static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
				     struct cfg80211_bss *cbss, bool assoc,
				     bool override)
{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
	struct ieee80211_bss *bss = (void *)cbss->priv;
	struct sta_info *new_sta = NULL;
	struct ieee80211_supported_band *sband;
	bool have_sta = false;
	int err;

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

	if (WARN_ON(!ifmgd->auth_data && !ifmgd->assoc_data))
		return -EINVAL;

	/* If a reconfig is happening, bail out */
	if (local->in_reconfig)
		return -EBUSY;

	if (assoc) {
		rcu_read_lock();
		have_sta = sta_info_get(sdata, cbss->bssid);
		rcu_read_unlock();
	}

	if (!have_sta) {
		new_sta = sta_info_alloc(sdata, cbss->bssid, GFP_KERNEL);
		if (!new_sta)
			return -ENOMEM;
	}

	/*
	 * Set up the information for the new channel before setting the
	 * new channel. We can't - completely race-free - change the basic
	 * rates bitmap and the channel (sband) that it refers to, but if
	 * we set it up before we at least avoid calling into the driver's
	 * bss_info_changed() method with invalid information (since we do
	 * call that from changing the channel - only for IDLE and perhaps
	 * some others, but ...).
	 *
	 * So to avoid that, just set up all the new information before the
	 * channel, but tell the driver to apply it only afterwards, since
	 * it might need the new channel for that.
	 */
	if (new_sta) {
		u32 rates = 0, basic_rates = 0;
		bool have_higher_than_11mbit;
		int min_rate = INT_MAX, min_rate_index = -1;
		const struct cfg80211_bss_ies *ies;
		int shift = ieee80211_vif_get_shift(&sdata->vif);

		ieee80211_get_rates(sband, bss->supp_rates,
				    bss->supp_rates_len,
				    &rates, &basic_rates,
				    &have_higher_than_11mbit,
				    &min_rate, &min_rate_index,
				    shift);

		/*
		 * This used to be a workaround for basic rates missing
		 * in the association response frame. Now that we no
		 * longer use the basic rates from there, it probably
		 * doesn't happen any more, but keep the workaround so
		 * in case some *other* APs are buggy in different ways
		 * we can connect -- with a warning.
		 */
		if (!basic_rates && min_rate_index >= 0) {
			sdata_info(sdata,
				   "No basic rates, using min rate instead\n");
			basic_rates = BIT(min_rate_index);
		}

		new_sta->sta.supp_rates[cbss->channel->band] = rates;
		sdata->vif.bss_conf.basic_rates = basic_rates;

		/* cf. IEEE 802.11 9.2.12 */
		if (cbss->channel->band == NL80211_BAND_2GHZ &&
		    have_higher_than_11mbit)
			sdata->flags |= IEEE80211_SDATA_OPERATING_GMODE;
		else
			sdata->flags &= ~IEEE80211_SDATA_OPERATING_GMODE;

		memcpy(ifmgd->bssid, cbss->bssid, ETH_ALEN);

		/* set timing information */
		sdata->vif.bss_conf.beacon_int = cbss->beacon_interval;
		rcu_read_lock();
		ies = rcu_dereference(cbss->beacon_ies);
		if (ies) {
			sdata->vif.bss_conf.sync_tsf = ies->tsf;
			sdata->vif.bss_conf.sync_device_ts =
				bss->device_ts_beacon;

			ieee80211_get_dtim(ies,
					   &sdata->vif.bss_conf.sync_dtim_count,
					   NULL);
		} else if (!ieee80211_hw_check(&sdata->local->hw,
					       TIMING_BEACON_ONLY)) {
			ies = rcu_dereference(cbss->proberesp_ies);
			/* must be non-NULL since beacon IEs were NULL */
			sdata->vif.bss_conf.sync_tsf = ies->tsf;
			sdata->vif.bss_conf.sync_device_ts =
				bss->device_ts_presp;
			sdata->vif.bss_conf.sync_dtim_count = 0;
		} else {
			sdata->vif.bss_conf.sync_tsf = 0;
			sdata->vif.bss_conf.sync_device_ts = 0;
			sdata->vif.bss_conf.sync_dtim_count = 0;
		}
		rcu_read_unlock();
	}

	if (new_sta || override) {
		err = ieee80211_prep_channel(sdata, cbss);
		if (err) {
			if (new_sta)
				sta_info_free(local, new_sta);
			return -EINVAL;
		}
	}

	if (new_sta) {
		/*
		 * tell driver about BSSID, basic rates and timing
		 * this was set up above, before setting the channel
		 */
		ieee80211_bss_info_change_notify(sdata,
			BSS_CHANGED_BSSID | BSS_CHANGED_BASIC_RATES |
			BSS_CHANGED_BEACON_INT);

		if (assoc)
			sta_info_pre_move_state(new_sta, IEEE80211_STA_AUTH);

		err = sta_info_insert(new_sta);
		new_sta = NULL;
		if (err) {
			sdata_info(sdata,
				   "failed to insert STA entry for the AP (error %d)\n",
				   err);
			return err;
		}
	} else
		WARN_ON_ONCE(!ether_addr_equal(ifmgd->bssid, cbss->bssid));

