ARM: OMAP: Fix for possible race condition in omap_free_dma()

[linux-ginger.git] / net / mac80211 / iface.c

/*
 * Interface handling (except master interface)
 *
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright (c) 2006 Jiri Benc <jbenc@suse.cz>
 * Copyright 2008, Johannes Berg <johannes@sipsolutions.net>
 *
 * 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/kernel.h>
#include <linux/if_arp.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "sta_info.h"
#include "debugfs_netdev.h"
#include "mesh.h"
#include "led.h"

/**
 * DOC: Interface list locking
 *
 * The interface list in each struct ieee80211_local is protected
 * three-fold:
 *
 * (1) modifications may only be done under the RTNL
 * (2) modifications and readers are protected against each other by
 *     the iflist_mtx.
 * (3) modifications are done in an RCU manner so atomic readers
 *     can traverse the list in RCU-safe blocks.
 *
 * As a consequence, reads (traversals) of the list can be protected
 * by either the RTNL, the iflist_mtx or RCU.
 */


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;
        }

#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
        printk(KERN_DEBUG "%s: setting MTU %d\n", dev->name, new_mtu);
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
        dev->mtu = new_mtu;
        return 0;
}

static inline int identical_mac_addr_allowed(int type1, int type2)
{
        return type1 == NL80211_IFTYPE_MONITOR ||
                type2 == NL80211_IFTYPE_MONITOR ||
                (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_open(struct net_device *dev)
{
        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
        struct ieee80211_sub_if_data *nsdata;
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta;
        struct ieee80211_if_init_conf conf;
        u32 changed = 0;
        int res;
        u32 hw_reconf_flags = 0;
        u8 null_addr[ETH_ALEN] = {0};

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

        /* we hold the RTNL here so can safely walk the list */
        list_for_each_entry(nsdata, &local->interfaces, list) {
                struct net_device *ndev = nsdata->dev;

                if (ndev != dev && netif_running(ndev)) {
                        /*
                         * 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 (sdata->vif.type == 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 (compare_ether_addr(dev->dev_addr, ndev->dev_addr))
                                continue;

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

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

        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:
                if (!sdata->bss)
                        return -ENOLINK;
                list_add(&sdata->u.vlan.list, &sdata->bss->vlans);
                break;
        case NL80211_IFTYPE_AP:
                sdata->bss = &sdata->u.ap;
                break;
        case NL80211_IFTYPE_MESH_POINT:
                if (!ieee80211_vif_is_mesh(&sdata->vif))
                        break;
                /* mesh ifaces must set allmulti to forward mcast traffic */
                atomic_inc(&local->iff_allmultis);
                break;
        case NL80211_IFTYPE_STATION:
        case NL80211_IFTYPE_MONITOR:
        case NL80211_IFTYPE_ADHOC:
                /* no special treatment */
                break;
        case NL80211_IFTYPE_UNSPECIFIED:
        case __NL80211_IFTYPE_AFTER_LAST:
                /* cannot happen */
                WARN_ON(1);
                break;
        }

        if (local->open_count == 0) {
                res = 0;
                if (local->ops->start)
                        res = local->ops->start(local_to_hw(local));
                if (res)
                        goto err_del_bss;
                /* we're brought up, everything changes */
                hw_reconf_flags = ~0;
                ieee80211_led_radio(local, local->hw.conf.radio_enabled);
        }

        /*
         * Check all interfaces and copy the hopefully now-present
         * MAC address to those that have the special null one.
         */
        list_for_each_entry(nsdata, &local->interfaces, list) {
                struct net_device *ndev = nsdata->dev;

                /*
                 * No need to check netif_running since we do not allow
                 * it to start up with this invalid address.
                 */
                if (compare_ether_addr(null_addr, ndev->dev_addr) == 0)
                        memcpy(ndev->dev_addr,
                               local->hw.wiphy->perm_addr,
                               ETH_ALEN);
        }

        if (compare_ether_addr(null_addr, local->mdev->dev_addr) == 0)
                memcpy(local->mdev->dev_addr, local->hw.wiphy->perm_addr,
                       ETH_ALEN);

