kernel assertion failed detatching USB

["John D. Baker" <jdbaker%consolidated.net@localhost>]

While collecting data for kern/52440, I booted a test system with my
live-USB flash drive (9.99.46 from 202002130200Z).  Upon rebooting, the
machine panicked with:

reboot: rebooted by root
[ 147.4887060] syncing disks... done
[ 147.5210129] cd0: detached
[ 147.5584525] atapibus0: detached
[ 147.5887468] atabus1: detached
[ 147.6312528] atabus0: detached
[ 147.6587763] makphy0: detached
[ 147.6987924] msk0: detached
[ 147.7288127] atabus3: detached
[ 147.7688234] atabus2: detached
[ 147.8049328] uhub6: detached
[ 147.8382125] Skipping crash dump on recursive panic
[ 147.8954128] panic: kernel diagnostic assertion "sc->sc_intr_xfer == NULL" failed: file "/x/current/src/sys/dev/usb/uhci.c", line 3928 
[ 148.0399730] cpu0: Begin traceback...
[ 148.0826129] vpanic() at netbsd:vpanic+0x178
[ 148.1304527] kern_assert() at netbsd:kern_assert+0x48
[ 148.1897324] uhci_root_intr_close() at netbsd:uhci_root_intr_close+0x96
[ 148.2698124] usbd_close_pipe() at netbsd:usbd_close_pipe+0xca
[ 148.3301332] uhub_detach() at netbsd:uhub_detach+0xa8
[ 148.3894123] config_detach() at netbsd:config_detach+0xe5
[ 148.4601319] config_detach_all() at netbsd:config_detach_all+0x97
[ 148.5298127] cpu_reboot() at netbsd:cpu_reboot+0x18f
[ 148.5901326] sys_reboot() at netbsd:sys_reboot
[ 148.6400525] sys_reboot() at netbsd:sys_reboot+0x75
[ 148.6993331] syscall() at netbsd:syscall+0x299
[ 148.7492532] --- syscall (number 208) ---
[ 148.7981326] 7d651d24317a:
[ 148.8293325] cpu0: End traceback...
[ 148.8698927] fatal breakpoint trap in supervisor mode
[ 148.9291720] trap type 1 code 0 rip 0xffffffff8021f55d cs 0x8 rflags 0x202 cr2 0x75e474c075b8 ilevel 0 rsp 0xffffc380c1197cd0
[ 149.0633322] curlwp 0xffff925692009a40 pid 11.1 lowest kstack 0xffffc380c11942c0
Stopped in pid 11.1 (reboot) at netbsd:breakpoint+0x5:  leave
db{0}>


It didn't unmount the USB flash drive (sd0a) and it doesn't appear to
have been detached before the panic, so the file system wasn't clean.

Seems to happen only if a umass device is mounted.  Followeing operation
on unmounted umass (fsck), rebooting goes normally.

-- 
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