core.c

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/*
 * This is the linux wireless configuration interface.
 *
 * Copyright 2006-2010      Johannes Berg <[email protected]>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/if.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/nl80211.h>
#include <linux/debugfs.h>
#include <linux/notifier.h>
#include <linux/device.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <linux/sched.h>
#include <net/genetlink.h>
#include <net/cfg80211.h>
#include "nl80211.h"
#include "core.h"
#include "sysfs.h"
#include "debugfs.h"
#include "wext-compat.h"
#include "ethtool.h"

/* name for sysfs, %d is appended */
#define PHY_NAME "phy"

MODULE_AUTHOR("Johannes Berg");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("wireless configuration support");

/* RCU-protected (and cfg80211_mutex for writers) */
LIST_HEAD(cfg80211_rdev_list);
int cfg80211_rdev_list_generation;

DEFINE_MUTEX(cfg80211_mutex);

/* for debugfs */
static struct dentry *ieee80211_debugfs_dir;

/* for the cleanup, scan and event works */
struct workqueue_struct *cfg80211_wq;

static bool cfg80211_disable_40mhz_24ghz;
module_param(cfg80211_disable_40mhz_24ghz, bool, 0644);
MODULE_PARM_DESC(cfg80211_disable_40mhz_24ghz,
         "Disable 40MHz support in the 2.4GHz band");

/* requires cfg80211_mutex to be held! */
struct cfg80211_registered_device *cfg80211_rdev_by_wiphy_idx(int wiphy_idx)
{
    struct cfg80211_registered_device *result = NULL, *rdev;

    if (!wiphy_idx_valid(wiphy_idx))
        return NULL;

    assert_cfg80211_lock();

    list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
        if (rdev->wiphy_idx == wiphy_idx) {
            result = rdev;
            break;
        }
    }

    return result;
}

int get_wiphy_idx(struct wiphy *wiphy)
{
    struct cfg80211_registered_device *rdev;
    if (!wiphy)
        return WIPHY_IDX_STALE;
    rdev = wiphy_to_dev(wiphy);
    return rdev->wiphy_idx;
}

/* requires cfg80211_rdev_mutex to be held! */
struct wiphy *wiphy_idx_to_wiphy(int wiphy_idx)
{
    struct cfg80211_registered_device *rdev;

    if (!wiphy_idx_valid(wiphy_idx))
        return NULL;

    assert_cfg80211_lock();

    rdev = cfg80211_rdev_by_wiphy_idx(wiphy_idx);
    if (!rdev)
        return NULL;
    return &rdev->wiphy;
}

struct cfg80211_registered_device *
cfg80211_get_dev_from_ifindex(struct net *net, int ifindex)
{
    struct cfg80211_registered_device *rdev = ERR_PTR(-ENODEV);
    struct net_device *dev;

    mutex_lock(&cfg80211_mutex);
    dev = dev_get_by_index(net, ifindex);
    if (!dev)
        goto out;
    if (dev->ieee80211_ptr) {
        rdev = wiphy_to_dev(dev->ieee80211_ptr->wiphy);
        mutex_lock(&rdev->mtx);
    } else
        rdev = ERR_PTR(-ENODEV);
    dev_put(dev);
 out:
    mutex_unlock(&cfg80211_mutex);
    return rdev;
}

/* requires cfg80211_mutex to be held */
int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,
            char *newname)
{
    struct cfg80211_registered_device *rdev2;
    int wiphy_idx, taken = -1, result, digits;

    assert_cfg80211_lock();

    /* prohibit calling the thing phy%d when %d is not its number */
    sscanf(newname, PHY_NAME "%d%n", &wiphy_idx, &taken);
    if (taken == strlen(newname) && wiphy_idx != rdev->wiphy_idx) {
        /* count number of places needed to print wiphy_idx */
        digits = 1;
        while (wiphy_idx /= 10)
            digits++;
        /*
         * deny the name if it is phy<idx> where <idx> is printed
         * without leading zeroes. taken == strlen(newname) here
         */
        if (taken == strlen(PHY_NAME) + digits)
            return -EINVAL;
    }


    /* Ignore nop renames */
    if (strcmp(newname, dev_name(&rdev->wiphy.dev)) == 0)
        return 0;

