offchannel.c

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/*
 * Off-channel operation helpers
 *
 * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
 * Copyright 2004, Instant802 Networks, Inc.
 * Copyright 2005, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
 * Copyright 2009       Johannes Berg <johannes@sipsolutions.net>
 *
 * 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/export.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "driver-trace.h"

/*
 * Tell our hardware to disable PS.
 * Optionally inform AP that we will go to sleep so that it will buffer
 * the frames while we are doing off-channel work.  This is optional
 * because we *may* be doing work on-operating channel, and want our
 * hardware unconditionally awake, but still let the AP send us normal frames.
 */
static void ieee80211_offchannel_ps_enable(struct ieee80211_sub_if_data *sdata,
                                           bool tell_ap)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;

        local->offchannel_ps_enabled = false;

        /* FIXME: what to do when local->pspolling is true? */

        del_timer_sync(&local->dynamic_ps_timer);
        del_timer_sync(&ifmgd->bcn_mon_timer);
        del_timer_sync(&ifmgd->conn_mon_timer);

        cancel_work_sync(&local->dynamic_ps_enable_work);

        if (local->hw.conf.flags & IEEE80211_CONF_PS) {
                local->offchannel_ps_enabled = true;
                local->hw.conf.flags &= ~IEEE80211_CONF_PS;
                ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
        }

        if (tell_ap && (!local->offchannel_ps_enabled ||
                        !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)))
                /*
                 * If power save was enabled, no need to send a nullfunc
                 * frame because AP knows that we are sleeping. But if the
                 * hardware is creating the nullfunc frame for power save
                 * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
                 * enabled) and power save was enabled, the firmware just
                 * sent a null frame with power save disabled. So we need
                 * to send a new nullfunc frame to inform the AP that we
                 * are again sleeping.
                 */
                ieee80211_send_nullfunc(local, sdata, 1);
}

/* inform AP that we are awake again, unless power save is enabled */
static void ieee80211_offchannel_ps_disable(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_local *local = sdata->local;

        if (!local->ps_sdata)
                ieee80211_send_nullfunc(local, sdata, 0);
        else if (local->offchannel_ps_enabled) {
                /*
                 * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
                 * will send a nullfunc frame with the powersave bit set
                 * even though the AP already knows that we are sleeping.
                 * This could be avoided by sending a null frame with power
                 * save bit disabled before enabling the power save, but
                 * this doesn't gain anything.
                 *
                 * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
                 * to send a nullfunc frame because AP already knows that
                 * we are sleeping, let's just enable power save mode in
                 * hardware.
                 */
                /* TODO:  Only set hardware if CONF_PS changed?
                 * TODO:  Should we set offchannel_ps_enabled to false?
                 */
                local->hw.conf.flags |= IEEE80211_CONF_PS;
                ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
        } else if (local->hw.conf.dynamic_ps_timeout > 0) {
                /*
                 * If IEEE80211_CONF_PS was not set and the dynamic_ps_timer
                 * had been running before leaving the operating channel,
                 * restart the timer now and send a nullfunc frame to inform
                 * the AP that we are awake.
                 */
                ieee80211_send_nullfunc(local, sdata, 0);
                mod_timer(&local->dynamic_ps_timer, jiffies +
                          msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout));
        }

        ieee80211_sta_reset_beacon_monitor(sdata);
        ieee80211_sta_reset_conn_monitor(sdata);
}

void ieee80211_offchannel_stop_vifs(struct ieee80211_local *local,
                                    bool offchannel_ps_enable)
{
        struct ieee80211_sub_if_data *sdata;

        /*
         * notify the AP about us leaving the channel and stop all
         * STA interfaces.
         */
        mutex_lock(&local->iflist_mtx);
        list_for_each_entry(sdata, &local->interfaces, list) {
                if (!ieee80211_sdata_running(sdata))
                        continue;

                if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
                        set_bit(SDATA_STATE_OFFCHANNEL, &sdata->state);

                /* Check to see if we should disable beaconing. */
                if (sdata->vif.type == NL80211_IFTYPE_AP ||
                    sdata->vif.type == NL80211_IFTYPE_ADHOC ||
                    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
                        ieee80211_bss_info_change_notify(
                                sdata, BSS_CHANGED_BEACON_ENABLED);

                if (sdata->vif.type != NL80211_IFTYPE_MONITOR) {
                        netif_tx_stop_all_queues(sdata->dev);
                        if (offchannel_ps_enable &&
                            (sdata->vif.type == NL80211_IFTYPE_STATION) &&
                            sdata->u.mgd.associated)
                                ieee80211_offchannel_ps_enable(sdata, true);
                }
        }
        mutex_unlock(&local->iflist_mtx);
}

void ieee80211_offchannel_return(struct ieee80211_local *local,
                                 bool offchannel_ps_disable)
{
        struct ieee80211_sub_if_data *sdata;

        mutex_lock(&local->iflist_mtx);
        list_for_each_entry(sdata, &local->interfaces, list) {
                if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
                        clear_bit(SDATA_STATE_OFFCHANNEL, &sdata->state);

                if (!ieee80211_sdata_running(sdata))
                        continue;

                /* Tell AP we're back */
                if (offchannel_ps_disable &&
                    sdata->vif.type == NL80211_IFTYPE_STATION) {
                        if (sdata->u.mgd.associated)
                                ieee80211_offchannel_ps_disable(sdata);
                }

                if (sdata->vif.type != NL80211_IFTYPE_MONITOR) {
                        /*
                         * This may wake up queues even though the driver
                         * currently has them stopped. This is not very
                         * likely, since the driver won't have gotten any
                         * (or hardly any) new packets while we weren't
                         * on the right channel, and even if it happens
                         * it will at most lead to queueing up one more
                         * packet per queue in mac80211 rather than on
                         * the interface qdisc.
                         */
                        netif_tx_wake_all_queues(sdata->dev);
                }

                if (sdata->vif.type == NL80211_IFTYPE_AP ||
                    sdata->vif.type == NL80211_IFTYPE_ADHOC ||
                    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
                        ieee80211_bss_info_change_notify(
                                sdata, BSS_CHANGED_BEACON_ENABLED);
        }
        mutex_unlock(&local->iflist_mtx);
}

static void ieee80211_hw_roc_start(struct work_struct *work)
{
        struct ieee80211_local *local =
                container_of(work, struct ieee80211_local, hw_roc_start);
        struct ieee80211_sub_if_data *sdata;

        mutex_lock(&local->mtx);

        if (!local->hw_roc_channel) {
                mutex_unlock(&local->mtx);
                return;
        }

        if (local->hw_roc_skb) {
                sdata = IEEE80211_DEV_TO_SUB_IF(local->hw_roc_dev);
                ieee80211_tx_skb(sdata, local->hw_roc_skb);
                local->hw_roc_skb = NULL;
        } else {
                cfg80211_ready_on_channel(local->hw_roc_dev,
                                          local->hw_roc_cookie,
                                          local->hw_roc_channel,
                                          local->hw_roc_channel_type,
                                          local->hw_roc_duration,
                                          GFP_KERNEL);
        }

        ieee80211_recalc_idle(local);

        mutex_unlock(&local->mtx);
}

void ieee80211_ready_on_channel(struct ieee80211_hw *hw)
{
        struct ieee80211_local *local = hw_to_local(hw);

        trace_api_ready_on_channel(local);

        ieee80211_queue_work(hw, &local->hw_roc_start);
}
EXPORT_SYMBOL_GPL(ieee80211_ready_on_channel);

static void ieee80211_hw_roc_done(struct work_struct *work)
{
        struct ieee80211_local *local =
                container_of(work, struct ieee80211_local, hw_roc_done);

        mutex_lock(&local->mtx);

        if (!local->hw_roc_channel) {
                mutex_unlock(&local->mtx);
                return;
        }

        /* was never transmitted */
        if (local->hw_roc_skb) {
                u64 cookie;

                cookie = local->hw_roc_cookie ^ 2;

                cfg80211_mgmt_tx_status(local->hw_roc_dev, cookie,
                                        local->hw_roc_skb->data,
                                        local->hw_roc_skb->len, false,
                                        GFP_KERNEL);

                kfree_skb(local->hw_roc_skb);
                local->hw_roc_skb = NULL;
                local->hw_roc_skb_for_status = NULL;
        }

        if (!local->hw_roc_for_tx)
                cfg80211_remain_on_channel_expired(local->hw_roc_dev,
                                                   local->hw_roc_cookie,
                                                   local->hw_roc_channel,
                                                   local->hw_roc_channel_type,
                                                   GFP_KERNEL);

        local->hw_roc_channel = NULL;
        local->hw_roc_cookie = 0;

        ieee80211_recalc_idle(local);

        mutex_unlock(&local->mtx);
}

void ieee80211_remain_on_channel_expired(struct ieee80211_hw *hw)
{
        struct ieee80211_local *local = hw_to_local(hw);

        trace_api_remain_on_channel_expired(local);

        ieee80211_queue_work(hw, &local->hw_roc_done);
}
EXPORT_SYMBOL_GPL(ieee80211_remain_on_channel_expired);

void ieee80211_hw_roc_setup(struct ieee80211_local *local)
{
        INIT_WORK(&local->hw_roc_start, ieee80211_hw_roc_start);
        INIT_WORK(&local->hw_roc_done, ieee80211_hw_roc_done);
}