1 files changed, 18 insertions, 0 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 54f212ce8aaf..e5319495f15e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1252,6 +1252,24 @@ static inline struct sk_buff *tcp_write_queue_prev(struct sock *sk, struct sk_bu
 #define tcp_for_write_queue_from_safe(skb, tmp, sk)                     \
         skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
 
+static inline bool retransmits_timed_out(const struct sock *sk,
+                                         unsigned int boundary)
+{
+        int limit, K;
+        if (!inet_csk(sk)->icsk_retransmits)
+                return false;
+
+        K = ilog2(TCP_RTO_MAX/TCP_RTO_MIN);
+
+        if (boundary <= K)
+                limit = ((2 << boundary) - 1) * TCP_RTO_MIN;
+        else
+                limit = ((2 << K) - 1) * TCP_RTO_MIN +
+                        (boundary - K) * TCP_RTO_MAX;
+
+        return (tcp_time_stamp - tcp_sk(sk)->retrans_stamp) >= limit;
+}
+
 static inline struct sk_buff *tcp_send_head(struct sock *sk)
 {
         return sk->sk_send_head;