    /* Ensure another device does not already have this name. */
    list_for_each_entry(rdev2, &cfg80211_rdev_list, list)
        if (strcmp(newname, dev_name(&rdev2->wiphy.dev)) == 0)
            return -EINVAL;

    result = device_rename(&rdev->wiphy.dev, newname);
    if (result)
        return result;

    if (rdev->wiphy.debugfsdir &&
        !debugfs_rename(rdev->wiphy.debugfsdir->d_parent,
                rdev->wiphy.debugfsdir,
                rdev->wiphy.debugfsdir->d_parent,
                newname))
        pr_err("failed to rename debugfs dir to %s!\n", newname);

    nl80211_notify_dev_rename(rdev);

    return 0;
}

int cfg80211_switch_netns(struct cfg80211_registered_device *rdev,
              struct net *net)
{
    struct wireless_dev *wdev;
    int err = 0;

    if (!(rdev->wiphy.flags & WIPHY_FLAG_NETNS_OK))
        return -EOPNOTSUPP;

    list_for_each_entry(wdev, &rdev->wdev_list, list) {
        if (!wdev->netdev)
            continue;
        wdev->netdev->features &= ~NETIF_F_NETNS_LOCAL;
        err = dev_change_net_namespace(wdev->netdev, net, "wlan%d");
        if (err)
            break;
        wdev->netdev->features |= NETIF_F_NETNS_LOCAL;
    }

    if (err) {
        /* failed -- clean up to old netns */
        net = wiphy_net(&rdev->wiphy);

        list_for_each_entry_continue_reverse(wdev, &rdev->wdev_list,
                             list) {
            if (!wdev->netdev)
                continue;
            wdev->netdev->features &= ~NETIF_F_NETNS_LOCAL;
            err = dev_change_net_namespace(wdev->netdev, net,
                            "wlan%d");
            WARN_ON(err);
            wdev->netdev->features |= NETIF_F_NETNS_LOCAL;
        }

        return err;
    }

    wiphy_net_set(&rdev->wiphy, net);

    err = device_rename(&rdev->wiphy.dev, dev_name(&rdev->wiphy.dev));
    WARN_ON(err);

    return 0;
}

static void cfg80211_rfkill_poll(struct rfkill *rfkill, void *data)
{
    struct cfg80211_registered_device *rdev = data;

    rdev->ops->rfkill_poll(&rdev->wiphy);
}

static int cfg80211_rfkill_set_block(void *data, bool blocked)
{
    struct cfg80211_registered_device *rdev = data;
    struct wireless_dev *wdev;

    if (!blocked)
        return 0;

    rtnl_lock();
    mutex_lock(&rdev->devlist_mtx);

    list_for_each_entry(wdev, &rdev->wdev_list, list) {
        if (wdev->netdev) {
            dev_close(wdev->netdev);
            continue;
        }
        /* otherwise, check iftype */
        switch (wdev->iftype) {
        case NL80211_IFTYPE_P2P_DEVICE:
            if (!wdev->p2p_started)
                break;
            rdev->ops->stop_p2p_device(&rdev->wiphy, wdev);
            wdev->p2p_started = false;
            rdev->opencount--;
            break;
        default:
            break;
        }
    }

    mutex_unlock(&rdev->devlist_mtx);
    rtnl_unlock();

    return 0;
}

static void cfg80211_rfkill_sync_work(struct work_struct *work)
{
    struct cfg80211_registered_device *rdev;

    rdev = container_of(work, struct cfg80211_registered_device, rfkill_sync);
    cfg80211_rfkill_set_block(rdev, rfkill_blocked(rdev->rfkill));
}

static void cfg80211_event_work(struct work_struct *work)
{
    struct cfg80211_registered_device *rdev;

    rdev = container_of(work, struct cfg80211_registered_device,
                event_work);

    rtnl_lock();
    cfg80211_lock_rdev(rdev);

    cfg80211_process_rdev_events(rdev);
    cfg80211_unlock_rdev(rdev);
    rtnl_unlock();
}

/* exported functions */

struct wiphy *wiphy_new(const struct cfg80211_ops *ops, int sizeof_priv)
{
    static int wiphy_counter;

    struct cfg80211_registered_device *rdev;
    int alloc_size;

    WARN_ON(ops->add_key && (!ops->del_key || !ops->set_default_key));
    WARN_ON(ops->auth && (!ops->assoc || !ops->deauth || !ops->disassoc));
    WARN_ON(ops->connect && !ops->disconnect);
    WARN_ON(ops->join_ibss && !ops->leave_ibss);
    WARN_ON(ops->add_virtual_intf && !ops->del_virtual_intf);
    WARN_ON(ops->add_station && !ops->del_station);
    WARN_ON(ops->add_mpath && !ops->del_mpath);
    WARN_ON(ops->join_mesh && !ops->leave_mesh);

    alloc_size = sizeof(*rdev) + sizeof_priv;

    rdev = kzalloc(alloc_size, GFP_KERNEL);
    if (!rdev)
        return NULL;

    rdev->ops = ops;

    mutex_lock(&cfg80211_mutex);

    rdev->wiphy_idx = wiphy_counter++;

    if (unlikely(!wiphy_idx_valid(rdev->wiphy_idx))) {
        wiphy_counter--;
        mutex_unlock(&cfg80211_mutex);
        /* ugh, wrapped! */
        kfree(rdev);
        return NULL;
    }

    mutex_unlock(&cfg80211_mutex);

    /* give it a proper name */
    dev_set_name(&rdev->wiphy.dev, PHY_NAME "%d", rdev->wiphy_idx);

    mutex_init(&rdev->mtx);
    mutex_init(&rdev->devlist_mtx);
    mutex_init(&rdev->sched_scan_mtx);
    INIT_LIST_HEAD(&rdev->wdev_list);
    spin_lock_init(&rdev->bss_lock);
    INIT_LIST_HEAD(&rdev->bss_list);
    INIT_WORK(&rdev->scan_done_wk, __cfg80211_scan_done);
    INIT_WORK(&rdev->sched_scan_results_wk, __cfg80211_sched_scan_results);
#ifdef CONFIG_CFG80211_WEXT
    rdev->wiphy.wext = &cfg80211_wext_handler;
#endif

    device_initialize(&rdev->wiphy.dev);
    rdev->wiphy.dev.class = &ieee80211_class;
    rdev->wiphy.dev.platform_data = rdev;

#ifdef CONFIG_CFG80211_DEFAULT_PS
    rdev->wiphy.flags |= WIPHY_FLAG_PS_ON_BY_DEFAULT;
#endif

    wiphy_net_set(&rdev->wiphy, &init_net);

    rdev->rfkill_ops.set_block = cfg80211_rfkill_set_block;
    rdev->rfkill = rfkill_alloc(dev_name(&rdev->wiphy.dev),
                   &rdev->wiphy.dev, RFKILL_TYPE_WLAN,
                   &rdev->rfkill_ops, rdev);

    if (!rdev->rfkill) {
        kfree(rdev);
        return NULL;
    }

    INIT_WORK(&rdev->rfkill_sync, cfg80211_rfkill_sync_work);
    INIT_WORK(&rdev->conn_work, cfg80211_conn_work);
    INIT_WORK(&rdev->event_work, cfg80211_event_work);

    init_waitqueue_head(&rdev->dev_wait);

    /*
     * Initialize wiphy parameters to IEEE 802.11 MIB default values.
     * Fragmentation and RTS threshold are disabled by default with the
     * special -1 value.
     */
    rdev->wiphy.retry_short = 7;
    rdev->wiphy.retry_long = 4;
    rdev->wiphy.frag_threshold = (u32) -1;
    rdev->wiphy.rts_threshold = (u32) -1;
    rdev->wiphy.coverage_class = 0;

    return &rdev->wiphy;
}
EXPORT_SYMBOL(wiphy_new);

static int wiphy_verify_combinations(struct wiphy *wiphy)
{
    const struct ieee80211_iface_combination *c;
    int i, j;

    for (i = 0; i < wiphy->n_iface_combinations; i++) {
        u32 cnt = 0;
        u16 all_iftypes = 0;

        c = &wiphy->iface_combinations[i];

        /* Combinations with just one interface aren't real */
        if (WARN_ON(c->max_interfaces < 2))
            return -EINVAL;

        /* Need at least one channel */
        if (WARN_ON(!c->num_different_channels))
            return -EINVAL;

        /*
         * Put a sane limit on maximum number of different
         * channels to simplify channel accounting code.
         */
        if (WARN_ON(c->num_different_channels >
                CFG80211_MAX_NUM_DIFFERENT_CHANNELS))
            return -EINVAL;

        if (WARN_ON(!c->n_limits))
            return -EINVAL;

        for (j = 0; j < c->n_limits; j++) {
            u16 types = c->limits[j].types;

            /*
             * interface types shouldn't overlap, this is
             * used in cfg80211_can_change_interface()
             */
            if (WARN_ON(types & all_iftypes))
                return -EINVAL;
            all_iftypes |= types;

            if (WARN_ON(!c->limits[j].max))
                return -EINVAL;

            /* Shouldn't list software iftypes in combinations! */
            if (WARN_ON(wiphy->software_iftypes & types))
                return -EINVAL;

