From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753765AbdFMTa3 (ORCPT ); Tue, 13 Jun 2017 15:30:29 -0400 Received: from smtprelay0072.hostedemail.com ([216.40.44.72]:53232 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752168AbdFMTa2 (ORCPT ); Tue, 13 Jun 2017 15:30:28 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::::::::::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1542:1593:1594:1711:1730:1747:1777:1792:2393:2559:2562:2693:2828:3138:3139:3140:3141:3142:3355:3622:3865:3866:3867:3868:3870:3871:3872:3873:3874:4321:4605:5007:7903:8660:10004:10400:10848:11026:11232:11657:11658:11914:12043:12438:12740:12760:12895:13095:13148:13230:13255:13439:13972:14181:14659:14721:21080:21212:21433:21451:21627:30012:30054:30070:30076:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:2,LUA_SUMMARY:none X-HE-Tag: ants98_20b12f8f4661a X-Filterd-Recvd-Size: 3455 Message-ID: <1497382223.18751.23.camel@perches.com> Subject: Re: [PATCH v2] xen/mce: don't issue error message for failed /dev/mcelog registration From: Joe Perches To: Juergen Gross , Ingo Molnar Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org, boris.ostrovsky@oracle.com, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, tony.luck@intel.com, bp@alien8.de Date: Tue, 13 Jun 2017 12:30:23 -0700 In-Reply-To: <3a7376bd-1a93-1bc2-f7b6-f2a95f641a5d@suse.com> References: <20170613134507.16983-1-jgross@suse.com> <20170613152014.tax42aevmsfdopxa@gmail.com> <498f5ad7-c203-9b21-c153-e3496755b88d@suse.com> <1497371514.18751.17.camel@perches.com> <3a7376bd-1a93-1bc2-f7b6-f2a95f641a5d@suse.com> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.22.6-1ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2017-06-13 at 21:27 +0200, Juergen Gross wrote: > On 13/06/17 18:31, Joe Perches wrote: > > On Tue, 2017-06-13 at 18:13 +0200, Juergen Gross wrote: > > > On 13/06/17 17:20, Ingo Molnar wrote: > > > > * Juergen Gross wrote: > > > > > > > > > When running under Xen as dom0 /dev/mcelog is being registered by Xen > > > > > instead of the normal mcelog driver. Avoid an error message being > > > > > issued by the mcelog driver in this case. Instead issue an informative > > > > > message that Xen has registered the device. > > > > [] > > > > > diff --git a/arch/x86/kernel/cpu/mcheck/dev-mcelog.c b/arch/x86/kernel/cpu/mcheck/dev-mcelog.c > > > > [] > > > > > @@ -388,9 +388,16 @@ 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); > > > > > - return 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; > > > > > + } > > > > > > > > Please only use balanced curly braces in conditional statements. > > > > > > Okay, will change. > > > > Perhaps better is to reverse the test > > > > if (err != -EBUSY) { > > pr_err("Unable to ....", err); > > return err; > > } > > pr_info("etc..."); > > Okay. > > > > > [ rest of code at this indentation ] > > > > but it looks like you added a logic defect too and > > this code should be: > > > > if (err) { > > if (err == -EBUSY) > > pr_info(...) > > else > > pr_err(...) > > return err; > > } > > > > or less indented using > > > > err = misc_register(&mce_chrdev_device); > > if (err == -EBUSY) { > > pr_info(...); > > return err; > > } else if (err) { > > pr_err(...); > > return err; > > } > > I didn't want to omit the call to mce_register_decode_chain() in the Xen > case. You should definitely mention that behavior change in the changelog.