net/mac80211/offchannel.c - kernel/msm-4.9 - Gitiles

 /*
  * 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-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_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_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_del(&dep->list);
 			list_add(&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;
 	}

 	ieee80211_start_next_roc(local);
 	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));
 }
	/*
	* 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-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_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_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_del(&dep->list);
	list_add(&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;
	}

	ieee80211_start_next_roc(local);
	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));
	}