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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>
#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"
/**
* 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.
*
* Upon allocating a STA info structure with sta_info_alloc(), the caller owns
* that structure. It must then either destroy it using sta_info_destroy()
* (which is pretty useless) or insert it into the hash table using
* sta_info_insert() which demotes the reference from ownership to a regular
* RCU-protected reference; if the function is called without protection by an
* RCU critical section the reference is instantly invalidated. 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.
*
* When the insertion fails (sta_info_insert()) returns non-zero), the
* structure will have been freed by sta_info_insert()!
*
* sta entries are added by mac80211 when you establish a link with a
* 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
* receive an assocation response from the AP. For IBSS this occurs when
* we receive a probe response or a beacon from target IBSS network. For
* WDS we add the sta for the peer imediately upon device open. When using
* AP mode we add stations for each respective station upon request from
* userspace through nl80211.
*
* Because there are debugfs entries for each station, and adding those
* must be able to sleep, it is also possible to "pin" a station entry,
* that means it can be removed from the hash table but not be freed.
* See the comment in __sta_info_unlink() for more information, this is
* an internal capability only.
*
* In order to remove a STA info structure, the caller needs to first
* unlink it (sta_info_unlink()) from the list and hash tables and
* then destroy it; sta_info_destroy() will wait for an RCU grace period
* to elapse before actually freeing it. Due to the pinning and the
* possibility of multiple callers trying to remove the same STA info at
* the same time, sta_info_unlink() can clear the STA info pointer it is
* passed to indicate that the STA info is owned by somebody else now.
*
* If sta_info_unlink() did not clear the pointer then the caller owns
* the STA info structure now and is responsible of destroying it with
* a call to sta_info_destroy().
*
* In all other cases, 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.
*/
/* Caller must hold local->sta_lock */
static int sta_info_hash_del(struct ieee80211_local *local,
struct sta_info *sta)
{
struct sta_info *s;
s = local->sta_hash[STA_HASH(sta->sta.addr)];
if (!s)
return -ENOENT;
if (s == sta) {
rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)],
s->hnext);
return 0;
}
while (s->hnext && s->hnext != sta)
s = s->hnext;
if (s->hnext) {
rcu_assign_pointer(s->hnext, sta->hnext);
return 0;
}
return -ENOENT;
}
/* protected by RCU */
struct sta_info *sta_info_get(struct ieee80211_local *local, const u8 *addr)
{
struct sta_info *sta;
sta = rcu_dereference(local->sta_hash[STA_HASH(addr)]);
while (sta) {
if (memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
break;
sta = rcu_dereference(sta->hnext);
}
return sta;
}
struct sta_info *sta_info_get_by_idx(struct ieee80211_local *local, int idx,
struct net_device *dev)
{
struct sta_info *sta;
int i = 0;
list_for_each_entry_rcu(sta, &local->sta_list, list) {
if (dev && dev != sta->sdata->dev)
continue;
if (i < idx) {
++i;
continue;
}
return sta;
}
return NULL;
}
/**
* __sta_info_free - internal STA free helper
*
* @local: pointer to the global information
* @sta: STA info to free
*
* This function must undo everything done by sta_info_alloc()
* that may happen before sta_info_insert().
*/
static void __sta_info_free(struct ieee80211_local *local,
struct sta_info *sta)
{
rate_control_free_sta(sta);
rate_control_put(sta->rate_ctrl);
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
printk(KERN_DEBUG "%s: Destroyed STA %pM\n",
wiphy_name(local->hw.wiphy), sta->sta.addr);
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
kfree(sta);
}
void sta_info_destroy(struct sta_info *sta)
{
struct ieee80211_local *local;
struct sk_buff *skb;
int i;
might_sleep();
if (!sta)
return;
local = sta->local;
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);
#endif
/*
* We have only unlinked the key, and actually destroying it
* may mean it is removed from hardware which requires that
* the key->sta pointer is still valid, so flush the key todo
* list here.
*
* ieee80211_key_todo() will synchronize_rcu() so after this
* nothing can reference this sta struct any more.
*/
ieee80211_key_todo();
#ifdef CONFIG_MAC80211_MESH
if (ieee80211_vif_is_mesh(&sta->sdata->vif))
del_timer_sync(&sta->plink_timer);
#endif
while ((skb = skb_dequeue(&sta->ps_tx_buf)) != NULL) {
local->total_ps_buffered--;
dev_kfree_skb_any(skb);
}
while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL)
dev_kfree_skb_any(skb);
for (i = 0; i < STA_TID_NUM; i++) {
struct tid_ampdu_rx *tid_rx;
struct tid_ampdu_tx *tid_tx;
spin_lock_bh(&sta->lock);
tid_rx = sta->ampdu_mlme.tid_rx[i];
/* Make sure timer won't free the tid_rx struct, see below */
if (tid_rx)
tid_rx->shutdown = true;
spin_unlock_bh(&sta->lock);
/*
* Outside spinlock - shutdown is true now so that the timer
* won't free tid_rx, we have to do that now. Can't let the
* timer do it because we have to sync the timer outside the
* lock that it takes itself.
*/
if (tid_rx) {
del_timer_sync(&tid_rx->session_timer);
kfree(tid_rx);
}
/*
* No need to do such complications for TX agg sessions, the
* path leading to freeing the tid_tx struct goes via a call
* from the driver, and thus needs to look up the sta struct
* again, which cannot be found when we get here. Hence, we
* just need to delete the timer and free the aggregation
* info; we won't be telling the peer about it then but that
* doesn't matter if we're not talking to it again anyway.
*/
tid_tx = sta->ampdu_mlme.tid_tx[i];
if (tid_tx) {
del_timer_sync(&tid_tx->addba_resp_timer);
/*
* STA removed while aggregation session being
* started? Bit odd, but purge frames anyway.
*/
skb_queue_purge(&tid_tx->pending);
kfree(tid_tx);
}
}
__sta_info_free(local, sta
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