iface.c

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/*
 * Interface handling (except master interface)
 *
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright (c) 2006 Jiri Benc <[email protected]>
 * Copyright 2008, Johannes Berg <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/if_arp.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <net/mac80211.h>
#include <net/ieee80211_radiotap.h>
#include "ieee80211_i.h"
#include "sta_info.h"
#include "debugfs_netdev.h"
#include "mesh.h"
#include "led.h"
#include "driver-ops.h"
#include "wme.h"
#include "rate.h"

static u32 ieee80211_idle_off(struct ieee80211_local *local,
                  const char *reason)
{
    if (!(local->hw.conf.flags & IEEE80211_CONF_IDLE))
        return 0;

    local->hw.conf.flags &= ~IEEE80211_CONF_IDLE;
    return IEEE80211_CONF_CHANGE_IDLE;
}

static u32 ieee80211_idle_on(struct ieee80211_local *local)
{
    if (local->hw.conf.flags & IEEE80211_CONF_IDLE)
        return 0;

    drv_flush(local, false);

    local->hw.conf.flags |= IEEE80211_CONF_IDLE;
    return IEEE80211_CONF_CHANGE_IDLE;
}

static u32 __ieee80211_recalc_idle(struct ieee80211_local *local)
{
    struct ieee80211_sub_if_data *sdata;
    int count = 0;
    bool working = false, scanning = false;
    unsigned int led_trig_start = 0, led_trig_stop = 0;
    struct ieee80211_roc_work *roc;

#ifdef CONFIG_PROVE_LOCKING
    WARN_ON(debug_locks && !lockdep_rtnl_is_held() &&
        !lockdep_is_held(&local->iflist_mtx));
#endif
    lockdep_assert_held(&local->mtx);

    list_for_each_entry(sdata, &local->interfaces, list) {
        if (!ieee80211_sdata_running(sdata)) {
            sdata->vif.bss_conf.idle = true;
            continue;
        }

        sdata->old_idle = sdata->vif.bss_conf.idle;

        /* do not count disabled managed interfaces */
        if (sdata->vif.type == NL80211_IFTYPE_STATION &&
            !sdata->u.mgd.associated &&
            !sdata->u.mgd.auth_data &&
            !sdata->u.mgd.assoc_data) {
            sdata->vif.bss_conf.idle = true;
            continue;
        }
        /* do not count unused IBSS interfaces */
        if (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
            !sdata->u.ibss.ssid_len) {
            sdata->vif.bss_conf.idle = true;
            continue;
        }

        if (sdata->vif.type == NL80211_IFTYPE_P2P_DEVICE)
            continue;

        /* count everything else */
        sdata->vif.bss_conf.idle = false;
        count++;
    }

    if (!local->ops->remain_on_channel) {
        list_for_each_entry(roc, &local->roc_list, list) {
            working = true;
            roc->sdata->vif.bss_conf.idle = false;
        }
    }

    sdata = rcu_dereference_protected(local->scan_sdata,
                      lockdep_is_held(&local->mtx));
    if (sdata && !(local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)) {
        scanning = true;
        sdata->vif.bss_conf.idle = false;
    }

    list_for_each_entry(sdata, &local->interfaces, list) {
        if (sdata->vif.type == NL80211_IFTYPE_MONITOR ||
            sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
            sdata->vif.type == NL80211_IFTYPE_P2P_DEVICE)
            continue;
        if (sdata->old_idle == sdata->vif.bss_conf.idle)
            continue;
        if (!ieee80211_sdata_running(sdata))
            continue;
        ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_IDLE);
    }

    if (working || scanning)
        led_trig_start |= IEEE80211_TPT_LEDTRIG_FL_WORK;
    else
        led_trig_stop |= IEEE80211_TPT_LEDTRIG_FL_WORK;

    if (count)
        led_trig_start |= IEEE80211_TPT_LEDTRIG_FL_CONNECTED;
    else
        led_trig_stop |= IEEE80211_TPT_LEDTRIG_FL_CONNECTED;

    ieee80211_mod_tpt_led_trig(local, led_trig_start, led_trig_stop);

    if (working)
        return ieee80211_idle_off(local, "working");
    if (scanning)
        return ieee80211_idle_off(local, "scanning");
    if (!count)
        return ieee80211_idle_on(local);
    else
        return ieee80211_idle_off(local, "in use");

    return 0;
}

void ieee80211_recalc_idle(struct ieee80211_local *local)
{
    u32 chg;

    mutex_lock(&local->iflist_mtx);
    chg = __ieee80211_recalc_idle(local);
    mutex_unlock(&local->iflist_mtx);
    if (chg)
        ieee80211_hw_config(local, chg);
}

static int ieee80211_change_mtu(struct net_device *dev, int new_mtu)
{
    int meshhdrlen;
    struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);

    meshhdrlen = (sdata->vif.type == NL80211_IFTYPE_MESH_POINT) ? 5 : 0;

    /* FIX: what would be proper limits for MTU?
     * This interface uses 802.3 frames. */
    if (new_mtu < 256 ||
        new_mtu > IEEE80211_MAX_DATA_LEN - 24 - 6 - meshhdrlen) {
        return -EINVAL;
    }

    dev->mtu = new_mtu;
    return 0;
}

static int ieee80211_change_mac(struct net_device *dev, void *addr)
{
    struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
    struct sockaddr *sa = addr;
    int ret;

    if (ieee80211_sdata_running(sdata))
        return -EBUSY;

    ret = eth_mac_addr(dev, sa);

    if (ret == 0)
        memcpy(sdata->vif.addr, sa->sa_data, ETH_ALEN);

    return ret;
}

static inline int identical_mac_addr_allowed(int type1, int type2)
{
    return type1 == NL80211_IFTYPE_MONITOR ||
        type2 == NL80211_IFTYPE_MONITOR ||
        type1 == NL80211_IFTYPE_P2P_DEVICE ||
        type2 == NL80211_IFTYPE_P2P_DEVICE ||
        (type1 == NL80211_IFTYPE_AP && type2 == NL80211_IFTYPE_WDS) ||
        (type1 == NL80211_IFTYPE_WDS &&
            (type2 == NL80211_IFTYPE_WDS ||
             type2 == NL80211_IFTYPE_AP)) ||
        (type1 == NL80211_IFTYPE_AP && type2 == NL80211_IFTYPE_AP_VLAN) ||
        (type1 == NL80211_IFTYPE_AP_VLAN &&
            (type2 == NL80211_IFTYPE_AP ||
             type2 == NL80211_IFTYPE_AP_VLAN));
}

static int ieee80211_check_concurrent_iface(struct ieee80211_sub_if_data *sdata,
                        enum nl80211_iftype iftype)
{
    struct ieee80211_local *local = sdata->local;
    struct ieee80211_sub_if_data *nsdata;

    ASSERT_RTNL();