            /* Only a single P2P_DEVICE can be allowed */
            if (WARN_ON(types & BIT(NL80211_IFTYPE_P2P_DEVICE) &&
                    c->limits[j].max > 1))
                return -EINVAL;

            cnt += c->limits[j].max;
            /*
             * Don't advertise an unsupported type
             * in a combination.
             */
            if (WARN_ON((wiphy->interface_modes & types) != types))
                return -EINVAL;
        }

        /* You can't even choose that many! */
        if (WARN_ON(cnt < c->max_interfaces))
            return -EINVAL;
    }

    return 0;
}

int wiphy_register(struct wiphy *wiphy)
{
    struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
    int res;
    enum ieee80211_band band;
    struct ieee80211_supported_band *sband;
    bool have_band = false;
    int i;
    u16 ifmodes = wiphy->interface_modes;

#ifdef CONFIG_PM
    if (WARN_ON((wiphy->wowlan.flags & WIPHY_WOWLAN_GTK_REKEY_FAILURE) &&
            !(wiphy->wowlan.flags & WIPHY_WOWLAN_SUPPORTS_GTK_REKEY)))
        return -EINVAL;
#endif

    if (WARN_ON(wiphy->ap_sme_capa &&
            !(wiphy->flags & WIPHY_FLAG_HAVE_AP_SME)))
        return -EINVAL;

    if (WARN_ON(wiphy->addresses && !wiphy->n_addresses))
        return -EINVAL;

    if (WARN_ON(wiphy->addresses &&
            !is_zero_ether_addr(wiphy->perm_addr) &&
            memcmp(wiphy->perm_addr, wiphy->addresses[0].addr,
               ETH_ALEN)))
        return -EINVAL;

    if (wiphy->addresses)
        memcpy(wiphy->perm_addr, wiphy->addresses[0].addr, ETH_ALEN);

    /* sanity check ifmodes */
    WARN_ON(!ifmodes);
    ifmodes &= ((1 << NUM_NL80211_IFTYPES) - 1) & ~1;
    if (WARN_ON(ifmodes != wiphy->interface_modes))
        wiphy->interface_modes = ifmodes;

    res = wiphy_verify_combinations(wiphy);
    if (res)
        return res;

    /* sanity check supported bands/channels */
    for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
        sband = wiphy->bands[band];
        if (!sband)
            continue;

        sband->band = band;
        if (WARN_ON(!sband->n_channels))
            return -EINVAL;
        /*
         * on 60gHz band, there are no legacy rates, so
         * n_bitrates is 0
         */
        if (WARN_ON(band != IEEE80211_BAND_60GHZ &&
                !sband->n_bitrates))
            return -EINVAL;

        /*
         * Since cfg80211_disable_40mhz_24ghz is global, we can
         * modify the sband's ht data even if the driver uses a
         * global structure for that.
         */
        if (cfg80211_disable_40mhz_24ghz &&
            band == IEEE80211_BAND_2GHZ &&
            sband->ht_cap.ht_supported) {
            sband->ht_cap.cap &= ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
            sband->ht_cap.cap &= ~IEEE80211_HT_CAP_SGI_40;
        }

        /*
         * Since we use a u32 for rate bitmaps in
         * ieee80211_get_response_rate, we cannot
         * have more than 32 legacy rates.
         */
        if (WARN_ON(sband->n_bitrates > 32))
            return -EINVAL;

        for (i = 0; i < sband->n_channels; i++) {
            sband->channels[i].orig_flags =
                sband->channels[i].flags;
            sband->channels[i].orig_mag = INT_MAX;
            sband->channels[i].orig_mpwr =
                sband->channels[i].max_power;
            sband->channels[i].band = band;
        }

        have_band = true;
    }

    if (!have_band) {
        WARN_ON(1);
        return -EINVAL;
    }

#ifdef CONFIG_PM
    if (rdev->wiphy.wowlan.n_patterns) {
        if (WARN_ON(!rdev->wiphy.wowlan.pattern_min_len ||
                rdev->wiphy.wowlan.pattern_min_len >
                rdev->wiphy.wowlan.pattern_max_len))
            return -EINVAL;
    }
#endif

    /* check and set up bitrates */
    ieee80211_set_bitrate_flags(wiphy);

    mutex_lock(&cfg80211_mutex);

    res = device_add(&rdev->wiphy.dev);
    if (res) {
        mutex_unlock(&cfg80211_mutex);
        return res;
    }

    /* set up regulatory info */
    wiphy_regulatory_register(wiphy);

    list_add_rcu(&rdev->list, &cfg80211_rdev_list);
    cfg80211_rdev_list_generation++;

    /* add to debugfs */
    rdev->wiphy.debugfsdir =
        debugfs_create_dir(wiphy_name(&rdev->wiphy),
                   ieee80211_debugfs_dir);
    if (IS_ERR(rdev->wiphy.debugfsdir))
        rdev->wiphy.debugfsdir = NULL;

    if (wiphy->flags & WIPHY_FLAG_CUSTOM_REGULATORY) {
        struct regulatory_request request;

        request.wiphy_idx = get_wiphy_idx(wiphy);
        request.initiator = NL80211_REGDOM_SET_BY_DRIVER;
        request.alpha2[0] = '9';
        request.alpha2[1] = '9';

        nl80211_send_reg_change_event(&request);
    }

    cfg80211_debugfs_rdev_add(rdev);
    mutex_unlock(&cfg80211_mutex);

    /*
     * due to a locking dependency this has to be outside of the
     * cfg80211_mutex lock
     */
    res = rfkill_register(rdev->rfkill);
    if (res)
        goto out_rm_dev;

    rtnl_lock();
    rdev->wiphy.registered = true;
    rtnl_unlock();
    return 0;

out_rm_dev:
    device_del(&rdev->wiphy.dev);
    return res;
}
EXPORT_SYMBOL(wiphy_register);

void wiphy_rfkill_start_polling(struct wiphy *wiphy)
{
    struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);

    if (!rdev->ops->rfkill_poll)
        return;
    rdev->rfkill_ops.poll = cfg80211_rfkill_poll;
    rfkill_resume_polling(rdev->rfkill);
}
EXPORT_SYMBOL(wiphy_rfkill_start_polling);

void wiphy_rfkill_stop_polling(struct wiphy *wiphy)
{
    struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);

    rfkill_pause_polling(rdev->rfkill);
}
EXPORT_SYMBOL(wiphy_rfkill_stop_polling);

void wiphy_unregister(struct wiphy *wiphy)
{
    struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);

    rtnl_lock();
    rdev->wiphy.registered = false;
    rtnl_unlock();

    rfkill_unregister(rdev->rfkill);

    /* protect the device list */
    mutex_lock(&cfg80211_mutex);

    wait_event(rdev->dev_wait, ({
        int __count;
        mutex_lock(&rdev->devlist_mtx);
        __count = rdev->opencount;
        mutex_unlock(&rdev->devlist_mtx);
        __count == 0; }));

    mutex_lock(&rdev->devlist_mtx);
    BUG_ON(!list_empty(&rdev->wdev_list));
    mutex_unlock(&rdev->devlist_mtx);

    /*
     * First remove the hardware from everywhere, this makes
     * it impossible to find from userspace.
     */
    debugfs_remove_recursive(rdev->wiphy.debugfsdir);
    list_del_rcu(&rdev->list);
    synchronize_rcu();

    /*
     * Try to grab rdev->mtx. If a command is still in progress,
     * hopefully the driver will refuse it since it's tearing
     * down the device already. We wait for this command to complete
     * before unlinking the item from the list.
     * Note: as codified by the BUG_ON above we cannot get here if
     * a virtual interface is still present. Hence, we can only get
     * to lock contention here if userspace issues a command that
     * identified the hardware by wiphy index.
     */
    cfg80211_lock_rdev(rdev);
    /* nothing */
    cfg80211_unlock_rdev(rdev);

    /*
     * If this device got a regulatory hint tell core its
     * free to listen now to a new shiny device regulatory hint
     */
    wiphy_regulatory_deregister(wiphy);

    cfg80211_rdev_list_generation++;
    device_del(&rdev->wiphy.dev);

    mutex_unlock(&cfg80211_mutex);

    flush_work(&rdev->scan_done_wk);
    cancel_work_sync(&rdev->conn_work);
    flush_work(&rdev->event_work);

    if (rdev->wowlan && rdev->ops->set_wakeup)
        rdev->ops->set_wakeup(&rdev->wiphy, false);
    cfg80211_rdev_free_wowlan(rdev);
}
EXPORT_SYMBOL(wiphy_unregister);

void cfg80211_dev_free(struct cfg80211_registered_device *rdev)
{
    struct cfg80211_internal_bss *scan, *tmp;
    rfkill_destroy(rdev->rfkill);
    mutex_destroy(&rdev->mtx);
    mutex_destroy(&rdev->devlist_mtx);
    mutex_destroy(&rdev->sched_scan_mtx);
    list_for_each_entry_safe(scan, tmp, &rdev->bss_list, list)
        cfg80211_put_bss(&scan->pub);
    kfree(rdev);
}

void wiphy_free(struct wiphy *wiphy)
{
    put_device(&wiphy->dev);
}
EXPORT_SYMBOL(wiphy_free);

void wiphy_rfkill_set_hw_state(struct wiphy *wiphy, bool blocked)
{
    struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);

    if (rfkill_set_hw_state(rdev->rfkill, blocked))
        schedule_work(&rdev->rfkill_sync);
}
EXPORT_SYMBOL(wiphy_rfkill_set_hw_state);

static void wdev_cleanup_work(struct work_struct *work)
{
    struct wireless_dev *wdev;
    struct cfg80211_registered_device *rdev;

    wdev = container_of(work, struct wireless_dev, cleanup_work);
    rdev = wiphy_to_dev(wdev->wiphy);

    cfg80211_lock_rdev(rdev);

    if (WARN_ON(rdev->scan_req && rdev->scan_req->wdev == wdev)) {
        rdev->scan_req->aborted = true;
        ___cfg80211_scan_done(rdev, true);
    }

    cfg80211_unlock_rdev(rdev);

    mutex_lock(&rdev->sched_scan_mtx);

    if (WARN_ON(rdev->sched_scan_req &&
            rdev->sched_scan_req->dev == wdev->netdev)) {
        __cfg80211_stop_sched_scan(rdev, false);
    }

    mutex_unlock(&rdev->sched_scan_mtx);

    mutex_lock(&rdev->devlist_mtx);
    rdev->opencount--;
    mutex_unlock(&rdev->devlist_mtx);
    wake_up(&rdev->dev_wait);

    dev_put(wdev->netdev);
}

void cfg80211_unregister_wdev(struct wireless_dev *wdev)
{
    struct cfg80211_registered_device *rdev = wiphy_to_dev(wdev->wiphy);

    ASSERT_RTNL();

    if (WARN_ON(wdev->netdev))
        return;

    mutex_lock(&rdev->devlist_mtx);
    list_del_rcu(&wdev->list);
    rdev->devlist_generation++;

    switch (wdev->iftype) {
    case NL80211_IFTYPE_P2P_DEVICE:
        if (!wdev->p2p_started)
            break;
        rdev->ops->stop_p2p_device(&rdev->wiphy, wdev);
        wdev->p2p_started = false;
        rdev->opencount--;
        break;
    default:
        WARN_ON_ONCE(1);
        break;
    }
    mutex_unlock(&rdev->devlist_mtx);
}
EXPORT_SYMBOL(cfg80211_unregister_wdev);

static struct device_type wiphy_type = {
    .name   = "wlan",
};

void cfg80211_update_iface_num(struct cfg80211_registered_device *rdev,
                   enum nl80211_iftype iftype, int num)
{
    ASSERT_RTNL();

    rdev->num_running_ifaces += num;
    if (iftype == NL80211_IFTYPE_MONITOR)
        rdev->num_running_monitor_ifaces += num;
}

static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
                     unsigned long state,
                     void *ndev)
{
    struct net_device *dev = ndev;
    struct wireless_dev *wdev = dev->ieee80211_ptr;
    struct cfg80211_registered_device *rdev;
    int ret;

    if (!wdev)
        return NOTIFY_DONE;

    rdev = wiphy_to_dev(wdev->wiphy);

    WARN_ON(wdev->iftype == NL80211_IFTYPE_UNSPECIFIED);

    switch (state) {
    case NETDEV_POST_INIT:
        SET_NETDEV_DEVTYPE(dev, &wiphy_type);
        break;
    case NETDEV_REGISTER:
        /*
         * NB: cannot take rdev->mtx here because this may be
         * called within code protected by it when interfaces
         * are added with nl80211.
         */
        mutex_init(&wdev->mtx);
        INIT_WORK(&wdev->cleanup_work, wdev_cleanup_work);
        INIT_LIST_HEAD(&wdev->event_list);
        spin_lock_init(&wdev->event_lock);
        INIT_LIST_HEAD(&wdev->mgmt_registrations);
        spin_lock_init(&wdev->mgmt_registrations_lock);

        mutex_lock(&rdev->devlist_mtx);
        wdev->identifier = ++rdev->wdev_id;
        list_add_rcu(&wdev->list, &rdev->wdev_list);
        rdev->devlist_generation++;
        /* can only change netns with wiphy */
        dev->features |= NETIF_F_NETNS_LOCAL;

