FreeBSD/Linux Kernel Cross Reference
sys/net/if.c

     /*      $NetBSD: if.c,v 1.528 2022/11/25 06:18:42 msaitoh Exp $ */
     
     /*-
      * Copyright (c) 1999, 2000, 2001, 2008 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by William Studenmund and Jason R. Thorpe.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     * POSSIBILITY OF SUCH DAMAGE.
     */
    
    /*
     * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
     * All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the project nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    /*
     * Copyright (c) 1980, 1986, 1993
     *      The Regents of the University of California.  All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)if.c        8.5 (Berkeley) 1/9/95
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: if.c,v 1.528 2022/11/25 06:18:42 msaitoh Exp $");
    
    #if defined(_KERNEL_OPT)
    #include "opt_inet.h"
    #include "opt_ipsec.h"
    #include "opt_atalk.h"
    #include "opt_wlan.h"
   #include "opt_net_mpsafe.h"
   #include "opt_mrouting.h"
   #endif
   
   #include <sys/param.h>
   #include <sys/mbuf.h>
   #include <sys/systm.h>
   #include <sys/callout.h>
   #include <sys/proc.h>
   #include <sys/socket.h>
   #include <sys/socketvar.h>
   #include <sys/domain.h>
   #include <sys/protosw.h>
   #include <sys/kernel.h>
   #include <sys/ioctl.h>
   #include <sys/sysctl.h>
   #include <sys/syslog.h>
   #include <sys/kauth.h>
   #include <sys/kmem.h>
   #include <sys/xcall.h>
   #include <sys/cpu.h>
   #include <sys/intr.h>
   #include <sys/module_hook.h>
   #include <sys/compat_stub.h>
   #include <sys/msan.h>
   #include <sys/hook.h>
   
   #include <net/if.h>
   #include <net/if_dl.h>
   #include <net/if_ether.h>
   #include <net/if_media.h>
   #include <net80211/ieee80211.h>
   #include <net80211/ieee80211_ioctl.h>
   #include <net/if_types.h>
   #include <net/route.h>
   #include <sys/module.h>
   #ifdef NETATALK
   #include <netatalk/at_extern.h>
   #include <netatalk/at.h>
   #endif
   #include <net/pfil.h>
   #include <netinet/in.h>
   #include <netinet/in_var.h>
   #include <netinet/ip_encap.h>
   #include <net/bpf.h>
   
   #ifdef INET6
   #include <netinet6/in6_var.h>
   #include <netinet6/nd6.h>
   #endif
   
   #include "ether.h"
   
   #include "bridge.h"
   #if NBRIDGE > 0
   #include <net/if_bridgevar.h>
   #endif
   
   #include "carp.h"
   #if NCARP > 0
   #include <netinet/ip_carp.h>
   #endif
   
   #include <compat/sys/sockio.h>
   
   MALLOC_DEFINE(M_IFADDR, "ifaddr", "interface address");
   MALLOC_DEFINE(M_IFMADDR, "ether_multi", "link-level multicast address");
   
   /*
    * XXX reusing (ifp)->if_snd->ifq_lock rather than having another spin mutex
    * for each ifnet.  It doesn't matter because:
    * - if IFEF_MPSAFE is enabled, if_snd isn't used and lock contentions on
    *   ifq_lock don't happen
    * - if IFEF_MPSAFE is disabled, there is no lock contention on ifq_lock
    *   because if_snd, if_link_state_change and if_link_state_change_process
    *   are all called with KERNEL_LOCK
    */
   #define IF_LINK_STATE_CHANGE_LOCK(ifp)          \
           mutex_enter((ifp)->if_snd.ifq_lock)
   #define IF_LINK_STATE_CHANGE_UNLOCK(ifp)        \
           mutex_exit((ifp)->if_snd.ifq_lock)
   
   /*
    * Global list of interfaces.
    */
   /* DEPRECATED. Remove it once kvm(3) users disappeared */
   struct ifnet_head               ifnet_list;
   
   struct pslist_head              ifnet_pslist;
   static ifnet_t **               ifindex2ifnet = NULL;
   static u_int                    if_index = 1;
   static size_t                   if_indexlim = 0;
   static uint64_t                 index_gen;
   /* Mutex to protect the above objects. */
   kmutex_t                        ifnet_mtx __cacheline_aligned;
   static struct psref_class       *ifnet_psref_class __read_mostly;
   static pserialize_t             ifnet_psz;
   static struct workqueue         *ifnet_link_state_wq __read_mostly;
   
   static struct workqueue         *if_slowtimo_wq __read_mostly;
   
   static kmutex_t                 if_clone_mtx;
   
   struct ifnet *lo0ifp;
   int     ifqmaxlen = IFQ_MAXLEN;
   
   struct psref_class              *ifa_psref_class __read_mostly;
   
   static int      if_delroute_matcher(struct rtentry *, void *);
   
   static bool if_is_unit(const char *);
   static struct if_clone *if_clone_lookup(const char *, int *);
   
   static LIST_HEAD(, if_clone) if_cloners = LIST_HEAD_INITIALIZER(if_cloners);
   static int if_cloners_count;
   
   /* Packet filtering hook for interfaces. */
   pfil_head_t *                   if_pfil __read_mostly;
   
   static kauth_listener_t if_listener;
   
   static int doifioctl(struct socket *, u_long, void *, struct lwp *);
   static void sysctl_sndq_setup(struct sysctllog **, const char *,
       struct ifaltq *);
   static void if_slowtimo_intr(void *);
   static void if_slowtimo_work(struct work *, void *);
   static int sysctl_if_watchdog(SYSCTLFN_PROTO);
   static void sysctl_watchdog_setup(struct ifnet *);
   static void if_attachdomain1(struct ifnet *);
   static int ifconf(u_long, void *);
   static int if_transmit(struct ifnet *, struct mbuf *);
   static int if_clone_create(const char *);
   static int if_clone_destroy(const char *);
   static void if_link_state_change_work(struct work *, void *);
   static void if_up_locked(struct ifnet *);
   static void _if_down(struct ifnet *);
   static void if_down_deactivated(struct ifnet *);
   
   struct if_percpuq {
           struct ifnet    *ipq_ifp;
           void            *ipq_si;
           struct percpu   *ipq_ifqs;      /* struct ifqueue */
   };
   
   static struct mbuf *if_percpuq_dequeue(struct if_percpuq *);
   
   static void if_percpuq_drops(void *, void *, struct cpu_info *);
   static int sysctl_percpuq_drops_handler(SYSCTLFN_PROTO);
   static void sysctl_percpuq_setup(struct sysctllog **, const char *,
       struct if_percpuq *);
   
   struct if_deferred_start {
           struct ifnet    *ids_ifp;
           void            (*ids_if_start)(struct ifnet *);
           void            *ids_si;
   };
   
   static void if_deferred_start_softint(void *);
   static void if_deferred_start_common(struct ifnet *);
   static void if_deferred_start_destroy(struct ifnet *);
   
   struct if_slowtimo_data {
           kmutex_t                isd_lock;
           struct callout          isd_ch;
           struct work             isd_work;
           struct ifnet            *isd_ifp;
           bool                    isd_queued;
           bool                    isd_dying;
           bool                    isd_trigger;
   };
   
   /*
    * Hook for if_vlan - needed by if_agr
    */
   struct if_vlan_vlan_input_hook_t if_vlan_vlan_input_hook;
   
   static void if_sysctl_setup(struct sysctllog **);
   
   static int
   if_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie,
       void *arg0, void *arg1, void *arg2, void *arg3)
   {
           int result;
           enum kauth_network_req req;
   
           result = KAUTH_RESULT_DEFER;
           req = (enum kauth_network_req)(uintptr_t)arg1;
   
           if (action != KAUTH_NETWORK_INTERFACE)
                   return result;
   
           if ((req == KAUTH_REQ_NETWORK_INTERFACE_GET) ||
               (req == KAUTH_REQ_NETWORK_INTERFACE_SET))
                   result = KAUTH_RESULT_ALLOW;
   
           return result;
   }
   
   /*
    * Network interface utility routines.
    *
    * Routines with ifa_ifwith* names take sockaddr *'s as
    * parameters.
    */
   void
   ifinit(void)
   {
   
   #if (defined(INET) || defined(INET6))
           encapinit();
   #endif
   
           if_listener = kauth_listen_scope(KAUTH_SCOPE_NETWORK,
               if_listener_cb, NULL);
   
           /* interfaces are available, inform socket code */
           ifioctl = doifioctl;
   }
   
   /*
    * XXX Initialization before configure().
    * XXX hack to get pfil_add_hook working in autoconf.
    */
   void
   ifinit1(void)
   {
           int error __diagused;
   
   #ifdef NET_MPSAFE
           printf("NET_MPSAFE enabled\n");
   #endif
   
           mutex_init(&if_clone_mtx, MUTEX_DEFAULT, IPL_NONE);
   
           TAILQ_INIT(&ifnet_list);
           mutex_init(&ifnet_mtx, MUTEX_DEFAULT, IPL_NONE);
           ifnet_psz = pserialize_create();
           ifnet_psref_class = psref_class_create("ifnet", IPL_SOFTNET);
           ifa_psref_class = psref_class_create("ifa", IPL_SOFTNET);
           error = workqueue_create(&ifnet_link_state_wq, "iflnkst",
               if_link_state_change_work, NULL, PRI_SOFTNET, IPL_NET,
               WQ_MPSAFE);
           KASSERT(error == 0);
           PSLIST_INIT(&ifnet_pslist);
   
           error = workqueue_create(&if_slowtimo_wq, "ifwdog",
               if_slowtimo_work, NULL, PRI_SOFTNET, IPL_SOFTCLOCK, WQ_MPSAFE);
           KASSERTMSG(error == 0, "error=%d", error);
   
           if_indexlim = 8;
   
           if_pfil = pfil_head_create(PFIL_TYPE_IFNET, NULL);
           KASSERT(if_pfil != NULL);
   
   #if NETHER > 0 || defined(NETATALK) || defined(WLAN)
           etherinit();
   #endif
   }
   
   /* XXX must be after domaininit() */
   void
   ifinit_post(void)
   {
   
           if_sysctl_setup(NULL);
   }
   
   ifnet_t *
   if_alloc(u_char type)
   {
   
           return kmem_zalloc(sizeof(ifnet_t), KM_SLEEP);
   }
   
   void
   if_free(ifnet_t *ifp)
   {
   
           kmem_free(ifp, sizeof(ifnet_t));
   }
   
   void
   if_initname(struct ifnet *ifp, const char *name, int unit)
   {
   
           (void)snprintf(ifp->if_xname, sizeof(ifp->if_xname),
               "%s%d", name, unit);
   }
   
   /*
    * Null routines used while an interface is going away.  These routines
    * just return an error.
    */
   
   int
   if_nulloutput(struct ifnet *ifp, struct mbuf *m,
       const struct sockaddr *so, const struct rtentry *rt)
   {
   
           return ENXIO;
   }
   
   void
   if_nullinput(struct ifnet *ifp, struct mbuf *m)
   {
   
           /* Nothing. */
   }
   
   void
   if_nullstart(struct ifnet *ifp)
   {
   
           /* Nothing. */
   }
   
   int
   if_nulltransmit(struct ifnet *ifp, struct mbuf *m)
   {
   
           m_freem(m);
           return ENXIO;
   }
   
   int
   if_nullioctl(struct ifnet *ifp, u_long cmd, void *data)
   {
   
           return ENXIO;
   }
   
   int
   if_nullinit(struct ifnet *ifp)
   {
   
           return ENXIO;
   }
   
   void
   if_nullstop(struct ifnet *ifp, int disable)
   {
   
           /* Nothing. */
   }
   
   void
   if_nullslowtimo(struct ifnet *ifp)
   {
   
           /* Nothing. */
   }
   
   void
   if_nulldrain(struct ifnet *ifp)
   {
   
           /* Nothing. */
   }
   
   void
   if_set_sadl(struct ifnet *ifp, const void *lla, u_char addrlen, bool factory)
   {
           struct ifaddr *ifa;
           struct sockaddr_dl *sdl;
   
           ifp->if_addrlen = addrlen;
           if_alloc_sadl(ifp);
           ifa = ifp->if_dl;
           sdl = satosdl(ifa->ifa_addr);
   
           (void)sockaddr_dl_setaddr(sdl, sdl->sdl_len, lla, ifp->if_addrlen);
           if (factory) {
                   KASSERT(ifp->if_hwdl == NULL);
                   ifp->if_hwdl = ifp->if_dl;
                   ifaref(ifp->if_hwdl);
           }
           /* TBD routing socket */
   }
   
   struct ifaddr *
   if_dl_create(const struct ifnet *ifp, const struct sockaddr_dl **sdlp)
   {
           unsigned socksize, ifasize;
           int addrlen, namelen;
           struct sockaddr_dl *mask, *sdl;
           struct ifaddr *ifa;
   
           namelen = strlen(ifp->if_xname);
           addrlen = ifp->if_addrlen;
           socksize = roundup(sockaddr_dl_measure(namelen, addrlen),
               sizeof(long));
           ifasize = sizeof(*ifa) + 2 * socksize;
           ifa = malloc(ifasize, M_IFADDR, M_WAITOK | M_ZERO);
   
           sdl = (struct sockaddr_dl *)(ifa + 1);
           mask = (struct sockaddr_dl *)(socksize + (char *)sdl);
   
           sockaddr_dl_init(sdl, socksize, ifp->if_index, ifp->if_type,
               ifp->if_xname, namelen, NULL, addrlen);
           mask->sdl_family = AF_LINK;
           mask->sdl_len = sockaddr_dl_measure(namelen, 0);
           memset(&mask->sdl_data[0], 0xff, namelen);
           ifa->ifa_rtrequest = link_rtrequest;
           ifa->ifa_addr = (struct sockaddr *)sdl;
           ifa->ifa_netmask = (struct sockaddr *)mask;
           ifa_psref_init(ifa);
   
           *sdlp = sdl;
   
           return ifa;
   }
   
   static void
   if_sadl_setrefs(struct ifnet *ifp, struct ifaddr *ifa)
   {
           const struct sockaddr_dl *sdl;
   
           ifp->if_dl = ifa;
           ifaref(ifa);
           sdl = satosdl(ifa->ifa_addr);
           ifp->if_sadl = sdl;
   }
   
   /*
    * Allocate the link level name for the specified interface.  This
    * is an attachment helper.  It must be called after ifp->if_addrlen
    * is initialized, which may not be the case when if_attach() is
    * called.
    */
   void
   if_alloc_sadl(struct ifnet *ifp)
   {
           struct ifaddr *ifa;
           const struct sockaddr_dl *sdl;
   
           /*
            * If the interface already has a link name, release it
            * now.  This is useful for interfaces that can change
            * link types, and thus switch link names often.
            */
           if (ifp->if_sadl != NULL)
                   if_free_sadl(ifp, 0);
   
           ifa = if_dl_create(ifp, &sdl);
   
           ifa_insert(ifp, ifa);
           if_sadl_setrefs(ifp, ifa);
   }
   
   static void
   if_deactivate_sadl(struct ifnet *ifp)
   {
           struct ifaddr *ifa;
   
           KASSERT(ifp->if_dl != NULL);
   
           ifa = ifp->if_dl;
   
           ifp->if_sadl = NULL;
   
           ifp->if_dl = NULL;
           ifafree(ifa);
   }
   
   static void
   if_replace_sadl(struct ifnet *ifp, struct ifaddr *ifa)
   {
           struct ifaddr *old;
   
           KASSERT(ifp->if_dl != NULL);
   
           old = ifp->if_dl;
   
           ifaref(ifa);
           /* XXX Update if_dl and if_sadl atomically */
           ifp->if_dl = ifa;
           ifp->if_sadl = satosdl(ifa->ifa_addr);
   
           ifafree(old);
   }
   
   void
   if_activate_sadl(struct ifnet *ifp, struct ifaddr *ifa0,
       const struct sockaddr_dl *sdl)
   {
           struct ifaddr *ifa;
           const int bound = curlwp_bind();
   
           KASSERT(ifa_held(ifa0));
   
           const int s = splsoftnet();
   
           if_replace_sadl(ifp, ifa0);
   
           int ss = pserialize_read_enter();
           IFADDR_READER_FOREACH(ifa, ifp) {
                   struct psref psref;
                   ifa_acquire(ifa, &psref);
                   pserialize_read_exit(ss);
   
                   rtinit(ifa, RTM_LLINFO_UPD, 0);
   
                   ss = pserialize_read_enter();
                   ifa_release(ifa, &psref);
           }
           pserialize_read_exit(ss);
   
           splx(s);
           curlwp_bindx(bound);
   }
   
   /*
    * Free the link level name for the specified interface.  This is
    * a detach helper.  This is called from if_detach().
    */
   void
   if_free_sadl(struct ifnet *ifp, int factory)
   {
           struct ifaddr *ifa;
   
           if (factory && ifp->if_hwdl != NULL) {
                   ifa = ifp->if_hwdl;
                   ifp->if_hwdl = NULL;
                   ifafree(ifa);
           }
   
           ifa = ifp->if_dl;
           if (ifa == NULL) {
                   KASSERT(ifp->if_sadl == NULL);
                   return;
           }
   
           KASSERT(ifp->if_sadl != NULL);
   
           const int s = splsoftnet();
           KASSERT(ifa->ifa_addr->sa_family == AF_LINK);
           ifa_remove(ifp, ifa);
           if_deactivate_sadl(ifp);
           splx(s);
   }
   
   static void
   if_getindex(ifnet_t *ifp)
   {
           bool hitlimit = false;
           char xnamebuf[HOOKNAMSIZ];
   
           ifp->if_index_gen = index_gen++;
           snprintf(xnamebuf, sizeof(xnamebuf), "%s-lshk", ifp->if_xname);
           ifp->if_linkstate_hooks = simplehook_create(IPL_NET,
               xnamebuf);
   
           ifp->if_index = if_index;
           if (ifindex2ifnet == NULL) {
                   if_index++;
                   goto skip;
           }
           while (if_byindex(ifp->if_index)) {
                   /*
                    * If we hit USHRT_MAX, we skip back to 0 since
                    * there are a number of places where the value
                    * of if_index or if_index itself is compared
                    * to or stored in an unsigned short.  By
                    * jumping back, we won't botch those assignments
                    * or comparisons.
                    */
                   if (++if_index == 0) {
                           if_index = 1;
                   } else if (if_index == USHRT_MAX) {
                           /*
                            * However, if we have to jump back to
                            * zero *twice* without finding an empty
                            * slot in ifindex2ifnet[], then there
                            * there are too many (>65535) interfaces.
                            */
                           if (hitlimit)
                                   panic("too many interfaces");
                           hitlimit = true;
                           if_index = 1;
                   }
                   ifp->if_index = if_index;
           }
   skip:
           /*
            * ifindex2ifnet is indexed by if_index. Since if_index will
            * grow dynamically, it should grow too.
            */
           if (ifindex2ifnet == NULL || ifp->if_index >= if_indexlim) {
                   size_t m, n, oldlim;
                   void *q;
   
                   oldlim = if_indexlim;
                   while (ifp->if_index >= if_indexlim)
                           if_indexlim <<= 1;
   
                   /* grow ifindex2ifnet */
                   m = oldlim * sizeof(struct ifnet *);
                   n = if_indexlim * sizeof(struct ifnet *);
                   q = malloc(n, M_IFADDR, M_WAITOK | M_ZERO);
                   if (ifindex2ifnet != NULL) {
                           memcpy(q, ifindex2ifnet, m);
                           free(ifindex2ifnet, M_IFADDR);
                   }
                   ifindex2ifnet = (struct ifnet **)q;
           }
           ifindex2ifnet[ifp->if_index] = ifp;
   }
   
   /*
    * Initialize an interface and assign an index for it.
    *
    * It must be called prior to a device specific attach routine
    * (e.g., ether_ifattach and ieee80211_ifattach) or if_alloc_sadl,
    * and be followed by if_register:
    *
    *     if_initialize(ifp);
    *     ether_ifattach(ifp, enaddr);
    *     if_register(ifp);
    */
   void
   if_initialize(ifnet_t *ifp)
   {
   
           KASSERT(if_indexlim > 0);
           TAILQ_INIT(&ifp->if_addrlist);
   
           /*
            * Link level name is allocated later by a separate call to
            * if_alloc_sadl().
            */
   
           if (ifp->if_snd.ifq_maxlen == 0)
                   ifp->if_snd.ifq_maxlen = ifqmaxlen;
   
           ifp->if_broadcastaddr = 0; /* reliably crash if used uninitialized */
   
           ifp->if_link_state = LINK_STATE_UNKNOWN;
           ifp->if_link_queue = -1; /* all bits set, see link_state_change() */
           ifp->if_link_scheduled = false;
   
           ifp->if_capenable = 0;
           ifp->if_csum_flags_tx = 0;
           ifp->if_csum_flags_rx = 0;
   
   #ifdef ALTQ
           ifp->if_snd.altq_type = 0;
           ifp->if_snd.altq_disc = NULL;
           ifp->if_snd.altq_flags &= ALTQF_CANTCHANGE;
           ifp->if_snd.altq_tbr  = NULL;
           ifp->if_snd.altq_ifp  = ifp;
   #endif
   
           IFQ_LOCK_INIT(&ifp->if_snd);
   
           ifp->if_pfil = pfil_head_create(PFIL_TYPE_IFNET, ifp);
           pfil_run_ifhooks(if_pfil, PFIL_IFNET_ATTACH, ifp);
   
           IF_AFDATA_LOCK_INIT(ifp);
   
           PSLIST_ENTRY_INIT(ifp, if_pslist_entry);
           PSLIST_INIT(&ifp->if_addr_pslist);
           psref_target_init(&ifp->if_psref, ifnet_psref_class);
           ifp->if_ioctl_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
           LIST_INIT(&ifp->if_multiaddrs);
           if_stats_init(ifp);
   
           IFNET_GLOBAL_LOCK();
           if_getindex(ifp);
           IFNET_GLOBAL_UNLOCK();
   }
   
   /*
    * Register an interface to the list of "active" interfaces.
    */
   void
   if_register(ifnet_t *ifp)
   {
           /*
            * If the driver has not supplied its own if_ioctl or if_stop,
            * then supply the default.
            */
           if (ifp->if_ioctl == NULL)
                   ifp->if_ioctl = ifioctl_common;
           if (ifp->if_stop == NULL)
                   ifp->if_stop = if_nullstop;
   
           sysctl_sndq_setup(&ifp->if_sysctl_log, ifp->if_xname, &ifp->if_snd);
   
           if (!STAILQ_EMPTY(&domains))
                   if_attachdomain1(ifp);
   
           /* Announce the interface. */
           rt_ifannouncemsg(ifp, IFAN_ARRIVAL);
   
           if (ifp->if_slowtimo != NULL) {
                   struct if_slowtimo_data *isd;
   
                   isd = kmem_zalloc(sizeof(*isd), KM_SLEEP);
                   mutex_init(&isd->isd_lock, MUTEX_DEFAULT, IPL_SOFTCLOCK);
                   callout_init(&isd->isd_ch, CALLOUT_MPSAFE);
                   callout_setfunc(&isd->isd_ch, if_slowtimo_intr, ifp);
                   isd->isd_ifp = ifp;
   
                   ifp->if_slowtimo_data = isd;
   
                   if_slowtimo_intr(ifp);
   
                   sysctl_watchdog_setup(ifp);
           }
   
           if (ifp->if_transmit == NULL || ifp->if_transmit == if_nulltransmit)
                   ifp->if_transmit = if_transmit;
   
           IFNET_GLOBAL_LOCK();
           TAILQ_INSERT_TAIL(&ifnet_list, ifp, if_list);
           IFNET_WRITER_INSERT_TAIL(ifp);
           IFNET_GLOBAL_UNLOCK();
   }
   
   /*
    * The if_percpuq framework
    *
    * It allows network device drivers to execute the network stack
    * in softint (so called softint-based if_input). It utilizes
    * softint and percpu ifqueue. It doesn't distribute any packets
    * between CPUs, unlike pktqueue(9).
    *
    * Currently we support two options for device drivers to apply the framework:
    * - Use it implicitly with less changes
    *   - If you use if_attach in driver's _attach function and if_input in
    *     driver's Rx interrupt handler, a packet is queued and a softint handles
    *     the packet implicitly
    * - Use it explicitly in each driver (recommended)
    *   - You can use if_percpuq_* directly in your driver
    *   - In this case, you need to allocate struct if_percpuq in driver's softc
    *   - See wm(4) as a reference implementation
    */
   
   static void
   if_percpuq_softint(void *arg)
   {
           struct if_percpuq *ipq = arg;
           struct ifnet *ifp = ipq->ipq_ifp;
           struct mbuf *m;
   
           while ((m = if_percpuq_dequeue(ipq)) != NULL) {
                   if_statinc(ifp, if_ipackets);
                   bpf_mtap(ifp, m, BPF_D_IN);
   
                   ifp->_if_input(ifp, m);
           }
   }
   
   static void
   if_percpuq_init_ifq(void *p, void *arg __unused, struct cpu_info *ci __unused)
   {
           struct ifqueue *const ifq = p;
   
           memset(ifq, 0, sizeof(*ifq));
           ifq->ifq_maxlen = IFQ_MAXLEN;
   }
   
   struct if_percpuq *
   if_percpuq_create(struct ifnet *ifp)
   {
           struct if_percpuq *ipq;
           u_int flags = SOFTINT_NET;
   
           flags |= if_is_mpsafe(ifp) ? SOFTINT_MPSAFE : 0;
   
           ipq = kmem_zalloc(sizeof(*ipq), KM_SLEEP);
           ipq->ipq_ifp = ifp;
           ipq->ipq_si = softint_establish(flags, if_percpuq_softint, ipq);
           ipq->ipq_ifqs = percpu_alloc(sizeof(struct ifqueue));
           percpu_foreach(ipq->ipq_ifqs, &if_percpuq_init_ifq, NULL);
   
           sysctl_percpuq_setup(&ifp->if_sysctl_log, ifp->if_xname, ipq);
   
           return ipq;
   }
   
   static struct mbuf *
   if_percpuq_dequeue(struct if_percpuq *ipq)
   {
           struct mbuf *m;
           struct ifqueue *ifq;
   
           const int s = splnet();
           ifq = percpu_getref(ipq->ipq_ifqs);
           IF_DEQUEUE(ifq, m);
           percpu_putref(ipq->ipq_ifqs);
           splx(s);
   
           return m;
   }
   
   static void
   if_percpuq_purge_ifq(void *p, void *arg __unused, struct cpu_info *ci __unused)
   {
           struct ifqueue *const ifq = p;
   
           IF_PURGE(ifq);
   }
   
   void
   if_percpuq_destroy(struct if_percpuq *ipq)
   {
   
           /* if_detach may already destroy it */
           if (ipq == NULL)
                   return;
   
           softint_disestablish(ipq->ipq_si);
           percpu_foreach(ipq->ipq_ifqs, &if_percpuq_purge_ifq, NULL);
           percpu_free(ipq->ipq_ifqs, sizeof(struct ifqueue));
           kmem_free(ipq, sizeof(*ipq));
   }
   
   void
   if_percpuq_enqueue(struct if_percpuq *ipq, struct mbuf *m)
   {
           struct ifqueue *ifq;
   
           KASSERT(ipq != NULL);
   
           const int s = splnet();
           ifq = percpu_getref(ipq->ipq_ifqs);
           if (IF_QFULL(ifq)) {
                   IF_DROP(ifq);
                   percpu_putref(ipq->ipq_ifqs);
                   m_freem(m);
                   goto out;
           }
           IF_ENQUEUE(ifq, m);
           percpu_putref(ipq->ipq_ifqs);
   
           softint_schedule(ipq->ipq_si);
   out:
           splx(s);
   }
   
   static void
   if_percpuq_drops(void *p, void *arg, struct cpu_info *ci __unused)
   {
           struct ifqueue *const ifq = p;
           uint64_t *sum = arg;
   
           *sum += ifq->ifq_drops;
   }
   
   static int
   sysctl_percpuq_drops_handler(SYSCTLFN_ARGS)
   {
           struct sysctlnode node;
           struct if_percpuq *ipq;
           uint64_t sum = 0;
           int error;
   
           node = *rnode;
           ipq = node.sysctl_data;
   
           percpu_foreach(ipq->ipq_ifqs, if_percpuq_drops, &sum);
   
           node.sysctl_data = &sum;
           error = sysctl_lookup(SYSCTLFN_CALL(&node));
           if (error != 0 || newp == NULL)
                   return error;
   
           return 0;
   }
   
   static void
   sysctl_percpuq_setup(struct sysctllog **clog, const char* ifname,
       struct if_percpuq *ipq)
   {
           const struct sysctlnode *cnode, *rnode;
   
           if (sysctl_createv(clog, 0, NULL, &rnode,
                          CTLFLAG_PERMANENT,
                          CTLTYPE_NODE, "interfaces",
                          SYSCTL_DESCR("Per-interface controls"),
                          NULL, 0, NULL, 0,
                          CTL_NET, CTL_CREATE, CTL_EOL) != 0)
                   goto bad;
   
           if (sysctl_createv(clog, 0, &rnode, &rnode,
                          CTLFLAG_PERMANENT,
                          CTLTYPE_NODE, ifname,
                          SYSCTL_DESCR("Interface controls"),
                          NULL, 0, NULL, 0,
                          CTL_CREATE, CTL_EOL) != 0)
                   goto bad;
   
           if (sysctl_createv(clog, 0, &rnode, &rnode,
                          CTLFLAG_PERMANENT,
                          CTLTYPE_NODE, "rcvq",
                          SYSCTL_DESCR("Interface input queue controls"),
                          NULL, 0, NULL, 0,
                          CTL_CREATE, CTL_EOL) != 0)
                   goto bad;
  
  #ifdef NOTYET
          /* XXX Should show each per-CPU queue length? */
          if (sysctl_createv(clog, 0, &rnode, &rnode,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_INT, "len",
                         SYSCTL_DESCR("Current input queue length"),
                         sysctl_percpuq_len, 0, NULL, 0,
                         CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
  
          if (sysctl_createv(clog, 0, &rnode, &cnode,
                         CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
                         CTLTYPE_INT, "maxlen",
                         SYSCTL_DESCR("Maximum allowed input queue length"),
                         sysctl_percpuq_maxlen_handler, 0, (void *)ipq, 0,
                         CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
  #endif
  
          if (sysctl_createv(clog, 0, &rnode, &cnode,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_QUAD, "drops",
                         SYSCTL_DESCR("Total packets dropped due to full input queue"),
                         sysctl_percpuq_drops_handler, 0, (void *)ipq, 0,
                         CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
  
          return;
  bad:
          printf("%s: could not attach sysctl nodes\n", ifname);
          return;
  }
  
  /*
   * The deferred if_start framework
   *
   * The common APIs to defer if_start to softint when if_start is requested
   * from a device driver running in hardware interrupt context.
   */
  /*
   * Call ifp->if_start (or equivalent) in a dedicated softint for
   * deferred if_start.
   */
  static void
  if_deferred_start_softint(void *arg)
  {
          struct if_deferred_start *ids = arg;
          struct ifnet *ifp = ids->ids_ifp;
  
          ids->ids_if_start(ifp);
  }
  
  /*
   * The default callback function for deferred if_start.
   */
  static void
  if_deferred_start_common(struct ifnet *ifp)
  {
          const int s = splnet();
          if_start_lock(ifp);
          splx(s);
  }
  
  static inline bool
  if_snd_is_used(struct ifnet *ifp)
  {
  
          return ALTQ_IS_ENABLED(&ifp->if_snd) ||
              ifp->if_transmit == if_transmit ||
              ifp->if_transmit == NULL ||
              ifp->if_transmit == if_nulltransmit;
  }
  
  /*
   * Schedule deferred if_start.
   */
  void
  if_schedule_deferred_start(struct ifnet *ifp)
  {
  
