tipc: clean up definitions and usage of link flags

The status flag LINK_STOPPED is not needed any more, since the
mechanism for delayed deletion of links has been removed.
Likewise, LINK_STARTED and LINK_START_EVT are unnecessary,
because we can just as well start the link timer directly from
inside tipc_link_create().

We eliminate these flags in this commit.

Instead of the above flags, we now introduce three new link modes,
TIPC_LINK_OPEN, TIPC_LINK_BLOCKED and TIPC_LINK_TUNNEL. The values
indicate whether, and in the case of TIPC_LINK_TUNNEL, which, messages
the link is allowed to receive in this state. TIPC_LINK_BLOCKED also
blocks timer-driven protocol messages to be sent out, and any change
to the link FSM. Since the modes are mutually exclusive, we convert
them to state values, and rename the 'flags' field in struct tipc_link
to 'exec_mode'.

Finally, we move the #defines for link FSM states and events from link.h
into enums inside the file link.c, which is the real usage scope of
these definitions.

Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 58 insertions, 40 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
index c052437a7cfa..35a2da688db1 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -79,19 +79,49 @@ static const struct nla_policy tipc_nl_prop_policy[TIPC_NLA_PROP_MAX + 1] = {
 /*
  * Out-of-range value for link session numbers
  */
-#define INVALID_SESSION 0x10000
+#define WILDCARD_SESSION 0x10000
 
-/*
- * Link state events:
+/* State value stored in 'failover_pkts'
  */
-#define  STARTING_EVT    856384768	/* link processing trigger */
-#define  TRAFFIC_MSG_EVT 560815u	/* rx'd ??? */
-#define  SILENCE_EVT     560817u	/* timer dicovered silence from peer */
+#define FIRST_FAILOVER 0xffffu
 
-/*
- * State value stored in 'failover_pkts'
+/* Link FSM states and events:
  */
-#define FIRST_FAILOVER 0xffffu
+enum {
+	WORKING_WORKING,
+	WORKING_UNKNOWN,
+	RESET_RESET,
+	RESET_UNKNOWN
+};
+
+enum {
+	PEER_RESET_EVT    = RESET_MSG,
+	ACTIVATE_EVT      = ACTIVATE_MSG,
+	TRAFFIC_EVT,      /* Any other valid msg from peer */
+	SILENCE_EVT       /* Peer was silent during last timer interval*/
+};
+
+/* Link FSM state checking routines
+ */
+static int link_working_working(struct tipc_link *l)
+{
+	return l->state == WORKING_WORKING;
+}
+
+static int link_working_unknown(struct tipc_link *l)
+{
+	return l->state == WORKING_UNKNOWN;
+}
+
+static int link_reset_unknown(struct tipc_link *l)
+{
+	return l->state == RESET_UNKNOWN;
+}
+
+static int link_reset_reset(struct tipc_link *l)
+{
+	return l->state == RESET_RESET;
+}
 
 static void link_handle_out_of_seq_msg(struct tipc_link *link,
 				       struct sk_buff *skb);
@@ -268,7 +298,7 @@ struct tipc_link *tipc_link_create(struct tipc_node *n_ptr,
 		/* note: peer i/f name is updated by reset/activate message */
 	memcpy(&l_ptr->media_addr, media_addr, sizeof(*media_addr));
 	l_ptr->owner = n_ptr;
-	l_ptr->peer_session = INVALID_SESSION;
+	l_ptr->peer_session = WILDCARD_SESSION;
 	l_ptr->bearer_id = b_ptr->identity;
 	link_set_supervision_props(l_ptr, b_ptr->tolerance);
 	l_ptr->state = RESET_UNKNOWN;
@@ -297,8 +327,7 @@ struct tipc_link *tipc_link_create(struct tipc_node *n_ptr,
 	link_reset_statistics(l_ptr);
 	tipc_node_attach_link(n_ptr, l_ptr);
 	setup_timer(&l_ptr->timer, link_timeout, (unsigned long)l_ptr);
-	link_state_event(l_ptr, STARTING_EVT);
-
+	link_set_timer(l_ptr, l_ptr->keepalive_intv);
 	return l_ptr;
 }
 
