1.0 In-Reply-To: <20170620211637.2590-1-bp@alien8.de> References: <20170620211637.2590-1-bp@alien8.de> From: Ethan Zhao Date: Wed, 21 Jun 2017 10:56:48 +0800 Message-ID: Subject: Re: [PATCH] x86/MCE, xen/mcelog: Make /dev/mcelog registration messages more precise To: Borislav Petkov Cc: X86 ML , LKML , Tony Luck , linux-edac , "" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2428 Lines: 66 Borislav, How about skipping the misc_register() steps and keep silence if you know it is running as Dom0 ? as it is easy to know. Reviewed-by: Ethan Zhao On Wed, Jun 21, 2017 at 5:16 AM, Borislav Petkov wrote: > From: Juergen Gross > > When running under Xen as dom0, /dev/mcelog is being provided by Xen > instead of the normal mcelog character device of the MCE core. Convert > an error message being issued by the MCE core in this case to an > informative message that Xen has registered the device. > > Signed-off-by: Juergen Gross > Cc: Tony Luck > Cc: linux-edac > Cc: x86-ml > Cc: xen-devel@lists.xenproject.org > Link: http://lkml.kernel.org/r/20170614084059.19294-1-jgross@suse.com > [ Massage a bit. ] > Signed-off-by: Borislav Petkov > --- > arch/x86/kernel/cpu/mcheck/dev-mcelog.c | 8 +++++++- > drivers/xen/mcelog.c | 2 ++ > 2 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/cpu/mcheck/dev-mcelog.c b/arch/x86/kernel/cpu/mcheck/dev-mcelog.c > index a80427c30c93..10cec43aac38 100644 > --- a/arch/x86/kernel/cpu/mcheck/dev-mcelog.c > +++ b/arch/x86/kernel/cpu/mcheck/dev-mcelog.c > @@ -415,9 +415,15 @@ static __init int dev_mcelog_init_device(void) > /* register character device /dev/mcelog */ > err = misc_register(&mce_chrdev_device); > if (err) { > - pr_err("Unable to init device /dev/mcelog (rc: %d)\n", err); > + if (err == -EBUSY) > + /* Xen dom0 might have registered the device already. */ > + pr_info("Unable to init device /dev/mcelog, already registered"); > + else > + pr_err("Unable to init device /dev/mcelog (rc: %d)\n", err); > + > return err; > } > + > mce_register_decode_chain(&dev_mcelog_nb); > return 0; > } > diff --git a/drivers/xen/mcelog.c b/drivers/xen/mcelog.c > index a493c7315e94..6cc1c15bcd84 100644 > --- a/drivers/xen/mcelog.c > +++ b/drivers/xen/mcelog.c > @@ -408,6 +408,8 @@ static int __init xen_late_init_mcelog(void) > if (ret) > goto deregister; > > + pr_info("/dev/mcelog registered by Xen\n"); > + > return 0; > > deregister: > -- > 2.13.0 >