mesh_plink.c

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/*
 * Copyright (c) 2008, 2009 open80211s Ltd.
 * Author:     Luis Carlos Cobo <luisca@cozybit.com>
 *
 * 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/gfp.h>
#include <linux/kernel.h>
#include <linux/random.h>
#include "ieee80211_i.h"
#include "rate.h"
#include "mesh.h"

#ifdef CONFIG_MAC80211_VERBOSE_MPL_DEBUG
#define mpl_dbg(fmt, args...)   printk(KERN_DEBUG fmt, ##args)
#else
#define mpl_dbg(fmt, args...)   do { (void)(0); } while (0)
#endif

#define PLINK_GET_LLID(p) (p + 2)
#define PLINK_GET_PLID(p) (p + 4)

#define mod_plink_timer(s, t) (mod_timer(&s->plink_timer, \
                                jiffies + HZ * t / 1000))

#define dot11MeshMaxRetries(s) (s->u.mesh.mshcfg.dot11MeshMaxRetries)
#define dot11MeshRetryTimeout(s) (s->u.mesh.mshcfg.dot11MeshRetryTimeout)
#define dot11MeshConfirmTimeout(s) (s->u.mesh.mshcfg.dot11MeshConfirmTimeout)
#define dot11MeshHoldingTimeout(s) (s->u.mesh.mshcfg.dot11MeshHoldingTimeout)
#define dot11MeshMaxPeerLinks(s) (s->u.mesh.mshcfg.dot11MeshMaxPeerLinks)

/* We only need a valid sta if user configured a minimum rssi_threshold. */
#define rssi_threshold_check(sta, sdata) \
                (sdata->u.mesh.mshcfg.rssi_threshold == 0 ||\
                (sta && (s8) -ewma_read(&sta->avg_signal) > \
                sdata->u.mesh.mshcfg.rssi_threshold))

enum plink_event {
        PLINK_UNDEFINED,
        OPN_ACPT,
        OPN_RJCT,
        OPN_IGNR,
        CNF_ACPT,
        CNF_RJCT,
        CNF_IGNR,
        CLS_ACPT,
        CLS_IGNR
};

static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
                enum ieee80211_self_protected_actioncode action,
                u8 *da, __le16 llid, __le16 plid, __le16 reason);

static inline
void mesh_plink_inc_estab_count(struct ieee80211_sub_if_data *sdata)
{
        atomic_inc(&sdata->u.mesh.mshstats.estab_plinks);
        mesh_accept_plinks_update(sdata);
}

static inline
void mesh_plink_dec_estab_count(struct ieee80211_sub_if_data *sdata)
{
        atomic_dec(&sdata->u.mesh.mshstats.estab_plinks);
        mesh_accept_plinks_update(sdata);
}

static inline void mesh_plink_fsm_restart(struct sta_info *sta)
{
        sta->plink_state = NL80211_PLINK_LISTEN;
        sta->llid = sta->plid = sta->reason = 0;
        sta->plink_retries = 0;
}

/*
 * Allocate mesh sta entry and insert into station table
 */
static struct sta_info *mesh_plink_alloc(struct ieee80211_sub_if_data *sdata,
                                         u8 *hw_addr)
{
        struct sta_info *sta;

        if (sdata->local->num_sta >= MESH_MAX_PLINKS)
                return NULL;

        sta = sta_info_alloc(sdata, hw_addr, GFP_KERNEL);
        if (!sta)
                return NULL;

        sta_info_pre_move_state(sta, IEEE80211_STA_AUTH);
        sta_info_pre_move_state(sta, IEEE80211_STA_ASSOC);
        sta_info_pre_move_state(sta, IEEE80211_STA_AUTHORIZED);

        set_sta_flag(sta, WLAN_STA_WME);

        return sta;
}

/*
 * mesh_set_ht_prot_mode - set correct HT protection mode
 *
 * Section 9.23.3.5 of IEEE 80211-2012 describes the protection rules for HT
 * mesh STA in a MBSS. Three HT protection modes are supported for now, non-HT
 * mixed mode, 20MHz-protection and no-protection mode. non-HT mixed mode is
 * selected if any non-HT peers are present in our MBSS.  20MHz-protection mode
 * is selected if all peers in our 20/40MHz MBSS support HT and atleast one
 * HT20 peer is present. Otherwise no-protection mode is selected.
 */
static u32 mesh_set_ht_prot_mode(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta;
        u32 changed = 0;
        u16 ht_opmode;
        bool non_ht_sta = false, ht20_sta = false;

        if (local->_oper_channel_type == NL80211_CHAN_NO_HT)
                return 0;

        rcu_read_lock();
        list_for_each_entry_rcu(sta, &local->sta_list, list) {
                if (sdata != sta->sdata ||
                    sta->plink_state != NL80211_PLINK_ESTAB)
                        continue;

                switch (sta->ch_type) {
                case NL80211_CHAN_NO_HT:
                        mpl_dbg("mesh_plink %pM: nonHT sta (%pM) is present",
                                sdata->vif.addr, sta->sta.addr);
                        non_ht_sta = true;
                        goto out;
                case NL80211_CHAN_HT20:
                        mpl_dbg("mesh_plink %pM: HT20 sta (%pM) is present",
                                sdata->vif.addr, sta->sta.addr);
                        ht20_sta = true;
                default:
                        break;
                }
        }
out:
        rcu_read_unlock();

        if (non_ht_sta)
                ht_opmode = IEEE80211_HT_OP_MODE_PROTECTION_NONHT_MIXED;
        else if (ht20_sta && local->_oper_channel_type > NL80211_CHAN_HT20)
                ht_opmode = IEEE80211_HT_OP_MODE_PROTECTION_20MHZ;
        else
                ht_opmode = IEEE80211_HT_OP_MODE_PROTECTION_NONE;

        if (sdata->vif.bss_conf.ht_operation_mode != ht_opmode) {
                sdata->vif.bss_conf.ht_operation_mode = ht_opmode;
                sdata->u.mesh.mshcfg.ht_opmode = ht_opmode;
                changed = BSS_CHANGED_HT;
                mpl_dbg("mesh_plink %pM: protection mode changed to %d",
                        sdata->vif.addr, ht_opmode);
        }

        return changed;
}

static bool __mesh_plink_deactivate(struct sta_info *sta)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;
        bool deactivated = false;

        if (sta->plink_state == NL80211_PLINK_ESTAB) {
                mesh_plink_dec_estab_count(sdata);
                deactivated = true;
        }
        sta->plink_state = NL80211_PLINK_BLOCKED;
        mesh_path_flush_by_nexthop(sta);

        return deactivated;
}

void mesh_plink_deactivate(struct sta_info *sta)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;
        bool deactivated;

        spin_lock_bh(&sta->lock);
        deactivated = __mesh_plink_deactivate(sta);
        sta->reason = cpu_to_le16(WLAN_REASON_MESH_PEER_CANCELED);
        mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
                            sta->sta.addr, sta->llid, sta->plid,
                            sta->reason);
        spin_unlock_bh(&sta->lock);

        if (deactivated)
                ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
}

static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
                enum ieee80211_self_protected_actioncode action,
                u8 *da, __le16 llid, __le16 plid, __le16 reason) {
        struct ieee80211_local *local = sdata->local;
        struct sk_buff *skb;
        struct ieee80211_mgmt *mgmt;
        bool include_plid = false;
        u16 peering_proto = 0;
        u8 *pos, ie_len = 4;
        int hdr_len = offsetof(struct ieee80211_mgmt, u.action.u.self_prot) +
                      sizeof(mgmt->u.action.u.self_prot);

        skb = dev_alloc_skb(local->tx_headroom +
                            hdr_len +
                            2 + /* capability info */
                            2 + /* AID */
                            2 + 8 + /* supported rates */
                            2 + (IEEE80211_MAX_SUPP_RATES - 8) +
                            2 + sdata->u.mesh.mesh_id_len +
                            2 + sizeof(struct ieee80211_meshconf_ie) +
                            2 + sizeof(struct ieee80211_ht_cap) +
                            2 + sizeof(struct ieee80211_ht_operation) +
                            2 + 8 + /* peering IE */
                            sdata->u.mesh.ie_len);
        if (!skb)
                return -1;
        skb_reserve(skb, local->tx_headroom);
        mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
        memset(mgmt, 0, hdr_len);
        mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                                          IEEE80211_STYPE_ACTION);
        memcpy(mgmt->da, da, ETH_ALEN);
        memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
        memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
        mgmt->u.action.category = WLAN_CATEGORY_SELF_PROTECTED;
        mgmt->u.action.u.self_prot.action_code = action;

