1 files changed, 126 insertions, 50 deletions

diff --git a/net/rds/connection.c b/net/rds/connection.c
index 278f607ab60..378c3a6acf8 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -32,11 +32,12 @@
  */
 #include <linux/kernel.h>
 #include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/export.h>
 #include <net/inet_hashtables.h>
 
 #include "rds.h"
 #include "loop.h"
-#include "rdma.h"
 
 #define RDS_CONNECTION_HASH_BITS 12
 #define RDS_CONNECTION_HASH_ENTRIES (1 << RDS_CONNECTION_HASH_BITS)
@@ -50,10 +51,16 @@ static struct kmem_cache *rds_conn_slab;
 
 static struct hlist_head *rds_conn_bucket(__be32 laddr, __be32 faddr)
 {
+	static u32 rds_hash_secret __read_mostly;
+
+	unsigned long hash;
+
+	net_get_random_once(&rds_hash_secret, sizeof(rds_hash_secret));
+
 	/* Pass NULL, don't need struct net for hash */
-	unsigned long hash = inet_ehashfn(NULL,
-					  be32_to_cpu(laddr), 0,
-					  be32_to_cpu(faddr), 0);
+	hash = __inet_ehashfn(be32_to_cpu(laddr), 0,
+			      be32_to_cpu(faddr), 0,
+			      rds_hash_secret);
 	return &rds_conn_hash[hash & RDS_CONNECTION_HASH_MASK];
 }
 
@@ -62,26 +69,14 @@ static struct hlist_head *rds_conn_bucket(__be32 laddr, __be32 faddr)
 		var |= RDS_INFO_CONNECTION_FLAG_##suffix;	\
 } while (0)
 
-static inline int rds_conn_is_sending(struct rds_connection *conn)
-{
-	int ret = 0;
-
-	if (!mutex_trylock(&conn->c_send_lock))
-		ret = 1;
-	else
-		mutex_unlock(&conn->c_send_lock);
-
-	return ret;
-}
-
+/* rcu read lock must be held or the connection spinlock */
 static struct rds_connection *rds_conn_lookup(struct hlist_head *head,
 					      __be32 laddr, __be32 faddr,
 					      struct rds_transport *trans)
 {
 	struct rds_connection *conn, *ret = NULL;
-	struct hlist_node *pos;
 
-	hlist_for_each_entry(conn, pos, head, c_hash_node) {
+	hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 		if (conn->c_faddr == faddr && conn->c_laddr == laddr &&
 				conn->c_trans == trans) {
 			ret = conn;
@@ -99,7 +94,7 @@ static struct rds_connection *rds_conn_lookup(struct hlist_head *head,
  * 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.
  */
-void rds_conn_reset(struct rds_connection *conn)
+static void rds_conn_reset(struct rds_connection *conn)
 {
 	rdsdebug("connection %pI4 to %pI4 reset\n",
 	  &conn->c_laddr, &conn->c_faddr);
@@ -128,10 +123,11 @@ static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 {
 	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;
 
-	spin_lock_irqsave(&rds_conn_lock, flags);
+	rcu_read_lock();
 	conn = rds_conn_lookup(head, laddr, faddr, trans);
 	if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
 	    !is_outgoing) {
@@ -142,12 +138,12 @@ static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 		parent = conn;
 		conn = parent->c_passive;
 	}
-	spin_unlock_irqrestore(&rds_conn_lock, flags);
+	rcu_read_unlock();
 	if (conn)
 		goto out;
 
 	conn = kmem_cache_zalloc(rds_conn_slab, gfp);
-	if (conn == NULL) {
+	if (!conn) {
 		conn = ERR_PTR(-ENOMEM);
 		goto out;
 	}
@@ -158,7 +154,7 @@ static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 	spin_lock_init(&conn->c_lock);
 	conn->c_next_tx_seq = 1;
 
-	mutex_init(&conn->c_send_lock);
+	init_waitqueue_head(&conn->c_waitq);
 	INIT_LIST_HEAD(&conn->c_send_queue);
 	INIT_LIST_HEAD(&conn->c_retrans);
 
@@ -174,7 +170,9 @@ static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 	 * can bind to the destination address then we'd rather the messages
 	 * flow through loopback rather than either transport.
 	 */
-	if (rds_trans_get_preferred(faddr)) {
+	loop_trans = rds_trans_get_preferred(faddr);
+	if (loop_trans) {
+		rds_trans_put(loop_trans);
 		conn->c_loopback = 1;
 		if (is_outgoing && trans->t_prefer_loopback) {
 			/* "outgoing" connection - and the transport
@@ -237,7 +235,7 @@ static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 			kmem_cache_free(rds_conn_slab, conn);
 			conn = found;
 		} else {
-			hlist_add_head(&conn->c_hash_node, head);
+			hlist_add_head_rcu(&conn->c_hash_node, head);
 			rds_cong_add_conn(conn);
 			rds_conn_count++;
 		}
@@ -262,21 +260,91 @@ struct rds_connection *rds_conn_create_outgoing(__be32 laddr, __be32 faddr,
 }
 EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
 
