Re: What is ENXIO – MSI allocation regression in :[Was Re: svn commit: r321714 - in head/sys/dev: mpr mps]

[Scott Long]

> On Jun 5, 2018, at 1:18 AM, Harry Schmalzbauer <freebsd at omnilan.de> wrote:
> 
> Am 05.06.2018 um 00:22 schrieb Scott Long:
>>> On Jun 4, 2018, at 4:51 AM, Harry Schmalzbauer <freebsd at omnilan.de> wrote:
>>> 
>>> Am 01.08.2017 um 11:40 schrieb Harry Schmalzbauer:
>>>> Bezüglich Scott Long's Nachricht vom 31.07.2017 18:56 (localtime):
>>>> 
>>>> …
>>>>>> I'd like to report one I hadn't expected:
>>>>>> 
>>>>>> mps0: <Avago Technologies (LSI) SAS2008> port 0x4000-0x40ff mem 0xc3bc0000-0xc3bc3fff,0xc3b80000-0xc3bbffff irq 19 at device 0.0 on pci7
>>>>>> 
>>>>>> mps0: Firmware: 20.00.04.00, Driver: 21.02.00.00-fbsd
>>>>>> mps0: IOCCapabilities:
>>>>>> 185c<ScsiTaskFull,DiagTrace,SnapBuf,EEDP,TransRetry,IR>
>>>>>> mps0: Cannot allocate INTx interrupt
>>>>>> mps0: mps_iocfacts_allocate failed to setup interrupts
>>>>>> mps0: mps_attach IOC Facts based allocation failed with error 6
>>>>>> panic: resource_list_release: resource entry is not busy
>>>>>> cpuid = 6
>>>>>> KDB: stack backtrace:
>>>>>> #0 0xffffffff805e32d7 at kdb_backtrace+0x67
>>>>>> #1 0xffffffff805a1d26 at vpanic+0x186
>>>>>> #2 0xffffffff805a1b93 at panic+0x43
>>>>>> #3 0xffffffff805d71c6 at resource_list_release+0x1c6
>>>>>> #4 0xffffffff8040fef1 at mps_pci_free+0xe1
>>>>>> #5 0xffffffff8040fa23 at mps_pci_attach+0x1b3
>>>>>> #6 0xffffffff805d6594 at device_attach+0x3a4
>>>>>> #7 0xffffffff805d774d at bus_generic_attach+0x3d
>>>>>> #8 0xffffffff8044ac05 at pci_attach+0xd5
>>>>>> #9 0xffffffff805d6594 at device_attach+0x3a4
>>>>>> #10 0xffffffff805d774d at bus_generic_attach+0x3d
>>>>>> #11 0xffffffff80364761 at acpi_pcib_pci_attach+0xa1
>>>>>> #12 0xffffffff805d6594 at device_attach+0x3a4
>>>>>> #13 0xffffffff805d774d at bus_generic_attach+0x3d
>>>>>> #14 0xffffffff8044ac05 at pci_attach+0xd5
>>>>>> #15 0xffffffff805d6594 at device_attach+0x3a4
>>>>>> #16 0xffffffff805d774d at bus_generic_attach+0x3d
>>>>>> #17 0xffffffff80363e4d at acpi_pcib_acpi_attach+0x42d
>>>>>> Uptime: 1s
>>>> …
>>>> 
>>>>> Fixed in r321799, thanks for the report.
>>>> Fix confiremd; merged together with r321733 (and 321737) to 11.1 and
>>>> panic vanished.
>>> 
>>> Late in the 11.2 phase, I identified this commit as a regression for MSI (non-x) alloctaion.
>>> I have an idea what probably causes the problem here (INTx allocation, although MSI (and MSI-x) capability):
>>> disable_msix is not 0 (I need to disable MSI-x because of ESXi-passthru…).
>>> 
>>> Corresponding lines:
>>> {
>>>         device_t dev;
>>>         int error, msgs;
>>> 
>>>         dev = sc->mps_dev;
>>>         error = 0;
>>>         msgs = 0;
>>> 
>>>         if ((sc->disable_msix == 0) &&
>>>             ((msgs = pci_msix_count(dev)) >= MPS_MSI_COUNT))
>>>                 error = mps_alloc_msix(sc, MPS_MSI_COUNT);
>>>         if ((error != 0) && (sc->disable_msi == 0) &&
>>>             ((msgs = pci_msi_count(dev)) >= MPS_MSI_COUNT))
>>>                 error = mps_alloc_msi(sc, MPS_MSI_COUNT);
>>>         if (error != 0)
>>>                 msgs = 0;
>>> 
>>>         sc->msi_msgs = msgs;
>>>         return (error);
>>> }
>>> 
>>> Before r321714, error was assigned ENXIO, which, if != 0, could help make me understand the problem.
>>> Unfortunately I have no idea what ENXIO means, where it's defined and most important, how to find the place where the declaration/definition happens.  Only joe and vi available here, any hints highly appreciated.
>>> 
>>> I can confirm that MSI allocation works with mps.ko_21.02.00.00-fbsd-r321415 with my ESXi-passthru-non_msi-x setup.
>>> Although the dirver emits no message that an MSI was allocated, like toher drivers do.  That's a cosmetic one though.
>>> But the MSI->INTx regression is a severe one for me, which I'd like to fix myself but I'm missing so many fundamental skills :-(
>>> 
>> Hi Harry,
>> You are correct about the bug.  Please change the line at the top of the function that reads
>> error = 0;
>> to
>> error = ENXIO;
>> Let me know if that fixes the MSI problem for you.
> 
> Hello Scott,
> 
> thanks for your hint.
> Unfortunately I have a lot more problems – the system (11.2-RC1) deadlocks for some soconds with iSCSI load...
> This is far easyer reproducable / heavier impact with mps(4) and INTx allocation than with MSI, but backup runs over night triggered that extreme slowdown although mps(4) was allocating MSI – up to 20 sec locks, where even no terminal update happes.
> All those update ar queued though, so after about 10-20 sedonds, the screen flickers, showing all queued output.
> 
> One symptom is that systat(1) shows 25% intr usage which is one core.
> It's a ZFS machine, so high sys usage is normal, but intr usually is about 10% with GbE traffic.
> Only when the slowdown/lockup happens, intr usage constantly stays at 25%.
> 
> Can't imagine ctld(8) or zfs is causing this, but who knows – I don't at the moment.
> Will have to revert to 11.1 and see if things change, the machine was 10.? before – without such problems.
> 
> BTW, does anybody have a link where I can get info about ENXIO?

ENXIO means that the device is not available.  I use it in the driver to signal when the hardware cannot be accessed.  The manual page for error codes is “man errno"

Scott