sta_info.c

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/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2006-2007  Jiri Benc <[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/module.h>
#include <linux/init.h>
#include <linux/etherdevice.h>
#include <linux/netdevice.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/timer.h>
#include <linux/rtnetlink.h>

#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "driver-ops.h"
#include "rate.h"
#include "sta_info.h"
#include "debugfs_sta.h"
#include "mesh.h"
#include "wme.h"

/* Caller must hold local->sta_mtx */
static int sta_info_hash_del(struct ieee80211_local *local,
                 struct sta_info *sta)
{
    struct sta_info *s;

    s = rcu_dereference_protected(local->sta_hash[STA_HASH(sta->sta.addr)],
                      lockdep_is_held(&local->sta_mtx));
    if (!s)
        return -ENOENT;
    if (s == sta) {
        rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)],
                   s->hnext);
        return 0;
    }

    while (rcu_access_pointer(s->hnext) &&
           rcu_access_pointer(s->hnext) != sta)
        s = rcu_dereference_protected(s->hnext,
                    lockdep_is_held(&local->sta_mtx));
    if (rcu_access_pointer(s->hnext)) {
        rcu_assign_pointer(s->hnext, sta->hnext);
        return 0;
    }

    return -ENOENT;
}

static void free_sta_work(struct work_struct *wk)
{
    struct sta_info *sta = container_of(wk, struct sta_info, free_sta_wk);
    int ac, i;
    struct tid_ampdu_tx *tid_tx;
    struct ieee80211_sub_if_data *sdata = sta->sdata;
    struct ieee80211_local *local = sdata->local;

    /*
     * At this point, when being called as call_rcu callback,
     * neither mac80211 nor the driver can reference this
     * sta struct any more except by still existing timers
     * associated with this station that we clean up below.
     */

    if (test_sta_flag(sta, WLAN_STA_PS_STA)) {
        BUG_ON(!sdata->bss);

        clear_sta_flag(sta, WLAN_STA_PS_STA);

        atomic_dec(&sdata->bss->num_sta_ps);
        sta_info_recalc_tim(sta);
    }

    for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
        local->total_ps_buffered -= skb_queue_len(&sta->ps_tx_buf[ac]);
        ieee80211_purge_tx_queue(&local->hw, &sta->ps_tx_buf[ac]);
        ieee80211_purge_tx_queue(&local->hw, &sta->tx_filtered[ac]);
    }

#ifdef CONFIG_MAC80211_MESH
    if (ieee80211_vif_is_mesh(&sdata->vif)) {
        mesh_accept_plinks_update(sdata);
        mesh_plink_deactivate(sta);
        del_timer_sync(&sta->plink_timer);
    }
#endif

    cancel_work_sync(&sta->drv_unblock_wk);

    /*
     * Destroy aggregation state here. It would be nice to wait for the
     * driver to finish aggregation stop and then clean up, but for now
     * drivers have to handle aggregation stop being requested, followed
     * directly by station destruction.
     */
    for (i = 0; i < STA_TID_NUM; i++) {
        tid_tx = rcu_dereference_raw(sta->ampdu_mlme.tid_tx[i]);
        if (!tid_tx)
            continue;
        ieee80211_purge_tx_queue(&local->hw, &tid_tx->pending);
        kfree(tid_tx);
    }

    sta_info_free(local, sta);
}

static void free_sta_rcu(struct rcu_head *h)
{
    struct sta_info *sta = container_of(h, struct sta_info, rcu_head);

    ieee80211_queue_work(&sta->local->hw, &sta->free_sta_wk);
}

/* protected by RCU */
struct sta_info *sta_info_get(struct ieee80211_sub_if_data *sdata,
                  const u8 *addr)
{
    struct ieee80211_local *local = sdata->local;
    struct sta_info *sta;

    sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
                    lockdep_is_held(&local->sta_mtx));
    while (sta) {
        if (sta->sdata == sdata &&
            ether_addr_equal(sta->sta.addr, addr))
            break;
        sta = rcu_dereference_check(sta->hnext,
                        lockdep_is_held(&local->sta_mtx));
    }
    return sta;
}

/*
 * Get sta info either from the specified interface
 * or from one of its vlans
 */
struct sta_info *sta_info_get_bss(struct ieee80211_sub_if_data *sdata,
                  const u8 *addr)
{
    struct ieee80211_local *local = sdata->local;
    struct sta_info *sta;

    sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
                    lockdep_is_held(&local->sta_mtx));
    while (sta) {
        if ((sta->sdata == sdata ||
             (sta->sdata->bss && sta->sdata->bss == sdata->bss)) &&
            ether_addr_equal(sta->sta.addr, addr))
            break;
        sta = rcu_dereference_check(sta->hnext,
                        lockdep_is_held(&local->sta_mtx));
    }
    return sta;
}

struct sta_info *sta_info_get_by_idx(struct ieee80211_sub_if_data *sdata,
                     int idx)
{
    struct ieee80211_local *local = sdata->local;
    struct sta_info *sta;
    int i = 0;

    list_for_each_entry_rcu(sta, &local->sta_list, list) {
        if (sdata != sta->sdata)
            continue;
        if (i < idx) {
            ++i;
            continue;
        }
        return sta;
    }

    return NULL;
}

void sta_info_free(struct ieee80211_local *local, struct sta_info *sta)
{
    if (sta->rate_ctrl)
        rate_control_free_sta(sta);

    sta_dbg(sta->sdata, "Destroyed STA %pM\n", sta->sta.addr);

    kfree(sta);
}

/* Caller must hold local->sta_mtx */
static void sta_info_hash_add(struct ieee80211_local *local,
                  struct sta_info *sta)
{
    lockdep_assert_held(&local->sta_mtx);
    sta->hnext = local->sta_hash[STA_HASH(sta->sta.addr)];
    rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)], sta);
}

static void sta_unblock(struct work_struct *wk)
{
    struct sta_info *sta;

    sta = container_of(wk, struct sta_info, drv_unblock_wk);

    if (sta->dead)
        return;

    if (!test_sta_flag(sta, WLAN_STA_PS_STA)) {
        local_bh_disable();
        ieee80211_sta_ps_deliver_wakeup(sta);
        local_bh_enable();
    } else if (test_and_clear_sta_flag(sta, WLAN_STA_PSPOLL)) {
        clear_sta_flag(sta, WLAN_STA_PS_DRIVER);

        local_bh_disable();
        ieee80211_sta_ps_deliver_poll_response(sta);
        local_bh_enable();
    } else if (test_and_clear_sta_flag(sta, WLAN_STA_UAPSD)) {
        clear_sta_flag(sta, WLAN_STA_PS_DRIVER);

        local_bh_disable();
        ieee80211_sta_ps_deliver_uapsd(sta);
        local_bh_enable();
    } else
        clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
}

static int sta_prepare_rate_control(struct ieee80211_local *local,
                    struct sta_info *sta, gfp_t gfp)
{
    if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
        return 0;

    sta->rate_ctrl = local->rate_ctrl;
    sta->rate_ctrl_priv = rate_control_alloc_sta(sta->rate_ctrl,
                             &sta->sta, gfp);
    if (!sta->rate_ctrl_priv)
        return -ENOMEM;

    return 0;
}

struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
                const u8 *addr, gfp_t gfp)
{
    struct ieee80211_local *local = sdata->local;
    struct sta_info *sta;
    struct timespec uptime;
    int i;

    sta = kzalloc(sizeof(*sta) + local->hw.sta_data_size, gfp);
    if (!sta)
        return NULL;

    spin_lock_init(&sta->lock);
    INIT_WORK(&sta->drv_unblock_wk, sta_unblock);
    INIT_WORK(&sta->free_sta_wk, free_sta_work);
    INIT_WORK(&sta->ampdu_mlme.work, ieee80211_ba_session_work);
    mutex_init(&sta->ampdu_mlme.mtx);

    memcpy(sta->sta.addr, addr, ETH_ALEN);
    sta->local = local;
    sta->sdata = sdata;
    sta->last_rx = jiffies;

    sta->sta_state = IEEE80211_STA_NONE;

    do_posix_clock_monotonic_gettime(&uptime);
    sta->last_connected = uptime.tv_sec;
    ewma_init(&sta->avg_signal, 1024, 8);

    if (sta_prepare_rate_control(local, sta, gfp)) {
        kfree(sta);
        return NULL;
    }

    for (i = 0; i < STA_TID_NUM; i++) {
        /*
         * timer_to_tid must be initialized with identity mapping
         * to enable session_timer's data differentiation. See
         * sta_rx_agg_session_timer_expired for usage.
         */
        sta->timer_to_tid[i] = i;
    }
    for (i = 0; i < IEEE80211_NUM_ACS; i++) {
        skb_queue_head_init(&sta->ps_tx_buf[i]);
        skb_queue_head_init(&sta->tx_filtered[i]);
    }

    for (i = 0; i < NUM_RX_DATA_QUEUES; i++)
        sta->last_seq_ctrl[i] = cpu_to_le16(USHRT_MAX);

    sta_dbg(sdata, "Allocated STA %pM\n", sta->sta.addr);

#ifdef CONFIG_MAC80211_MESH
    sta->plink_state = NL80211_PLINK_LISTEN;
    init_timer(&sta->plink_timer);
#endif

    return sta;
}

static int sta_info_insert_check(struct sta_info *sta)
{
    struct ieee80211_sub_if_data *sdata = sta->sdata;

    /*
     * Can't be a WARN_ON because it can be triggered through a race:
     * something inserts a STA (on one CPU) without holding the RTNL
     * and another CPU turns off the net device.
     */
    if (unlikely(!ieee80211_sdata_running(sdata)))
        return -ENETDOWN;

    if (WARN_ON(ether_addr_equal(sta->sta.addr, sdata->vif.addr) ||
            is_multicast_ether_addr(sta->sta.addr)))
        return -EINVAL;

    return 0;
}

static int sta_info_insert_drv_state(struct ieee80211_local *local,
                     struct ieee80211_sub_if_data *sdata,
                     struct sta_info *sta)
{
    enum ieee80211_sta_state state;
    int err = 0;

    for (state = IEEE80211_STA_NOTEXIST; state < sta->sta_state; state++) {
        err = drv_sta_state(local, sdata, sta, state, state + 1);
        if (err)
            break;
    }

    if (!err) {
        /*
         * Drivers using legacy sta_add/sta_remove callbacks only
         * get uploaded set to true after sta_add is called.
         */
        if (!local->ops->sta_add)
            sta->uploaded = true;
        return 0;
    }

    if (sdata->vif.type == NL80211_IFTYPE_ADHOC) {
        sdata_info(sdata,
               "failed to move IBSS STA %pM to state %d (%d) - keeping it anyway\n",
               sta->sta.addr, state + 1, err);
        err = 0;
    }

    /* unwind on error */
    for (; state > IEEE80211_STA_NOTEXIST; state--)
        WARN_ON(drv_sta_state(local, sdata, sta, state, state - 1));

    return err;
}

/*
 * should be called with sta_mtx locked
 * this function replaces the mutex lock
 * with a RCU lock
 */
static int sta_info_insert_finish(struct sta_info *sta) __acquires(RCU)
{
    struct ieee80211_local *local = sta->local;
    struct ieee80211_sub_if_data *sdata = sta->sdata;
    struct station_info sinfo;
    int err = 0;

    lockdep_assert_held(&local->sta_mtx);

    /* check if STA exists already */
    if (sta_info_get_bss(sdata, sta->sta.addr)) {
        err = -EEXIST;
        goto out_err;
    }

    /* notify driver */
    err = sta_info_insert_drv_state(local, sdata, sta);
    if (err)
        goto out_err;

    local->num_sta++;
    local->sta_generation++;
    smp_mb();

    /* make the station visible */
    sta_info_hash_add(local, sta);

    list_add_rcu(&sta->list, &local->sta_list);

    set_sta_flag(sta, WLAN_STA_INSERTED);

    ieee80211_sta_debugfs_add(sta);
    rate_control_add_sta_debugfs(sta);

    memset(&sinfo, 0, sizeof(sinfo));
    sinfo.filled = 0;
    sinfo.generation = local->sta_generation;
    cfg80211_new_sta(sdata->dev, sta->sta.addr, &sinfo, GFP_KERNEL);

    sta_dbg(sdata, "Inserted STA %pM\n", sta->sta.addr);

    /* move reference to rcu-protected */
    rcu_read_lock();
    mutex_unlock(&local->sta_mtx);

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

    return 0;
 out_err:
    mutex_unlock(&local->sta_mtx);
    rcu_read_lock();
    return err;
}

int sta_info_insert_rcu(struct sta_info *sta) __acquires(RCU)
{
    struct ieee80211_local *local = sta->local;
    int err = 0;

    might_sleep();

    err = sta_info_insert_check(sta);
    if (err) {
        rcu_read_lock();
        goto out_free;
    }

    mutex_lock(&local->sta_mtx);

    err = sta_info_insert_finish(sta);
    if (err)
        goto out_free;

    return 0;
 out_free:
    BUG_ON(!err);
    sta_info_free(local, sta);
    return err;
}

int sta_info_insert(struct sta_info *sta)
{
    int err = sta_info_insert_rcu(sta);

    rcu_read_unlock();

    return err;
}

static inline void __bss_tim_set(struct ieee80211_if_ap *bss, u16 aid)
{
    /*
     * This format has been mandated by the IEEE specifications,
     * so this line may not be changed to use the __set_bit() format.
     */
    bss->tim[aid / 8] |= (1 << (aid % 8));
}

static inline void __bss_tim_clear(struct ieee80211_if_ap *bss, u16 aid)
{
    /*
     * This format has been mandated by the IEEE specifications,
     * so this line may not be changed to use the __clear_bit() format.
     */
    bss->tim[aid / 8] &= ~(1 << (aid % 8));
}

static unsigned long ieee80211_tids_for_ac(int ac)
{
    /* If we ever support TIDs > 7, this obviously needs to be adjusted */
    switch (ac) {
    case IEEE80211_AC_VO:
        return BIT(6) | BIT(7);
    case IEEE80211_AC_VI:
        return BIT(4) | BIT(5);
    case IEEE80211_AC_BE:
        return BIT(0) | BIT(3);
    case IEEE80211_AC_BK:
        return BIT(1) | BIT(2);
    default:
        WARN_ON(1);
        return 0;
    }
}

void sta_info_recalc_tim(struct sta_info *sta)
{
    struct ieee80211_local *local = sta->local;
    struct ieee80211_if_ap *bss = sta->sdata->bss;
    unsigned long flags;
    bool indicate_tim = false;
    u8 ignore_for_tim = sta->sta.uapsd_queues;
    int ac;

    if (WARN_ON_ONCE(!sta->sdata->bss))
        return;

    /* No need to do anything if the driver does all */
    if (local->hw.flags & IEEE80211_HW_AP_LINK_PS)
        return;

    if (sta->dead)
        goto done;

    /*
     * If all ACs are delivery-enabled then we should build
     * the TIM bit for all ACs anyway; if only some are then
     * we ignore those and build the TIM bit using only the
     * non-enabled ones.
     */
    if (ignore_for_tim == BIT(IEEE80211_NUM_ACS) - 1)
        ignore_for_tim = 0;

    for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
        unsigned long tids;

        if (ignore_for_tim & BIT(ac))
            continue;

        indicate_tim |= !skb_queue_empty(&sta->tx_filtered[ac]) ||
                !skb_queue_empty(&sta->ps_tx_buf[ac]);
        if (indicate_tim)
            break;

        tids = ieee80211_tids_for_ac(ac);

        indicate_tim |=
            sta->driver_buffered_tids & tids;
    }

 done:
    spin_lock_irqsave(&local->tim_lock, flags);

    if (indicate_tim)
        __bss_tim_set(bss, sta->sta.aid);
    else
        __bss_tim_clear(bss, sta->sta.aid);

    if (local->ops->set_tim) {
        local->tim_in_locked_section = true;
        drv_set_tim(local, &sta->sta, indicate_tim);
        local->tim_in_locked_section = false;
    }

    spin_unlock_irqrestore(&local->tim_lock, flags);
}

static bool sta_info_buffer_expired(struct sta_info *sta, struct sk_buff *skb)
{
    struct ieee80211_tx_info *info;
    int timeout;

    if (!skb)
        return false;

    info = IEEE80211_SKB_CB(skb);

    /* Timeout: (2 * listen_interval * beacon_int * 1024 / 1000000) sec */
    timeout = (sta->listen_interval *
           sta->sdata->vif.bss_conf.beacon_int *
           32 / 15625) * HZ;
    if (timeout < STA_TX_BUFFER_EXPIRE)
        timeout = STA_TX_BUFFER_EXPIRE;
    return time_after(jiffies, info->control.jiffies + timeout);
}


static bool sta_info_cleanup_expire_buffered_ac(struct ieee80211_local *local,
                        struct sta_info *sta, int ac)
{
    unsigned long flags;
    struct sk_buff *skb;

    /*
     * First check for frames that should expire on the filtered
     * queue. Frames here were rejected by the driver and are on
     * a separate queue to avoid reordering with normal PS-buffered
     * frames. They also aren't accounted for right now in the
     * total_ps_buffered counter.
     */
    for (;;) {
        spin_lock_irqsave(&sta->tx_filtered[ac].lock, flags);
        skb = skb_peek(&sta->tx_filtered[ac]);
        if (sta_info_buffer_expired(sta, skb))
            skb = __skb_dequeue(&sta->tx_filtered[ac]);
        else
            skb = NULL;
        spin_unlock_irqrestore(&sta->tx_filtered[ac].lock, flags);

        /*
         * Frames are queued in order, so if this one
         * hasn't expired yet we can stop testing. If
         * we actually reached the end of the queue we
         * also need to stop, of course.
         */
        if (!skb)
            break;
        ieee80211_free_txskb(&local->hw, skb);
    }

    /*
     * Now also check the normal PS-buffered queue, this will
     * only find something if the filtered queue was emptied
     * since the filtered frames are all before the normal PS
     * buffered frames.
     */
    for (;;) {
        spin_lock_irqsave(&sta->ps_tx_buf[ac].lock, flags);
        skb = skb_peek(&sta->ps_tx_buf[ac]);
        if (sta_info_buffer_expired(sta, skb))
            skb = __skb_dequeue(&sta->ps_tx_buf[ac]);
        else
            skb = NULL;
        spin_unlock_irqrestore(&sta->ps_tx_buf[ac].lock, flags);

        /*
         * frames are queued in order, so if this one
         * hasn't expired yet (or we reached the end of
         * the queue) we can stop testing
         */
        if (!skb)
            break;

        local->total_ps_buffered--;
        ps_dbg(sta->sdata, "Buffered frame expired (STA %pM)\n",
               sta->sta.addr);
        ieee80211_free_txskb(&local->hw, skb);
    }

    /*
     * Finally, recalculate the TIM bit for this station -- it might
     * now be clear because the station was too slow to retrieve its
     * frames.
     */
    sta_info_recalc_tim(sta);

    /*
     * Return whether there are any frames still buffered, this is
     * used to check whether the cleanup timer still needs to run,
     * if there are no frames we don't need to rearm the timer.
     */
    return !(skb_queue_empty(&sta->ps_tx_buf[ac]) &&
         skb_queue_empty(&sta->tx_filtered[ac]));
}

static bool sta_info_cleanup_expire_buffered(struct ieee80211_local *local,
                         struct sta_info *sta)
{
    bool have_buffered = false;
    int ac;

    /* This is only necessary for stations on BSS interfaces */
    if (!sta->sdata->bss)
        return false;

    for (ac = 0; ac < IEEE80211_NUM_ACS; ac++)
        have_buffered |=
            sta_info_cleanup_expire_buffered_ac(local, sta, ac);

    return have_buffered;
}

int __must_check __sta_info_destroy(struct sta_info *sta)
{
    struct ieee80211_local *local;
    struct ieee80211_sub_if_data *sdata;
    int ret, i;

    might_sleep();

    if (!sta)
        return -ENOENT;

    local = sta->local;
    sdata = sta->sdata;

    lockdep_assert_held(&local->sta_mtx);

    /*
     * Before removing the station from the driver and
     * rate control, it might still start new aggregation
     * sessions -- block that to make sure the tear-down
     * will be sufficient.
     */
    set_sta_flag(sta, WLAN_STA_BLOCK_BA);
    ieee80211_sta_tear_down_BA_sessions(sta, false);

    ret = sta_info_hash_del(local, sta);
    if (ret)
        return ret;

    list_del_rcu(&sta->list);

    mutex_lock(&local->key_mtx);
    for (i = 0; i < NUM_DEFAULT_KEYS; i++)
        __ieee80211_key_free(key_mtx_dereference(local, sta->gtk[i]));
    if (sta->ptk)
        __ieee80211_key_free(key_mtx_dereference(local, sta->ptk));
    mutex_unlock(&local->key_mtx);

    sta->dead = true;

    local->num_sta--;
    local->sta_generation++;

    if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
        RCU_INIT_POINTER(sdata->u.vlan.sta, NULL);

    while (sta->sta_state > IEEE80211_STA_NONE) {
        ret = sta_info_move_state(sta, sta->sta_state - 1);
        if (ret) {
            WARN_ON_ONCE(1);
            break;
        }
    }

    if (sta->uploaded) {
        ret = drv_sta_state(local, sdata, sta, IEEE80211_STA_NONE,
                    IEEE80211_STA_NOTEXIST);
        WARN_ON_ONCE(ret != 0);
    }

    sta_dbg(sdata, "Removed STA %pM\n", sta->sta.addr);

    cfg80211_del_sta(sdata->dev, sta->sta.addr, GFP_KERNEL);

    rate_control_remove_sta_debugfs(sta);
    ieee80211_sta_debugfs_remove(sta);

    call_rcu(&sta->rcu_head, free_sta_rcu);

    return 0;
}

int sta_info_destroy_addr(struct ieee80211_sub_if_data *sdata, const u8 *addr)
{
    struct sta_info *sta;
    int ret;

    mutex_lock(&sdata->local->sta_mtx);
    sta = sta_info_get(sdata, addr);
    ret = __sta_info_destroy(sta);
    mutex_unlock(&sdata->local->sta_mtx);

    return ret;
}

int sta_info_destroy_addr_bss(struct ieee80211_sub_if_data *sdata,
                  const u8 *addr)
{
    struct sta_info *sta;
    int ret;

    mutex_lock(&sdata->local->sta_mtx);
    sta = sta_info_get_bss(sdata, addr);
    ret = __sta_info_destroy(sta);
    mutex_unlock(&sdata->local->sta_mtx);

    return ret;
}

static void sta_info_cleanup(unsigned long data)
{
    struct ieee80211_local *local = (struct ieee80211_local *) data;
    struct sta_info *sta;
    bool timer_needed = false;

    rcu_read_lock();
    list_for_each_entry_rcu(sta, &local->sta_list, list)
        if (sta_info_cleanup_expire_buffered(local, sta))
            timer_needed = true;
    rcu_read_unlock();

    if (local->quiescing)
        return;

    if (!timer_needed)
        return;

    mod_timer(&local->sta_cleanup,
          round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL));
}

void sta_info_init(struct ieee80211_local *local)
{
    spin_lock_init(&local->tim_lock);
    mutex_init(&local->sta_mtx);
    INIT_LIST_HEAD(&local->sta_list);

    setup_timer(&local->sta_cleanup, sta_info_cleanup,
            (unsigned long)local);
}

void sta_info_stop(struct ieee80211_local *local)
{
    del_timer(&local->sta_cleanup);
    sta_info_flush(local, NULL);
}

int sta_info_flush(struct ieee80211_local *local,
           struct ieee80211_sub_if_data *sdata)
{
    struct sta_info *sta, *tmp;
    int ret = 0;

    might_sleep();

    mutex_lock(&local->sta_mtx);
    list_for_each_entry_safe(sta, tmp, &local->sta_list, list) {
        if (!sdata || sdata == sta->sdata) {
            WARN_ON(__sta_info_destroy(sta));
            ret++;
        }
    }
    mutex_unlock(&local->sta_mtx);

    return ret;
}

void ieee80211_sta_expire(struct ieee80211_sub_if_data *sdata,
              unsigned long exp_time)
{
    struct ieee80211_local *local = sdata->local;
    struct sta_info *sta, *tmp;

    mutex_lock(&local->sta_mtx);

    list_for_each_entry_safe(sta, tmp, &local->sta_list, list) {
        if (sdata != sta->sdata)
            continue;

        if (time_after(jiffies, sta->last_rx + exp_time)) {
            ibss_dbg(sdata, "expiring inactive STA %pM\n",
                 sta->sta.addr);
            WARN_ON(__sta_info_destroy(sta));
        }
    }

    mutex_unlock(&local->sta_mtx);
}

struct ieee80211_sta *ieee80211_find_sta_by_ifaddr(struct ieee80211_hw *hw,
                           const u8 *addr,
                           const u8 *localaddr)
{
    struct sta_info *sta, *nxt;

    /*
     * Just return a random station if localaddr is NULL
     * ... first in list.
     */
    for_each_sta_info(hw_to_local(hw), addr, sta, nxt) {
        if (localaddr &&
            !ether_addr_equal(sta->sdata->vif.addr, localaddr))
            continue;
        if (!sta->uploaded)
            return NULL;
        return &sta->sta;
    }

    return NULL;
}
EXPORT_SYMBOL_GPL(ieee80211_find_sta_by_ifaddr);

struct ieee80211_sta *ieee80211_find_sta(struct ieee80211_vif *vif,
                     const u8 *addr)
{
    struct sta_info *sta;

    if (!vif)
        return NULL;

    sta = sta_info_get_bss(vif_to_sdata(vif), addr);
    if (!sta)
        return NULL;

    if (!sta->uploaded)
        return NULL;

    return &sta->sta;
}
EXPORT_SYMBOL(ieee80211_find_sta);

static void clear_sta_ps_flags(void *_sta)
{
    struct sta_info *sta = _sta;
    struct ieee80211_sub_if_data *sdata = sta->sdata;

    clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
    if (test_and_clear_sta_flag(sta, WLAN_STA_PS_STA))
        atomic_dec(&sdata->bss->num_sta_ps);
}

/* powersave support code */
void ieee80211_sta_ps_deliver_wakeup(struct sta_info *sta)
{
    struct ieee80211_sub_if_data *sdata = sta->sdata;
    struct ieee80211_local *local = sdata->local;
    struct sk_buff_head pending;
    int filtered = 0, buffered = 0, ac;
    unsigned long flags;

    clear_sta_flag(sta, WLAN_STA_SP);

    BUILD_BUG_ON(BITS_TO_LONGS(STA_TID_NUM) > 1);
    sta->driver_buffered_tids = 0;

    if (!(local->hw.flags & IEEE80211_HW_AP_LINK_PS))
        drv_sta_notify(local, sdata, STA_NOTIFY_AWAKE, &sta->sta);

    skb_queue_head_init(&pending);

    /* Send all buffered frames to the station */
    for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
        int count = skb_queue_len(&pending), tmp;

        spin_lock_irqsave(&sta->tx_filtered[ac].lock, flags);
        skb_queue_splice_tail_init(&sta->tx_filtered[ac], &pending);
        spin_unlock_irqrestore(&sta->tx_filtered[ac].lock, flags);
        tmp = skb_queue_len(&pending);
        filtered += tmp - count;
        count = tmp;

        spin_lock_irqsave(&sta->ps_tx_buf[ac].lock, flags);
        skb_queue_splice_tail_init(&sta->ps_tx_buf[ac], &pending);
        spin_unlock_irqrestore(&sta->ps_tx_buf[ac].lock, flags);
        tmp = skb_queue_len(&pending);
        buffered += tmp - count;
    }

    ieee80211_add_pending_skbs_fn(local, &pending, clear_sta_ps_flags, sta);

    local->total_ps_buffered -= buffered;

    sta_info_recalc_tim(sta);

    ps_dbg(sdata,
           "STA %pM aid %d sending %d filtered/%d PS frames since STA not sleeping anymore\n",
           sta->sta.addr, sta->sta.aid, filtered, buffered);
}

static void ieee80211_send_null_response(struct ieee80211_sub_if_data *sdata,
                     struct sta_info *sta, int tid,
                     enum ieee80211_frame_release_type reason)
{
    struct ieee80211_local *local = sdata->local;
    struct ieee80211_qos_hdr *nullfunc;
    struct sk_buff *skb;
    int size = sizeof(*nullfunc);
    __le16 fc;
    bool qos = test_sta_flag(sta, WLAN_STA_WME);
    struct ieee80211_tx_info *info;

    if (qos) {
        fc = cpu_to_le16(IEEE80211_FTYPE_DATA |
                 IEEE80211_STYPE_QOS_NULLFUNC |
                 IEEE80211_FCTL_FROMDS);
    } else {
        size -= 2;
        fc = cpu_to_le16(IEEE80211_FTYPE_DATA |
                 IEEE80211_STYPE_NULLFUNC |
                 IEEE80211_FCTL_FROMDS);
    }

    skb = dev_alloc_skb(local->hw.extra_tx_headroom + size);
    if (!skb)
        return;

    skb_reserve(skb, local->hw.extra_tx_headroom);

    nullfunc = (void *) skb_put(skb, size);
    nullfunc->frame_control = fc;
    nullfunc->duration_id = 0;
    memcpy(nullfunc->addr1, sta->sta.addr, ETH_ALEN);
    memcpy(nullfunc->addr2, sdata->vif.addr, ETH_ALEN);
    memcpy(nullfunc->addr3, sdata->vif.addr, ETH_ALEN);

    skb->priority = tid;
    skb_set_queue_mapping(skb, ieee802_1d_to_ac[tid]);
    if (qos) {
        nullfunc->qos_ctrl = cpu_to_le16(tid);

        if (reason == IEEE80211_FRAME_RELEASE_UAPSD)
            nullfunc->qos_ctrl |=
                cpu_to_le16(IEEE80211_QOS_CTL_EOSP);
    }

    info = IEEE80211_SKB_CB(skb);

    /*
     * Tell TX path to send this frame even though the
     * STA may still remain is PS mode after this frame
     * exchange. Also set EOSP to indicate this packet
     * ends the poll/service period.
     */
    info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER |
               IEEE80211_TX_STATUS_EOSP |
               IEEE80211_TX_CTL_REQ_TX_STATUS;

    drv_allow_buffered_frames(local, sta, BIT(tid), 1, reason, false);

    ieee80211_xmit(sdata, skb);
}

static void
ieee80211_sta_ps_deliver_response(struct sta_info *sta,
                  int n_frames, u8 ignored_acs,
                  enum ieee80211_frame_release_type reason)
{
    struct ieee80211_sub_if_data *sdata = sta->sdata;
    struct ieee80211_local *local = sdata->local;
    bool found = false;
    bool more_data = false;
    int ac;
    unsigned long driver_release_tids = 0;
    struct sk_buff_head frames;

    /* Service or PS-Poll period starts */
    set_sta_flag(sta, WLAN_STA_SP);

    __skb_queue_head_init(&frames);

    /*
     * Get response frame(s) and more data bit for it.
     */
    for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
        unsigned long tids;

        if (ignored_acs & BIT(ac))
            continue;

        tids = ieee80211_tids_for_ac(ac);

        if (!found) {
            driver_release_tids = sta->driver_buffered_tids & tids;
            if (driver_release_tids) {
                found = true;
            } else {
                struct sk_buff *skb;

                while (n_frames > 0) {
                    skb = skb_dequeue(&sta->tx_filtered[ac]);
                    if (!skb) {
                        skb = skb_dequeue(
                            &sta->ps_tx_buf[ac]);
                        if (skb)
                            local->total_ps_buffered--;
                    }
                    if (!skb)
                        break;
                    n_frames--;
                    found = true;
                    __skb_queue_tail(&frames, skb);
                }
            }