        if (action != WLAN_SP_MESH_PEERING_CLOSE) {
                /* capability info */
                pos = skb_put(skb, 2);
                memset(pos, 0, 2);
                if (action == WLAN_SP_MESH_PEERING_CONFIRM) {
                        /* AID */
                        pos = skb_put(skb, 2);
                        memcpy(pos + 2, &plid, 2);
                }
                if (ieee80211_add_srates_ie(&sdata->vif, skb, true) ||
                    ieee80211_add_ext_srates_ie(&sdata->vif, skb, true) ||
                    mesh_add_rsn_ie(skb, sdata) ||
                    mesh_add_meshid_ie(skb, sdata) ||
                    mesh_add_meshconf_ie(skb, sdata))
                        return -1;
        } else {        /* WLAN_SP_MESH_PEERING_CLOSE */
                if (mesh_add_meshid_ie(skb, sdata))
                        return -1;
        }

        /* Add Mesh Peering Management element */
        switch (action) {
        case WLAN_SP_MESH_PEERING_OPEN:
                break;
        case WLAN_SP_MESH_PEERING_CONFIRM:
                ie_len += 2;
                include_plid = true;
                break;
        case WLAN_SP_MESH_PEERING_CLOSE:
                if (plid) {
                        ie_len += 2;
                        include_plid = true;
                }
                ie_len += 2;    /* reason code */
                break;
        default:
                return -EINVAL;
        }

        if (WARN_ON(skb_tailroom(skb) < 2 + ie_len))
                return -ENOMEM;

        pos = skb_put(skb, 2 + ie_len);
        *pos++ = WLAN_EID_PEER_MGMT;
        *pos++ = ie_len;
        memcpy(pos, &peering_proto, 2);
        pos += 2;
        memcpy(pos, &llid, 2);
        pos += 2;
        if (include_plid) {
                memcpy(pos, &plid, 2);
                pos += 2;
        }
        if (action == WLAN_SP_MESH_PEERING_CLOSE) {
                memcpy(pos, &reason, 2);
                pos += 2;
        }

        if (action != WLAN_SP_MESH_PEERING_CLOSE) {
                if (mesh_add_ht_cap_ie(skb, sdata) ||
                    mesh_add_ht_oper_ie(skb, sdata))
                        return -1;
        }

        if (mesh_add_vendor_ies(skb, sdata))
                return -1;

        ieee80211_tx_skb(sdata, skb);
        return 0;
}

/* mesh_peer_init - initialize new mesh peer and return resulting sta_info
 *
 * @sdata: local meshif
 * @addr: peer's address
 * @elems: IEs from beacon or mesh peering frame
 *
 * call under RCU
 */
static struct sta_info *mesh_peer_init(struct ieee80211_sub_if_data *sdata,
                                       u8 *addr,
                                       struct ieee802_11_elems *elems)
{
        struct ieee80211_local *local = sdata->local;
        enum ieee80211_band band = local->oper_channel->band;
        struct ieee80211_supported_band *sband;
        u32 rates, basic_rates = 0;
        struct sta_info *sta;
        bool insert = false;

        sband = local->hw.wiphy->bands[band];
        rates = ieee80211_sta_get_rates(local, elems, band, &basic_rates);

        sta = sta_info_get(sdata, addr);
        if (!sta) {
                /* Userspace handles peer allocation when security is enabled */
                if (sdata->u.mesh.security & IEEE80211_MESH_SEC_AUTHED) {
                        cfg80211_notify_new_peer_candidate(sdata->dev, addr,
                                                           elems->ie_start,
                                                           elems->total_len,
                                                           GFP_ATOMIC);
                        return NULL;
                }

                sta = mesh_plink_alloc(sdata, addr);
                if (!sta)
                        return NULL;
                insert = true;
        }

        spin_lock_bh(&sta->lock);
        sta->last_rx = jiffies;
        sta->sta.supp_rates[band] = rates;
        if (elems->ht_cap_elem &&
            sdata->local->_oper_channel_type != NL80211_CHAN_NO_HT)
                ieee80211_ht_cap_ie_to_sta_ht_cap(sdata, sband,
                                                  elems->ht_cap_elem,
                                                  &sta->sta.ht_cap);
        else
                memset(&sta->sta.ht_cap, 0, sizeof(sta->sta.ht_cap));

        if (elems->ht_operation) {
                if (!(elems->ht_operation->ht_param &
                      IEEE80211_HT_PARAM_CHAN_WIDTH_ANY))
                        sta->sta.ht_cap.cap &=
                                            ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
                sta->ch_type =
                        ieee80211_ht_oper_to_channel_type(elems->ht_operation);
        }

        rate_control_rate_init(sta);
        spin_unlock_bh(&sta->lock);

        if (insert && sta_info_insert(sta))
                return NULL;

        return sta;
}

void mesh_neighbour_update(struct ieee80211_sub_if_data *sdata,
                           u8 *hw_addr,
                           struct ieee802_11_elems *elems)
{
        struct sta_info *sta;

        rcu_read_lock();
        sta = mesh_peer_init(sdata, hw_addr, elems);
        if (!sta)
                goto out;

        if (mesh_peer_accepts_plinks(elems) &&
            sta->plink_state == NL80211_PLINK_LISTEN &&
            sdata->u.mesh.accepting_plinks &&
            sdata->u.mesh.mshcfg.auto_open_plinks &&
            rssi_threshold_check(sta, sdata))
                mesh_plink_open(sta);

out:
        rcu_read_unlock();
}

static void mesh_plink_timer(unsigned long data)
{
        struct sta_info *sta;
        __le16 llid, plid, reason;
        struct ieee80211_sub_if_data *sdata;

        /*
         * This STA is valid because sta_info_destroy() will
         * del_timer_sync() this timer after having made sure
         * it cannot be readded (by deleting the plink.)
         */
        sta = (struct sta_info *) data;

        if (sta->sdata->local->quiescing) {
                sta->plink_timer_was_running = true;
                return;
        }

        spin_lock_bh(&sta->lock);
        if (sta->ignore_plink_timer) {
                sta->ignore_plink_timer = false;
                spin_unlock_bh(&sta->lock);
                return;
        }
        mpl_dbg("Mesh plink timer for %pM fired on state %d\n",
                sta->sta.addr, sta->plink_state);
        reason = 0;
        llid = sta->llid;
        plid = sta->plid;
        sdata = sta->sdata;

        switch (sta->plink_state) {
        case NL80211_PLINK_OPN_RCVD:
        case NL80211_PLINK_OPN_SNT:
                /* retry timer */
                if (sta->plink_retries < dot11MeshMaxRetries(sdata)) {
                        u32 rand;
                        mpl_dbg("Mesh plink for %pM (retry, timeout): %d %d\n",
                                sta->sta.addr, sta->plink_retries,
                                sta->plink_timeout);
                        get_random_bytes(&rand, sizeof(u32));
                        sta->plink_timeout = sta->plink_timeout +
                                             rand % sta->plink_timeout;
                        ++sta->plink_retries;
                        mod_plink_timer(sta, sta->plink_timeout);
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_OPEN,
                                            sta->sta.addr, llid, 0, 0);
                        break;
                }
                reason = cpu_to_le16(WLAN_REASON_MESH_MAX_RETRIES);
                /* fall through on else */
        case NL80211_PLINK_CNF_RCVD:
                /* confirm timer */
                if (!reason)
                        reason = cpu_to_le16(WLAN_REASON_MESH_CONFIRM_TIMEOUT);
                sta->plink_state = NL80211_PLINK_HOLDING;
                mod_plink_timer(sta, dot11MeshHoldingTimeout(sdata));
                spin_unlock_bh(&sta->lock);
                mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
                                    sta->sta.addr, llid, plid, reason);
                break;
        case NL80211_PLINK_HOLDING:
                /* holding timer */
                del_timer(&sta->plink_timer);
                mesh_plink_fsm_restart(sta);
                spin_unlock_bh(&sta->lock);
                break;
        default:
                spin_unlock_bh(&sta->lock);
                break;
        }
}

