Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 948 insertions, 0 deletions

diff --git a/net/rds/connection.c b/net/rds/connection.c
new file mode 100644
index 0000000000..b4cc699c5f
--- /dev/null
+++ b/net/rds/connection.c
@@ -0,0 +1,948 @@
+/*
+ * Copyright (c) 2006, 2018 Oracle and/or its affiliates. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - 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.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <net/ipv6.h>
+#include <net/inet6_hashtables.h>
+#include <net/addrconf.h>
+
+#include "rds.h"
+#include "loop.h"
+
+#define RDS_CONNECTION_HASH_BITS 12
+#define RDS_CONNECTION_HASH_ENTRIES (1 << RDS_CONNECTION_HASH_BITS)
+#define RDS_CONNECTION_HASH_MASK (RDS_CONNECTION_HASH_ENTRIES - 1)
+
+/* converting this to RCU is a chore for another day.. */
+static DEFINE_SPINLOCK(rds_conn_lock);
+static unsigned long rds_conn_count;
+static struct hlist_head rds_conn_hash[RDS_CONNECTION_HASH_ENTRIES];
+static struct kmem_cache *rds_conn_slab;
+
+static struct hlist_head *rds_conn_bucket(const struct in6_addr *laddr,
+					  const struct in6_addr *faddr)
+{
+	static u32 rds6_hash_secret __read_mostly;
+	static u32 rds_hash_secret __read_mostly;
+
+	u32 lhash, fhash, hash;
+
+	net_get_random_once(&rds_hash_secret, sizeof(rds_hash_secret));
+	net_get_random_once(&rds6_hash_secret, sizeof(rds6_hash_secret));
+
+	lhash = (__force u32)laddr->s6_addr32[3];
+#if IS_ENABLED(CONFIG_IPV6)
+	fhash = __ipv6_addr_jhash(faddr, rds6_hash_secret);
+#else
+	fhash = (__force u32)faddr->s6_addr32[3];
+#endif
+	hash = __inet_ehashfn(lhash, 0, fhash, 0, rds_hash_secret);
+
+	return &rds_conn_hash[hash & RDS_CONNECTION_HASH_MASK];
+}
+
+#define rds_conn_info_set(var, test, suffix) do {		\
+	if (test)						\
+		var |= RDS_INFO_CONNECTION_FLAG_##suffix;	\
+} while (0)
+
+/* rcu read lock must be held or the connection spinlock */
+static struct rds_connection *rds_conn_lookup(struct net *net,
+					      struct hlist_head *head,
+					      const struct in6_addr *laddr,
+					      const struct in6_addr *faddr,
+					      struct rds_transport *trans,
+					      u8 tos, int dev_if)
+{
+	struct rds_connection *conn, *ret = NULL;
+
+	hlist_for_each_entry_rcu(conn, head, c_hash_node) {
+		if (ipv6_addr_equal(&conn->c_faddr, faddr) &&
+		    ipv6_addr_equal(&conn->c_laddr, laddr) &&
+		    conn->c_trans == trans &&
+		    conn->c_tos == tos &&
+		    net == rds_conn_net(conn) &&
+		    conn->c_dev_if == dev_if) {
+			ret = conn;
+			break;
+		}
+	}
+	rdsdebug("returning conn %p for %pI6c -> %pI6c\n", ret,
+		 laddr, faddr);
+	return ret;
+}
+
+/*
+ * This is called by transports as they're bringing down a connection.
+ * It clears partial message state so that the transport can start sending
+ * and receiving over this connection again in the future.  It is up to
+ * the transport to have serialized this call with its send and recv.
