tbf: Remove TBF chaining (m_new_tbf and m_old_tbf)

Currently a new TBF is chained to an existing older one, either of
the other direction (active or releasing) or of the same direction
(releasing). This does not work properly work if and uplink and a
downlink TBF are being established at the same time while an old TBF
is being released. In that case, one of them is thrown away and the
pending procedure is cancelled.

The chaining is no longer necessary since the GprsMs objects have
been introduced which keep track of the active TBFs.

This commit removes the TBF members m_new_tbf and m_old_tbf and the
related methods and code paths.

Note that a new TBF can replace an older TBF entry of the same
direction within an MS object when it is associated with an MS (e.g.
by TLLI or because it is assigned via another, already associated
TBF). In that case, the old TBF is no longer associated with an MS
object.

Ticket: #1674
Sponsored-by: On-Waves ehf

1 files changed, 8 insertions, 11 deletions

diff --git a/src/bts.cpp b/src/bts.cpp
index f1339774..c7daf8e6 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -482,7 +482,6 @@ void BTS::trigger_dl_ass(
 			"PACCH, because %s exists\n", tbf_name(old_tbf));
 		old_tbf->dl_ass_state = GPRS_RLCMAC_DL_ASS_SEND_ASS;
 
-		old_tbf->set_new_tbf(dl_tbf);
 		old_tbf->was_releasing = old_tbf->state_is(GPRS_RLCMAC_WAIT_RELEASE);
 
 		/* use TA from old TBF */
@@ -498,7 +497,6 @@ void BTS::trigger_dl_ass(
 		/* change state */
 		dl_tbf->set_state(GPRS_RLCMAC_ASSIGN);
 		dl_tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_CCCH);
-		dl_tbf->set_new_tbf(dl_tbf);
 		/* send immediate assignment */
 		dl_tbf->bts->snd_dl_ass(dl_tbf, 0, dl_tbf->imsi());
 		dl_tbf->m_wait_confirm = 1;
@@ -713,11 +711,7 @@ void gprs_rlcmac_pdch::rcv_control_ack(Packet_Control_Acknowledgement_t *packet,
 		return;
 	}
 	tbf->update_tlli(tlli);
-
-	if (tbf->new_tbf())
-		tbf->new_tbf()->update_ms(tlli, GPRS_RLCMAC_UL_TBF);
-	else
-		tbf->update_ms(tlli, GPRS_RLCMAC_UL_TBF);
+	tbf->update_ms(tlli, GPRS_RLCMAC_UL_TBF);
 
 	LOGP(DRLCMAC, LOGL_DEBUG, "RX: [PCU <- BTS] %s Packet Control Ack\n", tbf_name(tbf));
 	tbf->poll_state = GPRS_RLCMAC_POLL_NONE;
@@ -742,7 +736,7 @@ void gprs_rlcmac_pdch::rcv_control_ack(Packet_Control_Acknowledgement_t *packet,
 		tbf->n3105 = 0;
 		tbf->dl_ass_state = GPRS_RLCMAC_DL_ASS_NONE;
 
-		new_tbf = tbf->new_tbf();
+		new_tbf = tbf->ms() ? tbf->ms()->dl_tbf() : NULL;
 		if (!new_tbf) {
 			LOGP(DRLCMAC, LOGL_ERROR, "Got ACK, but DL "
 				"TBF is gone TLLI=0x%08x\n", tlli);
@@ -770,7 +764,7 @@ void gprs_rlcmac_pdch::rcv_control_ack(Packet_Control_Acknowledgement_t *packet,
 		tbf->n3105 = 0;
 		tbf->ul_ass_state = GPRS_RLCMAC_UL_ASS_NONE;
 
-		new_tbf = tbf->new_tbf();
+		new_tbf = tbf->ms() ? tbf->ms()->ul_tbf() : NULL;
 		if (!new_tbf) {
 			LOGP(DRLCMAC, LOGL_ERROR, "Got ACK, but UL "
 				"TBF is gone TLLI=0x%08x\n", tlli);
@@ -837,7 +831,11 @@ void gprs_rlcmac_pdch::rcv_control_dl_ack_nack(Packet_Downlink_Ack_Nack_t *ack_n
 	if (ack_nack->Exist_Channel_Request_Description) {
 		LOGP(DRLCMAC, LOGL_DEBUG, "MS requests UL TBF in ack "
 			"message, so we provide one:\n");
-		tbf->set_new_tbf(tbf_alloc_ul(bts_data(), tbf->trx->trx_no, tbf->ms_class, tbf->tlli(), tbf->ta, tbf));
+
+		/* This call will register the new TBF with the MS on success */
+		tbf_alloc_ul(bts_data(), tbf->trx->trx_no, tbf->ms_class,
+			tbf->tlli(), tbf->ta, tbf);
+
 		/* schedule uplink assignment */
 		tbf->ul_ass_state = GPRS_RLCMAC_UL_ASS_SEND_ASS;
 	}
@@ -908,7 +906,6 @@ void gprs_rlcmac_pdch::rcv_resource_request(Packet_Resource_Request_t *request,
 		if (!ul_tbf)
 			return;
 
-		ul_tbf->set_new_tbf(ul_tbf);
 		/* set control ts to current MS's TS, until assignment complete */
 		LOGP(DRLCMAC, LOGL_DEBUG, "Change control TS to %d until assinment is complete.\n", ts_no);
 		ul_tbf->control_ts = ts_no;