From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [PATCH 25/30] ACPI / hotplug / PCI: Check for new devices on enabled slots Date: Thu, 05 Sep 2013 08:21:41 -0600 Message-ID: <1378390901.3246.233.camel@ul30vt.home> References: <26431283.HJCKsss0rt@vostro.rjw.lan> <1378352279.3246.183.camel@ul30vt.home> <1378353962.3246.192.camel@ul30vt.home> <3752304.TvOhsce0U1@vostro.rjw.lan> <1378387184.3246.227.camel@ul30vt.home> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:6946 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752250Ab3IEOV5 (ORCPT ); Thu, 5 Sep 2013 10:21:57 -0400 In-Reply-To: <1378387184.3246.227.camel@ul30vt.home> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" Cc: ACPI Devel Maling List , Bjorn Helgaas , LKML , Linux PCI , Yinghai Lu , Jiang Liu , Mika Westerberg , "Kirill A. Shutemov" On Thu, 2013-09-05 at 07:19 -0600, Alex Williamson wrote: > On Thu, 2013-09-05 at 13:54 +0200, Rafael J. Wysocki wrote: > > On Wednesday, September 04, 2013 10:06:02 PM Alex Williamson wrote: > > > On Wed, 2013-09-04 at 21:37 -0600, Alex Williamson wrote: > > > > On Thu, 2013-09-05 at 01:35 +0200, Rafael J. Wysocki wrote: > > > > > On Wednesday, September 04, 2013 05:12:14 PM Alex Williamson wrote: > > > > > > On Thu, 2013-09-05 at 00:54 +0200, Rafael J. Wysocki wrote: > > > > > > > On Wednesday, September 04, 2013 02:36:34 PM Alex Williamson wrote: > > > > > > > > On Thu, 2013-07-18 at 01:32 +0200, Rafael J. Wysocki wrote: > > > > > > > > > From: Rafael J. Wysocki > > > > > > > > > > > > > > > > > > The current implementation of acpiphp_check_bridge() is pretty dumb: > > > > > > > > > - It enables a slot if it's not enabled and the slot status is > > > > > > > > > ACPI_STA_ALL. > > > > > > > > > - It disables a slot if it's enabled and the slot status is not > > > > > > > > > ACPI_STA_ALL. > > > > > > > > > > > > > > > > > > This behavior is not sufficient to handle the Thunderbolt daisy > > > > > > > > > chaining case properly, however, because in that case the bus > > > > > > > > > behind the already enabled slot needs to be rescanned for new > > > > > > > > > devices. > > > > > > > > > > > > > > > > > > For this reason, modify acpiphp_check_bridge() so that slots are > > > > > > > > > disabled and stopped if they are not in the ACPI_STA_ALL state. > > > > > > > > > > > > > > > > > > For slots in the ACPI_STA_ALL state, devices behind them that don't > > > > > > > > > respond are trimmed using a new function, trim_stale_devices(), > > > > > > > > > introduced specifically for this purpose. That function walks > > > > > > > > > the given bus and checks each device on it. If the device doesn't > > > > > > > > > respond, it is assumed to be gone and is removed. > > > > > > > > > > > > > > > > > > Once all of the stale devices directy behind the slot have been > > > > > > > > > removed, acpiphp_check_bridge() will start looking for new devices > > > > > > > > > that might have appeared on the given bus. It will do that even if > > > > > > > > > the slot is already enabled (SLOT_ENABLED is set for it). > > > > > > > > > > > > > > > > > > In addition to that, make the bus check notification ignore > > > > > > > > > SLOT_ENABLED and go for enable_device() directly if bridge is NULL, > > > > > > > > > so that devices behind the slot are re-enumerated in that case too. > > > > > > > > > > > > > > > > > > This change is based on earlier patches from Kirill A Shutemov > > > > > > > > > and Mika Westerberg. > > > > > > > > > > > > > > > > > > Signed-off-by: Rafael J. Wysocki > > > > > > > > > Tested-by: Mika Westerberg > > > > > > > > > --- > > > > > > > > > > > > > > > > FYI, git bisect landed on this patch as the cause of my serial console > > > > > > > > dying on current upstream. Further debugging to come... Thanks, > > > > > > > > > > > > > > Well, sorry about that. > > > > > > > > > > > > > > What exactly do you mean by "dying"? > > > > > > > > > > > > Sorry, I was