+ */
+static void rds_conn_path_reset(struct rds_conn_path *cp)
+{
+	struct rds_connection *conn = cp->cp_conn;
+
+	rdsdebug("connection %pI6c to %pI6c reset\n",
+		 &conn->c_laddr, &conn->c_faddr);
+
+	rds_stats_inc(s_conn_reset);
+	rds_send_path_reset(cp);
+	cp->cp_flags = 0;
+
+	/* Do not clear next_rx_seq here, else we cannot distinguish
+	 * retransmitted packets from new packets, and will hand all
+	 * of them to the application. That is not consistent with the
+	 * reliability guarantees of RDS. */
+}
+
+static void __rds_conn_path_init(struct rds_connection *conn,
+				 struct rds_conn_path *cp, bool is_outgoing)
+{
+	spin_lock_init(&cp->cp_lock);
+	cp->cp_next_tx_seq = 1;
+	init_waitqueue_head(&cp->cp_waitq);
+	INIT_LIST_HEAD(&cp->cp_send_queue);
+	INIT_LIST_HEAD(&cp->cp_retrans);
+
+	cp->cp_conn = conn;
+	atomic_set(&cp->cp_state, RDS_CONN_DOWN);
+	cp->cp_send_gen = 0;
+	cp->cp_reconnect_jiffies = 0;
+	cp->cp_conn->c_proposed_version = RDS_PROTOCOL_VERSION;
+	INIT_DELAYED_WORK(&cp->cp_send_w, rds_send_worker);
+	INIT_DELAYED_WORK(&cp->cp_recv_w, rds_recv_worker);
+	INIT_DELAYED_WORK(&cp->cp_conn_w, rds_connect_worker);
+	INIT_WORK(&cp->cp_down_w, rds_shutdown_worker);
+	mutex_init(&cp->cp_cm_lock);
+	cp->cp_flags = 0;
+}
+
+/*
+ * There is only every one 'conn' for a given pair of addresses in the
+ * system at a time.  They contain messages to be retransmitted and so
+ * span the lifetime of the actual underlying transport connections.
+ *
+ * For now they are not garbage collected once they're created.  They
+ * are torn down as the module is removed, if ever.
+ */
+static struct rds_connection *__rds_conn_create(struct net *net,
+						const struct in6_addr *laddr,
+						const struct in6_addr *faddr,
+						struct rds_transport *trans,
+						gfp_t gfp, u8 tos,
+						int is_outgoing,
+						int dev_if)
+{
+	struct rds_connection *conn, *parent = NULL;
+	struct hlist_head *head = rds_conn_bucket(laddr, faddr);
+	struct rds_transport *loop_trans;
+	unsigned long flags;
+	int ret, i;
+	int npaths = (trans->t_mp_capable ? RDS_MPATH_WORKERS : 1);
+
+	rcu_read_lock();
+	conn = rds_conn_lookup(net, head, laddr, faddr, trans, tos, dev_if);
+	if (conn &&
+	    conn->c_loopback &&
+	    conn->c_trans != &rds_loop_transport &&
+	    ipv6_addr_equal(laddr, faddr) &&
+	    !is_outgoing) {
+		/* This is a looped back IB connection, and we're
+		 * called by the code handling the incoming connect.
+		 * We need a second connection object into which we
+		 * can stick the other QP. */
+		parent = conn;
+		conn = parent->c_passive;
+	}
+	rcu_read_unlock();
+	if (conn)
+		goto out;
+
+	conn = kmem_cache_zalloc(rds_conn_slab, gfp);
+	if (!conn) {
+		conn = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+	conn->c_path = kcalloc(npaths, sizeof(struct rds_conn_path), gfp);
+	if (!conn->c_path) {
+		kmem_cache_free(rds_conn_slab, conn);
+		conn = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	INIT_HLIST_NODE(&conn->c_hash_node);
+	conn->c_laddr = *laddr;
+	conn->c_isv6 = !ipv6_addr_v4mapped(laddr);
+	conn->c_faddr = *faddr;
+	conn->c_dev_if = dev_if;
+	conn->c_tos = tos;
+
+#if IS_ENABLED(CONFIG_IPV6)
+	/* If the local address is link local, set c_bound_if to be the
+	 * index used for this connection.  Otherwise, set it to 0 as
+	 * the socket is not bound to an interface.  c_bound_if is used
+	 * to look up a socket when a packet is received
+	 */
+	if (ipv6_addr_type(laddr) & IPV6_ADDR_LINKLOCAL)
+		conn->c_bound_if = dev_if;
+	else
+#endif
+		conn->c_bound_if = 0;
+
+	rds_conn_net_set(conn, net);
+
+	ret = rds_cong_get_maps(conn);
+	if (ret) {
+		kfree(conn->c_path);
+		kmem_cache_free(rds_conn_slab, conn);
+		conn = ERR_PTR(ret);
+		goto out;
+	}
+
+	/*
+	 * This is where a connection becomes loopback.  If *any* RDS sockets
+	 * can bind to the destination address then we'd rather the messages
+	 * flow through loopback rather than either transport.
