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tcp: introduce tcp_data_queue_ofo
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Split tcp_data_queue() in two parts for better readability.

tcp_data_queue_ofo() is responsible for queueing incoming skb into out
of order queue.

Change code layout so that the skb_set_owner_r() is performed only if
skb is not dropped.

This is a preliminary patch before "reduce out_of_order memory use"
following patch.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: H.K. Jerry Chu <hkchu@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Eric Dumazet authored and David S. Miller committed Mar 19, 2012
1 parent de12880 commit e86b291
Showing 1 changed file with 115 additions and 99 deletions.
214 changes: 115 additions & 99 deletions net/ipv4/tcp_input.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4446,6 +4446,120 @@ static inline int tcp_try_rmem_schedule(struct sock *sk, unsigned int size)
return 0;
}

static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb1;
u32 seq, end_seq;

TCP_ECN_check_ce(tp, skb);

if (tcp_try_rmem_schedule(sk, skb->truesize)) {
/* TODO: should increment a counter */
__kfree_skb(skb);
return;
}

/* Disable header prediction. */
tp->pred_flags = 0;
inet_csk_schedule_ack(sk);

SOCK_DEBUG(sk, "out of order segment: rcv_next %X seq %X - %X\n",
tp->rcv_nxt, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq);

skb1 = skb_peek_tail(&tp->out_of_order_queue);
if (!skb1) {
/* Initial out of order segment, build 1 SACK. */
if (tcp_is_sack(tp)) {
tp->rx_opt.num_sacks = 1;
tp->selective_acks[0].start_seq = TCP_SKB_CB(skb)->seq;
tp->selective_acks[0].end_seq =
TCP_SKB_CB(skb)->end_seq;
}
__skb_queue_head(&tp->out_of_order_queue, skb);
goto end;
}

seq = TCP_SKB_CB(skb)->seq;
end_seq = TCP_SKB_CB(skb)->end_seq;

if (seq == TCP_SKB_CB(skb1)->end_seq) {
__skb_queue_after(&tp->out_of_order_queue, skb1, skb);

if (!tp->rx_opt.num_sacks ||
tp->selective_acks[0].end_seq != seq)
goto add_sack;

/* Common case: data arrive in order after hole. */
tp->selective_acks[0].end_seq = end_seq;
goto end;
}

/* Find place to insert this segment. */
while (1) {
if (!after(TCP_SKB_CB(skb1)->seq, seq))
break;
if (skb_queue_is_first(&tp->out_of_order_queue, skb1)) {
skb1 = NULL;
break;
}
skb1 = skb_queue_prev(&tp->out_of_order_queue, skb1);
}

/* Do skb overlap to previous one? */
if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) {
if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
/* All the bits are present. Drop. */
__kfree_skb(skb);
skb = NULL;
tcp_dsack_set(sk, seq, end_seq);
goto add_sack;
}
if (after(seq, TCP_SKB_CB(skb1)->seq)) {
/* Partial overlap. */
tcp_dsack_set(sk, seq,
TCP_SKB_CB(skb1)->end_seq);
} else {
if (skb_queue_is_first(&tp->out_of_order_queue,
skb1))
skb1 = NULL;
else
skb1 = skb_queue_prev(
&tp->out_of_order_queue,
skb1);
}
}
if (!skb1)
__skb_queue_head(&tp->out_of_order_queue, skb);
else
__skb_queue_after(&tp->out_of_order_queue, skb1, skb);

/* And clean segments covered by new one as whole. */
while (!skb_queue_is_last(&tp->out_of_order_queue, skb)) {
skb1 = skb_queue_next(&tp->out_of_order_queue, skb);

if (!after(end_seq, TCP_SKB_CB(skb1)->seq))
break;
if (before(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq,
end_seq);
break;
}
__skb_unlink(skb1, &tp->out_of_order_queue);
tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq,
TCP_SKB_CB(skb1)->end_seq);
__kfree_skb(skb1);
}

add_sack:
if (tcp_is_sack(tp))
tcp_sack_new_ofo_skb(sk, seq, end_seq);
end:
if (skb)
skb_set_owner_r(skb, sk);
}


static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
{
const struct tcphdr *th = tcp_hdr(skb);
Expand Down Expand Up @@ -4561,105 +4675,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
goto queue_and_out;
}

TCP_ECN_check_ce(tp, skb);

if (tcp_try_rmem_schedule(sk, skb->truesize))
goto drop;

/* Disable header prediction. */
tp->pred_flags = 0;
inet_csk_schedule_ack(sk);

SOCK_DEBUG(sk, "out of order segment: rcv_next %X seq %X - %X\n",
tp->rcv_nxt, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq);

skb_set_owner_r(skb, sk);

if (!skb_peek(&tp->out_of_order_queue)) {
/* Initial out of order segment, build 1 SACK. */
if (tcp_is_sack(tp)) {
tp->rx_opt.num_sacks = 1;
tp->selective_acks[0].start_seq = TCP_SKB_CB(skb)->seq;
tp->selective_acks[0].end_seq =
TCP_SKB_CB(skb)->end_seq;
}
__skb_queue_head(&tp->out_of_order_queue, skb);
} else {
struct sk_buff *skb1 = skb_peek_tail(&tp->out_of_order_queue);
u32 seq = TCP_SKB_CB(skb)->seq;
u32 end_seq = TCP_SKB_CB(skb)->end_seq;

if (seq == TCP_SKB_CB(skb1)->end_seq) {
__skb_queue_after(&tp->out_of_order_queue, skb1, skb);

if (!tp->rx_opt.num_sacks ||
tp->selective_acks[0].end_seq != seq)
goto add_sack;

/* Common case: data arrive in order after hole. */
tp->selective_acks[0].end_seq = end_seq;
return;
}

/* Find place to insert this segment. */
while (1) {
if (!after(TCP_SKB_CB(skb1)->seq, seq))
break;
if (skb_queue_is_first(&tp->out_of_order_queue, skb1)) {
skb1 = NULL;
break;
}
skb1 = skb_queue_prev(&tp->out_of_order_queue, skb1);
}

/* Do skb overlap to previous one? */
if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) {
if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
/* All the bits are present. Drop. */
__kfree_skb(skb);
tcp_dsack_set(sk, seq, end_seq);
goto add_sack;
}
if (after(seq, TCP_SKB_CB(skb1)->seq)) {
/* Partial overlap. */
tcp_dsack_set(sk, seq,
TCP_SKB_CB(skb1)->end_seq);
} else {
if (skb_queue_is_first(&tp->out_of_order_queue,
skb1))
skb1 = NULL;
else
skb1 = skb_queue_prev(
&tp->out_of_order_queue,
skb1);
}
}
if (!skb1)
__skb_queue_head(&tp->out_of_order_queue, skb);
else
__skb_queue_after(&tp->out_of_order_queue, skb1, skb);

/* And clean segments covered by new one as whole. */
while (!skb_queue_is_last(&tp->out_of_order_queue, skb)) {
skb1 = skb_queue_next(&tp->out_of_order_queue, skb);

if (!after(end_seq, TCP_SKB_CB(skb1)->seq))
break;
if (before(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq,
end_seq);
break;
}
__skb_unlink(skb1, &tp->out_of_order_queue);
tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq,
TCP_SKB_CB(skb1)->end_seq);
__kfree_skb(skb1);
}

add_sack:
if (tcp_is_sack(tp))
tcp_sack_new_ofo_skb(sk, seq, end_seq);
}
tcp_data_queue_ofo(sk, skb);
}

static struct sk_buff *tcp_collapse_one(struct sock *sk, struct sk_buff *skb,
Expand Down

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