Commit 76dfa608 authored May 15, 2015 by Eric Dumazet Committed by David S. Miller May 17, 2015

tcp: allow one skb to be received per socket under memory pressure



While testing tight tcp_mem settings, I found tcp sessions could be
stuck because we do not allow even one skb to be received on them.

By allowing one skb to be received, we introduce fairness and
eventuallu force memory hogs to release their allocation.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 8e4d980a

net/ipv4/tcp_input.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -4507,10 +4507,12 @@ static void tcp_data_queue(struct sock sk, struct sk_buff skb)

		if (eaten <= 0) {
		queue_and_out:
		if (eaten < 0 &&
		tcp_try_rmem_schedule(sk, skb, skb->truesize))
		if (eaten < 0) {
		if (skb_queue_len(&sk->sk_receive_queue) == 0)
		sk_forced_mem_schedule(sk, skb->truesize);
		else if (tcp_try_rmem_schedule(sk, skb, skb->truesize))
		goto drop;

		}
		eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen);
		}
		tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);

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