networking: make skb_put & friends return void pointers

[GitHub/moto-9609/android_kernel_motorola_exynos9610.git] / net / mac80211 / mesh.c

/*
 * Copyright (c) 2008, 2009 open80211s Ltd.
 * Authors:    Luis Carlos Cobo <luisca@cozybit.com>
 *             Javier Cardona <javier@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/slab.h>
#include <asm/unaligned.h>
#include "ieee80211_i.h"
#include "mesh.h"
#include "driver-ops.h"

static int mesh_allocated;
static struct kmem_cache *rm_cache;

bool mesh_action_is_path_sel(struct ieee80211_mgmt *mgmt)
{
        return (mgmt->u.action.u.mesh_action.action_code ==
                        WLAN_MESH_ACTION_HWMP_PATH_SELECTION);
}

void ieee80211s_init(void)
{
        mesh_allocated = 1;
        rm_cache = kmem_cache_create("mesh_rmc", sizeof(struct rmc_entry),
                                     0, 0, NULL);
}

void ieee80211s_stop(void)
{
        if (!mesh_allocated)
                return;
        kmem_cache_destroy(rm_cache);
}

static void ieee80211_mesh_housekeeping_timer(unsigned long data)
{
        struct ieee80211_sub_if_data *sdata = (void *) data;
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;

        set_bit(MESH_WORK_HOUSEKEEPING, &ifmsh->wrkq_flags);

        ieee80211_queue_work(&local->hw, &sdata->work);
}

/**
 * mesh_matches_local - check if the config of a mesh point matches ours
 *
 * @sdata: local mesh subif
 * @ie: information elements of a management frame from the mesh peer
 *
 * This function checks if the mesh configuration of a mesh point matches the
 * local mesh configuration, i.e. if both nodes belong to the same mesh network.
 */
bool mesh_matches_local(struct ieee80211_sub_if_data *sdata,
                        struct ieee802_11_elems *ie)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        u32 basic_rates = 0;
        struct cfg80211_chan_def sta_chan_def;
        struct ieee80211_supported_band *sband;

        /*
         * As support for each feature is added, check for matching
         * - On mesh config capabilities
         *   - Power Save Support En
         *   - Sync support enabled
         *   - Sync support active
         *   - Sync support required from peer
         *   - MDA enabled
         * - Power management control on fc
         */
        if (!(ifmsh->mesh_id_len == ie->mesh_id_len &&
             memcmp(ifmsh->mesh_id, ie->mesh_id, ie->mesh_id_len) == 0 &&
             (ifmsh->mesh_pp_id == ie->mesh_config->meshconf_psel) &&
             (ifmsh->mesh_pm_id == ie->mesh_config->meshconf_pmetric) &&
             (ifmsh->mesh_cc_id == ie->mesh_config->meshconf_congest) &&
             (ifmsh->mesh_sp_id == ie->mesh_config->meshconf_synch) &&
             (ifmsh->mesh_auth_id == ie->mesh_config->meshconf_auth)))
                return false;

        sband = ieee80211_get_sband(sdata);
        if (!sband)
                return false;

        ieee80211_sta_get_rates(sdata, ie, sband->band,
                                &basic_rates);

        if (sdata->vif.bss_conf.basic_rates != basic_rates)
                return false;

        cfg80211_chandef_create(&sta_chan_def, sdata->vif.bss_conf.chandef.chan,
                                NL80211_CHAN_NO_HT);
        ieee80211_chandef_ht_oper(ie->ht_operation, &sta_chan_def);
        ieee80211_chandef_vht_oper(ie->vht_operation, &sta_chan_def);

        if (!cfg80211_chandef_compatible(&sdata->vif.bss_conf.chandef,
                                         &sta_chan_def))
                return false;

        return true;
}

/**
 * mesh_peer_accepts_plinks - check if an mp is willing to establish peer links
 *
 * @ie: information elements of a management frame from the mesh peer
 */
bool mesh_peer_accepts_plinks(struct ieee802_11_elems *ie)
{
        return (ie->mesh_config->meshconf_cap &
                        IEEE80211_MESHCONF_CAPAB_ACCEPT_PLINKS) != 0;
}

/**
 * mesh_accept_plinks_update - update accepting_plink in local mesh beacons
 *
 * @sdata: mesh interface in which mesh beacons are going to be updated
 *
 * Returns: beacon changed flag if the beacon content changed.
 */
u32 mesh_accept_plinks_update(struct ieee80211_sub_if_data *sdata)
{
        bool free_plinks;
        u32 changed = 0;

        /* In case mesh_plink_free_count > 0 and mesh_plinktbl_capacity == 0,
         * the mesh interface might be able to establish plinks with peers that
         * are already on the table but are not on PLINK_ESTAB state. However,
         * in general the mesh interface is not accepting peer link requests
         * from new peers, and that must be reflected in the beacon
         */
        free_plinks = mesh_plink_availables(sdata);

        if (free_plinks != sdata->u.mesh.accepting_plinks) {
                sdata->u.mesh.accepting_plinks = free_plinks;
                changed = BSS_CHANGED_BEACON;
        }

        return changed;
}

/*
 * mesh_sta_cleanup - clean up any mesh sta state
 *
 * @sta: mesh sta to clean up.
 */
void mesh_sta_cleanup(struct sta_info *sta)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;
        u32 changed = mesh_plink_deactivate(sta);

        if (changed)
                ieee80211_mbss_info_change_notify(sdata, changed);
}

int mesh_rmc_init(struct ieee80211_sub_if_data *sdata)
{
        int i;

        sdata->u.mesh.rmc = kmalloc(sizeof(struct mesh_rmc), GFP_KERNEL);
        if (!sdata->u.mesh.rmc)
                return -ENOMEM;
        sdata->u.mesh.rmc->idx_mask = RMC_BUCKETS - 1;
        for (i = 0; i < RMC_BUCKETS; i++)
                INIT_HLIST_HEAD(&sdata->u.mesh.rmc->bucket[i]);
        return 0;
}

void mesh_rmc_free(struct ieee80211_sub_if_data *sdata)
{
        struct mesh_rmc *rmc = sdata->u.mesh.rmc;
        struct rmc_entry *p;
        struct hlist_node *n;
        int i;

        if (!sdata->u.mesh.rmc)
                return;

        for (i = 0; i < RMC_BUCKETS; i++) {
                hlist_for_each_entry_safe(p, n, &rmc->bucket[i], list) {
                        hlist_del(&p->list);
                        kmem_cache_free(rm_cache, p);
                }
        }

        kfree(rmc);
        sdata->u.mesh.rmc = NULL;
}

/**
 * mesh_rmc_check - Check frame in recent multicast cache and add if absent.
 *
 * @sdata:      interface
 * @sa:         source address
 * @mesh_hdr:   mesh_header
 *
 * Returns: 0 if the frame is not in the cache, nonzero otherwise.
 *
 * Checks using the source address and the mesh sequence number if we have
 * received this frame lately. If the frame is not in the cache, it is added to
 * it.
 */
int mesh_rmc_check(struct ieee80211_sub_if_data *sdata,
                   const u8 *sa, struct ieee80211s_hdr *mesh_hdr)
{
        struct mesh_rmc *rmc = sdata->u.mesh.rmc;
        u32 seqnum = 0;
        int entries = 0;
        u8 idx;
        struct rmc_entry *p;
        struct hlist_node *n;

        if (!rmc)
                return -1;

        /* Don't care about endianness since only match matters */
        memcpy(&seqnum, &mesh_hdr->seqnum, sizeof(mesh_hdr->seqnum));
        idx = le32_to_cpu(mesh_hdr->seqnum) & rmc->idx_mask;
        hlist_for_each_entry_safe(p, n, &rmc->bucket[idx], list) {
                ++entries;
                if (time_after(jiffies, p->exp_time) ||
                    entries == RMC_QUEUE_MAX_LEN) {
                        hlist_del(&p->list);
                        kmem_cache_free(rm_cache, p);
                        --entries;
                } else if ((seqnum == p->seqnum) && ether_addr_equal(sa, p->sa))
                        return -1;
        }

        p = kmem_cache_alloc(rm_cache, GFP_ATOMIC);
        if (!p)
                return 0;

        p->seqnum = seqnum;
        p->exp_time = jiffies + RMC_TIMEOUT;
        memcpy(p->sa, sa, ETH_ALEN);
        hlist_add_head(&p->list, &rmc->bucket[idx]);
        return 0;
}

int mesh_add_meshconf_ie(struct ieee80211_sub_if_data *sdata,
                         struct sk_buff *skb)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        u8 *pos, neighbors;
        u8 meshconf_len = sizeof(struct ieee80211_meshconf_ie);

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

        pos = skb_put(skb, 2 + meshconf_len);
        *pos++ = WLAN_EID_MESH_CONFIG;
        *pos++ = meshconf_len;

        /* save a pointer for quick updates in pre-tbtt */
        ifmsh->meshconf_offset = pos - skb->data;

        /* Active path selection protocol ID */
        *pos++ = ifmsh->mesh_pp_id;
        /* Active path selection metric ID   */
        *pos++ = ifmsh->mesh_pm_id;
        /* Congestion control mode identifier */
        *pos++ = ifmsh->mesh_cc_id;
        /* Synchronization protocol identifier */
        *pos++ = ifmsh->mesh_sp_id;
        /* Authentication Protocol identifier */
        *pos++ = ifmsh->mesh_auth_id;
        /* Mesh Formation Info - number of neighbors */
        neighbors = atomic_read(&ifmsh->estab_plinks);
        neighbors = min_t(int, neighbors, IEEE80211_MAX_MESH_PEERINGS);
        *pos++ = neighbors << 1;
        /* Mesh capability */
        *pos = 0x00;
        *pos |= ifmsh->mshcfg.dot11MeshForwarding ?
                        IEEE80211_MESHCONF_CAPAB_FORWARDING : 0x00;
        *pos |= ifmsh->accepting_plinks ?
                        IEEE80211_MESHCONF_CAPAB_ACCEPT_PLINKS : 0x00;
        /* Mesh PS mode. See IEEE802.11-2012 8.4.2.100.8 */
        *pos |= ifmsh->ps_peers_deep_sleep ?
                        IEEE80211_MESHCONF_CAPAB_POWER_SAVE_LEVEL : 0x00;
        return 0;
}

int mesh_add_meshid_ie(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        u8 *pos;

        if (skb_tailroom(skb) < 2 + ifmsh->mesh_id_len)
                return -ENOMEM;

        pos = skb_put(skb, 2 + ifmsh->mesh_id_len);
        *pos++ = WLAN_EID_MESH_ID;
        *pos++ = ifmsh->mesh_id_len;
        if (ifmsh->mesh_id_len)
                memcpy(pos, ifmsh->mesh_id, ifmsh->mesh_id_len);

        return 0;
}

static int mesh_add_awake_window_ie(struct ieee80211_sub_if_data *sdata,
                                    struct sk_buff *skb)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        u8 *pos;

        /* see IEEE802.11-2012 13.14.6 */
        if (ifmsh->ps_peers_light_sleep == 0 &&
            ifmsh->ps_peers_deep_sleep == 0 &&
            ifmsh->nonpeer_pm == NL80211_MESH_POWER_ACTIVE)
                return 0;

        if (skb_tailroom(skb) < 4)
                return -ENOMEM;

        pos = skb_put(skb, 2 + 2);
        *pos++ = WLAN_EID_MESH_AWAKE_WINDOW;
        *pos++ = 2;
        put_unaligned_le16(ifmsh->mshcfg.dot11MeshAwakeWindowDuration, pos);

        return 0;
}

int mesh_add_vendor_ies(struct ieee80211_sub_if_data *sdata,
                        struct sk_buff *skb)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        u8 offset, len;
        const u8 *data;

        if (!ifmsh->ie || !ifmsh->ie_len)
                return 0;

        /* fast-forward to vendor IEs */
        offset = ieee80211_ie_split_vendor(ifmsh->ie, ifmsh->ie_len, 0);

        if (offset < ifmsh->ie_len) {
                len = ifmsh->ie_len - offset;
                data = ifmsh->ie + offset;
                if (skb_tailroom(skb) < len)
                        return -ENOMEM;
                skb_put_data(skb, data, len);
        }

        return 0;
}

int mesh_add_rsn_ie(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        u8 len = 0;
        const u8 *data;

        if (!ifmsh->ie || !ifmsh->ie_len)
                return 0;

        /* find RSN IE */
        data = cfg80211_find_ie(WLAN_EID_RSN, ifmsh->ie, ifmsh->ie_len);
        if (!data)
                return 0;

        len = data[1] + 2;

        if (skb_tailroom(skb) < len)
                return -ENOMEM;
        skb_put_data(skb, data, len);

        return 0;
}

static int mesh_add_ds_params_ie(struct ieee80211_sub_if_data *sdata,
                                 struct sk_buff *skb)
{
        struct ieee80211_chanctx_conf *chanctx_conf;
        struct ieee80211_channel *chan;
        u8 *pos;

        if (skb_tailroom(skb) < 3)
                return -ENOMEM;

        rcu_read_lock();
        chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
        if (WARN_ON(!chanctx_conf)) {
                rcu_read_unlock();
                return -EINVAL;
        }
        chan = chanctx_conf->def.chan;
        rcu_read_unlock();

        pos = skb_put(skb, 2 + 1);
        *pos++ = WLAN_EID_DS_PARAMS;
        *pos++ = 1;
        *pos++ = ieee80211_frequency_to_channel(chan->center_freq);

        return 0;
}

int mesh_add_ht_cap_ie(struct ieee80211_sub_if_data *sdata,
                       struct sk_buff *skb)
{
        struct ieee80211_supported_band *sband;
        u8 *pos;

        sband = ieee80211_get_sband(sdata);
        if (!sband)
                return -EINVAL;

        if (!sband->ht_cap.ht_supported ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_20_NOHT ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_5 ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_10)
                return 0;

        if (skb_tailroom(skb) < 2 + sizeof(struct ieee80211_ht_cap))
                return -ENOMEM;

        pos = skb_put(skb, 2 + sizeof(struct ieee80211_ht_cap));
        ieee80211_ie_build_ht_cap(pos, &sband->ht_cap, sband->ht_cap.cap);

        return 0;
}

int mesh_add_ht_oper_ie(struct ieee80211_sub_if_data *sdata,
                        struct sk_buff *skb)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_chanctx_conf *chanctx_conf;
        struct ieee80211_channel *channel;
        struct ieee80211_supported_band *sband;
        struct ieee80211_sta_ht_cap *ht_cap;
        u8 *pos;

        rcu_read_lock();
        chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
        if (WARN_ON(!chanctx_conf)) {
                rcu_read_unlock();
                return -EINVAL;
        }
        channel = chanctx_conf->def.chan;
        rcu_read_unlock();

        sband = local->hw.wiphy->bands[channel->band];
        ht_cap = &sband->ht_cap;

        if (!ht_cap->ht_supported ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_20_NOHT ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_5 ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_10)
                return 0;

        if (skb_tailroom(skb) < 2 + sizeof(struct ieee80211_ht_operation))
                return -ENOMEM;

        pos = skb_put(skb, 2 + sizeof(struct ieee80211_ht_operation));
        ieee80211_ie_build_ht_oper(pos, ht_cap, &sdata->vif.bss_conf.chandef,
                                   sdata->vif.bss_conf.ht_operation_mode,
                                   false);

        return 0;
}

int mesh_add_vht_cap_ie(struct ieee80211_sub_if_data *sdata,
                        struct sk_buff *skb)
{
        struct ieee80211_supported_band *sband;
        u8 *pos;

        sband = ieee80211_get_sband(sdata);
        if (!sband)
                return -EINVAL;

        if (!sband->vht_cap.vht_supported ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_20_NOHT ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_5 ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_10)
                return 0;

        if (skb_tailroom(skb) < 2 + sizeof(struct ieee80211_vht_cap))
                return -ENOMEM;

        pos = skb_put(skb, 2 + sizeof(struct ieee80211_vht_cap));
        ieee80211_ie_build_vht_cap(pos, &sband->vht_cap, sband->vht_cap.cap);

        return 0;
}

int mesh_add_vht_oper_ie(struct ieee80211_sub_if_data *sdata,
                         struct sk_buff *skb)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_chanctx_conf *chanctx_conf;
        struct ieee80211_channel *channel;
        struct ieee80211_supported_band *sband;
        struct ieee80211_sta_vht_cap *vht_cap;
        u8 *pos;

        rcu_read_lock();
        chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
        if (WARN_ON(!chanctx_conf)) {
                rcu_read_unlock();
                return -EINVAL;
        }
        channel = chanctx_conf->def.chan;
        rcu_read_unlock();

        sband = local->hw.wiphy->bands[channel->band];
        vht_cap = &sband->vht_cap;

        if (!vht_cap->vht_supported ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_20_NOHT ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_5 ||
            sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_10)
                return 0;

        if (skb_tailroom(skb) < 2 + sizeof(struct ieee80211_vht_operation))
                return -ENOMEM;

        pos = skb_put(skb, 2 + sizeof(struct ieee80211_vht_operation));
        ieee80211_ie_build_vht_oper(pos, vht_cap,
                                    &sdata->vif.bss_conf.chandef);

        return 0;
}

static void ieee80211_mesh_path_timer(unsigned long data)
{
        struct ieee80211_sub_if_data *sdata =
                (struct ieee80211_sub_if_data *) data;

        ieee80211_queue_work(&sdata->local->hw, &sdata->work);
}

static void ieee80211_mesh_path_root_timer(unsigned long data)
{
        struct ieee80211_sub_if_data *sdata =
                (struct ieee80211_sub_if_data *) data;
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;

        set_bit(MESH_WORK_ROOT, &ifmsh->wrkq_flags);

        ieee80211_queue_work(&sdata->local->hw, &sdata->work);
}

void ieee80211_mesh_root_setup(struct ieee80211_if_mesh *ifmsh)
{
        if (ifmsh->mshcfg.dot11MeshHWMPRootMode > IEEE80211_ROOTMODE_ROOT)
                set_bit(MESH_WORK_ROOT, &ifmsh->wrkq_flags);
        else {
                clear_bit(MESH_WORK_ROOT, &ifmsh->wrkq_flags);
                /* stop running timer */
                del_timer_sync(&ifmsh->mesh_path_root_timer);
        }
}

/**
 * ieee80211_fill_mesh_addresses - fill addresses of a locally originated mesh frame
 * @hdr:        802.11 frame header
 * @fc:         frame control field
 * @meshda:     destination address in the mesh
 * @meshsa:     source address address in the mesh.  Same as TA, as frame is
 *              locally originated.
 *
 * Return the length of the 802.11 (does not include a mesh control header)
 */
int ieee80211_fill_mesh_addresses(struct ieee80211_hdr *hdr, __le16 *fc,
                                  const u8 *meshda, const u8 *meshsa)
{
        if (is_multicast_ether_addr(meshda)) {
                *fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS);
                /* DA TA SA */
                memcpy(hdr->addr1, meshda, ETH_ALEN);
                memcpy(hdr->addr2, meshsa, ETH_ALEN);
                memcpy(hdr->addr3, meshsa, ETH_ALEN);
                return 24;
        } else {
                *fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS);
                /* RA TA DA SA */
                eth_zero_addr(hdr->addr1);   /* RA is resolved later */
                memcpy(hdr->addr2, meshsa, ETH_ALEN);
                memcpy(hdr->addr3, meshda, ETH_ALEN);
                memcpy(hdr->addr4, meshsa, ETH_ALEN);
                return 30;
        }
}

/**
 * ieee80211_new_mesh_header - create a new mesh header
 * @sdata:      mesh interface to be used
 * @meshhdr:    uninitialized mesh header
 * @addr4or5:   1st address in the ae header, which may correspond to address 4
 *              (if addr6 is NULL) or address 5 (if addr6 is present). It may
 *              be NULL.
 * @addr6:      2nd address in the ae header, which corresponds to addr6 of the
 *              mesh frame
 *
 * Return the header length.
 */
unsigned int ieee80211_new_mesh_header(struct ieee80211_sub_if_data *sdata,
                                       struct ieee80211s_hdr *meshhdr,
                                       const char *addr4or5, const char *addr6)
{
        if (WARN_ON(!addr4or5 && addr6))
                return 0;

        memset(meshhdr, 0, sizeof(*meshhdr));

        meshhdr->ttl = sdata->u.mesh.mshcfg.dot11MeshTTL;

        /* FIXME: racy -- TX on multiple queues can be concurrent */
        put_unaligned(cpu_to_le32(sdata->u.mesh.mesh_seqnum), &meshhdr->seqnum);
        sdata->u.mesh.mesh_seqnum++;

        if (addr4or5 && !addr6) {
                meshhdr->flags |= MESH_FLAGS_AE_A4;
                memcpy(meshhdr->eaddr1, addr4or5, ETH_ALEN);
                return 2 * ETH_ALEN;
        } else if (addr4or5 && addr6) {
                meshhdr->flags |= MESH_FLAGS_AE_A5_A6;
                memcpy(meshhdr->eaddr1, addr4or5, ETH_ALEN);
                memcpy(meshhdr->eaddr2, addr6, ETH_ALEN);
                return 3 * ETH_ALEN;
        }

        return ETH_ALEN;
}

static void ieee80211_mesh_housekeeping(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        u32 changed;

        if (ifmsh->mshcfg.plink_timeout > 0)
                ieee80211_sta_expire(sdata, ifmsh->mshcfg.plink_timeout * HZ);
        mesh_path_expire(sdata);

        changed = mesh_accept_plinks_update(sdata);
        ieee80211_mbss_info_change_notify(sdata, changed);

        mod_timer(&ifmsh->housekeeping_timer,
                  round_jiffies(jiffies +
                                IEEE80211_MESH_HOUSEKEEPING_INTERVAL));
}

static void ieee80211_mesh_rootpath(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        u32 interval;

        mesh_path_tx_root_frame(sdata);

        if (ifmsh->mshcfg.dot11MeshHWMPRootMode == IEEE80211_PROACTIVE_RANN)
                interval = ifmsh->mshcfg.dot11MeshHWMPRannInterval;
        else
                interval = ifmsh->mshcfg.dot11MeshHWMProotInterval;

        mod_timer(&ifmsh->mesh_path_root_timer,
                  round_jiffies(TU_TO_EXP_TIME(interval)));
}

static int
ieee80211_mesh_build_beacon(struct ieee80211_if_mesh *ifmsh)
{
        struct beacon_data *bcn;
        int head_len, tail_len;
        struct sk_buff *skb;
        struct ieee80211_mgmt *mgmt;
        struct ieee80211_chanctx_conf *chanctx_conf;
        struct mesh_csa_settings *csa;
        enum nl80211_band band;
        u8 *pos;
        struct ieee80211_sub_if_data *sdata;
        int hdr_len = offsetof(struct ieee80211_mgmt, u.beacon) +
                      sizeof(mgmt->u.beacon);

        sdata = container_of(ifmsh, struct ieee80211_sub_if_data, u.mesh);
        rcu_read_lock();
        chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
        band = chanctx_conf->def.chan->band;
        rcu_read_unlock();

        head_len = hdr_len +
                   2 + /* NULL SSID */
                   /* Channel Switch Announcement */
                   2 + sizeof(struct ieee80211_channel_sw_ie) +
                   /* Mesh Channel Switch Parameters */
                   2 + sizeof(struct ieee80211_mesh_chansw_params_ie) +
                   /* Channel Switch Wrapper + Wide Bandwidth CSA IE */
                   2 + 2 + sizeof(struct ieee80211_wide_bw_chansw_ie) +
                   2 + sizeof(struct ieee80211_sec_chan_offs_ie) +
                   2 + 8 + /* supported rates */
                   2 + 3; /* DS params */
        tail_len = 2 + (IEEE80211_MAX_SUPP_RATES - 8) +
                   2 + sizeof(struct ieee80211_ht_cap) +
                   2 + sizeof(struct ieee80211_ht_operation) +
                   2 + ifmsh->mesh_id_len +
                   2 + sizeof(struct ieee80211_meshconf_ie) +
                   2 + sizeof(__le16) + /* awake window */
                   2 + sizeof(struct ieee80211_vht_cap) +
                   2 + sizeof(struct ieee80211_vht_operation) +
                   ifmsh->ie_len;

        bcn = kzalloc(sizeof(*bcn) + head_len + tail_len, GFP_KERNEL);
        /* need an skb for IE builders to operate on */
        skb = dev_alloc_skb(max(head_len, tail_len));

        if (!bcn || !skb)
                goto out_free;

        /*
         * pointers go into the block we allocated,
         * memory is | beacon_data | head | tail |
         */
        bcn->head = ((u8 *) bcn) + sizeof(*bcn);

        /* fill in the head */
        mgmt = skb_put_zero(skb, hdr_len);
        mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                                          IEEE80211_STYPE_BEACON);
        eth_broadcast_addr(mgmt->da);
        memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
        memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
        ieee80211_mps_set_frame_flags(sdata, NULL, (void *) mgmt);
        mgmt->u.beacon.beacon_int =
                cpu_to_le16(sdata->vif.bss_conf.beacon_int);
        mgmt->u.beacon.capab_info |= cpu_to_le16(
                sdata->u.mesh.security ? WLAN_CAPABILITY_PRIVACY : 0);

        pos = skb_put(skb, 2);
        *pos++ = WLAN_EID_SSID;
        *pos++ = 0x0;

        rcu_read_lock();
        csa = rcu_dereference(ifmsh->csa);
        if (csa) {
                enum nl80211_channel_type ct;
                struct cfg80211_chan_def *chandef;
                int ie_len = 2 + sizeof(struct ieee80211_channel_sw_ie) +
                             2 + sizeof(struct ieee80211_mesh_chansw_params_ie);

                pos = skb_put_zero(skb, ie_len);
                *pos++ = WLAN_EID_CHANNEL_SWITCH;
                *pos++ = 3;
                *pos++ = 0x0;
                *pos++ = ieee80211_frequency_to_channel(
                                csa->settings.chandef.chan->center_freq);
                bcn->csa_current_counter = csa->settings.count;
                bcn->csa_counter_offsets[0] = hdr_len + 6;
                *pos++ = csa->settings.count;
                *pos++ = WLAN_EID_CHAN_SWITCH_PARAM;
                *pos++ = 6;
                if (ifmsh->csa_role == IEEE80211_MESH_CSA_ROLE_INIT) {
                        *pos++ = ifmsh->mshcfg.dot11MeshTTL;
                        *pos |= WLAN_EID_CHAN_SWITCH_PARAM_INITIATOR;
                } else {
                        *pos++ = ifmsh->chsw_ttl;
                }
                *pos++ |= csa->settings.block_tx ?
                          WLAN_EID_CHAN_SWITCH_PARAM_TX_RESTRICT : 0x00;
                put_unaligned_le16(WLAN_REASON_MESH_CHAN, pos);
                pos += 2;
                put_unaligned_le16(ifmsh->pre_value, pos);
                pos += 2;

                switch (csa->settings.chandef.width) {
                case NL80211_CHAN_WIDTH_40:
                        ie_len = 2 + sizeof(struct ieee80211_sec_chan_offs_ie);
                        pos = skb_put_zero(skb, ie_len);

                        *pos++ = WLAN_EID_SECONDARY_CHANNEL_OFFSET; /* EID */
                        *pos++ = 1;                                 /* len */
                        ct = cfg80211_get_chandef_type(&csa->settings.chandef);
                        if (ct == NL80211_CHAN_HT40PLUS)
                                *pos++ = IEEE80211_HT_PARAM_CHA_SEC_ABOVE;
                        else
                                *pos++ = IEEE80211_HT_PARAM_CHA_SEC_BELOW;
                        break;
                case NL80211_CHAN_WIDTH_80:
                case NL80211_CHAN_WIDTH_80P80:
                case NL80211_CHAN_WIDTH_160:
                        /* Channel Switch Wrapper + Wide Bandwidth CSA IE */
                        ie_len = 2 + 2 +
                                 sizeof(struct ieee80211_wide_bw_chansw_ie);
                        pos = skb_put_zero(skb, ie_len);

                        *pos++ = WLAN_EID_CHANNEL_SWITCH_WRAPPER; /* EID */
                        *pos++ = 5;                               /* len */
                        /* put sub IE */
                        chandef = &csa->settings.chandef;
                        ieee80211_ie_build_wide_bw_cs(pos, chandef);
                        break;
                default:
                        break;
                }
        }
        rcu_read_unlock();

        if (ieee80211_add_srates_ie(sdata, skb, true, band) ||
            mesh_add_ds_params_ie(sdata, skb))
                goto out_free;

        bcn->head_len = skb->len;
        memcpy(bcn->head, skb->data, bcn->head_len);

        /* now the tail */
        skb_trim(skb, 0);
        bcn->tail = bcn->head + bcn->head_len;

        if (ieee80211_add_ext_srates_ie(sdata, skb, true, band) ||
            mesh_add_rsn_ie(sdata, skb) ||
            mesh_add_ht_cap_ie(sdata, skb) ||
            mesh_add_ht_oper_ie(sdata, skb) ||
            mesh_add_meshid_ie(sdata, skb) ||
            mesh_add_meshconf_ie(sdata, skb) ||
            mesh_add_awake_window_ie(sdata, skb) ||
            mesh_add_vht_cap_ie(sdata, skb) ||
            mesh_add_vht_oper_ie(sdata, skb) ||
            mesh_add_vendor_ies(sdata, skb))
                goto out_free;

        bcn->tail_len = skb->len;
        memcpy(bcn->tail, skb->data, bcn->tail_len);
        bcn->meshconf = (struct ieee80211_meshconf_ie *)
                                        (bcn->tail + ifmsh->meshconf_offset);

        dev_kfree_skb(skb);
        rcu_assign_pointer(ifmsh->beacon, bcn);
        return 0;
out_free:
        kfree(bcn);
        dev_kfree_skb(skb);
        return -ENOMEM;
}

static int
ieee80211_mesh_rebuild_beacon(struct ieee80211_sub_if_data *sdata)
{
        struct beacon_data *old_bcn;
        int ret;

        old_bcn = rcu_dereference_protected(sdata->u.mesh.beacon,
                                            lockdep_is_held(&sdata->wdev.mtx));
        ret = ieee80211_mesh_build_beacon(&sdata->u.mesh);
        if (ret)
                /* just reuse old beacon */
                return ret;

        if (old_bcn)
                kfree_rcu(old_bcn, rcu_head);
        return 0;
}

void ieee80211_mbss_info_change_notify(struct ieee80211_sub_if_data *sdata,
                                       u32 changed)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        unsigned long bits = changed;
        u32 bit;

        if (!bits)
                return;

        /* if we race with running work, worst case this work becomes a noop */
        for_each_set_bit(bit, &bits, sizeof(changed) * BITS_PER_BYTE)
                set_bit(bit, &ifmsh->mbss_changed);
        set_bit(MESH_WORK_MBSS_CHANGED, &ifmsh->wrkq_flags);
        ieee80211_queue_work(&sdata->local->hw, &sdata->work);
}

int ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        struct ieee80211_local *local = sdata->local;
        u32 changed = BSS_CHANGED_BEACON |
                      BSS_CHANGED_BEACON_ENABLED |
                      BSS_CHANGED_HT |
                      BSS_CHANGED_BASIC_RATES |
                      BSS_CHANGED_BEACON_INT;

        local->fif_other_bss++;
        /* mesh ifaces must set allmulti to forward mcast traffic */
        atomic_inc(&local->iff_allmultis);
        ieee80211_configure_filter(local);

        ifmsh->mesh_cc_id = 0;  /* Disabled */
        /* register sync ops from extensible synchronization framework */
        ifmsh->sync_ops = ieee80211_mesh_sync_ops_get(ifmsh->mesh_sp_id);
        ifmsh->sync_offset_clockdrift_max = 0;
        set_bit(MESH_WORK_HOUSEKEEPING, &ifmsh->wrkq_flags);
        ieee80211_mesh_root_setup(ifmsh);
        ieee80211_queue_work(&local->hw, &sdata->work);
        sdata->vif.bss_conf.ht_operation_mode =
                                ifmsh->mshcfg.ht_opmode;
        sdata->vif.bss_conf.enable_beacon = true;

        changed |= ieee80211_mps_local_status_update(sdata);

        if (ieee80211_mesh_build_beacon(ifmsh)) {
                ieee80211_stop_mesh(sdata);
                return -ENOMEM;
        }

        ieee80211_recalc_dtim(local, sdata);
        ieee80211_bss_info_change_notify(sdata, changed);

        netif_carrier_on(sdata->dev);
        return 0;
}

void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        struct beacon_data *bcn;

        netif_carrier_off(sdata->dev);

        /* flush STAs and mpaths on this iface */
        sta_info_flush(sdata);
        mesh_path_flush_by_iface(sdata);

        /* stop the beacon */
        ifmsh->mesh_id_len = 0;
        sdata->vif.bss_conf.enable_beacon = false;
        clear_bit(SDATA_STATE_OFFCHANNEL_BEACON_STOPPED, &sdata->state);
        ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED);

        /* remove beacon */
        bcn = rcu_dereference_protected(ifmsh->beacon,
                                        lockdep_is_held(&sdata->wdev.mtx));
        RCU_INIT_POINTER(ifmsh->beacon, NULL);
        kfree_rcu(bcn, rcu_head);

        /* free all potentially still buffered group-addressed frames */
        local->total_ps_buffered -= skb_queue_len(&ifmsh->ps.bc_buf);
        skb_queue_purge(&ifmsh->ps.bc_buf);

        del_timer_sync(&sdata->u.mesh.housekeeping_timer);
        del_timer_sync(&sdata->u.mesh.mesh_path_root_timer);
        del_timer_sync(&sdata->u.mesh.mesh_path_timer);

        /* clear any mesh work (for next join) we may have accrued */
        ifmsh->wrkq_flags = 0;
        ifmsh->mbss_changed = 0;

        local->fif_other_bss--;
        atomic_dec(&local->iff_allmultis);
        ieee80211_configure_filter(local);
}

static void ieee80211_mesh_csa_mark_radar(struct ieee80211_sub_if_data *sdata)
{
        int err;

        /* if the current channel is a DFS channel, mark the channel as
         * unavailable.
         */
        err = cfg80211_chandef_dfs_required(sdata->local->hw.wiphy,
                                            &sdata->vif.bss_conf.chandef,
                                            NL80211_IFTYPE_MESH_POINT);
        if (err > 0)
                cfg80211_radar_event(sdata->local->hw.wiphy,
                                     &sdata->vif.bss_conf.chandef, GFP_ATOMIC);
}

static bool
ieee80211_mesh_process_chnswitch(struct ieee80211_sub_if_data *sdata,
                                 struct ieee802_11_elems *elems, bool beacon)
{
        struct cfg80211_csa_settings params;
        struct ieee80211_csa_ie csa_ie;
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        struct ieee80211_supported_band *sband;
        int err;
        u32 sta_flags;

        sdata_assert_lock(sdata);

        sband = ieee80211_get_sband(sdata);
        if (!sband)
                return false;

        sta_flags = 0;
        switch (sdata->vif.bss_conf.chandef.width) {
        case NL80211_CHAN_WIDTH_20_NOHT:
                sta_flags |= IEEE80211_STA_DISABLE_HT;
        case NL80211_CHAN_WIDTH_20:
                sta_flags |= IEEE80211_STA_DISABLE_40MHZ;
        case NL80211_CHAN_WIDTH_40:
                sta_flags |= IEEE80211_STA_DISABLE_VHT;
                break;
        default:
                break;
        }

        memset(&params, 0, sizeof(params));
        err = ieee80211_parse_ch_switch_ie(sdata, elems, sband->band,
                                           sta_flags, sdata->vif.addr,
                                           &csa_ie);
        if (err < 0)
                return false;
        if (err)
                return false;

        /* Mark the channel unavailable if the reason for the switch is
         * regulatory.
         */
        if (csa_ie.reason_code == WLAN_REASON_MESH_CHAN_REGULATORY)
                ieee80211_mesh_csa_mark_radar(sdata);

        params.chandef = csa_ie.chandef;
        params.count = csa_ie.count;

        if (!cfg80211_chandef_usable(sdata->local->hw.wiphy, &params.chandef,
                                     IEEE80211_CHAN_DISABLED) ||
            !cfg80211_reg_can_beacon(sdata->local->hw.wiphy, &params.chandef,
                                     NL80211_IFTYPE_MESH_POINT)) {
                sdata_info(sdata,
                           "mesh STA %pM switches to unsupported channel (%d MHz, width:%d, CF1/2: %d/%d MHz), aborting\n",
                           sdata->vif.addr,
                           params.chandef.chan->center_freq,
                           params.chandef.width,
                           params.chandef.center_freq1,
                           params.chandef.center_freq2);
                return false;
        }

        err = cfg80211_chandef_dfs_required(sdata->local->hw.wiphy,
                                            &params.chandef,
                                            NL80211_IFTYPE_MESH_POINT);
        if (err < 0)
                return false;
        if (err > 0 && !ifmsh->userspace_handles_dfs) {
                sdata_info(sdata,
                           "mesh STA %pM switches to channel requiring DFS (%d MHz, width:%d, CF1/2: %d/%d MHz), aborting\n",
                           sdata->vif.addr,
                           params.chandef.chan->center_freq,
                           params.chandef.width,
                           params.chandef.center_freq1,
                           params.chandef.center_freq2);
                return false;
        }

        params.radar_required = err;

        if (cfg80211_chandef_identical(&params.chandef,
                                       &sdata->vif.bss_conf.chandef)) {
                mcsa_dbg(sdata,
                         "received csa with an identical chandef, ignoring\n");
                return true;
        }

        mcsa_dbg(sdata,
                 "received channel switch announcement to go to channel %d MHz\n",
                 params.chandef.chan->center_freq);

        params.block_tx = csa_ie.mode & WLAN_EID_CHAN_SWITCH_PARAM_TX_RESTRICT;
        if (beacon) {
                ifmsh->chsw_ttl = csa_ie.ttl - 1;
                if (ifmsh->pre_value >= csa_ie.pre_value)
                        return false;
                ifmsh->pre_value = csa_ie.pre_value;
        }

        if (ifmsh->chsw_ttl >= ifmsh->mshcfg.dot11MeshTTL)
                return false;

        ifmsh->csa_role = IEEE80211_MESH_CSA_ROLE_REPEATER;

        if (ieee80211_channel_switch(sdata->local->hw.wiphy, sdata->dev,
                                     &params) < 0)
                return false;

        return true;
}

static void
ieee80211_mesh_rx_probe_req(struct ieee80211_sub_if_data *sdata,
                            struct ieee80211_mgmt *mgmt, size_t len)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        struct sk_buff *presp;
        struct beacon_data *bcn;
        struct ieee80211_mgmt *hdr;
        struct ieee802_11_elems elems;
        size_t baselen;
        u8 *pos;

        pos = mgmt->u.probe_req.variable;
        baselen = (u8 *) pos - (u8 *) mgmt;
        if (baselen > len)
                return;

        ieee802_11_parse_elems(pos, len - baselen, false, &elems);

        if (!elems.mesh_id)
                return;