            /*
             * If the driver has data on more than one TID then
             * certainly there's more data if we release just a
             * single frame now (from a single TID).
             */
            if (reason == IEEE80211_FRAME_RELEASE_PSPOLL &&
                hweight16(driver_release_tids) > 1) {
                more_data = true;
                driver_release_tids =
                    BIT(ffs(driver_release_tids) - 1);
                break;
            }
        }

        if (!skb_queue_empty(&sta->tx_filtered[ac]) ||
            !skb_queue_empty(&sta->ps_tx_buf[ac])) {
            more_data = true;
            break;
        }
    }

    if (!found) {
        int tid;

        /*
         * For PS-Poll, this can only happen due to a race condition
         * when we set the TIM bit and the station notices it, but
         * before it can poll for the frame we expire it.
         *
         * For uAPSD, this is said in the standard (11.2.1.5 h):
         *  At each unscheduled SP for a non-AP STA, the AP shall
         *  attempt to transmit at least one MSDU or MMPDU, but no
         *  more than the value specified in the Max SP Length field
         *  in the QoS Capability element from delivery-enabled ACs,
         *  that are destined for the non-AP STA.
         *
         * Since we have no other MSDU/MMPDU, transmit a QoS null frame.
         */

        /* This will evaluate to 1, 3, 5 or 7. */
        tid = 7 - ((ffs(~ignored_acs) - 1) << 1);

        ieee80211_send_null_response(sdata, sta, tid, reason);
        return;
    }

    if (!driver_release_tids) {
        struct sk_buff_head pending;
        struct sk_buff *skb;
        int num = 0;
        u16 tids = 0;

        skb_queue_head_init(&pending);

        while ((skb = __skb_dequeue(&frames))) {
            struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
            struct ieee80211_hdr *hdr = (void *) skb->data;
            u8 *qoshdr = NULL;

            num++;

            /*
             * Tell TX path to send this frame even though the
             * STA may still remain is PS mode after this frame
             * exchange.
             */
            info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER;

            /*
             * Use MoreData flag to indicate whether there are
             * more buffered frames for this STA
             */
            if (more_data || !skb_queue_empty(&frames))
                hdr->frame_control |=
                    cpu_to_le16(IEEE80211_FCTL_MOREDATA);
            else
                hdr->frame_control &=
                    cpu_to_le16(~IEEE80211_FCTL_MOREDATA);

            if (ieee80211_is_data_qos(hdr->frame_control) ||
                ieee80211_is_qos_nullfunc(hdr->frame_control))
                qoshdr = ieee80211_get_qos_ctl(hdr);

            /* end service period after last frame */
            if (skb_queue_empty(&frames)) {
                if (reason == IEEE80211_FRAME_RELEASE_UAPSD &&
                    qoshdr)
                    *qoshdr |= IEEE80211_QOS_CTL_EOSP;

                info->flags |= IEEE80211_TX_STATUS_EOSP |
                           IEEE80211_TX_CTL_REQ_TX_STATUS;
            }

            if (qoshdr)
                tids |= BIT(*qoshdr & IEEE80211_QOS_CTL_TID_MASK);
            else
                tids |= BIT(0);

            __skb_queue_tail(&pending, skb);
        }

        drv_allow_buffered_frames(local, sta, tids, num,
                      reason, more_data);

        ieee80211_add_pending_skbs(local, &pending);

        sta_info_recalc_tim(sta);
    } else {
        /*
         * We need to release a frame that is buffered somewhere in the
         * driver ... it'll have to handle that.
         * Note that, as per the comment above, it'll also have to see
         * if there is more than just one frame on the specific TID that
         * we're releasing from, and it needs to set the more-data bit
         * accordingly if we tell it that there's no more data. If we do
         * tell it there's more data, then of course the more-data bit
         * needs to be set anyway.
         */
        drv_release_buffered_frames(local, sta, driver_release_tids,
                        n_frames, reason, more_data);

        /*
         * Note that we don't recalculate the TIM bit here as it would
         * most likely have no effect at all unless the driver told us
         * that the TID became empty before returning here from the
         * release function.
         * Either way, however, when the driver tells us that the TID
         * became empty we'll do the TIM recalculation.
         */
    }
}

void ieee80211_sta_ps_deliver_poll_response(struct sta_info *sta)
{
    u8 ignore_for_response = sta->sta.uapsd_queues;

    /*
     * If all ACs are delivery-enabled then we should reply
     * from any of them, if only some are enabled we reply
     * only from the non-enabled ones.
     */
    if (ignore_for_response == BIT(IEEE80211_NUM_ACS) - 1)
        ignore_for_response = 0;

    ieee80211_sta_ps_deliver_response(sta, 1, ignore_for_response,
                      IEEE80211_FRAME_RELEASE_PSPOLL);
}

void ieee80211_sta_ps_deliver_uapsd(struct sta_info *sta)
{
    int n_frames = sta->sta.max_sp;
    u8 delivery_enabled = sta->sta.uapsd_queues;

    /*
     * If we ever grow support for TSPEC this might happen if
     * the TSPEC update from hostapd comes in between a trigger
     * frame setting WLAN_STA_UAPSD in the RX path and this
     * actually getting called.
     */
    if (!delivery_enabled)
        return;

    switch (sta->sta.max_sp) {
    case 1:
        n_frames = 2;
        break;
    case 2:
        n_frames = 4;
        break;
    case 3:
        n_frames = 6;
        break;
    case 0:
        /* XXX: what is a good value? */
        n_frames = 8;
        break;
    }

    ieee80211_sta_ps_deliver_response(sta, n_frames, ~delivery_enabled,
                      IEEE80211_FRAME_RELEASE_UAPSD);
}

void ieee80211_sta_block_awake(struct ieee80211_hw *hw,
                   struct ieee80211_sta *pubsta, bool block)
{
    struct sta_info *sta = container_of(pubsta, struct sta_info, sta);

    trace_api_sta_block_awake(sta->local, pubsta, block);

    if (block)
        set_sta_flag(sta, WLAN_STA_PS_DRIVER);
    else if (test_sta_flag(sta, WLAN_STA_PS_DRIVER))
        ieee80211_queue_work(hw, &sta->drv_unblock_wk);
}
EXPORT_SYMBOL(ieee80211_sta_block_awake);

void ieee80211_sta_eosp_irqsafe(struct ieee80211_sta *pubsta)
{
    struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
    struct ieee80211_local *local = sta->local;
    struct sk_buff *skb;
    struct skb_eosp_msg_data *data;

    trace_api_eosp(local, pubsta);

    skb = alloc_skb(0, GFP_ATOMIC);
    if (!skb) {
        /* too bad ... but race is better than loss */
        clear_sta_flag(sta, WLAN_STA_SP);
        return;
    }

    data = (void *)skb->cb;
    memcpy(data->sta, pubsta->addr, ETH_ALEN);
    memcpy(data->iface, sta->sdata->vif.addr, ETH_ALEN);
    skb->pkt_type = IEEE80211_EOSP_MSG;
    skb_queue_tail(&local->skb_queue, skb);
    tasklet_schedule(&local->tasklet);
}
EXPORT_SYMBOL(ieee80211_sta_eosp_irqsafe);

void ieee80211_sta_set_buffered(struct ieee80211_sta *pubsta,
                u8 tid, bool buffered)
{
    struct sta_info *sta = container_of(pubsta, struct sta_info, sta);

    if (WARN_ON(tid >= STA_TID_NUM))
        return;

    if (buffered)
        set_bit(tid, &sta->driver_buffered_tids);
    else
        clear_bit(tid, &sta->driver_buffered_tids);

    sta_info_recalc_tim(sta);
}
EXPORT_SYMBOL(ieee80211_sta_set_buffered);

int sta_info_move_state(struct sta_info *sta,
            enum ieee80211_sta_state new_state)
{
    might_sleep();

    if (sta->sta_state == new_state)
        return 0;

    /* check allowed transitions first */

    switch (new_state) {
    case IEEE80211_STA_NONE:
        if (sta->sta_state != IEEE80211_STA_AUTH)
            return -EINVAL;
        break;
    case IEEE80211_STA_AUTH:
        if (sta->sta_state != IEEE80211_STA_NONE &&
            sta->sta_state != IEEE80211_STA_ASSOC)
            return -EINVAL;
        break;
    case IEEE80211_STA_ASSOC:
        if (sta->sta_state != IEEE80211_STA_AUTH &&
            sta->sta_state != IEEE80211_STA_AUTHORIZED)
            return -EINVAL;
        break;
    case IEEE80211_STA_AUTHORIZED:
        if (sta->sta_state != IEEE80211_STA_ASSOC)
            return -EINVAL;
        break;
    default:
        WARN(1, "invalid state %d", new_state);
        return -EINVAL;
    }

    sta_dbg(sta->sdata, "moving STA %pM to state %d\n",
        sta->sta.addr, new_state);

    /*
     * notify the driver before the actual changes so it can
     * fail the transition
     */
    if (test_sta_flag(sta, WLAN_STA_INSERTED)) {
        int err = drv_sta_state(sta->local, sta->sdata, sta,
                    sta->sta_state, new_state);
        if (err)
            return err;
    }

    /* reflect the change in all state variables */

    switch (new_state) {
    case IEEE80211_STA_NONE:
        if (sta->sta_state == IEEE80211_STA_AUTH)
            clear_bit(WLAN_STA_AUTH, &sta->_flags);
        break;
    case IEEE80211_STA_AUTH:
        if (sta->sta_state == IEEE80211_STA_NONE)
            set_bit(WLAN_STA_AUTH, &sta->_flags);
        else if (sta->sta_state == IEEE80211_STA_ASSOC)
            clear_bit(WLAN_STA_ASSOC, &sta->_flags);
        break;
    case IEEE80211_STA_ASSOC:
        if (sta->sta_state == IEEE80211_STA_AUTH) {
            set_bit(WLAN_STA_ASSOC, &sta->_flags);
        } else if (sta->sta_state == IEEE80211_STA_AUTHORIZED) {
            if (sta->sdata->vif.type == NL80211_IFTYPE_AP ||
                (sta->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
                 !sta->sdata->u.vlan.sta))
                atomic_dec(&sta->sdata->bss->num_mcast_sta);
            clear_bit(WLAN_STA_AUTHORIZED, &sta->_flags);
        }
        break;
    case IEEE80211_STA_AUTHORIZED:
        if (sta->sta_state == IEEE80211_STA_ASSOC) {
            if (sta->sdata->vif.type == NL80211_IFTYPE_AP ||
                (sta->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
                 !sta->sdata->u.vlan.sta))
                atomic_inc(&sta->sdata->bss->num_mcast_sta);
            set_bit(WLAN_STA_AUTHORIZED, &sta->_flags);
        }
        break;
    default:
        break;
    }

    sta->sta_state = new_state;

    return 0;
}