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An arbitration scheme for duelling SYNs is implemented as part of
commit 241b271952 ("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>
95 lines
2.8 KiB
C
95 lines
2.8 KiB
C
#ifndef _RDS_TCP_H
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#define _RDS_TCP_H
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#define RDS_TCP_PORT 16385
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struct rds_tcp_incoming {
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struct rds_incoming ti_inc;
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struct sk_buff_head ti_skb_list;
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};
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struct rds_tcp_connection {
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struct list_head t_tcp_node;
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struct rds_connection *conn;
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/* t_conn_lock synchronizes the connection establishment between
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* rds_tcp_accept_one and rds_tcp_conn_connect
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*/
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struct mutex t_conn_lock;
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struct socket *t_sock;
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void *t_orig_write_space;
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void *t_orig_data_ready;
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void *t_orig_state_change;
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struct rds_tcp_incoming *t_tinc;
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size_t t_tinc_hdr_rem;
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size_t t_tinc_data_rem;
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/* XXX error report? */
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struct work_struct t_conn_w;
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struct work_struct t_send_w;
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struct work_struct t_down_w;
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struct work_struct t_recv_w;
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/* for info exporting only */
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struct list_head t_list_item;
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u32 t_last_sent_nxt;
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u32 t_last_expected_una;
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u32 t_last_seen_una;
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};
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struct rds_tcp_statistics {
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uint64_t s_tcp_data_ready_calls;
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uint64_t s_tcp_write_space_calls;
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uint64_t s_tcp_sndbuf_full;
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uint64_t s_tcp_connect_raced;
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uint64_t s_tcp_listen_closed_stale;
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};
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/* tcp.c */
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void rds_tcp_tune(struct socket *sock);
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void rds_tcp_nonagle(struct socket *sock);
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void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn);
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void rds_tcp_restore_callbacks(struct socket *sock,
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struct rds_tcp_connection *tc);
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u32 rds_tcp_snd_nxt(struct rds_tcp_connection *tc);
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u32 rds_tcp_snd_una(struct rds_tcp_connection *tc);
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u64 rds_tcp_map_seq(struct rds_tcp_connection *tc, u32 seq);
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extern struct rds_transport rds_tcp_transport;
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void rds_tcp_accept_work(struct sock *sk);
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/* tcp_connect.c */
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int rds_tcp_conn_connect(struct rds_connection *conn);
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void rds_tcp_conn_shutdown(struct rds_connection *conn);
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void rds_tcp_state_change(struct sock *sk);
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/* tcp_listen.c */
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struct socket *rds_tcp_listen_init(struct net *);
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void rds_tcp_listen_stop(struct socket *);
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void rds_tcp_listen_data_ready(struct sock *sk);
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int rds_tcp_accept_one(struct socket *sock);
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int rds_tcp_keepalive(struct socket *sock);
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/* tcp_recv.c */
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int rds_tcp_recv_init(void);
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void rds_tcp_recv_exit(void);
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void rds_tcp_data_ready(struct sock *sk);
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int rds_tcp_recv(struct rds_connection *conn);
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void rds_tcp_inc_free(struct rds_incoming *inc);
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int rds_tcp_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to);
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/* tcp_send.c */
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void rds_tcp_xmit_prepare(struct rds_connection *conn);
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void rds_tcp_xmit_complete(struct rds_connection *conn);
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int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
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unsigned int hdr_off, unsigned int sg, unsigned int off);
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void rds_tcp_write_space(struct sock *sk);
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/* tcp_stats.c */
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DECLARE_PER_CPU(struct rds_tcp_statistics, rds_tcp_stats);
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#define rds_tcp_stats_inc(member) rds_stats_inc_which(rds_tcp_stats, member)
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unsigned int rds_tcp_stats_info_copy(struct rds_info_iterator *iter,
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unsigned int avail);
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#endif
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