+	 */
+	loop_trans = rds_trans_get_preferred(net, faddr, conn->c_dev_if);
+	if (loop_trans) {
+		rds_trans_put(loop_trans);
+		conn->c_loopback = 1;
+		if (trans->t_prefer_loopback) {
+			if (likely(is_outgoing)) {
+				/* "outgoing" connection to local address.
+				 * Protocol says it wants the connection
+				 * handled by the loopback transport.
+				 * This is what TCP does.
+				 */
+				trans = &rds_loop_transport;
+			} else {
+				/* No transport currently in use
+				 * should end up here, but if it
+				 * does, reset/destroy the connection.
+				 */
+				kfree(conn->c_path);
+				kmem_cache_free(rds_conn_slab, conn);
+				conn = ERR_PTR(-EOPNOTSUPP);
+				goto out;
+			}
+		}
+	}
+
+	conn->c_trans = trans;
+
+	init_waitqueue_head(&conn->c_hs_waitq);
+	for (i = 0; i < npaths; i++) {
+		__rds_conn_path_init(conn, &conn->c_path[i],
+				     is_outgoing);
+		conn->c_path[i].cp_index = i;
+	}
+	rcu_read_lock();
+	if (rds_destroy_pending(conn))
+		ret = -ENETDOWN;
+	else
+		ret = trans->conn_alloc(conn, GFP_ATOMIC);
+	if (ret) {
+		rcu_read_unlock();
+		kfree(conn->c_path);
+		kmem_cache_free(rds_conn_slab, conn);
+		conn = ERR_PTR(ret);
+		goto out;
+	}
+
+	rdsdebug("allocated conn %p for %pI6c -> %pI6c over %s %s\n",
+		 conn, laddr, faddr,
+		 strnlen(trans->t_name, sizeof(trans->t_name)) ?
+		 trans->t_name : "[unknown]", is_outgoing ? "(outgoing)" : "");
+
+	/*
+	 * Since we ran without holding the conn lock, someone could
+	 * have created the same conn (either normal or passive) in the
+	 * interim. We check while holding the lock. If we won, we complete
+	 * init and return our conn. If we lost, we rollback and return the
+	 * other one.
+	 */
+	spin_lock_irqsave(&rds_conn_lock, flags);
+	if (parent) {
+		/* Creating passive conn */
+		if (parent->c_passive) {
+			trans->conn_free(conn->c_path[0].cp_transport_data);
+			kfree(conn->c_path);
+			kmem_cache_free(rds_conn_slab, conn);
+			conn = parent->c_passive;
+		} else {
+			parent->c_passive = conn;
+			rds_cong_add_conn(conn);
+			rds_conn_count++;
+		}
+	} else {
+		/* Creating normal conn */
+		struct rds_connection *found;
+
+		found = rds_conn_lookup(net, head, laddr, faddr, trans,
+					tos, dev_if);
+		if (found) {
+			struct rds_conn_path *cp;
+			int i;
+
+			for (i = 0; i < npaths; i++) {
+				cp = &conn->c_path[i];
+				/* The ->conn_alloc invocation may have
+				 * allocated resource for all paths, so all
+				 * of them may have to be freed here.
