Commit 53240c20 authored by Ali Saidi's avatar Ali Saidi Committed by David S. Miller

tcp: Fix possible double-ack w/ user dma

From: Ali Saidi <saidi@engin.umich.edu>

When TCP receive copy offload is enabled it's possible that
tcp_rcv_established() will cause two acks to be sent for a single
packet. In the case that a tcp_dma_early_copy() is successful,
copied_early is set to true which causes tcp_cleanup_rbuf() to be
called early which can send an ack. Further along in
tcp_rcv_established(), __tcp_ack_snd_check() is called and will
schedule a delayed ACK. If no packets are processed before the delayed
ack timer expires the packet will be acked twice.
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b6c40d68
...@@ -4879,7 +4879,8 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb, ...@@ -4879,7 +4879,8 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
goto no_ack; goto no_ack;
} }
__tcp_ack_snd_check(sk, 0); if (!copied_early || tp->rcv_nxt != tp->rcv_wup)
__tcp_ack_snd_check(sk, 0);
no_ack: no_ack:
#ifdef CONFIG_NET_DMA #ifdef CONFIG_NET_DMA
if (copied_early) if (copied_early)
......
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