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, 8 insertions, 0 deletions

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 4ad47d9f9d27..3908296d103f 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -285,6 +285,14 @@ static inline int inet_csk_reqsk_queue_is_full(const struct sock *sk)
 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req);
 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req);
 
+static inline unsigned long
+reqsk_timeout(struct request_sock *req, unsigned long max_timeout)
+{
+	u64 timeout = (u64)req->timeout << req->num_timeout;
+
+	return (unsigned long)min_t(u64, timeout, max_timeout);
+}
+
 static inline void inet_csk_prepare_for_destroy_sock(struct sock *sk)
 {
 	/* The below has to be done to allow calling inet_csk_destroy_sock */