+				 */
+				if (cp->cp_transport_data)
+					trans->conn_free(cp->cp_transport_data);
+			}
+			kfree(conn->c_path);
+			kmem_cache_free(rds_conn_slab, conn);
+			conn = found;
+		} else {
+			conn->c_my_gen_num = rds_gen_num;
+			conn->c_peer_gen_num = 0;
+			hlist_add_head_rcu(&conn->c_hash_node, head);
+			rds_cong_add_conn(conn);
+			rds_conn_count++;
+		}
+	}
+	spin_unlock_irqrestore(&rds_conn_lock, flags);
+	rcu_read_unlock();
+
+out:
+	return conn;
+}
+
+struct rds_connection *rds_conn_create(struct net *net,
+				       const struct in6_addr *laddr,
+				       const struct in6_addr *faddr,
+				       struct rds_transport *trans, u8 tos,
+				       gfp_t gfp, int dev_if)
+{
+	return __rds_conn_create(net, laddr, faddr, trans, gfp, tos, 0, dev_if);
+}
+EXPORT_SYMBOL_GPL(rds_conn_create);
+
+struct rds_connection *rds_conn_create_outgoing(struct net *net,
+						const struct in6_addr *laddr,
+						const struct in6_addr *faddr,
+						struct rds_transport *trans,
+						u8 tos, gfp_t gfp, int dev_if)
+{
+	return __rds_conn_create(net, laddr, faddr, trans, gfp, tos, 1, dev_if);
+}
+EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
+
+void rds_conn_shutdown(struct rds_conn_path *cp)
+{
+	struct rds_connection *conn = cp->cp_conn;
+
+	/* shut it down unless it's down already */
+	if (!rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
+		/*
+		 * Quiesce the connection mgmt handlers before we start tearing
+		 * things down. We don't hold the mutex for the entire
+		 * duration of the shutdown operation, else we may be
+		 * deadlocking with the CM handler. Instead, the CM event
+		 * handler is supposed to check for state DISCONNECTING
+		 */
+		mutex_lock(&cp->cp_cm_lock);
+		if (!rds_conn_path_transition(cp, RDS_CONN_UP,
+					      RDS_CONN_DISCONNECTING) &&
+		    !rds_conn_path_transition(cp, RDS_CONN_ERROR,
+					      RDS_CONN_DISCONNECTING)) {
+			rds_conn_path_error(cp,
+					    "shutdown called in state %d\n",
+					    atomic_read(&cp->cp_state));
+			mutex_unlock(&cp->cp_cm_lock);
+			return;
+		}
+		mutex_unlock(&cp->cp_cm_lock);
+
+		wait_event(cp->cp_waitq,
+			   !test_bit(RDS_IN_XMIT, &cp->cp_flags));
+		wait_event(cp->cp_waitq,
+			   !test_bit(RDS_RECV_REFILL, &cp->cp_flags));
+
+		conn->c_trans->conn_path_shutdown(cp);
+		rds_conn_path_reset(cp);
+
+		if (!rds_conn_path_transition(cp, RDS_CONN_DISCONNECTING,
+					      RDS_CONN_DOWN) &&
+		    !rds_conn_path_transition(cp, RDS_CONN_ERROR,
+					      RDS_CONN_DOWN)) {
+			/* This can happen - eg when we're in the middle of tearing
+			 * down the connection, and someone unloads the rds module.
+			 * Quite reproducible with loopback connections.
+			 * Mostly harmless.
+			 *
+			 * Note that this also happens with rds-tcp because
+			 * we could have triggered rds_conn_path_drop in irq
+			 * mode from rds_tcp_state change on the receipt of
+			 * a FIN, thus we need to recheck for RDS_CONN_ERROR
+			 * here.
+			 */
+			rds_conn_path_error(cp, "%s: failed to transition "
+					    "to state DOWN, current state "
+					    "is %d\n", __func__,
+					    atomic_read(&cp->cp_state));
+			return;
+		}
+	}
+
+	/* Then reconnect if it's still live.
+	 * The passive side of an IB loopback connection is never added
+	 * to the conn hash, so we never trigger a reconnect on this
+	 * conn - the reconnect is always triggered by the active peer. */
+	cancel_delayed_work_sync(&cp->cp_conn_w);
+	rcu_read_lock();
+	if (!hlist_unhashed(&conn->c_hash_node)) {
+		rcu_read_unlock();
+		rds_queue_reconnect(cp);
+	} else {
+		rcu_read_unlock();
+	}
+}
+
+/* destroy a single rds_conn_path. rds_conn_destroy() iterates over
+ * all paths using rds_conn_path_destroy()
+ */
+static void rds_conn_path_destroy(struct rds_conn_path *cp)
+{
+	struct rds_message *rm, *rtmp;
+
+	if (!cp->cp_transport_data)
+		return;
+
+	/* make sure lingering queued work won't try to ref the conn */
+	cancel_delayed_work_sync(&cp->cp_send_w);
+	cancel_delayed_work_sync(&cp->cp_recv_w);
+
+	rds_conn_path_drop(cp, true);
+	flush_work(&cp->cp_down_w);
+
+	/* tear down queued messages */
+	list_for_each_entry_safe(rm, rtmp,
+				 &cp->cp_send_queue,
+				 m_conn_item) {
+		list_del_init(&rm->m_conn_item);
+		BUG_ON(!list_empty(&rm->m_sock_item));
+		rds_message_put(rm);
+	}
+	if (cp->cp_xmit_rm)
+		rds_message_put(cp->cp_xmit_rm);
+
+	WARN_ON(delayed_work_pending(&cp->cp_send_w));
+	WARN_ON(delayed_work_pending(&cp->cp_recv_w));
+	WARN_ON(delayed_work_pending(&cp->cp_conn_w));
+	WARN_ON(work_pending(&cp->cp_down_w));
+
+	cp->cp_conn->c_trans->conn_free(cp->cp_transport_data);
+}
+
+/*
+ * Stop and free a connection.
+ *
+ * This can only be used in very limited circumstances.  It assumes that once
+ * the conn has been shutdown that no one else is referencing the connection.
+ * We can only ensure this in the rmmod path in the current code.
+ */
+void rds_conn_destroy(struct rds_connection *conn)
+{
+	unsigned long flags;
+	int i;
+	struct rds_conn_path *cp;
+	int npaths = (conn->c_trans->t_mp_capable ? RDS_MPATH_WORKERS : 1);
+
+	rdsdebug("freeing conn %p for %pI4 -> "
+		 "%pI4\n", conn, &conn->c_laddr,
+		 &conn->c_faddr);
+
+	/* Ensure conn will not be scheduled for reconnect */
+	spin_lock_irq(&rds_conn_lock);
+	hlist_del_init_rcu(&conn->c_hash_node);
+	spin_unlock_irq(&rds_conn_lock);
+	synchronize_rcu();
+
+	/* shut the connection down */
+	for (i = 0; i < npaths; i++) {
+		cp = &conn->c_path[i];
+		rds_conn_path_destroy(cp);
+		BUG_ON(!list_empty(&cp->cp_retrans));
+	}
+
+	/*
+	 * The congestion maps aren't freed up here.  They're
+	 * freed by rds_cong_exit() after all the connections
+	 * have been freed.
+	 */
+	rds_cong_remove_conn(conn);
+
+	kfree(conn->c_path);
+	kmem_cache_free(rds_conn_slab, conn);
+
+	spin_lock_irqsave(&rds_conn_lock, flags);
+	rds_conn_count--;
+	spin_unlock_irqrestore(&rds_conn_lock, flags);
+}
+EXPORT_SYMBOL_GPL(rds_conn_destroy);
+
+static void __rds_inc_msg_cp(struct rds_incoming *inc,
+			     struct rds_info_iterator *iter,
+			     void *saddr, void *daddr, int flip, bool isv6)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	if (isv6)
+		rds6_inc_info_copy(inc, iter, saddr, daddr, flip);
+	else
+#endif
+		rds_inc_info_copy(inc, iter, *(__be32 *)saddr,
+				  *(__be32 *)daddr, flip);
+}
+
+static void rds_conn_message_info_cmn(struct socket *sock, unsigned int len,
+				      struct rds_info_iterator *iter,
+				      struct rds_info_lengths *lens,
+				      int want_send, bool isv6)
+{
+	struct hlist_head *head;
+	struct list_head *list;
+	struct rds_connection *conn;
+	struct rds_message *rm;
+	unsigned int total = 0;
+	unsigned long flags;
+	size_t i;
+	int j;
+
+	if (isv6)
+		len /= sizeof(struct rds6_info_message);
+	else
+		len /= sizeof(struct rds_info_message);
+
+	rcu_read_lock();
+
+	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
+	     i++, head++) {
+		hlist_for_each_entry_rcu(conn, head, c_hash_node) {
+			struct rds_conn_path *cp;
+			int npaths;
+
+			if (!isv6 && conn->c_isv6)
+				continue;
+
+			npaths = (conn->c_trans->t_mp_capable ?