    /* we hold the RTNL here so can safely walk the list */
    list_for_each_entry(nsdata, &local->interfaces, list) {
        if (nsdata != sdata && ieee80211_sdata_running(nsdata)) {
            /*
             * Allow only a single IBSS interface to be up at any
             * time. This is restricted because beacon distribution
             * cannot work properly if both are in the same IBSS.
             *
             * To remove this restriction we'd have to disallow them
             * from setting the same SSID on different IBSS interfaces
             * belonging to the same hardware. Then, however, we're
             * faced with having to adopt two different TSF timers...
             */
            if (iftype == NL80211_IFTYPE_ADHOC &&
                nsdata->vif.type == NL80211_IFTYPE_ADHOC)
                return -EBUSY;

            /*
             * The remaining checks are only performed for interfaces
             * with the same MAC address.
             */
            if (!ether_addr_equal(sdata->vif.addr,
                          nsdata->vif.addr))
                continue;

            /*
             * check whether it may have the same address
             */
            if (!identical_mac_addr_allowed(iftype,
                            nsdata->vif.type))
                return -ENOTUNIQ;

            /*
             * can only add VLANs to enabled APs
             */
            if (iftype == NL80211_IFTYPE_AP_VLAN &&
                nsdata->vif.type == NL80211_IFTYPE_AP)
                sdata->bss = &nsdata->u.ap;
        }
    }

    return 0;
}

static int ieee80211_check_queues(struct ieee80211_sub_if_data *sdata)
{
    int n_queues = sdata->local->hw.queues;
    int i;

    if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE) {
        for (i = 0; i < IEEE80211_NUM_ACS; i++) {
            if (WARN_ON_ONCE(sdata->vif.hw_queue[i] ==
                     IEEE80211_INVAL_HW_QUEUE))
                return -EINVAL;
            if (WARN_ON_ONCE(sdata->vif.hw_queue[i] >=
                     n_queues))
                return -EINVAL;
        }
    }

    if ((sdata->vif.type != NL80211_IFTYPE_AP) ||
        !(sdata->local->hw.flags & IEEE80211_HW_QUEUE_CONTROL)) {
        sdata->vif.cab_queue = IEEE80211_INVAL_HW_QUEUE;
        return 0;
    }

    if (WARN_ON_ONCE(sdata->vif.cab_queue == IEEE80211_INVAL_HW_QUEUE))
        return -EINVAL;

    if (WARN_ON_ONCE(sdata->vif.cab_queue >= n_queues))
        return -EINVAL;

    return 0;
}

void ieee80211_adjust_monitor_flags(struct ieee80211_sub_if_data *sdata,
                    const int offset)
{
    struct ieee80211_local *local = sdata->local;
    u32 flags = sdata->u.mntr_flags;

#define ADJUST(_f, _s)  do {                    \
    if (flags & MONITOR_FLAG_##_f)              \
        local->fif_##_s += offset;          \
    } while (0)

    ADJUST(FCSFAIL, fcsfail);
    ADJUST(PLCPFAIL, plcpfail);
    ADJUST(CONTROL, control);
    ADJUST(CONTROL, pspoll);
    ADJUST(OTHER_BSS, other_bss);

#undef ADJUST
}

static void ieee80211_set_default_queues(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_local *local = sdata->local;
    int i;

    for (i = 0; i < IEEE80211_NUM_ACS; i++) {
        if (local->hw.flags & IEEE80211_HW_QUEUE_CONTROL)
            sdata->vif.hw_queue[i] = IEEE80211_INVAL_HW_QUEUE;
        else if (local->hw.queues >= IEEE80211_NUM_ACS)
            sdata->vif.hw_queue[i] = i;
        else
            sdata->vif.hw_queue[i] = 0;
    }
    sdata->vif.cab_queue = IEEE80211_INVAL_HW_QUEUE;
}

static int ieee80211_add_virtual_monitor(struct ieee80211_local *local)
{
    struct ieee80211_sub_if_data *sdata;
    int ret = 0;

    if (!(local->hw.flags & IEEE80211_HW_WANT_MONITOR_VIF))
        return 0;

    mutex_lock(&local->iflist_mtx);

    if (local->monitor_sdata)
        goto out_unlock;

    sdata = kzalloc(sizeof(*sdata) + local->hw.vif_data_size, GFP_KERNEL);
    if (!sdata) {
        ret = -ENOMEM;
        goto out_unlock;
    }

    /* set up data */
    sdata->local = local;
    sdata->vif.type = NL80211_IFTYPE_MONITOR;
    snprintf(sdata->name, IFNAMSIZ, "%s-monitor",
         wiphy_name(local->hw.wiphy));

    ieee80211_set_default_queues(sdata);

    ret = drv_add_interface(local, sdata);
    if (WARN_ON(ret)) {
        /* ok .. stupid driver, it asked for this! */
        kfree(sdata);
        goto out_unlock;
    }

    ret = ieee80211_check_queues(sdata);
    if (ret) {
        kfree(sdata);
        goto out_unlock;
    }

    rcu_assign_pointer(local->monitor_sdata, sdata);
 out_unlock:
    mutex_unlock(&local->iflist_mtx);
    return ret;
}

static void ieee80211_del_virtual_monitor(struct ieee80211_local *local)
{
    struct ieee80211_sub_if_data *sdata;

    if (!(local->hw.flags & IEEE80211_HW_WANT_MONITOR_VIF))
        return;

    mutex_lock(&local->iflist_mtx);

    sdata = rcu_dereference_protected(local->monitor_sdata,
                      lockdep_is_held(&local->iflist_mtx));
    if (!sdata)
        goto out_unlock;

    rcu_assign_pointer(local->monitor_sdata, NULL);
    synchronize_net();

    drv_remove_interface(local, sdata);

    kfree(sdata);
 out_unlock:
    mutex_unlock(&local->iflist_mtx);
}

/*
 * NOTE: Be very careful when changing this function, it must NOT return
 * an error on interface type changes that have been pre-checked, so most
 * checks should be in ieee80211_check_concurrent_iface.
 */
int ieee80211_do_open(struct wireless_dev *wdev, bool coming_up)
{
    struct ieee80211_sub_if_data *sdata = IEEE80211_WDEV_TO_SUB_IF(wdev);
    struct net_device *dev = wdev->netdev;
    struct ieee80211_local *local = sdata->local;
    struct sta_info *sta;
    u32 changed = 0;
    int res;
    u32 hw_reconf_flags = 0;

    switch (sdata->vif.type) {
    case NL80211_IFTYPE_WDS:
        if (!is_valid_ether_addr(sdata->u.wds.remote_addr))
            return -ENOLINK;
        break;
    case NL80211_IFTYPE_AP_VLAN: {
        struct ieee80211_sub_if_data *master;

        if (!sdata->bss)
            return -ENOLINK;

        list_add(&sdata->u.vlan.list, &sdata->bss->vlans);

