path: root/net/ipv4/tcp_output.c
diff options
authorEric Dumazet <edumazet@google.com>2018-11-11 06:41:30 -0800
committerDavid S. Miller <davem@davemloft.net>2018-11-11 13:54:53 -0800
commitf1c6ea3827b5e5ec62e297bcf4ccfd065326e8f7 (patch)
tree69036d0cdbfb568233a8838bc1ff9f9b29ab624b /net/ipv4/tcp_output.c
parenttcp: do not try to defer skbs with eor mark (MSG_EOR) (diff)
tcp: refine tcp_tso_should_defer() after EDT adoption
tcp_tso_should_defer() last step tries to check if the probable next ACK packet is coming in less than half rtt. Problem is that the head->tstamp might be in the future, so we need to use signed arithmetics to avoid overflows. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_output.c')
1 files changed, 4 insertions, 3 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 35feadf48030..78a56cef7e39 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1907,10 +1907,11 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
bool *is_cwnd_limited, u32 max_segs)
const struct inet_connection_sock *icsk = inet_csk(sk);
- u32 age, send_win, cong_win, limit, in_flight;
+ u32 send_win, cong_win, limit, in_flight;
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *head;
int win_divisor;
+ s64 delta;
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
goto send_now;
@@ -1972,9 +1973,9 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
head = tcp_rtx_queue_head(sk);
if (!head)
goto send_now;
- age = tcp_stamp_us_delta(tp->tcp_mstamp, tcp_skb_timestamp_us(head));
+ delta = tp->tcp_clock_cache - head->tstamp;
/* If next ACK is likely to come too late (half srtt), do not defer */
- if (age < (tp->srtt_us >> 4))
+ if ((s64)(delta - (u64)NSEC_PER_USEC * (tp->srtt_us >> 4)) < 0)
goto send_now;
/* Ok, it looks like it is advisable to defer. */