+				 RDS_MPATH_WORKERS : 1);
+
+			for (j = 0; j < npaths; j++) {
+				cp = &conn->c_path[j];
+				if (want_send)
+					list = &cp->cp_send_queue;
+				else
+					list = &cp->cp_retrans;
+
+				spin_lock_irqsave(&cp->cp_lock, flags);
+
+				/* XXX too lazy to maintain counts.. */
+				list_for_each_entry(rm, list, m_conn_item) {
+					total++;
+					if (total <= len)
+						__rds_inc_msg_cp(&rm->m_inc,
+								 iter,
+								 &conn->c_laddr,
+								 &conn->c_faddr,
+								 0, isv6);
+				}
+
+				spin_unlock_irqrestore(&cp->cp_lock, flags);
+			}
+		}
+	}
+	rcu_read_unlock();
+
+	lens->nr = total;
+	if (isv6)
+		lens->each = sizeof(struct rds6_info_message);
+	else
+		lens->each = sizeof(struct rds_info_message);
+}
+
+static void rds_conn_message_info(struct socket *sock, unsigned int len,
+				  struct rds_info_iterator *iter,
+				  struct rds_info_lengths *lens,
+				  int want_send)
+{
+	rds_conn_message_info_cmn(sock, len, iter, lens, want_send, false);
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static void rds6_conn_message_info(struct socket *sock, unsigned int len,
+				   struct rds_info_iterator *iter,
+				   struct rds_info_lengths *lens,
+				   int want_send)
+{
+	rds_conn_message_info_cmn(sock, len, iter, lens, want_send, true);
+}
+#endif
+
+static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
+				       struct rds_info_iterator *iter,
+				       struct rds_info_lengths *lens)
+{
+	rds_conn_message_info(sock, len, iter, lens, 1);
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static void rds6_conn_message_info_send(struct socket *sock, unsigned int len,
+					struct rds_info_iterator *iter,
+					struct rds_info_lengths *lens)
+{
+	rds6_conn_message_info(sock, len, iter, lens, 1);
+}
+#endif
+
+static void rds_conn_message_info_retrans(struct socket *sock,
+					  unsigned int len,
+					  struct rds_info_iterator *iter,
+					  struct rds_info_lengths *lens)
+{
+	rds_conn_message_info(sock, len, iter, lens, 0);
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static void rds6_conn_message_info_retrans(struct socket *sock,
+					   unsigned int len,
+					   struct rds_info_iterator *iter,
+					   struct rds_info_lengths *lens)
+{
+	rds6_conn_message_info(sock, len, iter, lens, 0);
+}
+#endif
+
+void rds_for_each_conn_info(struct socket *sock, unsigned int len,
+			  struct rds_info_iterator *iter,
+			  struct rds_info_lengths *lens,
+			  int (*visitor)(struct rds_connection *, void *),
+			  u64 *buffer,
+			  size_t item_len)
+{
+	struct hlist_head *head;
+	struct rds_connection *conn;
+	size_t i;
+
+	rcu_read_lock();
+
+	lens->nr = 0;
+	lens->each = item_len;
+
+	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
+	     i++, head++) {
+		hlist_for_each_entry_rcu(conn, head, c_hash_node) {
+
+			/* XXX no c_lock usage.. */
+			if (!visitor(conn, buffer))
+				continue;
+
+			/* We copy as much as we can fit in the buffer,
+			 * but we count all items so that the caller
+			 * can resize the buffer. */
+			if (len >= item_len) {
+				rds_info_copy(iter, buffer, item_len);
+				len -= item_len;
+			}
+			lens->nr++;
+		}
+	}
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
+
+static void rds_walk_conn_path_info(struct socket *sock, unsigned int len,
+				    struct rds_info_iterator *iter,
+				    struct rds_info_lengths *lens,
+				    int (*visitor)(struct rds_conn_path *, void *),
+				    u64 *buffer,
+				    size_t item_len)
+{
+	struct hlist_head *head;
+	struct rds_connection *conn;
+	size_t i;
+
+	rcu_read_lock();
+
+	lens->nr = 0;
+	lens->each = item_len;
+
+	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
+	     i++, head++) {
+		hlist_for_each_entry_rcu(conn, head, c_hash_node) {
+			struct rds_conn_path *cp;
+
+			/* XXX We only copy the information from the first
+			 * path for now.  The problem is that if there are
+			 * more than one underlying paths, we cannot report
+			 * information of all of them using the existing
+			 * API.  For example, there is only one next_tx_seq,
+			 * which path's next_tx_seq should we report?  It is
+			 * a bug in the design of MPRDS.