        master = container_of(sdata->bss,
                      struct ieee80211_sub_if_data, u.ap);
        sdata->control_port_protocol =
            master->control_port_protocol;
        sdata->control_port_no_encrypt =
            master->control_port_no_encrypt;
        break;
        }
    case NL80211_IFTYPE_AP:
        sdata->bss = &sdata->u.ap;
        break;
    case NL80211_IFTYPE_MESH_POINT:
    case NL80211_IFTYPE_STATION:
    case NL80211_IFTYPE_MONITOR:
    case NL80211_IFTYPE_ADHOC:
    case NL80211_IFTYPE_P2P_DEVICE:
        /* no special treatment */
        break;
    case NL80211_IFTYPE_UNSPECIFIED:
    case NUM_NL80211_IFTYPES:
    case NL80211_IFTYPE_P2P_CLIENT:
    case NL80211_IFTYPE_P2P_GO:
        /* cannot happen */
        WARN_ON(1);
        break;
    }

    if (local->open_count == 0) {
        res = drv_start(local);
        if (res)
            goto err_del_bss;
        if (local->ops->napi_poll)
            napi_enable(&local->napi);
        /* we're brought up, everything changes */
        hw_reconf_flags = ~0;
        ieee80211_led_radio(local, true);
        ieee80211_mod_tpt_led_trig(local,
                       IEEE80211_TPT_LEDTRIG_FL_RADIO, 0);
    }

    /*
     * Copy the hopefully now-present MAC address to
     * this interface, if it has the special null one.
     */
    if (dev && is_zero_ether_addr(dev->dev_addr)) {
        memcpy(dev->dev_addr,
               local->hw.wiphy->perm_addr,
               ETH_ALEN);
        memcpy(dev->perm_addr, dev->dev_addr, ETH_ALEN);

        if (!is_valid_ether_addr(dev->dev_addr)) {
            res = -EADDRNOTAVAIL;
            goto err_stop;
        }
    }

    switch (sdata->vif.type) {
    case NL80211_IFTYPE_AP_VLAN:
        /* no need to tell driver, but set carrier */
        if (rtnl_dereference(sdata->bss->beacon))
            netif_carrier_on(dev);
        else
            netif_carrier_off(dev);
        break;
    case NL80211_IFTYPE_MONITOR:
        if (sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES) {
            local->cooked_mntrs++;
            break;
        }

        if (local->monitors == 0 && local->open_count == 0) {
            res = ieee80211_add_virtual_monitor(local);
            if (res)
                goto err_stop;
        }

        /* must be before the call to ieee80211_configure_filter */
        local->monitors++;
        if (local->monitors == 1) {
            local->hw.conf.flags |= IEEE80211_CONF_MONITOR;
            hw_reconf_flags |= IEEE80211_CONF_CHANGE_MONITOR;
        }

        ieee80211_adjust_monitor_flags(sdata, 1);
        ieee80211_configure_filter(local);

        netif_carrier_on(dev);
        break;
    default:
        if (coming_up) {
            ieee80211_del_virtual_monitor(local);

            res = drv_add_interface(local, sdata);
            if (res)
                goto err_stop;
            res = ieee80211_check_queues(sdata);
            if (res)
                goto err_del_interface;
        }

        if (sdata->vif.type == NL80211_IFTYPE_AP) {
            local->fif_pspoll++;
            local->fif_probe_req++;

            ieee80211_configure_filter(local);
        } else if (sdata->vif.type == NL80211_IFTYPE_ADHOC) {
            local->fif_probe_req++;
        }

        if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE)
            changed |= ieee80211_reset_erp_info(sdata);
        ieee80211_bss_info_change_notify(sdata, changed);

        switch (sdata->vif.type) {
        case NL80211_IFTYPE_STATION:
        case NL80211_IFTYPE_ADHOC:
        case NL80211_IFTYPE_AP:
        case NL80211_IFTYPE_MESH_POINT:
            netif_carrier_off(dev);
            break;
        case NL80211_IFTYPE_WDS:
        case NL80211_IFTYPE_P2P_DEVICE:
            break;
        default:
            netif_carrier_on(dev);
        }

        /*
         * set default queue parameters so drivers don't
         * need to initialise the hardware if the hardware
         * doesn't start up with sane defaults
         */
        ieee80211_set_wmm_default(sdata, true);
    }

    set_bit(SDATA_STATE_RUNNING, &sdata->state);

    if (sdata->vif.type == NL80211_IFTYPE_WDS) {
        /* Create STA entry for the WDS peer */
        sta = sta_info_alloc(sdata, sdata->u.wds.remote_addr,
                     GFP_KERNEL);
        if (!sta) {
            res = -ENOMEM;
            goto err_del_interface;
        }

        sta_info_pre_move_state(sta, IEEE80211_STA_AUTH);
        sta_info_pre_move_state(sta, IEEE80211_STA_ASSOC);
        sta_info_pre_move_state(sta, IEEE80211_STA_AUTHORIZED);

        res = sta_info_insert(sta);
        if (res) {
            /* STA has been freed */
            goto err_del_interface;
        }

        rate_control_rate_init(sta);
        netif_carrier_on(dev);
    } else if (sdata->vif.type == NL80211_IFTYPE_P2P_DEVICE) {
        rcu_assign_pointer(local->p2p_sdata, sdata);
    }

    /*
     * set_multicast_list will be invoked by the networking core
     * which will check whether any increments here were done in
     * error and sync them down to the hardware as filter flags.
     */
    if (sdata->flags & IEEE80211_SDATA_ALLMULTI)
        atomic_inc(&local->iff_allmultis);

    if (sdata->flags & IEEE80211_SDATA_PROMISC)
        atomic_inc(&local->iff_promiscs);

    mutex_lock(&local->mtx);
    hw_reconf_flags |= __ieee80211_recalc_idle(local);
    mutex_unlock(&local->mtx);

    if (coming_up)
        local->open_count++;

    if (hw_reconf_flags)
        ieee80211_hw_config(local, hw_reconf_flags);

    ieee80211_recalc_ps(local, -1);

    if (dev)
        netif_tx_start_all_queues(dev);

    return 0;
 err_del_interface:
    drv_remove_interface(local, sdata);
 err_stop:
    if (!local->open_count)
        drv_stop(local);
 err_del_bss:
    sdata->bss = NULL;
    if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
        list_del(&sdata->u.vlan.list);
    /* might already be clear but that doesn't matter */
    clear_bit(SDATA_STATE_RUNNING, &sdata->state);
    return res;
}

static int ieee80211_open(struct net_device *dev)
{
    struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
    int err;

