Move WAIT_RELEASE tbf_state transition to tbf_fsm

While at it, method maybe_start_new_window is renamed to
rcvd_dl_final_ack to make more sense out of the code.

Related: OS#2709
Change-Id: Iebd650c1036ef2d5132789778be7117ce3391c01

4 files changed, 32 insertions, 8 deletions

diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index ed5003c9..6614366b 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -1219,8 +1219,9 @@ int gprs_rlcmac_dl_tbf::update_window(const uint8_t ssn, const uint8_t *rbb)
 }
 
 
-int gprs_rlcmac_dl_tbf::maybe_start_new_window()
+int gprs_rlcmac_dl_tbf::rcvd_dl_final_ack()
 {
+	osmo_fsm_inst_dispatch(this->state_fsm.fi, TBF_EV_FINAL_ACK_RECVD, NULL);
 	release();
 
 	/* check for LLC PDU in the LLC Queue */
@@ -1241,8 +1242,6 @@ int gprs_rlcmac_dl_tbf::release()
 	/* report all outstanding packets as received */
 	gprs_rlcmac_received_lost(this, received, 0);
 
-	TBF_SET_STATE(this, TBF_ST_WAIT_RELEASE);
-
 	/* start T3193 */
 	T_START(this, T3193, 3193, "release (DL-TBF)", true);
 
@@ -1292,7 +1291,7 @@ int gprs_rlcmac_dl_tbf::rcvd_dl_ack(bool final_ack, unsigned first_bsn,
 
 	if (final_ack) {
 		LOGPTBFDL(this, LOGL_DEBUG, "Final ACK received.\n");
-		rc = maybe_start_new_window();
+		rc = rcvd_dl_final_ack();
 	} else if (state_is(TBF_ST_FINISHED) && m_window.window_empty()) {
 		LOGPTBFDL(this, LOGL_NOTICE,
 			  "Received acknowledge of all blocks, but without final ack indication (don't worry)\n");
@@ -1309,7 +1308,7 @@ int gprs_rlcmac_dl_tbf::rcvd_dl_ack(bool final_ack, uint8_t ssn, uint8_t *rbb)
 		return update_window(ssn, rbb);
 
 	LOGPTBFDL(this, LOGL_DEBUG, "Final ACK received.\n");
-	return maybe_start_new_window();
+	return rcvd_dl_final_ack();
 }
 
 bool gprs_rlcmac_dl_tbf::dl_window_stalled() const
diff --git a/src/tbf_dl.h b/src/tbf_dl.h
index 58d863b3..af82a0cf 100644
--- a/src/tbf_dl.h
+++ b/src/tbf_dl.h
@@ -110,7 +110,7 @@ protected:
 					int index, int index2 = -1);
 	int update_window(const uint8_t ssn, const uint8_t *rbb);
 	int update_window(unsigned first_bsn, const struct bitvec *rbb);
-	int maybe_start_new_window();
+	int rcvd_dl_final_ack();
 	bool dl_window_stalled() const;
 	void reuse_tbf();
 	void start_llc_timer();
diff --git a/src/tbf_fsm.c b/src/tbf_fsm.c
index 8e0649da..d1b48d56 100644
--- a/src/tbf_fsm.c
+++ b/src/tbf_fsm.c
@@ -48,6 +48,7 @@ const struct value_string tbf_fsm_event_names[] = {
 	{ TBF_EV_ASSIGN_READY_CCCH, "ASSIGN_READY_CCCH" },
 	{ TBF_EV_LAST_DL_DATA_SENT, "LAST_DL_DATA_SENT" },
 	{ TBF_EV_LAST_UL_DATA_RECVD, "LAST_UL_DATA_RECVD" },
+	{ TBF_EV_FINAL_ACK_RECVD, "FINAL_ACK_RECVD" },
 	{ 0, NULL }
 };
 
@@ -147,6 +148,27 @@ static void st_flow(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 		/* All data has been sent or received, change state to FINISHED */
 		tbf_fsm_state_chg(fi, TBF_ST_FINISHED);
 		break;
+	case TBF_EV_FINAL_ACK_RECVD:
+		/* We received Final Ack (DL ACK/NACK) from MS. move to
+		   WAIT_RELEASE, we wait there for release or re-use the TBF in
+		   case we receive more DL data to tx */
+		tbf_fsm_state_chg(fi, TBF_ST_WAIT_RELEASE);
+		break;
+	default:
+		OSMO_ASSERT(0);
+	}
+}
+
+static void st_finished(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	//struct tbf_fsm_ctx *ctx = (struct tbf_fsm_ctx *)fi->priv;
+	switch (event) {
+	case TBF_EV_FINAL_ACK_RECVD:
+		/* We received Final Ack (DL ACK/NACK) from MS. move to
+		   WAIT_RELEASE, we wait there for release or re-use the TBF in
+		   case we receive more DL data to tx */
+		tbf_fsm_state_chg(fi, TBF_ST_WAIT_RELEASE);
+		break;
 	default:
 		OSMO_ASSERT(0);
 	}
@@ -196,7 +218,8 @@ static struct osmo_fsm_state tbf_fsm_states[] = {
 	[TBF_ST_FLOW] = {
 		.in_event_mask =
 			X(TBF_EV_LAST_DL_DATA_SENT) |
-			X(TBF_EV_LAST_UL_DATA_RECVD),
+			X(TBF_EV_LAST_UL_DATA_RECVD) |
+			X(TBF_EV_FINAL_ACK_RECVD),
 		.out_state_mask =
 			X(TBF_ST_FINISHED) |
 			X(TBF_ST_WAIT_RELEASE) |
@@ -206,10 +229,11 @@ static struct osmo_fsm_state tbf_fsm_states[] = {
 	},
 	[TBF_ST_FINISHED] = {
 		.in_event_mask =
-			0,
+			X(TBF_EV_FINAL_ACK_RECVD),
 		.out_state_mask =
 			X(TBF_ST_WAIT_RELEASE),
 		.name = "FINISHED",
+		.action = st_finished,
 	},
 	[TBF_ST_WAIT_RELEASE] = {
 		.in_event_mask =
diff --git a/src/tbf_fsm.h b/src/tbf_fsm.h
index ea0f58d1..1dba80ff 100644
--- a/src/tbf_fsm.h
+++ b/src/tbf_fsm.h
@@ -34,6 +34,7 @@ enum tbf_fsm_event {
 	TBF_EV_ASSIGN_READY_CCCH, /* TBF Start Time timer triggered */
 	TBF_EV_LAST_DL_DATA_SENT, /* DL TBF sends RLCMAC block containing last DL avilable data buffered */
 	TBF_EV_LAST_UL_DATA_RECVD, /* UL TBF sends RLCMAC block containing last UL data (cv=0) */
+	TBF_EV_FINAL_ACK_RECVD, /* DL ACK/NACK with FINAL_ACK=1 received from MS */
 };
 
 enum tbf_fsm_states {