          KASSERT(ifp->if_deferred_start != NULL);
  
          if (if_snd_is_used(ifp) && IFQ_IS_EMPTY(&ifp->if_snd))
                  return;
  
          softint_schedule(ifp->if_deferred_start->ids_si);
  }
  
  /*
   * Create an instance of deferred if_start. A driver should call the function
   * only if the driver needs deferred if_start. Drivers can setup their own
   * deferred if_start function via 2nd argument.
   */
  void
  if_deferred_start_init(struct ifnet *ifp, void (*func)(struct ifnet *))
  {
          struct if_deferred_start *ids;
          u_int flags = SOFTINT_NET;
  
          flags |= if_is_mpsafe(ifp) ? SOFTINT_MPSAFE : 0;
  
          ids = kmem_zalloc(sizeof(*ids), KM_SLEEP);
          ids->ids_ifp = ifp;
          ids->ids_si = softint_establish(flags, if_deferred_start_softint, ids);
          if (func != NULL)
                  ids->ids_if_start = func;
          else
                  ids->ids_if_start = if_deferred_start_common;
  
          ifp->if_deferred_start = ids;
  }
  
  static void
  if_deferred_start_destroy(struct ifnet *ifp)
  {
  
          if (ifp->if_deferred_start == NULL)
                  return;
  
          softint_disestablish(ifp->if_deferred_start->ids_si);
          kmem_free(ifp->if_deferred_start, sizeof(*ifp->if_deferred_start));
          ifp->if_deferred_start = NULL;
  }
  
  /*
   * The common interface input routine that is called by device drivers,
   * which should be used only when the driver's rx handler already runs
   * in softint.
   */
  void
  if_input(struct ifnet *ifp, struct mbuf *m)
  {
  
          KASSERT(ifp->if_percpuq == NULL);
          KASSERT(!cpu_intr_p());
  
          if_statinc(ifp, if_ipackets);
          bpf_mtap(ifp, m, BPF_D_IN);
  
          ifp->_if_input(ifp, m);
  }
  
  /*
   * DEPRECATED. Use if_initialize and if_register instead.
   * See the above comment of if_initialize.
   *
   * Note that it implicitly enables if_percpuq to make drivers easy to
   * migrate softint-based if_input without much changes. If you don't
   * want to enable it, use if_initialize instead.
   */
  void
  if_attach(ifnet_t *ifp)
  {
  
          if_initialize(ifp);
          ifp->if_percpuq = if_percpuq_create(ifp);
          if_register(ifp);
  }
  
  void
  if_attachdomain(void)
  {
          struct ifnet *ifp;
          const int bound = curlwp_bind();
  
          int s = pserialize_read_enter();
          IFNET_READER_FOREACH(ifp) {
                  struct psref psref;
                  psref_acquire(&psref, &ifp->if_psref, ifnet_psref_class);
                  pserialize_read_exit(s);
                  if_attachdomain1(ifp);
                  s = pserialize_read_enter();
                  psref_release(&psref, &ifp->if_psref, ifnet_psref_class);
          }
          pserialize_read_exit(s);
          curlwp_bindx(bound);
  }
  
  static void
  if_attachdomain1(struct ifnet *ifp)
  {
          struct domain *dp;
          const int s = splsoftnet();
  
          /* address family dependent data region */
          memset(ifp->if_afdata, 0, sizeof(ifp->if_afdata));
          DOMAIN_FOREACH(dp) {
                  if (dp->dom_ifattach != NULL)
                          ifp->if_afdata[dp->dom_family] =
                              (*dp->dom_ifattach)(ifp);
          }
  
          splx(s);
  }
  
  /*
   * Deactivate an interface.  This points all of the procedure
   * handles at error stubs.  May be called from interrupt context.
   */
  void
  if_deactivate(struct ifnet *ifp)
  {
          const int s = splsoftnet();
  
          ifp->if_output   = if_nulloutput;
          ifp->_if_input   = if_nullinput;
          ifp->if_start    = if_nullstart;
          ifp->if_transmit = if_nulltransmit;
          ifp->if_ioctl    = if_nullioctl;
          ifp->if_init     = if_nullinit;
          ifp->if_stop     = if_nullstop;
          if (ifp->if_slowtimo)
                  ifp->if_slowtimo = if_nullslowtimo;
          ifp->if_drain    = if_nulldrain;
  
          /* No more packets may be enqueued. */
          ifp->if_snd.ifq_maxlen = 0;
  
          splx(s);
  }
  
  bool
  if_is_deactivated(const struct ifnet *ifp)
  {
  
          return ifp->if_output == if_nulloutput;
  }
  
  void
  if_purgeaddrs(struct ifnet *ifp, int family,
      void (*purgeaddr)(struct ifaddr *))
  {
          struct ifaddr *ifa, *nifa;
          int s;
  
          s = pserialize_read_enter();
          for (ifa = IFADDR_READER_FIRST(ifp); ifa; ifa = nifa) {
                  nifa = IFADDR_READER_NEXT(ifa);
                  if (ifa->ifa_addr->sa_family != family)
                          continue;
                  pserialize_read_exit(s);
  
                  (*purgeaddr)(ifa);
  
                  s = pserialize_read_enter();
          }
          pserialize_read_exit(s);
  }
  
  #ifdef IFAREF_DEBUG
  static struct ifaddr **ifa_list;
  static int ifa_list_size;
  
  /* Depends on only one if_attach runs at once */
  static void
  if_build_ifa_list(struct ifnet *ifp)
  {
          struct ifaddr *ifa;
          int i;
  
          KASSERT(ifa_list == NULL);
          KASSERT(ifa_list_size == 0);
  
          IFADDR_READER_FOREACH(ifa, ifp)
                  ifa_list_size++;
  
          ifa_list = kmem_alloc(sizeof(*ifa) * ifa_list_size, KM_SLEEP);
          i = 0;
          IFADDR_READER_FOREACH(ifa, ifp) {
                  ifa_list[i++] = ifa;
                  ifaref(ifa);
          }
  }
  
  static void
  if_check_and_free_ifa_list(struct ifnet *ifp)
  {
          int i;
          struct ifaddr *ifa;
  
          if (ifa_list == NULL)
                  return;
  
          for (i = 0; i < ifa_list_size; i++) {
                  char buf[64];
  
                  ifa = ifa_list[i];
                  sockaddr_format(ifa->ifa_addr, buf, sizeof(buf));
                  if (ifa->ifa_refcnt > 1) {
                          log(LOG_WARNING,
                              "ifa(%s) still referenced (refcnt=%d)\n",
                              buf, ifa->ifa_refcnt - 1);
                  } else
                          log(LOG_DEBUG,
                              "ifa(%s) not referenced (refcnt=%d)\n",
                              buf, ifa->ifa_refcnt - 1);
                  ifafree(ifa);
          }
  
          kmem_free(ifa_list, sizeof(*ifa) * ifa_list_size);
          ifa_list = NULL;
          ifa_list_size = 0;
  }
  #endif
  
  /*
   * Detach an interface from the list of "active" interfaces,
   * freeing any resources as we go along.
   *
   * NOTE: This routine must be called with a valid thread context,
   * as it may block.
   */
  void
  if_detach(struct ifnet *ifp)
  {
          struct socket so;
          struct ifaddr *ifa;
  #ifdef IFAREF_DEBUG
          struct ifaddr *last_ifa = NULL;
  #endif
          struct domain *dp;
          const struct protosw *pr;
          int i, family, purged;
  
  #ifdef IFAREF_DEBUG
          if_build_ifa_list(ifp);
  #endif
          /*
           * XXX It's kind of lame that we have to have the
           * XXX socket structure...
           */
          memset(&so, 0, sizeof(so));
  
          const int s = splnet();
  
          sysctl_teardown(&ifp->if_sysctl_log);
  
          IFNET_LOCK(ifp);
  
          /*
           * Unset all queued link states and pretend a
           * link state change is scheduled.
           * This stops any more link state changes occurring for this
           * interface while it's being detached so it's safe
           * to drain the workqueue.
           */
          IF_LINK_STATE_CHANGE_LOCK(ifp);
          ifp->if_link_queue = -1; /* all bits set, see link_state_change() */
          ifp->if_link_scheduled = true;
          IF_LINK_STATE_CHANGE_UNLOCK(ifp);
          workqueue_wait(ifnet_link_state_wq, &ifp->if_link_work);
  
          if_deactivate(ifp);
          IFNET_UNLOCK(ifp);
  
          /*
           * Unlink from the list and wait for all readers to leave
           * from pserialize read sections.  Note that we can't do
           * psref_target_destroy here.  See below.
           */
          IFNET_GLOBAL_LOCK();
          ifindex2ifnet[ifp->if_index] = NULL;
          TAILQ_REMOVE(&ifnet_list, ifp, if_list);
          IFNET_WRITER_REMOVE(ifp);
          pserialize_perform(ifnet_psz);
          IFNET_GLOBAL_UNLOCK();
  
          if (ifp->if_slowtimo != NULL) {
                  struct if_slowtimo_data *isd = ifp->if_slowtimo_data;
  
                  mutex_enter(&isd->isd_lock);
                  isd->isd_dying = true;
                  mutex_exit(&isd->isd_lock);
                  callout_halt(&isd->isd_ch, NULL);
                  workqueue_wait(if_slowtimo_wq, &isd->isd_work);
                  callout_destroy(&isd->isd_ch);
                  mutex_destroy(&isd->isd_lock);
                  kmem_free(isd, sizeof(*isd));
  
                  ifp->if_slowtimo_data = NULL; /* paraonia */
                  ifp->if_slowtimo = NULL;      /* paranoia */
          }
          if_deferred_start_destroy(ifp);
  
          /*
           * Do an if_down() to give protocols a chance to do something.
           */
          if_down_deactivated(ifp);
  
  #ifdef ALTQ
          if (ALTQ_IS_ENABLED(&ifp->if_snd))
                  altq_disable(&ifp->if_snd);
          if (ALTQ_IS_ATTACHED(&ifp->if_snd))
                  altq_detach(&ifp->if_snd);
  #endif
  
  #if NCARP > 0
          /* Remove the interface from any carp group it is a part of.  */
          if (ifp->if_carp != NULL && ifp->if_type != IFT_CARP)
                  carp_ifdetach(ifp);
  #endif
  
          /*
           * Ensure that all packets on protocol input pktqueues have been
           * processed, or, at least, removed from the queues.
           *
           * A cross-call will ensure that the interrupts have completed.
           * FIXME: not quite..
           */
          pktq_ifdetach();
          xc_barrier(0);
  
          /*
           * Rip all the addresses off the interface.  This should make
           * all of the routes go away.
           *
           * pr_usrreq calls can remove an arbitrary number of ifaddrs
           * from the list, including our "cursor", ifa.  For safety,
           * and to honor the TAILQ abstraction, I just restart the
           * loop after each removal.  Note that the loop will exit
           * when all of the remaining ifaddrs belong to the AF_LINK
           * family.  I am counting on the historical fact that at
           * least one pr_usrreq in each address domain removes at
           * least one ifaddr.
           */
  again:
          /*
           * At this point, no other one tries to remove ifa in the list,
           * so we don't need to take a lock or psref.  Avoid using
           * IFADDR_READER_FOREACH to pass over an inspection of contract
           * violations of pserialize.
           */
          IFADDR_WRITER_FOREACH(ifa, ifp) {
                  family = ifa->ifa_addr->sa_family;
  #ifdef IFAREF_DEBUG
                  printf("if_detach: ifaddr %p, family %d, refcnt %d\n",
                      ifa, family, ifa->ifa_refcnt);
                  if (last_ifa != NULL && ifa == last_ifa)
                          panic("if_detach: loop detected");
                  last_ifa = ifa;
  #endif
                  if (family == AF_LINK)
                          continue;
                  dp = pffinddomain(family);
                  KASSERTMSG(dp != NULL, "no domain for AF %d", family);
                  /*
                   * XXX These PURGEIF calls are redundant with the
                   * purge-all-families calls below, but are left in for
                   * now both to make a smaller change, and to avoid
                   * unplanned interactions with clearing of
                   * ifp->if_addrlist.
                   */
                  purged = 0;
                  for (pr = dp->dom_protosw;
                       pr < dp->dom_protoswNPROTOSW; pr++) {
                          so.so_proto = pr;
                          if (pr->pr_usrreqs) {
                                  (void) (*pr->pr_usrreqs->pr_purgeif)(&so, ifp);
                                  purged = 1;
                          }
                  }
                  if (purged == 0) {
                          /*
                           * XXX What's really the best thing to do
                           * XXX here?  --thorpej@NetBSD.org
                           */
                          printf("if_detach: WARNING: AF %d not purged\n",
                              family);
                          ifa_remove(ifp, ifa);
                  }
                  goto again;
          }
  
          if_free_sadl(ifp, 1);
  
  restart:
          IFADDR_WRITER_FOREACH(ifa, ifp) {
                  family = ifa->ifa_addr->sa_family;
                  KASSERT(family == AF_LINK);
                  ifa_remove(ifp, ifa);
                  goto restart;
          }
  
          /* Delete stray routes from the routing table. */
          for (i = 0; i <= AF_MAX; i++)
                  rt_delete_matched_entries(i, if_delroute_matcher, ifp, false);
  
          DOMAIN_FOREACH(dp) {
                  if (dp->dom_ifdetach != NULL && ifp->if_afdata[dp->dom_family])
                  {
                          void *p = ifp->if_afdata[dp->dom_family];
                          if (p) {
                                  ifp->if_afdata[dp->dom_family] = NULL;
                                  (*dp->dom_ifdetach)(ifp, p);
                          }
                  }
  
                  /*
                   * One would expect multicast memberships (INET and
                   * INET6) on UDP sockets to be purged by the PURGEIF
                   * calls above, but if all addresses were removed from
                   * the interface prior to destruction, the calls will
                   * not be made (e.g. ppp, for which pppd(8) generally
                   * removes addresses before destroying the interface).
                   * Because there is no invariant that multicast
                   * memberships only exist for interfaces with IPv4
                   * addresses, we must call PURGEIF regardless of
                   * addresses.  (Protocols which might store ifnet
                   * pointers are marked with PR_PURGEIF.)
                   */
                  for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++)
                  {
                          so.so_proto = pr;
                          if (pr->pr_usrreqs && pr->pr_flags & PR_PURGEIF)
                                  (void)(*pr->pr_usrreqs->pr_purgeif)(&so, ifp);
                  }
          }
  
          /*
           * Must be done after the above pr_purgeif because if_psref may be
           * still used in pr_purgeif.
           */
          psref_target_destroy(&ifp->if_psref, ifnet_psref_class);
          PSLIST_ENTRY_DESTROY(ifp, if_pslist_entry);
  
          pfil_run_ifhooks(if_pfil, PFIL_IFNET_DETACH, ifp);
          (void)pfil_head_destroy(ifp->if_pfil);
  
          /* Announce that the interface is gone. */
          rt_ifannouncemsg(ifp, IFAN_DEPARTURE);
  
          IF_AFDATA_LOCK_DESTROY(ifp);
  
          if (ifp->if_percpuq != NULL) {
                  if_percpuq_destroy(ifp->if_percpuq);
                  ifp->if_percpuq = NULL;
          }
  
          mutex_obj_free(ifp->if_ioctl_lock);
          ifp->if_ioctl_lock = NULL;
          mutex_obj_free(ifp->if_snd.ifq_lock);
          if_stats_fini(ifp);
          KASSERT(!simplehook_has_hooks(ifp->if_linkstate_hooks));
          simplehook_destroy(ifp->if_linkstate_hooks);
  
          splx(s);
  
  #ifdef IFAREF_DEBUG
          if_check_and_free_ifa_list(ifp);
  #endif
  }
  
  /*
   * Callback for a radix tree walk to delete all references to an
   * ifnet.
   */
  static int
  if_delroute_matcher(struct rtentry *rt, void *v)
  {
          struct ifnet *ifp = (struct ifnet *)v;
  
          if (rt->rt_ifp == ifp)
                  return 1;
          else
                  return 0;
  }
  
  /*
   * Create a clone network interface.
   */
  static int
  if_clone_create(const char *name)
  {
          struct if_clone *ifc;
          struct ifnet *ifp;
          struct psref psref;
          int unit;
  
