diff options
| author | Yuchung Cheng <ycheng@google.com> | 2012-12-06 08:45:32 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-12-07 14:39:28 -0500 |
| commit | 93b174ad71b08e504c2cf6e8a58ecce778b77a40 (patch) | |
| tree | f9e7fd386880ae14d4625de9801a57c5bf5fa105 | |
| parent | 1afa471706963643ceeda7cbbe9c605a1e883d53 (diff) | |
| download | lwn-93b174ad71b08e504c2cf6e8a58ecce778b77a40.tar.gz lwn-93b174ad71b08e504c2cf6e8a58ecce778b77a40.zip | |
tcp: bug fix Fast Open client retransmission
If SYN-ACK partially acks SYN-data, the client retransmits the
remaining data by tcp_retransmit_skb(). This increments lost recovery
state variables like tp->retrans_out in Open state. If loss recovery
happens before the retransmission is acked, it triggers the WARN_ON
check in tcp_fastretrans_alert(). For example: the client sends
SYN-data, gets SYN-ACK acking only ISN, retransmits data, sends
another 4 data packets and get 3 dupacks.
Since the retransmission is not caused by network drop it should not
update the recovery state variables. Further the server may return a
smaller MSS than the cached MSS used for SYN-data, so the retranmission
needs a loop. Otherwise some data will not be retransmitted until timeout
or other loss recovery events.
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/tcp.h | 1 | ||||
| -rw-r--r-- | net/ipv4/tcp_input.c | 6 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 15 |
3 files changed, 16 insertions, 6 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index 6feeccd83dd7..4af45e33105d 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -525,6 +525,7 @@ static inline __u32 cookie_v6_init_sequence(struct sock *sk, extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, int nonagle); extern bool tcp_may_send_now(struct sock *sk); +extern int __tcp_retransmit_skb(struct sock *, struct sk_buff *); extern int tcp_retransmit_skb(struct sock *, struct sk_buff *); extern void tcp_retransmit_timer(struct sock *sk); extern void tcp_xmit_retransmit_queue(struct sock *); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 609ff98aeb47..181fc8234a52 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5645,7 +5645,11 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack, tcp_fastopen_cache_set(sk, mss, cookie, syn_drop); if (data) { /* Retransmit unacked data in SYN */ - tcp_retransmit_skb(sk, data); + tcp_for_write_queue_from(data, sk) { + if (data == tcp_send_head(sk) || + __tcp_retransmit_skb(sk, data)) + break; + } tcp_rearm_rto(sk); return true; } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 2798706cb063..948ac275b9b5 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2309,12 +2309,11 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, * state updates are done by the caller. Returns non-zero if an * error occurred which prevented the send. */ -int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) +int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) { struct tcp_sock *tp = tcp_sk(sk); struct inet_connection_sock *icsk = inet_csk(sk); unsigned int cur_mss; - int err; /* Inconslusive MTU probe */ if (icsk->icsk_mtup.probe_size) { @@ -2387,11 +2386,17 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) if (unlikely(NET_IP_ALIGN && ((unsigned long)skb->data & 3))) { struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); - err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : - -ENOBUFS; + return nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) : + -ENOBUFS; } else { - err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); + return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); } +} + +int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) +{ + struct tcp_sock *tp = tcp_sk(sk); + int err = __tcp_retransmit_skb(sk, skb); if (err == 0) { /* Update global TCP statistics. */ |