        /* 802.11-2012 10.1.4.3.2 */
        if ((!ether_addr_equal(mgmt->da, sdata->vif.addr) &&
             !is_broadcast_ether_addr(mgmt->da)) ||
            elems.ssid_len != 0)
                return;

        if (elems.mesh_id_len != 0 &&
            (elems.mesh_id_len != ifmsh->mesh_id_len ||
             memcmp(elems.mesh_id, ifmsh->mesh_id, ifmsh->mesh_id_len)))
                return;

        rcu_read_lock();
        bcn = rcu_dereference(ifmsh->beacon);

        if (!bcn)
                goto out;

        presp = dev_alloc_skb(local->tx_headroom +
                              bcn->head_len + bcn->tail_len);
        if (!presp)
                goto out;

        skb_reserve(presp, local->tx_headroom);
        skb_put_data(presp, bcn->head, bcn->head_len);
        skb_put_data(presp, bcn->tail, bcn->tail_len);
        hdr = (struct ieee80211_mgmt *) presp->data;
        hdr->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                                         IEEE80211_STYPE_PROBE_RESP);
        memcpy(hdr->da, mgmt->sa, ETH_ALEN);
        IEEE80211_SKB_CB(presp)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT;
        ieee80211_tx_skb(sdata, presp);
out:
        rcu_read_unlock();
}

static void ieee80211_mesh_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
                                        u16 stype,
                                        struct ieee80211_mgmt *mgmt,
                                        size_t len,
                                        struct ieee80211_rx_status *rx_status)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        struct ieee802_11_elems elems;
        struct ieee80211_channel *channel;
        size_t baselen;
        int freq;
        enum nl80211_band band = rx_status->band;

        /* ignore ProbeResp to foreign address */
        if (stype == IEEE80211_STYPE_PROBE_RESP &&
            !ether_addr_equal(mgmt->da, sdata->vif.addr))
                return;

        baselen = (u8 *) mgmt->u.probe_resp.variable - (u8 *) mgmt;
        if (baselen > len)
                return;

        ieee802_11_parse_elems(mgmt->u.probe_resp.variable, len - baselen,
                               false, &elems);

        /* ignore non-mesh or secure / unsecure mismatch */
        if ((!elems.mesh_id || !elems.mesh_config) ||
            (elems.rsn && sdata->u.mesh.security == IEEE80211_MESH_SEC_NONE) ||
            (!elems.rsn && sdata->u.mesh.security != IEEE80211_MESH_SEC_NONE))
                return;

        if (elems.ds_params)
                freq = ieee80211_channel_to_frequency(elems.ds_params[0], band);
        else
                freq = rx_status->freq;

        channel = ieee80211_get_channel(local->hw.wiphy, freq);

        if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
                return;

        if (mesh_matches_local(sdata, &elems)) {
                mpl_dbg(sdata, "rssi_threshold=%d,rx_status->signal=%d\n",
                        sdata->u.mesh.mshcfg.rssi_threshold, rx_status->signal);
                if (!sdata->u.mesh.user_mpm ||
                    sdata->u.mesh.mshcfg.rssi_threshold == 0 ||
                    sdata->u.mesh.mshcfg.rssi_threshold < rx_status->signal)
                        mesh_neighbour_update(sdata, mgmt->sa, &elems);
        }

        if (ifmsh->sync_ops)
                ifmsh->sync_ops->rx_bcn_presp(sdata,
                        stype, mgmt, &elems, rx_status);

        if (ifmsh->csa_role != IEEE80211_MESH_CSA_ROLE_INIT &&
            !sdata->vif.csa_active)
                ieee80211_mesh_process_chnswitch(sdata, &elems, true);
}

int ieee80211_mesh_finish_csa(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        struct mesh_csa_settings *tmp_csa_settings;
        int ret = 0;
        int changed = 0;

        /* Reset the TTL value and Initiator flag */
        ifmsh->csa_role = IEEE80211_MESH_CSA_ROLE_NONE;
        ifmsh->chsw_ttl = 0;

        /* Remove the CSA and MCSP elements from the beacon */
        tmp_csa_settings = rcu_dereference(ifmsh->csa);
        RCU_INIT_POINTER(ifmsh->csa, NULL);
        if (tmp_csa_settings)
                kfree_rcu(tmp_csa_settings, rcu_head);
        ret = ieee80211_mesh_rebuild_beacon(sdata);
        if (ret)
                return -EINVAL;

        changed |= BSS_CHANGED_BEACON;

        mcsa_dbg(sdata, "complete switching to center freq %d MHz",
                 sdata->vif.bss_conf.chandef.chan->center_freq);
        return changed;
}

int ieee80211_mesh_csa_beacon(struct ieee80211_sub_if_data *sdata,
                              struct cfg80211_csa_settings *csa_settings)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        struct mesh_csa_settings *tmp_csa_settings;
        int ret = 0;

        tmp_csa_settings = kmalloc(sizeof(*tmp_csa_settings),
                                   GFP_ATOMIC);
        if (!tmp_csa_settings)
                return -ENOMEM;

        memcpy(&tmp_csa_settings->settings, csa_settings,
               sizeof(struct cfg80211_csa_settings));

        rcu_assign_pointer(ifmsh->csa, tmp_csa_settings);

        ret = ieee80211_mesh_rebuild_beacon(sdata);
        if (ret) {
                tmp_csa_settings = rcu_dereference(ifmsh->csa);
                RCU_INIT_POINTER(ifmsh->csa, NULL);
                kfree_rcu(tmp_csa_settings, rcu_head);
                return ret;
        }

        return BSS_CHANGED_BEACON;
}

static int mesh_fwd_csa_frame(struct ieee80211_sub_if_data *sdata,
                               struct ieee80211_mgmt *mgmt, size_t len)
{
        struct ieee80211_mgmt *mgmt_fwd;
        struct sk_buff *skb;
        struct ieee80211_local *local = sdata->local;
        u8 *pos = mgmt->u.action.u.chan_switch.variable;
        size_t offset_ttl;

        skb = dev_alloc_skb(local->tx_headroom + len);
        if (!skb)
                return -ENOMEM;
        skb_reserve(skb, local->tx_headroom);
        mgmt_fwd = skb_put(skb, len);

        /* offset_ttl is based on whether the secondary channel
         * offset is available or not. Subtract 1 from the mesh TTL
         * and disable the initiator flag before forwarding.
         */
        offset_ttl = (len < 42) ? 7 : 10;
        *(pos + offset_ttl) -= 1;
        *(pos + offset_ttl + 1) &= ~WLAN_EID_CHAN_SWITCH_PARAM_INITIATOR;

        memcpy(mgmt_fwd, mgmt, len);
        eth_broadcast_addr(mgmt_fwd->da);
        memcpy(mgmt_fwd->sa, sdata->vif.addr, ETH_ALEN);
        memcpy(mgmt_fwd->bssid, sdata->vif.addr, ETH_ALEN);

        ieee80211_tx_skb(sdata, skb);
        return 0;
}

static void mesh_rx_csa_frame(struct ieee80211_sub_if_data *sdata,
                              struct ieee80211_mgmt *mgmt, size_t len)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        struct ieee802_11_elems elems;
        u16 pre_value;
        bool fwd_csa = true;
        size_t baselen;
        u8 *pos;

        if (mgmt->u.action.u.measurement.action_code !=
            WLAN_ACTION_SPCT_CHL_SWITCH)
                return;

        pos = mgmt->u.action.u.chan_switch.variable;
        baselen = offsetof(struct ieee80211_mgmt,
                           u.action.u.chan_switch.variable);
        ieee802_11_parse_elems(pos, len - baselen, true, &elems);

        ifmsh->chsw_ttl = elems.mesh_chansw_params_ie->mesh_ttl;
        if (!--ifmsh->chsw_ttl)
                fwd_csa = false;

        pre_value = le16_to_cpu(elems.mesh_chansw_params_ie->mesh_pre_value);
        if (ifmsh->pre_value >= pre_value)
                return;

        ifmsh->pre_value = pre_value;

        if (!sdata->vif.csa_active &&
            !ieee80211_mesh_process_chnswitch(sdata, &elems, false)) {
                mcsa_dbg(sdata, "Failed to process CSA action frame");
                return;
        }

