Commit 2594a2a9 authored Sep 09, 2016 by Eric Dumazet Committed by David S. Miller Sep 10, 2016

tcp: better use ooo_last_skb in tcp_data_queue_ofo()



Willem noticed that we could avoid an rbtree lookup if the
the attempt to coalesce incoming skb to the last skb failed
for some reason.

Since most ooo additions are at the tail, this is definitely
worth adding a test and fast path.

Suggested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yaogong Wang <wygivan@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent ed227099

net/ipv4/tcp_input.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -4461,6 +4461,12 @@ coalesce_done:
		skb = NULL;
		goto add_sack;
		}
		/* Can avoid an rbtree lookup if we are adding skb after ooo_last_skb */
		if (!before(seq, TCP_SKB_CB(tp->ooo_last_skb)->end_seq)) {
		parent = &tp->ooo_last_skb->rbnode;
		p = &parent->rb_right;
		goto insert;
		}

		/* Find place to insert this segment. Handle overlaps on the way. */
		parent = NULL;
		@@ -4503,7 +4509,7 @@ coalesce_done:
		}
		p = &parent->rb_right;
		}

		insert:
		/* Insert segment into RB tree. */
		rb_link_node(&skb->rbnode, parent, p);
		rb_insert_color(&skb->rbnode, &tp->out_of_order_queue);

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