dlm for 4.15

This set focuses, as usual, on fixes to the comms layer.
 New testing of the dlm with ocfs2 uncovered a number of
 bugs in the TCP connection handling during recovery,
 starting, and stopping.
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Merge tag 'dlm-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm

Pull dlm updates from David Teigland:
 "This set focuses, as usual, on fixes to the comms layer.

  New testing of the dlm with ocfs2 uncovered a number of bugs in the
  TCP connection handling during recovery, starting, and stopping"

* tag 'dlm-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm:
  dlm: remove dlm_send_rcom_lookup_dump
  dlm: recheck kthread_should_stop() before schedule()
  DLM: fix NULL pointer dereference in send_to_sock()
  DLM: fix to reschedule rwork
  DLM: fix to use sk_callback_lock correctly
  DLM: fix overflow dlm_cb_seq
  DLM: fix memory leak in tcp_accept_from_sock()
  DLM: fix conversion deadlock when DLM_LKF_NODLCKWT flag is set
  DLM: use CF_CLOSE flag to stop dlm_send correctly
  DLM: Reanimate CF_WRITE_PENDING flag
  DLM: fix race condition between dlm_recoverd_stop and dlm_recoverd
  DLM: close othercon at send/receive error
  DLM: retry rcom when dlm_wait_function is timed out.
  DLM: fix to use sock_mutex correctly in xxx_accept_from_sock
  DLM: fix race condition between dlm_send and dlm_recv
  DLM: fix double list_del()
  DLM: fix remove save_cb argument from add_sock()
  DLM: Fix saving of NULL callbacks
  DLM: Eliminate CF_WRITE_PENDING flag
  DLM: Eliminate CF_CONNECT_PENDING flag

fs/dlm/ast.c

@@ -181,6 +181,8 @@ void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
 
 	spin_lock(&dlm_cb_seq_spin);
 	new_seq = ++dlm_cb_seq;
+	if (!dlm_cb_seq)
+		new_seq = ++dlm_cb_seq;
 	spin_unlock(&dlm_cb_seq_spin);
 
 	if (lkb->lkb_flags & DLM_IFL_USER) {

fs/dlm/lock.c

@@ -1003,7 +1003,6 @@ int dlm_master_lookup(struct dlm_ls *ls, int from_nodeid, char *name, int len,
 		if (r->res_master_nodeid == our_nodeid) {
 			log_error(ls, "from_master %d our_master", from_nodeid);
 			dlm_dump_rsb(r);
-			dlm_send_rcom_lookup_dump(r, from_nodeid);
 			goto out_found;
 		}
 
@@ -2465,14 +2464,12 @@ static int can_be_granted(struct dlm_rsb *r, struct dlm_lkb *lkb, int now,
 		if (lkb->lkb_exflags & DLM_LKF_CONVDEADLK) {
 			lkb->lkb_grmode = DLM_LOCK_NL;
 			lkb->lkb_sbflags |= DLM_SBF_DEMOTED;
-		} else if (!(lkb->lkb_exflags & DLM_LKF_NODLCKWT)) {
+		} else if (err) {
-			if (err)
+			*err = -EDEADLK;
-				*err = -EDEADLK;
+		} else {
-			else {
+			log_print("can_be_granted deadlock %x now %d",
-				log_print("can_be_granted deadlock %x now %d",
+				  lkb->lkb_id, now);
-					  lkb->lkb_id, now);
+			dlm_dump_rsb(r);
-				dlm_dump_rsb(r);
-			}
 		}
 		goto out;
 	}
@@ -2501,13 +2498,6 @@ static int can_be_granted(struct dlm_rsb *r, struct dlm_lkb *lkb, int now,
 	return rv;
 }
 
-/* FIXME: I don't think that can_be_granted() can/will demote or find deadlock
-   for locks pending on the convert list.  Once verified (watch for these
-   log_prints), we should be able to just call _can_be_granted() and not
-   bother with the demote/deadlk cases here (and there's no easy way to deal
-   with a deadlk here, we'd have to generate something like grant_lock with
-   the deadlk error.) */
-
 /* Returns the highest requested mode of all blocked conversions; sets
    cw if there's a blocked conversion to DLM_LOCK_CW. */
 