        /* forward or re-broadcast the CSA frame */
        if (fwd_csa) {
                if (mesh_fwd_csa_frame(sdata, mgmt, len) < 0)
                        mcsa_dbg(sdata, "Failed to forward the CSA frame");
        }
}

static void ieee80211_mesh_rx_mgmt_action(struct ieee80211_sub_if_data *sdata,
                                          struct ieee80211_mgmt *mgmt,
                                          size_t len,
                                          struct ieee80211_rx_status *rx_status)
{
        switch (mgmt->u.action.category) {
        case WLAN_CATEGORY_SELF_PROTECTED:
                switch (mgmt->u.action.u.self_prot.action_code) {
                case WLAN_SP_MESH_PEERING_OPEN:
                case WLAN_SP_MESH_PEERING_CLOSE:
                case WLAN_SP_MESH_PEERING_CONFIRM:
                        mesh_rx_plink_frame(sdata, mgmt, len, rx_status);
                        break;
                }
                break;
        case WLAN_CATEGORY_MESH_ACTION:
                if (mesh_action_is_path_sel(mgmt))
                        mesh_rx_path_sel_frame(sdata, mgmt, len);
                break;
        case WLAN_CATEGORY_SPECTRUM_MGMT:
                mesh_rx_csa_frame(sdata, mgmt, len);
                break;
        }
}

void ieee80211_mesh_rx_queued_mgmt(struct ieee80211_sub_if_data *sdata,
                                   struct sk_buff *skb)
{
        struct ieee80211_rx_status *rx_status;
        struct ieee80211_mgmt *mgmt;
        u16 stype;

        sdata_lock(sdata);

        /* mesh already went down */
        if (!sdata->u.mesh.mesh_id_len)
                goto out;

        rx_status = IEEE80211_SKB_RXCB(skb);
        mgmt = (struct ieee80211_mgmt *) skb->data;
        stype = le16_to_cpu(mgmt->frame_control) & IEEE80211_FCTL_STYPE;

        switch (stype) {
        case IEEE80211_STYPE_PROBE_RESP:
        case IEEE80211_STYPE_BEACON:
                ieee80211_mesh_rx_bcn_presp(sdata, stype, mgmt, skb->len,
                                            rx_status);
                break;
        case IEEE80211_STYPE_PROBE_REQ:
                ieee80211_mesh_rx_probe_req(sdata, mgmt, skb->len);
                break;
        case IEEE80211_STYPE_ACTION:
                ieee80211_mesh_rx_mgmt_action(sdata, mgmt, skb->len, rx_status);
                break;
        }
out:
        sdata_unlock(sdata);
}

static void mesh_bss_info_changed(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        u32 bit, changed = 0;

        for_each_set_bit(bit, &ifmsh->mbss_changed,
                         sizeof(changed) * BITS_PER_BYTE) {
                clear_bit(bit, &ifmsh->mbss_changed);
                changed |= BIT(bit);
        }

        if (sdata->vif.bss_conf.enable_beacon &&
            (changed & (BSS_CHANGED_BEACON |
                        BSS_CHANGED_HT |
                        BSS_CHANGED_BASIC_RATES |
                        BSS_CHANGED_BEACON_INT)))
                if (ieee80211_mesh_rebuild_beacon(sdata))
                        return;

        ieee80211_bss_info_change_notify(sdata, changed);
}

void ieee80211_mesh_work(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;

        sdata_lock(sdata);

        /* mesh already went down */
        if (!sdata->u.mesh.mesh_id_len)
                goto out;

        if (ifmsh->preq_queue_len &&
            time_after(jiffies,
                       ifmsh->last_preq + msecs_to_jiffies(ifmsh->mshcfg.dot11MeshHWMPpreqMinInterval)))
                mesh_path_start_discovery(sdata);

        if (test_and_clear_bit(MESH_WORK_HOUSEKEEPING, &ifmsh->wrkq_flags))
                ieee80211_mesh_housekeeping(sdata);

        if (test_and_clear_bit(MESH_WORK_ROOT, &ifmsh->wrkq_flags))
                ieee80211_mesh_rootpath(sdata);

        if (test_and_clear_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags))
                mesh_sync_adjust_tsf(sdata);

        if (test_and_clear_bit(MESH_WORK_MBSS_CHANGED, &ifmsh->wrkq_flags))
                mesh_bss_info_changed(sdata);
out:
        sdata_unlock(sdata);
}


void ieee80211_mesh_init_sdata(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        static u8 zero_addr[ETH_ALEN] = {};

        setup_timer(&ifmsh->housekeeping_timer,
                    ieee80211_mesh_housekeeping_timer,
                    (unsigned long) sdata);

        ifmsh->accepting_plinks = true;
        atomic_set(&ifmsh->mpaths, 0);
        mesh_rmc_init(sdata);
        ifmsh->last_preq = jiffies;
        ifmsh->next_perr = jiffies;
        ifmsh->csa_role = IEEE80211_MESH_CSA_ROLE_NONE;
        /* Allocate all mesh structures when creating the first mesh interface. */
        if (!mesh_allocated)
                ieee80211s_init();

        mesh_pathtbl_init(sdata);

        setup_timer(&ifmsh->mesh_path_timer,
                    ieee80211_mesh_path_timer,
                    (unsigned long) sdata);
        setup_timer(&ifmsh->mesh_path_root_timer,
                    ieee80211_mesh_path_root_timer,
                    (unsigned long) sdata);
        INIT_LIST_HEAD(&ifmsh->preq_queue.list);
        skb_queue_head_init(&ifmsh->ps.bc_buf);
        spin_lock_init(&ifmsh->mesh_preq_queue_lock);
        spin_lock_init(&ifmsh->sync_offset_lock);
        RCU_INIT_POINTER(ifmsh->beacon, NULL);

        sdata->vif.bss_conf.bssid = zero_addr;
}

void ieee80211_mesh_teardown_sdata(struct ieee80211_sub_if_data *sdata)
{
        mesh_rmc_free(sdata);
        mesh_pathtbl_unregister(sdata);
}