From: Greg Jumper <[email protected]> The function rds_tcp_get_peer_sport() should return the peer port of a socket, even when the socket is not currently connected, so that RDS can reliably determine the MPRDS "lane" corresponding to the port.
rds_tcp_get_peer_sport() calls kernel_getpeername() to get the port number; however, when paths between endpoints frequently drop and reconnect, kernel_getpeername() can return -ENOTCONN, causing rds_tcp_get_peer_sport() to return an error, and ultimately causing RDS to use the wrong lane for a port when reconnecting to a peer. This patch modifies rds_tcp_get_peer_sport() to directly call the socket-specific get-name function (inet_getname() in this case) that kernel_getpeername() also calls. The socket-specific function offers an additional argument which, when set to a value greater than 1, causes the function to return the socket's peer name even when the socket is not connected, which in turn allows rds_tcp_get_peer_sport() to return the correct port number. Signed-off-by: Greg Jumper <[email protected]> Signed-off-by: Allison Henderson <[email protected]> --- net/rds/tcp_listen.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c index f2c4778be0b3..ba283c8ffa64 100644 --- a/net/rds/tcp_listen.c +++ b/net/rds/tcp_listen.c @@ -67,7 +67,14 @@ rds_tcp_get_peer_sport(struct socket *sock) } saddr; int sport; - if (kernel_getpeername(sock, &saddr.addr) >= 0) { + /* Call the socket's getname() function (inet_getname() in this case) + * with a final argument greater than 1 to get the peer's port + * regardless of whether the socket is currently connected. + * Using peer=2 will get the peer port even during reconnection states + * (TCPF_CLOSE, TCPF_SYN_SENT). This avoids -ENOTCONN while + * inet_dport still contains the correct peer port. + */ + if (sock->ops->getname(sock, &saddr.addr, 2) >= 0) { switch (saddr.addr.sa_family) { case AF_INET: sport = ntohs(saddr.sin.sin_port); @@ -177,7 +184,7 @@ void rds_tcp_conn_slots_available(struct rds_connection *conn, bool fan_out) if (fan_out) /* Delegate fan-out to a background worker in order - * to allow "kernel_getpeername" to acquire a lock + * to allow "sock->ops->getname()" to acquire a lock * on the socket. * The socket is already locked in this context * by either "rds_tcp_recv_path" or "tcp_v{4,6}_rcv", -- 2.43.0