        if (sysfs_create_link(&dev->dev.kobj, &rdev->wiphy.dev.kobj,
                      "phy80211")) {
            pr_err("failed to add phy80211 symlink to netdev!\n");
        }
        wdev->netdev = dev;
        wdev->sme_state = CFG80211_SME_IDLE;
        mutex_unlock(&rdev->devlist_mtx);
#ifdef CONFIG_CFG80211_WEXT
        wdev->wext.default_key = -1;
        wdev->wext.default_mgmt_key = -1;
        wdev->wext.connect.auth_type = NL80211_AUTHTYPE_AUTOMATIC;
#endif

        if (wdev->wiphy->flags & WIPHY_FLAG_PS_ON_BY_DEFAULT)
            wdev->ps = true;
        else
            wdev->ps = false;
        /* allow mac80211 to determine the timeout */
        wdev->ps_timeout = -1;

        if (!dev->ethtool_ops)
            dev->ethtool_ops = &cfg80211_ethtool_ops;

        if ((wdev->iftype == NL80211_IFTYPE_STATION ||
             wdev->iftype == NL80211_IFTYPE_P2P_CLIENT ||
             wdev->iftype == NL80211_IFTYPE_ADHOC) && !wdev->use_4addr)
            dev->priv_flags |= IFF_DONT_BRIDGE;
        break;
    case NETDEV_GOING_DOWN:
        switch (wdev->iftype) {
        case NL80211_IFTYPE_ADHOC:
            cfg80211_leave_ibss(rdev, dev, true);
            break;
        case NL80211_IFTYPE_P2P_CLIENT:
        case NL80211_IFTYPE_STATION:
            mutex_lock(&rdev->sched_scan_mtx);
            __cfg80211_stop_sched_scan(rdev, false);
            mutex_unlock(&rdev->sched_scan_mtx);

            wdev_lock(wdev);
#ifdef CONFIG_CFG80211_WEXT
            kfree(wdev->wext.ie);
            wdev->wext.ie = NULL;
            wdev->wext.ie_len = 0;
            wdev->wext.connect.auth_type = NL80211_AUTHTYPE_AUTOMATIC;
#endif
            __cfg80211_disconnect(rdev, dev,
                          WLAN_REASON_DEAUTH_LEAVING, true);
            cfg80211_mlme_down(rdev, dev);
            wdev_unlock(wdev);
            break;
        case NL80211_IFTYPE_MESH_POINT:
            cfg80211_leave_mesh(rdev, dev);
            break;
        case NL80211_IFTYPE_AP:
            cfg80211_stop_ap(rdev, dev);
            break;
        default:
            break;
        }
        wdev->beacon_interval = 0;
        break;
    case NETDEV_DOWN:
        cfg80211_update_iface_num(rdev, wdev->iftype, -1);
        dev_hold(dev);
        queue_work(cfg80211_wq, &wdev->cleanup_work);
        break;
    case NETDEV_UP:
        /*
         * If we have a really quick DOWN/UP succession we may
         * have this work still pending ... cancel it and see
         * if it was pending, in which case we need to account
         * for some of the work it would have done.
         */
        if (cancel_work_sync(&wdev->cleanup_work)) {
            mutex_lock(&rdev->devlist_mtx);
            rdev->opencount--;
            mutex_unlock(&rdev->devlist_mtx);
            dev_put(dev);
        }
        cfg80211_update_iface_num(rdev, wdev->iftype, 1);
        cfg80211_lock_rdev(rdev);
        mutex_lock(&rdev->devlist_mtx);
        wdev_lock(wdev);
        switch (wdev->iftype) {
#ifdef CONFIG_CFG80211_WEXT
        case NL80211_IFTYPE_ADHOC:
            cfg80211_ibss_wext_join(rdev, wdev);
            break;
        case NL80211_IFTYPE_STATION:
            cfg80211_mgd_wext_connect(rdev, wdev);
            break;
#endif
#ifdef CONFIG_MAC80211_MESH
        case NL80211_IFTYPE_MESH_POINT:
            {
                /* backward compat code... */
                struct mesh_setup setup;
                memcpy(&setup, &default_mesh_setup,
                        sizeof(setup));
                 /* back compat only needed for mesh_id */
                setup.mesh_id = wdev->ssid;
                setup.mesh_id_len = wdev->mesh_id_up_len;
                if (wdev->mesh_id_up_len)
                    __cfg80211_join_mesh(rdev, dev,
                            &setup,
                            &default_mesh_config);
                break;
            }
#endif
        default:
            break;
        }
        wdev_unlock(wdev);
        rdev->opencount++;
        mutex_unlock(&rdev->devlist_mtx);
        cfg80211_unlock_rdev(rdev);

