tipc: introduce link entry structure to struct tipc_node

struct 'tipc_node' currently contains two arrays for link attributes,
one for the link pointers, and one for the usable link MTUs.

We now group those into a new struct 'tipc_link_entry', and intoduce
one single array consisting of such enties. Apart from being a cosmetic
improvement, this is a starting point for the strict master-slave
relation between node and link that we will introduce in the following
commits.

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>

net/tipc/bcast.c

@@ -413,7 +413,7 @@ static void bclink_accept_pkt(struct tipc_node *node, u32 seqno)
 	 * all nodes in the cluster don't ACK at the same time
 	 */
 	if (((seqno - tn->own_addr) % TIPC_MIN_LINK_WIN) == 0) {
-		tipc_link_proto_xmit(node->active_links[node->addr & 1],
+		tipc_link_proto_xmit(node_active_link(node, node->addr),
 				     STATE_MSG, 0, 0, 0, 0);
 		tn->bcl->stats.sent_acks++;
 	}

net/tipc/discover.c

@@ -170,7 +170,7 @@ void tipc_disc_rcv(struct net *net, struct sk_buff *buf,
 		return;
 	tipc_node_lock(node);
 	node->capabilities = caps;
-	link = node->links[bearer->identity];
+	link = node->links[bearer->identity].link;
 
 	/* Prepare to validate requesting node's signature and media address */
 	sign_match = (signature == node->signature);

net/tipc/link.c

@@ -132,9 +132,11 @@ static void tipc_link_put(struct tipc_link *l_ptr)
 
 static struct tipc_link *tipc_parallel_link(struct tipc_link *l)
 {
-	if (l->owner->active_links[0] != l)
-		return l->owner->active_links[0];
-	return l->owner->active_links[1];
+	struct tipc_node *n = l->owner;
+
+	if (node_active_link(n, 0) != l)
+		return node_active_link(n, 0);
+	return node_active_link(n, 1);
 }
 
 /*
@@ -147,10 +149,11 @@ int tipc_link_is_up(struct tipc_link *l_ptr)
 	return link_working_working(l_ptr) || link_working_unknown(l_ptr);
 }
 
-int tipc_link_is_active(struct tipc_link *l_ptr)
+int tipc_link_is_active(struct tipc_link *l)
 {
-	return	(l_ptr->owner->active_links[0] == l_ptr) ||
-		(l_ptr->owner->active_links[1] == l_ptr);
+	struct tipc_node *n = l->owner;
+
+	return (node_active_link(n, 0) == l) || (node_active_link(n, 1) == l);
 }
 
 /**
@@ -240,7 +243,7 @@ struct tipc_link *tipc_link_create(struct tipc_node *n_ptr,
 		return NULL;
 	}
 
-	if (n_ptr->links[b_ptr->identity]) {
+	if (n_ptr->links[b_ptr->identity].link) {
 		tipc_addr_string_fill(addr_string, n_ptr->addr);
 		pr_err("Attempt to establish second link on <%s> to %s\n",
 		       b_ptr->name, addr_string);
@@ -321,7 +324,7 @@ void tipc_link_delete_list(struct net *net, unsigned int bearer_id)
 	rcu_read_lock();
 	list_for_each_entry_rcu(node, &tn->node_list, list) {
 		tipc_node_lock(node);
-		link = node->links[bearer_id];
+		link = node->links[bearer_id].link;
 		if (link)
 			tipc_link_delete(link);
 		tipc_node_unlock(node);
@@ -446,7 +449,7 @@ void tipc_link_reset(struct tipc_link *l_ptr)
 	if ((prev_state == RESET_UNKNOWN) || (prev_state == RESET_RESET))
 		return;
 
-	tipc_node_link_down(l_ptr->owner, l_ptr);
+	tipc_node_link_down(l_ptr->owner, l_ptr->bearer_id);
 	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)) {
@@ -482,7 +485,7 @@ static void link_activate(struct tipc_link *link)
 	link->rcv_nxt = 1;
 	link->stats.recv_info = 1;
 	link->silent_intv_cnt = 0;
-	tipc_node_link_up(node, link);
+	tipc_node_link_up(node, link->bearer_id);
 	tipc_bearer_add_dest(node->net, link->bearer_id, link->addr);
 }
 
@@ -577,7 +580,7 @@ static void link_state_event(struct tipc_link *l_ptr, unsigned int event)
 		case TRAFFIC_MSG_EVT:
 			break;
 		case ACTIVATE_MSG:
-			other = l_ptr->owner->active_links[0];
+			other = node_active_link(l_ptr->owner, 0);
 			if (other && link_working_unknown(other))
 				break;
 			l_ptr->state = WORKING_WORKING;
@@ -606,7 +609,7 @@ static void link_state_event(struct tipc_link *l_ptr, unsigned int event)
 		switch (event) {
 		case TRAFFIC_MSG_EVT:
 		case ACTIVATE_MSG:
-			other = l_ptr->owner->active_links[0];
+			other = node_active_link(l_ptr->owner, 0);
 			if (other && link_working_unknown(other))
 				break;
 			l_ptr->state = WORKING_WORKING;
@@ -755,7 +758,7 @@ int tipc_link_xmit(struct net *net, struct sk_buff_head *list, u32 dnode,
 	node = tipc_node_find(net, dnode);
 	if (node) {
 		tipc_node_lock(node);
-		link = node->active_links[selector & 1];
+		link = node_active_link(node, selector & 1);
 		if (link)
 			rc = __tipc_link_xmit(net, link, list);
 		tipc_node_unlock(node);
@@ -858,9 +861,9 @@ void tipc_link_reset_all(struct tipc_node *node)
 		tipc_addr_string_fill(addr_string, node->addr));
 
 	for (i = 0; i < MAX_BEARERS; i++) {
-		if (node->links[i]) {
-			link_print(node->links[i], "Resetting link\n");
-			tipc_link_reset(node->links[i]);
+		if (node->links[i].link) {
+			link_print(node->links[i].link, "Resetting link\n");
+			tipc_link_reset(node->links[i].link);
 		}
 	}
 
@@ -1029,7 +1032,7 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
 
 		tipc_node_lock(n_ptr);
 		/* Locate unicast link endpoint that should handle message */
-		l_ptr = n_ptr->links[b_ptr->identity];
+		l_ptr = n_ptr->links[b_ptr->identity].link;
 		if (unlikely(!l_ptr))
 			goto unlock;
 
@@ -1496,7 +1499,7 @@ static void tipc_link_tunnel_xmit(struct tipc_link *l_ptr,
 	struct sk_buff *skb;
 	u32 length = msg_size(msg);
 
-	tunnel = l_ptr->owner->active_links[selector & 1];
+	tunnel = node_active_link(l_ptr->owner, selector & 1);
 	if (!tipc_link_is_up(tunnel)) {
 		pr_warn("%stunnel link no longer available\n", link_co_err);
 		return;
@@ -1522,7 +1525,7 @@ static void tipc_link_tunnel_xmit(struct tipc_link *l_ptr,
 void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
 {
 	int msgcount;
-	struct tipc_link *tunnel = l_ptr->owner->active_links[0];
+	struct tipc_link *tunnel = node_active_link(l_ptr->owner, 0);
 	struct tipc_msg tunnel_hdr;
 	struct sk_buff *skb;
 	int split_bundles;
@@ -1556,8 +1559,8 @@ void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
 		return;
 	}
 
-	split_bundles = (l_ptr->owner->active_links[0] !=
-			 l_ptr->owner->active_links[1]);
+	split_bundles = (node_active_link(l_ptr->owner, 0) !=
+			 node_active_link(l_ptr->owner, 0));
 
 	skb_queue_walk(&l_ptr->transmq, skb) {
 		struct tipc_msg *msg = buf_msg(skb);
@@ -1660,7 +1663,7 @@ static bool tipc_link_failover_rcv(struct tipc_link *link,
 	if (bearer_id == link->bearer_id)
 		goto exit;
 
-	pl = link->owner->links[bearer_id];
+	pl = link->owner->links[bearer_id].link;
 	if (pl && tipc_link_is_up(pl))
 		tipc_link_reset(pl);
 
@@ -1743,7 +1746,7 @@ static struct tipc_node *tipc_link_find_owner(struct net *net,
 	list_for_each_entry_rcu(n_ptr, &tn->node_list, list) {
 		tipc_node_lock(n_ptr);
 		for (i = 0; i < MAX_BEARERS; i++) {
-			l_ptr = n_ptr->links[i];
+			l_ptr = n_ptr->links[i].link;
 			if (l_ptr && !strcmp(l_ptr->name, link_name)) {
 				*bearer_id = i;
 				found_node = n_ptr;
@@ -1865,7 +1868,7 @@ int tipc_nl_link_set(struct sk_buff *skb, struct genl_info *info)
 
 	tipc_node_lock(node);
 
-	link = node->links[bearer_id];
+	link = node->links[bearer_id].link;
 	if (!link) {
 		res = -EINVAL;
 		goto out;
@@ -2055,10 +2058,11 @@ static int __tipc_nl_add_node_links(struct net *net, struct tipc_nl_msg *msg,
 	for (i = *prev_link; i < MAX_BEARERS; i++) {
 		*prev_link = i;
 
-		if (!node->links[i])
+		if (!node->links[i].link)
 			continue;
 
-		err = __tipc_nl_add_link(net, msg, node->links[i], NLM_F_MULTI);
+		err = __tipc_nl_add_link(net, msg,
+					 node->links[i].link, NLM_F_MULTI);
 		if (err)
 			return err;
 	}
@@ -2172,7 +2176,7 @@ int tipc_nl_link_get(struct sk_buff *skb, struct genl_info *info)
 			return -EINVAL;
 
 		tipc_node_lock(node);
-		link = node->links[bearer_id];
+		link = node->links[bearer_id].link;
 		if (!link) {
 			tipc_node_unlock(node);
 			nlmsg_free(msg.skb);
@@ -2227,7 +2231,7 @@ int tipc_nl_link_reset_stats(struct sk_buff *skb, struct genl_info *info)
 
 	tipc_node_lock(node);
 
-	link = node->links[bearer_id];
+	link = node->links[bearer_id].link;
 	if (!link) {
 		tipc_node_unlock(node);
 		return -EINVAL;

net/tipc/name_distr.c

@@ -96,7 +96,7 @@ void named_cluster_distribute(struct net *net, struct sk_buff *skb)
 		dnode = node->addr;
 		if (in_own_node(net, dnode))
 			continue;
-		if (!tipc_node_active_links(node))
+		if (!tipc_node_is_up(node))
 			continue;
 		oskb = pskb_copy(skb, GFP_ATOMIC);
 		if (!oskb)

net/tipc/node.c

@@ -224,126 +224,119 @@ void tipc_node_remove_conn(struct net *net, u32 dnode, u32 port)
  *
  * Link becomes active (alone or shared) or standby, depending on its priority.
  */
-void tipc_node_link_up(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
+void tipc_node_link_up(struct tipc_node *n, int bearer_id)
 {
-	struct tipc_link **active = &n_ptr->active_links[0];
+	struct tipc_link_entry **actv = &n->active_links[0];
+	struct tipc_link_entry *le = &n->links[bearer_id];
+	struct tipc_link *l = le->link;
 
-	n_ptr->working_links++;
-	n_ptr->action_flags |= TIPC_NOTIFY_LINK_UP;
-	n_ptr->link_id = l_ptr->peer_bearer_id << 16 | l_ptr->bearer_id;
+	/* Leave room for tunnel header when returning 'mtu' to users: */
+	n->links[bearer_id].mtu = l->mtu - INT_H_SIZE;
+
+	n->working_links++;
+	n->action_flags |= TIPC_NOTIFY_LINK_UP;
+	n->link_id = l->peer_bearer_id << 16 | l->bearer_id;
 
 	pr_debug("Established link <%s> on network plane %c\n",
-		 l_ptr->name, l_ptr->net_plane);
+		 l->name, l->net_plane);
 
-	if (!active[0]) {
-		active[0] = active[1] = l_ptr;
-		node_established_contact(n_ptr);
-		goto exit;
+	/* No active links ? => take both active slots */
+	if (!actv[0]) {
+		actv[0] = le;
+		actv[1] = le;
+		node_established_contact(n);
+		return;
 	}
-	if (l_ptr->priority < active[0]->priority) {
-		pr_debug("New link <%s> becomes standby\n", l_ptr->name);
-		goto exit;
+	if (l->priority < actv[0]->link->priority) {
+		pr_debug("New link <%s> becomes standby\n", l->name);
+		return;
 	}
-	tipc_link_dup_queue_xmit(active[0], l_ptr);
-	if (l_ptr->priority == active[0]->priority) {
-		active[0] = l_ptr;
-		goto exit;
+	tipc_link_dup_queue_xmit(actv[0]->link, l);
+
+	/* Take one active slot if applicable */
+	if (l->priority == actv[0]->link->priority) {
+		actv[0] = le;
+		return;
 	}
-	pr_debug("Old link <%s> becomes standby\n", active[0]->name);
-	if (active[1] != active[0])
-		pr_debug("Old link <%s> becomes standby\n", active[1]->name);
-	active[0] = active[1] = l_ptr;
-exit:
-	/* Leave room for changeover header when returning 'mtu' to users: */
-	n_ptr->act_mtus[0] = active[0]->mtu - INT_H_SIZE;
-	n_ptr->act_mtus[1] = active[1]->mtu - INT_H_SIZE;
+	/* Higher prio than current active? => take both active slots */
+	pr_debug("Old l <%s> becomes standby\n", actv[0]->link->name);
+	if (actv[1] != actv[0])
+		pr_debug("Old link <%s> now standby\n", actv[1]->link->name);
+	actv[0] = le;
+	actv[1] = le;
 }
 
 /**
- * node_select_active_links - select active link
+ * node_select_active_links - select which working links should be active
  */
-static void node_select_active_links(struct tipc_node *n_ptr)
+static void node_select_active_links(struct tipc_node *n)
 {
-	struct tipc_link **active = &n_ptr->active_links[0];
-	u32 i;
-	u32 highest_prio = 0;
+	struct tipc_link_entry **actv = &n->active_links[0];
+	struct tipc_link *l;
+	u32 b, highest = 0;
 
-	active[0] = active[1] = NULL;
-
-	for (i = 0; i < MAX_BEARERS; i++) {
-		struct tipc_link *l_ptr = n_ptr->links[i];
+	actv[0] = NULL;
+	actv[1] = NULL;
 
-		if (!l_ptr || !tipc_link_is_up(l_ptr) ||
-		    (l_ptr->priority < highest_prio))
+	for (b = 0; b < MAX_BEARERS; b++) {
+		l = n->links[b].link;
+		if (!l || !tipc_link_is_up(l) || (l->priority < highest))
+			continue;
+		if (l->priority > highest) {
+			highest = l->priority;
+			actv[0] = &n->links[b];
+			actv[1] = &n->links[b];
 			continue;
-
-		if (l_ptr->priority > highest_prio) {
-			highest_prio = l_ptr->priority;
-			active[0] = active[1] = l_ptr;
-		} else {
-			active[1] = l_ptr;
 		}
+		actv[1] = &n->links[b];
 	}
 }
 
 /**
  * tipc_node_link_down - handle loss of link
  */
-void tipc_node_link_down(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
+void tipc_node_link_down(struct tipc_node *n, int bearer_id)
 {
-	struct tipc_net *tn = net_generic(n_ptr->net, tipc_net_id);
-	struct tipc_link **active;
+	struct tipc_link_entry **actv = &n->active_links[0];
+	struct tipc_link_entry *le = &n->links[bearer_id];
+	struct tipc_link *l = le->link;
 
-	n_ptr->working_links--;
-	n_ptr->action_flags |= TIPC_NOTIFY_LINK_DOWN;
-	n_ptr->link_id = l_ptr->peer_bearer_id << 16 | l_ptr->bearer_id;
+	n->working_links--;
+	n->action_flags |= TIPC_NOTIFY_LINK_DOWN;
+	n->link_id = l->peer_bearer_id << 16 | l->bearer_id;
 
-	if (!tipc_link_is_active(l_ptr)) {
+	if (!tipc_link_is_active(l)) {
 		pr_debug("Lost standby link <%s> on network plane %c\n",
-			 l_ptr->name, l_ptr->net_plane);
+			 l->name, l->net_plane);
 		return;
 	}
 	pr_debug("Lost link <%s> on network plane %c\n",
-		 l_ptr->name, l_ptr->net_plane);
-
-	active = &n_ptr->active_links[0];
-	if (active[0] == l_ptr)
-		active[0] = active[1];
-	if (active[1] == l_ptr)
-		active[1] = active[0];
-	if (active[0] == l_ptr)
-		node_select_active_links(n_ptr);
-	if (tipc_node_is_up(n_ptr))
-		tipc_link_failover_send_queue(l_ptr);
-	else
-		node_lost_contact(n_ptr);
+		 l->name, l->net_plane);
 
-	/* Leave room for changeover header when returning 'mtu' to users: */
-	if (active[0]) {
-		n_ptr->act_mtus[0] = active[0]->mtu - INT_H_SIZE;
-		n_ptr->act_mtus[1] = active[1]->mtu - INT_H_SIZE;
-		return;
-	}
-	/* Loopback link went down? No fragmentation needed from now on. */
-	if (n_ptr->addr == tn->own_addr) {
-		n_ptr->act_mtus[0] = MAX_MSG_SIZE;
-		n_ptr->act_mtus[1] = MAX_MSG_SIZE;
-	}
-}
+	/* Resdistribute active slots if applicable */
+	if (actv[0] == le)
+		actv[0] = actv[1];
+	if (actv[1] == le)
+		actv[1] = actv[0];
 
-int tipc_node_active_links(struct tipc_node *n_ptr)
-{
-	return n_ptr->active_links[0] != NULL;
+	/* Last link of this priority? => select other ones if available */
+	if (actv[0] == le)
+		node_select_active_links(n);
+
+	if (tipc_node_is_up(n))
+		tipc_link_failover_send_queue(l);
+	else
+		node_lost_contact(n);
 }
 
-int tipc_node_is_up(struct tipc_node *n_ptr)
+bool tipc_node_is_up(struct tipc_node *n)
 {
-	return tipc_node_active_links(n_ptr);
+	return n->active_links[0];
 }
 
 void tipc_node_attach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
 {
-	n_ptr->links[l_ptr->bearer_id] = l_ptr;
+	n_ptr->links[l_ptr->bearer_id].link = l_ptr;
 	n_ptr->link_cnt++;
 }
 
@@ -352,9 +345,9 @@ void tipc_node_detach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
 	int i;
 
 	for (i = 0; i < MAX_BEARERS; i++) {
-		if (l_ptr != n_ptr->links[i])
+		if (l_ptr != n_ptr->links[i].link)
 			continue;
-		n_ptr->links[i] = NULL;
+		n_ptr->links[i].link = NULL;
 		n_ptr->link_cnt--;
 	}
 }
@@ -396,7 +389,7 @@ static void node_lost_contact(struct tipc_node *n_ptr)
 