	/* Cancel scan to ensure that nothing interferes with connection */
	if (local->scanning)
		ieee80211_scan_cancel(local);

	return 0;
}
static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
				     struct cfg80211_bss *cbss, bool assoc,
				     bool override)
{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
	struct ieee80211_bss *bss = (void *)cbss->priv;
	struct sta_info *new_sta = NULL;
	struct ieee80211_supported_band *sband;
	bool have_sta = false;
	int err;

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

	if (WARN_ON(!ifmgd->auth_data && !ifmgd->assoc_data))
		return -EINVAL;

	 
	if (local->in_reconfig)
		return -EBUSY;

	if (assoc) {
		rcu_read_lock();
		have_sta = sta_info_get(sdata, cbss->bssid);
		rcu_read_unlock();
	}

	if (!have_sta) {
		new_sta = sta_info_alloc(sdata, cbss->bssid, GFP_KERNEL);
		if (!new_sta)
			return -ENOMEM;
	}

	 
	if (new_sta) {
		u32 rates = 0, basic_rates = 0;
		bool have_higher_than_11mbit;
		int min_rate = INT_MAX, min_rate_index = -1;
		const struct cfg80211_bss_ies *ies;
		int shift = ieee80211_vif_get_shift(&sdata->vif);

		ieee80211_get_rates(sband, bss->supp_rates,
				    bss->supp_rates_len,
				    &rates, &basic_rates,
				    &have_higher_than_11mbit,
				    &min_rate, &min_rate_index,
				    shift);

		 
		if (!basic_rates && min_rate_index >= 0) {
			sdata_info(sdata,
				   "No basic rates, using min rate instead\n");
			basic_rates = BIT(min_rate_index);
		}

		new_sta->sta.supp_rates[cbss->channel->band] = rates;
		sdata->vif.bss_conf.basic_rates = basic_rates;

		 
		if (cbss->channel->band == NL80211_BAND_2GHZ &&
		    have_higher_than_11mbit)
			sdata->flags |= IEEE80211_SDATA_OPERATING_GMODE;
		else
			sdata->flags &= ~IEEE80211_SDATA_OPERATING_GMODE;

		memcpy(ifmgd->bssid, cbss->bssid, ETH_ALEN);

		 
		sdata->vif.bss_conf.beacon_int = cbss->beacon_interval;
		rcu_read_lock();
		ies = rcu_dereference(cbss->beacon_ies);
		if (ies) {
			sdata->vif.bss_conf.sync_tsf = ies->tsf;
			sdata->vif.bss_conf.sync_device_ts =
				bss->device_ts_beacon;

			ieee80211_get_dtim(ies,
					   &sdata->vif.bss_conf.sync_dtim_count,
					   NULL);
		} else if (!ieee80211_hw_check(&sdata->local->hw,
					       TIMING_BEACON_ONLY)) {
			ies = rcu_dereference(cbss->proberesp_ies);
			 
			sdata->vif.bss_conf.sync_tsf = ies->tsf;
			sdata->vif.bss_conf.sync_device_ts =
				bss->device_ts_presp;
			sdata->vif.bss_conf.sync_dtim_count = 0;
		} else {
			sdata->vif.bss_conf.sync_tsf = 0;
			sdata->vif.bss_conf.sync_device_ts = 0;
			sdata->vif.bss_conf.sync_dtim_count = 0;
		}
		rcu_read_unlock();
	}

	if (new_sta || override) {
		err = ieee80211_prep_channel(sdata, cbss);
		if (err) {
			if (new_sta)
				sta_info_free(local, new_sta);
			return -EINVAL;
		}
	}

	if (new_sta) {
		 
		ieee80211_bss_info_change_notify(sdata,
			BSS_CHANGED_BSSID | BSS_CHANGED_BASIC_RATES |
			BSS_CHANGED_BEACON_INT);

		if (assoc)
			sta_info_pre_move_state(new_sta, IEEE80211_STA_AUTH);

		err = sta_info_insert(new_sta);
		new_sta = NULL;
		if (err) {
			sdata_info(sdata,
				   "failed to insert STA entry for the AP (error %d)\n",
				   err);
			return err;
		}
	} else
		WARN_ON_ONCE(!ether_addr_equal(ifmgd->bssid, cbss->bssid));

	 
	if (local->scanning)
		ieee80211_scan_cancel(local);

	return 0;
}