sta_info.c 37 KB
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/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
 *
 * 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/netdevice.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
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#include <linux/timer.h>
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#include <linux/rtnetlink.h>
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#include <net/mac80211.h>
#include "ieee80211_i.h"
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#include "driver-ops.h"
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#include "rate.h"
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#include "sta_info.h"
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#include "debugfs_sta.h"
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#include "mesh.h"
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#include "wme.h"
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/**
 * DOC: STA information lifetime rules
 *
 * STA info structures (&struct sta_info) are managed in a hash table
 * for faster lookup and a list for iteration. They are managed using
 * RCU, i.e. access to the list and hash table is protected by RCU.
 *
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 * Upon allocating a STA info structure with sta_info_alloc(), the caller
 * owns that structure. It must then insert it into the hash table using
 * either sta_info_insert() or sta_info_insert_rcu(); only in the latter
 * case (which acquires an rcu read section but must not be called from
 * within one) will the pointer still be valid after the call. Note that
 * the caller may not do much with the STA info before inserting it, in
 * particular, it may not start any mesh peer link management or add
 * encryption keys.
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 *
 * When the insertion fails (sta_info_insert()) returns non-zero), the
 * structure will have been freed by sta_info_insert()!
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 *
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 * Station entries are added by mac80211 when you establish a link with a
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 * peer. This means different things for the different type of interfaces
 * we support. For a regular station this mean we add the AP sta when we
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 * receive an association response from the AP. For IBSS this occurs when
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 * get to know about a peer on the same IBSS. For WDS we add the sta for
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 * the peer immediately upon device open. When using AP mode we add stations
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 * for each respective station upon request from userspace through nl80211.
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 *
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 * In order to remove a STA info structure, various sta_info_destroy_*()
 * calls are available.
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 *
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 * There is no concept of ownership on a STA entry, each structure is
 * owned by the global hash table/list until it is removed. All users of
 * the structure need to be RCU protected so that the structure won't be
 * freed before they are done using it.
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 */
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/* Caller must hold local->sta_mtx */
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static int sta_info_hash_del(struct ieee80211_local *local,
			     struct sta_info *sta)
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{
	struct sta_info *s;

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

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

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

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	sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
				    lockdep_is_held(&local->sta_mtx));
	while (sta) {
		if (sta->sdata == sdata && !sta->dummy &&
		    memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
			break;
		sta = rcu_dereference_check(sta->hnext,
					    lockdep_is_held(&local->sta_mtx));
	}
	return sta;
}

/* get a station info entry even if it is a dummy station*/
struct sta_info *sta_info_get_rx(struct ieee80211_sub_if_data *sdata,
			      const u8 *addr)
{
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta;

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	sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
				    lockdep_is_held(&local->sta_mtx));
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	while (sta) {
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		if (sta->sdata == sdata &&
		    memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
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			break;
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		sta = rcu_dereference_check(sta->hnext,
					    lockdep_is_held(&local->sta_mtx));
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	}
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	return sta;
}

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/*
 * 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;

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	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)) &&
		    !sta->dummy &&
		    memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
			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 (including dummy stations)
 */
struct sta_info *sta_info_get_bss_rx(struct ieee80211_sub_if_data *sdata,
				  const u8 *addr)
{
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta;

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	sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
				    lockdep_is_held(&local->sta_mtx));
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	while (sta) {
		if ((sta->sdata == sdata ||
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		     (sta->sdata->bss && sta->sdata->bss == sdata->bss)) &&
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		    memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
			break;
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		sta = rcu_dereference_check(sta->hnext,
					    lockdep_is_held(&local->sta_mtx));
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	}
	return sta;
}

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

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

	return NULL;
}
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/**
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 * sta_info_free - free STA
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 *
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 * @local: pointer to the global information
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 * @sta: STA info to free
 *
 * This function must undo everything done by sta_info_alloc()
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 * that may happen before sta_info_insert(). It may only be
 * called when sta_info_insert() has not been attempted (and
 * if that fails, the station is freed anyway.)
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 */
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void sta_info_free(struct ieee80211_local *local, struct sta_info *sta)
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{
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	if (sta->rate_ctrl) {
		rate_control_free_sta(sta);
		rate_control_put(sta->rate_ctrl);
	}
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#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
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	wiphy_debug(local->hw.wiphy, "Destroyed STA %pM\n", sta->sta.addr);
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#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */

	kfree(sta);
}

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

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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;

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	if (!test_sta_flag(sta, WLAN_STA_PS_STA))
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		ieee80211_sta_ps_deliver_wakeup(sta);
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	else if (test_and_clear_sta_flag(sta, WLAN_STA_PSPOLL)) {
		clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
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		local_bh_disable();
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		ieee80211_sta_ps_deliver_poll_response(sta);
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		local_bh_enable();
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	} else if (test_and_clear_sta_flag(sta, WLAN_STA_UAPSD)) {
		clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
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		local_bh_disable();
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		ieee80211_sta_ps_deliver_uapsd(sta);
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		local_bh_enable();
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	} else
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		clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
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}

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

	return 0;
}

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struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
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				const u8 *addr, gfp_t gfp)
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{
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	struct ieee80211_local *local = sdata->local;
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	struct sta_info *sta;
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	struct timespec uptime;
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	int i;
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	sta = kzalloc(sizeof(*sta) + local->hw.sta_data_size, gfp);
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	if (!sta)
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		return NULL;
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	spin_lock_init(&sta->lock);
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	INIT_WORK(&sta->drv_unblock_wk, sta_unblock);
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	INIT_WORK(&sta->ampdu_mlme.work, ieee80211_ba_session_work);
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	mutex_init(&sta->ampdu_mlme.mtx);
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	memcpy(sta->sta.addr, addr, ETH_ALEN);
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	sta->local = local;
	sta->sdata = sdata;
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	sta->last_rx = jiffies;
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	do_posix_clock_monotonic_gettime(&uptime);
	sta->last_connected = uptime.tv_sec;
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	ewma_init(&sta->avg_signal, 1024, 8);

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

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	for (i = 0; i < STA_TID_NUM; i++) {
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		/*
		 * 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.
		 */
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		sta->timer_to_tid[i] = i;
	}
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	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]);
	}
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	for (i = 0; i < NUM_RX_DATA_QUEUES; i++)
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		sta->last_seq_ctrl[i] = cpu_to_le16(USHRT_MAX);
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#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
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	wiphy_debug(local->hw.wiphy, "Allocated STA %pM\n", sta->sta.addr);
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#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */

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

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	return sta;
}

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

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	/*
	 * 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.
	 */
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	if (unlikely(!ieee80211_sdata_running(sdata)))
		return -ENETDOWN;
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	if (WARN_ON(compare_ether_addr(sta->sta.addr, sdata->vif.addr) == 0 ||
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		    is_multicast_ether_addr(sta->sta.addr)))
		return -EINVAL;

	return 0;
}

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

	lockdep_assert_held(&local->sta_mtx);
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	/*
	 * check if STA exists already.
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	 * only accept a scenario of a second call to sta_info_insert_finish
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	 * with a dummy station entry that was inserted earlier
	 * in that case - assume that the dummy station flag should
	 * be removed.
	 */
	exist_sta = sta_info_get_bss_rx(sdata, sta->sta.addr);
	if (exist_sta) {
		if (exist_sta == sta && sta->dummy) {
			dummy_reinsert = true;
		} else {
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			err = -EEXIST;
			goto out_err;
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		}
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	}
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	if (!sta->dummy || dummy_reinsert) {
		/* notify driver */
		err = drv_sta_add(local, sdata, &sta->sta);
		if (err) {
			if (sdata->vif.type != NL80211_IFTYPE_ADHOC)
				goto out_err;
			printk(KERN_DEBUG "%s: failed to add IBSS STA %pM to "
					  "driver (%d) - keeping it anyway.\n",
			       sdata->name, sta->sta.addr, err);
		} else
			sta->uploaded = true;
	}
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	if (!dummy_reinsert) {
		local->num_sta++;
		local->sta_generation++;
		smp_mb();

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

		list_add(&sta->list, &local->sta_list);
	} else {
		sta->dummy = false;
	}

	if (!sta->dummy) {
		struct station_info sinfo;

		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);
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	}
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#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
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	wiphy_debug(local->hw.wiphy, "Inserted %sSTA %pM\n",
			sta->dummy ? "dummy " : "", sta->sta.addr);
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#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */

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	/* move reference to rcu-protected */
	rcu_read_lock();
	mutex_unlock(&local->sta_mtx);
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	if (ieee80211_vif_is_mesh(&sdata->vif))
		mesh_accept_plinks_update(sdata);

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

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

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	might_sleep();

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

	mutex_lock(&local->sta_mtx);

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

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

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

	rcu_read_unlock();

	return err;
}

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/* Caller must hold sta->local->sta_mtx */
int sta_info_reinsert(struct sta_info *sta)
{
	struct ieee80211_local *local = sta->local;
	int err = 0;

	err = sta_info_insert_check(sta);
	if (err) {
		mutex_unlock(&local->sta_mtx);
		return err;
	}

	might_sleep();

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	err = sta_info_insert_finish(sta);
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	rcu_read_unlock();
	return err;
}

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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));
}

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static unsigned long ieee80211_tids_for_ac(int ac)
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{
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	/* 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;
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	}
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}

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void sta_info_recalc_tim(struct sta_info *sta)
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{
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	struct ieee80211_local *local = sta->local;
	struct ieee80211_if_ap *bss = sta->sdata->bss;
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	unsigned long flags;
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	bool indicate_tim = false;
	u8 ignore_for_tim = sta->sta.uapsd_queues;
	int ac;
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	if (WARN_ON_ONCE(!sta->sdata->bss))
		return;
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	/* No need to do anything if the driver does all */
	if (local->hw.flags & IEEE80211_HW_AP_LINK_PS)
		return;
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	if (sta->dead)
		goto done;
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	/*
	 * 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;
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		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;
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		tids = ieee80211_tids_for_ac(ac);

		indicate_tim |=
			sta->driver_buffered_tids & tids;
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	}
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 done:
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	spin_lock_irqsave(&local->tim_lock, flags);
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	if (indicate_tim)
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		__bss_tim_set(bss, sta->sta.aid);
	else
		__bss_tim_clear(bss, sta->sta.aid);
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	if (local->ops->set_tim) {
		local->tim_in_locked_section = true;
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		drv_set_tim(local, &sta->sta, indicate_tim);
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		local->tim_in_locked_section = false;
	}
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	spin_unlock_irqrestore(&local->tim_lock, flags);
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}

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

	if (!skb)
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		return false;
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	info = IEEE80211_SKB_CB(skb);
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	/* Timeout: (2 * listen_interval * beacon_int * 1024 / 1000000) sec */
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	timeout = (sta->listen_interval *
		   sta->sdata->vif.bss_conf.beacon_int *
		   32 / 15625) * HZ;
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	if (timeout < STA_TX_BUFFER_EXPIRE)
		timeout = STA_TX_BUFFER_EXPIRE;
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	return time_after(jiffies, info->control.jiffies + timeout);
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}


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

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	/*
	 * 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 (;;) {
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		spin_lock_irqsave(&sta->tx_filtered[ac].lock, flags);
		skb = skb_peek(&sta->tx_filtered[ac]);
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		if (sta_info_buffer_expired(sta, skb))
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			skb = __skb_dequeue(&sta->tx_filtered[ac]);
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		else
			skb = NULL;
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		spin_unlock_irqrestore(&sta->tx_filtered[ac].lock, flags);
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		/*
		 * 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;
		dev_kfree_skb(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.
	 */
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	for (;;) {
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		spin_lock_irqsave(&sta->ps_tx_buf[ac].lock, flags);
		skb = skb_peek(&sta->ps_tx_buf[ac]);
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		if (sta_info_buffer_expired(sta, skb))
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			skb = __skb_dequeue(&sta->ps_tx_buf[ac]);
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		else
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			skb = NULL;
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		spin_unlock_irqrestore(&sta->ps_tx_buf[ac].lock, flags);
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		/*
		 * 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
		 */
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		if (!skb)
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			break;
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		local->total_ps_buffered--;
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#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
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		printk(KERN_DEBUG "Buffered frame expired (STA %pM)\n",
		       sta->sta.addr);
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#endif
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		dev_kfree_skb(skb);
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	}
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	/*
	 * 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.
	 */
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	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;
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}

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static int __must_check __sta_info_destroy(struct sta_info *sta)
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{
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	struct ieee80211_local *local;
	struct ieee80211_sub_if_data *sdata;
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	int ret, i, ac;
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	struct tid_ampdu_tx *tid_tx;
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	might_sleep();
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	if (!sta)
		return -ENOENT;
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	local = sta->local;
	sdata = sta->sdata;
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	/*
	 * 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.
	 */
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	set_sta_flag(sta, WLAN_STA_BLOCK_BA);
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	ieee80211_sta_tear_down_BA_sessions(sta, true);
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	ret = sta_info_hash_del(local, sta);
	if (ret)
		return ret;

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	list_del(&sta->list);

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

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

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		clear_sta_flag(sta, WLAN_STA_PS_STA);
		clear_sta_flag(sta, WLAN_STA_PS_DRIVER);

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

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

	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
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		RCU_INIT_POINTER(sdata->u.vlan.sta, NULL);
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	while (sta->sta_state > IEEE80211_STA_NONE)
		sta_info_move_state(sta, sta->sta_state - 1);

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	if (sta->uploaded) {
		if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
			sdata = container_of(sdata->bss,
					     struct ieee80211_sub_if_data,
					     u.ap);
		drv_sta_remove(local, sdata, &sta->sta);
		sdata = sta->sdata;
	}

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	/*
	 * At this point, after we wait for an RCU grace period,
	 * 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.
	 */
	synchronize_rcu();

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	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
		local->total_ps_buffered -= skb_queue_len(&sta->ps_tx_buf[ac]);
		__skb_queue_purge(&sta->ps_tx_buf[ac]);
		__skb_queue_purge(&sta->tx_filtered[ac]);
	}
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#ifdef CONFIG_MAC80211_MESH
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	if (ieee80211_vif_is_mesh(&sdata->vif))
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		mesh_accept_plinks_update(sdata);
#endif

#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
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	wiphy_debug(local->hw.wiphy, "Removed STA %pM\n", sta->sta.addr);
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#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
	cancel_work_sync(&sta->drv_unblock_wk);

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

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	rate_control_remove_sta_debugfs(sta);
	ieee80211_sta_debugfs_remove(sta);

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

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	/* There could be some memory leaks because of ampdu tx pending queue
	 * not being freed before destroying the station info.
	 *
	 * Make sure that such queues are purged before freeing the station
	 * info.
	 * TODO: We have to somehow postpone the full destruction
	 * until the aggregation stop completes. Refer
	 * http://thread.gmane.org/gmane.linux.kernel.wireless.general/81936
	 */
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	mutex_lock(&sta->ampdu_mlme.mtx);

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	for (i = 0; i < STA_TID_NUM; i++) {
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		tid_tx = rcu_dereference_protected_tid_tx(sta, i);
		if (!tid_tx)
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			continue;
		if (skb_queue_len(&tid_tx->pending)) {
#ifdef CONFIG_MAC80211_HT_DEBUG
			wiphy_debug(local->hw.wiphy, "TX A-MPDU  purging %d "
				"packets for tid=%d\n",
				skb_queue_len(&tid_tx->pending), i);
#endif /* CONFIG_MAC80211_HT_DEBUG */
			__skb_queue_purge(&tid_tx->pending);
		}
		kfree_rcu(tid_tx, rcu_head);
	}

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	mutex_unlock(&sta->ampdu_mlme.mtx);

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	sta_info_free(local, sta);
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	return 0;
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}

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int sta_info_destroy_addr(struct ieee80211_sub_if_data *sdata, const u8 *addr)
851
{
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	struct sta_info *sta;
	int ret;
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	mutex_lock(&sdata->local->sta_mtx);
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	sta = sta_info_get_rx(sdata, addr);
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	ret = __sta_info_destroy(sta);
	mutex_unlock(&sdata->local->sta_mtx);
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	return ret;
}

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int sta_info_destroy_addr_bss(struct ieee80211_sub_if_data *sdata,
			      const u8 *addr)
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{
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	struct sta_info *sta;
	int ret;
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	mutex_lock(&sdata->local->sta_mtx);
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	sta = sta_info_get_bss_rx(sdata, addr);
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	ret = __sta_info_destroy(sta);
	mutex_unlock(&sdata->local->sta_mtx);
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	return ret;
}
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static void sta_info_cleanup(unsigned long data)
{
	struct ieee80211_local *local = (struct ieee80211_local *) data;
	struct sta_info *sta;
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	bool timer_needed = false;
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	rcu_read_lock();
	list_for_each_entry_rcu(sta, &local->sta_list, list)
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		if (sta_info_cleanup_expire_buffered(local, sta))
			timer_needed = true;
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	rcu_read_unlock();
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	if (local->quiescing)
		return;
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	if (!timer_needed)
		return;

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

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

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

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

/**
 * sta_info_flush - flush matching STA entries from the STA table
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 *
 * Returns the number of removed STA entries.
 *
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 * @local: local interface data
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 * @sdata: matching rule for the net device (sta->dev) or %NULL to match all STAs
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 */
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int sta_info_flush(struct ieee80211_local *local,
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		   struct ieee80211_sub_if_data *sdata)
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{
	struct sta_info *sta, *tmp;
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	int ret = 0;
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	might_sleep();
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	mutex_lock(&local->sta_mtx);
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	list_for_each_entry_safe(sta, tmp, &local->sta_list, list) {
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		if (!sdata || sdata == sta->sdata)
			WARN_ON(__sta_info_destroy(sta));
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	}
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	mutex_unlock(&local->sta_mtx);
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	return ret;
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}
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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;

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	mutex_lock(&local->sta_mtx);
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	list_for_each_entry_safe(sta, tmp, &local->sta_list, list)
		if (time_after(jiffies, sta->last_rx + exp_time)) {
#ifdef CONFIG_MAC80211_IBSS_DEBUG
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			printk(KERN_DEBUG "%s: expiring inactive STA %pM\n",
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			       sdata->name, sta->sta.addr);
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#endif
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			WARN_ON(__sta_info_destroy(sta));
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		}
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	mutex_unlock(&local->sta_mtx);
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