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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);