#ifdef CONFIG_PM
void mesh_plink_quiesce(struct sta_info *sta)
{
        if (del_timer_sync(&sta->plink_timer))
                sta->plink_timer_was_running = true;
}

void mesh_plink_restart(struct sta_info *sta)
{
        if (sta->plink_timer_was_running) {
                add_timer(&sta->plink_timer);
                sta->plink_timer_was_running = false;
        }
}
#endif

static inline void mesh_plink_timer_set(struct sta_info *sta, int timeout)
{
        sta->plink_timer.expires = jiffies + (HZ * timeout / 1000);
        sta->plink_timer.data = (unsigned long) sta;
        sta->plink_timer.function = mesh_plink_timer;
        sta->plink_timeout = timeout;
        add_timer(&sta->plink_timer);
}

int mesh_plink_open(struct sta_info *sta)
{
        __le16 llid;
        struct ieee80211_sub_if_data *sdata = sta->sdata;

        if (!test_sta_flag(sta, WLAN_STA_AUTH))
                return -EPERM;

        spin_lock_bh(&sta->lock);
        get_random_bytes(&llid, 2);
        sta->llid = llid;
        if (sta->plink_state != NL80211_PLINK_LISTEN) {
                spin_unlock_bh(&sta->lock);
                return -EBUSY;
        }
        sta->plink_state = NL80211_PLINK_OPN_SNT;
        mesh_plink_timer_set(sta, dot11MeshRetryTimeout(sdata));
        spin_unlock_bh(&sta->lock);
        mpl_dbg("Mesh plink: starting establishment with %pM\n",
                sta->sta.addr);

        return mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_OPEN,
                                   sta->sta.addr, llid, 0, 0);
}

void mesh_plink_block(struct sta_info *sta)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;
        bool deactivated;

        spin_lock_bh(&sta->lock);
        deactivated = __mesh_plink_deactivate(sta);
        sta->plink_state = NL80211_PLINK_BLOCKED;
        spin_unlock_bh(&sta->lock);

        if (deactivated)
                ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
}


void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_mgmt *mgmt,
                         size_t len, struct ieee80211_rx_status *rx_status)
{
        struct ieee802_11_elems elems;
        struct sta_info *sta;
        enum plink_event event;
        enum ieee80211_self_protected_actioncode ftype;
        size_t baselen;
        bool matches_local = true;
        u8 ie_len;
        u8 *baseaddr;
        u32 changed = 0;
        __le16 plid, llid, reason;
#ifdef CONFIG_MAC80211_VERBOSE_MPL_DEBUG
        static const char *mplstates[] = {
                [NL80211_PLINK_LISTEN] = "LISTEN",
                [NL80211_PLINK_OPN_SNT] = "OPN-SNT",
                [NL80211_PLINK_OPN_RCVD] = "OPN-RCVD",
                [NL80211_PLINK_CNF_RCVD] = "CNF_RCVD",
                [NL80211_PLINK_ESTAB] = "ESTAB",
                [NL80211_PLINK_HOLDING] = "HOLDING",
                [NL80211_PLINK_BLOCKED] = "BLOCKED"
        };
#endif

        /* need action_code, aux */
        if (len < IEEE80211_MIN_ACTION_SIZE + 3)
                return;

        if (is_multicast_ether_addr(mgmt->da)) {
                mpl_dbg("Mesh plink: ignore frame from multicast address");
                return;
        }

        baseaddr = mgmt->u.action.u.self_prot.variable;
        baselen = (u8 *) mgmt->u.action.u.self_prot.variable - (u8 *) mgmt;
        if (mgmt->u.action.u.self_prot.action_code ==
                                                WLAN_SP_MESH_PEERING_CONFIRM) {
                baseaddr += 4;
                baselen += 4;
        }
        ieee802_11_parse_elems(baseaddr, len - baselen, &elems);
        if (!elems.peering) {
                mpl_dbg("Mesh plink: missing necessary peer link ie\n");
                return;
        }
        if (elems.rsn_len &&
                        sdata->u.mesh.security == IEEE80211_MESH_SEC_NONE) {
                mpl_dbg("Mesh plink: can't establish link with secure peer\n");
                return;
        }