 	/* Abort any ongoing link failover */
 	for (i = 0; i < MAX_BEARERS; i++) {
-		struct tipc_link *l_ptr = n_ptr->links[i];
+		struct tipc_link *l_ptr = n_ptr->links[i].link;
 		if (!l_ptr)
 			continue;
 		l_ptr->flags &= ~LINK_FAILINGOVER;
@@ -453,7 +446,7 @@ int tipc_node_get_linkname(struct net *net, u32 bearer_id, u32 addr,
 		goto exit;
 
 	tipc_node_lock(node);
-	link = node->links[bearer_id];
+	link = node->links[bearer_id].link;
 	if (link) {
 		strncpy(linkname, link->name, len);
 		err = 0;

net/tipc/node.h

@@ -89,6 +89,11 @@ struct tipc_node_bclink {
 	bool recv_permitted;
 };
 
+struct tipc_link_entry {
+	struct tipc_link *link;
+	u32 mtu;
+};
+
 /**
  * struct tipc_node - TIPC node structure
  * @addr: network address of node
@@ -98,9 +103,8 @@ struct tipc_node_bclink {
  * @hash: links to adjacent nodes in unsorted hash chain
  * @inputq: pointer to input queue containing messages for msg event
  * @namedq: pointer to name table input queue with name table messages
- * @curr_link: the link holding the node lock, if any
- * @active_links: pointers to active links to node
- * @links: pointers to all links to node
+ * @active_links: pointer into links[] array, identifying which links are active
+ * @links: array containing references to all links to node
  * @action_flags: bit mask of different types of node actions
  * @bclink: broadcast-related info
  * @list: links to adjacent nodes in sorted list of cluster's nodes
@@ -120,9 +124,8 @@ struct tipc_node {
 	struct hlist_node hash;
 	struct sk_buff_head *inputq;
 	struct sk_buff_head *namedq;
-	struct tipc_link *active_links[2];
-	u32 act_mtus[2];
-	struct tipc_link *links[MAX_BEARERS];
+	struct tipc_link_entry *active_links[2];
+	struct tipc_link_entry links[MAX_BEARERS];
 	int action_flags;
 	struct tipc_node_bclink bclink;
 	struct list_head list;
@@ -142,10 +145,9 @@ struct tipc_node *tipc_node_create(struct net *net, u32 addr);
 void tipc_node_stop(struct net *net);
 void tipc_node_attach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
 void tipc_node_detach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
-void tipc_node_link_down(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
-void tipc_node_link_up(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
-int tipc_node_active_links(struct tipc_node *n_ptr);
-int tipc_node_is_up(struct tipc_node *n_ptr);
+void tipc_node_link_down(struct tipc_node *n_ptr, int bearer_id);
+void tipc_node_link_up(struct tipc_node *n_ptr, int bearer_id);
+bool tipc_node_is_up(struct tipc_node *n);
 int tipc_node_get_linkname(struct net *net, u32 bearer_id, u32 node,
 			   char *linkname, size_t len);
 void tipc_node_unlock(struct tipc_node *node);
@@ -165,20 +167,28 @@ static inline bool tipc_node_blocked(struct tipc_node *node)
 		TIPC_NOTIFY_NODE_DOWN | TIPC_WAIT_OWN_LINKS_DOWN));
 }
 
-static inline uint tipc_node_get_mtu(struct net *net, u32 addr, u32 selector)
+static inline struct tipc_link *node_active_link(struct tipc_node *n, int sel)
 {
-	struct tipc_node *node;
-	u32 mtu;
+	struct tipc_link_entry *le = n->active_links[sel & 1];
 
-	node = tipc_node_find(net, addr);
+	if (likely(le))
+		return le->link;
+	return NULL;
+}
 
-	if (likely(node)) {
-		mtu = node->act_mtus[selector & 1];
-		tipc_node_put(node);
-	} else {
-		mtu = MAX_MSG_SIZE;
-	}
+static inline uint tipc_node_get_mtu(struct net *net, u32 addr, u32 selector)
+{
+	struct tipc_node *n;
+	struct tipc_link_entry *le;
+	unsigned int mtu = MAX_MSG_SIZE;
 
+	n = tipc_node_find(net, addr);
+	if (unlikely(!n))
+		return mtu;
+	le = n->active_links[selector & 1];
+	if (likely(le))
+		mtu = le->mtu;
+	tipc_node_put(n);
 	return mtu;
 }