kern/50442: bge0 locks up with tso4

[sd4dfg2%hotmail.com@localhost]

>Number:         50442
>Category:       kern
>Synopsis:       bge0 locks up with tso4
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Nov 17 20:20:00 +0000 2015
>Originator:     Rob
>Release:        7.0_STABLE
>Organization:
>Environment:
>Description:
If I enable tso4 on my gigabit bge0 interface it hangs when I send a moderate amount of traffic.

bge0 at pci6 dev 0 function 0: Broadcom BCM5720 Gigabit Ethernet
bge0: interrupting at ioapic0 pin 16
bge0: APE firmware NCSI 1.2.33.0
bge0: HW config 002b1594, 00006014, 0000aa08, 00000000 00000000
bge0: ASIC BCM5720 A0 (0x5720000), Ethernet address f8:bc:12:51:1b:86
bge0: setting short Tx thresholds
brgphy0 at bge0 phy 1: BCM5720C 1000BASE-T media interface, rev. 0

Sometimes it logs this:
bge0: watchdog timeout -- resetting
bge0: block failed to stop: reg 0xc00, bit 0x00000002

Sometimes other sessions aren't hung and I can run "ifconfig -tso4" (or login to the console and run it) to clear the hung sessions.
>How-To-Repeat:
I've only done very limited testing.  If you feel it's a hardware issue and not software, go ahead and close the ticket.

ifconfig bge0 tso4
find /

>Fix: