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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if (pfrom.m_tx_relay != nullptr) {
            LOCK(pfrom.m_tx_relay->cs_tx_inventory);
            pfrom.m_tx_relay->fSendMempool = true;
        }
        return;
    }
    if (msg_type == NetMsgType::PING) {
        if (pfrom.GetCommonVersion() > BIP0031_VERSION) {
            uint64_t nonce = 0;
            vRecv >> nonce;
            
            
            
            
            
            
            
            
            
            
            
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::PONG, nonce));
        }
        return;
    }
    if (msg_type == NetMsgType::PONG) {
        const auto ping_end = time_received;
        uint64_t nonce = 0;
        size_t nAvail = vRecv.in_avail();
        bool bPingFinished = false;