1 files changed, 843 insertions, 0 deletions

diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c
new file mode 100644
index 000000000..1d90f3912
--- /dev/null
+++ b/net/tipc/monitor.c
@@ -0,0 +1,843 @@
+/*
+ * net/tipc/monitor.c
+ *
+ * Copyright (c) 2016, Ericsson AB
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <net/genetlink.h>
+#include "core.h"
+#include "addr.h"
+#include "monitor.h"
+#include "bearer.h"
+
+#define MAX_MON_DOMAIN       64
+#define MON_TIMEOUT          120000
+#define MAX_PEER_DOWN_EVENTS 4
+
+/* struct tipc_mon_domain: domain record to be transferred between peers
+ * @len: actual size of domain record
+ * @gen: current generation of sender's domain
+ * @ack_gen: most recent generation of self's domain acked by peer
+ * @member_cnt: number of domain member nodes described in this record
+ * @up_map: bit map indicating which of the members the sender considers up
+ * @members: identity of the domain members
+ */
+struct tipc_mon_domain {
+	u16 len;
+	u16 gen;
+	u16 ack_gen;
+	u16 member_cnt;
+	u64 up_map;
+	u32 members[MAX_MON_DOMAIN];
+};
+
+/* struct tipc_peer: state of a peer node and its domain
+ * @addr: tipc node identity of peer
+ * @head_map: shows which other nodes currently consider peer 'up'
+ * @domain: most recent domain record from peer
+ * @hash: position in hashed lookup list
+ * @list: position in linked list, in circular ascending order by 'addr'
+ * @applied: number of reported domain members applied on this monitor list
+ * @is_up: peer is up as seen from this node
+ * @is_head: peer is assigned domain head as seen from this node
+ * @is_local: peer is in local domain and should be continuously monitored
+ * @down_cnt: - numbers of other peers which have reported this on lost
+ */
+struct tipc_peer {
+	u32 addr;
+	struct tipc_mon_domain *domain;
+	struct hlist_node hash;
+	struct list_head list;
+	u8 applied;
+	u8 down_cnt;
+	bool is_up;
+	bool is_head;
+	bool is_local;
+};
+
+struct tipc_monitor {
+	struct hlist_head peers[NODE_HTABLE_SIZE];
+	int peer_cnt;
+	struct tipc_peer *self;
+	rwlock_t lock;
+	struct tipc_mon_domain cache;
+	u16 list_gen;
+	u16 dom_gen;
+	struct net *net;
+	struct timer_list timer;
+	unsigned long timer_intv;
+};
+
+static struct tipc_monitor *tipc_monitor(struct net *net, int bearer_id)
+{
+	return tipc_net(net)->monitors[bearer_id];
+}
+
+const int tipc_max_domain_size = sizeof(struct tipc_mon_domain);
+
+/* dom_rec_len(): actual length of domain record for transport
+ */
+static int dom_rec_len(struct tipc_mon_domain *dom, u16 mcnt)
+{
+	return ((void *)&dom->members - (void *)dom) + (mcnt * sizeof(u32));
+}
+
+/* dom_size() : calculate size of own domain based on number of peers
+ */
+static int dom_size(int peers)
+{
+	int i = 0;
+
+	while ((i * i) < peers)
+		i++;
+	return i < MAX_MON_DOMAIN ? i : MAX_MON_DOMAIN;
+}
+
+static void map_set(u64 *up_map, int i, unsigned int v)
+{
+	*up_map &= ~(1ULL << i);
+	*up_map |= ((u64)v << i);
+}
+
+static int map_get(u64 up_map, int i)
+{
+	return (up_map & (1ULL << i)) >> i;
