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Liu Yu authored
commit b9f47a3a (tcp_cubic: limit delayed_ack ratio to prevent divide error) try to prevent divide error, but there is still a little chance that delayed_ack can reach zero. In case the param cnt get negative value, then ratio+cnt would overflow and may happen to be zero. As a result, min(ratio, ACK_RATIO_LIMIT) will calculate to be zero. In some old kernels, such as 2.6.32, there is a bug that would pass negative param, which then ultimately leads to this divide error. commit 5b35e1e6 (tcp: fix tcp_trim_head() to adjust segment count with skb MSS) fixed the negative param issue. However, it's safe that we fix the range of delayed_ack as well, to make sure we do not hit a divide by zero. CC: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by:
Liu Yu <allanyuliu@tencent.com> Signed-off-by:
Eric Dumazet <edumazet@google.com> Acked-by:
Neal Cardwell <ncardwell@google.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
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