        /*
         * Validate the MAC address for this device.
         */
        if (!is_valid_ether_addr(dev->dev_addr)) {
                if (!local->open_count && local->ops->stop)
                        local->ops->stop(local_to_hw(local));
                return -EADDRNOTAVAIL;
        }

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

                /* must be before the call to ieee80211_configure_filter */
                local->monitors++;
                if (local->monitors == 1) {
                        local->hw.conf.flags |= IEEE80211_CONF_RADIOTAP;
                        hw_reconf_flags |= IEEE80211_CONF_CHANGE_RADIOTAP;
                }

                if (sdata->u.mntr_flags & MONITOR_FLAG_FCSFAIL)
                        local->fif_fcsfail++;
                if (sdata->u.mntr_flags & MONITOR_FLAG_PLCPFAIL)
                        local->fif_plcpfail++;
                if (sdata->u.mntr_flags & MONITOR_FLAG_CONTROL)
                        local->fif_control++;
                if (sdata->u.mntr_flags & MONITOR_FLAG_OTHER_BSS)
                        local->fif_other_bss++;

                netif_addr_lock_bh(local->mdev);
                ieee80211_configure_filter(local);
                netif_addr_unlock_bh(local->mdev);
                break;
        case NL80211_IFTYPE_STATION:
        case NL80211_IFTYPE_ADHOC:
                if (sdata->vif.type == NL80211_IFTYPE_STATION)
                        sdata->u.mgd.flags &= ~IEEE80211_STA_PREV_BSSID_SET;
                else
                        sdata->u.ibss.flags &= ~IEEE80211_IBSS_PREV_BSSID_SET;
                /* fall through */
        default:
                conf.vif = &sdata->vif;
                conf.type = sdata->vif.type;
                conf.mac_addr = dev->dev_addr;
                res = local->ops->add_interface(local_to_hw(local), &conf);
                if (res)
                        goto err_stop;

                if (ieee80211_vif_is_mesh(&sdata->vif)) {
                        local->fif_other_bss++;
                        netif_addr_lock_bh(local->mdev);
                        ieee80211_configure_filter(local);
                        netif_addr_unlock_bh(local->mdev);

                        ieee80211_start_mesh(sdata);
                }
                changed |= ieee80211_reset_erp_info(sdata);
                ieee80211_bss_info_change_notify(sdata, changed);
                ieee80211_enable_keys(sdata);

                if (sdata->vif.type == NL80211_IFTYPE_STATION)
                        netif_carrier_off(dev);
                else
                        netif_carrier_on(dev);
        }

        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;
                }

                /* no locking required since STA is not live yet */
                sta->flags |= WLAN_STA_AUTHORIZED;

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

        if (local->open_count == 0) {
                res = dev_open(local->mdev);
                WARN_ON(res);
                if (res)
                        goto err_del_interface;
                tasklet_enable(&local->tx_pending_tasklet);
                tasklet_enable(&local->tasklet);
        }

        /*
         * 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);

        local->open_count++;
        if (hw_reconf_flags) {
                ieee80211_hw_config(local, hw_reconf_flags);
                /*
                 * 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);
        }

        /*
         * ieee80211_sta_work is disabled while network interface
         * is down. Therefore, some configuration changes may not
         * yet be effective. Trigger execution of ieee80211_sta_work
         * to fix this.
         */
        if (sdata->vif.type == NL80211_IFTYPE_STATION)
                queue_work(local->hw.workqueue, &sdata->u.mgd.work);
        else if (sdata->vif.type == NL80211_IFTYPE_ADHOC)
                queue_work(local->hw.workqueue, &sdata->u.ibss.work);

        netif_tx_start_all_queues(dev);

        return 0;
 err_del_interface:
        local->ops->remove_interface(local_to_hw(local), &conf);
 err_stop:
        if (!local->open_count && local->ops->stop)
                local->ops->stop(local_to_hw(local));
 err_del_bss:
        sdata->bss = NULL;
        if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
                list_del(&sdata->u.vlan.list);
        return res;
}

static int ieee80211_stop(struct net_device *dev)
{
        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_if_init_conf conf;
        struct sta_info *sta;
        u32 hw_reconf_flags = 0;

        /*
         * Stop TX on this interface first.
         */
        netif_tx_stop_all_queues(dev);

        /*
         * Now delete all active aggregation sessions.
         */
        rcu_read_lock();

        list_for_each_entry_rcu(sta, &local->sta_list, list) {
                if (sta->sdata == sdata)
                        ieee80211_sta_tear_down_BA_sessions(sta);
        }

        rcu_read_unlock();

        /*
         * Announce that we are leaving the network, in case we are a
         * station interface type. This must be done before removing
         * all stations associated with sta_info_flush, otherwise STA
         * information will be gone and no announce being done.
         */
        if (sdata->vif.type == NL80211_IFTYPE_STATION) {
                if (sdata->u.mgd.state != IEEE80211_STA_MLME_DISABLED)
                        ieee80211_sta_deauthenticate(sdata,
                                WLAN_REASON_DEAUTH_LEAVING);
        }

        /*
         * 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!)
         *
         * We could relax this and only unlink the stations from the
         * hash table and list but keep them on a per-sdata list that
         * will be inserted back again when the interface is brought
         * up again, but I don't currently see a use case for that,
         * except with WDS which gets a STA entry created when it is
         * brought up.
         */
        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);

        dev_mc_unsync(local->mdev, dev);
        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, *tmp;
                struct beacon_data *old_beacon = sdata->u.ap.beacon;

                /* remove beacon */
                rcu_assign_pointer(sdata->u.ap.beacon, NULL);
                synchronize_rcu();
                kfree(old_beacon);

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

        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_RADIOTAP;
                        hw_reconf_flags |= IEEE80211_CONF_CHANGE_RADIOTAP;
                }

                if (sdata->u.mntr_flags & MONITOR_FLAG_FCSFAIL)
                        local->fif_fcsfail--;
                if (sdata->u.mntr_flags & MONITOR_FLAG_PLCPFAIL)
                        local->fif_plcpfail--;
                if (sdata->u.mntr_flags & MONITOR_FLAG_CONTROL)
                        local->fif_control--;
                if (sdata->u.mntr_flags & MONITOR_FLAG_OTHER_BSS)
                        local->fif_other_bss--;

                netif_addr_lock_bh(local->mdev);
                ieee80211_configure_filter(local);
                netif_addr_unlock_bh(local->mdev);
                break;
        case NL80211_IFTYPE_STATION:
                memset(sdata->u.mgd.bssid, 0, ETH_ALEN);
                del_timer_sync(&sdata->u.mgd.chswitch_timer);
                del_timer_sync(&sdata->u.mgd.timer);
                /*
                 * If the timer fired while we waited for it, it will have
                 * requeued the work. Now the work will be running again
                 * but will not rearm the timer again because it checks
                 * whether the interface is running, which, at this point,
                 * it no longer is.
                 */
                cancel_work_sync(&sdata->u.mgd.work);
                cancel_work_sync(&sdata->u.mgd.chswitch_work);

                cancel_work_sync(&sdata->u.mgd.beacon_loss_work);

                /*
                 * When we get here, the interface is marked down.
                 * Call synchronize_rcu() to wait for the RX path
                 * should it be using the interface and enqueuing
                 * frames at this very time on another CPU.
                 */
                synchronize_rcu();
                skb_queue_purge(&sdata->u.mgd.skb_queue);

                sdata->u.mgd.flags &= ~(IEEE80211_STA_PRIVACY_INVOKED |
                                        IEEE80211_STA_TKIP_WEP_USED);
                kfree(sdata->u.mgd.extra_ie);
                sdata->u.mgd.extra_ie = NULL;
                sdata->u.mgd.extra_ie_len = 0;
                /* fall through */
        case NL80211_IFTYPE_ADHOC:
                if (sdata->vif.type == NL80211_IFTYPE_ADHOC) {
                        memset(sdata->u.ibss.bssid, 0, ETH_ALEN);
                        del_timer_sync(&sdata->u.ibss.timer);
                        cancel_work_sync(&sdata->u.ibss.work);
                        synchronize_rcu();
                        skb_queue_purge(&sdata->u.ibss.skb_queue);
                }
                /* fall through */
        case NL80211_IFTYPE_MESH_POINT:
                if (ieee80211_vif_is_mesh(&sdata->vif)) {
                        /* other_bss and allmulti are always set on mesh
                         * ifaces */
                        local->fif_other_bss--;
                        atomic_dec(&local->iff_allmultis);

