bogus 0 len IP packet, was: Hang in VOP_LOCK1_APV on 8-STABLE with NFS.

[Ronald Klop]

On Tue, 18 Jan 2011 09:38:04 +0100, <sthaug at nethelp.no> wrote:

>> > So, does anyone have an idea why the IP length field would be set to 0
>> > for these TCP/IP packets?
>> >
>> > Here's some info from Ronald w.r.t. his hardware. (All I can think of  
>> is
>> > that he could try disabling TSO, etc?)
>> >
>> > Thanks in advance for any help with this, rick
>> >
>>
>> It seems that issue came from TSO. Driver will set ip_len and
>> ip_sum field to 0 before passing the TCP segment to controller.
>> The failed length were 4446, 5858, 3034 and 4310 and the total
>> number of such frames are more than 35k within 90 seconds. Since
>> failed length 4310 is continuously repeated I guess there is edge
>> case where em(4) didn't free failed TCP segment for TSO.
>> I remember there was commit to HEAD(r217295) which could be related
>> with this issue.
>
> I'm seeing the same problem with Broadcom NetXtreme (bce) cards:
>
> bce0 at pci0:3:0:0:        class=0x020000 card=0x03421014 chip=0x164c14e4  
> rev=0x12 hdr=0x00
>     vendor     = 'Broadcom Corporation'
>     device     = 'Broadcom NetXtreme II Gigabit Ethernet Adapter  
> (BCM5708)'
>     class      = network
>     subclass   = ethernet
>
> This is with 8.2-PRERELEASE. Turning off TSO (ifconfig bce0 -tso)
> removes the problem.
>
> Steinar Haug, Nethelp consulting, sthaug at nethelp.no
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I tried -tso and -txcsum in various combinations, but it didn't solve the  
problem. I wil look for another brand of network card to try. But this has  
to wait till monday when I'm at the office again.

Ronald.