offchannel.c

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/*
 * Off-channel operation helpers
 *
 * Copyright 2003, Jouni Malinen <[email protected]>
 * Copyright 2004, Instant802 Networks, Inc.
 * Copyright 2005, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <[email protected]>
 * Copyright 2007, Michael Wu <[email protected]>
 * Copyright 2009   Johannes Berg <[email protected]>
 *
 * 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-ops.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)
{
    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 (!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_P2P_DEVICE)
            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);
        }
    }
    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_P2P_DEVICE)
            continue;

        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);
}

void ieee80211_handle_roc_started(struct ieee80211_roc_work *roc)
{
    if (roc->notified)
        return;

    if (roc->mgmt_tx_cookie) {
        if (!WARN_ON(!roc->frame)) {
            ieee80211_tx_skb(roc->sdata, roc->frame);
            roc->frame = NULL;
        }
    } else {
        cfg80211_ready_on_channel(&roc->sdata->wdev, (unsigned long)roc,
                      roc->chan, roc->chan_type,
                      roc->req_duration, GFP_KERNEL);
    }

    roc->notified = true;
}

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_roc_work *roc, *dep, *tmp;

    mutex_lock(&local->mtx);

    if (list_empty(&local->roc_list))
        goto out_unlock;

    roc = list_first_entry(&local->roc_list, struct ieee80211_roc_work,
                   list);

    if (!roc->started)
        goto out_unlock;

    roc->hw_begun = true;
    roc->hw_start_time = local->hw_roc_start_time;

    ieee80211_handle_roc_started(roc);
    list_for_each_entry_safe(dep, tmp, &roc->dependents, list) {
        ieee80211_handle_roc_started(dep);

        if (dep->duration > roc->duration) {
            u32 dur = dep->duration;
            dep->duration = dur - roc->duration;
            roc->duration = dur;
            list_move(&dep->list, &roc->list);
        }
    }
 out_unlock:
    mutex_unlock(&local->mtx);
}

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

    local->hw_roc_start_time = jiffies;

    trace_api_ready_on_channel(local);

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

void ieee80211_start_next_roc(struct ieee80211_local *local)
{
    struct ieee80211_roc_work *roc;

    lockdep_assert_held(&local->mtx);

    if (list_empty(&local->roc_list)) {
        ieee80211_run_deferred_scan(local);
        return;
    }

    roc = list_first_entry(&local->roc_list, struct ieee80211_roc_work,
                   list);

    if (WARN_ON_ONCE(roc->started))
        return;

    if (local->ops->remain_on_channel) {
        int ret, duration = roc->duration;

        /* XXX: duplicated, see ieee80211_start_roc_work() */
        if (!duration)
            duration = 10;

        ret = drv_remain_on_channel(local, roc->chan,
                        roc->chan_type,
                        duration);

        roc->started = true;

        if (ret) {
            wiphy_warn(local->hw.wiphy,
                   "failed to start next HW ROC (%d)\n", ret);
            /*
             * queue the work struct again to avoid recursion
             * when multiple failures occur
             */
            ieee80211_remain_on_channel_expired(&local->hw);
        }
    } else {
        /* delay it a bit */
        ieee80211_queue_delayed_work(&local->hw, &roc->work,
                         round_jiffies_relative(HZ/2));
    }
}

void ieee80211_roc_notify_destroy(struct ieee80211_roc_work *roc)
{
    struct ieee80211_roc_work *dep, *tmp;

