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

[David Milburn <dmilburn@redhat.com>]

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) {
>>
>> [    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
>