From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933445AbcFOU04 (ORCPT ); Wed, 15 Jun 2016 16:26:56 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:34952 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932612AbcFOU0u (ORCPT ); Wed, 15 Jun 2016 16:26:50 -0400 X-IBM-Helo: d03dlp01.boulder.ibm.com X-IBM-MailFrom: gkurz@linux.vnet.ibm.com X-IBM-RcptTo: mpe@ellerman.id.au;david@gibson.dropbear.id.au;benh@kernel.crashing.org;linuxppc-dev@lists.ozlabs.org;qemu-ppc@nongnu.org;paulus@samba.org;linux-kernel@vger.kernel.org Subject: [PATCH v2] powerpc/pseries: start rtasd before PCI probing From: Greg Kurz To: Michael Ellerman Cc: Benjamin Herrenschmidt , linux-kernel@vger.kernel.org, qemu-ppc@nongnu.org, Paul Mackerras , linuxppc-dev@lists.ozlabs.org, David Gibson Date: Wed, 15 Jun 2016 22:26:41 +0200 User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16061520-0028-0000-0000-000004F6A811 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16061520-0029-0000-0000-00002CB1D02E Message-Id: <146602104462.23192.4267928292361711364.stgit@bahia.lan> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-06-15_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1606150217 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A strange behaviour is observed when comparing PCI hotplug in QEMU, between x86 and pseries. If you consider the following steps: - start a VM - add a PCI device via the QEMU monitor before the rtasd has started (for example starting the VM in paused state, or hotplug during FW or boot loader) - resume the VM execution The x86 kernel detects the PCI device, but the pseries one does not. This happens because the rtasd kernel worker is currently started under device_initcall, while PCI probing happens earlier under subsys_initcall. As a consequence, if we have a pending RTAS event at boot time, a message is printed and the event is dropped. This patch moves all the initialization of rtasd to arch_initcall, which is run before subsys_call: this way, logging_enabled is true when the RTAS event pops up and it is not lost anymore. The proc fs bits stay at device_initcall because they cannot be run before fs_initcall. Signed-off-by: Greg Kurz --- v2: - avoid behaviour change: don't create the proc entry if early init failed Michael, This was also tested under PowerVM: it doesn't fix anything there because the HMC tells it won't honor DLPAR features as long as the RMC isn't here, which happens later in the boot sequence. It hence seems impossible to have a pending RTAS event at boot time. It doesn't seem to break anything either, the kernel boots and hotplug works okay once the RMC is up. Cheers. -- Greg --- arch/powerpc/kernel/rtasd.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c index e864b7c5884e..a26a02006576 100644 --- a/arch/powerpc/kernel/rtasd.c +++ b/arch/powerpc/kernel/rtasd.c @@ -526,10 +526,8 @@ void rtas_cancel_event_scan(void) } EXPORT_SYMBOL_GPL(rtas_cancel_event_scan); -static int __init rtas_init(void) +static int __init rtas_event_scan_init(void) { - struct proc_dir_entry *entry; - if (!machine_is(pseries) && !machine_is(chrp)) return 0; @@ -562,13 +560,27 @@ static int __init rtas_init(void) return -ENOMEM; } + start_event_scan(); + + return 0; +} +arch_initcall(rtas_event_scan_init); + +static int __init rtas_init(void) +{ + struct proc_dir_entry *entry; + + if (!machine_is(pseries) && !machine_is(chrp)) + return 0; + + if (!rtas_log_buf) + return -ENODEV; + entry = proc_create("powerpc/rtas/error_log", S_IRUSR, NULL, &proc_rtas_log_operations); if (!entry) printk(KERN_ERR "Failed to create error_log proc entry\n"); - start_event_scan(); - return 0; } __initcall(rtas_init);