    /* fail early if user set an invalid address */
    if (!is_valid_ether_addr(dev->dev_addr))
        return -EADDRNOTAVAIL;

    err = ieee80211_check_concurrent_iface(sdata, sdata->vif.type);
    if (err)
        return err;

    return ieee80211_do_open(&sdata->wdev, true);
}

static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
                  bool going_down)
{
    struct ieee80211_local *local = sdata->local;
    unsigned long flags;
    struct sk_buff *skb, *tmp;
    u32 hw_reconf_flags = 0;
    int i;
    enum nl80211_channel_type orig_ct;

    clear_bit(SDATA_STATE_RUNNING, &sdata->state);

    if (rcu_access_pointer(local->scan_sdata) == sdata)
        ieee80211_scan_cancel(local);

    /*
     * Stop TX on this interface first.
     */
    if (sdata->dev)
        netif_tx_stop_all_queues(sdata->dev);

    ieee80211_roc_purge(sdata);

    /*
     * Remove all stations associated with this interface.
     *
     * This must be done before calling ops->remove_interface()
     * because otherwise we can later invoke ops->sta_notify()
     * whenever the STAs are removed, and that invalidates driver
     * assumptions about always getting a vif pointer that is valid
     * (because if we remove a STA after ops->remove_interface()
     * the driver will have removed the vif info already!)
     *
     * This is relevant only in AP, WDS and mesh modes, since in
     * all other modes we've already removed all stations when
     * disconnecting etc.
     */
    sta_info_flush(local, sdata);

    /*
     * Don't count this interface for promisc/allmulti while it
     * is down. dev_mc_unsync() will invoke set_multicast_list
     * on the master interface which will sync these down to the
     * hardware as filter flags.
     */
    if (sdata->flags & IEEE80211_SDATA_ALLMULTI)
        atomic_dec(&local->iff_allmultis);

    if (sdata->flags & IEEE80211_SDATA_PROMISC)
        atomic_dec(&local->iff_promiscs);

    if (sdata->vif.type == NL80211_IFTYPE_AP) {
        local->fif_pspoll--;
        local->fif_probe_req--;
    } else if (sdata->vif.type == NL80211_IFTYPE_ADHOC) {
        local->fif_probe_req--;
    }

    if (sdata->dev) {
        netif_addr_lock_bh(sdata->dev);
        spin_lock_bh(&local->filter_lock);
        __hw_addr_unsync(&local->mc_list, &sdata->dev->mc,
                 sdata->dev->addr_len);
        spin_unlock_bh(&local->filter_lock);
        netif_addr_unlock_bh(sdata->dev);

        ieee80211_configure_filter(local);
    }

    del_timer_sync(&local->dynamic_ps_timer);
    cancel_work_sync(&local->dynamic_ps_enable_work);

    /* APs need special treatment */
    if (sdata->vif.type == NL80211_IFTYPE_AP) {
        struct ieee80211_sub_if_data *vlan, *tmpsdata;
        struct beacon_data *old_beacon =
            rtnl_dereference(sdata->u.ap.beacon);
        struct probe_resp *old_probe_resp =
            rtnl_dereference(sdata->u.ap.probe_resp);

        /* sdata_running will return false, so this will disable */
        ieee80211_bss_info_change_notify(sdata,
                         BSS_CHANGED_BEACON_ENABLED);

        /* remove beacon and probe response */
        RCU_INIT_POINTER(sdata->u.ap.beacon, NULL);
        RCU_INIT_POINTER(sdata->u.ap.probe_resp, NULL);
        synchronize_rcu();
        kfree(old_beacon);
        kfree(old_probe_resp);

        /* down all dependent devices, that is VLANs */
        list_for_each_entry_safe(vlan, tmpsdata, &sdata->u.ap.vlans,
                     u.vlan.list)
            dev_close(vlan->dev);
        WARN_ON(!list_empty(&sdata->u.ap.vlans));

        /* free all potentially still buffered bcast frames */
        local->total_ps_buffered -= skb_queue_len(&sdata->u.ap.ps_bc_buf);
        skb_queue_purge(&sdata->u.ap.ps_bc_buf);
    } else if (sdata->vif.type == NL80211_IFTYPE_STATION) {
        ieee80211_mgd_stop(sdata);
    }

    if (going_down)
        local->open_count--;

    switch (sdata->vif.type) {
    case NL80211_IFTYPE_AP_VLAN:
        list_del(&sdata->u.vlan.list);
        /* no need to tell driver */
        break;
    case NL80211_IFTYPE_MONITOR:
        if (sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES) {
            local->cooked_mntrs--;
            break;
        }

        local->monitors--;
        if (local->monitors == 0) {
            local->hw.conf.flags &= ~IEEE80211_CONF_MONITOR;
            hw_reconf_flags |= IEEE80211_CONF_CHANGE_MONITOR;
            ieee80211_del_virtual_monitor(local);
        }

        ieee80211_adjust_monitor_flags(sdata, -1);
        ieee80211_configure_filter(local);
        break;
    case NL80211_IFTYPE_P2P_DEVICE:
        /* relies on synchronize_rcu() below */
        rcu_assign_pointer(local->p2p_sdata, NULL);
        /* fall through */
    default:
        flush_work(&sdata->work);
        /*
         * When we get here, the interface is marked down.
         * Call rcu_barrier() to wait both for the RX path
         * should it be using the interface and enqueuing
         * frames at this very time on another CPU, and
         * for the sta free call_rcu callbacks.
         */
        rcu_barrier();

        /*
         * free_sta_rcu() enqueues a work for the actual
         * sta cleanup, so we need to flush it while
         * sdata is still valid.
         */
        flush_workqueue(local->workqueue);

        skb_queue_purge(&sdata->skb_queue);

        /*
         * Free all remaining keys, there shouldn't be any,
         * except maybe group keys in AP more or WDS?
         */
        ieee80211_free_keys(sdata);

        if (going_down)
            drv_remove_interface(local, sdata);
    }

    sdata->bss = NULL;

    mutex_lock(&local->mtx);
    hw_reconf_flags |= __ieee80211_recalc_idle(local);
    mutex_unlock(&local->mtx);

    ieee80211_recalc_ps(local, -1);

    if (local->open_count == 0) {
        if (local->ops->napi_poll)
            napi_disable(&local->napi);
        ieee80211_clear_tx_pending(local);
        ieee80211_stop_device(local);

        /* no reconfiguring after stop! */
        hw_reconf_flags = 0;
    }

    /* Re-calculate channel-type, in case there are multiple vifs
     * on different channel types.
     */
    orig_ct = local->_oper_channel_type;
    ieee80211_set_channel_type(local, NULL, NL80211_CHAN_NO_HT);

    /* do after stop to avoid reconfiguring when we stop anyway */
    if (hw_reconf_flags || (orig_ct != local->_oper_channel_type))
        ieee80211_hw_config(local, hw_reconf_flags);

    spin_lock_irqsave(&local->queue_stop_reason_lock, flags);
    for (i = 0; i < IEEE80211_MAX_QUEUES; i++) {
        skb_queue_walk_safe(&local->pending[i], skb, tmp) {
            struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
            if (info->control.vif == &sdata->vif) {
                __skb_unlink(skb, &local->pending[i]);
                ieee80211_free_txskb(&local->hw, skb);
            }
        }
    }
    spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags);

    if (local->monitors == local->open_count && local->monitors > 0)
        ieee80211_add_virtual_monitor(local);
}

static int ieee80211_stop(struct net_device *dev)
{
    struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);

    ieee80211_do_stop(sdata, true);

    return 0;
}

static void ieee80211_set_multicast_list(struct net_device *dev)
{
    struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
    struct ieee80211_local *local = sdata->local;
    int allmulti, promisc, sdata_allmulti, sdata_promisc;

    allmulti = !!(dev->flags & IFF_ALLMULTI);
    promisc = !!(dev->flags & IFF_PROMISC);
    sdata_allmulti = !!(sdata->flags & IEEE80211_SDATA_ALLMULTI);
    sdata_promisc = !!(sdata->flags & IEEE80211_SDATA_PROMISC);

    if (allmulti != sdata_allmulti) {
        if (dev->flags & IFF_ALLMULTI)
            atomic_inc(&local->iff_allmultis);
        else
            atomic_dec(&local->iff_allmultis);
        sdata->flags ^= IEEE80211_SDATA_ALLMULTI;
    }

    if (promisc != sdata_promisc) {
        if (dev->flags & IFF_PROMISC)
            atomic_inc(&local->iff_promiscs);
        else
            atomic_dec(&local->iff_promiscs);
        sdata->flags ^= IEEE80211_SDATA_PROMISC;
    }
    spin_lock_bh(&local->filter_lock);
    __hw_addr_sync(&local->mc_list, &dev->mc, dev->addr_len);
    spin_unlock_bh(&local->filter_lock);
    ieee80211_queue_work(&local->hw, &local->reconfig_filter);
}

/*
 * Called when the netdev is removed or, by the code below, before
 * the interface type changes.
 */
static void ieee80211_teardown_sdata(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_local *local = sdata->local;
    int flushed;
    int i;

    /* free extra data */
    ieee80211_free_keys(sdata);

    ieee80211_debugfs_remove_netdev(sdata);

    for (i = 0; i < IEEE80211_FRAGMENT_MAX; i++)
        __skb_queue_purge(&sdata->fragments[i].skb_list);
    sdata->fragment_next = 0;

    if (ieee80211_vif_is_mesh(&sdata->vif))
        mesh_rmc_free(sdata);

    flushed = sta_info_flush(local, sdata);
    WARN_ON(flushed);
}

static void ieee80211_uninit(struct net_device *dev)
{
    ieee80211_teardown_sdata(IEEE80211_DEV_TO_SUB_IF(dev));
}

static u16 ieee80211_netdev_select_queue(struct net_device *dev,
                     struct sk_buff *skb)
{
    return ieee80211_select_queue(IEEE80211_DEV_TO_SUB_IF(dev), skb);
}

static const struct net_device_ops ieee80211_dataif_ops = {
    .ndo_open       = ieee80211_open,
    .ndo_stop       = ieee80211_stop,
    .ndo_uninit     = ieee80211_uninit,
    .ndo_start_xmit     = ieee80211_subif_start_xmit,
    .ndo_set_rx_mode    = ieee80211_set_multicast_list,
    .ndo_change_mtu     = ieee80211_change_mtu,
    .ndo_set_mac_address    = ieee80211_change_mac,
    .ndo_select_queue   = ieee80211_netdev_select_queue,
};

static u16 ieee80211_monitor_select_queue(struct net_device *dev,
                      struct sk_buff *skb)
{
    struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
    struct ieee80211_local *local = sdata->local;
    struct ieee80211_hdr *hdr;
    struct ieee80211_radiotap_header *rtap = (void *)skb->data;

    if (local->hw.queues < IEEE80211_NUM_ACS)
        return 0;

    if (skb->len < 4 ||
        skb->len < le16_to_cpu(rtap->it_len) + 2 /* frame control */)
        return 0; /* doesn't matter, frame will be dropped */

    hdr = (void *)((u8 *)skb->data + le16_to_cpu(rtap->it_len));

    return ieee80211_select_queue_80211(sdata, skb, hdr);
}

static const struct net_device_ops ieee80211_monitorif_ops = {
    .ndo_open       = ieee80211_open,
    .ndo_stop       = ieee80211_stop,
    .ndo_uninit     = ieee80211_uninit,
    .ndo_start_xmit     = ieee80211_monitor_start_xmit,
    .ndo_set_rx_mode    = ieee80211_set_multicast_list,
    .ndo_change_mtu     = ieee80211_change_mtu,
    .ndo_set_mac_address    = eth_mac_addr,
    .ndo_select_queue   = ieee80211_monitor_select_queue,
};

static void ieee80211_if_setup(struct net_device *dev)
{
    ether_setup(dev);
    dev->priv_flags &= ~IFF_TX_SKB_SHARING;
    dev->netdev_ops = &ieee80211_dataif_ops;
    dev->destructor = free_netdev;
}

static void ieee80211_iface_work(struct work_struct *work)
{
    struct ieee80211_sub_if_data *sdata =
        container_of(work, struct ieee80211_sub_if_data, work);
    struct ieee80211_local *local = sdata->local;
    struct sk_buff *skb;
    struct sta_info *sta;
    struct ieee80211_ra_tid *ra_tid;

    if (!ieee80211_sdata_running(sdata))
        return;

    if (local->scanning)
        return;

    /*
     * ieee80211_queue_work() should have picked up most cases,
     * here we'll pick the rest.
     */
    if (WARN(local->suspended,
         "interface work scheduled while going to suspend\n"))
        return;

    /* first process frames */
    while ((skb = skb_dequeue(&sdata->skb_queue))) {
        struct ieee80211_mgmt *mgmt = (void *)skb->data;

        if (skb->pkt_type == IEEE80211_SDATA_QUEUE_AGG_START) {
            ra_tid = (void *)&skb->cb;
            ieee80211_start_tx_ba_cb(&sdata->vif, ra_tid->ra,
                         ra_tid->tid);
        } else if (skb->pkt_type == IEEE80211_SDATA_QUEUE_AGG_STOP) {
            ra_tid = (void *)&skb->cb;
            ieee80211_stop_tx_ba_cb(&sdata->vif, ra_tid->ra,
                        ra_tid->tid);
        } else if (ieee80211_is_action(mgmt->frame_control) &&
               mgmt->u.action.category == WLAN_CATEGORY_BACK) {
            int len = skb->len;

