lchan release may stall indefinitely
When the MSC hard-releases the SCCP connection, we terminate the
bsc_subscr_conn_fsm, which calls
lchan_release(conn->lchan, 0, RSL_REL_LOCAL_END); from the fsm cleanup call-back.
That in turn causes a RLL_REL_REQ to be transmitted. However, if the MS never responds to that (out of reach, power-cycle, ...) there appears to be no timer running which would proceed with sending an
RSL RF CHAN REL to actually release the channel.
This is currently triggered by
TC_bssap_rlsd_does_not_cause_bssmap_reset involuntarily, as it tries to allocate 8 SDCCH.
Attaching a pcap file.
I'll add a dedicated test for this behavior.
New test provoking this problem is in https://gerrit.osmocom.org/#/c/osmo-ttcn3-hacks/+/9548
Assigned to neels as his existing work on lchan FSM will likely solve this bug.