Re: [Bug 84761] New: LSI controller not found when specifying pci=assign-busses

[David Milburn <dmilburn@redhat.com>]

On 09/17/2014 11:35 AM, Andreas Noever wrote:
> On Wed, Sep 17, 2014 at 5:53 PM, David Milburn <dmilburn@redhat.com> wrote:
>> Hi,
>>
>>
>> On 09/17/2014 10:38 AM, Bjorn Helgaas wrote:
>>>
>>> [+cc Andreas, linux-pci, thanks for the bugzilla; please continue
>>> discussion in email]
>>>
>>> On Wed, Sep 17, 2014 at 7:48 AM,  <bugzilla-daemon@bugzilla.kernel.org>
>>> wrote:
>>>>
>>>> https://bugzilla.kernel.org/show_bug.cgi?id=84761
>>>>
>>>>               Bug ID: 84761
>>>>              Summary: LSI controller not found when specifying
>>>>                       pci=assign-busses
>>>>              Product: Drivers
>>>>              Version: 2.5
>>>>       Kernel Version: linux-3.17.0-rc2
>>>>             Hardware: All
>>>>                   OS: Linux
>>>>                 Tree: Mainline
>>>>               Status: NEW
>>>>             Severity: normal
>>>>             Priority: P1
>>>>            Component: PCI
>>>>             Assignee: drivers_pci@kernel-bugs.osdl.org
>>>>             Reporter: dmilburn@redhat.com
>>>>           Regression: No
>>>>
>>>> Created attachment 150651
>>>>     --> https://bugzilla.kernel.org/attachment.cgi?id=150651&action=edit
>>>> Patch to change pcibios_assign_all_busses check in pci_scan_bridge()
>>>>
>>>> When booting with kernel command line option "pci=assign-busses", LSI
>>>> controller
>>>> is no longer found.
>>>>
>>>> 05:00.0 SCSI storage controller: LSI Logic / Symbios Logic SAS1068E
>>>> PCI-Express
>>>> Fusion-MPT SAS (rev 08)
>>>>
>>>> It seems the problem is in pci_scan_bridge (drivers/pci/probe.c):
>>>>
>>>> [    2.542563] PCI_READ_BRIDGE_BASES:
>>>> [    2.545953] PCI_SCAN_BRIDGE:
>>>> [    2.548823] scanning [bus 01-01] behind bridge, pass 0
>>>> [    2.553947] PCI_SCAN_BRIDGE:
>>>> [    2.556818] scanning [bus 05-05] behind bridge, pass 0
>>>> <=========PROBLEM
>>>> [    2.561942] PCI_SCAN_BRIDGE:
>>>> [    2.564812] scanning [bus 06-06] behind bridge, pass 0
>>>> [    2.569936] PCI_SCAN_BRIDGE:
>>>> [    2.572806] scanning [bus 03-03] behind bridge, pass 0
>>>> [    2.577930] PCI_SCAN_BRIDGE:
>>>> [    2.580800] scanning [bus 02-02] behind bridge, pass 0
>>>> [    2.585923] PCI_SCAN_BRIDGE:
>>>> [    2.588793] scanning [bus 04-04] behind bridge, pass 0
>>>>
>>>> If I change the pass 0 check from !pcibios_assign_all_busses() to
>>>> pcibios_assign_all_busses() it finds the LSI controller; however, it
>>>> looks
>>>> like pci_scan_bridge has checked !pcibios_assisng_all_bussses() for a
>>>> very long time.
>>>> (changed code in pci_scan_bridge, causes driver to head down that first
>>>> path)
>>>>     if ((secondary || subordinate) && pcibios_assign_all_busses() &&
>>>>         !is_cardbus && !broken) {
>>>>
> Well, not taking that branch is the main effect of pci=assign-busses.
> Negating the check should be equivalent to not specifying
> pci=assign-busses. Does this actually fix the problem (the SR-IOV
> message)?

Hi,

Yes, I was experimenting going thru the code paths, could there be
a problem where the original code checks to see if the bus already
exists (pci_find_bus...pci_add_new_bus).

The reporter tried the "pci=assign-busses" as a work-around, but
the system didn't boot since the boot drive is on the LSI controller.

