Cellular Network Infrastructure » Radio Access Network » OsmoPCU

segfault in pdch_ulc_get_node()

ulc is NULL:

Program received signal SIGSEGV, Segmentation fault.
pdch_ulc_get_node (ulc=0x0, fn=fn@entry=55453) at /usr/src/debug/osmo-pcu/0.9.0+gitAUTOINC+c4fe1f97b4-r0.18/git/src/pdch_ul_controller.c:78

Currently looking at an optimised binary running on the sysmoBTS;

Up the stack in handle_ph_data_ind() osmo-bts-sysmo/sysmo_l1_if.c:196

(gdb) p bts->trx[0].pdch[0]->ulc
$41 = (struct pdch_ulc *) 0x0
(gdb) p bts->trx[0].pdch[1]->ulc
$42 = (struct pdch_ulc *) 0x0
(gdb) p bts->trx[0].pdch[2]->ulc
$43 = (struct pdch_ulc *) 0x0
(gdb) p bts->trx[0].pdch[3]->ulc
$44 = (struct pdch_ulc *) 0x0
(gdb) p bts->trx[0].pdch[4]->ulc
$45 = (struct pdch_ulc *) 0x0
(gdb) p bts->trx[0].pdch[5]->ulc
$46 = (struct pdch_ulc *) 0x140a40
(gdb) p bts->trx[0].pdch[6]->ulc
$47 = (struct pdch_ulc *) 0x1418f0
(gdb) p bts->trx[0].pdch[7]->ulc
$48 = (struct pdch_ulc *) 0x1427a0

osmo-bsc Timeslot Config:

   timeslot 0
    phys_chan_config CCCH
    hopping enabled 0
   timeslot 1
    phys_chan_config SDCCH8
    hopping enabled 0
   timeslot 2
    phys_chan_config TCH/H
    hopping enabled 0
   timeslot 3
    phys_chan_config TCH/H
    hopping enabled 0
   timeslot 4
    phys_chan_config TCH/F_TCH/H_PDCH
    hopping enabled 0
   timeslot 5
    phys_chan_config TCH/F_TCH/H_PDCH
    hopping enabled 0
   timeslot 6
    phys_chan_config TCH/F_TCH/H_PDCH
    hopping enabled 0
   timeslot 7
    phys_chan_config PDCH
    hopping enabled 0

I changed timeslot 4 to a TCH/H and then the crash happens again in the same place, only now, ulc for timeslot 5 is NULL!

(gdb) p bts->trx[0].pdch[5]->ulc
$63 = (struct pdch_ulc *) 0x0
(gdb) p bts->trx[0].pdch[6]->ulc
$64 = (struct pdch_ulc *) 0x140a40

to be clear:

#2  0x0001589c in handle_ph_data_ind (fl1h=0x13f430, fl1h=0x13f430, l1p_msg=0x13f620, data_ind=0x13f6e8)
    at /usr/src/debug/osmo-pcu/0.9.0+gitAUTOINC+c4fe1f97b4-r0.18/git/src/osmo-bts-sysmo/sysmo_l1_if.c:196
196    in /usr/src/debug/osmo-pcu/0.9.0+gitAUTOINC+c4fe1f97b4-r0.18/git/src/osmo-bts-sysmo/sysmo_l1_if.c
(gdb) p data_ind->u8Tn
$68 = 5 '\005'