    /* was never transmitted */
    if (roc->frame) {
        cfg80211_mgmt_tx_status(&roc->sdata->wdev,
                    (unsigned long)roc->frame,
                    roc->frame->data, roc->frame->len,
                    false, GFP_KERNEL);
        kfree_skb(roc->frame);
    }

    if (!roc->mgmt_tx_cookie)
        cfg80211_remain_on_channel_expired(&roc->sdata->wdev,
                           (unsigned long)roc,
                           roc->chan, roc->chan_type,
                           GFP_KERNEL);

    list_for_each_entry_safe(dep, tmp, &roc->dependents, list)
        ieee80211_roc_notify_destroy(dep);

    kfree(roc);
}

void ieee80211_sw_roc_work(struct work_struct *work)
{
    struct ieee80211_roc_work *roc =
        container_of(work, struct ieee80211_roc_work, work.work);
    struct ieee80211_sub_if_data *sdata = roc->sdata;
    struct ieee80211_local *local = sdata->local;
    bool started;

    mutex_lock(&local->mtx);

    if (roc->abort)
        goto finish;

    if (WARN_ON(list_empty(&local->roc_list)))
        goto out_unlock;

    if (WARN_ON(roc != list_first_entry(&local->roc_list,
                        struct ieee80211_roc_work,
                        list)))
        goto out_unlock;

    if (!roc->started) {
        struct ieee80211_roc_work *dep;

        /* start this ROC */

        /* switch channel etc */
        ieee80211_recalc_idle(local);

        local->tmp_channel = roc->chan;
        local->tmp_channel_type = roc->chan_type;
        ieee80211_hw_config(local, 0);

        /* tell userspace or send frame */
        ieee80211_handle_roc_started(roc);
        list_for_each_entry(dep, &roc->dependents, list)
            ieee80211_handle_roc_started(dep);

        /* if it was pure TX, just finish right away */
        if (!roc->duration)
            goto finish;

        roc->started = true;
        ieee80211_queue_delayed_work(&local->hw, &roc->work,
                         msecs_to_jiffies(roc->duration));
    } else {
        /* finish this ROC */
 finish:
        list_del(&roc->list);
        started = roc->started;
        ieee80211_roc_notify_destroy(roc);

        if (started) {
            drv_flush(local, false);

            local->tmp_channel = NULL;
            ieee80211_hw_config(local, 0);

            ieee80211_offchannel_return(local, true);
        }

        ieee80211_recalc_idle(local);

        if (started)
            ieee80211_start_next_roc(local);
    }

 out_unlock:
    mutex_unlock(&local->mtx);
}

static void ieee80211_hw_roc_done(struct work_struct *work)
{
    struct ieee80211_local *local =
        container_of(work, struct ieee80211_local, hw_roc_done);
    struct ieee80211_roc_work *roc;

    mutex_lock(&local->mtx);

    if (list_empty(&local->roc_list))
        goto out_unlock;

    roc = list_first_entry(&local->roc_list, struct ieee80211_roc_work,
                   list);

    if (!roc->started)
        goto out_unlock;

    list_del(&roc->list);

    ieee80211_roc_notify_destroy(roc);

    /* if there's another roc, start it now */
    ieee80211_start_next_roc(local);

 out_unlock:
    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_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);
    INIT_LIST_HEAD(&local->roc_list);
}

void ieee80211_roc_purge(struct ieee80211_sub_if_data *sdata)
{
    struct ieee80211_local *local = sdata->local;
    struct ieee80211_roc_work *roc, *tmp;
    LIST_HEAD(tmp_list);

    mutex_lock(&local->mtx);
    list_for_each_entry_safe(roc, tmp, &local->roc_list, list) {
        if (roc->sdata != sdata)
            continue;

        if (roc->started && local->ops->remain_on_channel) {
            /* can race, so ignore return value */
            drv_cancel_remain_on_channel(local);
        }

        list_move_tail(&roc->list, &tmp_list);
        roc->abort = true;
    }
    mutex_unlock(&local->mtx);

    list_for_each_entry_safe(roc, tmp, &tmp_list, list) {
        if (local->ops->remain_on_channel) {
            list_del(&roc->list);
            ieee80211_roc_notify_destroy(roc);
        } else {
            ieee80211_queue_delayed_work(&local->hw, &roc->work, 0);

            /* work will clean up etc */
            flush_delayed_work(&roc->work);
        }
    }

    WARN_ON_ONCE(!list_empty(&tmp_list));
}