>
> Can you attach the full dmesg of the failed boot to the bugzilla
> report. If pci=assign-busses is specified then we only scan during the
> second pass.

Sure, I attached the console output.

Thanks,
David

>
> This is again an LSI card. Looks like they don't take bus changes very well.
>>>> [    2.560225] PCI_SCAN_BRIDGE: secondary 1 subordinate 1 is_cardbus 0
>>>> broken 0
>>>> [    2.567252] PCI_SCAN_BRIDGE: !pcibios_assign_all_busses() 0
>>>>    .
>>>>    .
>>>> [    2.849864] scanning [bus 05-05] behind bridge, pass 0
>>>> <=====SCANNING
>>>> [    2.854988] PCI_SCAN_BRIDGE: CHECKING FOR ASSIGN_ALL_BUSSES
>>>> [    2.860544] PCI_SCAN_BRIDGE: secondary 5 subordinate 5 is_cardbus 0
>>>> broken 0
>>>> [    2.867572] PCI_SCAN_BRIDGE: !pcibios_assign_all_busses() 0
>>>> [    2.873126] PCI_SCAN_BRIDGE: ASSIGN_ALL_BUSSES child           (null)
>>>> [    2.879546] PCI_ADD_NEW_BUS busnr 5:
>>>> [    2.883109] PCI_ALLOC_CHILD_BUS:
>>>> [    2.886327] PCI_SET_BUS_SPEED:
>>>> [    2.889407] PCI_BUS_INSERT_BUSN_RES:
>>>> [    2.892971] PCI_SCAN_CHILD_BUS:
>>>> [    2.896100] PCI_SCAN_CHILD_BUS: scanning bus
>>>> [    2.900357] PCI_SCAN_SLOT:
>>>> [    2.903053] PCI_SCAN_SINGLE_DEVICE:
>>>> [    2.906529] PCI_SCAN_DEVICE: devfn 0
>>>> [    2.910093] PCI_BUS_READ_DEV_VENDOR_ID: devfn 0
>>>> [    2.914608] PCI_ALLOC_DEV:
>>>> [    2.917305] PCI_SETUP_DEVICE:
>>>> [    2.920262] SET_PCIE_PORT_TYPE:       =====DEVICE FOUND BELOW=====
>>>> [    2.923399] pci 0000:05:00.0: [1000:0058] type 00 class 0x010000
>>>> [    2.923401] [1000:0058] type 00 class 0x010000
>>>> [    2.927841] pci 0000:05:00.0: reg 0x10: [io  0xec00-0xecff]
>>>> [    2.927852] pci 0000:05:00.0: reg 0x14: [mem 0xde2ec000-0xde2effff
>>>> 64bit]
>>>> [    2.927863] pci 0000:05:00.0: reg 0x1c: [mem 0xde2f0000-0xde2fffff
>>>> 64bit]
>>>> [    2.927877] pci 0000:05:00.0: reg 0x30: [mem 0xde100000-0xde1fffff
>>>> pref]
>>>> [    2.927879] PCI_DEVICE_ADD:
>>>
>>>
>>> Tangent: why do you need "pci=assign-busses"?  If that's necessary to
>>> make some device work, I think that's a different bug in itself.
>>
>>
>> User reported trying this as
>>
>> As a workaround for
>> igb 0000:06:00.1: SR-IOV: bus number out of range
>>>
>>> Is this a regression?
>>
>>
>> It was reproduced on RHEL6.1, so I don't think so. So far I have
>> reproduced on upstream linux-3.17.0-rc2 and -rc5.
>>
>>>
>>> Can you attach complete dmesg logs with and without "pci=assign-busses"?
>>
>>
>> Ok, I will attach the logs to the BZ.
>>
>>>
>>> We have a couple patches that are candidates for reversion before
>>> v3.17 because of similar issues (I think they're good patches, but we
>>> may need some additional work to fix some other problems they
>>> exposed).  If you want to try them, they're here:
>>>
>>> https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/log/?h=pci/reverts
>>
>>
>> Ok, I will give them a try.
>>
>> Thanks,
>> David
>>
>>>
>>> Bjorn
>>>
>>