Additional info from CPU 4
ddb{4}> machine ddbcpu 4
Stopped at mtx_enter_try+0x42: movl 0x8(%rdi),%edi
mtx_enter_try(18) at mtx_enter_try+042
mtx_enter(18) at mtx_enter+0x35
taskq_do_barrier(0) at taskq_do_barrier+0x69
bwfm_detach(ffff800000d22000,1) at bwfm_detach+0x5c
bwfm_usb_detach(ffff800000d10d00,ffff800000c2e380) at usbd_detach+0x5a
uhub_port_connect(ffff800000c2e380,2,2a0) at uhub_port_connect+0x82
uhub_explore(ffff800000674f00) at uhub_explore+0xb8
usb_explore(ffff800000674e00) at _usb_explore+0x13c
usb_task_thread(ffff8000466f8a058) at usb_task_thread+0x110
end trace frame: 0x0, count: 4
