diff options
Diffstat (limited to 'net/ipv4/tcp_output.c')
| -rw-r--r-- | net/ipv4/tcp_output.c | 34 |
1 files changed, 26 insertions, 8 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 29dde97c3c41..20847de991ea 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -878,15 +878,8 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, BUG_ON(!skb || !tcp_skb_pcount(skb)); if (clone_it) { - const struct sk_buff *fclone = skb + 1; - skb_mstamp_get(&skb->skb_mstamp); - if (unlikely(skb->fclone == SKB_FCLONE_ORIG && - fclone->fclone == SKB_FCLONE_CLONE)) - NET_INC_STATS(sock_net(sk), - LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); - if (unlikely(skb_cloned(skb))) skb = pskb_copy(skb, gfp_mask); else @@ -2061,6 +2054,25 @@ bool tcp_schedule_loss_probe(struct sock *sk) return true; } +/* Thanks to skb fast clones, we can detect if a prior transmit of + * a packet is still in a qdisc or driver queue. + * In this case, there is very little point doing a retransmit ! + * Note: This is called from BH context only. + */ +static bool skb_still_in_host_queue(const struct sock *sk, + const struct sk_buff *skb) +{ + const struct sk_buff *fclone = skb + 1; + + if (unlikely(skb->fclone == SKB_FCLONE_ORIG && + fclone->fclone == SKB_FCLONE_CLONE)) { + NET_INC_STATS_BH(sock_net(sk), + LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); + return true; + } + return false; +} + /* When probe timeout (PTO) fires, send a new segment if one exists, else * retransmit the last segment. */ @@ -2086,6 +2098,9 @@ void tcp_send_loss_probe(struct sock *sk) if (WARN_ON(!skb)) goto rearm_timer; + if (skb_still_in_host_queue(sk, skb)) + goto rearm_timer; + pcount = tcp_skb_pcount(skb); if (WARN_ON(!pcount)) goto rearm_timer; @@ -2407,6 +2422,9 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) return -EAGAIN; + if (skb_still_in_host_queue(sk, skb)) + return -EBUSY; + if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) BUG(); @@ -2500,7 +2518,7 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) * see tcp_input.c tcp_sacktag_write_queue(). */ TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; - } else { + } else if (err != -EBUSY) { NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); } return err; |