@@ -2545,9 +2535,22 @@ static int grant_pending_convert(struct dlm_rsb *r, int high, int *cw,
 		}
 
 		if (deadlk) {
-			log_print("WARN: pending deadlock %x node %d %s",
+			/*
-				  lkb->lkb_id, lkb->lkb_nodeid, r->res_name);
+			 * If DLM_LKB_NODLKWT flag is set and conversion
-			dlm_dump_rsb(r);
+			 * deadlock is detected, we request blocking AST and
+			 * down (or cancel) conversion.
+			 */
+			if (lkb->lkb_exflags & DLM_LKF_NODLCKWT) {
+				if (lkb->lkb_highbast < lkb->lkb_rqmode) {
+					queue_bast(r, lkb, lkb->lkb_rqmode);
+					lkb->lkb_highbast = lkb->lkb_rqmode;
+				}
+			} else {
+				log_print("WARN: pending deadlock %x node %d %s",
+					  lkb->lkb_id, lkb->lkb_nodeid,
+					  r->res_name);
+				dlm_dump_rsb(r);
+			}
 			continue;
 		}
 
@@ -3123,7 +3126,7 @@ static int do_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
 	   deadlock, so we leave it on the granted queue and return EDEADLK in
 	   the ast for the convert. */
 
-	if (deadlk) {
+	if (deadlk && !(lkb->lkb_exflags & DLM_LKF_NODLCKWT)) {
 		/* it's left on the granted queue */
 		revert_lock(r, lkb);
 		queue_cast(r, lkb, -EDEADLK);

fs/dlm/lowcomms.c

@@ -107,11 +107,11 @@ struct connection {
 	unsigned long flags;
 #define CF_READ_PENDING 1
 #define CF_WRITE_PENDING 2
-#define CF_CONNECT_PENDING 3
 #define CF_INIT_PENDING 4
 #define CF_IS_OTHERCON 5
 #define CF_CLOSE 6
 #define CF_APP_LIMITED 7
+#define CF_CLOSING 8
 	struct list_head writequeue;  /* List of outgoing writequeue_entries */
 	spinlock_t writequeue_lock;
 	int (*rx_action) (struct connection *);	/* What to do when active */
@@ -124,10 +124,6 @@ struct connection {
 	struct connection *othercon;
 	struct work_struct rwork; /* Receive workqueue */
 	struct work_struct swork; /* Send workqueue */
-	void (*orig_error_report)(struct sock *);
-	void (*orig_data_ready)(struct sock *);
-	void (*orig_state_change)(struct sock *);
-	void (*orig_write_space)(struct sock *);
 };
 #define sock2con(x) ((struct connection *)(x)->sk_user_data)
 
@@ -150,6 +146,13 @@ struct dlm_node_addr {
 	struct sockaddr_storage *addr[DLM_MAX_ADDR_COUNT];
 };
 
+static struct listen_sock_callbacks {
+	void (*sk_error_report)(struct sock *);
+	void (*sk_data_ready)(struct sock *);
+	void (*sk_state_change)(struct sock *);
+	void (*sk_write_space)(struct sock *);
+} listen_sock;
+
 static LIST_HEAD(dlm_node_addrs);
 static DEFINE_SPINLOCK(dlm_node_addrs_spin);
 
@@ -408,17 +411,23 @@ int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr, int len)
 /* Data available on socket or listen socket received a connect */
 static void lowcomms_data_ready(struct sock *sk)
 {
-	struct connection *con = sock2con(sk);
+	struct connection *con;
+
+	read_lock_bh(&sk->sk_callback_lock);
+	con = sock2con(sk);
 	if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
 		queue_work(recv_workqueue, &con->rwork);
+	read_unlock_bh(&sk->sk_callback_lock);
 }
 
 static void lowcomms_write_space(struct sock *sk)
 {
-	struct connection *con = sock2con(sk);
+	struct connection *con;
 
+	read_lock_bh(&sk->sk_callback_lock);
+	con = sock2con(sk);
 	if (!con)
-		return;
+		goto out;
 
 	clear_bit(SOCK_NOSPACE, &con->sock->flags);
 
@@ -427,16 +436,17 @@ static void lowcomms_write_space(struct sock *sk)
 		clear_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags);
 	}
 
-	if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
+	queue_work(send_workqueue, &con->swork);
-		queue_work(send_workqueue, &con->swork);
+out:
+	read_unlock_bh(&sk->sk_callback_lock);
 }
 
 static inline void lowcomms_connect_sock(struct connection *con)
 {
 	if (test_bit(CF_CLOSE, &con->flags))
 		return;
-	if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
+	queue_work(send_workqueue, &con->swork);
-		queue_work(send_workqueue, &con->swork);
+	cond_resched();
 }
 
 static void lowcomms_state_change(struct sock *sk)
@@ -480,7 +490,7 @@ static void lowcomms_error_report(struct sock *sk)
 	if (con == NULL)
 		goto out;
 
-	orig_report = con->orig_error_report;
+	orig_report = listen_sock.sk_error_report;
 	if (con->sock == NULL ||
 	    kernel_getpeername(con->sock, (struct sockaddr *)&saddr, &buflen)) {
 		printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
@@ -517,27 +527,31 @@ out:
 }
 
 /* Note: sk_callback_lock must be locked before calling this function. */
-static void save_callbacks(struct connection *con, struct sock *sk)
+static void save_listen_callbacks(struct socket *sock)
 {
-	con->orig_data_ready = sk->sk_data_ready;
+	struct sock *sk = sock->sk;
-	con->orig_state_change = sk->sk_state_change;
+
-	con->orig_write_space = sk->sk_write_space;
+	listen_sock.sk_data_ready = sk->sk_data_ready;
-	con->orig_error_report = sk->sk_error_report;
+	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 connection *con, struct sock *sk)
+static void restore_callbacks(struct socket *sock)
 {
+	struct sock *sk = sock->sk;
+
 	write_lock_bh(&sk->sk_callback_lock);
 	sk->sk_user_data = NULL;
-	sk->sk_data_ready = con->orig_data_ready;
+	sk->sk_data_ready = listen_sock.sk_data_ready;
-	sk->sk_state_change = con->orig_state_change;
+	sk->sk_state_change = listen_sock.sk_state_change;
-	sk->sk_write_space = con->orig_write_space;
+	sk->sk_write_space = listen_sock.sk_write_space;
-	sk->sk_error_report = con->orig_error_report;
+	sk->sk_error_report = listen_sock.sk_error_report;
 	write_unlock_bh(&sk->sk_callback_lock);
 }
 
 /* Make a socket active */
-static void add_sock(struct socket *sock, struct connection *con, bool save_cb)
+static void add_sock(struct socket *sock, struct connection *con)
 {
 	struct sock *sk = sock->sk;
 
@@ -545,8 +559,6 @@ static void add_sock(struct socket *sock, struct connection *con, bool save_cb)
 	con->sock = sock;
 
 	sk->sk_user_data = con;
-	if (save_cb)
-		save_callbacks(con, sk);
 	/* Install a data_ready callback */
 	sk->sk_data_ready = lowcomms_data_ready;
 	sk->sk_write_space = lowcomms_write_space;
@@ -579,17 +591,20 @@ static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
 static void close_connection(struct connection *con, bool and_other,
 			     bool tx, bool rx)
 {
-	clear_bit(CF_CONNECT_PENDING, &con->flags);
+	bool closing = test_and_set_bit(CF_CLOSING, &con->flags);
-	clear_bit(CF_WRITE_PENDING, &con->flags);
+
-	if (tx && cancel_work_sync(&con->swork))
+	if (tx && !closing && cancel_work_sync(&con->swork)) {
 		log_print("canceled swork for node %d", con->nodeid);
-	if (rx && cancel_work_sync(&con->rwork))
+		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);
+	}
 
 	mutex_lock(&con->sock_mutex);
 	if (con->sock) {
-		if (!test_bit(CF_IS_OTHERCON, &con->flags))
+		restore_callbacks(con->sock);
-			restore_callbacks(con, con->sock->sk);
 		sock_release(con->sock);
 		con->sock = NULL;
 	}
@@ -604,6 +619,7 @@ static void close_connection(struct connection *con, bool and_other,
 
 	con->retries = 0;
 	mutex_unlock(&con->sock_mutex);
+	clear_bit(CF_CLOSING, &con->flags);
 }
 
 /* Data received from remote end */
@@ -700,7 +716,7 @@ out_resched:
 out_close:
 	mutex_unlock(&con->sock_mutex);
 	if (ret != -EAGAIN) {
-		close_connection(con, false, true, false);
+		close_connection(con, true, true, false);
 		/* Reconnect when there is something to send */
 	}
 	/* Don't return success if we really got EOF */
@@ -728,22 +744,14 @@ static int tcp_accept_from_sock(struct connection *con)
 	}
 	mutex_unlock(&connections_lock);
 
-	memset(&peeraddr, 0, sizeof(peeraddr));
-	result = sock_create_lite(dlm_local_addr[0]->ss_family,
-				  SOCK_STREAM, IPPROTO_TCP, &newsock);
-	if (result < 0)
-		return -ENOMEM;
-
 	mutex_lock_nested(&con->sock_mutex, 0);
 
-	result = -ENOTCONN;
+	if (!con->sock) {
-	if (con->sock == NULL)
+		mutex_unlock(&con->sock_mutex);
-		goto accept_err;
+		return -ENOTCONN;
+	}
 
-	newsock->type = con->sock->type;
+	result = kernel_accept(con->sock, &newsock, O_NONBLOCK);
-	newsock->ops = con->sock->ops;
-
-	result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK, true);
 	if (result < 0)
 		goto accept_err;
 
@@ -794,31 +802,33 @@ static int tcp_accept_from_sock(struct connection *con)
 			othercon->nodeid = nodeid;
 			othercon->rx_action = receive_from_sock;
 			mutex_init(&othercon->sock_mutex);
+			INIT_LIST_HEAD(&othercon->writequeue);
+			spin_lock_init(&othercon->writequeue_lock);
 			INIT_WORK(&othercon->swork, process_send_sockets);
 			INIT_WORK(&othercon->rwork, process_recv_sockets);
 			set_bit(CF_IS_OTHERCON, &othercon->flags);
 		}
+		mutex_lock_nested(&othercon->sock_mutex, 2);
 		if (!othercon->sock) {
 			newcon->othercon = othercon;
-			othercon->sock = newsock;
+			add_sock(newsock, othercon);
-			newsock->sk->sk_user_data = othercon;
-			add_sock(newsock, othercon, false);
 			addcon = othercon;
+			mutex_unlock(&othercon->sock_mutex);
 		}
 		else {
 			printk("Extra connection from node %d attempted\n", nodeid);
 			result = -EAGAIN;
+			mutex_unlock(&othercon->sock_mutex);
 			mutex_unlock(&newcon->sock_mutex);
 			goto accept_err;
 		}
 	}
 	else {
-		newsock->sk->sk_user_data = newcon;
 		newcon->rx_action = receive_from_sock;
 		/* accept copies the sk after we've saved the callbacks, so we
 		   don't want to save them a second time or comm errors will
 		   result in calling sk_error_report recursively. */
-		add_sock(newsock, newcon, false);
+		add_sock(newsock, newcon);
 		addcon = newcon;
 	}
 
@@ -837,7 +847,8 @@ static int tcp_accept_from_sock(struct connection *con)
 
 accept_err:
 	mutex_unlock(&con->sock_mutex);
-	sock_release(newsock);
+	if (newsock)
+		sock_release(newsock);
 
 	if (result != -EAGAIN)
 		log_print("error accepting connection from node: %d", result);
@@ -911,26 +922,28 @@ static int sctp_accept_from_sock(struct connection *con)
 			othercon->nodeid = nodeid;
 			othercon->rx_action = receive_from_sock;
 			mutex_init(&othercon->sock_mutex);
+			INIT_LIST_HEAD(&othercon->writequeue);
+			spin_lock_init(&othercon->writequeue_lock);
 			INIT_WORK(&othercon->swork, process_send_sockets);
 			INIT_WORK(&othercon->rwork, process_recv_sockets);
 			set_bit(CF_IS_OTHERCON, &othercon->flags);
 		}
+		mutex_lock_nested(&othercon->sock_mutex, 2);
 		if (!othercon->sock) {
 			newcon->othercon = othercon;
-			othercon->sock = newsock;
+			add_sock(newsock, othercon);
-			newsock->sk->sk_user_data = othercon;
-			add_sock(newsock, othercon, false);
 			addcon = othercon;
+			mutex_unlock(&othercon->sock_mutex);
 		} else {
 			printk("Extra connection from node %d attempted\n", nodeid);
 			ret = -EAGAIN;
+			mutex_unlock(&othercon->sock_mutex);
 			mutex_unlock(&newcon->sock_mutex);
 			goto accept_err;
 		}
 	} else {
-		newsock->sk->sk_user_data = newcon;
 		newcon->rx_action = receive_from_sock;
-		add_sock(newsock, newcon, false);
+		add_sock(newsock, newcon);
 		addcon = newcon;
 	}
 
@@ -1055,10 +1068,9 @@ static void sctp_connect_to_sock(struct connection *con)
 	if (result < 0)
 		goto socket_err;
 
-	sock->sk->sk_user_data = con;
 	con->rx_action = receive_from_sock;
 	con->connect_action = sctp_connect_to_sock;
-	add_sock(sock, con, true);
+	add_sock(sock, con);
 
 	/* Bind to all addresses. */
 	if (sctp_bind_addrs(con, 0))
@@ -1079,7 +1091,6 @@ static void sctp_connect_to_sock(struct connection *con)
 	if (result == 0)
 		goto out;
 
-
 bind_err:
 	con->sock = NULL;
 	sock_release(sock);
@@ -1098,14 +1109,12 @@ socket_err:
 			  con->retries, result);
 		mutex_unlock(&con->sock_mutex);
 		msleep(1000);
-		clear_bit(CF_CONNECT_PENDING, &con->flags);
 		lowcomms_connect_sock(con);
 		return;
 	}
 
 out:
 	mutex_unlock(&con->sock_mutex);
-	set_bit(CF_WRITE_PENDING, &con->flags);
 }
 
 /* Connect a new socket to its peer */
@@ -1143,10 +1152,9 @@ static void tcp_connect_to_sock(struct connection *con)
 		goto out_err;
 	}
 
-	sock->sk->sk_user_data = con;
 	con->rx_action = receive_from_sock;
 	con->connect_action = tcp_connect_to_sock;
-	add_sock(sock, con, true);
+	add_sock(sock, con);
 
 	/* Bind to our cluster-known address connecting to avoid
 	   routing problems */
@@ -1194,13 +1202,11 @@ out_err:
 			  con->retries, result);
 		mutex_unlock(&con->sock_mutex);
 		msleep(1000);
-		clear_bit(CF_CONNECT_PENDING, &con->flags);
 		lowcomms_connect_sock(con);
 		return;
 	}
 out:
 	mutex_unlock(&con->sock_mutex);
-	set_bit(CF_WRITE_PENDING, &con->flags);
 	return;
 }
 
@@ -1235,10 +1241,12 @@ static struct socket *tcp_create_listen_sock(struct connection *con,
 	if (result < 0) {
 		log_print("Failed to set SO_REUSEADDR on socket: %d", result);
 	}
+	write_lock_bh(&sock->sk->sk_callback_lock);
 	sock->sk->sk_user_data = con;
-
+	save_listen_callbacks(sock);
 	con->rx_action = tcp_accept_from_sock;
 	con->connect_action = tcp_connect_to_sock;
+	write_unlock_bh(&sock->sk->sk_callback_lock);
 
 	/* Bind to our port */
 	make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
@@ -1320,6 +1328,7 @@ static int sctp_listen_for_all(void)
 	write_lock_bh(&sock->sk->sk_callback_lock);
 	/* Init con struct */
 	sock->sk->sk_user_data = con;
+	save_listen_callbacks(sock);
 	con->sock = sock;
 	con->sock->sk->sk_data_ready = lowcomms_data_ready;
 	con->rx_action = sctp_accept_from_sock;
@@ -1366,7 +1375,7 @@ static int tcp_listen_for_all(void)
 
 	sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
 	if (sock) {
-		add_sock(sock, con, true);
+		add_sock(sock, con);
 		result = 0;
 	}
 	else {
@@ -1456,9 +1465,7 @@ void dlm_lowcomms_commit_buffer(void *mh)
 	e->len = e->end - e->offset;
 	spin_unlock(&con->writequeue_lock);
 
-	if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
+	queue_work(send_workqueue, &con->swork);
-		queue_work(send_workqueue, &con->swork);
-	}
 	return;
 
 out:
@@ -1527,13 +1534,16 @@ out:
 
 send_error:
 	mutex_unlock(&con->sock_mutex);
-	close_connection(con, false, false, true);
+	close_connection(con, true, false, true);
-	lowcomms_connect_sock(con);
+	/* Requeue the send work. When the work daemon runs again, it will try
+	   a new connection, then call this function again. */
+	queue_work(send_workqueue, &con->swork);
 	return;
 
 out_connect:
 	mutex_unlock(&con->sock_mutex);
-	lowcomms_connect_sock(con);
+	queue_work(send_workqueue, &con->swork);
+	cond_resched();
 }
 
 static void clean_one_writequeue(struct connection *con)
@@ -1593,9 +1603,10 @@ static void process_send_sockets(struct work_struct *work)
 {
 	struct connection *con = container_of(work, struct connection, swork);
 
-	if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags))
+	clear_bit(CF_WRITE_PENDING, &con->flags);
+	if (con->sock == NULL) /* not mutex protected so check it inside too */
 		con->connect_action(con);
-	if (test_and_clear_bit(CF_WRITE_PENDING, &con->flags))
+	if (!list_empty(&con->writequeue))
 		send_to_sock(con);
 }
 
@@ -1632,11 +1643,25 @@ static int work_start(void)
 	return 0;
 }
 
+static void _stop_conn(struct connection *con, bool and_other)
+{
+	mutex_lock(&con->sock_mutex);
+	set_bit(CF_CLOSE, &con->flags);
+	set_bit(CF_READ_PENDING, &con->flags);
+	set_bit(CF_WRITE_PENDING, &con->flags);
+	if (con->sock && con->sock->sk) {
+		write_lock_bh(&con->sock->sk->sk_callback_lock);
+		con->sock->sk->sk_user_data = NULL;
+		write_unlock_bh(&con->sock->sk->sk_callback_lock);
+	}
+	if (con->othercon && and_other)
+		_stop_conn(con->othercon, false);
+	mutex_unlock(&con->sock_mutex);
+}
+
 static void stop_conn(struct connection *con)
 {
-	con->flags |= 0x0F;
+	_stop_conn(con, true);
-	if (con->sock && con->sock->sk)
-		con->sock->sk->sk_user_data = NULL;
 }
 
 static void free_conn(struct connection *con)
@@ -1648,6 +1673,36 @@ static void free_conn(struct connection *con)
 	kmem_cache_free(con_cache, con);
 }
 
+static void work_flush(void)
+{
+	int ok;
+	int i;
+	struct hlist_node *n;
+	struct connection *con;
+
+	flush_workqueue(recv_workqueue);
+	flush_workqueue(send_workqueue);
+	do {
+		ok = 1;
+		foreach_conn(stop_conn);
+		flush_workqueue(recv_workqueue);
+		flush_workqueue(send_workqueue);
+		for (i = 0; i < CONN_HASH_SIZE && ok; i++) {
+			hlist_for_each_entry_safe(con, n,
+						  &connection_hash[i], list) {
+				ok &= test_bit(CF_READ_PENDING, &con->flags);
+				ok &= test_bit(CF_WRITE_PENDING, &con->flags);
+				if (con->othercon) {
+					ok &= test_bit(CF_READ_PENDING,
+						       &con->othercon->flags);
+					ok &= test_bit(CF_WRITE_PENDING,
+						       &con->othercon->flags);
+				}
+			}
+		}
+	} while (!ok);
+}
+
 void dlm_lowcomms_stop(void)
 {
 	/* Set all the flags to prevent any
@@ -1655,11 +1710,10 @@ void dlm_lowcomms_stop(void)
 	*/
 	mutex_lock(&connections_lock);
 	dlm_allow_conn = 0;
-	foreach_conn(stop_conn);
+	mutex_unlock(&connections_lock);
+	work_flush();
 	clean_writequeues();
 	foreach_conn(free_conn);
-	mutex_unlock(&connections_lock);
-
 	work_stop();
 
 	kmem_cache_destroy(con_cache);

fs/dlm/rcom.c

@@ -155,6 +155,7 @@ int dlm_rcom_status(struct dlm_ls *ls, int nodeid, uint32_t status_flags)
 		goto out;
 	}
 
+retry:
 	error = create_rcom(ls, nodeid, DLM_RCOM_STATUS,
 			    sizeof(struct rcom_status), &rc, &mh);
 	if (error)
@@ -169,6 +170,8 @@ int dlm_rcom_status(struct dlm_ls *ls, int nodeid, uint32_t status_flags)
 
 	error = dlm_wait_function(ls, &rcom_response);
 	disallow_sync_reply(ls);
+	if (error == -ETIMEDOUT)
+		goto retry;
 	if (error)
 		goto out;
 
@@ -276,6 +279,7 @@ int dlm_rcom_names(struct dlm_ls *ls, int nodeid, char *last_name, int last_len)
 
 	ls->ls_recover_nodeid = nodeid;
 