+			 */
+			cp = conn->c_path;
+
+			/* XXX no cp_lock usage.. */
+			if (!visitor(cp, buffer))
+				continue;
+
+			/* We copy as much as we can fit in the buffer,
+			 * but we count all items so that the caller
+			 * can resize the buffer.
+			 */
+			if (len >= item_len) {
+				rds_info_copy(iter, buffer, item_len);
+				len -= item_len;
+			}
+			lens->nr++;
+		}
+	}
+	rcu_read_unlock();
+}
+
+static int rds_conn_info_visitor(struct rds_conn_path *cp, void *buffer)
+{
+	struct rds_info_connection *cinfo = buffer;
+	struct rds_connection *conn = cp->cp_conn;
+
+	if (conn->c_isv6)
+		return 0;
+
+	cinfo->next_tx_seq = cp->cp_next_tx_seq;
+	cinfo->next_rx_seq = cp->cp_next_rx_seq;
+	cinfo->laddr = conn->c_laddr.s6_addr32[3];
+	cinfo->faddr = conn->c_faddr.s6_addr32[3];
+	cinfo->tos = conn->c_tos;
+	strncpy(cinfo->transport, conn->c_trans->t_name,
+		sizeof(cinfo->transport));
+	cinfo->flags = 0;
+
+	rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &cp->cp_flags),
+			  SENDING);
+	/* XXX Future: return the state rather than these funky bits */
+	rds_conn_info_set(cinfo->flags,
+			  atomic_read(&cp->cp_state) == RDS_CONN_CONNECTING,
+			  CONNECTING);
+	rds_conn_info_set(cinfo->flags,
+			  atomic_read(&cp->cp_state) == RDS_CONN_UP,
+			  CONNECTED);
+	return 1;
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static int rds6_conn_info_visitor(struct rds_conn_path *cp, void *buffer)
+{
+	struct rds6_info_connection *cinfo6 = buffer;
+	struct rds_connection *conn = cp->cp_conn;
+
+	cinfo6->next_tx_seq = cp->cp_next_tx_seq;
+	cinfo6->next_rx_seq = cp->cp_next_rx_seq;
+	cinfo6->laddr = conn->c_laddr;
+	cinfo6->faddr = conn->c_faddr;
+	strncpy(cinfo6->transport, conn->c_trans->t_name,
+		sizeof(cinfo6->transport));
+	cinfo6->flags = 0;
+
+	rds_conn_info_set(cinfo6->flags, test_bit(RDS_IN_XMIT, &cp->cp_flags),
+			  SENDING);
+	/* XXX Future: return the state rather than these funky bits */
+	rds_conn_info_set(cinfo6->flags,
+			  atomic_read(&cp->cp_state) == RDS_CONN_CONNECTING,
+			  CONNECTING);
+	rds_conn_info_set(cinfo6->flags,
+			  atomic_read(&cp->cp_state) == RDS_CONN_UP,
+			  CONNECTED);
+	/* Just return 1 as there is no error case. This is a helper function
+	 * for rds_walk_conn_path_info() and it wants a return value.