            mutex_lock(&local->sta_mtx);
            sta = sta_info_get_bss(sdata, mgmt->sa);
            if (sta) {
                switch (mgmt->u.action.u.addba_req.action_code) {
                case WLAN_ACTION_ADDBA_REQ:
                    ieee80211_process_addba_request(
                            local, sta, mgmt, len);
                    break;
                case WLAN_ACTION_ADDBA_RESP:
                    ieee80211_process_addba_resp(local, sta,
                                     mgmt, len);
                    break;
                case WLAN_ACTION_DELBA:
                    ieee80211_process_delba(sdata, sta,
                                mgmt, len);
                    break;
                default:
                    WARN_ON(1);
                    break;
                }
            }
            mutex_unlock(&local->sta_mtx);
        } else if (ieee80211_is_data_qos(mgmt->frame_control)) {
            struct ieee80211_hdr *hdr = (void *)mgmt;
            /*
             * So the frame isn't mgmt, but frame_control
             * is at the right place anyway, of course, so
             * the if statement is correct.
             *
             * Warn if we have other data frame types here,
             * they must not get here.
             */
            WARN_ON(hdr->frame_control &
                    cpu_to_le16(IEEE80211_STYPE_NULLFUNC));
            WARN_ON(!(hdr->seq_ctrl &
                    cpu_to_le16(IEEE80211_SCTL_FRAG)));
            /*
             * This was a fragment of a frame, received while
             * a block-ack session was active. That cannot be
             * right, so terminate the session.
             */
            mutex_lock(&local->sta_mtx);
            sta = sta_info_get_bss(sdata, mgmt->sa);
            if (sta) {
                u16 tid = *ieee80211_get_qos_ctl(hdr) &
                        IEEE80211_QOS_CTL_TID_MASK;

                __ieee80211_stop_rx_ba_session(
                    sta, tid, WLAN_BACK_RECIPIENT,
                    WLAN_REASON_QSTA_REQUIRE_SETUP,
                    true);
            }
            mutex_unlock(&local->sta_mtx);
        } else switch (sdata->vif.type) {
        case NL80211_IFTYPE_STATION:
            ieee80211_sta_rx_queued_mgmt(sdata, skb);
            break;
        case NL80211_IFTYPE_ADHOC:
            ieee80211_ibss_rx_queued_mgmt(sdata, skb);
            break;
        case NL80211_IFTYPE_MESH_POINT:
            if (!ieee80211_vif_is_mesh(&sdata->vif))
                break;
            ieee80211_mesh_rx_queued_mgmt(sdata, skb);
            break;
        default:
            WARN(1, "frame for unexpected interface type");
            break;
        }

        kfree_skb(skb);
    }

    /* then other type-dependent work */
    switch (sdata->vif.type) {
    case NL80211_IFTYPE_STATION:
        ieee80211_sta_work(sdata);
        break;
    case NL80211_IFTYPE_ADHOC:
        ieee80211_ibss_work(sdata);
        break;
    case NL80211_IFTYPE_MESH_POINT:
        if (!ieee80211_vif_is_mesh(&sdata->vif))
            break;
        ieee80211_mesh_work(sdata);
        break;
    default:
        break;
    }
}


/*
 * Helper function to initialise an interface to a specific type.
 */
static void ieee80211_setup_sdata(struct ieee80211_sub_if_data *sdata,
                  enum nl80211_iftype type)
{
    /* clear type-dependent union */
    memset(&sdata->u, 0, sizeof(sdata->u));

    /* and set some type-dependent values */
    sdata->vif.type = type;
    sdata->vif.p2p = false;
    sdata->wdev.iftype = type;

    sdata->control_port_protocol = cpu_to_be16(ETH_P_PAE);
    sdata->control_port_no_encrypt = false;

    sdata->noack_map = 0;

    /* only monitor/p2p-device differ */
    if (sdata->dev) {
        sdata->dev->netdev_ops = &ieee80211_dataif_ops;
        sdata->dev->type = ARPHRD_ETHER;
    }

    skb_queue_head_init(&sdata->skb_queue);
    INIT_WORK(&sdata->work, ieee80211_iface_work);

    switch (type) {
    case NL80211_IFTYPE_P2P_GO:
        type = NL80211_IFTYPE_AP;
        sdata->vif.type = type;
        sdata->vif.p2p = true;
        /* fall through */
    case NL80211_IFTYPE_AP:
        skb_queue_head_init(&sdata->u.ap.ps_bc_buf);
        INIT_LIST_HEAD(&sdata->u.ap.vlans);
        break;
    case NL80211_IFTYPE_P2P_CLIENT:
        type = NL80211_IFTYPE_STATION;
        sdata->vif.type = type;
        sdata->vif.p2p = true;
        /* fall through */
    case NL80211_IFTYPE_STATION:
        ieee80211_sta_setup_sdata(sdata);
        break;
    case NL80211_IFTYPE_ADHOC:
        ieee80211_ibss_setup_sdata(sdata);
        break;
    case NL80211_IFTYPE_MESH_POINT:
        if (ieee80211_vif_is_mesh(&sdata->vif))
            ieee80211_mesh_init_sdata(sdata);
        break;
    case NL80211_IFTYPE_MONITOR:
        sdata->dev->type = ARPHRD_IEEE80211_RADIOTAP;
        sdata->dev->netdev_ops = &ieee80211_monitorif_ops;
        sdata->u.mntr_flags = MONITOR_FLAG_CONTROL |
                      MONITOR_FLAG_OTHER_BSS;
        break;
    case NL80211_IFTYPE_WDS:
    case NL80211_IFTYPE_AP_VLAN:
    case NL80211_IFTYPE_P2P_DEVICE:
        break;
    case NL80211_IFTYPE_UNSPECIFIED:
    case NUM_NL80211_IFTYPES:
        BUG();
        break;
    }

    ieee80211_debugfs_add_netdev(sdata);
}

static int ieee80211_runtime_change_iftype(struct ieee80211_sub_if_data *sdata,
                       enum nl80211_iftype type)
{
    struct ieee80211_local *local = sdata->local;
    int ret, err;
    enum nl80211_iftype internal_type = type;
    bool p2p = false;

    ASSERT_RTNL();

    if (!local->ops->change_interface)
        return -EBUSY;

    switch (sdata->vif.type) {
    case NL80211_IFTYPE_AP:
    case NL80211_IFTYPE_STATION:
    case NL80211_IFTYPE_ADHOC:
        /*
         * Could maybe also all others here?
         * Just not sure how that interacts
         * with the RX/config path e.g. for
         * mesh.
         */
        break;
    default:
        return -EBUSY;
    }

    switch (type) {
    case NL80211_IFTYPE_AP:
    case NL80211_IFTYPE_STATION:
    case NL80211_IFTYPE_ADHOC:
        /*
         * Could probably support everything
         * but WDS here (WDS do_open can fail
         * under memory pressure, which this
         * code isn't prepared to handle).
         */
        break;
    case NL80211_IFTYPE_P2P_CLIENT:
        p2p = true;
        internal_type = NL80211_IFTYPE_STATION;
        break;
    case NL80211_IFTYPE_P2P_GO:
        p2p = true;
        internal_type = NL80211_IFTYPE_AP;
        break;
    default:
        return -EBUSY;
    }

    ret = ieee80211_check_concurrent_iface(sdata, internal_type);
    if (ret)
        return ret;

    ieee80211_do_stop(sdata, false);

    ieee80211_teardown_sdata(sdata);

    ret = drv_change_interface(local, sdata, internal_type, p2p);
    if (ret)
        type = sdata->vif.type;