+}
+
+static struct tipc_peer *peer_prev(struct tipc_peer *peer)
+{
+	return list_last_entry(&peer->list, struct tipc_peer, list);
+}
+
+static struct tipc_peer *peer_nxt(struct tipc_peer *peer)
+{
+	return list_first_entry(&peer->list, struct tipc_peer, list);
+}
+
+static struct tipc_peer *peer_head(struct tipc_peer *peer)
+{
+	while (!peer->is_head)
+		peer = peer_prev(peer);
+	return peer;
+}
+
+static struct tipc_peer *get_peer(struct tipc_monitor *mon, u32 addr)
+{
+	struct tipc_peer *peer;
+	unsigned int thash = tipc_hashfn(addr);
+
+	hlist_for_each_entry(peer, &mon->peers[thash], hash) {
+		if (peer->addr == addr)
+			return peer;
+	}
+	return NULL;
+}
+
+static struct tipc_peer *get_self(struct net *net, int bearer_id)
+{
+	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
+
+	return mon->self;
+}
+
+static inline bool tipc_mon_is_active(struct net *net, struct tipc_monitor *mon)
+{
+	struct tipc_net *tn = tipc_net(net);
+
+	return mon->peer_cnt > tn->mon_threshold;
+}
+
+/* mon_identify_lost_members() : - identify amd mark potentially lost members
+ */
+static void mon_identify_lost_members(struct tipc_peer *peer,
+				      struct tipc_mon_domain *dom_bef,
+				      int applied_bef)
+{
+	struct tipc_peer *member = peer;
+	struct tipc_mon_domain *dom_aft = peer->domain;
+	int applied_aft = peer->applied;
+	int i;
+
+	for (i = 0; i < applied_bef; i++) {
+		member = peer_nxt(member);
+
+		/* Do nothing if self or peer already see member as down */
+		if (!member->is_up || !map_get(dom_bef->up_map, i))
+			continue;
+
+		/* Loss of local node must be detected by active probing */
+		if (member->is_local)
+			continue;
+
+		/* Start probing if member was removed from applied domain */
+		if (!applied_aft || (applied_aft < i)) {
+			member->down_cnt = 1;
+			continue;
+		}
+
+		/* Member loss is confirmed if it is still in applied domain */
+		if (!map_get(dom_aft->up_map, i))
+			member->down_cnt++;
+	}
+}
+
+/* mon_apply_domain() : match a peer's domain record against monitor list
+ */
+static void mon_apply_domain(struct tipc_monitor *mon,
+			     struct tipc_peer *peer)
+{
+	struct tipc_mon_domain *dom = peer->domain;
+	struct tipc_peer *member;
+	u32 addr;
+	int i;
+
+	if (!dom || !peer->is_up)
+		return;
+
+	/* Scan across domain members and match against monitor list */
+	peer->applied = 0;
+	member = peer_nxt(peer);
+	for (i = 0; i < dom->member_cnt; i++) {
+		addr = dom->members[i];
+		if (addr != member->addr)
+			return;
+		peer->applied++;
+		member = peer_nxt(member);
+	}
+}
+
+/* mon_update_local_domain() : update after peer addition/removal/up/down
+ */
+static void mon_update_local_domain(struct tipc_monitor *mon)
+{
+	struct tipc_peer *self = mon->self;
+	struct tipc_mon_domain *cache = &mon->cache;
+	struct tipc_mon_domain *dom = self->domain;
+	struct tipc_peer *peer = self;
+	u64 prev_up_map = dom->up_map;
+	u16 member_cnt, i;
+	bool diff;
+
+	/* Update local domain size based on current size of cluster */
+	member_cnt = dom_size(mon->peer_cnt) - 1;
+	self->applied = member_cnt;
+
+	/* Update native and cached outgoing local domain records */
+	dom->len = dom_rec_len(dom, member_cnt);
+	diff = dom->member_cnt != member_cnt;
+	dom->member_cnt = member_cnt;
+	for (i = 0; i < member_cnt; i++) {
+		peer = peer_nxt(peer);
+		diff |= dom->members[i] != peer->addr;
+		dom->members[i] = peer->addr;
+		map_set(&dom->up_map, i, peer->is_up);
+		cache->members[i] = htonl(peer->addr);
+	}
+	diff |= dom->up_map != prev_up_map;
+	if (!diff)
+		return;
+	dom->gen = ++mon->dom_gen;
+	cache->len = htons(dom->len);
+	cache->gen = htons(dom->gen);
+	cache->member_cnt = htons(member_cnt);
+	cache->up_map = cpu_to_be64(dom->up_map);
+	mon_apply_domain(mon, self);
+}
+
+/* mon_update_neighbors() : update preceding neighbors of added/removed peer
+ */
+static void mon_update_neighbors(struct tipc_monitor *mon,
+				 struct tipc_peer *peer)
+{
+	int dz, i;
+
+	dz = dom_size(mon->peer_cnt);
+	for (i = 0; i < dz; i++) {
+		mon_apply_domain(mon, peer);
+		peer = peer_prev(peer);
+	}
+}
+
+/* mon_assign_roles() : reassign peer roles after a network change
+ * The monitor list is consistent at this stage; i.e., each peer is monitoring
+ * a set of domain members as matched between domain record and the monitor list
+ */
+static void mon_assign_roles(struct tipc_monitor *mon, struct tipc_peer *head)
+{
+	struct tipc_peer *peer = peer_nxt(head);
+	struct tipc_peer *self = mon->self;
+	int i = 0;
+
+	for (; peer != self; peer = peer_nxt(peer)) {
+		peer->is_local = false;
+
+		/* Update domain member */
+		if (i++ < head->applied) {
+			peer->is_head = false;
+			if (head == self)
+				peer->is_local = true;
+			continue;
+		}
+		/* Assign next domain head */
+		if (!peer->is_up)
+			continue;
+		if (peer->is_head)
+			break;
+		head = peer;
+		head->is_head = true;
+		i = 0;
+	}
+	mon->list_gen++;
+}
+
+void tipc_mon_remove_peer(struct net *net, u32 addr, int bearer_id)
+{
+	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
+	struct tipc_peer *self;
+	struct tipc_peer *peer, *prev, *head;
+
+	if (!mon)
+		return;
+
+	self = get_self(net, bearer_id);
+	write_lock_bh(&mon->lock);
+	peer = get_peer(mon, addr);
+	if (!peer)
+		goto exit;
+	prev = peer_prev(peer);
+	list_del(&peer->list);
+	hlist_del(&peer->hash);
+	kfree(peer->domain);
+	kfree(peer);
+	mon->peer_cnt--;
+	head = peer_head(prev);
+	if (head == self)
+		mon_update_local_domain(mon);
+	mon_update_neighbors(mon, prev);
+
+	/* Revert to full-mesh monitoring if we reach threshold */
+	if (!tipc_mon_is_active(net, mon)) {
+		list_for_each_entry(peer, &self->list, list) {
+			kfree(peer->domain);
+			peer->domain = NULL;
+			peer->applied = 0;
+		}
+	}
+	mon_assign_roles(mon, head);
+exit:
+	write_unlock_bh(&mon->lock);
+}
+
+static bool tipc_mon_add_peer(struct tipc_monitor *mon, u32 addr,
+			      struct tipc_peer **peer)
+{
+	struct tipc_peer *self = mon->self;
+	struct tipc_peer *cur, *prev, *p;
+
+	p = kzalloc(sizeof(*p), GFP_ATOMIC);
+	*peer = p;
+	if (!p)
+		return false;
+	p->addr = addr;
+
