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net/rds: RDS-TCP: Always create a new rds_sock for an incoming connection.

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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 esablished
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 via the rds_tcp_state_change() callback which would typically be
invoked in most cases when the client-TCP sends a FIN on TCP restart,
triggering a transition to CLOSE_WAIT state. In the rarer event of client
death without a FIN, TCP_KEEPALIVE probes on the socket will detect
the stale socket, and the TCP transition to CLOSE state will trigger
the RDS state cleanup.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sowmini Varadhan 2015-05-05 15:20:51 -04:00 committed by David S. Miller
parent e16e888b52
commit f711a6ae06
3 changed files with 51 additions and 0 deletions
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4
net/rds/connection.c
View File

@ -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);

1
net/rds/tcp_connect.c
View File

@ -62,6 +62,7 @@ void rds_tcp_state_change(struct sock *sk)
case TCP_ESTABLISHED:
rds_connect_complete(conn);
break;
case TCP_CLOSE_WAIT:
case TCP_CLOSE:
rds_conn_drop(conn);
default:

46
net/rds/tcp_listen.c
View File

@ -45,12 +45,45 @@ static void rds_tcp_accept_worker(struct work_struct *work);
static DECLARE_WORK(rds_tcp_listen_work, rds_tcp_accept_worker);
static struct socket *rds_tcp_listen_sock;
static int rds_tcp_keepalive(struct socket *sock)
{
/* values below based on xs_udp_default_timeout */
int keepidle = 5; /* send a probe 'keepidle' secs after last data */
int keepcnt = 5; /* number of unack'ed probes before declaring dead */
int keepalive = 1;
int ret = 0;
ret = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
(char *)&keepalive, sizeof(keepalive));
if (ret < 0)
goto bail;
ret = kernel_setsockopt(sock, IPPROTO_TCP, TCP_KEEPCNT,
(char *)&keepcnt, sizeof(keepcnt));
if (ret < 0)
goto bail;
ret = kernel_setsockopt(sock, IPPROTO_TCP, TCP_KEEPIDLE,
(char *)&keepidle, sizeof(keepidle));
if (ret < 0)
goto bail;
/* KEEPINTVL is the interval between successive probes. We follow
* the model in xs_tcp_finish_connecting() and re-use keepidle.
*/
ret = kernel_setsockopt(sock, IPPROTO_TCP, TCP_KEEPINTVL,
(char *)&keepidle, sizeof(keepidle));
bail:
return ret;
}
static int rds_tcp_accept_one(struct socket *sock)
{
struct socket *new_sock = NULL;
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);
@ -63,6 +96,10 @@ static int rds_tcp_accept_one(struct socket *sock)
if (ret < 0)
goto out;
ret = rds_tcp_keepalive(new_sock);
if (ret < 0)
goto out;
rds_tcp_tune(new_sock);
inet = inet_sk(new_sock->sk);
@ -77,6 +114,15 @@ 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.
* rds_tcp_state_change() 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()