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tcp: add coalescing attempt in tcp_ofo_queue()

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In order to make TCP more resilient in presence of reorders, we need
to allow coalescing to happen when skbs from out of order queue are
transferred into receive queue. LRO/GRO can be completely canceled
in some pathological cases, like per packet load balancing on aggregated
links.

I had to move tcp_try_coalesce() up in the file above tcp_ofo_queue()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2014-09-19 08:26:20 -07:00 committed by David S. Miller
parent 4cdf507d54
commit bd1e75abf4
1 changed files with 66 additions and 61 deletions
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127
net/ipv4/tcp_input.c
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@ -4061,67 +4061,6 @@ static void tcp_sack_remove(struct tcp_sock *tp)
tp->rx_opt.num_sacks = num_sacks;
}
/* This one checks to see if we can put data from the
* out_of_order queue into the receive_queue.
*/
static void tcp_ofo_queue(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
__u32 dsack_high = tp->rcv_nxt;
struct sk_buff *skb;
while ((skb = skb_peek(&tp->out_of_order_queue)) != NULL) {
if (after(TCP_SKB_CB(skb)->seq, tp->rcv_nxt))
break;
if (before(TCP_SKB_CB(skb)->seq, dsack_high)) {
__u32 dsack = dsack_high;
if (before(TCP_SKB_CB(skb)->end_seq, dsack_high))
dsack_high = TCP_SKB_CB(skb)->end_seq;
tcp_dsack_extend(sk, TCP_SKB_CB(skb)->seq, dsack);
}
if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) {
SOCK_DEBUG(sk, "ofo packet was already received\n");
__skb_unlink(skb, &tp->out_of_order_queue);
__kfree_skb(skb);
continue;
}
SOCK_DEBUG(sk, "ofo requeuing : rcv_next %X seq %X - %X\n",
tp->rcv_nxt, TCP_SKB_CB(skb)->seq,
TCP_SKB_CB(skb)->end_seq);
__skb_unlink(skb, &tp->out_of_order_queue);
__skb_queue_tail(&sk->sk_receive_queue, skb);
tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
tcp_fin(sk);
}
}
static bool tcp_prune_ofo_queue(struct sock *sk);
static int tcp_prune_queue(struct sock *sk);
static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb,
unsigned int size)
{
if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
!sk_rmem_schedule(sk, skb, size)) {
if (tcp_prune_queue(sk) < 0)
return -1;
if (!sk_rmem_schedule(sk, skb, size)) {
if (!tcp_prune_ofo_queue(sk))
return -1;
if (!sk_rmem_schedule(sk, skb, size))
return -1;
}
}
return 0;
}
/**
* tcp_try_coalesce - try to merge skb to prior one
* @sk: socket
@ -4160,6 +4099,72 @@ static bool tcp_try_coalesce(struct sock *sk,
return true;
}
/* This one checks to see if we can put data from the
* out_of_order queue into the receive_queue.
*/
static void tcp_ofo_queue(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
__u32 dsack_high = tp->rcv_nxt;
struct sk_buff *skb, *tail;
bool fragstolen, eaten;
while ((skb = skb_peek(&tp->out_of_order_queue)) != NULL) {
if (after(TCP_SKB_CB(skb)->seq, tp->rcv_nxt))
break;
if (before(TCP_SKB_CB(skb)->seq, dsack_high)) {
__u32 dsack = dsack_high;
if (before(TCP_SKB_CB(skb)->end_seq, dsack_high))
dsack_high = TCP_SKB_CB(skb)->end_seq;
tcp_dsack_extend(sk, TCP_SKB_CB(skb)->seq, dsack);
}
__skb_unlink(skb, &tp->out_of_order_queue);
if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) {
SOCK_DEBUG(sk, "ofo packet was already received\n");
__kfree_skb(skb);
continue;
}
SOCK_DEBUG(sk, "ofo requeuing : rcv_next %X seq %X - %X\n",
tp->rcv_nxt, TCP_SKB_CB(skb)->seq,
TCP_SKB_CB(skb)->end_seq);
tail = skb_peek_tail(&sk->sk_receive_queue);
eaten = tail && tcp_try_coalesce(sk, tail, skb, &fragstolen);
tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
if (!eaten)
__skb_queue_tail(&sk->sk_receive_queue, skb);
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
tcp_fin(sk);
if (eaten)
kfree_skb_partial(skb, fragstolen);
}
}
static bool tcp_prune_ofo_queue(struct sock *sk);
static int tcp_prune_queue(struct sock *sk);
static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb,
unsigned int size)
{
if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
!sk_rmem_schedule(sk, skb, size)) {
if (tcp_prune_queue(sk) < 0)
return -1;
if (!sk_rmem_schedule(sk, skb, size)) {
if (!tcp_prune_ofo_queue(sk))
return -1;
if (!sk_rmem_schedule(sk, skb, size))
return -1;
}
}
return 0;
}
static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);