nacc_fsm: nacc_fsm: Support receiving Pkt Cell Change Notify in state WAIT_REQUEST_SI

Similar to what's done in the previous commit, but this time when we are
further forward in the resolution process.
This can be triggered for instance because we are taking too much time
to resolve and MS has timer to retransmit the Pkt cell Change Notify in
case no response was received in time.

This commit fixes osmo-pcu exiting due to ASSERT(0) since the event was
already accepted but not being handled in the state function.

Related: SYS#4909
Change-Id: I0c29e5979fec6eebe9dfb151907a4cd2f5e4a737

1 files changed, 32 insertions, 16 deletions

diff --git a/src/nacc_fsm.c b/src/nacc_fsm.c
index 8d5f23d2..5bc9c128 100644
--- a/src/nacc_fsm.c
+++ b/src/nacc_fsm.c
@@ -309,6 +309,29 @@ static void bts_fill_si_cache_value(const struct gprs_rlcmac_bts *bts, struct si
 	}
 }
 
+/* Called on event NACC_EV_RX_CELL_CHG_NOTIFICATION on states after
+ * WAIT_RESOLVE_RAC_CI. Ignore duplicate messages, transition back if target
+ * cell changed.
+ */
+static void handle_retrans_pkt_cell_chg_notif(struct nacc_fsm_ctx *ctx, const Packet_Cell_Change_Notification_t *notif)
+{
+	struct gprs_rlcmac_bts *bts = ctx->ms->bts;
+	struct neigh_cache_entry_key neigh_key;
+
+	if (fill_neigh_key_from_bts_pkt_cell_chg_not(&neigh_key, bts, notif) < 0) {
+		LOGPFSML(ctx->fi, LOGL_NOTICE, "TargetCell type=0x%x not supported\n",
+			 notif->Target_Cell.UnionType);
+		nacc_fsm_state_chg(ctx->fi, NACC_ST_TX_CELL_CHG_CONTINUE);
+		return;
+	}
+	/* If tgt cell changed, restart resolving it */
+	if (!neigh_cache_entry_key_eq(&ctx->neigh_key, &neigh_key)) {
+		ctx->neigh_key = neigh_key;
+		nacc_fsm_state_chg(ctx->fi, NACC_ST_WAIT_RESOLVE_RAC_CI);
+	}
+	/* else: ignore it, it's a dup, carry on what we were doing */
+}
+
 ////////////////
 // FSM states //
 ////////////////
@@ -398,28 +421,15 @@ err_term:
 	nacc_fsm_state_chg(fi, NACC_ST_TX_CELL_CHG_CONTINUE);
 }
 
-
 static void st_wait_resolve_rac_ci(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	struct nacc_fsm_ctx *ctx = (struct nacc_fsm_ctx *)fi->priv;
-	struct gprs_rlcmac_bts *bts = ctx->ms->bts;
-	Packet_Cell_Change_Notification_t *notif;
-	struct neigh_cache_entry_key neigh_key;
+	const Packet_Cell_Change_Notification_t *notif;
 
 	switch (event) {
 	case NACC_EV_RX_CELL_CHG_NOTIFICATION:
-		notif = (Packet_Cell_Change_Notification_t *)data;
-		if (fill_neigh_key_from_bts_pkt_cell_chg_not(&neigh_key, bts, notif) < 0) {
-			LOGPFSML(fi, LOGL_NOTICE, "TargetCell type=0x%x not supported\n",
-				 notif->Target_Cell.UnionType);
-			nacc_fsm_state_chg(fi, NACC_ST_TX_CELL_CHG_CONTINUE);
-			return;
-		}
-		/* If tgt cell changed, restart resolving it */
-		if (!neigh_cache_entry_key_eq(&ctx->neigh_key, &neigh_key)) {
-			ctx->neigh_key = neigh_key;
-			nacc_fsm_state_chg(fi, NACC_ST_WAIT_RESOLVE_RAC_CI);
-		}
+		notif = (const Packet_Cell_Change_Notification_t *)data;
+		handle_retrans_pkt_cell_chg_notif(ctx, notif);
 		break;
 	case NACC_EV_RX_RAC_CI:
 		/* Assumption: ctx->cgi_ps has been filled by caller of the event */
@@ -489,9 +499,14 @@ static void st_wait_request_si_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_
 static void st_wait_request_si(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	struct nacc_fsm_ctx *ctx = (struct nacc_fsm_ctx *)fi->priv;
+	const Packet_Cell_Change_Notification_t *notif;
 	struct si_cache_entry *entry;
 
 	switch (event) {
+	case NACC_EV_RX_CELL_CHG_NOTIFICATION:
+		notif = (const Packet_Cell_Change_Notification_t *)data;
+		handle_retrans_pkt_cell_chg_notif(ctx, notif);
+		break;
 	case NACC_EV_RX_SI:
 		entry = (struct si_cache_entry *)data;
 		/* Copy info since cache can be deleted at any point */
@@ -629,6 +644,7 @@ static struct osmo_fsm_state nacc_fsm_states[] = {
 			X(NACC_EV_RX_CELL_CHG_NOTIFICATION) |
 			X(NACC_EV_RX_SI),
 		.out_state_mask =
+			X(NACC_ST_WAIT_RESOLVE_RAC_CI) |
 			X(NACC_ST_TX_NEIGHBOUR_DATA) |
 			X(NACC_ST_TX_CELL_CHG_CONTINUE),
 		.name = "WAIT_REQUEST_SI",