    /*
     * Ignore return value here, there's not much we can do since
     * the driver changed the interface type internally already.
     * The warnings will hopefully make driver authors fix it :-)
     */
    ieee80211_check_queues(sdata);

    ieee80211_setup_sdata(sdata, type);

    err = ieee80211_do_open(&sdata->wdev, false);
    WARN(err, "type change: do_open returned %d", err);

    return ret;
}

int ieee80211_if_change_type(struct ieee80211_sub_if_data *sdata,
                 enum nl80211_iftype type)
{
    int ret;

    ASSERT_RTNL();

    if (type == ieee80211_vif_type_p2p(&sdata->vif))
        return 0;

    /* Setting ad-hoc mode on non-IBSS channel is not supported. */
    if (sdata->local->oper_channel->flags & IEEE80211_CHAN_NO_IBSS &&
        type == NL80211_IFTYPE_ADHOC)
        return -EOPNOTSUPP;

    if (ieee80211_sdata_running(sdata)) {
        ret = ieee80211_runtime_change_iftype(sdata, type);
        if (ret)
            return ret;
    } else {
        /* Purge and reset type-dependent state. */
        ieee80211_teardown_sdata(sdata);
        ieee80211_setup_sdata(sdata, type);
    }

    /* reset some values that shouldn't be kept across type changes */
    sdata->vif.bss_conf.basic_rates =
        ieee80211_mandatory_rates(sdata->local,
            sdata->local->oper_channel->band);
    sdata->drop_unencrypted = 0;
    if (type == NL80211_IFTYPE_STATION)
        sdata->u.mgd.use_4addr = false;

    return 0;
}

static void ieee80211_assign_perm_addr(struct ieee80211_local *local,
                       u8 *perm_addr, enum nl80211_iftype type)
{
    struct ieee80211_sub_if_data *sdata;
    u64 mask, start, addr, val, inc;
    u8 *m;
    u8 tmp_addr[ETH_ALEN];
    int i;

    /* default ... something at least */
    memcpy(perm_addr, local->hw.wiphy->perm_addr, ETH_ALEN);

    if (is_zero_ether_addr(local->hw.wiphy->addr_mask) &&
        local->hw.wiphy->n_addresses <= 1)
        return;

    mutex_lock(&local->iflist_mtx);

    switch (type) {
    case NL80211_IFTYPE_MONITOR:
        /* doesn't matter */
        break;
    case NL80211_IFTYPE_WDS:
    case NL80211_IFTYPE_AP_VLAN:
        /* match up with an AP interface */
        list_for_each_entry(sdata, &local->interfaces, list) {
            if (sdata->vif.type != NL80211_IFTYPE_AP)
                continue;
            memcpy(perm_addr, sdata->vif.addr, ETH_ALEN);
            break;
        }
        /* keep default if no AP interface present */
        break;
    case NL80211_IFTYPE_P2P_CLIENT:
    case NL80211_IFTYPE_P2P_GO:
        if (local->hw.flags & IEEE80211_HW_P2P_DEV_ADDR_FOR_INTF) {
            list_for_each_entry(sdata, &local->interfaces, list) {
                if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE)
                    continue;
                if (!ieee80211_sdata_running(sdata))
                    continue;
                memcpy(perm_addr, sdata->vif.addr, ETH_ALEN);
                goto out_unlock;
            }
        }
        /* otherwise fall through */
    default:
        /* assign a new address if possible -- try n_addresses first */
        for (i = 0; i < local->hw.wiphy->n_addresses; i++) {
            bool used = false;

            list_for_each_entry(sdata, &local->interfaces, list) {
                if (memcmp(local->hw.wiphy->addresses[i].addr,
                       sdata->vif.addr, ETH_ALEN) == 0) {
                    used = true;
                    break;
                }
            }

            if (!used) {
                memcpy(perm_addr,
                       local->hw.wiphy->addresses[i].addr,
                       ETH_ALEN);
                break;
            }
        }

        /* try mask if available */
        if (is_zero_ether_addr(local->hw.wiphy->addr_mask))
            break;

        m = local->hw.wiphy->addr_mask;
        mask =  ((u64)m[0] << 5*8) | ((u64)m[1] << 4*8) |
            ((u64)m[2] << 3*8) | ((u64)m[3] << 2*8) |
            ((u64)m[4] << 1*8) | ((u64)m[5] << 0*8);

        if (__ffs64(mask) + hweight64(mask) != fls64(mask)) {
            /* not a contiguous mask ... not handled now! */
            pr_info("not contiguous\n");
            break;
        }

        m = local->hw.wiphy->perm_addr;
        start = ((u64)m[0] << 5*8) | ((u64)m[1] << 4*8) |
            ((u64)m[2] << 3*8) | ((u64)m[3] << 2*8) |
            ((u64)m[4] << 1*8) | ((u64)m[5] << 0*8);

        inc = 1ULL<<__ffs64(mask);
        val = (start & mask);
        addr = (start & ~mask) | (val & mask);
        do {
            bool used = false;

            tmp_addr[5] = addr >> 0*8;
            tmp_addr[4] = addr >> 1*8;
            tmp_addr[3] = addr >> 2*8;
            tmp_addr[2] = addr >> 3*8;
            tmp_addr[1] = addr >> 4*8;
            tmp_addr[0] = addr >> 5*8;

            val += inc;

            list_for_each_entry(sdata, &local->interfaces, list) {
                if (memcmp(tmp_addr, sdata->vif.addr,
                            ETH_ALEN) == 0) {
                    used = true;
                    break;
                }
            }

            if (!used) {
                memcpy(perm_addr, tmp_addr, ETH_ALEN);
                break;
            }
            addr = (start & ~mask) | (val & mask);
        } while (addr != start);

        break;
    }

 out_unlock:
    mutex_unlock(&local->iflist_mtx);
}

int ieee80211_if_add(struct ieee80211_local *local, const char *name,
             struct wireless_dev **new_wdev, enum nl80211_iftype type,
             struct vif_params *params)
{
    struct net_device *ndev = NULL;
    struct ieee80211_sub_if_data *sdata = NULL;
    int ret, i;
    int txqs = 1;