+	/* Add new peer to lookup list */
+	INIT_LIST_HEAD(&p->list);
+	hlist_add_head(&p->hash, &mon->peers[tipc_hashfn(addr)]);
+
+	/* Sort new peer into iterator list, in ascending circular order */
+	prev = self;
+	list_for_each_entry(cur, &self->list, list) {
+		if ((addr > prev->addr) && (addr < cur->addr))
+			break;
+		if (((addr < cur->addr) || (addr > prev->addr)) &&
+		    (prev->addr > cur->addr))
+			break;
+		prev = cur;
+	}
+	list_add_tail(&p->list, &cur->list);
+	mon->peer_cnt++;
+	mon_update_neighbors(mon, p);
+	return true;
+}
+
+void tipc_mon_peer_up(struct net *net, u32 addr, int bearer_id)
+{
+	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
+	struct tipc_peer *self = get_self(net, bearer_id);
+	struct tipc_peer *peer, *head;
+
+	write_lock_bh(&mon->lock);
+	peer = get_peer(mon, addr);
+	if (!peer && !tipc_mon_add_peer(mon, addr, &peer))
+		goto exit;
+	peer->is_up = true;
+	head = peer_head(peer);
+	if (head == self)
+		mon_update_local_domain(mon);
+	mon_assign_roles(mon, head);
+exit:
+	write_unlock_bh(&mon->lock);
+}
+
+void tipc_mon_peer_down(struct net *net, u32 addr, int bearer_id)
+{
+	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
+	struct tipc_peer *self;
+	struct tipc_peer *peer, *head;
+	struct tipc_mon_domain *dom;
+	int applied;
+
+	if (!mon)
+		return;
+
+	self = get_self(net, bearer_id);
+	write_lock_bh(&mon->lock);
+	peer = get_peer(mon, addr);
+	if (!peer) {
+		pr_warn("Mon: unknown link %x/%u DOWN\n", addr, bearer_id);
+		goto exit;
+	}
+	applied = peer->applied;
+	peer->applied = 0;
+	dom = peer->domain;
+	peer->domain = NULL;
+	if (peer->is_head)
+		mon_identify_lost_members(peer, dom, applied);
+	kfree(dom);
+	peer->is_up = false;
+	peer->is_head = false;
+	peer->is_local = false;
+	peer->down_cnt = 0;
+	head = peer_head(peer);
+	if (head == self)
+		mon_update_local_domain(mon);
+	mon_assign_roles(mon, head);
+exit:
+	write_unlock_bh(&mon->lock);
+}
+
+/* tipc_mon_rcv - process monitor domain event message
+ */
+void tipc_mon_rcv(struct net *net, void *data, u16 dlen, u32 addr,
+		  struct tipc_mon_state *state, int bearer_id)
+{
+	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
+	struct tipc_mon_domain *arrv_dom = data;
+	struct tipc_mon_domain dom_bef;
+	struct tipc_mon_domain *dom;
+	struct tipc_peer *peer;
+	u16 new_member_cnt = ntohs(arrv_dom->member_cnt);
+	int new_dlen = dom_rec_len(arrv_dom, new_member_cnt);
+	u16 new_gen = ntohs(arrv_dom->gen);
+	u16 acked_gen = ntohs(arrv_dom->ack_gen);
+	bool probing = state->probing;
+	int i, applied_bef;
+
+	state->probing = false;
+
+	/* Sanity check received domain record */
+	if (new_member_cnt > MAX_MON_DOMAIN)
+		return;
+	if (dlen < dom_rec_len(arrv_dom, 0))
+		return;
+	if (dlen != dom_rec_len(arrv_dom, new_member_cnt))
+		return;
+	if ((dlen < new_dlen) || ntohs(arrv_dom->len) != new_dlen)
+		return;
+
+	/* Synch generation numbers with peer if link just came up */
+	if (!state->synched) {
+		state->peer_gen = new_gen - 1;
+		state->acked_gen = acked_gen;
+		state->synched = true;
+	}
+
