tbf_dl_fsm: Ignore DL_ACKNACK_MISS events in WAIT_{RELEASE,REUSE_TFI} states

If in those states, we already left the FINISHED step which means we
already received a FinalACk previously, hence it means we are missing
requested retransmissions of the last DL ACK/NACK due to fn-advance
(several DL blocks in transit before receiving UL response).

Change-Id: Ib0f23a9cc3c614fe428b682e01502930cd2e478f
---
M src/tbf_dl_fsm.c
1 file changed, 26 insertions(+), 0 deletions(-)

diff --git a/src/tbf_dl_fsm.c b/src/tbf_dl_fsm.c
index 557fb7a..d604f6f 100644
--- a/src/tbf_dl_fsm.c
+++ b/src/tbf_dl_fsm.c
@@ -286,6 +286,11 @@
 	case TBF_EV_FINAL_ACK_RECVD:
 		/* ignore, duplicate ACK, we already know about since we left ST_FINISHED */
 		break;
+	case TBF_EV_DL_ACKNACK_MISS:
+		/* ignore, miss for retransmitted ACK, but a previous one was
+		 * already ACKED since we left ST_FINISHED. This happens due to
+		 * fn-advance scheduling several DL blocks in advance. */
+		break;
 	default:
 		OSMO_ASSERT(0);
 	}
@@ -320,6 +325,11 @@
 	case TBF_EV_FINAL_ACK_RECVD:
 		/* ignore, duplicate ACK, we already know about since we left ST_FINISHED */
 		break;
+	case TBF_EV_DL_ACKNACK_MISS:
+		/* ignore, miss for retransmitted ACK, but a previous one was
+		 * already ACKED since we left ST_FINISHED. This happens due to
+		 * fn-advance scheduling several DL blocks in advance. */
+		break;
 	default:
 		OSMO_ASSERT(0);
 	}
@@ -450,6 +460,7 @@
 	},
 	[TBF_ST_WAIT_RELEASE] = {
 		.in_event_mask =
+			X(TBF_EV_DL_ACKNACK_MISS) |
 			X(TBF_EV_FINAL_ACK_RECVD) |
 			X(TBF_EV_MAX_N3105),
 		.out_state_mask =
@@ -461,6 +472,7 @@
 	},
 	[TBF_ST_WAIT_REUSE_TFI] = {
 		.in_event_mask =
+			X(TBF_EV_DL_ACKNACK_MISS) |
 			X(TBF_EV_FINAL_ACK_RECVD),
 		.out_state_mask =
 			X(TBF_ST_RELEASING),

