*/
int mss = icsk->icsk_ack.rcv_mss;
int free_space = tcp_space(sk);
- int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk));
+ int allowed_space = tcp_full_space(sk);
+ int full_space = min_t(int, tp->window_clamp, allowed_space);
int window;
if (mss > full_space)
tp->rcv_ssthresh = min(tp->rcv_ssthresh,
4U * tp->advmss);
- if (free_space < mss)
+ /* free_space might become our new window, make sure we don't
+ * increase it due to wscale.
+ */
+ free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale);
+
+ /* if free space is less than mss estimate, or is below 1/16th
+ * of the maximum allowed, try to move to zero-window, else
+ * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and
+ * new incoming data is dropped due to memory limits.
+ * With large window, mss test triggers way too late in order
+ * to announce zero window in time before rmem limit kicks in.
+ */
+ if (free_space < (allowed_space >> 4) || free_space < mss)
return 0;
}