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Make ifq and ifiq interface MP safe.

Rename ifq_set_maxlen() to ifq_init_maxlen().  This function neither
uses WRITE_ONCE() nor a mutex and is called before the ifq mutex
is initialized.  The new name expresses that it should be used only
during interface attach when there is no concurrency.

Protect ifq_len(), ifq_empty(), ifiq_len(), and ifiq_empty() with
READ_ONCE().  They can be used without lock as they only read a
single integer.

OK dlg@

/*	$OpenBSD: ifq.c,v 1.53 2023/11/10 15:51:24 bluhm Exp $ */

/*
 * Copyright (c) 2015 David Gwynne <dlg@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "bpfilter.h"
#include "kstat.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/socket.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_var.h>

#if NBPFILTER > 0
#include <net/bpf.h>
#endif

#if NKSTAT > 0
#include <sys/kstat.h>
#endif

/*
 * priq glue
 */
unsigned int	 priq_idx(unsigned int, const struct mbuf *);
struct mbuf	*priq_enq(struct ifqueue *, struct mbuf *);
struct mbuf	*priq_deq_begin(struct ifqueue *, void **);
void		 priq_deq_commit(struct ifqueue *, struct mbuf *, void *);
void		 priq_purge(struct ifqueue *, struct mbuf_list *);

void		*priq_alloc(unsigned int, void *);
void		 priq_free(unsigned int, void *);

const struct ifq_ops priq_ops = {
	priq_idx,
	priq_enq,
	priq_deq_begin,
	priq_deq_commit,
	priq_purge,
	priq_alloc,
	priq_free,
};

const struct ifq_ops * const ifq_priq_ops = &priq_ops;

/*
 * priq internal structures
 */

struct priq {
	struct mbuf_list	 pq_lists[IFQ_NQUEUES];
};

/*
 * ifqueue serialiser
 */

void	ifq_start_task(void *);
void	ifq_restart_task(void *);
void	ifq_barrier_task(void *);
void	ifq_bundle_task(void *);

static inline void
ifq_run_start(struct ifqueue *ifq)
{
	ifq_serialize(ifq, &ifq->ifq_start);
}

void
ifq_serialize(struct ifqueue *ifq, struct task *t)
{
	struct task work;

	if (ISSET(t->t_flags, TASK_ONQUEUE))
		return;

	mtx_enter(&ifq->ifq_task_mtx);
	if (!ISSET(t->t_flags, TASK_ONQUEUE)) {
		SET(t->t_flags, TASK_ONQUEUE);
		TAILQ_INSERT_TAIL(&ifq->ifq_task_list, t, t_entry);
	}

	if (ifq->ifq_serializer == NULL) {
		ifq->ifq_serializer = curcpu();

		while ((t = TAILQ_FIRST(&ifq->ifq_task_list)) != NULL) {
			TAILQ_REMOVE(&ifq->ifq_task_list, t, t_entry);
			CLR(t->t_flags, TASK_ONQUEUE);
			work = *t; /* copy to caller to avoid races */

			mtx_leave(&ifq->ifq_task_mtx);

			(*work.t_func)(work.t_arg);

			mtx_enter(&ifq->ifq_task_mtx);
		}

		ifq->ifq_serializer = NULL;
	}
	mtx_leave(&ifq->ifq_task_mtx);
}

int
ifq_is_serialized(struct ifqueue *ifq)
{
	return (ifq->ifq_serializer == curcpu());
}

void
ifq_start(struct ifqueue *ifq)
{
	if (ifq_len(ifq) >= min(ifq->ifq_if->if_txmit, ifq->ifq_maxlen)) {
		task_del(ifq->ifq_softnet, &ifq->ifq_bundle);
		ifq_run_start(ifq);
	} else
		task_add(ifq->ifq_softnet, &ifq->ifq_bundle);
}

void
ifq_start_task(void *p)
{
	struct ifqueue *ifq = p;
	struct ifnet *ifp = ifq->ifq_if;

	if (!ISSET(ifp->if_flags, IFF_RUNNING) ||
	    ifq_empty(ifq) || ifq_is_oactive(ifq))
		return;

	ifp->if_qstart(ifq);
}

void
ifq_set_oactive(struct ifqueue *ifq)
{
	if (ifq->ifq_oactive)
		return;

	mtx_enter(&ifq->ifq_mtx);
	if (!ifq->ifq_oactive) {
		ifq->ifq_oactive = 1;
		ifq->ifq_oactives++;
	}
	mtx_leave(&ifq->ifq_mtx);
}

void
ifq_restart_task(void *p)
{
	struct ifqueue *ifq = p;
	struct ifnet *ifp = ifq->ifq_if;

	ifq_clr_oactive(ifq);
	ifp->if_qstart(ifq);
}

void
ifq_bundle_task(void *p)
{
	struct ifqueue *ifq = p;

	ifq_run_start(ifq);
}

void
ifq_barrier(struct ifqueue *ifq)
{
	struct cond c = COND_INITIALIZER();
	struct task t = TASK_INITIALIZER(ifq_barrier_task, &c);

	task_del(ifq->ifq_softnet, &ifq->ifq_bundle);

	if (ifq->ifq_serializer == NULL)
		return;

	ifq_serialize(ifq, &t);

	cond_wait(&c, "ifqbar");
}

void
ifq_barrier_task(void *p)
{
	struct cond *c = p;

	cond_signal(c);
}

/*
 * ifqueue mbuf queue API
 */

#if NKSTAT > 0
struct ifq_kstat_data {
	struct kstat_kv kd_packets;
	struct kstat_kv kd_bytes;
	struct kstat_kv kd_qdrops;
	struct kstat_kv kd_errors;
	struct kstat_kv kd_qlen;
	struct kstat_kv kd_maxqlen;
	struct kstat_kv kd_oactive;
	struct kstat_kv kd_oactives;
};

static const struct ifq_kstat_data ifq_kstat_tpl = {
	KSTAT_KV_UNIT_INITIALIZER("packets",
	    KSTAT_KV_T_COUNTER64, KSTAT_KV_U_PACKETS),
	KSTAT_KV_UNIT_INITIALIZER("bytes",
	    KSTAT_KV_T_COUNTER64, KSTAT_KV_U_BYTES),
	KSTAT_KV_UNIT_INITIALIZER("qdrops",
	    KSTAT_KV_T_COUNTER64, KSTAT_KV_U_PACKETS),
	KSTAT_KV_UNIT_INITIALIZER("errors",
	    KSTAT_KV_T_COUNTER64, KSTAT_KV_U_PACKETS),
	KSTAT_KV_UNIT_INITIALIZER("qlen",
	    KSTAT_KV_T_UINT32, KSTAT_KV_U_PACKETS),
	KSTAT_KV_UNIT_INITIALIZER("maxqlen",
	    KSTAT_KV_T_UINT32, KSTAT_KV_U_PACKETS),
	KSTAT_KV_INITIALIZER("oactive", KSTAT_KV_T_BOOL),
	KSTAT_KV_INITIALIZER("oactives", KSTAT_KV_T_COUNTER32),
};

int
ifq_kstat_copy(struct kstat *ks, void *dst)
{
	struct ifqueue *ifq = ks->ks_softc;
	struct ifq_kstat_data *kd = dst;

	*kd = ifq_kstat_tpl;
	kstat_kv_u64(&kd->kd_packets) = ifq->ifq_packets;
	kstat_kv_u64(&kd->kd_bytes) = ifq->ifq_bytes;
	kstat_kv_u64(&kd->kd_qdrops) = ifq->ifq_qdrops;
	kstat_kv_u64(&kd->kd_errors) = ifq->ifq_errors;
	kstat_kv_u32(&kd->kd_qlen) = ifq->ifq_len;
	kstat_kv_u32(&kd->kd_maxqlen) = ifq->ifq_maxlen;
	kstat_kv_bool(&kd->kd_oactive) = ifq->ifq_oactive;
	kstat_kv_u32(&kd->kd_oactives) = ifq->ifq_oactives;

	return (0);
}
#endif

void
ifq_init(struct ifqueue *ifq, struct ifnet *ifp, unsigned int idx)
{
	ifq->ifq_if = ifp;
	ifq->ifq_softnet = net_tq(idx);
	ifq->ifq_softc = NULL;

	mtx_init(&ifq->ifq_mtx, IPL_NET);

	/* default to priq */
	ifq->ifq_ops = &priq_ops;
	ifq->ifq_q = priq_ops.ifqop_alloc(idx, NULL);

	ml_init(&ifq->ifq_free);
	ifq->ifq_len = 0;

	ifq->ifq_packets = 0;
	ifq->ifq_bytes = 0;
	ifq->ifq_qdrops = 0;
	ifq->ifq_errors = 0;
	ifq->ifq_mcasts = 0;

	mtx_init(&ifq->ifq_task_mtx, IPL_NET);
	TAILQ_INIT(&ifq->ifq_task_list);
	ifq->ifq_serializer = NULL;
	task_set(&ifq->ifq_bundle, ifq_bundle_task, ifq);

	task_set(&ifq->ifq_start, ifq_start_task, ifq);
	task_set(&ifq->ifq_restart, ifq_restart_task, ifq);

	if (ifq->ifq_maxlen == 0)
		ifq_init_maxlen(ifq, IFQ_MAXLEN);

	ifq->ifq_idx = idx;

#if NKSTAT > 0
	/* XXX xname vs driver name and unit */
	ifq->ifq_kstat = kstat_create(ifp->if_xname, 0,
	    "txq", ifq->ifq_idx, KSTAT_T_KV, 0);
	KASSERT(ifq->ifq_kstat != NULL);
	kstat_set_mutex(ifq->ifq_kstat, &ifq->ifq_mtx);
	ifq->ifq_kstat->ks_softc = ifq;
	ifq->ifq_kstat->ks_datalen = sizeof(ifq_kstat_tpl);
	ifq->ifq_kstat->ks_copy = ifq_kstat_copy;
	kstat_install(ifq->ifq_kstat);
#endif
}

void
ifq_attach(struct ifqueue *ifq, const struct ifq_ops *newops, void *opsarg)
{
	struct mbuf_list ml = MBUF_LIST_INITIALIZER();
	struct mbuf_list free_ml = MBUF_LIST_INITIALIZER();
	struct mbuf *m;
	const struct ifq_ops *oldops;
	void *newq, *oldq;

	newq = newops->ifqop_alloc(ifq->ifq_idx, opsarg);

	mtx_enter(&ifq->ifq_mtx);
	ifq->ifq_ops->ifqop_purge(ifq, &ml);
	ifq->ifq_len = 0;

	oldops = ifq->ifq_ops;
	oldq = ifq->ifq_q;

	ifq->ifq_ops = newops;
	ifq->ifq_q = newq;

	while ((m = ml_dequeue(&ml)) != NULL) {
		m = ifq->ifq_ops->ifqop_enq(ifq, m);
		if (m != NULL) {
			ifq->ifq_qdrops++;
			ml_enqueue(&free_ml, m);
		} else
			ifq->ifq_len++;
	}
	mtx_leave(&ifq->ifq_mtx);

	oldops->ifqop_free(ifq->ifq_idx, oldq);

	ml_purge(&free_ml);
}

void
ifq_destroy(struct ifqueue *ifq)
{
	struct mbuf_list ml = MBUF_LIST_INITIALIZER();

#if NKSTAT > 0
	kstat_destroy(ifq->ifq_kstat);
#endif

	NET_ASSERT_UNLOCKED();
	if (!task_del(ifq->ifq_softnet, &ifq->ifq_bundle))
		taskq_barrier(ifq->ifq_softnet);

	/* don't need to lock because this is the last use of the ifq */

	ifq->ifq_ops->ifqop_purge(ifq, &ml);
	ifq->ifq_ops->ifqop_free(ifq->ifq_idx, ifq->ifq_q);

	ml_purge(&ml);
}

void
ifq_add_data(struct ifqueue *ifq, struct if_data *data)
{
	mtx_enter(&ifq->ifq_mtx);
	data->ifi_opackets += ifq->ifq_packets;
	data->ifi_obytes += ifq->ifq_bytes;
	data->ifi_oqdrops += ifq->ifq_qdrops;
	data->ifi_omcasts += ifq->ifq_mcasts;
	/* ifp->if_data.ifi_oerrors */
	mtx_leave(&ifq->ifq_mtx);
}

int
ifq_enqueue(struct ifqueue *ifq, struct mbuf *m)
{
	struct mbuf *dm;

	mtx_enter(&ifq->ifq_mtx);
	dm = ifq->ifq_ops->ifqop_enq(ifq, m);
	if (dm != m) {
		ifq->ifq_packets++;
		ifq->ifq_bytes += m->m_pkthdr.len;
		if (ISSET(m->m_flags, M_MCAST))
			ifq->ifq_mcasts++;
	}

	if (dm == NULL)
		ifq->ifq_len++;
	else
		ifq->ifq_qdrops++;
	mtx_leave(&ifq->ifq_mtx);

	if (dm != NULL)
		m_freem(dm);

	return (dm == m ? ENOBUFS : 0);
}

static inline void
ifq_deq_enter(struct ifqueue *ifq)
{
	mtx_enter(&ifq->ifq_mtx);
}

static inline void
ifq_deq_leave(struct ifqueue *ifq)
{
	struct mbuf_list ml;

	ml = ifq->ifq_free;
	ml_init(&ifq->ifq_free);

	mtx_leave(&ifq->ifq_mtx);

	if (!ml_empty(&ml))
		ml_purge(&ml);
}

struct mbuf *
ifq_deq_begin(struct ifqueue *ifq)
{
	struct mbuf *m = NULL;
	void *cookie;

	ifq_deq_enter(ifq);
	if (ifq->ifq_len == 0 ||
	    (m = ifq->ifq_ops->ifqop_deq_begin(ifq, &cookie)) == NULL) {
		ifq_deq_leave(ifq);
		return (NULL);
	}

	m->m_pkthdr.ph_cookie = cookie;

	return (m);
}

void
ifq_deq_commit(struct ifqueue *ifq, struct mbuf *m)
{
	void *cookie;

	KASSERT(m != NULL);
	cookie = m->m_pkthdr.ph_cookie;

	ifq->ifq_ops->ifqop_deq_commit(ifq, m, cookie);
	ifq->ifq_len--;
	ifq_deq_leave(ifq);
}

void
ifq_deq_rollback(struct ifqueue *ifq, struct mbuf *m)
{
	KASSERT(m != NULL);

	ifq_deq_leave(ifq);
}

struct mbuf *
ifq_dequeue(struct ifqueue *ifq)
{
	struct mbuf *m;

	m = ifq_deq_begin(ifq);
	if (m == NULL)
		return (NULL);

	ifq_deq_commit(ifq, m);

	return (m);
}

int
ifq_deq_sleep(struct ifqueue *ifq, struct mbuf **mp, int nbio, int priority,
    const char *wmesg, volatile unsigned int *sleeping,
    volatile unsigned int *alive)
{
	struct mbuf *m;
	void *cookie;
	int error = 0;

	ifq_deq_enter(ifq);
	if (ifq->ifq_len == 0 && nbio)
		error = EWOULDBLOCK;
	else {
		for (;;) {
			m = ifq->ifq_ops->ifqop_deq_begin(ifq, &cookie);
			if (m != NULL) {
				ifq->ifq_ops->ifqop_deq_commit(ifq, m, cookie);
				ifq->ifq_len--;
				*mp = m;
				break;
			}

			(*sleeping)++;
			error = msleep_nsec(ifq, &ifq->ifq_mtx,
			    priority, wmesg, INFSLP);
			(*sleeping)--;
			if (error != 0)
				break;
			if (!(*alive)) {
				error = EIO;
				break;
			}
		}
	}
	ifq_deq_leave(ifq);

	return (error);
}

int
ifq_hdatalen(struct ifqueue *ifq)
{
	struct mbuf *m;
	int len = 0;

	if (ifq_empty(ifq))
		return (0);

	m = ifq_deq_begin(ifq);
	if (m != NULL) {
		len = m->m_pkthdr.len;
		ifq_deq_rollback(ifq, m);
	}

	return (len);
}

void
ifq_init_maxlen(struct ifqueue *ifq, unsigned int maxlen)
{
	/* this is not MP safe, use only during attach */
	ifq->ifq_maxlen = maxlen;
}

unsigned int
ifq_purge(struct ifqueue *ifq)
{
	struct mbuf_list ml = MBUF_LIST_INITIALIZER();
	unsigned int rv;

	mtx_enter(&ifq->ifq_mtx);
	ifq->ifq_ops->ifqop_purge(ifq, &ml);
	rv = ifq->ifq_len;
	ifq->ifq_len = 0;
	ifq->ifq_qdrops += rv;
	mtx_leave(&ifq->ifq_mtx);

	KASSERT(rv == ml_len(&ml));

	ml_purge(&ml);

	return (rv);
}

void *
ifq_q_enter(struct ifqueue *ifq, const struct ifq_ops *ops)
{
	mtx_enter(&ifq->ifq_mtx);
	if (ifq->ifq_ops == ops)
		return (ifq->ifq_q);

	mtx_leave(&ifq->ifq_mtx);

	return (NULL);
}

void
ifq_q_leave(struct ifqueue *ifq, void *q)
{
	KASSERT(q == ifq->ifq_q);
	mtx_leave(&ifq->ifq_mtx);
}

void
ifq_mfreem(struct ifqueue *ifq, struct mbuf *m)
{
	MUTEX_ASSERT_LOCKED(&ifq->ifq_mtx);

	ifq->ifq_len--;
	ifq->ifq_qdrops++;
	ml_enqueue(&ifq->ifq_free, m);
}

void
ifq_mfreeml(struct ifqueue *ifq, struct mbuf_list *ml)
{
	MUTEX_ASSERT_LOCKED(&ifq->ifq_mtx);

	ifq->ifq_len -= ml_len(ml);
	ifq->ifq_qdrops += ml_len(ml);
	ml_enlist(&ifq->ifq_free, ml);
}

/*
 * ifiq
 */

#if NKSTAT > 0
struct ifiq_kstat_data {
	struct kstat_kv kd_packets;
	struct kstat_kv kd_bytes;
	struct kstat_kv kd_fdrops;
	struct kstat_kv kd_qdrops;
	struct kstat_kv kd_errors;
	struct kstat_kv kd_qlen;

	struct kstat_kv kd_enqueues;
	struct kstat_kv kd_dequeues;
};

static const struct ifiq_kstat_data ifiq_kstat_tpl = {
	KSTAT_KV_UNIT_INITIALIZER("packets",
	    KSTAT_KV_T_COUNTER64, KSTAT_KV_U_PACKETS),
	KSTAT_KV_UNIT_INITIALIZER("bytes",
	    KSTAT_KV_T_COUNTER64, KSTAT_KV_U_BYTES),
	KSTAT_KV_UNIT_INITIALIZER("fdrops",
	    KSTAT_KV_T_COUNTER64, KSTAT_KV_U_PACKETS),
	KSTAT_KV_UNIT_INITIALIZER("qdrops",
	    KSTAT_KV_T_COUNTER64, KSTAT_KV_U_PACKETS),
	KSTAT_KV_UNIT_INITIALIZER("errors",
	    KSTAT_KV_T_COUNTER64, KSTAT_KV_U_PACKETS),
	KSTAT_KV_UNIT_INITIALIZER("qlen",
	    KSTAT_KV_T_UINT32, KSTAT_KV_U_PACKETS),

	KSTAT_KV_INITIALIZER("enqueues",
	    KSTAT_KV_T_COUNTER64),
	KSTAT_KV_INITIALIZER("dequeues",
	    KSTAT_KV_T_COUNTER64),
};

int
ifiq_kstat_copy(struct kstat *ks, void *dst)
{
	struct ifiqueue *ifiq = ks->ks_softc;
	struct ifiq_kstat_data *kd = dst;

	*kd = ifiq_kstat_tpl;
	kstat_kv_u64(&kd->kd_packets) = ifiq->ifiq_packets;
	kstat_kv_u64(&kd->kd_bytes) = ifiq->ifiq_bytes;
	kstat_kv_u64(&kd->kd_fdrops) = ifiq->ifiq_fdrops;
	kstat_kv_u64(&kd->kd_qdrops) = ifiq->ifiq_qdrops;
	kstat_kv_u64(&kd->kd_errors) = ifiq->ifiq_errors;
	kstat_kv_u32(&kd->kd_qlen) = ml_len(&ifiq->ifiq_ml);

	kstat_kv_u64(&kd->kd_enqueues) = ifiq->ifiq_enqueues;
	kstat_kv_u64(&kd->kd_dequeues) = ifiq->ifiq_dequeues;

	return (0);
}
#endif

static void	ifiq_process(void *);

void
ifiq_init(struct ifiqueue *ifiq, struct ifnet *ifp, unsigned int idx)
{
	ifiq->ifiq_if = ifp;
	ifiq->ifiq_softnet = net_tq(idx);
	ifiq->ifiq_softc = NULL;

	mtx_init(&ifiq->ifiq_mtx, IPL_NET);
	ml_init(&ifiq->ifiq_ml);
	task_set(&ifiq->ifiq_task, ifiq_process, ifiq);
	ifiq->ifiq_pressure = 0;

	ifiq->ifiq_packets = 0;
	ifiq->ifiq_bytes = 0;
	ifiq->ifiq_fdrops = 0;
	ifiq->ifiq_qdrops = 0;
	ifiq->ifiq_errors = 0;

	ifiq->ifiq_idx = idx;

#if NKSTAT > 0
	/* XXX xname vs driver name and unit */
	ifiq->ifiq_kstat = kstat_create(ifp->if_xname, 0,
	    "rxq", ifiq->ifiq_idx, KSTAT_T_KV, 0);
	KASSERT(ifiq->ifiq_kstat != NULL);
	kstat_set_mutex(ifiq->ifiq_kstat, &ifiq->ifiq_mtx);
	ifiq->ifiq_kstat->ks_softc = ifiq;
	ifiq->ifiq_kstat->ks_datalen = sizeof(ifiq_kstat_tpl);
	ifiq->ifiq_kstat->ks_copy = ifiq_kstat_copy;
	kstat_install(ifiq->ifiq_kstat);
#endif
}

void
ifiq_destroy(struct ifiqueue *ifiq)
{
#if NKSTAT > 0
	kstat_destroy(ifiq->ifiq_kstat);
#endif

	NET_ASSERT_UNLOCKED();
	if (!task_del(ifiq->ifiq_softnet, &ifiq->ifiq_task))
		taskq_barrier(ifiq->ifiq_softnet);

	/* don't need to lock because this is the last use of the ifiq */
	ml_purge(&ifiq->ifiq_ml);
}

unsigned int ifiq_maxlen_drop = 2048 * 5;
unsigned int ifiq_maxlen_return = 2048 * 3;

int
ifiq_input(struct ifiqueue *ifiq, struct mbuf_list *ml)
{
	struct ifnet *ifp = ifiq->ifiq_if;
	struct mbuf *m;
	uint64_t packets;
	uint64_t bytes = 0;
	uint64_t fdrops = 0;
	unsigned int len;
#if NBPFILTER > 0
	caddr_t if_bpf;
#endif

	if (ml_empty(ml))
		return (0);

	MBUF_LIST_FOREACH(ml, m) {
		m->m_pkthdr.ph_ifidx = ifp->if_index;
		m->m_pkthdr.ph_rtableid = ifp->if_rdomain;
		bytes += m->m_pkthdr.len;
	}
	packets = ml_len(ml);

#if NBPFILTER > 0
	if_bpf = ifp->if_bpf;
	if (if_bpf) {
		struct mbuf_list ml0 = *ml;

		ml_init(ml);

		while ((m = ml_dequeue(&ml0)) != NULL) {
			if ((*ifp->if_bpf_mtap)(if_bpf, m, BPF_DIRECTION_IN)) {
				m_freem(m);
				fdrops++;
			} else
				ml_enqueue(ml, m);
		}

		if (ml_empty(ml)) {
			mtx_enter(&ifiq->ifiq_mtx);
			ifiq->ifiq_packets += packets;
			ifiq->ifiq_bytes += bytes;
			ifiq->ifiq_fdrops += fdrops;
			mtx_leave(&ifiq->ifiq_mtx);

			return (0);
		}
	}
#endif

	mtx_enter(&ifiq->ifiq_mtx);
	ifiq->ifiq_packets += packets;
	ifiq->ifiq_bytes += bytes;
	ifiq->ifiq_fdrops += fdrops;

	len = ml_len(&ifiq->ifiq_ml);
	if (__predict_true(!ISSET(ifp->if_xflags, IFXF_MONITOR))) {
		if (len > ifiq_maxlen_drop)
			ifiq->ifiq_qdrops += ml_len(ml);
		else {
			ifiq->ifiq_enqueues++;
			ml_enlist(&ifiq->ifiq_ml, ml);
		}
	}
	mtx_leave(&ifiq->ifiq_mtx);

	if (ml_empty(ml))
		task_add(ifiq->ifiq_softnet, &ifiq->ifiq_task);
	else
		ml_purge(ml);

	return (len > ifiq_maxlen_return);
}

void
ifiq_add_data(struct ifiqueue *ifiq, struct if_data *data)
{
	mtx_enter(&ifiq->ifiq_mtx);
	data->ifi_ipackets += ifiq->ifiq_packets;
	data->ifi_ibytes += ifiq->ifiq_bytes;
	data->ifi_iqdrops += ifiq->ifiq_qdrops;
	mtx_leave(&ifiq->ifiq_mtx);
}

int
ifiq_enqueue(struct ifiqueue *ifiq, struct mbuf *m)
{
	struct ifnet *ifp = ifiq->ifiq_if;
#if NBPFILTER > 0
	caddr_t if_bpf = ifp->if_bpf;
#endif

	m->m_pkthdr.ph_ifidx = ifp->if_index;
	m->m_pkthdr.ph_rtableid = ifp->if_rdomain;

#if NBPFILTER > 0
	if_bpf = ifp->if_bpf;
	if (if_bpf) {
		if ((*ifp->if_bpf_mtap)(if_bpf, m, BPF_DIRECTION_IN)) {
			mtx_enter(&ifiq->ifiq_mtx);
			ifiq->ifiq_packets++;
			ifiq->ifiq_bytes += m->m_pkthdr.len;
			ifiq->ifiq_fdrops++;
			mtx_leave(&ifiq->ifiq_mtx);

			m_freem(m);
			return (0);
		}
	}
#endif

	mtx_enter(&ifiq->ifiq_mtx);
	ifiq->ifiq_packets++;
	ifiq->ifiq_bytes += m->m_pkthdr.len;
	ifiq->ifiq_enqueues++;
	ml_enqueue(&ifiq->ifiq_ml, m);
	mtx_leave(&ifiq->ifiq_mtx);

	task_add(ifiq->ifiq_softnet, &ifiq->ifiq_task);

	return (0);
}

static void
ifiq_process(void *arg)
{
	struct ifiqueue *ifiq = arg;
	struct mbuf_list ml;

	if (ifiq_empty(ifiq))
		return;

	mtx_enter(&ifiq->ifiq_mtx);
	ifiq->ifiq_dequeues++;
	ml = ifiq->ifiq_ml;
	ml_init(&ifiq->ifiq_ml);
	mtx_leave(&ifiq->ifiq_mtx);

	if_input_process(ifiq->ifiq_if, &ml);
}

int
net_ifiq_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, 
    void *newp, size_t newlen)
{
	int error = EOPNOTSUPP;
/* pressure is disabled for 6.6-release */
#if 0
	int val;

	if (namelen != 1)
		return (EISDIR);

	switch (name[0]) {
	case NET_LINK_IFRXQ_PRESSURE_RETURN:
		val = ifiq_pressure_return;
		error = sysctl_int(oldp, oldlenp, newp, newlen, &val);
		if (error != 0)
			return (error);
		if (val < 1 || val > ifiq_pressure_drop)
			return (EINVAL);
		ifiq_pressure_return = val;
		break;
	case NET_LINK_IFRXQ_PRESSURE_DROP:
		val = ifiq_pressure_drop;
		error = sysctl_int(oldp, oldlenp, newp, newlen, &val);
		if (error != 0)
			return (error);
		if (ifiq_pressure_return > val)
			return (EINVAL);
		ifiq_pressure_drop = val;
		break;
	default:
		error = EOPNOTSUPP;
		break;
	}
#endif

	return (error);
}

/*
 * priq implementation
 */

unsigned int
priq_idx(unsigned int nqueues, const struct mbuf *m)
{
	unsigned int flow = 0;

	if (ISSET(m->m_pkthdr.csum_flags, M_FLOWID))
		flow = m->m_pkthdr.ph_flowid;

	return (flow % nqueues);
}

void *
priq_alloc(unsigned int idx, void *null)
{
	struct priq *pq;
	int i;

	pq = malloc(sizeof(struct priq), M_DEVBUF, M_WAITOK);
	for (i = 0; i < IFQ_NQUEUES; i++)
		ml_init(&pq->pq_lists[i]);
	return (pq);
}

void
priq_free(unsigned int idx, void *pq)
{
	free(pq, M_DEVBUF, sizeof(struct priq));
}

struct mbuf *
priq_enq(struct ifqueue *ifq, struct mbuf *m)
{
	struct priq *pq;
	struct mbuf_list *pl;
	struct mbuf *n = NULL;
	unsigned int prio;

	pq = ifq->ifq_q;
	KASSERT(m->m_pkthdr.pf.prio <= IFQ_MAXPRIO);

	/* Find a lower priority queue to drop from */
	if (ifq_len(ifq) >= ifq->ifq_maxlen) {
		for (prio = 0; prio < m->m_pkthdr.pf.prio; prio++) {
			pl = &pq->pq_lists[prio];
			if (ml_len(pl) > 0) {
				n = ml_dequeue(pl);
				goto enqueue;
			}
		}
		/*
		 * There's no lower priority queue that we can
		 * drop from so don't enqueue this one.
		 */
		return (m);
	}

 enqueue:
	pl = &pq->pq_lists[m->m_pkthdr.pf.prio];
	ml_enqueue(pl, m);

	return (n);
}

struct mbuf *
priq_deq_begin(struct ifqueue *ifq, void **cookiep)
{
	struct priq *pq = ifq->ifq_q;
	struct mbuf_list *pl;
	unsigned int prio = nitems(pq->pq_lists);
	struct mbuf *m;

	do {
		pl = &pq->pq_lists[--prio];
		m = MBUF_LIST_FIRST(pl);
		if (m != NULL) {
			*cookiep = pl;
			return (m);
		}
	} while (prio > 0);

	return (NULL);
}

void
priq_deq_commit(struct ifqueue *ifq, struct mbuf *m, void *cookie)
{
	struct mbuf_list *pl = cookie;

	KASSERT(MBUF_LIST_FIRST(pl) == m);

	ml_dequeue(pl);
}

void
priq_purge(struct ifqueue *ifq, struct mbuf_list *ml)
{
	struct priq *pq = ifq->ifq_q;
	struct mbuf_list *pl;
	unsigned int prio = nitems(pq->pq_lists);

	do {
		pl = &pq->pq_lists[--prio];
		ml_enlist(ml, pl);
	} while (prio > 0);
}