Function in_pcboutput_txrtlmt

freebsd/netinet/in_pcb.c:3619–3660

* This function should be called when the INP_RATE_LIMIT_CHANGED flag * is set in the fast path and will attach/detach/modify the TX rate * limit send tag based on the socket's so_max_pacing_rate value. */

 * limit send tag based on the socket's so_max_pacing_rate value.
 */
void
in_pcboutput_txrtlmt(struct inpcb *inp, struct ifnet *ifp, struct mbuf *mb)
{
	struct socket *socket;
	uint32_t max_pacing_rate;
	bool did_upgrade;
	int error;

	if (inp == NULL)
		return;

	socket = inp->inp_socket;
	if (socket == NULL)
		return;

	if (!INP_WLOCKED(inp)) {
		/*
		 * NOTE: If the write locking fails, we need to bail
		 * out and use the non-ratelimited ring for the
		 * transmit until there is a new chance to get the
		 * write lock.
		 */
		if (!INP_TRY_UPGRADE(inp))
			return;
		did_upgrade = 1;
	} else {
		did_upgrade = 0;
	}

	/*
	 * NOTE: The so_max_pacing_rate value is read unlocked,
	 * because atomic updates are not required since the variable
	 * is checked at every mbuf we send. It is assumed that the
	 * variable read itself will be atomic.
	 */
	max_pacing_rate = socket->so_max_pacing_rate;

	error = in_pcboutput_txrtlmt_locked(inp, ifp, mb, max_pacing_rate);

	if (did_upgrade)
		INP_DOWNGRADE(inp);
}

/*
 * Track route changes for TX rate limiting.