+	 */
+	return 1;
+}
+#endif
+
+static void rds_conn_info(struct socket *sock, unsigned int len,
+			  struct rds_info_iterator *iter,
+			  struct rds_info_lengths *lens)
+{
+	u64 buffer[(sizeof(struct rds_info_connection) + 7) / 8];
+
+	rds_walk_conn_path_info(sock, len, iter, lens,
+				rds_conn_info_visitor,
+				buffer,
+				sizeof(struct rds_info_connection));
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static void rds6_conn_info(struct socket *sock, unsigned int len,
+			   struct rds_info_iterator *iter,
+			   struct rds_info_lengths *lens)
+{
+	u64 buffer[(sizeof(struct rds6_info_connection) + 7) / 8];
+
+	rds_walk_conn_path_info(sock, len, iter, lens,
+				rds6_conn_info_visitor,
+				buffer,
+				sizeof(struct rds6_info_connection));
+}
+#endif
+
+int rds_conn_init(void)
+{
+	int ret;
+
+	ret = rds_loop_net_init(); /* register pernet callback */
+	if (ret)
+		return ret;
+
+	rds_conn_slab = kmem_cache_create("rds_connection",
+					  sizeof(struct rds_connection),
+					  0, 0, NULL);
+	if (!rds_conn_slab) {
+		rds_loop_net_exit();
+		return -ENOMEM;
+	}
+
+	rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
+	rds_info_register_func(RDS_INFO_SEND_MESSAGES,
+			       rds_conn_message_info_send);
+	rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
+			       rds_conn_message_info_retrans);
+#if IS_ENABLED(CONFIG_IPV6)
+	rds_info_register_func(RDS6_INFO_CONNECTIONS, rds6_conn_info);
+	rds_info_register_func(RDS6_INFO_SEND_MESSAGES,
+			       rds6_conn_message_info_send);
+	rds_info_register_func(RDS6_INFO_RETRANS_MESSAGES,
+			       rds6_conn_message_info_retrans);
+#endif
+	return 0;
+}
+
+void rds_conn_exit(void)
+{
+	rds_loop_net_exit(); /* unregister pernet callback */
+	rds_loop_exit();
+
+	WARN_ON(!hlist_empty(rds_conn_hash));
+
+	kmem_cache_destroy(rds_conn_slab);
+
+	rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
+	rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
+				 rds_conn_message_info_send);
+	rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
+				 rds_conn_message_info_retrans);
+#if IS_ENABLED(CONFIG_IPV6)
+	rds_info_deregister_func(RDS6_INFO_CONNECTIONS, rds6_conn_info);
+	rds_info_deregister_func(RDS6_INFO_SEND_MESSAGES,
+				 rds6_conn_message_info_send);
+	rds_info_deregister_func(RDS6_INFO_RETRANS_MESSAGES,
+				 rds6_conn_message_info_retrans);
+#endif
+}
+
+/*
+ * Force a disconnect
+ */
+void rds_conn_path_drop(struct rds_conn_path *cp, bool destroy)
+{
+	atomic_set(&cp->cp_state, RDS_CONN_ERROR);
+
+	rcu_read_lock();
+	if (!destroy && rds_destroy_pending(cp->cp_conn)) {
+		rcu_read_unlock();
+		return;
+	}
+	queue_work(rds_wq, &cp->cp_down_w);
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(rds_conn_path_drop);
+
+void rds_conn_drop(struct rds_connection *conn)
+{
+	WARN_ON(conn->c_trans->t_mp_capable);
+	rds_conn_path_drop(&conn->c_path[0], false);
+}
+EXPORT_SYMBOL_GPL(rds_conn_drop);
+
+/*
+ * If the connection is down, trigger a connect. We may have scheduled a
+ * delayed reconnect however - in this case we should not interfere.
+ */
+void rds_conn_path_connect_if_down(struct rds_conn_path *cp)
+{
+	rcu_read_lock();
+	if (rds_destroy_pending(cp->cp_conn)) {
+		rcu_read_unlock();
+		return;
+	}
+	if (rds_conn_path_state(cp) == RDS_CONN_DOWN &&
+	    !test_and_set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags))
+		queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(rds_conn_path_connect_if_down);
+
+/* Check connectivity of all paths
+ */
+void rds_check_all_paths(struct rds_connection *conn)
+{
+	int i = 0;
+
+	do {
+		rds_conn_path_connect_if_down(&conn->c_path[i]);
+	} while (++i < conn->c_npaths);
+}
+
+void rds_conn_connect_if_down(struct rds_connection *conn)
+{
+	WARN_ON(conn->c_trans->t_mp_capable);
+	rds_conn_path_connect_if_down(&conn->c_path[0]);
+}
+EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);
+
+void
+__rds_conn_path_error(struct rds_conn_path *cp, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vprintk(fmt, ap);
+	va_end(ap);
+
+	rds_conn_path_drop(cp, false);
+}