        ftype = mgmt->u.action.u.self_prot.action_code;
        ie_len = elems.peering_len;
        if ((ftype == WLAN_SP_MESH_PEERING_OPEN && ie_len != 4) ||
            (ftype == WLAN_SP_MESH_PEERING_CONFIRM && ie_len != 6) ||
            (ftype == WLAN_SP_MESH_PEERING_CLOSE && ie_len != 6
                                                        && ie_len != 8)) {
                mpl_dbg("Mesh plink: incorrect plink ie length %d %d\n",
                    ftype, ie_len);
                return;
        }

        if (ftype != WLAN_SP_MESH_PEERING_CLOSE &&
                                (!elems.mesh_id || !elems.mesh_config)) {
                mpl_dbg("Mesh plink: missing necessary ie\n");
                return;
        }
        /* Note the lines below are correct, the llid in the frame is the plid
         * from the point of view of this host.
         */
        memcpy(&plid, PLINK_GET_LLID(elems.peering), 2);
        if (ftype == WLAN_SP_MESH_PEERING_CONFIRM ||
            (ftype == WLAN_SP_MESH_PEERING_CLOSE && ie_len == 8))
                memcpy(&llid, PLINK_GET_PLID(elems.peering), 2);

        rcu_read_lock();

        sta = sta_info_get(sdata, mgmt->sa);
        if (!sta && ftype != WLAN_SP_MESH_PEERING_OPEN) {
                mpl_dbg("Mesh plink: cls or cnf from unknown peer\n");
                rcu_read_unlock();
                return;
        }

        if (ftype == WLAN_SP_MESH_PEERING_OPEN &&
            !rssi_threshold_check(sta, sdata)) {
                mpl_dbg("Mesh plink: %pM does not meet rssi threshold\n",
                        mgmt->sa);
                rcu_read_unlock();
                return;
        }

        if (sta && !test_sta_flag(sta, WLAN_STA_AUTH)) {
                mpl_dbg("Mesh plink: Action frame from non-authed peer\n");
                rcu_read_unlock();
                return;
        }

        if (sta && sta->plink_state == NL80211_PLINK_BLOCKED) {
                rcu_read_unlock();
                return;
        }

        /* Now we will figure out the appropriate event... */
        event = PLINK_UNDEFINED;
        if (ftype != WLAN_SP_MESH_PEERING_CLOSE &&
            !mesh_matches_local(sdata, &elems)) {
                matches_local = false;
                switch (ftype) {
                case WLAN_SP_MESH_PEERING_OPEN:
                        event = OPN_RJCT;
                        break;
                case WLAN_SP_MESH_PEERING_CONFIRM:
                        event = CNF_RJCT;
                        break;
                default:
                        break;
                }
        }

        if (!sta && !matches_local) {
                rcu_read_unlock();
                reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
                llid = 0;
                mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
                                    mgmt->sa, llid, plid, reason);
                return;
        } else if (!sta) {
                /* ftype == WLAN_SP_MESH_PEERING_OPEN */
                if (!mesh_plink_free_count(sdata)) {
                        mpl_dbg("Mesh plink error: no more free plinks\n");
                        rcu_read_unlock();
                        return;
                }
                event = OPN_ACPT;
        } else if (matches_local) {
                switch (ftype) {
                case WLAN_SP_MESH_PEERING_OPEN:
                        if (!mesh_plink_free_count(sdata) ||
                            (sta->plid && sta->plid != plid))
                                event = OPN_IGNR;
                        else
                                event = OPN_ACPT;
                        break;
                case WLAN_SP_MESH_PEERING_CONFIRM:
                        if (!mesh_plink_free_count(sdata) ||
                            (sta->llid != llid || sta->plid != plid))
                                event = CNF_IGNR;
                        else
                                event = CNF_ACPT;
                        break;
                case WLAN_SP_MESH_PEERING_CLOSE:
                        if (sta->plink_state == NL80211_PLINK_ESTAB)
                                /* Do not check for llid or plid. This does not
                                 * follow the standard but since multiple plinks
                                 * per sta are not supported, it is necessary in
                                 * order to avoid a livelock when MP A sees an
                                 * establish peer link to MP B but MP B does not
                                 * see it. This can be caused by a timeout in
                                 * B's peer link establishment or B beign
                                 * restarted.
                                 */
                                event = CLS_ACPT;
                        else if (sta->plid != plid)
                                event = CLS_IGNR;
                        else if (ie_len == 7 && sta->llid != llid)
                                event = CLS_IGNR;
                        else
                                event = CLS_ACPT;
                        break;
                default:
                        mpl_dbg("Mesh plink: unknown frame subtype\n");
                        rcu_read_unlock();
                        return;
                }
        }

