tcp: fix ooo_okay setting vs Small Queues (b2532eb9) · Commits · 戴 / test

TCP Small Queues (tcp_tsq_handler()) can hold one reference on sk->sk_wmem_alloc, preventing skb->ooo_okay being set. We should relax test done to set skb->ooo_okay to take care of this extra reference. Minimal truesize of skb containing one byte of payload is SKB_TRUESIZE(1) Without this fix, we have more chance locking flows into the wrong transmit queue. Signed-off-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/ipv4/tcp_output.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -914,9 +914,13 @@ static int tcp_transmit_skb(struct sock sk, struct sk_buff skb, int clone_it,
		tcp_ca_event(sk, CA_EVENT_TX_START);

		/* if no packet is in qdisc/device queue, then allow XPS to select
		* another queue.
		* another queue. We can be called from tcp_tsq_handler()
		* which holds one reference to sk_wmem_alloc.
		*
		* TODO: Ideally, in-flight pure ACK packets should not matter here.
		* One way to get this would be to set skb->truesize = 2 on them.
		*/
		skb->ooo_okay = sk_wmem_alloc_get(sk) == 0;
		skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1);

		skb_push(skb, tcp_header_size);
		skb_reset_transport_header(skb);

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