diff mbox

[PATCHv3,4/5] mac80211: add channel switch command and beacon callbacks

Message ID 1373289250-12259-5-git-send-email-siwu@hrz.tu-chemnitz.de (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Simon Wunderlich July 8, 2013, 1:14 p.m. UTC
The count field in CSA must be decremented with each beacon
transmitted. This patch implements the functionality for drivers
using ieee80211_beacon_get(). Other drivers must call back manually
after reaching count == 0.

This patch also contains the handling and finish worker for the channel
switch command.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
---
Changes to PATCHv2:
 * fix documentation and style stuff
 * update tracing
 * change csa_active to bool
 * check if csa_active when assigning beacons
 * fix locking and access
 * use new ieee80211_vif_change_channel to change the channel

Changes to PATCHv1:
 * don't switch when CAC is active
 * add hw to parameters for driver

Changes to RFCv1:
 * use beacons as supplied from nl80211 without generating/parsing them
 * update beacons using offsets
 * report back by calling the channel switch event in cfg80211
---
 include/net/mac80211.h     |   34 +++++++++++++
 net/mac80211/cfg.c         |  116 +++++++++++++++++++++++++++++++++++++++++++-
 net/mac80211/driver-ops.h  |   13 +++++
 net/mac80211/ieee80211_i.h |   13 +++++
 net/mac80211/iface.c       |    2 +
 net/mac80211/trace.h       |   26 ++++++++++
 net/mac80211/tx.c          |   80 ++++++++++++++++++++++++++++++
 7 files changed, 282 insertions(+), 2 deletions(-)

Comments

Michal Kazior July 9, 2013, 7:17 a.m. UTC | #1
Hi Simon,

On 8 July 2013 15:14, Simon Wunderlich
<simon.wunderlich@s2003.tu-chemnitz.de> wrote:
> +static int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
> +                                   struct cfg80211_csa_settings *params)
> +{
> +       struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
> +       struct ieee80211_local *local = sdata->local;
> +       struct ieee80211_chanctx_conf *chanctx_conf;
> +       struct ieee80211_chanctx *chanctx;
> +       int err;
> +
> +       if (!list_empty(&local->roc_list) || local->scanning)
> +               return -EBUSY;
> +
> +       if (sdata->wdev.cac_started)
> +               return -EBUSY;
> +
> +       /* don't handle if chanctx is used */
> +       if (local->use_chanctx)
> +               return -EBUSY;
> +
> +       rcu_read_lock();
> +       chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
> +       if (!chanctx_conf) {
> +               rcu_read_unlock();
> +               return -EBUSY;
> +       }
> +
> +       /* don't handle for multi-VIF cases */
> +       chanctx = container_of(chanctx_conf, struct ieee80211_chanctx, conf);
> +       if (chanctx->refcount > 1) {
> +               rcu_read_unlock();
> +               return -EBUSY;
> +       }
> +       rcu_read_unlock();

I'm wondering if it's a huge hassle to support drivers that depend on
channel context API? Perhaps local->open_count could be used instead
of local->use_chantx and chanctx->refcount?

I'm also worried this can possibly do silly things if someone starts
an interface while CSA is under way. Consider the following:

 * start AP
 * initiate channel switch
  [ while channel switch is in progress and driver is yet to call
ieee80211_csa_finish() ]
 * start another STA interface and associate
  [ CSA completes ]

Upon CSA completion the STA will be moved to a different channel
silently and most likely end up with a beacon loss quickly. I think
mac80211 should forbid bringing up any new interfaces during CSA.

It seems there's nothing preventing from multiple calls to channel
switch callback. Is this expected? Can this work if CSA is invoked
while other CSA is still in progress?


Pozdrawiam / Best regards,
Micha? Kazior.
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Simon Wunderlich July 9, 2013, 10:27 a.m. UTC | #2
Hi Michal,

thank you for your feedback!

