Just saw https://reviews.freebsd.org/D46068. If this patch has not been committed, we can still further revise it, so that D46068 can be cleaner on function re-use.

I think the logic here can be split into two functions, such that the refined logic 1 on checking if we should send ACK can be re-used across multiple places.

logic 1:

bool
is_ack_unlimited(struct tcpcb *tp)
{
    /* focus on checking the epoch and
     * if should send ACK, return true; else return false
     */ 
}

logic 2:

void
tcp_send_challenge_ack(struct tcpcb *tp, struct tcphdr *th, struct mbuf *m)
{
    if (is_ack_unlimited(tp)) {.
       tcp_respond();
    ....
    }
}

In D46066#1050919, @cc wrote:

Just saw https://reviews.freebsd.org/D46068. If this patch has not been committed, we can still further revise it, so that D46068 can be cleaner on function re-use.

I think the logic here can be split into two functions, such that the refined logic 1 on checking if we should send ACK can be re-used across multiple places.

logic 1:

bool
is_ack_unlimited(struct tcpcb *tp)
{
    /* focus on checking the epoch and
     * if should send ACK, return true; else return false
     */ 
}

logic 2:

void
tcp_send_challenge_ack(struct tcpcb *tp, struct tcphdr *th, struct mbuf *m)
{
    if (is_ack_unlimited(tp)) {.
       tcp_respond();
    ....
    }
}

I don't get the point. Eventually, all places should use tcp_send_challenge_ack(), I think. But that is multiple commits away.

In D46066#1051183, @tuexen wrote:

In D46066#1050919, @cc wrote:

Just saw https://reviews.freebsd.org/D46068. If this patch has not been committed, we can still further revise it, so that D46068 can be cleaner on function re-use.

I think the logic here can be split into two functions, such that the refined logic 1 on checking if we should send ACK can be re-used across multiple places.

logic 1:

bool
is_ack_unlimited(struct tcpcb *tp)
{
    /* focus on checking the epoch and
     * if should send ACK, return true; else return false
     */ 
}

logic 2:

void
tcp_send_challenge_ack(struct tcpcb *tp, struct tcphdr *th, struct mbuf *m)
{
    if (is_ack_unlimited(tp)) {.
       tcp_respond();
    ....
    }
}

I don't get the point. Eventually, all places should use tcp_send_challenge_ack(), I think. But that is multiple commits away.

For example, ctf_ack_war_checks() can be simply refined as this:

ctf_ack_war_checks()
{
    if (is_ack_unlimited(tp)) {
        tp->t_flags |= TF_ACKNOW;
    } else {
        tp->t_flags &= ~TF_ACKNOW;
    }
}