        /*
         * Configure power management to the driver here so that its
         * correctly set also after interface type changes etc.
         */
        if ((wdev->iftype == NL80211_IFTYPE_STATION ||
             wdev->iftype == NL80211_IFTYPE_P2P_CLIENT) &&
            rdev->ops->set_power_mgmt)
            if (rdev->ops->set_power_mgmt(wdev->wiphy, dev,
                              wdev->ps,
                              wdev->ps_timeout)) {
                /* assume this means it's off */
                wdev->ps = false;
            }
        break;
    case NETDEV_UNREGISTER:
        /*
         * NB: cannot take rdev->mtx here because this may be
         * called within code protected by it when interfaces
         * are removed with nl80211.
         */
        mutex_lock(&rdev->devlist_mtx);
        /*
         * It is possible to get NETDEV_UNREGISTER
         * multiple times. To detect that, check
         * that the interface is still on the list
         * of registered interfaces, and only then
         * remove and clean it up.
         */
        if (!list_empty(&wdev->list)) {
            sysfs_remove_link(&dev->dev.kobj, "phy80211");
            list_del_rcu(&wdev->list);
            rdev->devlist_generation++;
            cfg80211_mlme_purge_registrations(wdev);
#ifdef CONFIG_CFG80211_WEXT
            kfree(wdev->wext.keys);
#endif
        }
        mutex_unlock(&rdev->devlist_mtx);
        /*
         * synchronise (so that we won't find this netdev
         * from other code any more) and then clear the list
         * head so that the above code can safely check for
         * !list_empty() to avoid double-cleanup.
         */
        synchronize_rcu();
        INIT_LIST_HEAD(&wdev->list);
        /*
         * Ensure that all events have been processed and
         * freed.
         */
        cfg80211_process_wdev_events(wdev);
        break;
    case NETDEV_PRE_UP:
        if (!(wdev->wiphy->interface_modes & BIT(wdev->iftype)))
            return notifier_from_errno(-EOPNOTSUPP);
        if (rfkill_blocked(rdev->rfkill))
            return notifier_from_errno(-ERFKILL);
        mutex_lock(&rdev->devlist_mtx);
        ret = cfg80211_can_add_interface(rdev, wdev->iftype);
        mutex_unlock(&rdev->devlist_mtx);
        if (ret)
            return notifier_from_errno(ret);
        break;
    }

    return NOTIFY_DONE;
}

static struct notifier_block cfg80211_netdev_notifier = {
    .notifier_call = cfg80211_netdev_notifier_call,
};

static void __net_exit cfg80211_pernet_exit(struct net *net)
{
    struct cfg80211_registered_device *rdev;

    rtnl_lock();
    mutex_lock(&cfg80211_mutex);
    list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
        if (net_eq(wiphy_net(&rdev->wiphy), net))
            WARN_ON(cfg80211_switch_netns(rdev, &init_net));
    }
    mutex_unlock(&cfg80211_mutex);
    rtnl_unlock();
}

static struct pernet_operations cfg80211_pernet_ops = {
    .exit = cfg80211_pernet_exit,
};

static int __init cfg80211_init(void)
{
    int err;

    err = register_pernet_device(&cfg80211_pernet_ops);
    if (err)
        goto out_fail_pernet;

    err = wiphy_sysfs_init();
    if (err)
        goto out_fail_sysfs;

    err = register_netdevice_notifier(&cfg80211_netdev_notifier);
    if (err)
        goto out_fail_notifier;

    err = nl80211_init();
    if (err)
        goto out_fail_nl80211;

    ieee80211_debugfs_dir = debugfs_create_dir("ieee80211", NULL);

    err = regulatory_init();
    if (err)
        goto out_fail_reg;

    cfg80211_wq = create_singlethread_workqueue("cfg80211");
    if (!cfg80211_wq)
        goto out_fail_wq;

    return 0;

out_fail_wq:
    regulatory_exit();
out_fail_reg:
    debugfs_remove(ieee80211_debugfs_dir);
out_fail_nl80211:
    unregister_netdevice_notifier(&cfg80211_netdev_notifier);
out_fail_notifier:
    wiphy_sysfs_exit();
out_fail_sysfs:
    unregister_pernet_device(&cfg80211_pernet_ops);
out_fail_pernet:
    return err;
}
subsys_initcall(cfg80211_init);

static void __exit cfg80211_exit(void)
{
    debugfs_remove(ieee80211_debugfs_dir);
    nl80211_exit();
    unregister_netdevice_notifier(&cfg80211_netdev_notifier);
    wiphy_sysfs_exit();
    regulatory_exit();
    unregister_pernet_device(&cfg80211_pernet_ops);
    destroy_workqueue(cfg80211_wq);
}
module_exit(cfg80211_exit);