@@ -311,7 +340,6 @@ void tipc_link_delete(struct tipc_link *l)
 	tipc_link_reset(l);
 	if (del_timer(&l->timer))
 		tipc_link_put(l);
-	l->flags |= LINK_STOPPED;
 	/* Delete link now, or when timer is finished: */
 	tipc_link_reset_fragments(l);
 	tipc_node_detach_link(l->owner, l);
@@ -438,7 +466,7 @@ void tipc_link_reset(struct tipc_link *l_ptr)
 	msg_set_session(l_ptr->pmsg, ((msg_session(l_ptr->pmsg) + 1) & 0xffff));
 
 	/* Link is down, accept any session */
-	l_ptr->peer_session = INVALID_SESSION;
+	l_ptr->peer_session = WILDCARD_SESSION;
 
 	/* Prepare for renewed mtu size negotiation */
 	l_ptr->mtu = l_ptr->advertised_mtu;
@@ -452,7 +480,7 @@ void tipc_link_reset(struct tipc_link *l_ptr)
 	tipc_bearer_remove_dest(owner->net, l_ptr->bearer_id, l_ptr->addr);
 
 	if (was_active_link && tipc_node_is_up(l_ptr->owner) && (pl != l_ptr)) {
-		l_ptr->flags |= LINK_FAILINGOVER;
+		l_ptr->exec_mode = TIPC_LINK_BLOCKED;
 		l_ptr->failover_checkpt = l_ptr->rcv_nxt;
 		pl->failover_pkts = FIRST_FAILOVER;
 		pl->failover_checkpt = l_ptr->rcv_nxt;
@@ -496,21 +524,14 @@ static void link_activate(struct tipc_link *link)
 static void link_state_event(struct tipc_link *l_ptr, unsigned int event)
 {
 	struct tipc_link *other;
-	unsigned long timer_intv = l_ptr->keepalive_intv;
-
-	if (l_ptr->flags & LINK_STOPPED)
-		return;
-
-	if (!(l_ptr->flags & LINK_STARTED) && (event != STARTING_EVT))
-		return;		/* Not yet. */
 
-	if (l_ptr->flags & LINK_FAILINGOVER)
+	if (l_ptr->exec_mode == TIPC_LINK_BLOCKED)
 		return;
 
 	switch (l_ptr->state) {
 	case WORKING_WORKING:
 		switch (event) {
-		case TRAFFIC_MSG_EVT:
+		case TRAFFIC_EVT:
 		case ACTIVATE_MSG:
 			l_ptr->silent_intv_cnt = 0;
 			break;
@@ -538,7 +559,7 @@ static void link_state_event(struct tipc_link *l_ptr, unsigned int event)
 		break;
 	case WORKING_UNKNOWN:
 		switch (event) {
-		case TRAFFIC_MSG_EVT:
+		case TRAFFIC_EVT:
 		case ACTIVATE_MSG:
 			l_ptr->state = WORKING_WORKING;
 			l_ptr->silent_intv_cnt = 0;
@@ -576,7 +597,7 @@ static void link_state_event(struct tipc_link *l_ptr, unsigned int event)
 		break;
 	case RESET_UNKNOWN:
 		switch (event) {
-		case TRAFFIC_MSG_EVT:
+		case TRAFFIC_EVT:
 			break;
 		case ACTIVATE_MSG:
 			other = node_active_link(l_ptr->owner, 0);
@@ -593,10 +614,6 @@ static void link_state_event(struct tipc_link *l_ptr, unsigned int event)
 			tipc_link_proto_xmit(l_ptr, ACTIVATE_MSG,
 					     1, 0, 0, 0);
 			break;
-		case STARTING_EVT:
-			l_ptr->flags |= LINK_STARTED;
-			link_set_timer(l_ptr, timer_intv);
-			break;
 		case SILENCE_EVT:
 			tipc_link_proto_xmit(l_ptr, RESET_MSG, 0, 0, 0, 0);
 			break;
@@ -606,7 +623,7 @@ static void link_state_event(struct tipc_link *l_ptr, unsigned int event)
 		break;
 	case RESET_RESET:
 		switch (event) {
-		case TRAFFIC_MSG_EVT:
+		case TRAFFIC_EVT:
 		case ACTIVATE_MSG:
 			other = node_active_link(l_ptr->owner, 0);
 			if (other && link_working_unknown(other))
@@ -975,7 +992,7 @@ static bool link_synch(struct tipc_link *l)
 	if (skb_queue_len(pl->inputq) > post_synch)
 		return false;
 synched:
-	l->flags &= ~LINK_SYNCHING;
+	l->exec_mode = TIPC_LINK_OPEN;
 	return true;
 }
 