+void rds_conn_shutdown(struct rds_connection *conn)
+{
+	/* shut it down unless it's down already */
+	if (!rds_conn_transition(conn, 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(&conn->c_cm_lock);
+		if (!rds_conn_transition(conn, RDS_CONN_UP, RDS_CONN_DISCONNECTING)
+		 && !rds_conn_transition(conn, RDS_CONN_ERROR, RDS_CONN_DISCONNECTING)) {
+			rds_conn_error(conn, "shutdown called in state %d\n",
+					atomic_read(&conn->c_state));
+			mutex_unlock(&conn->c_cm_lock);
+			return;
+		}
+		mutex_unlock(&conn->c_cm_lock);
+
+		wait_event(conn->c_waitq,
+			   !test_bit(RDS_IN_XMIT, &conn->c_flags));
+
+		conn->c_trans->conn_shutdown(conn);
+		rds_conn_reset(conn);
+
+		if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, 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 reproduceable with loopback connections.
+			 * Mostly harmless.
+			 */
+			rds_conn_error(conn,
+				"%s: failed to transition to state DOWN, "
+				"current state is %d\n",
+				__func__,
+				atomic_read(&conn->c_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(&conn->c_conn_w);
+	rcu_read_lock();
+	if (!hlist_unhashed(&conn->c_hash_node)) {
+		rcu_read_unlock();
+		rds_queue_reconnect(conn);
+	} else {
+		rcu_read_unlock();
+	}
+}
+
+/*
+ * 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)
 {
 	struct rds_message *rm, *rtmp;
+	unsigned long flags;
 
 	rdsdebug("freeing conn %p for %pI4 -> "
 		 "%pI4\n", conn, &conn->c_laddr,
 		 &conn->c_faddr);
 
-	hlist_del_init(&conn->c_hash_node);
+	/* 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();
 
-	/* wait for the rds thread to shut it down */
-	atomic_set(&conn->c_state, RDS_CONN_ERROR);
-	cancel_delayed_work(&conn->c_conn_w);
-	queue_work(rds_wq, &conn->c_down_w);
-	flush_workqueue(rds_wq);
+	/* shut the connection down */
+	rds_conn_drop(conn);
+	flush_work(&conn->c_down_w);
+
+	/* make sure lingering queued work won't try to ref the conn */
+	cancel_delayed_work_sync(&conn->c_send_w);
+	cancel_delayed_work_sync(&conn->c_recv_w);
 
 	/* tear down queued messages */
 	list_for_each_entry_safe(rm, rtmp,
@@ -301,7 +369,9 @@ void rds_conn_destroy(struct rds_connection *conn)
 	BUG_ON(!list_empty(&conn->c_retrans));
 	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);
 
@@ -311,27 +381,26 @@ static void rds_conn_message_info(struct socket *sock, unsigned int len,
 				  int want_send)
 {
 	struct hlist_head *head;
-	struct hlist_node *pos;
 	struct list_head *list;
 	struct rds_connection *conn;
 	struct rds_message *rm;
-	unsigned long flags;
 	unsigned int total = 0;
+	unsigned long flags;
 	size_t i;
 
 	len /= sizeof(struct rds_info_message);
 
-	spin_lock_irqsave(&rds_conn_lock, flags);
+	rcu_read_lock();
 
 	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 	     i++, head++) {
-		hlist_for_each_entry(conn, pos, head, c_hash_node) {
+		hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 			if (want_send)
 				list = &conn->c_send_queue;
 			else
 				list = &conn->c_retrans;
 
-			spin_lock(&conn->c_lock);
+			spin_lock_irqsave(&conn->c_lock, flags);
 
 			/* XXX too lazy to maintain counts.. */
 			list_for_each_entry(rm, list, m_conn_item) {
@@ -342,11 +411,10 @@ static void rds_conn_message_info(struct socket *sock, unsigned int len,
 							  conn->c_faddr, 0);
 			}
 
-			spin_unlock(&conn->c_lock);
+			spin_unlock_irqrestore(&conn->c_lock, flags);
 		}
 	}
-
-	spin_unlock_irqrestore(&rds_conn_lock, flags);
+	rcu_read_unlock();
 
 	lens->nr = total;
 	lens->each = sizeof(struct rds_info_message);
@@ -375,20 +443,17 @@ void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 {
 	uint64_t buffer[(item_len + 7) / 8];
 	struct hlist_head *head;
-	struct hlist_node *pos;
-	struct hlist_node *tmp;
 	struct rds_connection *conn;
-	unsigned long flags;
 	size_t i;
 
-	spin_lock_irqsave(&rds_conn_lock, flags);
+	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_safe(conn, pos, tmp, head, c_hash_node) {
+		hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 
 			/* XXX no c_lock usage.. */
 			if (!visitor(conn, buffer))
@@ -404,8 +469,7 @@ void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 			lens->nr++;
 		}
 	}
-
-	spin_unlock_irqrestore(&rds_conn_lock, flags);
+	rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 
@@ -422,8 +486,8 @@ static int rds_conn_info_visitor(struct rds_connection *conn,
 		sizeof(cinfo->transport));
 	cinfo->flags = 0;
 
-	rds_conn_info_set(cinfo->flags,
-			  rds_conn_is_sending(conn), SENDING);
+	rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &conn->c_flags),
+			  SENDING);
 	/* XXX Future: return the state rather than these funky bits */
 	rds_conn_info_set(cinfo->flags,
 			  atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
@@ -443,12 +507,12 @@ static void rds_conn_info(struct socket *sock, unsigned int len,
 				sizeof(struct rds_info_connection));
 }
 
-int __init rds_conn_init(void)
+int rds_conn_init(void)
 {
 	rds_conn_slab = kmem_cache_create("rds_connection",
 					  sizeof(struct rds_connection),
 					  0, 0, NULL);
-	if (rds_conn_slab == NULL)
+	if (!rds_conn_slab)
 		return -ENOMEM;
 
 	rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
@@ -486,6 +550,18 @@ void rds_conn_drop(struct rds_connection *conn)
 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_connect_if_down(struct rds_connection *conn)
+{
+	if (rds_conn_state(conn) == RDS_CONN_DOWN &&
+	    !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
+		queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
+}
+EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);
+
+/*
  * An error occurred on the connection
  */
 void