chan.c

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/*
 * mac80211 - channel management
 */

#include <linux/nl80211.h>
#include "ieee80211_i.h"

static enum ieee80211_chan_mode
__ieee80211_get_channel_mode(struct ieee80211_local *local,
                             struct ieee80211_sub_if_data *ignore)
{
        struct ieee80211_sub_if_data *sdata;

        lockdep_assert_held(&local->iflist_mtx);

        list_for_each_entry(sdata, &local->interfaces, list) {
                if (sdata == ignore)
                        continue;

                if (!ieee80211_sdata_running(sdata))
                        continue;

                if (sdata->vif.type == NL80211_IFTYPE_MONITOR)
                        continue;

                if (sdata->vif.type == NL80211_IFTYPE_STATION &&
                    !sdata->u.mgd.associated)
                        continue;

                if (sdata->vif.type == NL80211_IFTYPE_ADHOC) {
                        if (!sdata->u.ibss.ssid_len)
                                continue;
                        if (!sdata->u.ibss.fixed_channel)
                                return CHAN_MODE_HOPPING;
                }

                if (sdata->vif.type == NL80211_IFTYPE_AP &&
                    !sdata->u.ap.beacon)
                        continue;

                return CHAN_MODE_FIXED;
        }

        return CHAN_MODE_UNDEFINED;
}

enum ieee80211_chan_mode
ieee80211_get_channel_mode(struct ieee80211_local *local,
                           struct ieee80211_sub_if_data *ignore)
{
        enum ieee80211_chan_mode mode;

        mutex_lock(&local->iflist_mtx);
        mode = __ieee80211_get_channel_mode(local, ignore);
        mutex_unlock(&local->iflist_mtx);

        return mode;
}

bool ieee80211_set_channel_type(struct ieee80211_local *local,
                                struct ieee80211_sub_if_data *sdata,
                                enum nl80211_channel_type chantype)
{
        struct ieee80211_sub_if_data *tmp;
        enum nl80211_channel_type superchan = NL80211_CHAN_NO_HT;
        bool result;

        mutex_lock(&local->iflist_mtx);

        list_for_each_entry(tmp, &local->interfaces, list) {
                if (tmp == sdata)
                        continue;

                if (!ieee80211_sdata_running(tmp))
                        continue;

                switch (tmp->vif.bss_conf.channel_type) {
                case NL80211_CHAN_NO_HT:
                case NL80211_CHAN_HT20:
                        if (superchan > tmp->vif.bss_conf.channel_type)
                                break;

                        superchan = tmp->vif.bss_conf.channel_type;
                        break;
                case NL80211_CHAN_HT40PLUS:
                        WARN_ON(superchan == NL80211_CHAN_HT40MINUS);
                        superchan = NL80211_CHAN_HT40PLUS;
                        break;
                case NL80211_CHAN_HT40MINUS:
                        WARN_ON(superchan == NL80211_CHAN_HT40PLUS);
                        superchan = NL80211_CHAN_HT40MINUS;
                        break;
                }
        }

        switch (superchan) {
        case NL80211_CHAN_NO_HT:
        case NL80211_CHAN_HT20:
                /*
                 * allow any change that doesn't go to no-HT
                 * (if it already is no-HT no change is needed)
                 */
                if (chantype == NL80211_CHAN_NO_HT)
                        break;
                superchan = chantype;
                break;
        case NL80211_CHAN_HT40PLUS:
        case NL80211_CHAN_HT40MINUS:
                /* allow smaller bandwidth and same */
                if (chantype == NL80211_CHAN_NO_HT)
                        break;
                if (chantype == NL80211_CHAN_HT20)
                        break;
                if (superchan == chantype)
                        break;
                result = false;
                goto out;
        }

        local->_oper_channel_type = superchan;

        if (sdata)
                sdata->vif.bss_conf.channel_type = chantype;

        result = true;
 out:
        mutex_unlock(&local->iflist_mtx);

        return result;
}