Looks umb(4) triggers the NET_ASSERT_LOCKED() check in rtable_getsource() when the umb(4) interface comes up (here with kern.splassert=2 to get context). Reproduced with GENERIC.MP from Aug 28 as well with cvs HEAD/if_umb.c rev 1.54.
Something to worry about? OpenBSD 7.3-current (GENERIC.MP) #1357: Mon Aug 28 20:14:09 MDT 2023 dera...@amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP [...] umb0 at uhub0 port 3 configuration 1 interface 0 "FIBOCOM L831-EAU-00" rev 2.00/17.29 addr 2 [...] splassert: rtable_getsource: want 2 have 0 Starting stack trace... rtable_getsource(0,2) at rtable_getsource+0x58 rtm_send(fffffd83b1a817e0,1,0,0) at rtm_send+0xbc umb_add_inet_config(ffff8000017c7000,edf0e72e,18,1f0e72e) at umb_add_inet_config+0x2a8 umb_decode_ip_configuration(ffff8000017c7000,ffff800001ccf230,50) at umb_decode_ip_configuration+0x147 umb_get_response_task(ffff8000017c7000) at umb_get_response_task+0xda usb_task_thread(ffff800022fe0010) at usb_task_thread+0xe5 end trace frame: 0x0, count: 251 End of stack trace. -- jca | PGP : 0x1524E7EE / 5135 92C1 AD36 5293 2BDF DDCC 0DFA 74AE 1524 E7EE