+ /* If stream is thin, use linear timeouts. Since 'icsk_backoff' is
+ * used to reset timer, set to 0. Recalculate 'icsk_rto' as this
+ * might be increased if the stream oscillates between thin and thick,
+ * thus the old value might already be too high compared to the value
+ * set by 'tcp_set_rto' in tcp_input.c which resets the rto without
+ * backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating
+ * exponential backoff behaviour to avoid continue hammering
+ * linear-timeout retransmissions into a black hole
+ */
+ if (sk->sk_state == TCP_ESTABLISHED &&
+ (tp->thin_lto || sysctl_tcp_thin_linear_timeouts) &&
+ tcp_stream_is_thin(tp) &&
+ icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) {
+ icsk->icsk_backoff = 0;
+ icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX);
+ } else {
+ /* Use normal (exponential) backoff */
+ icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
+ }