        if (event == OPN_ACPT) {
                /* allocate sta entry if necessary and update info */
                sta = mesh_peer_init(sdata, mgmt->sa, &elems);
                if (!sta) {
                        mpl_dbg("Mesh plink: failed to init peer!\n");
                        rcu_read_unlock();
                        return;
                }
        }

        mpl_dbg("Mesh plink (peer, state, llid, plid, event): %pM %s %d %d %d\n",
                mgmt->sa, mplstates[sta->plink_state],
                le16_to_cpu(sta->llid), le16_to_cpu(sta->plid),
                event);
        reason = 0;
        spin_lock_bh(&sta->lock);
        switch (sta->plink_state) {
                /* spin_unlock as soon as state is updated at each case */
        case NL80211_PLINK_LISTEN:
                switch (event) {
                case CLS_ACPT:
                        mesh_plink_fsm_restart(sta);
                        spin_unlock_bh(&sta->lock);
                        break;
                case OPN_ACPT:
                        sta->plink_state = NL80211_PLINK_OPN_RCVD;
                        sta->plid = plid;
                        get_random_bytes(&llid, 2);
                        sta->llid = llid;
                        mesh_plink_timer_set(sta, dot11MeshRetryTimeout(sdata));
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_frame_tx(sdata,
                                            WLAN_SP_MESH_PEERING_OPEN,
                                            sta->sta.addr, llid, 0, 0);
                        mesh_plink_frame_tx(sdata,
                                            WLAN_SP_MESH_PEERING_CONFIRM,
                                            sta->sta.addr, llid, plid, 0);
                        break;
                default:
                        spin_unlock_bh(&sta->lock);
                        break;
                }
                break;

        case NL80211_PLINK_OPN_SNT:
                switch (event) {
                case OPN_RJCT:
                case CNF_RJCT:
                        reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
                case CLS_ACPT:
                        if (!reason)
                                reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
                        sta->reason = reason;
                        sta->plink_state = NL80211_PLINK_HOLDING;
                        if (!mod_plink_timer(sta,
                                             dot11MeshHoldingTimeout(sdata)))
                                sta->ignore_plink_timer = true;

                        llid = sta->llid;
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_frame_tx(sdata,
                                            WLAN_SP_MESH_PEERING_CLOSE,
                                            sta->sta.addr, llid, plid, reason);
                        break;
                case OPN_ACPT:
                        /* retry timer is left untouched */
                        sta->plink_state = NL80211_PLINK_OPN_RCVD;
                        sta->plid = plid;
                        llid = sta->llid;
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_frame_tx(sdata,
                                            WLAN_SP_MESH_PEERING_CONFIRM,
                                            sta->sta.addr, llid, plid, 0);
                        break;
                case CNF_ACPT:
                        sta->plink_state = NL80211_PLINK_CNF_RCVD;
                        if (!mod_plink_timer(sta,
                                             dot11MeshConfirmTimeout(sdata)))
                                sta->ignore_plink_timer = true;

                        spin_unlock_bh(&sta->lock);
                        break;
                default:
                        spin_unlock_bh(&sta->lock);
                        break;
                }
                break;

        case NL80211_PLINK_OPN_RCVD:
                switch (event) {
                case OPN_RJCT:
                case CNF_RJCT:
                        reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
                case CLS_ACPT:
                        if (!reason)
                                reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
                        sta->reason = reason;
                        sta->plink_state = NL80211_PLINK_HOLDING;
                        if (!mod_plink_timer(sta,
                                             dot11MeshHoldingTimeout(sdata)))
                                sta->ignore_plink_timer = true;