+retry:
 	error = create_rcom(ls, nodeid, DLM_RCOM_NAMES, last_len, &rc, &mh);
 	if (error)
 		goto out;
@@ -288,6 +292,8 @@ int dlm_rcom_names(struct dlm_ls *ls, int nodeid, char *last_name, int last_len)
 
 	error = dlm_wait_function(ls, &rcom_response);
 	disallow_sync_reply(ls);
+	if (error == -ETIMEDOUT)
+		goto retry;
  out:
 	return error;
 }
@@ -332,25 +338,6 @@ int dlm_send_rcom_lookup(struct dlm_rsb *r, int dir_nodeid)
 	return error;
 }
 
-int dlm_send_rcom_lookup_dump(struct dlm_rsb *r, int to_nodeid)
-{
-	struct dlm_rcom *rc;
-	struct dlm_mhandle *mh;
-	struct dlm_ls *ls = r->res_ls;
-	int error;
-
-	error = create_rcom(ls, to_nodeid, DLM_RCOM_LOOKUP, r->res_length,
-			    &rc, &mh);
-	if (error)
-		goto out;
-	memcpy(rc->rc_buf, r->res_name, r->res_length);
-	rc->rc_id = 0xFFFFFFFF;
-
-	send_rcom(ls, mh, rc);
- out:
-	return error;
-}
-
 static void receive_rcom_lookup(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 {
 	struct dlm_rcom *rc;
@@ -362,6 +349,7 @@ static void receive_rcom_lookup(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 	if (error)
 		return;
 
+	/* Old code would send this special id to trigger a debug dump. */
 	if (rc_in->rc_id == 0xFFFFFFFF) {
 		log_error(ls, "receive_rcom_lookup dump from %d", nodeid);
 		dlm_dump_rsb_name(ls, rc_in->rc_buf, len);

fs/dlm/rcom.h

@@ -17,7 +17,6 @@
 int dlm_rcom_status(struct dlm_ls *ls, int nodeid, uint32_t status_flags);
 int dlm_rcom_names(struct dlm_ls *ls, int nodeid, char *last_name,int last_len);
 int dlm_send_rcom_lookup(struct dlm_rsb *r, int dir_nodeid);
-int dlm_send_rcom_lookup_dump(struct dlm_rsb *r, int to_nodeid);
 int dlm_send_rcom_lock(struct dlm_rsb *r, struct dlm_lkb *lkb);
 void dlm_receive_rcom(struct dlm_ls *ls, struct dlm_rcom *rc, int nodeid);
 int dlm_send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in);

fs/dlm/recover.c

@@ -52,6 +52,10 @@ int dlm_wait_function(struct dlm_ls *ls, int (*testfn) (struct dlm_ls *ls))
 					dlm_config.ci_recover_timer * HZ);
 		if (rv)
 			break;
+		if (test_bit(LSFL_RCOM_WAIT, &ls->ls_flags)) {
+			log_debug(ls, "dlm_wait_function timed out");
+			return -ETIMEDOUT;
+		}
 	}
 
 	if (dlm_recovery_stopped(ls)) {

fs/dlm/recoverd.c

@@ -287,11 +287,23 @@ static int dlm_recoverd(void *arg)
 	set_bit(LSFL_RECOVER_LOCK, &ls->ls_flags);
 	wake_up(&ls->ls_recover_lock_wait);
 
-	while (!kthread_should_stop()) {
+	while (1) {
+		/*
+		 * We call kthread_should_stop() after set_current_state().
+		 * This is because it works correctly if kthread_stop() is
+		 * called just before set_current_state().
+		 */
 		set_current_state(TASK_INTERRUPTIBLE);
+		if (kthread_should_stop()) {
+			set_current_state(TASK_RUNNING);
+			break;
+		}
 		if (!test_bit(LSFL_RECOVER_WORK, &ls->ls_flags) &&
-		    !test_bit(LSFL_RECOVER_DOWN, &ls->ls_flags))
+		    !test_bit(LSFL_RECOVER_DOWN, &ls->ls_flags)) {
+			if (kthread_should_stop())
+				break;
 			schedule();
+		}
 		set_current_state(TASK_RUNNING);
 
 		if (test_and_clear_bit(LSFL_RECOVER_DOWN, &ls->ls_flags)) {