pespin has uploaded this change for review.

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xua_default_lm_fsm: Avoid accessing asp after restart

Avoid restarting the ASP upon LM_E_SCTP_DISC_IND:
* The SCTP event may actually come from an existing call to
  osmo_ss7_asp_restart() which has called.
* For SCTP server asps, there's no need to actually restart the ASP,
  since we have to wait for client to connect to us again.
* For SCTP client asps, the lower layers are already triggering
  reconnect, no need to do anything other than waiting for SCTP_EST_IND.
* ASP may be no longer accessible after dropping conn if it was a dynamic
  SCTP-server one. Hence, better keep the call setting up the FSM in
the ASP in osmo_ss7_asp_restart(), where we know if asp is still alive.

Change-Id: I009a34d098abd61fa3c014787d52c09491fcab76
---
M src/osmo_ss7_asp.c
M src/xua_default_lm_fsm.c
2 files changed, 26 insertions(+), 28 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/libosmo-sigtran refs/changes/17/40217/1

diff --git a/src/osmo_ss7_asp.c b/src/osmo_ss7_asp.c
index 1c303b6..735c5fd 100644
--- a/src/osmo_ss7_asp.c
+++ b/src/osmo_ss7_asp.c
@@ -756,6 +756,16 @@
 		osmo_fsm_inst_term(asp->fi, OSMO_FSM_TERM_REQUEST, NULL);
 		OSMO_ASSERT(!asp->fi);
 	}
+
+	/* Apply default LM FSM for client ASP */
+	if (asp->cfg.proto != OSMO_SS7_ASP_PROT_IPA &&
+	    asp->cfg.role == OSMO_SS7_ASP_ROLE_ASP &&
+	    !asp->cfg.is_server) {
+		osmo_ss7_asp_use_default_lm(asp, LOGL_DEBUG);
+	} else {
+		osmo_ss7_asp_remove_default_lm(asp);
+	}
+
 	if ((rc = xua_asp_fsm_start(asp, asp->cfg.role, LOGL_DEBUG)) < 0)
 		return rc;
 	OSMO_ASSERT(asp->fi);
@@ -1323,15 +1333,6 @@
 	* specific default values */
 	ss7_asp_set_default_peer_hosts(asp);
 
-	/* Apply default LM FSM for client ASP */
-	if (asp->cfg.proto != OSMO_SS7_ASP_PROT_IPA &&
-	    asp->cfg.role == OSMO_SS7_ASP_ROLE_ASP &&
-	    !asp->cfg.is_server) {
-		osmo_ss7_asp_use_default_lm(asp, LOGL_DEBUG);
-	} else {
-		osmo_ss7_asp_remove_default_lm(asp);
-	}
-
 	osmo_ss7_asp_restart(asp);
 }
 
diff --git a/src/xua_default_lm_fsm.c b/src/xua_default_lm_fsm.c
index 0952c9e..3aceb26 100644
--- a/src/xua_default_lm_fsm.c
+++ b/src/xua_default_lm_fsm.c
@@ -160,17 +160,6 @@
 	return 0;
 }
 
-static void restart_asp(struct osmo_fsm_inst *fi)
-{
-	struct lm_fsm_priv *lmp = fi->priv;
-	struct osmo_ss7_asp *asp = lmp->asp;
-	int log_level = fi->log_level;
-
-	osmo_ss7_asp_restart(asp);
-	osmo_ss7_asp_use_default_lm(asp, log_level);
-}
-
-
 static void lm_idle(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	struct lm_fsm_priv *lmp = fi->priv;
@@ -317,7 +306,7 @@
 		OSMO_ASSERT(oxp->oph.operation == PRIM_OP_INDICATION);
 		if (oxp->u.notify.status_type == M3UA_NOTIFY_T_STATCHG &&
 		    oxp->u.notify.status_info != M3UA_NOTIFY_I_AS_ACT)
-			restart_asp(fi);
+			lm_fsm_state_chg(fi, S_IDLE);
 		break;
 	}
 }
@@ -326,7 +315,7 @@
 {
 	switch (event) {
 	case LM_E_SCTP_DISC_IND:
-		restart_asp(fi);
+		lm_fsm_state_chg(fi, S_IDLE);
 		break;
 	}
 }
@@ -334,30 +323,38 @@
 static const struct osmo_fsm_state lm_states[] = {
 	[S_IDLE] = {
 		.in_event_mask = S(LM_E_SCTP_EST_IND),
-		.out_state_mask = S(S_WAIT_ASP_UP),
+		.out_state_mask = S(S_IDLE) |
+				  S(S_WAIT_ASP_UP),
 		.name = "IDLE",
 		.action = lm_idle,
 	},
 	[S_WAIT_ASP_UP] = {
 		.in_event_mask = S(LM_E_ASP_UP_CONF),
-		.out_state_mask = S(S_WAIT_NOTIFY),
+		.out_state_mask = S(S_IDLE) |
+				  S(S_WAIT_NOTIFY),
 		.name = "WAIT_ASP_UP",
 		.action = lm_wait_asp_up,
 	},
 	[S_WAIT_NOTIFY] = {
-		.in_event_mask = S(LM_E_AS_INACTIVE_IND) | S(LM_E_NOTIFY_IND),
-		.out_state_mask = S(S_RKM_REG) | S(S_ACTIVE),
+		.in_event_mask = S(LM_E_AS_INACTIVE_IND) |
+				 S(LM_E_NOTIFY_IND),
+		.out_state_mask = S(S_IDLE) |
+				  S(S_RKM_REG) |
+				  S(S_ACTIVE),
 		.name = "WAIT_NOTIFY",
 		.action = lm_wait_notify,
 	},
 	[S_RKM_REG] = {
 		.in_event_mask = S(LM_E_RKM_REG_CONF),
-		.out_state_mask = S(S_WAIT_NOTIFY),
+		.out_state_mask = S(S_IDLE) |
+				  S(S_WAIT_NOTIFY),
 		.name = "RKM_REG",
 		.action = lm_rkm_reg,
 	},
 	[S_ACTIVE] = {
-		.in_event_mask = S(LM_E_AS_INACTIVE_IND) | S(LM_E_NOTIFY_IND),
+		.in_event_mask = S(LM_E_AS_INACTIVE_IND) |
+				 S(LM_E_NOTIFY_IND),
+		.out_state_mask = S(S_IDLE),
 		.name = "ACTIVE",
 		.action = lm_active,
 	},

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