When running RDS over TCP, the active (client) side connects to the
listening ("passive") side at the RDS_TCP_PORT. After the connection
is established, if the client side reboots (potentially without even
sending a FIN) the server still has a TCP socket in the Established
state. If the server-side now gets a new SYN comes from the client
with a different client port, TCP will create a new socket-pair, but
the RDS layer will incorrectly pull up the old rds_connection (which
is still associated with the stale t_sock and RDS socket state).
This patch corrects this behavior by having rds_tcp_accept_one()
always create a new connection for an incoming TCP SYN.
The rds and tcp state associated with the old socket-pair is cleaned
up in rds_tcp_set_callbacks() (i.e., rds_conn_drop on the old
connection)
Signed-off-by: Sowmini Varadhan <[email protected]>
---
net/rds/connection.c | 4 +++
net/rds/tcp.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++-
net/rds/tcp.h | 5 +++-
net/rds/tcp_connect.c | 2 +-
net/rds/tcp_listen.c | 13 +++++++++++-
5 files changed, 71 insertions(+), 4 deletions(-)
diff --git a/net/rds/connection.c b/net/rds/connection.c
index 14f0413..60f0cd6 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -126,7 +126,10 @@ static struct rds_connection *__rds_conn_create(__be32
laddr, __be32 faddr,
struct rds_transport *loop_trans;
unsigned long flags;
int ret;
+ struct rds_transport *otrans = trans;
+ if (!is_outgoing && otrans->t_type == RDS_TRANS_TCP)
+ goto new_conn;
rcu_read_lock();
conn = rds_conn_lookup(head, laddr, faddr, trans);
if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
@@ -142,6 +145,7 @@ static struct rds_connection *__rds_conn_create(__be32
laddr, __be32 faddr,
if (conn)
goto out;
+new_conn:
conn = kmem_cache_zalloc(rds_conn_slab, gfp);
if (!conn) {
conn = ERR_PTR(-ENOMEM);
diff --git a/net/rds/tcp.c b/net/rds/tcp.c
index edac9ef..dc50057 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -113,12 +113,48 @@ void rds_tcp_restore_callbacks(struct socket *sock,
write_unlock_bh(&sock->sk->sk_callback_lock);
}
+#define RDS_TCP_HASH_BITS 12
+#define RDS_TCP_HASH_ENTRIES (1 << RDS_TCP_HASH_BITS)
+#define RDS_TCP_HASH_MASK (RDS_TCP_HASH_ENTRIES - 1)
+
+static struct hlist_head rds_tcp_conn_hash[RDS_TCP_HASH_ENTRIES];
+
+static struct hlist_head *rds_tcp_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));
+ hash = __inet_ehashfn(be32_to_cpu(laddr), 0,
+ be32_to_cpu(faddr), 0,
+ rds_hash_secret);
+ return &rds_tcp_conn_hash[hash & RDS_TCP_HASH_MASK];
+}
+
+static struct rds_tcp_connection *rds_tcp_conn_lookup(struct hlist_head *head,
+ __be32 laddr,
+ __be32 faddr)
+{
+ struct rds_tcp_connection *rs_tcp, *ret = NULL;
+
+ hlist_for_each_entry_rcu(rs_tcp, head, t_passive_conn) {
+ struct rds_connection *conn = rs_tcp->conn;
+
+ if (conn->c_faddr == faddr && conn->c_laddr == laddr) {
+ ret = rs_tcp;
+ break;
+ }
+ }
+ return ret;
+}
+
/*
* This is the only path that sets tc->t_sock. Send and receive trust that
* it is set. The RDS_CONN_CONNECTED bit protects those paths from being
* called while it isn't set.
*/
-void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn)
+void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn,
+ bool passive)
{
struct rds_tcp_connection *tc = conn->c_transport_data;
@@ -140,6 +176,18 @@ void rds_tcp_set_callbacks(struct socket *sock, struct
rds_connection *conn)
tc->t_orig_data_ready = sock->sk->sk_data_ready;
tc->t_orig_write_space = sock->sk->sk_write_space;
tc->t_orig_state_change = sock->sk->sk_state_change;
+ INIT_HLIST_NODE(&tc->t_passive_conn);
+ if (passive) {
+ __be32 laddr = inet_sk(sock->sk)->inet_saddr;
+ __be32 faddr = inet_sk(sock->sk)->inet_daddr;
+ struct hlist_head *head = rds_tcp_conn_bucket(laddr, faddr);
+ struct rds_tcp_connection *oconn;
+
+ oconn = rds_tcp_conn_lookup(head, laddr, faddr);
+ if (oconn)
+ rds_conn_drop(oconn->conn);
+ hlist_add_head_rcu(&tc->t_passive_conn, head);
+ }
sock->sk->sk_user_data = conn;
sock->sk->sk_data_ready = rds_tcp_data_ready;
@@ -228,6 +276,7 @@ static void rds_tcp_conn_free(void *arg)
spin_lock_irqsave(&rds_tcp_conn_lock, flags);
list_del(&tc->t_tcp_node);
spin_unlock_irqrestore(&rds_tcp_conn_lock, flags);
+ hlist_del_init_rcu(&tc->t_passive_conn);
kmem_cache_free(rds_tcp_conn_slab, tc);
}
diff --git a/net/rds/tcp.h b/net/rds/tcp.h
index 0dbdd37..a3b3926 100644
--- a/net/rds/tcp.h
+++ b/net/rds/tcp.h
@@ -32,6 +32,8 @@ struct rds_tcp_connection {
u32 t_last_sent_nxt;
u32 t_last_expected_una;
u32 t_last_seen_una;
+
+ struct hlist_node t_passive_conn;
};
struct rds_tcp_statistics {
@@ -45,7 +47,8 @@ struct rds_tcp_statistics {
/* tcp.c */
void rds_tcp_tune(struct socket *sock);
void rds_tcp_nonagle(struct socket *sock);
-void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn);
+void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn,
+ bool passive);
void rds_tcp_restore_callbacks(struct socket *sock,
struct rds_tcp_connection *tc);
u32 rds_tcp_snd_nxt(struct rds_tcp_connection *tc);
diff --git a/net/rds/tcp_connect.c b/net/rds/tcp_connect.c
index f9f564a..e13facb 100644
--- a/net/rds/tcp_connect.c
+++ b/net/rds/tcp_connect.c
@@ -103,7 +103,7 @@ int rds_tcp_conn_connect(struct rds_connection *conn)
* once we call connect() we can start getting callbacks and they
* own the socket
*/
- rds_tcp_set_callbacks(sock, conn);
+ rds_tcp_set_callbacks(sock, conn, false);
ret = sock->ops->connect(sock, (struct sockaddr *)&dest, sizeof(dest),
O_NONBLOCK);
diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c
index 23ab4dc..6b783f1 100644
--- a/net/rds/tcp_listen.c
+++ b/net/rds/tcp_listen.c
@@ -51,6 +51,7 @@ static int rds_tcp_accept_one(struct socket *sock)
struct rds_connection *conn;
int ret;
struct inet_sock *inet;
+ struct rds_tcp_connection *rs_tcp;
ret = sock_create_lite(sock->sk->sk_family, sock->sk->sk_type,
sock->sk->sk_protocol, &new_sock);
@@ -77,6 +78,16 @@ static int rds_tcp_accept_one(struct socket *sock)
ret = PTR_ERR(conn);
goto out;
}
+ /* An incoming SYN request came in, and TCP just accepted it.
+ * We always create a new conn for listen side of TCP, and do not
+ * add it to the c_hash_list.
+ *
+ * If the client reboots, this conn will need to be cleaned up.
+ * When we get a new connection request from the client,
+ * rds_tcp_set_callbacks() will do that cleanup
+ */
+ rs_tcp = (struct rds_tcp_connection *)conn->c_transport_data;
+ WARN_ON(!rs_tcp || rs_tcp->t_sock);
/*
* see the comment above rds_queue_delayed_reconnect()
@@ -91,7 +102,7 @@ static int rds_tcp_accept_one(struct socket *sock)
goto out;
}
- rds_tcp_set_callbacks(new_sock, conn);
+ rds_tcp_set_callbacks(new_sock, conn, true);
rds_connect_complete(conn);
new_sock = NULL;
ret = 0;
--
1.7.1
--
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