+	if (more(acked_gen, state->acked_gen))
+		state->acked_gen = acked_gen;
+
+	/* Drop duplicate unless we are waiting for a probe response */
+	if (!more(new_gen, state->peer_gen) && !probing)
+		return;
+
+	write_lock_bh(&mon->lock);
+	peer = get_peer(mon, addr);
+	if (!peer || !peer->is_up)
+		goto exit;
+
+	/* Peer is confirmed, stop any ongoing probing */
+	peer->down_cnt = 0;
+
+	/* Task is done for duplicate record */
+	if (!more(new_gen, state->peer_gen))
+		goto exit;
+
+	state->peer_gen = new_gen;
+
+	/* Cache current domain record for later use */
+	dom_bef.member_cnt = 0;
+	dom = peer->domain;
+	if (dom)
+		memcpy(&dom_bef, dom, dom->len);
+
+	/* Transform and store received domain record */
+	if (!dom || (dom->len < new_dlen)) {
+		kfree(dom);
+		dom = kmalloc(new_dlen, GFP_ATOMIC);
+		peer->domain = dom;
+		if (!dom)
+			goto exit;
+	}
+	dom->len = new_dlen;
+	dom->gen = new_gen;
+	dom->member_cnt = new_member_cnt;
+	dom->up_map = be64_to_cpu(arrv_dom->up_map);
+	for (i = 0; i < new_member_cnt; i++)
+		dom->members[i] = ntohl(arrv_dom->members[i]);
+
+	/* Update peers affected by this domain record */
+	applied_bef = peer->applied;
+	mon_apply_domain(mon, peer);
+	mon_identify_lost_members(peer, &dom_bef, applied_bef);
+	mon_assign_roles(mon, peer_head(peer));
+exit:
+	write_unlock_bh(&mon->lock);
+}
+
+void tipc_mon_prep(struct net *net, void *data, int *dlen,
+		   struct tipc_mon_state *state, int bearer_id)
+{
+	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
+	struct tipc_mon_domain *dom = data;
+	u16 gen = mon->dom_gen;
+	u16 len;
+
+	/* Send invalid record if not active */
+	if (!tipc_mon_is_active(net, mon)) {
+		dom->len = 0;
+		return;
+	}
+
+	/* Send only a dummy record with ack if peer has acked our last sent */
+	if (likely(state->acked_gen == gen)) {
+		len = dom_rec_len(dom, 0);
+		*dlen = len;
+		dom->len = htons(len);
+		dom->gen = htons(gen);
+		dom->ack_gen = htons(state->peer_gen);
+		dom->member_cnt = 0;
+		return;
+	}
+	/* Send the full record */
+	read_lock_bh(&mon->lock);
+	len = ntohs(mon->cache.len);
+	*dlen = len;
+	memcpy(data, &mon->cache, len);
+	read_unlock_bh(&mon->lock);
+	dom->ack_gen = htons(state->peer_gen);
+}
+
+void tipc_mon_get_state(struct net *net, u32 addr,
+			struct tipc_mon_state *state,
+			int bearer_id)
+{
+	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
+	struct tipc_peer *peer;
+
+	if (!tipc_mon_is_active(net, mon)) {
+		state->probing = false;
+		state->monitoring = true;
+		return;
+	}
+
+	/* Used cached state if table has not changed */
+	if (!state->probing &&
+	    (state->list_gen == mon->list_gen) &&
+	    (state->acked_gen == mon->dom_gen))
+		return;
+
+	read_lock_bh(&mon->lock);
+	peer = get_peer(mon, addr);
+	if (peer) {
+		state->probing = state->acked_gen != mon->dom_gen;
+		state->probing |= peer->down_cnt;
+		state->reset |= peer->down_cnt >= MAX_PEER_DOWN_EVENTS;
+		state->monitoring = peer->is_local;
+		state->monitoring |= peer->is_head;
+		state->list_gen = mon->list_gen;
+	}
+	read_unlock_bh(&mon->lock);
