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authorEric Dumazet <edumazet@google.com>2021-03-11 21:35:05 +0100
committerDavid S. Miller <davem@davemloft.net>2021-03-12 03:35:31 +0100
commita7abf3cd76e1e190a2c22afe5ffd0f695c7641b0 (patch)
tree2b70863783d21ad6b50503bf27ca2e5a54555b8b /net/ipv4/tcp_input.c
parenttcp: plug skb_still_in_host_queue() to TSQ (diff)
downloadlinux-a7abf3cd76e1e190a2c22afe5ffd0f695c7641b0.tar.xz
linux-a7abf3cd76e1e190a2c22afe5ffd0f695c7641b0.zip
tcp: consider using standard rtx logic in tcp_rcv_fastopen_synack()
Jakub reported Data included in a Fastopen SYN that had to be retransmit would have to wait for an RTO if TX completions are slow, even with prior fix. This is because tcp_rcv_fastopen_synack() does not use standard rtx logic, meaning TSQ handler exits early in tcp_tsq_write() because tp->lost_out == tp->retrans_out Lets make tcp_rcv_fastopen_synack() use standard rtx logic, by using tcp_mark_skb_lost() on the skb thats needs to be sent again. Not this raised a warning in tcp_fastretrans_alert() during my tests since we consider the data not being aknowledged by the receiver does not mean packet was lost on the network. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Jakub Kicinski <kuba@kernel.org> Cc: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
-rw-r--r--net/ipv4/tcp_input.c10
1 files changed, 4 insertions, 6 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 69a545db80d2..4cf4dd532d1c 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2914,7 +2914,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,
/* D. Check state exit conditions. State can be terminated
* when high_seq is ACKed. */
if (icsk->icsk_ca_state == TCP_CA_Open) {
- WARN_ON(tp->retrans_out != 0);
+ WARN_ON(tp->retrans_out != 0 && !tp->syn_data);
tp->retrans_stamp = 0;
} else if (!before(tp->snd_una, tp->high_seq)) {
switch (icsk->icsk_ca_state) {
@@ -5994,11 +5994,9 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
tp->fastopen_client_fail = TFO_SYN_RETRANSMITTED;
else
tp->fastopen_client_fail = TFO_DATA_NOT_ACKED;
- skb_rbtree_walk_from(data) {
- if (__tcp_retransmit_skb(sk, data, 1))
- break;
- }
- tcp_rearm_rto(sk);
+ skb_rbtree_walk_from(data)
+ tcp_mark_skb_lost(sk, data);
+ tcp_xmit_retransmit_queue(sk);
NET_INC_STATS(sock_net(sk),
LINUX_MIB_TCPFASTOPENACTIVEFAIL);
return true;