Commit b9f1f1ce authored Oct 16, 2017 by Eric Dumazet Committed by David S. Miller Oct 18, 2017

tcp: fix tcp_xmit_retransmit_queue() after rbtree introduction



I tried to hard avoiding a call to rb_first() (via tcp_rtx_queue_head)
in tcp_xmit_retransmit_queue(). But this was probably too bold.

Quoting Yuchung :

We might miss re-arming the RTO if tp->retransmit_skb_hint is not NULL.
This can happen when RACK marks the first packet lost again and resets
tp->retransmit_skb_hint for example (tcp_rack_mark_skb_lost())

Fixes: 75c119af ("tcp: implement rb-tree based retransmit queue")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent b082af73

net/ipv4/tcp_output.c

+3 −6

Original line number	Diff line number	Diff line
		@@ -2921,7 +2921,7 @@ int tcp_retransmit_skb(struct sock sk, struct sk_buff skb, int segs)
		void tcp_xmit_retransmit_queue(struct sock *sk)
		{
		const struct inet_connection_sock *icsk = inet_csk(sk);
		struct sk_buff skb, rtx_head = NULL, *hole = NULL;
		struct sk_buff skb, rtx_head, *hole = NULL;
		struct tcp_sock *tp = tcp_sk(sk);
		u32 max_segs;
		int mib_idx;
		@@ -2929,11 +2929,8 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
		if (!tp->packets_out)
		return;

		skb = tp->retransmit_skb_hint;
		if (!skb) {
		rtx_head = tcp_rtx_queue_head(sk);
		skb = rtx_head;
		}
		skb = tp->retransmit_skb_hint ?: rtx_head;
		max_segs = tcp_tso_segs(sk, tcp_current_mss(sk));
		skb_rbtree_walk_from(skb) {
		__u8 sacked;

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