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Commit e86b2919 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: introduce tcp_data_queue_ofo 



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: default avatarEric 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: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent de128804

net/ipv4/tcp_input.c

+115 −99
Original line number Diff line number Diff line
@@ -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);
@@ -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,