tcp: Use BPF timeout setting for SYN ACK RTO

When setting RTO through BPF program, some SYN ACK packets were unaffected
and continued to use TCP_TIMEOUT_INIT constant. This patch adds timeout
option to struct request_sock. Option is initialized with TCP_TIMEOUT_INIT
and is reassigned through BPF using tcp_timeout_init call. SYN ACK
retransmits now use newly added timeout option.

Signed-off-by: Akhmat Karakotov <hmukos@yandex-team.ru>
Acked-by: Martin KaFai Lau <kafai@fb.com>

v2:
	- Add timeout option to struct request_sock. Do not call
	  tcp_timeout_init on every syn ack retransmit.

v3:
	- Use unsigned long for min. Bound tcp_timeout_init to TCP_RTO_MAX.

v4:
	- Refactor duplicate code by adding reqsk_timeout function.
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 29e41ff3ec93..144c39db9898 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -70,6 +70,7 @@ struct request_sock {
 	struct saved_syn		*saved_syn;
 	u32				secid;
 	u32				peer_secid;
+	u32				timeout;
 };
 
 static inline struct request_sock *inet_reqsk(const struct sock *sk)
@@ -104,6 +105,7 @@ reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
 	sk_node_init(&req_to_sk(req)->sk_node);
 	sk_tx_queue_clear(req_to_sk(req));
 	req->saved_syn = NULL;
+	req->timeout = 0;
 	req->num_timeout = 0;
 	req->num_retrans = 0;
 	req->sk = NULL;