    ASSERT_RTNL();

    if (type == NL80211_IFTYPE_P2P_DEVICE) {
        struct wireless_dev *wdev;

        sdata = kzalloc(sizeof(*sdata) + local->hw.vif_data_size,
                GFP_KERNEL);
        if (!sdata)
            return -ENOMEM;
        wdev = &sdata->wdev;

        sdata->dev = NULL;
        strlcpy(sdata->name, name, IFNAMSIZ);
        ieee80211_assign_perm_addr(local, wdev->address, type);
        memcpy(sdata->vif.addr, wdev->address, ETH_ALEN);
    } else {
        if (local->hw.queues >= IEEE80211_NUM_ACS)
            txqs = IEEE80211_NUM_ACS;

        ndev = alloc_netdev_mqs(sizeof(*sdata) +
                    local->hw.vif_data_size,
                    name, ieee80211_if_setup, txqs, 1);
        if (!ndev)
            return -ENOMEM;
        dev_net_set(ndev, wiphy_net(local->hw.wiphy));

        ndev->needed_headroom = local->tx_headroom +
                    4*6 /* four MAC addresses */
                    + 2 + 2 + 2 + 2 /* ctl, dur, seq, qos */
                    + 6 /* mesh */
                    + 8 /* rfc1042/bridge tunnel */
                    - ETH_HLEN /* ethernet hard_header_len */
                    + IEEE80211_ENCRYPT_HEADROOM;
        ndev->needed_tailroom = IEEE80211_ENCRYPT_TAILROOM;

        ret = dev_alloc_name(ndev, ndev->name);
        if (ret < 0) {
            free_netdev(ndev);
            return ret;
        }

        ieee80211_assign_perm_addr(local, ndev->perm_addr, type);
        memcpy(ndev->dev_addr, ndev->perm_addr, ETH_ALEN);
        SET_NETDEV_DEV(ndev, wiphy_dev(local->hw.wiphy));

        /* don't use IEEE80211_DEV_TO_SUB_IF -- it checks too much */
        sdata = netdev_priv(ndev);
        ndev->ieee80211_ptr = &sdata->wdev;
        memcpy(sdata->vif.addr, ndev->dev_addr, ETH_ALEN);
        memcpy(sdata->name, ndev->name, IFNAMSIZ);

        sdata->dev = ndev;
    }

    /* initialise type-independent data */
    sdata->wdev.wiphy = local->hw.wiphy;
    sdata->local = local;
#ifdef CONFIG_INET
    sdata->arp_filter_state = true;
#endif

    for (i = 0; i < IEEE80211_FRAGMENT_MAX; i++)
        skb_queue_head_init(&sdata->fragments[i].skb_list);

    INIT_LIST_HEAD(&sdata->key_list);

    for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
        struct ieee80211_supported_band *sband;
        sband = local->hw.wiphy->bands[i];
        sdata->rc_rateidx_mask[i] =
            sband ? (1 << sband->n_bitrates) - 1 : 0;
        if (sband)
            memcpy(sdata->rc_rateidx_mcs_mask[i],
                   sband->ht_cap.mcs.rx_mask,
                   sizeof(sdata->rc_rateidx_mcs_mask[i]));
        else
            memset(sdata->rc_rateidx_mcs_mask[i], 0,
                   sizeof(sdata->rc_rateidx_mcs_mask[i]));
    }

    ieee80211_set_default_queues(sdata);

    /* setup type-dependent data */
    ieee80211_setup_sdata(sdata, type);

    if (ndev) {
        if (params) {
            ndev->ieee80211_ptr->use_4addr = params->use_4addr;
            if (type == NL80211_IFTYPE_STATION)
                sdata->u.mgd.use_4addr = params->use_4addr;
        }

        ndev->features |= local->hw.netdev_features;

        ret = register_netdevice(ndev);
        if (ret) {
            free_netdev(ndev);
            return ret;
        }
    }

    mutex_lock(&local->iflist_mtx);
    list_add_tail_rcu(&sdata->list, &local->interfaces);
    mutex_unlock(&local->iflist_mtx);

    if (new_wdev)
        *new_wdev = &sdata->wdev;

    return 0;
}

void ieee80211_if_remove(struct ieee80211_sub_if_data *sdata)
{
    ASSERT_RTNL();

    mutex_lock(&sdata->local->iflist_mtx);
    list_del_rcu(&sdata->list);
    mutex_unlock(&sdata->local->iflist_mtx);

    synchronize_rcu();

    if (sdata->dev) {
        unregister_netdevice(sdata->dev);
    } else {
        cfg80211_unregister_wdev(&sdata->wdev);
        kfree(sdata);
    }
}

void ieee80211_sdata_stop(struct ieee80211_sub_if_data *sdata)
{
    if (WARN_ON_ONCE(!test_bit(SDATA_STATE_RUNNING, &sdata->state)))
        return;
    ieee80211_do_stop(sdata, true);
    ieee80211_teardown_sdata(sdata);
}

/*
 * Remove all interfaces, may only be called at hardware unregistration
 * time because it doesn't do RCU-safe list removals.
 */
void ieee80211_remove_interfaces(struct ieee80211_local *local)
{
    struct ieee80211_sub_if_data *sdata, *tmp;
    LIST_HEAD(unreg_list);
    LIST_HEAD(wdev_list);

    ASSERT_RTNL();

    mutex_lock(&local->iflist_mtx);
    list_for_each_entry_safe(sdata, tmp, &local->interfaces, list) {
        list_del(&sdata->list);

        if (sdata->dev)
            unregister_netdevice_queue(sdata->dev, &unreg_list);
        else
            list_add(&sdata->list, &wdev_list);
    }
    mutex_unlock(&local->iflist_mtx);
    unregister_netdevice_many(&unreg_list);
    list_del(&unreg_list);

    list_for_each_entry_safe(sdata, tmp, &wdev_list, list) {
        list_del(&sdata->list);
        cfg80211_unregister_wdev(&sdata->wdev);
        kfree(sdata);
    }
}

static int netdev_notify(struct notifier_block *nb,
             unsigned long state,
             void *ndev)
{
    struct net_device *dev = ndev;
    struct ieee80211_sub_if_data *sdata;

    if (state != NETDEV_CHANGENAME)
        return 0;

    if (!dev->ieee80211_ptr || !dev->ieee80211_ptr->wiphy)
        return 0;

    if (dev->ieee80211_ptr->wiphy->privid != mac80211_wiphy_privid)
        return 0;

    sdata = IEEE80211_DEV_TO_SUB_IF(dev);

    memcpy(sdata->name, dev->name, IFNAMSIZ);

    ieee80211_debugfs_rename_netdev(sdata);
    return 0;
}

static struct notifier_block mac80211_netdev_notifier = {
    .notifier_call = netdev_notify,
};

int ieee80211_iface_init(void)
{
    return register_netdevice_notifier(&mac80211_netdev_notifier);
}

void ieee80211_iface_exit(void)
{
    unregister_netdevice_notifier(&mac80211_netdev_notifier);
}