diff options
| -rw-r--r-- | src/osmo-bsc/assignment_fsm.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/src/osmo-bsc/assignment_fsm.c b/src/osmo-bsc/assignment_fsm.c index e7dc945af..ded8f0fc3 100644 --- a/src/osmo-bsc/assignment_fsm.c +++ b/src/osmo-bsc/assignment_fsm.c @@ -369,6 +369,34 @@ static int check_for_existing_lchan(struct gsm_subscriber_connection *conn) { struct assignment_request *req = &conn->assignment.req; + /* CHANNEL RE-USE CURRENTLY DISABLED. + * + * This code path would re-use an existing lchan if it already satisfies the mode and rate requested by + * the MSC. + * + * Practical situations where this might arise: + * (a) We were out of SDCCH channels and assigned a TCH channel for signalling, and now that TCH should + * take on the voice stream. + * (b) A call is coming in while another call is ongoing. Then, the user may choose to hang up the + * current call, and continue on the new call instead. In that scenario, the MSC will send us + * another Assignment Command with a different remote RTP address to route RTP to. + * + * In both cases, an existing lchan FSM already in the ACTIVE state needs to set up a voice stream after + * the fact. This is actually not implemented. Hence both scenarios above will end in a voice stream + * failure, aborting the call. + * + * By not re-using the current lchan, we set up a new lchan the same way we always do, and (a) enabling + * voice and (b) switching over to the new caller works. + * + * Hence, disable this lchan re-use until we can re-use an lchan properly. + * + * Test scenario for (b): + * - from A, call B. + * - from C, call B; B rings during ongoing call. + * - in B, pick up the call, choose to drop the old call. + */ + return 0; + if (!conn->lchan) return 0; @@ -493,6 +521,8 @@ void assignment_fsm_start(struct gsm_subscriber_connection *conn, struct gsm_bts /* There may be an already existing lchan, if yes, try to work with * the existing lchan */ if (check_for_existing_lchan(conn)) + /* FIXME: discard the assignment.fi allocated above, and hence properly dispatch the + * GSCON_EV_ASSIGNMENT_END event */ return; /* Try to allocate a new lchan with the preferred codec/rate choice */ |