                        netif_addr_lock_bh(local->mdev);
                        ieee80211_configure_filter(local);
                        netif_addr_unlock_bh(local->mdev);

                        ieee80211_stop_mesh(sdata);
                }
                /* fall through */
        default:
                if (local->scan_sdata == sdata) {
                        if (!local->ops->hw_scan)
                                cancel_delayed_work_sync(&local->scan_work);
                        /*
                         * The software scan can no longer run now, so we can
                         * clear out the scan_sdata reference. However, the
                         * hardware scan may still be running. The complete
                         * function must be prepared to handle a NULL value.
                         */
                        local->scan_sdata = NULL;
                        /*
                         * The memory barrier guarantees that another CPU
                         * that is hardware-scanning will now see the fact
                         * that this interface is gone.
                         */
                        smp_mb();
                        /*
                         * If software scanning, complete the scan but since
                         * the scan_sdata is NULL already don't send out a
                         * scan event to userspace -- the scan is incomplete.
                         */
                        if (local->sw_scanning)
                                ieee80211_scan_completed(&local->hw, true);
                }

                conf.vif = &sdata->vif;
                conf.type = sdata->vif.type;
                conf.mac_addr = dev->dev_addr;
                /* disable all keys for as long as this netdev is down */
                ieee80211_disable_keys(sdata);
                local->ops->remove_interface(local_to_hw(local), &conf);
        }

        sdata->bss = NULL;

        if (local->open_count == 0) {
                if (netif_running(local->mdev))
                        dev_close(local->mdev);

                if (local->ops->stop)
                        local->ops->stop(local_to_hw(local));

                ieee80211_led_radio(local, 0);

                flush_workqueue(local->hw.workqueue);

                tasklet_disable(&local->tx_pending_tasklet);
                tasklet_disable(&local->tasklet);

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

        /* do after stop to avoid reconfiguring when we stop anyway */
        if (hw_reconf_flags)
                ieee80211_hw_config(local, hw_reconf_flags);

        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;
        }

        dev_mc_sync(local->mdev, dev);
}

/*
 * Called when the netdev is removed or, by the code below, before
 * the interface type changes.
 */
static void ieee80211_teardown_sdata(struct net_device *dev)
{
        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
        struct ieee80211_local *local = sdata->local;
        struct beacon_data *beacon;
        struct sk_buff *skb;
        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;

        switch (sdata->vif.type) {
        case NL80211_IFTYPE_AP:
                beacon = sdata->u.ap.beacon;
                rcu_assign_pointer(sdata->u.ap.beacon, NULL);
                synchronize_rcu();
                kfree(beacon);

                while ((skb = skb_dequeue(&sdata->u.ap.ps_bc_buf))) {
                        local->total_ps_buffered--;
                        dev_kfree_skb(skb);
                }

                break;
        case NL80211_IFTYPE_MESH_POINT:
                if (ieee80211_vif_is_mesh(&sdata->vif))
                        mesh_rmc_free(sdata);
                break;
        case NL80211_IFTYPE_ADHOC:
                kfree_skb(sdata->u.ibss.probe_resp);
                break;
        case NL80211_IFTYPE_STATION:
                kfree(sdata->u.mgd.extra_ie);
                kfree(sdata->u.mgd.assocreq_ies);
                kfree(sdata->u.mgd.assocresp_ies);
                kfree(sdata->u.mgd.sme_auth_ie);
                break;
        case NL80211_IFTYPE_WDS:
        case NL80211_IFTYPE_AP_VLAN:
        case NL80211_IFTYPE_MONITOR:
                break;
        case NL80211_IFTYPE_UNSPECIFIED:
        case __NL80211_IFTYPE_AFTER_LAST:
                BUG();
                break;
        }

