kern/53598: assertion failure in usb detach

[martin%NetBSD.org@localhost]

>Number:         53598
>Category:       kern
>Synopsis:       assertion failure in usb detach
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Sep 12 11:40:00 +0000 2018
>Originator:     Martin Husemann
>Release:        NetBSD 8.99.25
>Organization:
The NetBSD Foundation, Inc.
>Environment:
(not this actual kernel...)
System: NetBSD seven-days-to-the-wolves.aprisoft.de 8.99.25 NetBSD 8.99.25 (GENERIC) #236: Tue Sep 4 08:48:16 CEST 2018 martin%seven-days-to-the-wolves.aprisoft.de@localhost:/work/src/sys/arch/amd64/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:

Trying to reboot a GENERIC kernel from the 201809111830Z daily build
reproducable crashes for me like this (manual transscript):

panic: kernel diagnostic assertion "cv_is_valid(cv)" failed: file ...kern/kern_condvar.c line 151
vpanic
ch_voltag_convert_in() at netbsd:ch_voltag_convert_in
cv_destroy() at netbsd:cv_destroy+0x55
usb_detach() at netbsd:usb_detach+0xf9
...

>How-To-Repeat:
s/a

>Fix:
n/a