@@ -1091,7 +1108,7 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
 			}
 
 			/* Traffic message. Conditionally activate link */
-			link_state_event(l_ptr, TRAFFIC_MSG_EVT);
+			link_state_event(l_ptr, TRAFFIC_EVT);
 
 			if (link_working_working(l_ptr)) {
 				/* Re-insert buffer in front of queue */
@@ -1112,7 +1129,8 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
 		l_ptr->silent_intv_cnt = 0;
 
 		/* Synchronize with parallel link if applicable */
-		if (unlikely((l_ptr->flags & LINK_SYNCHING) && !msg_dup(msg))) {
+		if (unlikely((l_ptr->exec_mode == TIPC_LINK_TUNNEL) &&
+			     !msg_dup(msg))) {
 			if (!link_synch(l_ptr))
 				goto unlock;
 		}
@@ -1193,7 +1211,7 @@ static void tipc_link_input(struct tipc_link *link, struct sk_buff *skb)
 	switch (msg_user(msg)) {
 	case TUNNEL_PROTOCOL:
 		if (msg_dup(msg)) {
-			link->flags |= LINK_SYNCHING;
+			link->exec_mode = TIPC_LINK_TUNNEL;
 			link->synch_point = msg_seqno(msg_get_wrapped(msg));
 			kfree_skb(skb);
 			break;
@@ -1315,7 +1333,7 @@ void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int probe_msg,
 	u16 last_rcv;
 
 	/* Don't send protocol message during link failover */
-	if (l_ptr->flags & LINK_FAILINGOVER)
+	if (l_ptr->exec_mode == TIPC_LINK_BLOCKED)
 		return;
 
 	/* Abort non-RESET send if communication with node is prohibited */
@@ -1390,7 +1408,7 @@ static void tipc_link_proto_rcv(struct tipc_link *l_ptr,
 	u32 msg_tol;
 	struct tipc_msg *msg = buf_msg(buf);
 
-	if (l_ptr->flags & LINK_FAILINGOVER)
+	if (l_ptr->exec_mode == TIPC_LINK_BLOCKED)
 		goto exit;
 
 	if (l_ptr->net_plane != msg_net_plane(msg))
@@ -1401,7 +1419,7 @@ static void tipc_link_proto_rcv(struct tipc_link *l_ptr,
 
 	case RESET_MSG:
 		if (!link_working_unknown(l_ptr) &&
-		    (l_ptr->peer_session != INVALID_SESSION)) {
+		    (l_ptr->peer_session != WILDCARD_SESSION)) {
 			if (less_eq(msg_session(msg), l_ptr->peer_session))
 				break; /* duplicate or old reset: ignore */
 		}
@@ -1465,7 +1483,7 @@ static void tipc_link_proto_rcv(struct tipc_link *l_ptr,
 		/* Record reception; force mismatch at next timeout: */
 		l_ptr->silent_intv_cnt = 0;
 
-		link_state_event(l_ptr, TRAFFIC_MSG_EVT);
+		link_state_event(l_ptr, TRAFFIC_EVT);
 		l_ptr->stats.recv_states++;
 		if (link_reset_unknown(l_ptr))
 			break;
@@ -1704,7 +1722,7 @@ static bool tipc_link_failover_rcv(struct tipc_link *link,
 	}
 exit:
 	if (!link->failover_pkts && pl)
-		pl->flags &= ~LINK_FAILINGOVER;
+		pl->exec_mode = TIPC_LINK_OPEN;
 	kfree_skb(*skb);
 	*skb = iskb;
 	return *skb;