tcp: avoid retransmits of TCP packets hanging in host queues
In commit 0e280af0 ("tcp: introduce TCPSpuriousRtxHostQueues SNMP counter") we added a logic to detect when a packet was retransmitted while the prior clone was still in a qdisc or driver queue. We are now confident we can do better, and catch the problem before we fragment a TSO packet before retransmit, or in TLP path. This patch fully exploits the logic by simply canceling the spurious retransmit. Original packet is in a queue and will eventually leave the host. This helps to avoid network collapses when some events make the RTO estimations very wrong, particularly when dealing with huge number of sockets with synchronized blast. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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