There are some potential feefilter cleanups mentioned and motivated in comment https://github.com/bitcoin/bitcoin/pull/21509#issuecomment-805808485 . If you address the locking one, please be careful and make sure that `round()` is only called under a lock. See https://github.com/bitcoin/bitcoin/pull/21509#issuecomment-807992199

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* Bitcoin Core P2P design
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return;
        }
        if (pfrom.IsInboundConn() && addrMe.IsRoutable())
        {
            SeenLocal(addrMe);
        }
        
        
        if (pfrom.IsInboundConn()) PushNodeVersion(pfrom, GetAdjustedTime());
        
        const int greatest_common_version = std::min(nVersion, PROTOCOL_VERSION);
        pfrom.SetCommonVersion(greatest_common_version);
        pfrom.nVersion = nVersion;
        const CNetMsgMaker msg_maker(greatest_common_version);
        if (greatest_common_version >= WTXID_RELAY_VERSION) {
            m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::WTXIDRELAY));
        }
        
        if (greatest_common_version >= 70016) {
            
            
            
            
            m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::SENDADDRV2));
        }
        m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::VERACK));
        pfrom.nServices = nServices;
        pfrom.SetAddrLocal(addrMe);
        {
            LOCK(pfrom.cs_SubVer);