kern/142019: em needs "ifconfig em0 down up" when link was gone

[Andre Albsmeier]

>Number:         142019
>Category:       kern
>Synopsis:       em needs "ifconfig em0 down up" when link was gone
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Dec 25 18:30:01 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Andre Albsmeier
>Release:        FreeBSD 7.2-STABLE i386
>Organization:
>Environment:

System: FreeBSD 7.2-STABLE #0: Sat Nov 28 12:28:42 CET 2009 

em0: <Intel(R) PRO/1000 Network Connection 6.9.6> port 0xcf00-0xcf1f mem 0xfd7e0000-0xfd7fffff irq 16 at device 0.0 on pci2
em0: Using MSI interrupt

em0 at pci0:2:0:0: class=0x020000 card=0x64101462 chip=0x109a8086 rev=0x00 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = 'Intel PRO/1000 PL Network Adaptor (82573L)'
    class      = network
    subclass   = ethernet

>Description:

The em0 interface mentioned above is connected to another 100MBit
Ethernet device through a cross cable. Everything works until
this other device is powered down and up again. In this case
one can't talk to this device anymore:

gate:~>ping 192.168.128.66
PING 192.168.128.66 (192.168.128.66): 56 data bytes
ping: sendto: No buffer space available
ping: sendto: No buffer space available
ping: sendto: No buffer space available
...

After running "ifconfig em0 down up" on the FreeBSD box all is
well (pinging and transferring files) until the other device
has been  powered down and up again.

The very same hardware didn't show this problem in 6-STABLE
so I assume something has changed in the em driver.

>How-To-Repeat:

See above. I tried with a satellite dish receiver and another
fxp-based machine as the other device.

>Fix:

Unknown, possibly a MFC of the em driver from 8-STABLE
might be enough, see:
 
http://lists.freebsd.org/pipermail/freebsd-stable/2009-November/052887.html

>Release-Note:
>Audit-Trail:
>Unformatted: