linux-kernel - Re: Linux IPMI subsystem hang

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Message-ID: <87vc8s7ap4.fsf@alice.fifthhorseman.net>
Date:	Fri, 15 Mar 2013 14:57:27 -0400
From:	Daniel Kahn Gillmor <dkg@...thhorseman.net>
To:	Corey Minyard <minyard@...sta.com>,
	Corey Minyard <minyard@....org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Linux IPMI subsystem hang

On Tue 2013-03-12 22:23:37 -0400, Daniel Kahn Gillmor wrote:

> I am working with a Lenovo ThinkCentre M78, model 4865-A14, and it seems
> to have trouble with the IPMI subsystem.
>
> udev seems to hang for about 3 minutes at startup, ultimately failing
> with the following messages:
>
> udevd[416]: worker [495] unexpectedly returned with status 0x0100
> udevd[416]: worker [495] failed while handling '/devices/pci0000:00/0000:00:15.2/0000:03:00.3'
>
> This hang happens whether i'm running linux kernel 3.2 or 3.8, using
> either x86 or x86_64 kernels.

trying with udev 175-7.1 (from debian unstable) and kernel 3.2, i see
that the failure message is:

udevd[548]: timeout: killing '/sbin/modprobe -b pci:v000010ECd0000816Csv000017AAsd00003089bc0Csc07i01' [623]

and:

[    5.650931] ipmi message handler version 39.2
[    5.916958] IPMI System Interface driver.
[    5.921153] ipmi_si 0000:03:00.3: probing via PCI
[    5.925851] ipmi_si 0000:03:00.3: [io  0xe000-0xe0ff] regsize 1 spacing 1 irq 17
[    5.933727] ipmi_si: Adding PCI-specified kcs state machine
[    5.939554] ipmi_si: Trying PCI-specified kcs state machine at i/o address 0xe000, slave address 0x0, irq 17
[  406.916061] ipmi_si: There appears to be no BMC at this location

with kernel 3.8, the last line ("There appears to be no BMC at this
location") isn't emitted, but the delay/hang with modprobe still
happens.

I think the first alias in ipmi_si.ko is what is causing this to be triggered:

0 krazy:~# modinfo ipmi_si | grep ^alias
alias:          pci:v*d*sv*sd*bc0Csc07i*
alias:          pci:v0000103Cd0000121Asv*sd*bc*sc*i*
0 krazy:~# 

since the bc0Csc07 matches the [0c07] identifier from lspci:

> 03:00.3 IPMI SMIC interface [0c07]: Realtek Semiconductor Co., Ltd. Device [10ec:816c] (rev 01) (prog-if 01)

It seems like there are four plausible cases:

 0) this is actually an IPMI device, but the hardware is broken.

 1) this is an IPMI device, but it does not implement some part of the
    IPMI spec that ipmi_si.ko expects to be implemented, and ipmi_si.ko
    cannot detect this cleanly.

 2) this device is not an IPMI device at all, and is mislabeled in its
    PCI identifiers somehow.

 3) this device is not an IPMI device at all, it is properly labeled,
    and the module's internal aliasing (and lspci's index?) is
    overgeneral and misidentifies the device.

How can i distinguish between these cases?

> I am not subscribed to LKML, so please CC me on any replies.

Regards,

        --dkg

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