kern/52771: vioif(4) panics caused by ifconfig down/up

[uebayasi%gmail.com@localhost]

>Number:         52771
>Category:       kern
>Synopsis:       vioif(4) panics caused by ifconfig down/up
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Nov 29 06:45:00 +0000 2017
>Originator:     Masao Uebayashi
>Release:        NetBSD 8.0_BETA
>Organization:
Earth
>Environment:
NetBSD xxx.xxx.xxx 8.0_BETA NetBSD 8.0_BETA (GENERIC.201711211410Z) amd64
>Description:
I have been doing `ifconfig vioif0 down; ifconfig vioif0 up` periodically to work around vioif(4) stall (at least on netbsd-7).  (Not sure this is still the case on netbsd-8.)

I've got 2 panics after installed NetBSD 8.0_BETA.  Those two have exact same back traces:

crash> bt
_KERNEL_OPT_NARCNET() at 0
?() at fffffe80035d8018
vpanic() at vpanic+0x149
snprintf() at snprintf
bus_dmamap_create() at bus_dmamap_create
vioif_rx_deq_locked() at vioif_rx_deq_locked+0x148
vioif_stop() at vioif_stop+0xa1
vioif_init() at vioif_init+0x1e
vioif_ioctl() at vioif_ioctl+0x2f
doifioctl() at doifioctl+0x77b
soo_ioctl() at soo_ioctl+0x2b5
sys_ioctl() at sys_ioctl+0x101
syscall() at syscall+0x1d8
--- syscall (number 54) ---
72687e8feeea:
crash> 

>How-To-Repeat:
Repeat `ifconfig vioifN down; ifconfig vioifN up` on an active system.
>Fix: