On 7/31/17 4:01 PM, Cong Wang wrote:
>>> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
>>> index 3a19ea28339f..37db087b6c97 100644
>>> --- a/net/ipv4/tcp_ipv4.c
>>> +++ b/net/ipv4/tcp_ipv4.c
>>> @@ -1855,7 +1855,7 @@ void inet_sk_rx_dst_set(struct sock *sk, const
>>> struct sk_buff *skb)
>>> {
>>> struct dst_entry *dst = skb_dst(skb);
>>>
>>> - if (dst && dst_hold_safe(dst)) {
>>> + if (0 && dst && dst_hold_safe(dst)) {
>>> sk->sk_rx_dst = dst;
>>> inet_sk(sk)->rx_dst_ifindex = skb->skb_iif;
>>> }
>>
>>
>> This removes the 200s stall (the test is IPv4/TCP based)
>
>
> Interesting. This means we have a kernel socket which holds
> the dst refcnt.
Right now there is no tracking that I am aware of for a dst cached on
the socket (outside of walking all sockets). I have been bitten by it
several times in trying to make various changes. It's basically a hidden
reference for the device.
