kern/53233: one-off kernel panic while connecting a urtwn device

[coypu%sdf.org@localhost]

>Number:         53233
>Category:       kern
>Synopsis:       one-off kernel panic while connecting a urtwn device
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Apr 29 19:50:00 +0000 2018
>Originator:     coypu
>Release:        NetBSD 8.99.14
>Organization:
>Environment:
NetBSD planets 8.99.14 NetBSD 8.99.14 (GENERIC) #0: Mon Mar 26 06:12:37 IDT 2018  fly@planets:/home/fly/obj/sys/arch/amd64/compile/GENERIC amd64

>Description:
connect urtwn device. Win hotplug lottery.

urtwn0 at uhub3 port 1
urtwn0: Realtek (0x7392) 802.11n WLAN Adapter (0x7811), rev 2.00/2.00, addr 3
urtwn0: MAC/BB RTL8188CUS, RF 6052 1T1R, address 74:da:38:5b:6c:6c
urtwn0: 1 rx pipe, 2 tx pipes
urtwn0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
urtwn0: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
fatal page fault in supervisor mode
trap type 6 code 0 rip 0xffffffff80976a36 cs 0x8 rflags 0x10286 cr2 0x8 ilevel 0x6 rsp 0xffff800064f6ae10
curlwp 0xffffe40137a09440 pid 0.6 lowest kstack 0xffff800064f672c0
panic: trap
cpu0: Begin traceback...
vpanic() at netbsd:vpanic+0x140
snprintf() at netbsd:snprintf
startlwp() at netbsd:startlwp
alltraps() at netbsd:alltraps+0xb7
mutex_vector_enter() at netbsd:mutex_vector_enter+0xc6
ieee80211_find_rxnode() at netbsd:ieee80211_find_rxnode+0x3e
urtwn_rxeof() at netbsd:urtwn_rxeof+0x29a
usb_transfer_complete() at netbsd:usb_transfer_complete+0x146
ehci_softintr() at netbsd:ehci_softintr+0x19c
usb_soft_intr() at netbsd:usb_soft_intr+0x1f
softint_dispatch() at netbsd:softint_dispatch+0xd9
DDB lost frame for netbsd:Xsoftintr+0x4f, trying 0xffff800064f6b0f0
Xsoftintr() at netbsd:Xsoftintr+0x4f
--- interrupt ---
fbe4ef6ffafe10dc:
cpu0: End traceback...

dumping to dev 0,1 (offset=1896, size=1013425):
dump succeeded

>How-To-Repeat:

>Fix:
Don't expect netbsd to support hotplug.