hoping to have more details quickly, but it's been a pain > > > > > > to debug. By dying I mean serial console output suddenly stops during > > > > > > kernel boot and nothing more comes out of it until after the system is > > > > > > rebooted. The problem happens when acpiphp_check_bridge() calls > > > > > > enable_slot(). The serial console dies somewhere down in > > > > > > acpiphp_bus_trim(). I think this is happening on the 00:1f ISA bridge, > > > > > > so there's a good chance the serial ports are described as somewhere > > > > > > under there. > > > > > > > > > > Can you please check if that is the acpiphp_bus_trim() called by > > > > > acpiphp_bus_add() or the other one called from trim_stale_devices()? > > > > > > > > > > Just add a dump_stack() or WARN_ON(1) to trim_stale_devices() next to > > > > > the acpiphp_bus_trim() call and see if that triggers. I *think* it's the one > > > > > in acpiphp_bus_add(), but it won't hurt to verify that. > > > > > > > > Here's the call path: > > > > > > > > [ 16.120824] [] dump_stack+0x55/0x76 > > > > [ 16.125979] [] enable_slot+0x4ee/0x5e0 > > > > [ 16.131396] [] ? trim_stale_devices+0x5b/0xf0 > > > > [ 16.137420] [] acpiphp_check_bridge+0xd5/0x110 > > > > [ 16.143531] [] hotplug_event+0x16b/0x260 > > > > [ 16.149115] [] ? process_one_work+0x189/0x540 > > > > [ 16.155136] [] hotplug_event_work+0x30/0x70 > > > > [ 16.160978] [] process_one_work+0x1eb/0x540 > > > > [ 16.166819] [] ? process_one_work+0x189/0x540 > > > > [ 16.172836] [] worker_thread+0x11c/0x370 > > > > [ 16.178426] [] ? rescuer_thread+0x350/0x350 > > > > [ 16.184276] [] kthread+0xea/0xf0 > > > > [ 16.189165] [] ? kthread_create_on_node+0x160/0x160 > > > > [ 16.195700] [] ret_from_fork+0x7c/0xb0 > > > > [ 16.201109] [] ? kthread_create_on_node+0x160/0x160 > > > > > > > > The actual death of the serial console occurs in acpi_device_set_power() > > > > called from: > > > > > > > > enable_slot() > > > > acpiphp_bus_add() > > > > acpiphp_bus_trim() > > > > acpi_bus_trim() > > > > acpi_walk_namespace() > > > > acpi_bus_remove() > > > > acpi_device_unregister() > > > > acpi_device_set_power() > > > > > > > > I can't seem to get a path from the acpi devices in question there, so I > > > > have no idea what's getting trimmed here. It worries me quite a bit by > > > > introducing this trimming that apparently wasn't happening before > > > > though. Thanks, > > > > > > As suspected, the pnp.bus_id/id of the last device before the serial > > > console dies is COM1/PNP0501. I also see all of these being trimmed > > > out: > > > > > > MBRD/PNP0C02 > > > DMAC/PNP0200 > > > MATH/PNP0C04 > > > PIC/PNP0000 > > > HPET/PNP0103 > > > RTC/PNP0B00 > > > SPKR/PNP0800 > > > TIME/PNP0100 > > > LNK{A-H}/PNP0C0F > > > > > > This seems like a bad idea. I forgot to mention, the original > > > hotplug_event is called with a device check on \_SB_.PCI0.PEX2. The box > > > where I'm seeing this is a pretty generic X58 based Nehalem workstation > > > (Lenovo S20). > > > > Thanks for the info! > > > > The acpiphp_bus_trim() in acpiphp_bus_add() is a leftover and a bad one. > > I don't think it's actually necessary, at least Thunderbolt works without > > it just fine on my Aspire S5. > > > > The patch below should help, can you please test it? > > > > Rafael > > > > --- > > From: Rafael J. Wysocki > > Subject: ACPI / hotplug / PCI: Don't trim devices before scanning the namespace > > > > In acpiphp_bus_add() we first remove device objects corresponding to > > the given handle and the ACPI namespace branch below it which are > > then re-created by acpi_bus_scan(). This used to be done to clean > > up after surprise removals, but now we do the cleanup through > > trim_stale_devices() which checks if the devices in question are > > actually gone before removing them, so the device hierarchy trimming > > in acpiphp_bus_add() is not necessary any more and, moreover, it may > > lead to problems if it removes device objects corresponding to > > devices that are actually present. > > > > Reported-by: Alex Williamson > > Signed-off-by: Rafael J. Wysocki > > --- > > drivers/pci/hotplug/acpiphp_glue.c | 1 - > > 1 file changed, 1 deletion(-) > > > > Index: linux-pm/drivers/pci/hotplug/acpiphp_glue.c > > =================================================================== > > --- linux-pm.orig/drivers/pci/hotplug/acpiphp_glue.c > > +++ linux-pm/drivers/pci/hotplug/acpiphp_glue.c > > @@ -487,7 +487,6 @@ static void acpiphp_bus_add(acpi_handle > > { > > struct acpi_device *adev = NULL; > > > > - acpiphp_bus_trim(handle); > > acpi_bus_scan(handle); > > acpi_bus_get_device(handle, &adev); > > if (adev) > > > > > > It boots again and the console works, but I see screens and screens of > messages like this: > > [ 18.288122] pci 0000:00:00.0: no hotplug settings from platform > [ 18.288127] pcieport 0000:00:01.0: no hotplug settings from platform > [ 18.288142] pci 0000:01:00.0: no hotplug settings from platform > [ 18.288157] pci 0000:01:00.1: no hotplug settings from platform > [ 18.288162] pcieport 0000:00:03.0: no hotplug settings from platform > [ 18.288176] pci 0000:02:00.0: no hotplug settings from platform > [ 18.288190] pci 0000:02:00.1: no hotplug settings from platform > [ 18.288195] pcieport 0000:00:07.0: no hotplug settings from platform > [ 18.288209] pci 0000:03:00.0: no hotplug settings from platform > [ 18.288224] pci 0000:03:00.1: no hotplug settings from platform > [ 18.288228] pci 0000:00:14.0: no hotplug settings from platform > [ 18.288233] pci 0000:00:14.1: no hotplug settings from platform > [ 18.288237] pci 0000:00:14.2: no hotplug settings from platform > [ 18.288242] pci 0000:00:16.0: no hotplug settings from platform > [ 18.288247] pci 0000:00:16.1: no hotplug settings from platform > [ 18.288251] pci 0000:00:16.2: no hotplug settings from platform > [ 18.288256] pci 0000:00:16.3: no hotplug settings from platform > [ 18.288260] pci 0000:00:16.4: no hotplug settings from platform > [ 18.288265] pci 0000:00:16.5: no hotplug settings from platform > [ 18.288269] pci 0000:00:16.6: no hotplug settings from platform > [ 18.288274] pci 0000:00:16.7: no hotplug settings from platform > [ 18.288278] pci 0000:00:1a.0: no hotplug settings from platform > [ 18.288279] pci 0000:00:1a.0: using default PCI settings > [ 18.288292] pci 0000:00:1a.1: no hotplug settings from platform > [ 18.288293] pci 0000:00:1a.1: using default PCI settings > [ 18.288307] ehci-pci 0000:00:1a.7: no hotplug settings from platform > [ 18.288308] ehci-pci 0000:00:1a.7: using default PCI settings > [ 18.288322] pci 0000:00:1b.0: no hotplug settings from platform > [ 18.288327] pcieport 0000:00:1c.0: no hotplug settings from platform > [ 18.288332] pcieport 0000:00:1c.4: no hotplug settings from platform > [ 18.288344] pci 0000:05:00.0: no hotplug settings from platform > [ 18.288349] pci 0000:00:1d.0: no hotplug settings from platform > [ 18.288350] pci 0000:00:1d.0: using default PCI settings > [ 18.288360] pci 0000:00:1d.1: no hotplug settings from platform > [ 18.288361] pci 0000:00:1d.1: using default PCI settings > [ 18.288374] pci 0000:00:1d.2: no hotplug settings from platform > [ 18.288374] pci 0000:00:1d.2: using default PCI settings > [ 18.288387] pci 0000:00:1d.3: no hotplug settings from platform > [ 18.288387] pci 0000:00:1d.3: using default PCI settings > > The boot is noticeably slower. What's going to happen on systems that > actually have a significant I/O topology vs my little workstation? Just to give you an idea: CONFIG_HOTPLUG_PCI_ACPI=y $ dmesg | wc 5697 49935 384368 $ dmesg | tail --lines=1 [ 53.137123] Ebtables v2.0 registered -- vs -- # CONFIG_HOTPLUG_PCI_ACPI is not set $ dmesg | wc 1053 9176 71652 $dmesg | tail --lines=1 [ 28.917220] Ebtables v2.0 registered So it spews out 5x more output with acpiphp enabled and takes and extra 24s to boot (nearly 2x). Not good. Thanks, Alex