1 files changed, 740 insertions, 798 deletions

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 59f64c596233..8b80ca0cd65f 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -63,41 +63,49 @@
 
 #define NEEDED_RMEM (4*1024*1024)
 
-/* Number of messages to send before rescheduling */
-#define MAX_SEND_MSG_COUNT 25
-#define DLM_SHUTDOWN_WAIT_TIMEOUT msecs_to_jiffies(10000)
-
 struct connection {
 	struct socket *sock;	/* NULL if not connected */
 	uint32_t nodeid;	/* So we know who we are in the list */
-	struct mutex sock_mutex;
+	/* this semaphore is used to allow parallel recv/send in read
+	 * lock mode. When we release a sock we need to held the write lock.
+	 *
+	 * However this is locking code and not nice. When we remove the
+	 * othercon handling we can look into other mechanism to synchronize
+	 * io handling to call sock_release() at the right time.
+	 */
+	struct rw_semaphore sock_lock;
 	unsigned long flags;
-#define CF_READ_PENDING 1
-#define CF_WRITE_PENDING 2
-#define CF_INIT_PENDING 4
+#define CF_APP_LIMITED 0
+#define CF_RECV_PENDING 1
+#define CF_SEND_PENDING 2
+#define CF_RECV_INTR 3
+#define CF_IO_STOP 4
 #define CF_IS_OTHERCON 5
-#define CF_CLOSE 6
-#define CF_APP_LIMITED 7
-#define CF_CLOSING 8
-#define CF_SHUTDOWN 9
-#define CF_CONNECTED 10
-#define CF_RECONNECT 11
-#define CF_DELAY_CONNECT 12
-#define CF_EOF 13
 	struct list_head writequeue;  /* List of outgoing writequeue_entries */
 	spinlock_t writequeue_lock;
-	atomic_t writequeue_cnt;
 	int retries;
-#define MAX_CONNECT_RETRIES 3
 	struct hlist_node list;
+	/* due some connect()/accept() races we currently have this cross over
+	 * connection attempt second connection for one node.
+	 *
+	 * There is a solution to avoid the race by introducing a connect
+	 * rule as e.g. our_nodeid > nodeid_to_connect who is allowed to
+	 * connect. Otherside can connect but will only be considered that
+	 * the other side wants to have a reconnect.
+	 *
+	 * However changing to this behaviour will break backwards compatible.
+	 * In a DLM protocol major version upgrade we should remove this!
+	 */
 	struct connection *othercon;
-	struct connection *sendcon;
-	struct work_struct rwork; /* Receive workqueue */
-	struct work_struct swork; /* Send workqueue */
-	wait_queue_head_t shutdown_wait; /* wait for graceful shutdown */
-	unsigned char *rx_buf;
-	int rx_buflen;
+	struct work_struct rwork; /* receive worker */
+	struct work_struct swork; /* send worker */
+	unsigned char rx_leftover_buf[DLM_MAX_SOCKET_BUFSIZE];
 	int rx_leftover;
+	int mark;
+	int addr_count;
+	int curr_addr_index;
+	struct sockaddr_storage addr[DLM_MAX_ADDR_COUNT];
+	spinlock_t addrs_lock;
 	struct rcu_head rcu;
 };
 #define sock2con(x) ((struct connection *)(x)->sk_user_data)
@@ -136,13 +144,12 @@ struct dlm_msg {
 	struct kref ref;
 };
 
-struct dlm_node_addr {
-	struct list_head list;
+struct processqueue_entry {
+	unsigned char *buf;
 	int nodeid;
-	int mark;
-	int addr_count;
-	int curr_addr_index;
-	struct sockaddr_storage *addr[DLM_MAX_ADDR_COUNT];
+	int buflen;
+
+	struct list_head list;
 };
 
 struct dlm_proto_ops {
@@ -157,10 +164,6 @@ struct dlm_proto_ops {
 	int (*listen_validate)(void);
 	void (*listen_sockopts)(struct socket *sock);
 	int (*listen_bind)(struct socket *sock);
-	/* What to do to shutdown */
-	void (*shutdown_action)(struct connection *con);
-	/* What to do to eof check */
-	bool (*eof_condition)(struct connection *con);
 };
 
 static struct listen_sock_callbacks {
@@ -170,17 +173,13 @@ static struct listen_sock_callbacks {
 	void (*sk_write_space)(struct sock *);
 } listen_sock;
 
-static LIST_HEAD(dlm_node_addrs);
-static DEFINE_SPINLOCK(dlm_node_addrs_spin);
-
 static struct listen_connection listen_con;
-static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
+static struct sockaddr_storage dlm_local_addr[DLM_MAX_ADDR_COUNT];
 static int dlm_local_count;
-int dlm_allow_conn;
 
 /* Work queues */
-static struct workqueue_struct *recv_workqueue;
-static struct workqueue_struct *send_workqueue;
+static struct workqueue_struct *io_workqueue;
+static struct workqueue_struct *process_workqueue;
 
 static struct hlist_head connection_hash[CONN_HASH_SIZE];
 static DEFINE_SPINLOCK(connections_lock);
@@ -188,8 +187,45 @@ DEFINE_STATIC_SRCU(connections_srcu);
 
 static const struct dlm_proto_ops *dlm_proto_ops;
 
+#define DLM_IO_SUCCESS 0
+#define DLM_IO_END 1
+#define DLM_IO_EOF 2
+#define DLM_IO_RESCHED 3
+
 static void process_recv_sockets(struct work_struct *work);
 static void process_send_sockets(struct work_struct *work);
+static void process_dlm_messages(struct work_struct *work);
+
+static DECLARE_WORK(process_work, process_dlm_messages);
+static DEFINE_SPINLOCK(processqueue_lock);
+static bool process_dlm_messages_pending;
+static LIST_HEAD(processqueue);
+
+bool dlm_lowcomms_is_running(void)
+{
+	return !!listen_con.sock;
+}
+
+static void lowcomms_queue_swork(struct connection *con)
+{
+	assert_spin_locked(&con->writequeue_lock);
+
+	if (!test_bit(CF_IO_STOP, &con->flags) &&
+	    !test_bit(CF_APP_LIMITED, &con->flags) &&
+	    !test_and_set_bit(CF_SEND_PENDING, &con->flags))
+		queue_work(io_workqueue, &con->swork);
+}
+
+static void lowcomms_queue_rwork(struct connection *con)
+{
+#ifdef CONFIG_LOCKDEP
+	WARN_ON_ONCE(!lockdep_sock_is_held(con->sock->sk));
+#endif
+
+	if (!test_bit(CF_IO_STOP, &con->flags) &&
+	    !test_and_set_bit(CF_RECV_PENDING, &con->flags))
+		queue_work(io_workqueue, &con->rwork);
+}
 
 static void writequeue_entry_ctor(void *data)
 {
@@ -214,15 +250,12 @@ static struct writequeue_entry *con_next_wq(struct connection *con)
 {
 	struct writequeue_entry *e;
 
-	if (list_empty(&con->writequeue))
-		return NULL;
-
-	e = list_first_entry(&con->writequeue, struct writequeue_entry,
-			     list);
+	e = list_first_entry_or_null(&con->writequeue, struct writequeue_entry,
+				     list);
 	/* if len is zero nothing is to send, if there are users filling
 	 * buffers we wait until the users are done so we can send more.
 	 */
-	if (e->users || e->len == 0)
+	if (!e || e->users || e->len == 0)
 		return NULL;
 
 	return e;
@@ -240,28 +273,15 @@ static struct connection *__find_con(int nodeid, int r)
 	return NULL;
 }
 
-static bool tcp_eof_condition(struct connection *con)
-{
-	return atomic_read(&con->writequeue_cnt);
-}
-
-static int dlm_con_init(struct connection *con, int nodeid)
+static void dlm_con_init(struct connection *con, int nodeid)
 {
-	con->rx_buflen = dlm_config.ci_buffer_size;
-	con->rx_buf = kmalloc(con->rx_buflen, GFP_NOFS);
-	if (!con->rx_buf)
-		return -ENOMEM;
-
 	con->nodeid = nodeid;
-	mutex_init(&con->sock_mutex);
+	init_rwsem(&con->sock_lock);
 	INIT_LIST_HEAD(&con->writequeue);
 	spin_lock_init(&con->writequeue_lock);
-	atomic_set(&con->writequeue_cnt, 0);
 	INIT_WORK(&con->swork, process_send_sockets);
 	INIT_WORK(&con->rwork, process_recv_sockets);
-	init_waitqueue_head(&con->shutdown_wait);
-
-	return 0;
+	spin_lock_init(&con->addrs_lock);
 }
 
 /*
@@ -271,7 +291,7 @@ static int dlm_con_init(struct connection *con, int nodeid)
 static struct connection *nodeid2con(int nodeid, gfp_t alloc)
 {
 	struct connection *con, *tmp;
-	int r, ret;
+	int r;
 
 	r = nodeid_hash(nodeid);
 	con = __find_con(nodeid, r);
@@ -282,11 +302,7 @@ static struct connection *nodeid2con(int nodeid, gfp_t alloc)
 	if (!con)
 		return NULL;
 
-	ret = dlm_con_init(con, nodeid);
-	if (ret) {
-		kfree(con);
-		return NULL;
-	}
+	dlm_con_init(con, nodeid);
 
 	spin_lock(&connections_lock);
 	/* Because multiple workqueues/threads calls this function it can
@@ -298,7 +314,6 @@ static struct connection *nodeid2con(int nodeid, gfp_t alloc)
 	tmp = __find_con(nodeid, r);
 	if (tmp) {
 		spin_unlock(&connections_lock);
-		kfree(con->rx_buf);
 		kfree(con);
 		return tmp;
 	}
@@ -309,29 +324,6 @@ static struct connection *nodeid2con(int nodeid, gfp_t alloc)
 	return con;
 }
 
-/* Loop round all connections */
-static void foreach_conn(void (*conn_func)(struct connection *c))
-{
-	int i;
-	struct connection *con;
-
-	for (i = 0; i < CONN_HASH_SIZE; i++) {
-		hlist_for_each_entry_rcu(con, &connection_hash[i], list)
-			conn_func(con);
-	}
-}
-
-static struct dlm_node_addr *find_node_addr(int nodeid)
-{
-	struct dlm_node_addr *na;
-
-	list_for_each_entry(na, &dlm_node_addrs, list) {
-		if (na->nodeid == nodeid)
-			return na;
-	}
-	return NULL;
-}
-
 static int addr_compare(const struct sockaddr_storage *x,
 			const struct sockaddr_storage *y)
 {
@@ -365,40 +357,47 @@ static int nodeid_to_addr(int nodeid, struct sockaddr_storage *sas_out,
 			  unsigned int *mark)
 {
 	struct sockaddr_storage sas;
-	struct dlm_node_addr *na;
+	struct connection *con;
+	int idx;
 
 	if (!dlm_local_count)
 		return -1;
 
-	spin_lock(&dlm_node_addrs_spin);
-	na = find_node_addr(nodeid);
-	if (na && na->addr_count) {
-		memcpy(&sas, na->addr[na->curr_addr_index],
-		       sizeof(struct sockaddr_storage));
+	idx = srcu_read_lock(&connections_srcu);
+	con = nodeid2con(nodeid, 0);
+	if (!con) {
+		srcu_read_unlock(&connections_srcu, idx);
+		return -ENOENT;
+	}
 
-		if (try_new_addr) {
-			na->curr_addr_index++;
-			if (na->curr_addr_index == na->addr_count)
-				na->curr_addr_index = 0;
-		}
+	spin_lock(&con->addrs_lock);
+	if (!con->addr_count) {
+		spin_unlock(&con->addrs_lock);
+		srcu_read_unlock(&connections_srcu, idx);
+		return -ENOENT;
 	}
-	spin_unlock(&dlm_node_addrs_spin);
 
-	if (!na)
-		return -EEXIST;
+	memcpy(&sas, &con->addr[con->curr_addr_index],
+	       sizeof(struct sockaddr_storage));
 
-	if (!na->addr_count)
-		return -ENOENT;
+	if (try_new_addr) {
+		con->curr_addr_index++;
+		if (con->curr_addr_index == con->addr_count)
+			con->curr_addr_index = 0;
+	}
 
-	*mark = na->mark;
+	*mark = con->mark;
+	spin_unlock(&con->addrs_lock);
 
 	if (sas_out)
 		memcpy(sas_out, &sas, sizeof(struct sockaddr_storage));
 
-	if (!sa_out)
+	if (!sa_out) {
+		srcu_read_unlock(&connections_srcu, idx);
 		return 0;
+	}
 
-	if (dlm_local_addr[0]->ss_family == AF_INET) {
+	if (dlm_local_addr[0].ss_family == AF_INET) {
 		struct sockaddr_in *in4  = (struct sockaddr_in *) &sas;
 		struct sockaddr_in *ret4 = (struct sockaddr_in *) sa_out;
 		ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
@@ -408,43 +407,46 @@ static int nodeid_to_addr(int nodeid, struct sockaddr_storage *sas_out,
 		ret6->sin6_addr = in6->sin6_addr;
 	}
 
+	srcu_read_unlock(&connections_srcu, idx);
 	return 0;
 }
 
 static int addr_to_nodeid(struct sockaddr_storage *addr, int *nodeid,
 			  unsigned int *mark)
 {
-	struct dlm_node_addr *na;
-	int rv = -EEXIST;
-	int addr_i;
-
-	spin_lock(&dlm_node_addrs_spin);
-	list_for_each_entry(na, &dlm_node_addrs, list) {
-		if (!na->addr_count)
-			continue;
-
-		for (addr_i = 0; addr_i < na->addr_count; addr_i++) {
-			if (addr_compare(na->addr[addr_i], addr)) {
-				*nodeid = na->nodeid;
-				*mark = na->mark;
-				rv = 0;
-				goto unlock;
+	struct connection *con;
+	int i, idx, addr_i;
+
+	idx = srcu_read_lock(&connections_srcu);
+	for (i = 0; i < CONN_HASH_SIZE; i++) {
+		hlist_for_each_entry_rcu(con, &connection_hash[i], list) {
+			WARN_ON_ONCE(!con->addr_count);
+
+			spin_lock(&con->addrs_lock);
+			for (addr_i = 0; addr_i < con->addr_count; addr_i++) {
+				if (addr_compare(&con->addr[addr_i], addr)) {
+					*nodeid = con->nodeid;
+					*mark = con->mark;
+					spin_unlock(&con->addrs_lock);
+					srcu_read_unlock(&connections_srcu, idx);
+					return 0;
+				}
 			}
+			spin_unlock(&con->addrs_lock);
 		}
 	}
-unlock:
-	spin_unlock(&dlm_node_addrs_spin);
-	return rv;
+	srcu_read_unlock(&connections_srcu, idx);
+
+	return -ENOENT;
 }
 
-/* caller need to held dlm_node_addrs_spin lock */
-static bool dlm_lowcomms_na_has_addr(const struct dlm_node_addr *na,
-				     const struct sockaddr_storage *addr)
+static bool dlm_lowcomms_con_has_addr(const struct connection *con,
+				      const struct sockaddr_storage *addr)
 {
 	int i;
 
-	for (i = 0; i < na->addr_count; i++) {
-		if (addr_compare(na->addr[i], addr))
+	for (i = 0; i < con->addr_count; i++) {
+		if (addr_compare(&con->addr[i], addr))
 			return true;
 	}
 
@@ -453,118 +455,82 @@ static bool dlm_lowcomms_na_has_addr(const struct dlm_node_addr *na,
 
 int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr, int len)
 {
-	struct sockaddr_storage *new_addr;
-	struct dlm_node_addr *new_node, *na;
-	bool ret;
-
-	new_node = kzalloc(sizeof(struct dlm_node_addr), GFP_NOFS);
-	if (!new_node)
-		return -ENOMEM;
+	struct connection *con;
+	bool ret, idx;
 
-	new_addr = kzalloc(sizeof(struct sockaddr_storage), GFP_NOFS);
-	if (!new_addr) {
-		kfree(new_node);
+	idx = srcu_read_lock(&connections_srcu);
+	con = nodeid2con(nodeid, GFP_NOFS);
+	if (!con) {
+		srcu_read_unlock(&connections_srcu, idx);
 		return -ENOMEM;
 	}
 
-	memcpy(new_addr, addr, len);
-
-	spin_lock(&dlm_node_addrs_spin);
-	na = find_node_addr(nodeid);
-	if (!na) {
-		new_node->nodeid = nodeid;
-		new_node->addr[0] = new_addr;
-		new_node->addr_count = 1;
-		new_node->mark = dlm_config.ci_mark;
-		list_add(&new_node->list, &dlm_node_addrs);
-		spin_unlock(&dlm_node_addrs_spin);
+	spin_lock(&con->addrs_lock);
+	if (!con->addr_count) {
+		memcpy(&con->addr[0], addr, sizeof(*addr));
+		con->addr_count = 1;
+		con->mark = dlm_config.ci_mark;
+		spin_unlock(&con->addrs_lock);
+		srcu_read_unlock(&connections_srcu, idx);
 		return 0;
 	}
 
-	ret = dlm_lowcomms_na_has_addr(na, addr);
+	ret = dlm_lowcomms_con_has_addr(con, addr);
 	if (ret) {
-		spin_unlock(&dlm_node_addrs_spin);
-		kfree(new_addr);
-		kfree(new_node);
+		spin_unlock(&con->addrs_lock);
+		srcu_read_unlock(&connections_srcu, idx);
 		return -EEXIST;
 	}
 
-	if (na->addr_count >= DLM_MAX_ADDR_COUNT) {
-		spin_unlock(&dlm_node_addrs_spin);
-		kfree(new_addr);
-		kfree(new_node);
+	if (con->addr_count >= DLM_MAX_ADDR_COUNT) {
+		spin_unlock(&con->addrs_lock);
+		srcu_read_unlock(&connections_srcu, idx);
 		return -ENOSPC;
 	}
 
-	na->addr[na->addr_count++] = new_addr;
-	spin_unlock(&dlm_node_addrs_spin);
-	kfree(new_node);
+	memcpy(&con->addr[con->addr_count++], addr, sizeof(*addr));
+	srcu_read_unlock(&connections_srcu, idx);
+	spin_unlock(&con->addrs_lock);
 	return 0;
 }
 
 /* Data available on socket or listen socket received a connect */
 static void lowcomms_data_ready(struct sock *sk)
 {
-	struct connection *con;
-
-	con = sock2con(sk);
-	if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
-		queue_work(recv_workqueue, &con->rwork);
-}
-
-static void lowcomms_listen_data_ready(struct sock *sk)
-{
-	if (!dlm_allow_conn)
-		return;
+	struct connection *con = sock2con(sk);
 
-	queue_work(recv_workqueue, &listen_con.rwork);
+	set_bit(CF_RECV_INTR, &con->flags);
+	lowcomms_queue_rwork(con);
 }
 
 static void lowcomms_write_space(struct sock *sk)
 {
-	struct connection *con;
-
-	con = sock2con(sk);
-	if (!con)
-		return;
-
-	if (!test_and_set_bit(CF_CONNECTED, &con->flags)) {
-		log_print("connected to node %d", con->nodeid);
-		queue_work(send_workqueue, &con->swork);
-		return;
-	}
+	struct connection *con = sock2con(sk);
 
 	clear_bit(SOCK_NOSPACE, &con->sock->flags);
 
+	spin_lock_bh(&con->writequeue_lock);
 	if (test_and_clear_bit(CF_APP_LIMITED, &con->flags)) {
 		con->sock->sk->sk_write_pending--;
 		clear_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags);
 	}
 
-	queue_work(send_workqueue, &con->swork);
-}
-
-static inline void lowcomms_connect_sock(struct connection *con)
-{
-	if (test_bit(CF_CLOSE, &con->flags))
-		return;
-	queue_work(send_workqueue, &con->swork);
-	cond_resched();
+	lowcomms_queue_swork(con);
+	spin_unlock_bh(&con->writequeue_lock);
 }
 
 static void lowcomms_state_change(struct sock *sk)
 {
 	/* SCTP layer is not calling sk_data_ready when the connection
-	 * is done, so we catch the signal through here. Also, it
-	 * doesn't switch socket state when entering shutdown, so we
-	 * skip the write in that case.
+	 * is done, so we catch the signal through here.
 	 */
-	if (sk->sk_shutdown) {
-		if (sk->sk_shutdown == RCV_SHUTDOWN)
-			lowcomms_data_ready(sk);
-	} else if (sk->sk_state == TCP_ESTABLISHED) {
-		lowcomms_write_space(sk);
-	}
+	if (sk->sk_shutdown == RCV_SHUTDOWN)
+		lowcomms_data_ready(sk);
+}
+
+static void lowcomms_listen_data_ready(struct sock *sk)
+{
+	queue_work(io_workqueue, &listen_con.rwork);
 }
 
 int dlm_lowcomms_connect_node(int nodeid)
@@ -576,47 +542,49 @@ int dlm_lowcomms_connect_node(int nodeid)
 		return 0;
 
 	idx = srcu_read_lock(&connections_srcu);
-	con = nodeid2con(nodeid, GFP_NOFS);
-	if (!con) {
+	con = nodeid2con(nodeid, 0);
+	if (WARN_ON_ONCE(!con)) {
 		srcu_read_unlock(&connections_srcu, idx);
-		return -ENOMEM;
+		return -ENOENT;
 	}
 
-	lowcomms_connect_sock(con);
+	down_read(&con->sock_lock);
+	if (!con->sock) {
+		spin_lock_bh(&con->writequeue_lock);
+		lowcomms_queue_swork(con);
+		spin_unlock_bh(&con->writequeue_lock);
+	}
+	up_read(&con->sock_lock);
 	srcu_read_unlock(&connections_srcu, idx);
 
+	cond_resched();
 	return 0;
 }
 
 int dlm_lowcomms_nodes_set_mark(int nodeid, unsigned int mark)
 {
-	struct dlm_node_addr *na;
+	struct connection *con;
+	int idx;
 
-	spin_lock(&dlm_node_addrs_spin);
-	na = find_node_addr(nodeid);
-	if (!na) {
-		spin_unlock(&dlm_node_addrs_spin);
+	idx = srcu_read_lock(&connections_srcu);
+	con = nodeid2con(nodeid, 0);
+	if (!con) {
+		srcu_read_unlock(&connections_srcu, idx);
 		return -ENOENT;
 	}
 
-	na->mark = mark;
-	spin_unlock(&dlm_node_addrs_spin);
-
+	spin_lock(&con->addrs_lock);
+	con->mark = mark;
+	spin_unlock(&con->addrs_lock);
+	srcu_read_unlock(&connections_srcu, idx);
 	return 0;
 }
 
 static void lowcomms_error_report(struct sock *sk)
 {
-	struct connection *con;
-	void (*orig_report)(struct sock *) = NULL;
+	struct connection *con = sock2con(sk);
 	struct inet_sock *inet;
 
-	con = sock2con(sk);
-	if (con == NULL)
-		goto out;
-
-	orig_report = listen_sock.sk_error_report;
-
 	inet = inet_sk(sk);
 	switch (sk->sk_family) {
 	case AF_INET:
@@ -642,66 +610,25 @@ static void lowcomms_error_report(struct sock *sk)
 				   "invalid socket family %d set, "
 				   "sk_err=%d/%d\n", dlm_our_nodeid(),
 				   sk->sk_family, sk->sk_err, sk->sk_err_soft);
-		goto out;
-	}
-
-	/* below sendcon only handling */
-	if (test_bit(CF_IS_OTHERCON, &con->flags))
-		con = con->sendcon;
-
-	switch (sk->sk_err) {
-	case ECONNREFUSED:
-		set_bit(CF_DELAY_CONNECT, &con->flags);
-		break;
-	default:
 		break;
 	}
 
-	if (!test_and_set_bit(CF_RECONNECT, &con->flags))
-		queue_work(send_workqueue, &con->swork);
+	dlm_midcomms_unack_msg_resend(con->nodeid);
 
-out:
-	if (orig_report)
-		orig_report(sk);
+	listen_sock.sk_error_report(sk);
 }
 
-/* Note: sk_callback_lock must be locked before calling this function. */
-static void save_listen_callbacks(struct socket *sock)
+static void restore_callbacks(struct sock *sk)
 {
-	struct sock *sk = sock->sk;
-
-	listen_sock.sk_data_ready = sk->sk_data_ready;
-	listen_sock.sk_state_change = sk->sk_state_change;
-	listen_sock.sk_write_space = sk->sk_write_space;
-	listen_sock.sk_error_report = sk->sk_error_report;
-}
-
-static void restore_callbacks(struct socket *sock)
-{
-	struct sock *sk = sock->sk;
+#ifdef CONFIG_LOCKDEP
+	WARN_ON_ONCE(!lockdep_sock_is_held(sk));
+#endif
 
-	lock_sock(sk);
 	sk->sk_user_data = NULL;
 	sk->sk_data_ready = listen_sock.sk_data_ready;
 	sk->sk_state_change = listen_sock.sk_state_change;
 	sk->sk_write_space = listen_sock.sk_write_space;
 	sk->sk_error_report = listen_sock.sk_error_report;
-	release_sock(sk);
-}
-
-static void add_listen_sock(struct socket *sock, struct listen_connection *con)
-{
-	struct sock *sk = sock->sk;
-
-	lock_sock(sk);
-	save_listen_callbacks(sock);
-	con->sock = sock;
-
-	sk->sk_user_data = con;
-	sk->sk_allocation = GFP_NOFS;
-	/* Install a data_ready callback */
-	sk->sk_data_ready = lowcomms_listen_data_ready;
-	release_sock(sk);
 }
 
 /* Make a socket active */
@@ -713,10 +640,10 @@ static void add_sock(struct socket *sock, struct connection *con)
 	con->sock = sock;
 
 	sk->sk_user_data = con;
-	/* Install a data_ready callback */
 	sk->sk_data_ready = lowcomms_data_ready;
 	sk->sk_write_space = lowcomms_write_space;
-	sk->sk_state_change = lowcomms_state_change;
+	if (dlm_config.ci_protocol == DLM_PROTO_SCTP)
+		sk->sk_state_change = lowcomms_state_change;
 	sk->sk_allocation = GFP_NOFS;
 	sk->sk_error_report = lowcomms_error_report;
 	release_sock(sk);
@@ -727,7 +654,7 @@ static void add_sock(struct socket *sock, struct connection *con)
 static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
 			  int *addr_len)
 {
-	saddr->ss_family =  dlm_local_addr[0]->ss_family;
+	saddr->ss_family =  dlm_local_addr[0].ss_family;
 	if (saddr->ss_family == AF_INET) {
 		struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
 		in4_addr->sin_port = cpu_to_be16(port);
@@ -773,43 +700,67 @@ static void free_entry(struct writequeue_entry *e)
 	}
 
 	list_del(&e->list);
-	atomic_dec(&e->con->writequeue_cnt);
 	kref_put(&e->ref, dlm_page_release);
 }
 
 static void dlm_close_sock(struct socket **sock)
 {
-	if (*sock) {
-		restore_callbacks(*sock);
-		sock_release(*sock);
-		*sock = NULL;
+	lock_sock((*sock)->sk);
+	restore_callbacks((*sock)->sk);
+	release_sock((*sock)->sk);
+
+	sock_release(*sock);
+	*sock = NULL;
+}
+
+static void allow_connection_io(struct connection *con)
+{
+	if (con->othercon)
+		clear_bit(CF_IO_STOP, &con->othercon->flags);
+	clear_bit(CF_IO_STOP, &con->flags);
+}
+
+static void stop_connection_io(struct connection *con)
+{
+	if (con->othercon)
+		stop_connection_io(con->othercon);
+
+	down_write(&con->sock_lock);
+	if (con->sock) {
+		lock_sock(con->sock->sk);
+		restore_callbacks(con->sock->sk);
+
+		spin_lock_bh(&con->writequeue_lock);
+		set_bit(CF_IO_STOP, &con->flags);
+		spin_unlock_bh(&con->writequeue_lock);
+		release_sock(con->sock->sk);
+	} else {
+		spin_lock_bh(&con->writequeue_lock);
+		set_bit(CF_IO_STOP, &con->flags);
+		spin_unlock_bh(&con->writequeue_lock);
 	}
+	up_write(&con->sock_lock);
+
+	cancel_work_sync(&con->swork);
+	cancel_work_sync(&con->rwork);
 }
 
 /* Close a remote connection and tidy up */
-static void close_connection(struct connection *con, bool and_other,
-			     bool tx, bool rx)
+static void close_connection(struct connection *con, bool and_other)
 {
-	bool closing = test_and_set_bit(CF_CLOSING, &con->flags);
 	struct writequeue_entry *e;
 
-	if (tx && !closing && cancel_work_sync(&con->swork)) {
-		log_print("canceled swork for node %d", con->nodeid);
-		clear_bit(CF_WRITE_PENDING, &con->flags);
-	}
-	if (rx && !closing && cancel_work_sync(&con->rwork)) {
-		log_print("canceled rwork for node %d", con->nodeid);
-		clear_bit(CF_READ_PENDING, &con->flags);
+	if (con->othercon && and_other)
+		close_connection(con->othercon, false);
+
+	down_write(&con->sock_lock);
+	if (!con->sock) {
+		up_write(&con->sock_lock);
+		return;
 	}
 
-	mutex_lock(&con->sock_mutex);
 	dlm_close_sock(&con->sock);
 
-	if (con->othercon && and_other) {
-		/* Will only re-enter once. */
-		close_connection(con->othercon, false, tx, rx);
-	}
-
 	/* if we send a writequeue entry only a half way, we drop the
 	 * whole entry because reconnection and that we not start of the
 	 * middle of a msg which will confuse the other end.
@@ -821,200 +772,209 @@ static void close_connection(struct connection *con, bool and_other,
 	 * our policy is to start on a clean state when disconnects, we don't
 	 * know what's send/received on transport layer in this case.
 	 */
-	spin_lock(&con->writequeue_lock);
+	spin_lock_bh(&con->writequeue_lock);
 	if (!list_empty(&con->writequeue)) {
 		e = list_first_entry(&con->writequeue, struct writequeue_entry,
 				     list);
 		if (e->dirty)
 			free_entry(e);
 	}
-	spin_unlock(&con->writequeue_lock);
+	spin_unlock_bh(&con->writequeue_lock);
 
 	con->rx_leftover = 0;
 	con->retries = 0;
 	clear_bit(CF_APP_LIMITED, &con->flags);
-	clear_bit(CF_CONNECTED, &con->flags);
-	clear_bit(CF_DELAY_CONNECT, &con->flags);
-	clear_bit(CF_RECONNECT, &con->flags);
-	clear_bit(CF_EOF, &con->flags);
-	mutex_unlock(&con->sock_mutex);
-	clear_bit(CF_CLOSING, &con->flags);
+	clear_bit(CF_RECV_PENDING, &con->flags);
+	clear_bit(CF_SEND_PENDING, &con->flags);
+	up_write(&con->sock_lock);
 }
 
-static void shutdown_connection(struct connection *con)
+static struct processqueue_entry *new_processqueue_entry(int nodeid,
+							 int buflen)
 {
-	int ret;
-
-	flush_work(&con->swork);
+	struct processqueue_entry *pentry;
 
-	mutex_lock(&con->sock_mutex);
-	/* nothing to shutdown */
-	if (!con->sock) {
-		mutex_unlock(&con->sock_mutex);
-		return;
-	}
+	pentry = kmalloc(sizeof(*pentry), GFP_NOFS);
+	if (!pentry)
+		return NULL;
 
-	set_bit(CF_SHUTDOWN, &con->flags);
-	ret = kernel_sock_shutdown(con->sock, SHUT_WR);
-	mutex_unlock(&con->sock_mutex);
-	if (ret) {
-		log_print("Connection %p failed to shutdown: %d will force close",
-			  con, ret);
-		goto force_close;
-	} else {
-		ret = wait_event_timeout(con->shutdown_wait,
-					 !test_bit(CF_SHUTDOWN, &con->flags),
-					 DLM_SHUTDOWN_WAIT_TIMEOUT);
-		if (ret == 0) {
-			log_print("Connection %p shutdown timed out, will force close",
-				  con);
-			goto force_close;
-		}
+	pentry->buf = kmalloc(buflen, GFP_NOFS);
+	if (!pentry->buf) {
+		kfree(pentry);
+		return NULL;
 	}
 
-	return;
+	pentry->nodeid = nodeid;
+	return pentry;
+}
 
-force_close:
-	clear_bit(CF_SHUTDOWN, &con->flags);
-	close_connection(con, false, true, true);
+static void free_processqueue_entry(struct processqueue_entry *pentry)
+{
+	kfree(pentry->buf);
+	kfree(pentry);
 }
 
-static void dlm_tcp_shutdown(struct connection *con)
+struct dlm_processed_nodes {
+	int nodeid;
+
+	struct list_head list;
+};
+
+static void add_processed_node(int nodeid, struct list_head *processed_nodes)
 {
-	if (con->othercon)
-		shutdown_connection(con->othercon);
-	shutdown_connection(con);
+	struct dlm_processed_nodes *n;
+
+	list_for_each_entry(n, processed_nodes, list) {
+		/* we already remembered this node */
+		if (n->nodeid == nodeid)
+			return;
+	}
+
+	/* if it's fails in worst case we simple don't send an ack back.
+	 * We try it next time.
+	 */
+	n = kmalloc(sizeof(*n), GFP_NOFS);
+	if (!n)
+		return;
+
+	n->nodeid = nodeid;
+	list_add(&n->list, processed_nodes);
 }
 
-static int con_realloc_receive_buf(struct connection *con, int newlen)
+static void process_dlm_messages(struct work_struct *work)
 {
-	unsigned char *newbuf;
+	struct dlm_processed_nodes *n, *n_tmp;
+	struct processqueue_entry *pentry;
+	LIST_HEAD(processed_nodes);
 
-	newbuf = kmalloc(newlen, GFP_NOFS);
-	if (!newbuf)
-		return -ENOMEM;
+	spin_lock(&processqueue_lock);
+	pentry = list_first_entry_or_null(&processqueue,
+					  struct processqueue_entry, list);
+	if (WARN_ON_ONCE(!pentry)) {
+		spin_unlock(&processqueue_lock);
+		return;
+	}
 
-	/* copy any leftover from last receive */
-	if (con->rx_leftover)
-		memmove(newbuf, con->rx_buf, con->rx_leftover);
+	list_del(&pentry->list);
+	spin_unlock(&processqueue_lock);
 
-	/* swap to new buffer space */
-	kfree(con->rx_buf);
-	con->rx_buflen = newlen;
-	con->rx_buf = newbuf;
+	for (;;) {
+		dlm_process_incoming_buffer(pentry->nodeid, pentry->buf,
+					    pentry->buflen);
+		add_processed_node(pentry->nodeid, &processed_nodes);
+		free_processqueue_entry(pentry);
+
+		spin_lock(&processqueue_lock);
+		pentry = list_first_entry_or_null(&processqueue,
+						  struct processqueue_entry, list);
+		if (!pentry) {
+			process_dlm_messages_pending = false;
+			spin_unlock(&processqueue_lock);
+			break;
+		}
 
-	return 0;
+		list_del(&pentry->list);
+		spin_unlock(&processqueue_lock);
+	}
+
+	/* send ack back after we processed couple of messages */
+	list_for_each_entry_safe(n, n_tmp, &processed_nodes, list) {
+		list_del(&n->list);
+		dlm_midcomms_receive_done(n->nodeid);
+		kfree(n);
+	}
 }
 
 /* Data received from remote end */
-static int receive_from_sock(struct connection *con)
+static int receive_from_sock(struct connection *con, int buflen)
 {
+	struct processqueue_entry *pentry;
+	int ret, buflen_real;
 	struct msghdr msg;
 	struct kvec iov;
-	int ret, buflen;
 
-	mutex_lock(&con->sock_mutex);
+	pentry = new_processqueue_entry(con->nodeid, buflen);
+	if (!pentry)
+		return DLM_IO_RESCHED;
 
-	if (con->sock == NULL) {
-		ret = -EAGAIN;
-		goto out_close;
-	}
-
-	/* realloc if we get new buffer size to read out */
-	buflen = dlm_config.ci_buffer_size;
-	if (con->rx_buflen != buflen && con->rx_leftover <= buflen) {
-		ret = con_realloc_receive_buf(con, buflen);
-		if (ret < 0)
-			goto out_resched;
-	}
+	memcpy(pentry->buf, con->rx_leftover_buf, con->rx_leftover);
 
-	for (;;) {
-		/* calculate new buffer parameter regarding last receive and
-		 * possible leftover bytes
-		 */
-		iov.iov_base = con->rx_buf + con->rx_leftover;
-		iov.iov_len = con->rx_buflen - con->rx_leftover;
-
-		memset(&msg, 0, sizeof(msg));
-		msg.msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
-		ret = kernel_recvmsg(con->sock, &msg, &iov, 1, iov.iov_len,
-				     msg.msg_flags);
-		trace_dlm_recv(con->nodeid, ret);
-		if (ret == -EAGAIN)
-			break;
-		else if (ret <= 0)
-			goto out_close;
-
-		/* new buflen according readed bytes and leftover from last receive */
-		buflen = ret + con->rx_leftover;
-		ret = dlm_process_incoming_buffer(con->nodeid, con->rx_buf, buflen);
-		if (ret < 0)
-			goto out_close;
-
-		/* calculate leftover bytes from process and put it into begin of
-		 * the receive buffer, so next receive we have the full message
-		 * at the start address of the receive buffer.
-		 */
-		con->rx_leftover = buflen - ret;
-		if (con->rx_leftover) {
-			memmove(con->rx_buf, con->rx_buf + ret,
-				con->rx_leftover);
+	/* calculate new buffer parameter regarding last receive and
+	 * possible leftover bytes
+	 */
+	iov.iov_base = pentry->buf + con->rx_leftover;
+	iov.iov_len = buflen - con->rx_leftover;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
+	clear_bit(CF_RECV_INTR, &con->flags);
+again:
+	ret = kernel_recvmsg(con->sock, &msg, &iov, 1, iov.iov_len,
+			     msg.msg_flags);
+	trace_dlm_recv(con->nodeid, ret);
+	if (ret == -EAGAIN) {
+		lock_sock(con->sock->sk);
+		if (test_and_clear_bit(CF_RECV_INTR, &con->flags)) {
+			release_sock(con->sock->sk);
+			goto again;
 		}
+
+		clear_bit(CF_RECV_PENDING, &con->flags);
+		release_sock(con->sock->sk);
+		free_processqueue_entry(pentry);
+		return DLM_IO_END;
+	} else if (ret == 0) {
+		/* close will clear CF_RECV_PENDING */
+		free_processqueue_entry(pentry);
+		return DLM_IO_EOF;
+	} else if (ret < 0) {
+		free_processqueue_entry(pentry);
+		return ret;
 	}
 
-	dlm_midcomms_receive_done(con->nodeid);
-	mutex_unlock(&con->sock_mutex);
-	return 0;
+	/* new buflen according readed bytes and leftover from last receive */
+	buflen_real = ret + con->rx_leftover;
+	ret = dlm_validate_incoming_buffer(con->nodeid, pentry->buf,
+					   buflen_real);
+	if (ret < 0) {
+		free_processqueue_entry(pentry);
+		return ret;
+	}
 
-out_resched:
-	if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
-		queue_work(recv_workqueue, &con->rwork);
-	mutex_unlock(&con->sock_mutex);
-	return -EAGAIN;
-
-out_close:
-	if (ret == 0) {
-		log_print("connection %p got EOF from %d",
-			  con, con->nodeid);
-
-		if (dlm_proto_ops->eof_condition &&
-		    dlm_proto_ops->eof_condition(con)) {
-			set_bit(CF_EOF, &con->flags);
-			mutex_unlock(&con->sock_mutex);
-		} else {
-			mutex_unlock(&con->sock_mutex);
-			close_connection(con, false, true, false);
+	pentry->buflen = ret;
 
-			/* handling for tcp shutdown */
-			clear_bit(CF_SHUTDOWN, &con->flags);
-			wake_up(&con->shutdown_wait);
-		}
+	/* calculate leftover bytes from process and put it into begin of
+	 * the receive buffer, so next receive we have the full message
+	 * at the start address of the receive buffer.
+	 */
+	con->rx_leftover = buflen_real - ret;
+	memmove(con->rx_leftover_buf, pentry->buf + ret,
+		con->rx_leftover);
 
-		/* signal to breaking receive worker */
-		ret = -1;
-	} else {