diff options
author | Sowmini Varadhan <sowmini.varadhan@oracle.com> | 2016-05-02 11:24:52 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2016-05-03 16:03:44 -0400 |
commit | bd7c5f983f3185b75cc23bdd5dbc3a676aef3d1e (patch) | |
tree | 42b348d05eaf5e948bd694bdbe390ebb6a9c354f /net/rds/tcp.h | |
parent | eb192840266fab3e3da644018121eed30153355d (diff) |
RDS: TCP: Synchronize accept() and connect() paths on t_conn_lock.
An arbitration scheme for duelling SYNs is implemented as part of
commit 241b271952eb ("RDS-TCP: Reset tcp callbacks if re-using an
outgoing socket in rds_tcp_accept_one()") which ensures that both nodes
involved will arrive at the same arbitration decision. However, this
needs to be synchronized with an outgoing SYN to be generated by
rds_tcp_conn_connect(). This commit achieves the synchronization
through the t_conn_lock mutex in struct rds_tcp_connection.
The rds_conn_state is checked in rds_tcp_conn_connect() after acquiring
the t_conn_lock mutex. A SYN is sent out only if the RDS connection is
not already UP (an UP would indicate that rds_tcp_accept_one() has
completed 3WH, so no SYN needs to be generated).
Similarly, the rds_conn_state is checked in rds_tcp_accept_one() after
acquiring the t_conn_lock mutex. The only acceptable states (to
allow continuation of the arbitration logic) are UP (i.e., outgoing SYN
was SYN-ACKed by peer after it sent us the SYN) or CONNECTING (we sent
outgoing SYN before we saw incoming SYN).
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds/tcp.h')
-rw-r--r-- | net/rds/tcp.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/net/rds/tcp.h b/net/rds/tcp.h index 64f873c0c6b6..41c228300525 100644 --- a/net/rds/tcp.h +++ b/net/rds/tcp.h @@ -12,6 +12,10 @@ struct rds_tcp_connection { struct list_head t_tcp_node; struct rds_connection *conn; + /* t_conn_lock synchronizes the connection establishment between + * rds_tcp_accept_one and rds_tcp_conn_connect + */ + struct mutex t_conn_lock; struct socket *t_sock; void *t_orig_write_space; void *t_orig_data_ready; |