diff options
| -rw-r--r-- | net/ipv4/tcp_input.c | 79 |
1 files changed, 62 insertions, 17 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 37e1c5c..bd7aef5 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4449,6 +4449,58 @@ static inline int tcp_try_rmem_schedule(struct sock *sk, unsigned int size) return 0; } +/** + * tcp_try_coalesce - try to merge skb to prior one + * @sk: socket + * @to: prior buffer + * @from: buffer to add in queue + * + * Before queueing skb @from after @to, try to merge them + * to reduce overall memory use and queue lengths, if cost is small. + * Packets in ofo or receive queues can stay a long time. + * Better try to coalesce them right now to avoid future collapses. + * Returns > 0 value if caller should free @from instead of queueing it + */ +static int tcp_try_coalesce(struct sock *sk, + struct sk_buff *to, + struct sk_buff *from) +{ + int len = from->len; + + if (tcp_hdr(from)->fin) + return 0; + if (len <= skb_tailroom(to)) { + BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len)); +merge: + NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRCVCOALESCE); + TCP_SKB_CB(to)->end_seq = TCP_SKB_CB(from)->end_seq; + TCP_SKB_CB(to)->ack_seq = TCP_SKB_CB(from)->ack_seq; + return 1; + } + if (skb_headlen(from) == 0 && + !skb_has_frag_list(to) && + !skb_has_frag_list(from) && + (skb_shinfo(to)->nr_frags + + skb_shinfo(from)->nr_frags <= MAX_SKB_FRAGS)) { + int delta = from->truesize - ksize(from->head) - + SKB_DATA_ALIGN(sizeof(struct sk_buff)); + + WARN_ON_ONCE(delta < len); + memcpy(skb_shinfo(to)->frags + skb_shinfo(to)->nr_frags, + skb_shinfo(from)->frags, + skb_shinfo(from)->nr_frags * sizeof(skb_frag_t)); + skb_shinfo(to)->nr_frags += skb_shinfo(from)->nr_frags; + skb_shinfo(from)->nr_frags = 0; + to->truesize += delta; + atomic_add(delta, &sk->sk_rmem_alloc); + sk_mem_charge(sk, delta); + to->len += len; + to->data_len += len; + goto merge; + } + return 0; +} + static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb) { struct tcp_sock *tp = tcp_sk(sk); @@ -4487,23 +4539,11 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb) end_seq = TCP_SKB_CB(skb)->end_seq; if (seq == TCP_SKB_CB(skb1)->end_seq) { - /* Packets in ofo can stay in queue a long time. - * Better try to coalesce them right now - * to avoid future tcp_collapse_ofo_queue(), - * probably the most expensive function in tcp stack. - */ - if (skb->len <= skb_tailroom(skb1) && !tcp_hdr(skb)->fin) { - NET_INC_STATS_BH(sock_net(sk), - LINUX_MIB_TCPRCVCOALESCE); - BUG_ON(skb_copy_bits(skb, 0, - skb_put(skb1, skb->len), - skb->len)); - TCP_SKB_CB(skb1)->end_seq = end_seq; - TCP_SKB_CB(skb1)->ack_seq = TCP_SKB_CB(skb)->ack_seq; + if (tcp_try_coalesce(sk, skb1, skb) <= 0) { + __skb_queue_after(&tp->out_of_order_queue, skb1, skb); + } else { __kfree_skb(skb); skb = NULL; - } else { - __skb_queue_after(&tp->out_of_order_queue, skb1, skb); } if (!tp->rx_opt.num_sacks || @@ -4624,13 +4664,18 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) } if (eaten <= 0) { + struct sk_buff *tail; queue_and_out: if (eaten < 0 && tcp_try_rmem_schedule(sk, skb->truesize)) goto drop; - skb_set_owner_r(skb, sk); - __skb_queue_tail(&sk->sk_receive_queue, skb); + tail = skb_peek_tail(&sk->sk_receive_queue); + eaten = tail ? tcp_try_coalesce(sk, tail, skb) : -1; + if (eaten <= 0) { + skb_set_owner_r(skb, sk); + __skb_queue_tail(&sk->sk_receive_queue, skb); + } } tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; if (skb->len) |