kern/53265: panic in bnx_detach() on shutdown

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         53265
>Category:       kern
>Synopsis:       panic in bnx_detach() on shutdown
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun May 06 12:05:00 +0000 2018
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date 2018.05.04.14.15.41
>Organization:

>Environment:
System: NetBSD 
Architecture: x86_64
Machine: amd64
>Description:

Seen on the serial console shutting down an 8-core amd64 machine
running a fresh -current:

[ 63426.6135600] syncing disks... done
[ 63428.0241184] cd0: detached
[ 63428.0608678] brgphy3: detached
[ 63428.0983665] brgphy2: detached
[ 63428.1358664] brgphy1: detached
[ 63428.1733649] brgphy0: detached
[ 63428.2108644] atapibus0: detached
[ 63428.2442055] uhub5: detached
[ 63428.2842215] uhub4: detached
[ 63428.3142328] uhub2: detached
[ 63428.3542487] uhub1: detached
[ 63428.3842605] uhub0: detached
[ 63428.4242764] com1: detached
[ 63428.4642922] bnx3: detached
[ 63428.5043087] bnx2: detached
[ 63428.5443239] Skipping crash dump on recursive panic
[ 63428.5943436] panic: kernel diagnostic assertion "c->c_cpu->cc_lwp == curlwp || c->c_cpu->cc_active != c" failed: file "/tmp/bracket/build/2018.05.04.14.15\
.41-amd64-debug-baremetal/src/sys/kern/kern_timeout.c", line 318
[ 63428.8344384] cpu7: Begin traceback...
[ 63428.8744542] vpanic() at netbsd:vpanic+0x16f
[ 63428.9344780] ch_voltag_convert_in() at netbsd:ch_voltag_convert_in
[ 63429.0045057] callout_destroy() at netbsd:callout_destroy+0x75
[ 63429.0745334] bnx_detach() at netbsd:bnx_detach+0xbb
[ 63429.1345572] config_detach() at netbsd:config_detach+0x121
[ 63429.2045849] config_detach_all() at netbsd:config_detach_all+0x97
[ 63429.2746126] cpu_reboot() at netbsd:cpu_reboot+0x19a
[ 63429.3346364] sys_reboot() at netbsd:sys_reboot+0x85
[ 63429.3946602] syscall() at netbsd:syscall+0x208
[ 63429.4446800] --- syscall (number 208) ---
[ 63429.4946998] 74ed2443ebda:
[ 63429.5347157] cpu7: End traceback...
[ 63429.5847356] rebooting...

No harm done, but it's a bug nonetheless...

>How-To-Repeat:

Only happened once so far.

>Fix: