sta_info.c 40.3 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>
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#include <linux/etherdevice.h>
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#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_assign_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_assign_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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static void cleanup_single_sta(struct sta_info *sta)
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{
	int ac, i;
	struct tid_ampdu_tx *tid_tx;
	struct ieee80211_sub_if_data *sdata = sta->sdata;
	struct ieee80211_local *local = sdata->local;
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	struct ps_data *ps;
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	/*
	 * 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.
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	 *
	 * Note though that this still uses the sdata and even
	 * calls the driver in AP and mesh mode, so interfaces
	 * of those types mush use call sta_info_flush_cleanup()
	 * (typically via sta_info_flush()) before deconfiguring
	 * the driver.
	 *
	 * In station mode, nothing happens here so it doesn't
	 * have to (and doesn't) do that, this is intentional to
	 * speed up roaming.
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	 */

	if (test_sta_flag(sta, WLAN_STA_PS_STA)) {
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		if (sta->sdata->vif.type == NL80211_IFTYPE_AP ||
		    sta->sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
			ps = &sdata->bss->ps;
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		else if (ieee80211_vif_is_mesh(&sdata->vif))
			ps = &sdata->u.mesh.ps;
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		else
			return;
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		clear_sta_flag(sta, WLAN_STA_PS_STA);

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		atomic_dec(&ps->num_sta_ps);
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		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]);
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		ieee80211_purge_tx_queue(&local->hw, &sta->ps_tx_buf[ac]);
		ieee80211_purge_tx_queue(&local->hw, &sta->tx_filtered[ac]);
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	}

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	if (ieee80211_vif_is_mesh(&sdata->vif))
		mesh_sta_cleanup(sta);
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	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.
	 */
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	for (i = 0; i < IEEE80211_NUM_TIDS; i++) {
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		kfree(sta->ampdu_mlme.tid_start_tx[i]);
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		tid_tx = rcu_dereference_raw(sta->ampdu_mlme.tid_tx[i]);
		if (!tid_tx)
			continue;
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		ieee80211_purge_tx_queue(&local->hw, &tid_tx->pending);
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		kfree(tid_tx);
	}

	sta_info_free(local, sta);
}

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void ieee80211_cleanup_sdata_stas(struct ieee80211_sub_if_data *sdata)
{
	struct sta_info *sta;

	spin_lock_bh(&sdata->cleanup_stations_lock);
	while (!list_empty(&sdata->cleanup_stations)) {
		sta = list_first_entry(&sdata->cleanup_stations,
				       struct sta_info, list);
		list_del(&sta->list);
		spin_unlock_bh(&sdata->cleanup_stations_lock);

		cleanup_single_sta(sta);

		spin_lock_bh(&sdata->cleanup_stations_lock);
	}

	spin_unlock_bh(&sdata->cleanup_stations_lock);
}

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static void free_sta_rcu(struct rcu_head *h)
{
	struct sta_info *sta = container_of(h, struct sta_info, rcu_head);
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	struct ieee80211_sub_if_data *sdata = sta->sdata;
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	spin_lock(&sdata->cleanup_stations_lock);
	list_add_tail(&sta->list, &sdata->cleanup_stations);
	spin_unlock(&sdata->cleanup_stations_lock);

	ieee80211_queue_work(&sdata->local->hw, &sdata->cleanup_stations_wk);
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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));
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	while (sta) {
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		if (sta->sdata == sdata &&
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		    ether_addr_equal(sta->sta.addr, addr))
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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));
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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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		    ether_addr_equal(sta->sta.addr, addr))
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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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	}
	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)
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		rate_control_free_sta(sta);
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	sta_dbg(sta->sdata, "Destroyed STA %pM\n", sta->sta.addr);
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	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_assign_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)) {
		local_bh_disable();
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		ieee80211_sta_ps_deliver_wakeup(sta);
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		local_bh_enable();
	} else if (test_and_clear_sta_flag(sta, WLAN_STA_PSPOLL)) {
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		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;

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	sta->rate_ctrl = local->rate_ctrl;
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	sta->rate_ctrl_priv = rate_control_alloc_sta(sta->rate_ctrl,
						     &sta->sta, gfp);
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	if (!sta->rate_ctrl_priv)
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		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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#ifdef CONFIG_MAC80211_MESH
	if (ieee80211_vif_is_mesh(&sdata->vif) &&
	    !sdata->u.mesh.user_mpm)
		init_timer(&sta->plink_timer);
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	sta->nonpeer_pm = NL80211_MESH_POWER_ACTIVE;
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#endif
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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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	sta->sta_state = IEEE80211_STA_NONE;

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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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	for (i = 0; i < ARRAY_SIZE(sta->chain_signal_avg); i++)
		ewma_init(&sta->chain_signal_avg[i], 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 < IEEE80211_NUM_TIDS; 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 < IEEE80211_NUM_TIDS; i++)
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		sta->last_seq_ctrl[i] = cpu_to_le16(USHRT_MAX);
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	sta->sta.smps_mode = IEEE80211_SMPS_OFF;
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	if (sdata->vif.type == NL80211_IFTYPE_AP ||
	    sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
		struct ieee80211_supported_band *sband =
			local->hw.wiphy->bands[ieee80211_get_sdata_band(sdata)];
		u8 smps = (sband->ht_cap.cap & IEEE80211_HT_CAP_SM_PS) >>
				IEEE80211_HT_CAP_SM_PS_SHIFT;
		/*
		 * Assume that hostapd advertises our caps in the beacon and
		 * this is the known_smps_mode for a station that just assciated
		 */
		switch (smps) {
		case WLAN_HT_SMPS_CONTROL_DISABLED:
			sta->known_smps_mode = IEEE80211_SMPS_OFF;
			break;
		case WLAN_HT_SMPS_CONTROL_STATIC:
			sta->known_smps_mode = IEEE80211_SMPS_STATIC;
			break;
		case WLAN_HT_SMPS_CONTROL_DYNAMIC:
			sta->known_smps_mode = IEEE80211_SMPS_DYNAMIC;
			break;
		default:
			WARN_ON(1);
		}
	}
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	sta_dbg(sdata, "Allocated STA %pM\n", sta->sta.addr);
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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(ether_addr_equal(sta->sta.addr, sdata->vif.addr) ||
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		    is_multicast_ether_addr(sta->sta.addr)))
		return -EINVAL;

	return 0;
}

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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) {
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		/*
		 * 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;
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		return 0;
	}

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

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

	return err;
}

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/*
 * 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 station_info sinfo;
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	int err = 0;

	lockdep_assert_held(&local->sta_mtx);
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	/* check if STA exists already */
	if (sta_info_get_bss(sdata, sta->sta.addr)) {
		err = -EEXIST;
		goto out_err;
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	}
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	/* notify driver */
	err = sta_info_insert_drv_state(local, sdata, sta);
	if (err)
		goto out_err;
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	local->num_sta++;
	local->sta_generation++;
	smp_mb();
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	/* make the station visible */
	sta_info_hash_add(local, sta);
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	list_add_rcu(&sta->list, &local->sta_list);
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	set_sta_flag(sta, WLAN_STA_INSERTED);
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	ieee80211_sta_debugfs_add(sta);
	rate_control_add_sta_debugfs(sta);
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	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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	sta_dbg(sdata, "Inserted STA %pM\n", sta->sta.addr);
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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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static inline void __bss_tim_set(u8 *tim, u16 id)
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{
	/*
	 * This format has been mandated by the IEEE specifications,
	 * so this line may not be changed to use the __set_bit() format.
	 */
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	tim[id / 8] |= (1 << (id % 8));
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}

578
static inline void __bss_tim_clear(u8 *tim, u16 id)
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{
	/*
	 * This format has been mandated by the IEEE specifications,
	 * so this line may not be changed to use the __clear_bit() format.
	 */
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	tim[id / 8] &= ~(1 << (id % 8));
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}

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static inline bool __bss_tim_get(u8 *tim, u16 id)
{
	/*
	 * This format has been mandated by the IEEE specifications,
	 * so this line may not be changed to use the test_bit() format.
	 */
	return tim[id / 8] & (1 << (id % 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;
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	struct ps_data *ps;
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	bool indicate_tim = false;
	u8 ignore_for_tim = sta->sta.uapsd_queues;
	int ac;
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	u16 id;

	if (sta->sdata->vif.type == NL80211_IFTYPE_AP ||
	    sta->sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
		if (WARN_ON_ONCE(!sta->sdata->bss))
			return;
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		ps = &sta->sdata->bss->ps;
		id = sta->sta.aid;
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#ifdef CONFIG_MAC80211_MESH
	} else if (ieee80211_vif_is_mesh(&sta->sdata->vif)) {
		ps = &sta->sdata->u.mesh.ps;
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		/* TIM map only for 1 <= PLID <= IEEE80211_MAX_AID */
		id = le16_to_cpu(sta->plid) % (IEEE80211_MAX_AID + 1);
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#endif
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	} else {
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		return;
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	}
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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_bh(&local->tim_lock);
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	if (indicate_tim == __bss_tim_get(ps->tim, id))
		goto out_unlock;

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	if (indicate_tim)
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		__bss_tim_set(ps->tim, id);
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	else
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		__bss_tim_clear(ps->tim, id);
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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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out_unlock:
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	spin_unlock_bh(&local->tim_lock);
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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;
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		ieee80211_free_txskb(&local->hw, skb);
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	}

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

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	/* This is only necessary for stations on BSS/MBSS interfaces */
	if (!sta->sdata->bss &&
	    !ieee80211_vif_is_mesh(&sta->sdata->vif))
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		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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}

810
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;
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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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	lockdep_assert_held(&local->sta_mtx);

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

839
	list_del_rcu(&sta->list);
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	/* this always calls synchronize_net() */
	ieee80211_free_sta_keys(local, sta);
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	sta->dead = true;

	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) {
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		ret = sta_info_move_state(sta, sta->sta_state - 1);
		if (ret) {
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			WARN_ON_ONCE(1);
			break;
		}
	}
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	if (sta->uploaded) {
		ret = drv_sta_state(local, sdata, sta, IEEE80211_STA_NONE,
				    IEEE80211_STA_NOTEXIST);
		WARN_ON_ONCE(ret != 0);
	}
865

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

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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);

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	call_rcu(&sta->rcu_head, free_sta_rcu);
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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)
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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(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)
893
{
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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(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)
{
929
	spin_lock_init(&local->tim_lock);
930
	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)
{
939
	del_timer_sync(&local->sta_cleanup);
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}

942
943

int sta_info_flush_defer(struct ieee80211_sub_if_data *sdata)
944
{
945
	struct ieee80211_local *local = sdata->local;
946
	struct sta_info *sta, *tmp;
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	int ret = 0;
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949
	might_sleep();
950

951
	mutex_lock(&local->sta_mtx);
952
	list_for_each_entry_safe(sta, tmp, &local->sta_list, list) {
953
		if (sdata == sta->sdata) {
954
			WARN_ON(__sta_info_destroy(sta));
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			ret++;
		}
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	}
958
	mutex_unlock(&local->sta_mtx);
959

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	return ret;
}

void sta_info_flush_cleanup(struct ieee80211_sub_if_data *sdata)
{
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	ieee80211_cleanup_sdata_stas(sdata);
	cancel_work_sync(&sdata->cleanup_stations_wk);
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}
968

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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;

975
	mutex_lock(&local->sta_mtx);
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977

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

981
		if (time_after(jiffies, sta->last_rx + exp_time)) {
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			sta_dbg(sta->sdata, "expiring inactive STA %pM\n",
				sta->sta.addr);
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			if (ieee80211_vif_is_mesh(&sdata->vif) &&
			    test_sta_flag(sta, WLAN_STA_PS_STA))
				atomic_dec(&sdata->u.mesh.ps.num_sta_ps);

989
			WARN_ON(__sta_info_destroy(sta));
990
		}
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	}

993
	mutex_unlock(&local->sta_mtx);
994
}
995

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