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

static const struct net_device_ops ieee80211_dataif_ops = {
        .ndo_open               = ieee80211_open,
        .ndo_stop               = ieee80211_stop,
        .ndo_uninit             = ieee80211_teardown_sdata,
        .ndo_start_xmit         = ieee80211_subif_start_xmit,
        .ndo_set_multicast_list = ieee80211_set_multicast_list,
        .ndo_change_mtu         = ieee80211_change_mtu,
        .ndo_set_mac_address    = eth_mac_addr,
};

static const struct net_device_ops ieee80211_monitorif_ops = {
        .ndo_open               = ieee80211_open,
        .ndo_stop               = ieee80211_stop,
        .ndo_uninit             = ieee80211_teardown_sdata,
        .ndo_start_xmit         = ieee80211_monitor_start_xmit,
        .ndo_set_multicast_list = ieee80211_set_multicast_list,
        .ndo_change_mtu         = ieee80211_change_mtu,
        .ndo_set_mac_address    = eth_mac_addr,
};

static void ieee80211_if_setup(struct net_device *dev)
{
        ether_setup(dev);
        dev->netdev_ops = &ieee80211_dataif_ops;
        dev->wireless_handlers = &ieee80211_iw_handler_def;
        dev->destructor = free_netdev;
}

/*
 * 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->dev->netdev_ops = &ieee80211_dataif_ops;
        sdata->wdev.iftype = type;

        /* only monitor differs */
        sdata->dev->type = ARPHRD_ETHER;

        switch (type) {
        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_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:
                break;
        case NL80211_IFTYPE_UNSPECIFIED:
        case __NL80211_IFTYPE_AFTER_LAST:
                BUG();
                break;
        }

        ieee80211_debugfs_add_netdev(sdata);
}

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

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

        /*
         * We could, here, on changes between IBSS/STA/MESH modes,
         * invoke an MLME function instead that disassociates etc.
         * and goes into the requested mode.
         */

        if (netif_running(sdata->dev))
                return -EBUSY;

        /* Purge and reset type-dependent state. */
        ieee80211_teardown_sdata(sdata->dev);
        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->hw.conf.channel->band);
        sdata->drop_unencrypted = 0;

        return 0;
}

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

        ASSERT_RTNL();

        ndev = alloc_netdev(sizeof(*sdata) + local->hw.vif_data_size,
                            name, ieee80211_if_setup);
        if (!ndev)
                return -ENOMEM;

        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)
                goto fail;

        memcpy(ndev->dev_addr, local->hw.wiphy->perm_addr, ETH_ALEN);
        SET_NETDEV_DEV(ndev, wiphy_dev(local->hw.wiphy));
        ndev->features |= NETIF_F_NETNS_LOCAL;

        /* don't use IEEE80211_DEV_TO_SUB_IF because it checks too much */
        sdata = netdev_priv(ndev);
        ndev->ieee80211_ptr = &sdata->wdev;

        /* initialise type-independent data */
        sdata->wdev.wiphy = local->hw.wiphy;
        sdata->local = local;
        sdata->dev = ndev;

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

        INIT_LIST_HEAD(&sdata->key_list);

        sdata->force_unicast_rateidx = -1;
        sdata->max_ratectrl_rateidx = -1;

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

        ret = register_netdevice(ndev);
        if (ret)
                goto fail;

        if (ieee80211_vif_is_mesh(&sdata->vif) &&
            params && params->mesh_id_len)
                ieee80211_sdata_set_mesh_id(sdata,
                                            params->mesh_id_len,
                                            params->mesh_id);

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

        if (new_dev)
                *new_dev = ndev;

        return 0;

 fail:
        free_netdev(ndev);
        return ret;
}

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();
        unregister_netdevice(sdata->dev);
}

/*
 * 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;

        ASSERT_RTNL();

        list_for_each_entry_safe(sdata, tmp, &local->interfaces, list) {
                /*
                 * we cannot hold the iflist_mtx across unregister_netdevice,
                 * but we only need to hold it for list modifications to lock
                 * out readers since we're under the RTNL here as all other
                 * writers.
                 */
                mutex_lock(&local->iflist_mtx);
                list_del(&sdata->list);
                mutex_unlock(&local->iflist_mtx);

                unregister_netdevice(sdata->dev);
        }
}