          KASSERT(mutex_owned(&if_clone_mtx));
  
          ifc = if_clone_lookup(name, &unit);
          if (ifc == NULL)
                  return EINVAL;
  
          ifp = if_get(name, &psref);
          if (ifp != NULL) {
                  if_put(ifp, &psref);
                  return EEXIST;
          }
  
          return (*ifc->ifc_create)(ifc, unit);
  }
  
  /*
   * Destroy a clone network interface.
   */
  static int
  if_clone_destroy(const char *name)
  {
          struct if_clone *ifc;
          struct ifnet *ifp;
          struct psref psref;
          int error;
          int (*if_ioctlfn)(struct ifnet *, u_long, void *);
  
          KASSERT(mutex_owned(&if_clone_mtx));
  
          ifc = if_clone_lookup(name, NULL);
          if (ifc == NULL)
                  return EINVAL;
  
          if (ifc->ifc_destroy == NULL)
                  return EOPNOTSUPP;
  
          ifp = if_get(name, &psref);
          if (ifp == NULL)
                  return ENXIO;
  
          /* We have to disable ioctls here */
          IFNET_LOCK(ifp);
          if_ioctlfn = ifp->if_ioctl;
          ifp->if_ioctl = if_nullioctl;
          IFNET_UNLOCK(ifp);
  
          /*
           * We cannot call ifc_destroy with holding ifp.
           * Releasing ifp here is safe thanks to if_clone_mtx.
           */
          if_put(ifp, &psref);
  
          error = (*ifc->ifc_destroy)(ifp);
  
          if (error != 0) {
                  /* We have to restore if_ioctl on error */
                  IFNET_LOCK(ifp);
                  ifp->if_ioctl = if_ioctlfn;
                  IFNET_UNLOCK(ifp);
          }
  
          return error;
  }
  
  static bool
  if_is_unit(const char *name)
  {
  
          while (*name != '\0') {
                  if (*name < '' || *name > '9')
                          return false;
                  name++;
          }
  
          return true;
  }
  
  /*
   * Look up a network interface cloner.
   */
  static struct if_clone *
  if_clone_lookup(const char *name, int *unitp)
  {
          struct if_clone *ifc;
          const char *cp;
          char *dp, ifname[IFNAMSIZ + 3];
          int unit;
  
          KASSERT(mutex_owned(&if_clone_mtx));
  
          strcpy(ifname, "if_");
          /* separate interface name from unit */
          /* TODO: search unit number from backward */
          for (dp = ifname + 3, cp = name; cp - name < IFNAMSIZ &&
              *cp && !if_is_unit(cp);)
                  *dp++ = *cp++;
  
          if (cp == name || cp - name == IFNAMSIZ || !*cp)
                  return NULL;    /* No name or unit number */
          *dp++ = '\0';
  
  again:
          LIST_FOREACH(ifc, &if_cloners, ifc_list) {
                  if (strcmp(ifname + 3, ifc->ifc_name) == 0)
                          break;
          }
  
          if (ifc == NULL) {
                  int error;
                  if (*ifname == '\0')
                          return NULL;
                  mutex_exit(&if_clone_mtx);
                  error = module_autoload(ifname, MODULE_CLASS_DRIVER);
                  mutex_enter(&if_clone_mtx);
                  if (error)
                          return NULL;
                  *ifname = '\0';
                  goto again;
          }
  
          unit = 0;
          while (cp - name < IFNAMSIZ && *cp) {
                  if (*cp < '' || *cp > '9' || unit >= INT_MAX / 10) {
                          /* Bogus unit number. */
                          return NULL;
                  }
                  unit = (unit * 10) + (*cp++ - '');
          }
  
          if (unitp != NULL)
                  *unitp = unit;
          return ifc;
  }
  
  /*
   * Register a network interface cloner.
   */
  void
  if_clone_attach(struct if_clone *ifc)
  {
  
          mutex_enter(&if_clone_mtx);
          LIST_INSERT_HEAD(&if_cloners, ifc, ifc_list);
          if_cloners_count++;
          mutex_exit(&if_clone_mtx);
  }
  
  /*
   * Unregister a network interface cloner.
   */
  void
  if_clone_detach(struct if_clone *ifc)
  {
  
          mutex_enter(&if_clone_mtx);
          LIST_REMOVE(ifc, ifc_list);
          if_cloners_count--;
          mutex_exit(&if_clone_mtx);
  }
  
  /*
   * Provide list of interface cloners to userspace.
   */
  int
  if_clone_list(int buf_count, char *buffer, int *total)
  {
          char outbuf[IFNAMSIZ], *dst;
          struct if_clone *ifc;
          int count, error = 0;
  
          mutex_enter(&if_clone_mtx);
          *total = if_cloners_count;
          if ((dst = buffer) == NULL) {
                  /* Just asking how many there are. */
                  goto out;
          }
  
          if (buf_count < 0) {
                  error = EINVAL;
                  goto out;
          }
  
          count = (if_cloners_count < buf_count) ? if_cloners_count : buf_count;
  
          for (ifc = LIST_FIRST(&if_cloners); ifc != NULL && count != 0;
               ifc = LIST_NEXT(ifc, ifc_list), count--, dst += IFNAMSIZ) {
                  (void)strncpy(outbuf, ifc->ifc_name, sizeof(outbuf));
                  if (outbuf[sizeof(outbuf) - 1] != '\0') {
                          error = ENAMETOOLONG;
                          goto out;
                  }
                  error = copyout(outbuf, dst, sizeof(outbuf));
                  if (error != 0)
                          break;
          }
  
  out:
          mutex_exit(&if_clone_mtx);
          return error;
  }
  
  void
  ifa_psref_init(struct ifaddr *ifa)
  {
  
          psref_target_init(&ifa->ifa_psref, ifa_psref_class);
  }
  
  void
  ifaref(struct ifaddr *ifa)
  {
  
          atomic_inc_uint(&ifa->ifa_refcnt);
  }
  
  void
  ifafree(struct ifaddr *ifa)
  {
          KASSERT(ifa != NULL);
          KASSERTMSG(ifa->ifa_refcnt > 0, "ifa_refcnt=%d", ifa->ifa_refcnt);
  
  #ifndef __HAVE_ATOMIC_AS_MEMBAR
          membar_release();
  #endif
          if (atomic_dec_uint_nv(&ifa->ifa_refcnt) != 0)
                  return;
  #ifndef __HAVE_ATOMIC_AS_MEMBAR
          membar_acquire();
  #endif
          free(ifa, M_IFADDR);
  }
  
  bool
  ifa_is_destroying(struct ifaddr *ifa)
  {
  
          return ISSET(ifa->ifa_flags, IFA_DESTROYING);
  }
  
  void
  ifa_insert(struct ifnet *ifp, struct ifaddr *ifa)
  {
  
          ifa->ifa_ifp = ifp;
  
          /*
           * Check MP-safety for IFEF_MPSAFE drivers.
           * Check !IFF_RUNNING for initialization routines that normally don't
           * take IFNET_LOCK but it's safe because there is no competitor.
           * XXX there are false positive cases because IFF_RUNNING can be off on
           * if_stop.
           */
          KASSERT(!if_is_mpsafe(ifp) || !ISSET(ifp->if_flags, IFF_RUNNING) ||
              IFNET_LOCKED(ifp));
  
          TAILQ_INSERT_TAIL(&ifp->if_addrlist, ifa, ifa_list);
          IFADDR_ENTRY_INIT(ifa);
          IFADDR_WRITER_INSERT_TAIL(ifp, ifa);
  
          ifaref(ifa);
  }
  
  void
  ifa_remove(struct ifnet *ifp, struct ifaddr *ifa)
  {
  
          KASSERT(ifa->ifa_ifp == ifp);
          /*
           * Check MP-safety for IFEF_MPSAFE drivers.
           * if_is_deactivated indicates ifa_remove is called from if_detach
           * where it is safe even if IFNET_LOCK isn't held.
           */
          KASSERT(!if_is_mpsafe(ifp) || if_is_deactivated(ifp) ||
              IFNET_LOCKED(ifp));
  
          TAILQ_REMOVE(&ifp->if_addrlist, ifa, ifa_list);
          IFADDR_WRITER_REMOVE(ifa);
  #ifdef NET_MPSAFE
          IFNET_GLOBAL_LOCK();
          pserialize_perform(ifnet_psz);
          IFNET_GLOBAL_UNLOCK();
  #endif
  
  #ifdef NET_MPSAFE
          psref_target_destroy(&ifa->ifa_psref, ifa_psref_class);
  #endif
          IFADDR_ENTRY_DESTROY(ifa);
          ifafree(ifa);
  }
  
  void
  ifa_acquire(struct ifaddr *ifa, struct psref *psref)
  {
  
          PSREF_DEBUG_FILL_RETURN_ADDRESS(psref);
          psref_acquire(psref, &ifa->ifa_psref, ifa_psref_class);
  }
  
  void
  ifa_release(struct ifaddr *ifa, struct psref *psref)
  {
  
          if (ifa == NULL)
                  return;
  
          psref_release(psref, &ifa->ifa_psref, ifa_psref_class);
  }
  
  bool
  ifa_held(struct ifaddr *ifa)
  {
  
          return psref_held(&ifa->ifa_psref, ifa_psref_class);
  }
  
  static inline int
  equal(const struct sockaddr *sa1, const struct sockaddr *sa2)
  {
  
          return sockaddr_cmp(sa1, sa2) == 0;
  }
  
  /*
   * Locate an interface based on a complete address.
   */
  /*ARGSUSED*/
  struct ifaddr *
  ifa_ifwithaddr(const struct sockaddr *addr)
  {
          struct ifnet *ifp;
          struct ifaddr *ifa;
  
          IFNET_READER_FOREACH(ifp) {
                  if (if_is_deactivated(ifp))
                          continue;
                  IFADDR_READER_FOREACH(ifa, ifp) {
                          if (ifa->ifa_addr->sa_family != addr->sa_family)
                                  continue;
                          if (equal(addr, ifa->ifa_addr))
                                  return ifa;
                          if ((ifp->if_flags & IFF_BROADCAST) &&
                              ifa->ifa_broadaddr &&
                              /* IP6 doesn't have broadcast */
                              ifa->ifa_broadaddr->sa_len != 0 &&
                              equal(ifa->ifa_broadaddr, addr))
                                  return ifa;
                  }
          }
          return NULL;
  }
  
  struct ifaddr *
  ifa_ifwithaddr_psref(const struct sockaddr *addr, struct psref *psref)
  {
          struct ifaddr *ifa;
          int s = pserialize_read_enter();
  
          ifa = ifa_ifwithaddr(addr);
          if (ifa != NULL)
                  ifa_acquire(ifa, psref);
          pserialize_read_exit(s);
  
          return ifa;
  }
  
  /*
   * Locate the point to point interface with a given destination address.
   */
  /*ARGSUSED*/
  struct ifaddr *
  ifa_ifwithdstaddr(const struct sockaddr *addr)
  {
          struct ifnet *ifp;
          struct ifaddr *ifa;
  
          IFNET_READER_FOREACH(ifp) {
                  if (if_is_deactivated(ifp))
                          continue;
                  if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
                          continue;
                  IFADDR_READER_FOREACH(ifa, ifp) {
                          if (ifa->ifa_addr->sa_family != addr->sa_family ||
                              ifa->ifa_dstaddr == NULL)
                                  continue;
                          if (equal(addr, ifa->ifa_dstaddr))
                                  return ifa;
                  }
          }
  
          return NULL;
  }
  
  struct ifaddr *
  ifa_ifwithdstaddr_psref(const struct sockaddr *addr, struct psref *psref)
  {
          struct ifaddr *ifa;
          int s;
  
          s = pserialize_read_enter();
          ifa = ifa_ifwithdstaddr(addr);
          if (ifa != NULL)
                  ifa_acquire(ifa, psref);
          pserialize_read_exit(s);
  
          return ifa;
  }
  
  /*
   * Find an interface on a specific network.  If many, choice
   * is most specific found.
   */
  struct ifaddr *
  ifa_ifwithnet(const struct sockaddr *addr)
  {
          struct ifnet *ifp;
          struct ifaddr *ifa, *ifa_maybe = NULL;
          const struct sockaddr_dl *sdl;
          u_int af = addr->sa_family;
          const char *addr_data = addr->sa_data, *cplim;
  
          if (af == AF_LINK) {
                  sdl = satocsdl(addr);
                  if (sdl->sdl_index && sdl->sdl_index < if_indexlim &&
                      ifindex2ifnet[sdl->sdl_index] &&
                      !if_is_deactivated(ifindex2ifnet[sdl->sdl_index])) {
                          return ifindex2ifnet[sdl->sdl_index]->if_dl;
                  }
          }
  #ifdef NETATALK
          if (af == AF_APPLETALK) {
                  const struct sockaddr_at *sat, *sat2;
                  sat = (const struct sockaddr_at *)addr;
                  IFNET_READER_FOREACH(ifp) {
                          if (if_is_deactivated(ifp))
                                  continue;
                          ifa = at_ifawithnet((const struct sockaddr_at *)addr,
                              ifp);
                          if (ifa == NULL)
                                  continue;
                          sat2 = (struct sockaddr_at *)ifa->ifa_addr;
                          if (sat2->sat_addr.s_net == sat->sat_addr.s_net)
                                  return ifa; /* exact match */
                          if (ifa_maybe == NULL) {
                                  /* else keep the if with the right range */
                                  ifa_maybe = ifa;
                          }
                  }
                  return ifa_maybe;
          }
  #endif
          IFNET_READER_FOREACH(ifp) {
                  if (if_is_deactivated(ifp))
                          continue;
                  IFADDR_READER_FOREACH(ifa, ifp) {
                          const char *cp, *cp2, *cp3;
  
                          if (ifa->ifa_addr->sa_family != af ||
                              ifa->ifa_netmask == NULL)
   next:                          continue;
                          cp = addr_data;
                          cp2 = ifa->ifa_addr->sa_data;
                          cp3 = ifa->ifa_netmask->sa_data;
                          cplim = (const char *)ifa->ifa_netmask +
                              ifa->ifa_netmask->sa_len;
                          while (cp3 < cplim) {
                                  if ((*cp++ ^ *cp2++) & *cp3++) {
                                          /* want to continue for() loop */
                                          goto next;
                                  }
                          }
                          if (ifa_maybe == NULL ||
                              rt_refines(ifa->ifa_netmask,
                                         ifa_maybe->ifa_netmask))
                                  ifa_maybe = ifa;
                  }
          }
          return ifa_maybe;
  }
  
  struct ifaddr *
  ifa_ifwithnet_psref(const struct sockaddr *addr, struct psref *psref)
  {
          struct ifaddr *ifa;
          int s;
  
          s = pserialize_read_enter();
          ifa = ifa_ifwithnet(addr);
          if (ifa != NULL)
                  ifa_acquire(ifa, psref);
          pserialize_read_exit(s);
  
          return ifa;
  }
  
  /*
   * Find the interface of the address.
   */
  struct ifaddr *
  ifa_ifwithladdr(const struct sockaddr *addr)
  {
          struct ifaddr *ia;
  
          if ((ia = ifa_ifwithaddr(addr)) || (ia = ifa_ifwithdstaddr(addr)) ||
              (ia = ifa_ifwithnet(addr)))
                  return ia;
          return NULL;
  }
  
  struct ifaddr *
  ifa_ifwithladdr_psref(const struct sockaddr *addr, struct psref *psref)
  {
          struct ifaddr *ifa;
          int s;
  
          s = pserialize_read_enter();
          ifa = ifa_ifwithladdr(addr);
          if (ifa != NULL)
                  ifa_acquire(ifa, psref);
          pserialize_read_exit(s);
  
          return ifa;
  }
  
  /*
   * Find an interface using a specific address family
   */
  struct ifaddr *
  ifa_ifwithaf(int af)
  {
          struct ifnet *ifp;
          struct ifaddr *ifa = NULL;
          int s;
  
          s = pserialize_read_enter();
          IFNET_READER_FOREACH(ifp) {
                  if (if_is_deactivated(ifp))
                          continue;
                  IFADDR_READER_FOREACH(ifa, ifp) {
                          if (ifa->ifa_addr->sa_family == af)
                                  goto out;
                  }
          }
  out:
          pserialize_read_exit(s);
          return ifa;
  }
  
  /*
   * Find an interface address specific to an interface best matching
   * a given address.
   */
  struct ifaddr *
  ifaof_ifpforaddr(const struct sockaddr *addr, struct ifnet *ifp)
  {
          struct ifaddr *ifa;
          const char *cp, *cp2, *cp3;
          const char *cplim;
          struct ifaddr *ifa_maybe = 0;
          u_int af = addr->sa_family;
  
          if (if_is_deactivated(ifp))
                  return NULL;
  
          if (af >= AF_MAX)
                  return NULL;
  
          IFADDR_READER_FOREACH(ifa, ifp) {
                  if (ifa->ifa_addr->sa_family != af)
                          continue;
                  ifa_maybe = ifa;
                  if (ifa->ifa_netmask == NULL) {
                          if (equal(addr, ifa->ifa_addr) ||
                              (ifa->ifa_dstaddr &&
                               equal(addr, ifa->ifa_dstaddr)))
                                  return ifa;
                          continue;
                  }
                  cp = addr->sa_data;
                  cp2 = ifa->ifa_addr->sa_data;
                  cp3 = ifa->ifa_netmask->sa_data;
                  cplim = ifa->ifa_netmask->sa_len + (char *)ifa->ifa_netmask;
                  for (; cp3 < cplim; cp3++) {
                          if ((*cp++ ^ *cp2++) & *cp3)
                                  break;
                  }
                  if (cp3 == cplim)
                          return ifa;
          }
          return ifa_maybe;
  }
  
  struct ifaddr *
  ifaof_ifpforaddr_psref(const struct sockaddr *addr, struct ifnet *ifp,
      struct psref *psref)
  {
          struct ifaddr *ifa;
          int s;
  
          s = pserialize_read_enter();
          ifa = ifaof_ifpforaddr(addr, ifp);
          if (ifa != NULL)
                  ifa_acquire(ifa, psref);
          pserialize_read_exit(s);
  
          return ifa;
  }
  
  /*
   * Default action when installing a route with a Link Level gateway.
   * Lookup an appropriate real ifa to point to.
   * This should be moved to /sys/net/link.c eventually.
   */
  void
  link_rtrequest(int cmd, struct rtentry *rt, const struct rt_addrinfo *info)
  {
          struct ifaddr *ifa;
          const struct sockaddr *dst;
          struct ifnet *ifp;
          struct psref psref;
  
          if (cmd != RTM_ADD || ISSET(info->rti_flags, RTF_DONTCHANGEIFA))
                  return;
          ifp = rt->rt_ifa->ifa_ifp;
          dst = rt_getkey(rt);
          if ((ifa = ifaof_ifpforaddr_psref(dst, ifp, &psref)) != NULL) {
                  rt_replace_ifa(rt, ifa);
                  if (ifa->ifa_rtrequest && ifa->ifa_rtrequest != link_rtrequest)
                          ifa->ifa_rtrequest(cmd, rt, info);
                  ifa_release(ifa, &psref);
          }
  }
  
  /*
   * bitmask macros to manage a densely packed link_state change queue.
   * Because we need to store LINK_STATE_UNKNOWN(0), LINK_STATE_DOWN(1) and
   * LINK_STATE_UP(2) we need 2 bits for each state change.
   * As a state change to store is 0, treat all bits set as an unset item.
   */
  #define LQ_ITEM_BITS            2
  #define LQ_ITEM_MASK            ((1 << LQ_ITEM_BITS) - 1)
  #define LQ_MASK(i)              (LQ_ITEM_MASK << (i) * LQ_ITEM_BITS)
  #define LINK_STATE_UNSET        LQ_ITEM_MASK
  #define LQ_ITEM(q, i)           (((q) & LQ_MASK((i))) >> (i) * LQ_ITEM_BITS)
  #define LQ_STORE(q, i, v)                                                     \
          do {                                                                  \
                  (q) &= ~LQ_MASK((i));                                         \
                  (q) |= (v) << (i) * LQ_ITEM_BITS;                             \
          } while (0 /* CONSTCOND */)
  #define LQ_MAX(q)               ((sizeof((q)) * NBBY) / LQ_ITEM_BITS)
  #define LQ_POP(q, v)                                                          \
          do {                                                                  \
                  (v) = LQ_ITEM((q), 0);                                        \
                  (q) >>= LQ_ITEM_BITS;                                         \
                  (q) |= LINK_STATE_UNSET << (LQ_MAX((q)) - 1) * LQ_ITEM_BITS;  \
          } while (0 /* CONSTCOND */)
  #define LQ_PUSH(q, v)                                                         \
          do {                                                                  \
                  (q) >>= LQ_ITEM_BITS;                                         \
                  (q) |= (v) << (LQ_MAX((q)) - 1) * LQ_ITEM_BITS;               \
          } while (0 /* CONSTCOND */)
  #define LQ_FIND_UNSET(q, i)                                                   \
          for ((i) = 0; i < LQ_MAX((q)); (i)++) {                               \
                  if (LQ_ITEM((q), (i)) == LINK_STATE_UNSET)                    \
                          break;                                                \
          }
  
  /*
   * Handle a change in the interface link state and
   * queue notifications.
   */
  void
  if_link_state_change(struct ifnet *ifp, int link_state)
  {
          int idx;
  
          /* Ensure change is to a valid state */
          switch (link_state) {
          case LINK_STATE_UNKNOWN:        /* FALLTHROUGH */
          case LINK_STATE_DOWN:           /* FALLTHROUGH */
          case LINK_STATE_UP:
                  break;
          default:
  #ifdef DEBUG
                  printf("%s: invalid link state %d\n",
                      ifp->if_xname, link_state);
  #endif
                  return;
          }
  
          IF_LINK_STATE_CHANGE_LOCK(ifp);
  
          /* Find the last unset event in the queue. */
          LQ_FIND_UNSET(ifp->if_link_queue, idx);
  
          if (idx == 0) {
                  /*
                   * There is no queue of link state changes.
                   * As we have the lock we can safely compare against the
                   * current link state and return if the same.
                   * Otherwise, if scheduled is true then the interface is being
                   * detached and the queue is being drained so we need
                   * to avoid queuing more work.
                   */
                   if (ifp->if_link_state == link_state ||
                       ifp->if_link_scheduled)
                          goto out;
          } else {
                  /* Ensure link_state doesn't match the last queued state. */
                  if (LQ_ITEM(ifp->if_link_queue, idx - 1)
                      == (uint8_t)link_state)
                          goto out;
          }
  
          /* Handle queue overflow. */
          if (idx == LQ_MAX(ifp->if_link_queue)) {
                  uint8_t lost;
  
                  /*
                   * The DOWN state must be protected from being pushed off
                   * the queue to ensure that userland will always be
                   * in a sane state.
                   * Because DOWN is protected, there is no need to protect
                   * UNKNOWN.
                   * It should be invalid to change from any other state to
                   * UNKNOWN anyway ...
                   */
                  lost = LQ_ITEM(ifp->if_link_queue, 0);
                  LQ_PUSH(ifp->if_link_queue, (uint8_t)link_state);
                  if (lost == LINK_STATE_DOWN) {
                          lost = LQ_ITEM(ifp->if_link_queue, 0);
                          LQ_STORE(ifp->if_link_queue, 0, LINK_STATE_DOWN);
                  }
                  printf("%s: lost link state change %s\n",
                      ifp->if_xname,
                      lost == LINK_STATE_UP ? "UP" :
                      lost == LINK_STATE_DOWN ? "DOWN" :
                      "UNKNOWN");
          } else
                  LQ_STORE(ifp->if_link_queue, idx, (uint8_t)link_state);
  
          if (ifp->if_link_scheduled)
                  goto out;
  
          ifp->if_link_scheduled = true;
          workqueue_enqueue(ifnet_link_state_wq, &ifp->if_link_work, NULL);
  
  out:
          IF_LINK_STATE_CHANGE_UNLOCK(ifp);
  }
  
  /*
   * Handle interface link state change notifications.
   */
  static void
  if_link_state_change_process(struct ifnet *ifp, int link_state)
  {
          struct domain *dp;
          const int s = splnet();
          bool notify;
  
          KASSERT(!cpu_intr_p());
  
          IF_LINK_STATE_CHANGE_LOCK(ifp);
  
          /* Ensure the change is still valid. */
          if (ifp->if_link_state == link_state) {
                  IF_LINK_STATE_CHANGE_UNLOCK(ifp);
                  splx(s);
                  return;
          }
  
  #ifdef DEBUG
          log(LOG_DEBUG, "%s: link state %s (was %s)\n", ifp->if_xname,
                  link_state == LINK_STATE_UP ? "UP" :
                  link_state == LINK_STATE_DOWN ? "DOWN" :
                  "UNKNOWN",
                  ifp->if_link_state == LINK_STATE_UP ? "UP" :
                  ifp->if_link_state == LINK_STATE_DOWN ? "DOWN" :
                  "UNKNOWN");
  #endif
  
          /*
           * When going from UNKNOWN to UP, we need to mark existing
           * addresses as tentative and restart DAD as we may have
           * erroneously not found a duplicate.
           *
           * This needs to happen before rt_ifmsg to avoid a race where
           * listeners would have an address and expect it to work right
           * away.
           */
          notify = (link_state == LINK_STATE_UP &&
              ifp->if_link_state == LINK_STATE_UNKNOWN);
          ifp->if_link_state = link_state;
          /* The following routines may sleep so release the spin mutex */
          IF_LINK_STATE_CHANGE_UNLOCK(ifp);
  
          KERNEL_LOCK_UNLESS_NET_MPSAFE();
          if (notify) {
                  DOMAIN_FOREACH(dp) {
                          if (dp->dom_if_link_state_change != NULL)
                                  dp->dom_if_link_state_change(ifp,
                                      LINK_STATE_DOWN);
                  }
          }
  
          /* Notify that the link state has changed. */
          rt_ifmsg(ifp);
  
          simplehook_dohooks(ifp->if_linkstate_hooks);
  
          DOMAIN_FOREACH(dp) {
                  if (dp->dom_if_link_state_change != NULL)
                          dp->dom_if_link_state_change(ifp, link_state);
          }
          KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
          splx(s);
  }
  
  /*
   * Process the interface link state change queue.
   */
  static void
  if_link_state_change_work(struct work *work, void *arg)
  {
          struct ifnet *ifp = container_of(work, struct ifnet, if_link_work);
          uint8_t state;
  
          KERNEL_LOCK_UNLESS_NET_MPSAFE();
          const int s = splnet();
  
          /*
           * Pop a link state change from the queue and process it.
           * If there is nothing to process then if_detach() has been called.
           * We keep if_link_scheduled = true so the queue can safely drain
           * without more work being queued.
           */
          IF_LINK_STATE_CHANGE_LOCK(ifp);
          LQ_POP(ifp->if_link_queue, state);
          IF_LINK_STATE_CHANGE_UNLOCK(ifp);
          if (state == LINK_STATE_UNSET)
                  goto out;
  
          if_link_state_change_process(ifp, state);
  
          /* If there is a link state change to come, schedule it. */
          IF_LINK_STATE_CHANGE_LOCK(ifp);
          if (LQ_ITEM(ifp->if_link_queue, 0) != LINK_STATE_UNSET) {
                  ifp->if_link_scheduled = true;
                  workqueue_enqueue(ifnet_link_state_wq, &ifp->if_link_work,
                      NULL);
          } else
                  ifp->if_link_scheduled = false;
          IF_LINK_STATE_CHANGE_UNLOCK(ifp);
  
  out:
          splx(s);
          KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
  }
  
  void *
  if_linkstate_change_establish(struct ifnet *ifp, void (*fn)(void *), void *arg)
  {
          khook_t *hk;
  
          hk = simplehook_establish(ifp->if_linkstate_hooks, fn, arg);
  
          return (void *)hk;
  }
  
  void
  if_linkstate_change_disestablish(struct ifnet *ifp, void *vhook,
      kmutex_t *lock)
  {
  
          simplehook_disestablish(ifp->if_linkstate_hooks, vhook, lock);
  }
  
  /*
   * Used to mark addresses on an interface as DETATCHED or TENTATIVE
   * and thus start Duplicate Address Detection without changing the
   * real link state.
   */
  void
  if_domain_link_state_change(struct ifnet *ifp, int link_state)
  {
          struct domain *dp;
  
          const int s = splnet();
          KERNEL_LOCK_UNLESS_NET_MPSAFE();
  
          DOMAIN_FOREACH(dp) {
                  if (dp->dom_if_link_state_change != NULL)
                          dp->dom_if_link_state_change(ifp, link_state);
          }
  
          splx(s);
          KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
  }
  
  /*
   * Default action when installing a local route on a point-to-point
   * interface.
   */
  void
  p2p_rtrequest(int req, struct rtentry *rt,
      __unused const struct rt_addrinfo *info)
  {
          struct ifnet *ifp = rt->rt_ifp;
          struct ifaddr *ifa, *lo0ifa;
          int s = pserialize_read_enter();
  
          switch (req) {
          case RTM_ADD:
                  if ((rt->rt_flags & RTF_LOCAL) == 0)
                          break;
  
                  rt->rt_ifp = lo0ifp;
  
                  if (ISSET(info->rti_flags, RTF_DONTCHANGEIFA))
                          break;
  
                  IFADDR_READER_FOREACH(ifa, ifp) {
                          if (equal(rt_getkey(rt), ifa->ifa_addr))
                                  break;
                  }
                  if (ifa == NULL)
                          break;
  
                  /*
                   * Ensure lo0 has an address of the same family.
                   */
                  IFADDR_READER_FOREACH(lo0ifa, lo0ifp) {
                          if (lo0ifa->ifa_addr->sa_family ==
                              ifa->ifa_addr->sa_family)
                                  break;
                  }
                  if (lo0ifa == NULL)
                          break;
  
                  /*
                   * Make sure to set rt->rt_ifa to the interface
                   * address we are using, otherwise we will have trouble
                   * with source address selection.
                   */
                  if (ifa != rt->rt_ifa)
                          rt_replace_ifa(rt, ifa);
                  break;
          case RTM_DELETE:
          default:
                  break;
          }
          pserialize_read_exit(s);
  }
  
  static void
  _if_down(struct ifnet *ifp)
  {
          struct ifaddr *ifa;
          struct domain *dp;
          struct psref psref;
  
          ifp->if_flags &= ~IFF_UP;
          nanotime(&ifp->if_lastchange);
  
          const int bound = curlwp_bind();
          int s = pserialize_read_enter();
          IFADDR_READER_FOREACH(ifa, ifp) {
                  ifa_acquire(ifa, &psref);
                  pserialize_read_exit(s);
  
                  pfctlinput(PRC_IFDOWN, ifa->ifa_addr);
  
                  s = pserialize_read_enter();
                  ifa_release(ifa, &psref);
          }
          pserialize_read_exit(s);
          curlwp_bindx(bound);
  
          IFQ_PURGE(&ifp->if_snd);
  #if NCARP > 0
          if (ifp->if_carp)
                  carp_carpdev_state(ifp);
  #endif
          rt_ifmsg(ifp);
          DOMAIN_FOREACH(dp) {
                  if (dp->dom_if_down)
                          dp->dom_if_down(ifp);
          }
  }
  
  static void
  if_down_deactivated(struct ifnet *ifp)
  {
  
          KASSERT(if_is_deactivated(ifp));
          _if_down(ifp);
  }
  
  void
  if_down_locked(struct ifnet *ifp)
  {
  
          KASSERT(IFNET_LOCKED(ifp));
          _if_down(ifp);
  }
  
  /*
   * Mark an interface down and notify protocols of
   * the transition.
   * NOTE: must be called at splsoftnet or equivalent.
   */
  void
  if_down(struct ifnet *ifp)
  {
  
          IFNET_LOCK(ifp);
          if_down_locked(ifp);
          IFNET_UNLOCK(ifp);
  }
  
  /*
   * Must be called with holding if_ioctl_lock.
   */
  static void
  if_up_locked(struct ifnet *ifp)
  {
  #ifdef notyet
          struct ifaddr *ifa;
  #endif
          struct domain *dp;
  
          KASSERT(IFNET_LOCKED(ifp));
  
          KASSERT(!if_is_deactivated(ifp));
          ifp->if_flags |= IFF_UP;
          nanotime(&ifp->if_lastchange);
  #ifdef notyet
          /* this has no effect on IP, and will kill all ISO connections XXX */
          IFADDR_READER_FOREACH(ifa, ifp)
                  pfctlinput(PRC_IFUP, ifa->ifa_addr);
  #endif
  #if NCARP > 0
          if (ifp->if_carp)
                  carp_carpdev_state(ifp);
  #endif
          rt_ifmsg(ifp);
          DOMAIN_FOREACH(dp) {
                  if (dp->dom_if_up)
                          dp->dom_if_up(ifp);
          }
  }
  
  /*
   * Handle interface slowtimo timer routine.  Called
   * from softclock, we decrement timer (if set) and
   * call the appropriate interface routine on expiration.
   */
  static bool
  if_slowtimo_countdown(struct ifnet *ifp)
  {
          bool fire = false;
          const int s = splnet();
  
          KERNEL_LOCK(1, NULL);
          if (ifp->if_timer != 0 && --ifp->if_timer == 0)
                  fire = true;
          KERNEL_UNLOCK_ONE(NULL);
          splx(s);
  
          return fire;
  }
  
  static void
  if_slowtimo_intr(void *arg)
  {
          struct ifnet *ifp = arg;
          struct if_slowtimo_data *isd = ifp->if_slowtimo_data;
  
          mutex_enter(&isd->isd_lock);
          if (!isd->isd_dying) {
                  if (isd->isd_trigger || if_slowtimo_countdown(ifp)) {
                          if (!isd->isd_queued) {
                                  isd->isd_queued = true;
                                  workqueue_enqueue(if_slowtimo_wq,
                                      &isd->isd_work, NULL);
                          }
                  } else
                          callout_schedule(&isd->isd_ch, hz / IFNET_SLOWHZ);
          }
          mutex_exit(&isd->isd_lock);
  }
  
  static void
  if_slowtimo_work(struct work *work, void *arg)
  {
          struct if_slowtimo_data *isd =
              container_of(work, struct if_slowtimo_data, isd_work);
          struct ifnet *ifp = isd->isd_ifp;
          const int s = splnet();
  
          KERNEL_LOCK(1, NULL);
          (*ifp->if_slowtimo)(ifp);
          KERNEL_UNLOCK_ONE(NULL);
          splx(s);
  
          mutex_enter(&isd->isd_lock);
          if (isd->isd_trigger) {
                  isd->isd_trigger = false;
                  printf("%s: watchdog triggered\n", ifp->if_xname);
          }
          isd->isd_queued = false;
          if (!isd->isd_dying)
                  callout_schedule(&isd->isd_ch, hz / IFNET_SLOWHZ);
          mutex_exit(&isd->isd_lock);
  }
  
  static int
  sysctl_if_watchdog(SYSCTLFN_ARGS)
  {
          struct sysctlnode node = *rnode;
          struct ifnet *ifp = node.sysctl_data;
          struct if_slowtimo_data *isd = ifp->if_slowtimo_data;
          int arg = 0;
          int error;
  
          node.sysctl_data = &arg;
          error = sysctl_lookup(SYSCTLFN_CALL(&node));
          if (error || newp == NULL)
                  return error;
          if (arg) {
                  mutex_enter(&isd->isd_lock);
                  KASSERT(!isd->isd_dying);
                  isd->isd_trigger = true;
                  callout_schedule(&isd->isd_ch, 0);
                  mutex_exit(&isd->isd_lock);
          }
  
          return 0;
  }
  
  static void
  sysctl_watchdog_setup(struct ifnet *ifp)
  {
          struct sysctllog **clog = &ifp->if_sysctl_log;
          const struct sysctlnode *rnode;
  
          if (sysctl_createv(clog, 0, NULL, &rnode,
                  CTLFLAG_PERMANENT, CTLTYPE_NODE, "interfaces",
                  SYSCTL_DESCR("Per-interface controls"),
                  NULL, 0, NULL, 0,
                  CTL_NET, CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
          if (sysctl_createv(clog, 0, &rnode, &rnode,
                  CTLFLAG_PERMANENT, CTLTYPE_NODE, ifp->if_xname,
                  SYSCTL_DESCR("Interface controls"),
                  NULL, 0, NULL, 0,
                  CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
          if (sysctl_createv(clog, 0, &rnode, &rnode,
                  CTLFLAG_PERMANENT, CTLTYPE_NODE, "watchdog",
                  SYSCTL_DESCR("Interface watchdog controls"),
                  NULL, 0, NULL, 0,
                  CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
          if (sysctl_createv(clog, 0, &rnode, NULL,
                  CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_INT, "trigger",
                  SYSCTL_DESCR("Trigger watchdog timeout"),
                  sysctl_if_watchdog, 0, (int *)ifp, 0,
                  CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
  
          return;
  
  bad:
          printf("%s: could not attach sysctl watchdog nodes\n", ifp->if_xname);
  }
  
  /*
   * Mark an interface up and notify protocols of
   * the transition.
   * NOTE: must be called at splsoftnet or equivalent.
   */
  void
  if_up(struct ifnet *ifp)
  {
  
          IFNET_LOCK(ifp);
          if_up_locked(ifp);
          IFNET_UNLOCK(ifp);
  }
  
  /*
   * Set/clear promiscuous mode on interface ifp based on the truth value
   * of pswitch.  The calls are reference counted so that only the first
   * "on" request actually has an effect, as does the final "off" request.
   * Results are undefined if the "off" and "on" requests are not matched.
   */
  int
  ifpromisc_locked(struct ifnet *ifp, int pswitch)
  {
          int pcount, ret = 0;
          u_short nflags;
  
          KASSERT(IFNET_LOCKED(ifp));
  
          pcount = ifp->if_pcount;
          if (pswitch) {
                  /*
                   * Allow the device to be "placed" into promiscuous
                   * mode even if it is not configured up.  It will
                   * consult IFF_PROMISC when it is brought up.
                   */
                  if (ifp->if_pcount++ != 0)
                          goto out;
                  nflags = ifp->if_flags | IFF_PROMISC;
          } else {
                  if (--ifp->if_pcount > 0)
                          goto out;
                  nflags = ifp->if_flags & ~IFF_PROMISC;
          }
          ret = if_flags_set(ifp, nflags);
          /* Restore interface state if not successful. */
          if (ret != 0)
                  ifp->if_pcount = pcount;
  
  out:
          return ret;
  }
  
  int
  ifpromisc(struct ifnet *ifp, int pswitch)
  {
          int e;
  
          IFNET_LOCK(ifp);
          e = ifpromisc_locked(ifp, pswitch);
          IFNET_UNLOCK(ifp);
  
          return e;
  }
  
  /*
   * if_ioctl(ifp, cmd, data)
   *
   *      Apply an ioctl command to the interface.  Returns 0 on success,
   *      nonzero errno(3) number on failure.
   *
   *      For SIOCADDMULTI/SIOCDELMULTI, caller need not hold locks -- it
   *      is the driver's responsibility to take any internal locks.
   *      (Kernel logic should generally invoke these only through
   *      if_mcast_op.)
   *
   *      For all other ioctls, caller must hold ifp->if_ioctl_lock,
   *      a.k.a. IFNET_LOCK.  May sleep.
   */
  int
  if_ioctl(struct ifnet *ifp, u_long cmd, void *data)
  {
  
          switch (cmd) {
          case SIOCADDMULTI:
          case SIOCDELMULTI:
                  break;
          default:
                  KASSERTMSG(IFNET_LOCKED(ifp), "%s", ifp->if_xname);
          }
  
          return (*ifp->if_ioctl)(ifp, cmd, data);
  }
  
  /*
   * if_init(ifp)
   *
   *      Prepare the hardware underlying ifp to process packets
   *      according to its current configuration.  Returns 0 on success,
   *      nonzero errno(3) number on failure.
   *
   *      May sleep.  Caller must hold ifp->if_ioctl_lock, a.k.a
   *      IFNET_LOCK.
   */
  int
  if_init(struct ifnet *ifp)
  {
  
          KASSERTMSG(IFNET_LOCKED(ifp), "%s", ifp->if_xname);
  
          return (*ifp->if_init)(ifp);
  }
  
  /*
   * if_stop(ifp, disable)
   *
   *      Stop the hardware underlying ifp from processing packets.
   *
   *      If disable is true, ... XXX(?)
   *
   *      May sleep.  Caller must hold ifp->if_ioctl_lock, a.k.a
   *      IFNET_LOCK.
   */
  void
  if_stop(struct ifnet *ifp, int disable)
  {
  
          KASSERTMSG(IFNET_LOCKED(ifp), "%s", ifp->if_xname);
  
          (*ifp->if_stop)(ifp, disable);
  }
  
  /*
   * Map interface name to
   * interface structure pointer.
   */
  struct ifnet *
  ifunit(const char *name)
  {
          struct ifnet *ifp;
          const char *cp = name;
          u_int unit = 0;
          u_int i;
  
          /*
           * If the entire name is a number, treat it as an ifindex.
           */
          for (i = 0; i < IFNAMSIZ && *cp >= '' && *cp <= '9'; i++, cp++)
                  unit = unit * 10 + (*cp - '');
  
          /*
           * If the number took all of the name, then it's a valid ifindex.
           */
          if (i == IFNAMSIZ || (cp != name && *cp == '\0'))
                  return if_byindex(unit);
  
          ifp = NULL;
          const int s = pserialize_read_enter();
          IFNET_READER_FOREACH(ifp) {
                  if (if_is_deactivated(ifp))
                          continue;
                  if (strcmp(ifp->if_xname, name) == 0)
                          goto out;
          }
  out:
          pserialize_read_exit(s);
          return ifp;
  }
  
  /*
   * Get a reference of an ifnet object by an interface name.
   * The returned reference is protected by psref(9). The caller
   * must release a returned reference by if_put after use.
   */
  struct ifnet *
  if_get(const char *name, struct psref *psref)
  {
          struct ifnet *ifp;
          const char *cp = name;
          u_int unit = 0;
          u_int i;
  
          /*
           * If the entire name is a number, treat it as an ifindex.
           */
          for (i = 0; i < IFNAMSIZ && *cp >= '' && *cp <= '9'; i++, cp++)
                  unit = unit * 10 + (*cp - '');
  
          /*
           * If the number took all of the name, then it's a valid ifindex.
           */
          if (i == IFNAMSIZ || (cp != name && *cp == '\0'))
                  return if_get_byindex(unit, psref);
  
          ifp = NULL;
          const int s = pserialize_read_enter();
          IFNET_READER_FOREACH(ifp) {
                  if (if_is_deactivated(ifp))
                          continue;
                  if (strcmp(ifp->if_xname, name) == 0) {
                          PSREF_DEBUG_FILL_RETURN_ADDRESS(psref);
                          psref_acquire(psref, &ifp->if_psref,
                              ifnet_psref_class);
                          goto out;
                  }
          }
  out:
          pserialize_read_exit(s);
          return ifp;
  }
  
  /*
   * Release a reference of an ifnet object given by if_get, if_get_byindex
   * or if_get_bylla.
   */
  void
  if_put(const struct ifnet *ifp, struct psref *psref)
  {
  
          if (ifp == NULL)
                  return;
  
          psref_release(psref, &ifp->if_psref, ifnet_psref_class);
  }
  
  /*
   * Return ifp having idx. Return NULL if not found.  Normally if_byindex
   * should be used.
   */
  ifnet_t *
  _if_byindex(u_int idx)
  {
  
          return (__predict_true(idx < if_indexlim)) ? ifindex2ifnet[idx] : NULL;
  }
  
  /*
   * Return ifp having idx. Return NULL if not found or the found ifp is
   * already deactivated.
   */
  ifnet_t *
  if_byindex(u_int idx)
  {
          ifnet_t *ifp;
  
          ifp = _if_byindex(idx);
          if (ifp != NULL && if_is_deactivated(ifp))
                  ifp = NULL;
          return ifp;
  }
  
  /*
   * Get a reference of an ifnet object by an interface index.
   * The returned reference is protected by psref(9). The caller
   * must release a returned reference by if_put after use.
   */
  ifnet_t *
  if_get_byindex(u_int idx, struct psref *psref)
  {
          ifnet_t *ifp;
  
          const int s = pserialize_read_enter();
          ifp = if_byindex(idx);
          if (__predict_true(ifp != NULL)) {
                  PSREF_DEBUG_FILL_RETURN_ADDRESS(psref);
                  psref_acquire(psref, &ifp->if_psref, ifnet_psref_class);
          }
          pserialize_read_exit(s);
  
          return ifp;
  }
  
  ifnet_t *
  if_get_bylla(const void *lla, unsigned char lla_len, struct psref *psref)
  {
          ifnet_t *ifp;
  
          const int s = pserialize_read_enter();
          IFNET_READER_FOREACH(ifp) {
                  if (if_is_deactivated(ifp))
                          continue;
                  if (ifp->if_addrlen != lla_len)
                          continue;
                  if (memcmp(lla, CLLADDR(ifp->if_sadl), lla_len) == 0) {
                          psref_acquire(psref, &ifp->if_psref,
                              ifnet_psref_class);
                          break;
                  }
          }
          pserialize_read_exit(s);
  
          return ifp;
  }
  
  /*
   * Note that it's safe only if the passed ifp is guaranteed to not be freed,
   * for example using pserialize or the ifp is already held or some other
   * object is held which guarantes the ifp to not be freed indirectly.
   */
  void
  if_acquire(struct ifnet *ifp, struct psref *psref)
  {
  
          KASSERT(ifp->if_index != 0);
          psref_acquire(psref, &ifp->if_psref, ifnet_psref_class);
  }
  
  bool
  if_held(struct ifnet *ifp)
  {
  
          return psref_held(&ifp->if_psref, ifnet_psref_class);
  }
  
  /*
   * Some tunnel interfaces can nest, e.g. IPv4 over IPv4 gif(4) tunnel over
   * IPv4. Check the tunnel nesting count.
   * Return > 0, if tunnel nesting count is more than limit.
   * Return 0, if tunnel nesting count is equal or less than limit.
   */
  int
  if_tunnel_check_nesting(struct ifnet *ifp, struct mbuf *m, int limit)
  {
          struct m_tag *mtag;
          int *count;
  
          mtag = m_tag_find(m, PACKET_TAG_TUNNEL_INFO);
          if (mtag != NULL) {
                  count = (int *)(mtag + 1);
                  if (++(*count) > limit) {
                          log(LOG_NOTICE,
                              "%s: recursively called too many times(%d)\n",
                              ifp->if_xname, *count);
                          return EIO;
                  }
          } else {
                  mtag = m_tag_get(PACKET_TAG_TUNNEL_INFO, sizeof(*count),
                      M_NOWAIT);
                  if (mtag != NULL) {
                          m_tag_prepend(m, mtag);
                          count = (int *)(mtag + 1);
                          *count = 0;
                  } else {
                          log(LOG_DEBUG, "%s: m_tag_get() failed, "
                              "recursion calls are not prevented.\n",
                              ifp->if_xname);
                  }
          }
  
          return 0;
  }
  
  static void
  if_tunnel_ro_init_pc(void *p, void *arg __unused, struct cpu_info *ci __unused)
  {
          struct tunnel_ro *tro = p;
  
          tro->tr_ro = kmem_zalloc(sizeof(*tro->tr_ro), KM_SLEEP);
          tro->tr_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
  }
  
  static void
  if_tunnel_ro_fini_pc(void *p, void *arg __unused, struct cpu_info *ci __unused)
  {
          struct tunnel_ro *tro = p;
  
          rtcache_free(tro->tr_ro);
          kmem_free(tro->tr_ro, sizeof(*tro->tr_ro));
  
          mutex_obj_free(tro->tr_lock);
  }
  
  percpu_t *
  if_tunnel_alloc_ro_percpu(void)
  {
  
          return percpu_create(sizeof(struct tunnel_ro),
              if_tunnel_ro_init_pc, if_tunnel_ro_fini_pc, NULL);
  }
  
  void
  if_tunnel_free_ro_percpu(percpu_t *ro_percpu)
  {
  
          percpu_free(ro_percpu, sizeof(struct tunnel_ro));
  }
  
  
  static void
  if_tunnel_rtcache_free_pc(void *p, void *arg __unused,
      struct cpu_info *ci __unused)
  {
          struct tunnel_ro *tro = p;
  
          mutex_enter(tro->tr_lock);
          rtcache_free(tro->tr_ro);
          mutex_exit(tro->tr_lock);
  }
  
  void if_tunnel_ro_percpu_rtcache_free(percpu_t *ro_percpu)
  {
  
          percpu_foreach(ro_percpu, if_tunnel_rtcache_free_pc, NULL);
  }
  
  void
  if_export_if_data(ifnet_t * const ifp, struct if_data *ifi, bool zero_stats)
  {
  
          /* Collect the volatile stats first; this zeros *ifi. */
          if_stats_to_if_data(ifp, ifi, zero_stats);
  
          ifi->ifi_type = ifp->if_type;
          ifi->ifi_addrlen = ifp->if_addrlen;
          ifi->ifi_hdrlen = ifp->if_hdrlen;
          ifi->ifi_link_state = ifp->if_link_state;
          ifi->ifi_mtu = ifp->if_mtu;
          ifi->ifi_metric = ifp->if_metric;
          ifi->ifi_baudrate = ifp->if_baudrate;
          ifi->ifi_lastchange = ifp->if_lastchange;
  }
  
  /* common */
  int
  ifioctl_common(struct ifnet *ifp, u_long cmd, void *data)
  {
          struct ifreq *ifr;
          struct ifcapreq *ifcr;
          struct ifdatareq *ifdr;
          unsigned short flags;
          char *descr;
          int error;
  
          switch (cmd) {
          case SIOCSIFCAP:
                  ifcr = data;
                  if ((ifcr->ifcr_capenable & ~ifp->if_capabilities) != 0)
                          return EINVAL;
  
                  if (ifcr->ifcr_capenable == ifp->if_capenable)
                          return 0;
  
                  ifp->if_capenable = ifcr->ifcr_capenable;
  
                  /* Pre-compute the checksum flags mask. */
                  ifp->if_csum_flags_tx = 0;
                  ifp->if_csum_flags_rx = 0;
                  if (ifp->if_capenable & IFCAP_CSUM_IPv4_Tx)
                          ifp->if_csum_flags_tx |= M_CSUM_IPv4;
                  if (ifp->if_capenable & IFCAP_CSUM_IPv4_Rx)
                          ifp->if_csum_flags_rx |= M_CSUM_IPv4;
  
                  if (ifp->if_capenable & IFCAP_CSUM_TCPv4_Tx)
                          ifp->if_csum_flags_tx |= M_CSUM_TCPv4;
                  if (ifp->if_capenable & IFCAP_CSUM_TCPv4_Rx)
                          ifp->if_csum_flags_rx |= M_CSUM_TCPv4;
  
                  if (ifp->if_capenable & IFCAP_CSUM_UDPv4_Tx)
                          ifp->if_csum_flags_tx |= M_CSUM_UDPv4;
                  if (ifp->if_capenable & IFCAP_CSUM_UDPv4_Rx)
                          ifp->if_csum_flags_rx |= M_CSUM_UDPv4;
  
                  if (ifp->if_capenable & IFCAP_CSUM_TCPv6_Tx)
                          ifp->if_csum_flags_tx |= M_CSUM_TCPv6;
                  if (ifp->if_capenable & IFCAP_CSUM_TCPv6_Rx)
                          ifp->if_csum_flags_rx |= M_CSUM_TCPv6;
  
                  if (ifp->if_capenable & IFCAP_CSUM_UDPv6_Tx)
                          ifp->if_csum_flags_tx |= M_CSUM_UDPv6;
                  if (ifp->if_capenable & IFCAP_CSUM_UDPv6_Rx)
                          ifp->if_csum_flags_rx |= M_CSUM_UDPv6;
  
                  if (ifp->if_capenable & IFCAP_TSOv4)
                          ifp->if_csum_flags_tx |= M_CSUM_TSOv4;
                  if (ifp->if_capenable & IFCAP_TSOv6)
                          ifp->if_csum_flags_tx |= M_CSUM_TSOv6;
  
  #if NBRIDGE > 0
                  if (ifp->if_bridge != NULL)
                          bridge_calc_csum_flags(ifp->if_bridge);
  #endif
  
                  if (ifp->if_flags & IFF_UP)
                          return ENETRESET;
                  return 0;
          case SIOCSIFFLAGS:
                  ifr = data;
                  /*
                   * If if_is_mpsafe(ifp), KERNEL_LOCK isn't held here, but if_up
                   * and if_down aren't MP-safe yet, so we must hold the lock.
                   */
                  KERNEL_LOCK_IF_IFP_MPSAFE(ifp);
                  if (ifp->if_flags & IFF_UP && (ifr->ifr_flags & IFF_UP) == 0) {
                          const int s = splsoftnet();
                          if_down_locked(ifp);
                          splx(s);
                  }
                  if (ifr->ifr_flags & IFF_UP && (ifp->if_flags & IFF_UP) == 0) {
                          const int s = splsoftnet();
                          if_up_locked(ifp);
                          splx(s);
                  }
                  KERNEL_UNLOCK_IF_IFP_MPSAFE(ifp);
                  flags = (ifp->if_flags & IFF_CANTCHANGE) |
                      (ifr->ifr_flags &~ IFF_CANTCHANGE);
                  if (ifp->if_flags != flags) {
                          ifp->if_flags = flags;
                          /* Notify that the flags have changed. */
                          rt_ifmsg(ifp);
                  }
                  break;
          case SIOCGIFFLAGS:
                  ifr = data;
                  ifr->ifr_flags = ifp->if_flags;
                  break;
  
          case SIOCGIFMETRIC:
                  ifr = data;
                  ifr->ifr_metric = ifp->if_metric;
                  break;
  
          case SIOCGIFMTU:
                  ifr = data;
                  ifr->ifr_mtu = ifp->if_mtu;
                  break;
  
          case SIOCGIFDLT:
                  ifr = data;
                  ifr->ifr_dlt = ifp->if_dlt;
                  break;
  
          case SIOCGIFCAP:
                  ifcr = data;
                  ifcr->ifcr_capabilities = ifp->if_capabilities;
                  ifcr->ifcr_capenable = ifp->if_capenable;
                  break;
  
          case SIOCSIFMETRIC:
                  ifr = data;
                  ifp->if_metric = ifr->ifr_metric;
                  break;
  
          case SIOCGIFDATA:
                  ifdr = data;
                  if_export_if_data(ifp, &ifdr->ifdr_data, false);
                  break;
  
          case SIOCGIFINDEX:
                  ifr = data;
                  ifr->ifr_index = ifp->if_index;
                  break;
  
          case SIOCZIFDATA:
                  ifdr = data;
                  if_export_if_data(ifp, &ifdr->ifdr_data, true);
                  getnanotime(&ifp->if_lastchange);
                  break;
          case SIOCSIFMTU:
                  ifr = data;
                  if (ifp->if_mtu == ifr->ifr_mtu)
                          break;
                  ifp->if_mtu = ifr->ifr_mtu;
                  return ENETRESET;
          case SIOCSIFDESCR:
                  error = kauth_authorize_network(kauth_cred_get(),
                      KAUTH_NETWORK_INTERFACE,
                      KAUTH_REQ_NETWORK_INTERFACE_SETPRIV, ifp, KAUTH_ARG(cmd),
                      NULL);
                  if (error)
                          return error;
  
                  ifr = data;
  
                  if (ifr->ifr_buflen > IFDESCRSIZE)
                          return ENAMETOOLONG;
  
                  if (ifr->ifr_buf == NULL || ifr->ifr_buflen == 0) {
                          /* unset description */
                          descr = NULL;
                  } else {
                          descr = kmem_zalloc(IFDESCRSIZE, KM_SLEEP);
                          /*
                           * copy (IFDESCRSIZE - 1) bytes to ensure
                           * terminating nul
                           */
                          error = copyin(ifr->ifr_buf, descr, IFDESCRSIZE - 1);
                          if (error) {
                                  kmem_free(descr, IFDESCRSIZE);
                                  return error;
                          }
                  }
  
                  if (ifp->if_description != NULL)
                          kmem_free(ifp->if_description, IFDESCRSIZE);
  
                  ifp->if_description = descr;
                  break;
  
          case SIOCGIFDESCR:
                  ifr = data;
                  descr = ifp->if_description;
  
                  if (descr == NULL)
                          return ENOMSG;
  
                  if (ifr->ifr_buflen < IFDESCRSIZE)
                          return EINVAL;
  
                  error = copyout(descr, ifr->ifr_buf, IFDESCRSIZE);
                  if (error)
                          return error;
                  break;
  
          default:
                  return ENOTTY;
          }
          return 0;
  }
  
  int
  ifaddrpref_ioctl(struct socket *so, u_long cmd, void *data, struct ifnet *ifp)
  {
          struct if_addrprefreq *ifap = (struct if_addrprefreq *)data;
          struct ifaddr *ifa;
          const struct sockaddr *any, *sa;
          union {
                  struct sockaddr sa;
                  struct sockaddr_storage ss;
          } u, v;
          int s, error = 0;
  
          switch (cmd) {
          case SIOCSIFADDRPREF:
                  error = kauth_authorize_network(kauth_cred_get(),
                      KAUTH_NETWORK_INTERFACE,
                      KAUTH_REQ_NETWORK_INTERFACE_SETPRIV, ifp, KAUTH_ARG(cmd),
                      NULL);
                  if (error)
                          return error;
                  break;
          case SIOCGIFADDRPREF:
                  break;
          default:
                  return EOPNOTSUPP;
          }
  
          /* sanity checks */
          if (data == NULL || ifp == NULL) {
                  panic("invalid argument to %s", __func__);
                  /*NOTREACHED*/
          }
  
          /* address must be specified on ADD and DELETE */
          sa = sstocsa(&ifap->ifap_addr);
          if (sa->sa_family != sofamily(so))
                  return EINVAL;
          if ((any = sockaddr_any(sa)) == NULL || sa->sa_len != any->sa_len)
                  return EINVAL;
  
          sockaddr_externalize(&v.sa, sizeof(v.ss), sa);
  
          s = pserialize_read_enter();
          IFADDR_READER_FOREACH(ifa, ifp) {
                  if (ifa->ifa_addr->sa_family != sa->sa_family)
                          continue;
                  sockaddr_externalize(&u.sa, sizeof(u.ss), ifa->ifa_addr);
                  if (sockaddr_cmp(&u.sa, &v.sa) == 0)
                          break;
          }
          if (ifa == NULL) {
                  error = EADDRNOTAVAIL;
                  goto out;
          }
  
          switch (cmd) {
          case SIOCSIFADDRPREF:
                  ifa->ifa_preference = ifap->ifap_preference;
                  goto out;
          case SIOCGIFADDRPREF:
                  /* fill in the if_laddrreq structure */
                  (void)sockaddr_copy(sstosa(&ifap->ifap_addr),
                      sizeof(ifap->ifap_addr), ifa->ifa_addr);
                  ifap->ifap_preference = ifa->ifa_preference;
                  goto out;
          default:
                  error = EOPNOTSUPP;
          }
  out:
          pserialize_read_exit(s);
          return error;
  }
  
  /*
   * Interface ioctls.
   */
  static int
  doifioctl(struct socket *so, u_long cmd, void *data, struct lwp *l)
  {
          struct ifnet *ifp;
          struct ifreq *ifr;
          int error = 0;
          u_long ocmd = cmd;
          u_short oif_flags;
          struct ifreq ifrb;
          struct oifreq *oifr = NULL;
          int r;
          struct psref psref;
          bool do_if43_post = false;
          bool do_ifm80_post = false;
  
          switch (cmd) {
          case SIOCGIFCONF:
                  return ifconf(cmd, data);
          case SIOCINITIFADDR:
                  return EPERM;
          default:
                  MODULE_HOOK_CALL(uipc_syscalls_40_hook, (cmd, data), enosys(),
                      error);
                  if (error != ENOSYS)
                          return error;
                  MODULE_HOOK_CALL(uipc_syscalls_50_hook, (l, cmd, data),
                      enosys(), error);
                  if (error != ENOSYS)
                          return error;
                  error = 0;
                  break;
          }
  
          ifr = data;
          /* Pre-conversion */
          MODULE_HOOK_CALL(if_cvtcmd_43_hook, (&cmd, ocmd), enosys(), error);
          if (cmd != ocmd) {
                  oifr = data;
                  data = ifr = &ifrb;
                  IFREQO2N_43(oifr, ifr);
                  do_if43_post = true;
          }
          MODULE_HOOK_CALL(ifmedia_80_pre_hook, (ifr, &cmd, &do_ifm80_post),
              enosys(), error);
  
          switch (cmd) {
          case SIOCIFCREATE:
          case SIOCIFDESTROY: {
                  const int bound = curlwp_bind();
                  if (l != NULL) {
                          ifp = if_get(ifr->ifr_name, &psref);
                          error = kauth_authorize_network(l->l_cred,
                              KAUTH_NETWORK_INTERFACE,
                              KAUTH_REQ_NETWORK_INTERFACE_SETPRIV, ifp,
                              KAUTH_ARG(cmd), NULL);
                          if (ifp != NULL)
                                  if_put(ifp, &psref);
                          if (error != 0) {
                                  curlwp_bindx(bound);
                                  return error;
                          }
                  }
                  KERNEL_LOCK_UNLESS_NET_MPSAFE();
                  mutex_enter(&if_clone_mtx);
                  r = (cmd == SIOCIFCREATE) ?
                          if_clone_create(ifr->ifr_name) :
                          if_clone_destroy(ifr->ifr_name);
                  mutex_exit(&if_clone_mtx);
                  KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
                  curlwp_bindx(bound);
                  return r;
              }
          case SIOCIFGCLONERS: {
                  struct if_clonereq *req = (struct if_clonereq *)data;
                  return if_clone_list(req->ifcr_count, req->ifcr_buffer,
                      &req->ifcr_total);
              }
          }
  
          if ((cmd & IOC_IN) == 0 || IOCPARM_LEN(cmd) < sizeof(ifr->ifr_name))
                  return EINVAL;
  
          const int bound = curlwp_bind();
          ifp = if_get(ifr->ifr_name, &psref);
          if (ifp == NULL) {
                  curlwp_bindx(bound);
                  return ENXIO;
          }
  
          switch (cmd) {
          case SIOCALIFADDR:
          case SIOCDLIFADDR:
          case SIOCSIFADDRPREF:
          case SIOCSIFFLAGS:
          case SIOCSIFCAP:
          case SIOCSIFMETRIC:
          case SIOCZIFDATA:
          case SIOCSIFMTU:
          case SIOCSIFPHYADDR:
          case SIOCDIFPHYADDR:
  #ifdef INET6
          case SIOCSIFPHYADDR_IN6:
  #endif
          case SIOCSLIFPHYADDR:
          case SIOCADDMULTI:
          case SIOCDELMULTI:
          case SIOCSETHERCAP:
          case SIOCSIFMEDIA:
          case SIOCSDRVSPEC:
          case SIOCG80211:
          case SIOCS80211:
          case SIOCS80211NWID:
          case SIOCS80211NWKEY:
          case SIOCS80211POWER:
          case SIOCS80211BSSID:
          case SIOCS80211CHANNEL:
          case SIOCSLINKSTR:
                  if (l != NULL) {
                          error = kauth_authorize_network(l->l_cred,
                              KAUTH_NETWORK_INTERFACE,
                              KAUTH_REQ_NETWORK_INTERFACE_SETPRIV, ifp,
                              KAUTH_ARG(cmd), NULL);
                          if (error != 0)
                                  goto out;
                  }
          }
  
          oif_flags = ifp->if_flags;
  
          KERNEL_LOCK_UNLESS_IFP_MPSAFE(ifp);
          IFNET_LOCK(ifp);
  
          error = if_ioctl(ifp, cmd, data);
          if (error != ENOTTY)
                  ;
          else if (so->so_proto == NULL)
                  error = EOPNOTSUPP;
          else {
                  KERNEL_LOCK_IF_IFP_MPSAFE(ifp);
                  MODULE_HOOK_CALL(if_ifioctl_43_hook,
                               (so, ocmd, cmd, data, l), enosys(), error);
                  if (error == ENOSYS)
                          error = (*so->so_proto->pr_usrreqs->pr_ioctl)(so,
                              cmd, data, ifp);
                  KERNEL_UNLOCK_IF_IFP_MPSAFE(ifp);
          }
  
          if (((oif_flags ^ ifp->if_flags) & IFF_UP) != 0) {
                  if ((ifp->if_flags & IFF_UP) != 0) {
                          const int s = splsoftnet();
                          if_up_locked(ifp);
                          splx(s);
                  }
          }
  
          /* Post-conversion */
          if (do_ifm80_post && (error == 0))
                  MODULE_HOOK_CALL(ifmedia_80_post_hook, (ifr, cmd),
                      enosys(), error);
          if (do_if43_post)
                  IFREQN2O_43(oifr, ifr);
  
          IFNET_UNLOCK(ifp);
          KERNEL_UNLOCK_UNLESS_IFP_MPSAFE(ifp);
  out:
          if_put(ifp, &psref);
          curlwp_bindx(bound);
          return error;
  }
  
  /*
   * Return interface configuration
   * of system.  List may be used
   * in later ioctl's (above) to get
   * other information.
   *
   * Each record is a struct ifreq.  Before the addition of
   * sockaddr_storage, the API rule was that sockaddr flavors that did
   * not fit would extend beyond the struct ifreq, with the next struct
   * ifreq starting sa_len beyond the struct sockaddr.  Because the
   * union in struct ifreq includes struct sockaddr_storage, every kind
   * of sockaddr must fit.  Thus, there are no longer any overlength
   * records.
   *
   * Records are added to the user buffer if they fit, and ifc_len is
   * adjusted to the length that was written.  Thus, the user is only
   * assured of getting the complete list if ifc_len on return is at
   * least sizeof(struct ifreq) less than it was on entry.
   *
   * If the user buffer pointer is NULL, this routine copies no data and
   * returns the amount of space that would be needed.
   *
   * Invariants:
   * ifrp points to the next part of the user's buffer to be used.  If
   * ifrp != NULL, space holds the number of bytes remaining that we may
   * write at ifrp.  Otherwise, space holds the number of bytes that
   * would have been written had there been adequate space.
   */
  /*ARGSUSED*/
  static int
  ifconf(u_long cmd, void *data)
  {
          struct ifconf *ifc = (struct ifconf *)data;
          struct ifnet *ifp;
          struct ifaddr *ifa;
          struct ifreq ifr, *ifrp = NULL;
          int space = 0, error = 0;
          const int sz = (int)sizeof(struct ifreq);
          const bool docopy = ifc->ifc_req != NULL;
          struct psref psref;
  
          if (docopy) {
                  if (ifc->ifc_len < 0)
                          return EINVAL;
  
                  space = ifc->ifc_len;
                  ifrp = ifc->ifc_req;
          }
          memset(&ifr, 0, sizeof(ifr));
  
          const int bound = curlwp_bind();
          int s = pserialize_read_enter();
          IFNET_READER_FOREACH(ifp) {
                  psref_acquire(&psref, &ifp->if_psref, ifnet_psref_class);
                  pserialize_read_exit(s);
  
                  (void)strncpy(ifr.ifr_name, ifp->if_xname,
                      sizeof(ifr.ifr_name));
                  if (ifr.ifr_name[sizeof(ifr.ifr_name) - 1] != '\0') {
                          error = ENAMETOOLONG;
                          goto release_exit;
                  }
                  if (IFADDR_READER_EMPTY(ifp)) {
                          /* Interface with no addresses - send zero sockaddr. */
                          memset(&ifr.ifr_addr, 0, sizeof(ifr.ifr_addr));
                          if (!docopy) {
                                  space += sz;
                                  goto next;
                          }
                          if (space >= sz) {
                                  error = copyout(&ifr, ifrp, sz);
                                  if (error != 0)
                                          goto release_exit;
                                  ifrp++;
                                  space -= sz;
                          }
                  }
  
                  s = pserialize_read_enter();
                  IFADDR_READER_FOREACH(ifa, ifp) {
                          struct sockaddr *sa = ifa->ifa_addr;
                          /* all sockaddrs must fit in sockaddr_storage */
                          KASSERT(sa->sa_len <= sizeof(ifr.ifr_ifru));
  
                          if (!docopy) {
                                  space += sz;
                                  continue;
                          }
                          memcpy(&ifr.ifr_space, sa, sa->sa_len);
                          pserialize_read_exit(s);
  
                          if (space >= sz) {
                                  error = copyout(&ifr, ifrp, sz);
                                  if (error != 0)
                                          goto release_exit;
                                  ifrp++; space -= sz;
                          }
                          s = pserialize_read_enter();
                  }
                  pserialize_read_exit(s);
  
  next:
                  s = pserialize_read_enter();
                  psref_release(&psref, &ifp->if_psref, ifnet_psref_class);
          }
          pserialize_read_exit(s);
          curlwp_bindx(bound);
  
          if (docopy) {
                  KASSERT(0 <= space && space <= ifc->ifc_len);
                  ifc->ifc_len -= space;
          } else {
                  KASSERT(space >= 0);
                  ifc->ifc_len = space;
          }
          return 0;
  
  release_exit:
          psref_release(&psref, &ifp->if_psref, ifnet_psref_class);
          curlwp_bindx(bound);
          return error;
  }
  
  int
  ifreq_setaddr(u_long cmd, struct ifreq *ifr, const struct sockaddr *sa)
  {
          uint8_t len = sizeof(ifr->ifr_ifru.ifru_space);
          struct ifreq ifrb;
          struct oifreq *oifr = NULL;
          u_long ocmd = cmd;
          int hook;
  
          MODULE_HOOK_CALL(if_cvtcmd_43_hook, (&cmd, ocmd), enosys(), hook);
          if (hook != ENOSYS) {
                  if (cmd != ocmd) {
                          oifr = (struct oifreq *)(void *)ifr;
                          ifr = &ifrb;
                          IFREQO2N_43(oifr, ifr);
                                  len = sizeof(oifr->ifr_addr);
                  }
          }
  
          if (len < sa->sa_len)
                  return EFBIG;
  
          memset(&ifr->ifr_addr, 0, len);
          sockaddr_copy(&ifr->ifr_addr, len, sa);
  
          if (cmd != ocmd)
                  IFREQN2O_43(oifr, ifr);
          return 0;
  }
  
  /*
   * wrapper function for the drivers which doesn't have if_transmit().
   */
  static int
  if_transmit(struct ifnet *ifp, struct mbuf *m)
  {
          int error;
          size_t pktlen = m->m_pkthdr.len;
          bool mcast = (m->m_flags & M_MCAST) != 0;
  
          const int s = splnet();
  
          IFQ_ENQUEUE(&ifp->if_snd, m, error);
          if (error != 0) {
                  /* mbuf is already freed */
                  goto out;
          }
  
          net_stat_ref_t nsr = IF_STAT_GETREF(ifp);
          if_statadd_ref(nsr, if_obytes, pktlen);
          if (mcast)
                  if_statinc_ref(nsr, if_omcasts);
          IF_STAT_PUTREF(ifp);
  
          if ((ifp->if_flags & IFF_OACTIVE) == 0)
                  if_start_lock(ifp);
  out:
          splx(s);
  
          return error;
  }
  
  int
  if_transmit_lock(struct ifnet *ifp, struct mbuf *m)
  {
          int error;
  
          kmsan_check_mbuf(m);
  
  #ifdef ALTQ
          KERNEL_LOCK(1, NULL);
          if (ALTQ_IS_ENABLED(&ifp->if_snd)) {
                  error = if_transmit(ifp, m);
                  KERNEL_UNLOCK_ONE(NULL);
          } else {
                  KERNEL_UNLOCK_ONE(NULL);
                  error = (*ifp->if_transmit)(ifp, m);
                  /* mbuf is already freed */
          }
  #else /* !ALTQ */
          error = (*ifp->if_transmit)(ifp, m);
          /* mbuf is already freed */
  #endif /* !ALTQ */
  
          return error;
  }
  
  /*
   * Queue message on interface, and start output if interface
   * not yet active.
   */
  int
  ifq_enqueue(struct ifnet *ifp, struct mbuf *m)
  {
  
          return if_transmit_lock(ifp, m);
  }
  
  /*
   * Queue message on interface, possibly using a second fast queue
   */
  int
  ifq_enqueue2(struct ifnet *ifp, struct ifqueue *ifq, struct mbuf *m)
  {
          int error = 0;
  
          if (ifq != NULL
  #ifdef ALTQ
              && ALTQ_IS_ENABLED(&ifp->if_snd) == 0
  #endif
              ) {
                  if (IF_QFULL(ifq)) {
                          IF_DROP(&ifp->if_snd);
                          m_freem(m);
                          if (error == 0)
                                  error = ENOBUFS;
                  } else
                          IF_ENQUEUE(ifq, m);
          } else
                  IFQ_ENQUEUE(&ifp->if_snd, m, error);
          if (error != 0) {
                  if_statinc(ifp, if_oerrors);
                  return error;
          }
          return 0;
  }
  
  int
  if_addr_init(ifnet_t *ifp, struct ifaddr *ifa, const bool src)
  {
          int rc;
  
          KASSERT(IFNET_LOCKED(ifp));
          if (ifp->if_initaddr != NULL)
                  rc = (*ifp->if_initaddr)(ifp, ifa, src);
          else if (src || (rc = if_ioctl(ifp, SIOCSIFDSTADDR, ifa)) == ENOTTY)
                  rc = if_ioctl(ifp, SIOCINITIFADDR, ifa);
  
          return rc;
  }
  
  int
  if_do_dad(struct ifnet *ifp)
  {
          if ((ifp->if_flags & IFF_LOOPBACK) != 0)
                  return 0;
  
          switch (ifp->if_type) {
          case IFT_FAITH:
                  /*
                   * These interfaces do not have the IFF_LOOPBACK flag,
                   * but loop packets back.  We do not have to do DAD on such
                   * interfaces.  We should even omit it, because loop-backed
                   * responses would confuse the DAD procedure.
                   */
                  return 0;
          default:
                  /*
                   * Our DAD routine requires the interface up and running.
                   * However, some interfaces can be up before the RUNNING
                   * status.  Additionally, users may try to assign addresses
                   * before the interface becomes up (or running).
                   * We simply skip DAD in such a case as a work around.
                   * XXX: we should rather mark "tentative" on such addresses,
                   * and do DAD after the interface becomes ready.
                   */
                  if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) !=
                      (IFF_UP | IFF_RUNNING))
                          return 0;
  
                  return 1;
          }
  }
  
  /*
   * if_flags_set(ifp, flags)
   *
   *      Ask ifp to change ifp->if_flags to flags, as if with the
   *      SIOCSIFFLAGS ioctl command.
   *
   *      May sleep.  Caller must hold ifp->if_ioctl_lock, a.k.a
   *      IFNET_LOCK.
   */
  int
  if_flags_set(ifnet_t *ifp, const u_short flags)
  {
          int rc;
  
          KASSERT(IFNET_LOCKED(ifp));
  
          if (ifp->if_setflags != NULL)
                  rc = (*ifp->if_setflags)(ifp, flags);
          else {
                  u_short cantflags, chgdflags;
                  struct ifreq ifr;
  
                  chgdflags = ifp->if_flags ^ flags;
                  cantflags = chgdflags & IFF_CANTCHANGE;
  
                  if (cantflags != 0)
                          ifp->if_flags ^= cantflags;
  
                  /*
                   * Traditionally, we do not call if_ioctl after
                   * setting/clearing only IFF_PROMISC if the interface
                   * isn't IFF_UP.  Uphold that tradition.
                   */
                  if (chgdflags == IFF_PROMISC && (ifp->if_flags & IFF_UP) == 0)
                          return 0;
  
                  memset(&ifr, 0, sizeof(ifr));
  
                  ifr.ifr_flags = flags & ~IFF_CANTCHANGE;
                  rc = if_ioctl(ifp, SIOCSIFFLAGS, &ifr);
  
                  if (rc != 0 && cantflags != 0)
                          ifp->if_flags ^= cantflags;
          }
  
          return rc;
  }
  
  /*
   * if_mcast_op(ifp, cmd, sa)
   *
   *      Apply a multicast command, SIOCADDMULTI/SIOCDELMULTI, to the
   *      interface.  Returns 0 on success, nonzero errno(3) number on
   *      failure.
   *
   *      May sleep.
   *
   *      Use this, not if_ioctl, for the multicast commands.
   */
  int
  if_mcast_op(ifnet_t *ifp, const unsigned long cmd, const struct sockaddr *sa)
  {
          int rc;
          struct ifreq ifr;
  
          switch (cmd) {
          case SIOCADDMULTI:
          case SIOCDELMULTI:
                  break;
          default:
                  panic("invalid ifnet multicast command: 0x%lx", cmd);
          }
  
          ifreq_setaddr(cmd, &ifr, sa);
          rc = if_ioctl(ifp, cmd, &ifr);
  
          return rc;
  }
  
  static void
  sysctl_sndq_setup(struct sysctllog **clog, const char *ifname,
      struct ifaltq *ifq)
  {
          const struct sysctlnode *cnode, *rnode;
  
          if (sysctl_createv(clog, 0, NULL, &rnode,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_NODE, "interfaces",
                         SYSCTL_DESCR("Per-interface controls"),
                         NULL, 0, NULL, 0,
                         CTL_NET, CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
  
          if (sysctl_createv(clog, 0, &rnode, &rnode,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_NODE, ifname,
                         SYSCTL_DESCR("Interface controls"),
                         NULL, 0, NULL, 0,
                         CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
  
          if (sysctl_createv(clog, 0, &rnode, &rnode,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_NODE, "sndq",
                         SYSCTL_DESCR("Interface output queue controls"),
                         NULL, 0, NULL, 0,
                         CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
  
          if (sysctl_createv(clog, 0, &rnode, &cnode,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_INT, "len",
                         SYSCTL_DESCR("Current output queue length"),
                         NULL, 0, &ifq->ifq_len, 0,
                         CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
  
          if (sysctl_createv(clog, 0, &rnode, &cnode,
                         CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
                         CTLTYPE_INT, "maxlen",
                         SYSCTL_DESCR("Maximum allowed output queue length"),
                         NULL, 0, &ifq->ifq_maxlen, 0,
                         CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
  
          if (sysctl_createv(clog, 0, &rnode, &cnode,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_QUAD, "drops",
                         SYSCTL_DESCR("Packets dropped due to full output queue"),
                         NULL, 0, &ifq->ifq_drops, 0,
                         CTL_CREATE, CTL_EOL) != 0)
                  goto bad;
  
          return;
  bad:
          printf("%s: could not attach sysctl nodes\n", ifname);
          return;
  }
  
  static int
  if_sdl_sysctl(SYSCTLFN_ARGS)
  {
          struct ifnet *ifp;
          const struct sockaddr_dl *sdl;
          struct psref psref;
          int error = 0;
  
          if (namelen != 1)
                  return EINVAL;
  
          const int bound = curlwp_bind();
          ifp = if_get_byindex(name[0], &psref);
          if (ifp == NULL) {
                  error = ENODEV;
                  goto out0;
          }
  
          sdl = ifp->if_sadl;
          if (sdl == NULL) {
                  *oldlenp = 0;
                  goto out1;
          }
  
          if (oldp == NULL) {
                  *oldlenp = sdl->sdl_alen;
                  goto out1;
          }
  
          if (*oldlenp >= sdl->sdl_alen)
                  *oldlenp = sdl->sdl_alen;
          error = sysctl_copyout(l, &sdl->sdl_data[sdl->sdl_nlen],
              oldp, *oldlenp);
  out1:
          if_put(ifp, &psref);
  out0:
          curlwp_bindx(bound);
          return error;
  }
  
  static void
  if_sysctl_setup(struct sysctllog **clog)
  {
          const struct sysctlnode *rnode = NULL;
  
          sysctl_createv(clog, 0, NULL, &rnode,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_NODE, "sdl",
                         SYSCTL_DESCR("Get active link-layer address"),
                         if_sdl_sysctl, 0, NULL, 0,
                         CTL_NET, CTL_CREATE, CTL_EOL);
  }