tcp: lack of available data can also cause TSO defer
tcp_tso_should_defer() can return true in three different cases : 1) We are cwnd-limited 2) We are rwnd-limited 3) We are application limited. Neal pointed out that my recent fix went too far, since it assumed that if we were not in 1) case, we must be rwnd-limited Fix this by properly populating the is_cwnd_limited and is_rwnd_limited booleans. After this change, we can finally move the silly check for FIN flag only for the application-limited case. The same move for EOR bit will be handled in net-next, since commit 1c09f7d0 ("tcp: do not try to defer skbs with eor mark (MSG_EOR)") is scheduled for linux-4.21 Tested by running 200 concurrent netperf -t TCP_RR -- -r 60000,100 and checking none of them was rwnd_limited in the chrono_stat output from "ss -ti" command. Fixes: 41727549 ("tcp: Do not underestimate rwnd_limited") Signed-off-by: Eric Dumazet <edumazet@google.com> Suggested-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Reviewed-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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