+}
+
+static void mon_timeout(struct timer_list *t)
+{
+	struct tipc_monitor *mon = from_timer(mon, t, timer);
+	struct tipc_peer *self;
+	int best_member_cnt = dom_size(mon->peer_cnt) - 1;
+
+	write_lock_bh(&mon->lock);
+	self = mon->self;
+	if (self && (best_member_cnt != self->applied)) {
+		mon_update_local_domain(mon);
+		mon_assign_roles(mon, self);
+	}
+	write_unlock_bh(&mon->lock);
+	mod_timer(&mon->timer, jiffies + mon->timer_intv);
+}
+
+int tipc_mon_create(struct net *net, int bearer_id)
+{
+	struct tipc_net *tn = tipc_net(net);
+	struct tipc_monitor *mon;
+	struct tipc_peer *self;
+	struct tipc_mon_domain *dom;
+
+	if (tn->monitors[bearer_id])
+		return 0;
+
+	mon = kzalloc(sizeof(*mon), GFP_ATOMIC);
+	self = kzalloc(sizeof(*self), GFP_ATOMIC);
+	dom = kzalloc(sizeof(*dom), GFP_ATOMIC);
+	if (!mon || !self || !dom) {
+		kfree(mon);
+		kfree(self);
+		kfree(dom);
+		return -ENOMEM;
+	}
+	tn->monitors[bearer_id] = mon;
+	rwlock_init(&mon->lock);
+	mon->net = net;
+	mon->peer_cnt = 1;
+	mon->self = self;
+	self->domain = dom;
+	self->addr = tipc_own_addr(net);
+	self->is_up = true;
+	self->is_head = true;
+	INIT_LIST_HEAD(&self->list);
+	timer_setup(&mon->timer, mon_timeout, 0);
+	mon->timer_intv = msecs_to_jiffies(MON_TIMEOUT + (tn->random & 0xffff));
+	mod_timer(&mon->timer, jiffies + mon->timer_intv);
+	return 0;
+}
+
+void tipc_mon_delete(struct net *net, int bearer_id)
+{
+	struct tipc_net *tn = tipc_net(net);
+	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
+	struct tipc_peer *self;
+	struct tipc_peer *peer, *tmp;
+
+	if (!mon)
+		return;
+
+	self = get_self(net, bearer_id);
+	write_lock_bh(&mon->lock);
+	tn->monitors[bearer_id] = NULL;
+	list_for_each_entry_safe(peer, tmp, &self->list, list) {
+		list_del(&peer->list);
+		hlist_del(&peer->hash);
+		kfree(peer->domain);
+		kfree(peer);
+	}
+	mon->self = NULL;
+	write_unlock_bh(&mon->lock);
+	del_timer_sync(&mon->timer);
+	kfree(self->domain);
+	kfree(self);
+	kfree(mon);
+}
+
+void tipc_mon_reinit_self(struct net *net)
+{
+	struct tipc_monitor *mon;
+	int bearer_id;
+
+	for (bearer_id = 0; bearer_id < MAX_BEARERS; bearer_id++) {
+		mon = tipc_monitor(net, bearer_id);
+		if (!mon)
+			continue;
+		write_lock_bh(&mon->lock);
+		mon->self->addr = tipc_own_addr(net);
+		write_unlock_bh(&mon->lock);
+	}
+}
+
+int tipc_nl_monitor_set_threshold(struct net *net, u32 cluster_size)
+{
+	struct tipc_net *tn = tipc_net(net);
+
+	if (cluster_size > TIPC_CLUSTER_SIZE)
+		return -EINVAL;
+
+	tn->mon_threshold = cluster_size;
+
+	return 0;
+}
+
+int tipc_nl_monitor_get_threshold(struct net *net)
+{
+	struct tipc_net *tn = tipc_net(net);
+
+	return tn->mon_threshold;
+}
+
+static int __tipc_nl_add_monitor_peer(struct tipc_peer *peer,
+				      struct tipc_nl_msg *msg)
+{
+	struct tipc_mon_domain *dom = peer->domain;
+	struct nlattr *attrs;
+	void *hdr;
+
+	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
+			  NLM_F_MULTI, TIPC_NL_MON_PEER_GET);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	attrs = nla_nest_start_noflag(msg->skb, TIPC_NLA_MON_PEER);
+	if (!attrs)
+		goto msg_full;
+
+	if (nla_put_u32(msg->skb, TIPC_NLA_MON_PEER_ADDR, peer->addr))
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_MON_PEER_APPLIED, peer->applied))
+		goto attr_msg_full;
+
+	if (peer->is_up)
+		if (nla_put_flag(msg->skb, TIPC_NLA_MON_PEER_UP))
+			goto attr_msg_full;
+	if (peer->is_local)
+		if (nla_put_flag(msg->skb, TIPC_NLA_MON_PEER_LOCAL))
+			goto attr_msg_full;
+	if (peer->is_head)
+		if (nla_put_flag(msg->skb, TIPC_NLA_MON_PEER_HEAD))
+			goto attr_msg_full;
+
+	if (dom) {
+		if (nla_put_u32(msg->skb, TIPC_NLA_MON_PEER_DOMGEN, dom->gen))
+			goto attr_msg_full;
+		if (nla_put_u64_64bit(msg->skb, TIPC_NLA_MON_PEER_UPMAP,
+				      dom->up_map, TIPC_NLA_MON_PEER_PAD))
+			goto attr_msg_full;
+		if (nla_put(msg->skb, TIPC_NLA_MON_PEER_MEMBERS,
+			    dom->member_cnt * sizeof(u32), &dom->members))
+			goto attr_msg_full;
+	}
+
+	nla_nest_end(msg->skb, attrs);
+	genlmsg_end(msg->skb, hdr);
+	return 0;
+
+attr_msg_full:
+	nla_nest_cancel(msg->skb, attrs);
+msg_full:
+	genlmsg_cancel(msg->skb, hdr);
+
+	return -EMSGSIZE;
+}
+
+int tipc_nl_add_monitor_peer(struct net *net, struct tipc_nl_msg *msg,
+			     u32 bearer_id, u32 *prev_node)
+{
+	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
+	struct tipc_peer *peer;
+
+	if (!mon)
+		return -EINVAL;
+
+	read_lock_bh(&mon->lock);
+	peer = mon->self;
+	do {
+		if (*prev_node) {
+			if (peer->addr == *prev_node)
+				*prev_node = 0;
+			else
+				continue;
+		}
+		if (__tipc_nl_add_monitor_peer(peer, msg)) {
+			*prev_node = peer->addr;
+			read_unlock_bh(&mon->lock);
+			return -EMSGSIZE;
+		}
+	} while ((peer = peer_nxt(peer)) != mon->self);
+	read_unlock_bh(&mon->lock);
+
+	return 0;
+}
+
+int __tipc_nl_add_monitor(struct net *net, struct tipc_nl_msg *msg,
+			  u32 bearer_id)
+{
+	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
+	char bearer_name[TIPC_MAX_BEARER_NAME];
+	struct nlattr *attrs;
+	void *hdr;
+	int ret;
+
+	ret = tipc_bearer_get_name(net, bearer_name, bearer_id);
+	if (ret || !mon)
+		return 0;
+
+	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
+			  NLM_F_MULTI, TIPC_NL_MON_GET);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	attrs = nla_nest_start_noflag(msg->skb, TIPC_NLA_MON);
+	if (!attrs)
+		goto msg_full;
+
+	read_lock_bh(&mon->lock);
+	if (nla_put_u32(msg->skb, TIPC_NLA_MON_REF, bearer_id))
+		goto attr_msg_full;
+	if (tipc_mon_is_active(net, mon))
+		if (nla_put_flag(msg->skb, TIPC_NLA_MON_ACTIVE))
+			goto attr_msg_full;
+	if (nla_put_string(msg->skb, TIPC_NLA_MON_BEARER_NAME, bearer_name))
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_MON_PEERCNT, mon->peer_cnt))
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_MON_LISTGEN, mon->list_gen))
+		goto attr_msg_full;
+
+	read_unlock_bh(&mon->lock);
+	nla_nest_end(msg->skb, attrs);
+	genlmsg_end(msg->skb, hdr);
+
+	return 0;
+
+attr_msg_full:
+	read_unlock_bh(&mon->lock);
+	nla_nest_cancel(msg->skb, attrs);
+msg_full:
+	genlmsg_cancel(msg->skb, hdr);
+
+	return -EMSGSIZE;
+}