                        llid = sta->llid;
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
                                            sta->sta.addr, llid, plid, reason);
                        break;
                case OPN_ACPT:
                        llid = sta->llid;
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_frame_tx(sdata,
                                            WLAN_SP_MESH_PEERING_CONFIRM,
                                            sta->sta.addr, llid, plid, 0);
                        break;
                case CNF_ACPT:
                        del_timer(&sta->plink_timer);
                        sta->plink_state = NL80211_PLINK_ESTAB;
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_inc_estab_count(sdata);
                        changed |= mesh_set_ht_prot_mode(sdata);
                        changed |= BSS_CHANGED_BEACON;
                        mpl_dbg("Mesh plink with %pM ESTABLISHED\n",
                                sta->sta.addr);
                        break;
                default:
                        spin_unlock_bh(&sta->lock);
                        break;
                }
                break;

        case NL80211_PLINK_CNF_RCVD:
                switch (event) {
                case OPN_RJCT:
                case CNF_RJCT:
                        reason = cpu_to_le16(WLAN_REASON_MESH_CONFIG);
                case CLS_ACPT:
                        if (!reason)
                                reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
                        sta->reason = reason;
                        sta->plink_state = NL80211_PLINK_HOLDING;
                        if (!mod_plink_timer(sta,
                                             dot11MeshHoldingTimeout(sdata)))
                                sta->ignore_plink_timer = true;

                        llid = sta->llid;
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_frame_tx(sdata,
                                            WLAN_SP_MESH_PEERING_CLOSE,
                                            sta->sta.addr, llid, plid, reason);
                        break;
                case OPN_ACPT:
                        del_timer(&sta->plink_timer);
                        sta->plink_state = NL80211_PLINK_ESTAB;
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_inc_estab_count(sdata);
                        changed |= mesh_set_ht_prot_mode(sdata);
                        changed |= BSS_CHANGED_BEACON;
                        mpl_dbg("Mesh plink with %pM ESTABLISHED\n",
                                sta->sta.addr);
                        mesh_plink_frame_tx(sdata,
                                            WLAN_SP_MESH_PEERING_CONFIRM,
                                            sta->sta.addr, llid, plid, 0);
                        break;
                default:
                        spin_unlock_bh(&sta->lock);
                        break;
                }
                break;

        case NL80211_PLINK_ESTAB:
                switch (event) {
                case CLS_ACPT:
                        reason = cpu_to_le16(WLAN_REASON_MESH_CLOSE);
                        sta->reason = reason;
                        __mesh_plink_deactivate(sta);
                        sta->plink_state = NL80211_PLINK_HOLDING;
                        llid = sta->llid;
                        mod_plink_timer(sta, dot11MeshHoldingTimeout(sdata));
                        spin_unlock_bh(&sta->lock);
                        changed |= mesh_set_ht_prot_mode(sdata);
                        changed |= BSS_CHANGED_BEACON;
                        mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
                                            sta->sta.addr, llid, plid, reason);
                        break;
                case OPN_ACPT:
                        llid = sta->llid;
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_frame_tx(sdata,
                                            WLAN_SP_MESH_PEERING_CONFIRM,
                                            sta->sta.addr, llid, plid, 0);
                        break;
                default:
                        spin_unlock_bh(&sta->lock);
                        break;
                }
                break;
        case NL80211_PLINK_HOLDING:
                switch (event) {
                case CLS_ACPT:
                        if (del_timer(&sta->plink_timer))
                                sta->ignore_plink_timer = 1;
                        mesh_plink_fsm_restart(sta);
                        spin_unlock_bh(&sta->lock);
                        break;
                case OPN_ACPT:
                case CNF_ACPT:
                case OPN_RJCT:
                case CNF_RJCT:
                        llid = sta->llid;
                        reason = sta->reason;
                        spin_unlock_bh(&sta->lock);
                        mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
                                            sta->sta.addr, llid, plid, reason);
                        break;
                default:
                        spin_unlock_bh(&sta->lock);
                }
                break;
        default:
                /* should not get here, PLINK_BLOCKED is dealt with at the
                 * beginning of the function
                 */
                spin_unlock_bh(&sta->lock);
                break;
        }

        rcu_read_unlock();

        if (changed)
                ieee80211_bss_info_change_notify(sdata, changed);
}