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| author | Sowmini Varadhan <sowmini.varadhan@oracle.com> | 2015-10-11 16:49:44 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-10-13 04:22:41 -0700 |
| commit | 241b271952eb319622a6cc740a72abe41fc27ad6 (patch) | |
| tree | dc7ed0c61c8201ff72042f9ca407294c24545d94 /net/rds | |
| parent | 486798001b92eacbf9f809787a6348750c174035 (diff) | |
| download | linux-241b271952eb319622a6cc740a72abe41fc27ad6.tar.bz2 | |
RDS-TCP: Reset tcp callbacks if re-using an outgoing socket in rds_tcp_accept_one()
Consider the following "duelling syn" sequence between two peers A and B:
A B
SYN1 -->
<-- SYN2
SYN2ACK -->
Note that the SYN/ACK has already been sent out by TCP before
rds_tcp_accept_one() gets invoked as part of callbacks.
If the inet_addr(A) is numerically less than inet_addr(B),
the arbitration scheme in rds_tcp_accept_one() will prefer the
TCP connection triggered by SYN1, and will send a CLOSE for the
SYN2 (just after the SYN2ACK was sent).
Since B also follows the same arbitration scheme, it will send the SYN-ACK
for SYN1 that will set up a healthy ESTABLISHED connection on both sides.
B will also get a CLOSE for SYN2, which should result in the cleanup
of the TCP state machine for SYN2, but it should not trigger any
stale RDS-TCP callbacks (such as ->writespace, ->state_change etc),
that would disrupt the progress of the SYN2 based RDS-TCP connection.
Thus the arbitration scheme in rds_tcp_accept_one() should restore
rds_tcp callbacks for the winner before setting them up for the
new accept socket, and also make sure that conn->c_outgoing
is set to 0 so that we do not trigger any reconnect attempts on the
passive side of the tcp socket in the future, in conformance with
commit c82ac7e69efe ("net/rds: RDS-TCP: only initiate reconnect attempt
on outgoing TCP socket.")
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')
| -rw-r--r-- | net/rds/tcp_listen.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c index 1d90240e5d82..0936a4a32b47 100644 --- a/net/rds/tcp_listen.c +++ b/net/rds/tcp_listen.c @@ -125,6 +125,9 @@ int rds_tcp_accept_one(struct socket *sock) new_sock = NULL; ret = 0; goto out; + } else if (rs_tcp->t_sock) { + rds_tcp_restore_callbacks(rs_tcp->t_sock, rs_tcp); + conn->c_outgoing = 0; } rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING); |