On Tue, Jul 09, 2013 at 09:17:41AM +0200, Michal Kazior wrote:
> Hi Simon,
> 
> On 8 July 2013 15:14, Simon Wunderlich
> <simon.wunderlich@s2003.tu-chemnitz.de> wrote:
> > +static int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
> > +                                   struct cfg80211_csa_settings *params)
> > +{
> > +       struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
> > +       struct ieee80211_local *local = sdata->local;
> > +       struct ieee80211_chanctx_conf *chanctx_conf;
> > +       struct ieee80211_chanctx *chanctx;
> > +       int err;
> > +
> > +       if (!list_empty(&local->roc_list) || local->scanning)
> > +               return -EBUSY;
> > +
> > +       if (sdata->wdev.cac_started)
> > +               return -EBUSY;
> > +
> > +       /* don't handle if chanctx is used */
> > +       if (local->use_chanctx)
> > +               return -EBUSY;
> > +
> > +       rcu_read_lock();
> > +       chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
> > +       if (!chanctx_conf) {
> > +               rcu_read_unlock();
> > +               return -EBUSY;
> > +       }
> > +
> > +       /* don't handle for multi-VIF cases */
> > +       chanctx = container_of(chanctx_conf, struct ieee80211_chanctx, conf);
> > +       if (chanctx->refcount > 1) {
> > +               rcu_read_unlock();
> > +               return -EBUSY;
> > +       }
> > +       rcu_read_unlock();
> 
> I'm wondering if it's a huge hassle to support drivers that depend on
> channel context API? Perhaps local->open_count could be used instead
> of local->use_chantx and chanctx->refcount?

Actually I'm not using any chanctx drivers, and as long as I can't test
I prefer to keep things disabled. :) local->open_count seems doable though,
it should be the same if there is only one channel context. I can change
that ... If you think it is safe I can enable support, nothing will happen
anyway as long as the driver don't set the "CSA supported" wiphy flag ...

> 
> I'm also worried this can possibly do silly things if someone starts
> an interface while CSA is under way. Consider the following:
> 
>  * start AP
>  * initiate channel switch
>   [ while channel switch is in progress and driver is yet to call
> ieee80211_csa_finish() ]
>  * start another STA interface and associate
>   [ CSA completes ]
> 
> Upon CSA completion the STA will be moved to a different channel
> silently and most likely end up with a beacon loss quickly. I think
> mac80211 should forbid bringing up any new interfaces during CSA.

I'm afraid you are right about that - there should be some check to
prevent other devices coming up during CSA. I'll add something to
prevent that.
> 
> It seems there's nothing preventing from multiple calls to channel
> switch callback. Is this expected? Can this work if CSA is invoked
> while other CSA is still in progress?

This should not happen as long as there is only one interface
doing a channel switch. If this is properly checked (need to fix
the point you mentioned above) that should be safe, I think?

Cheers,
	Simon

> 
> 
> Pozdrawiam / Best regards,
> Micha? Kazior.
Michal Kazior July 9, 2013, 2:11 p.m. UTC | #3
On 9 July 2013 12:27, Simon Wunderlich
<simon.wunderlich@s2003.tu-chemnitz.de> wrote:
> On Tue, Jul 09, 2013 at 09:17:41AM +0200, Michal Kazior wrote:
>> I'm wondering if it's a huge hassle to support drivers that depend on
>> channel context API? Perhaps local->open_count could be used instead
>> of local->use_chantx and chanctx->refcount?
>
> Actually I'm not using any chanctx drivers, and as long as I can't test
> I prefer to keep things disabled. :)

Understandable :) I'm not able to test it now either.

Hmm.. Just as an idea: mac80211_hwsim uses chanctx so it could be
modified to support CSA to test this case.


> local->open_count seems doable though,
> it should be the same if there is only one channel context. I can change
> that ... If you think it is safe I can enable support, nothing will happen
> anyway as long as the driver don't set the "CSA supported" wiphy flag ...

I looked at the code and I think local->open_count won't cut it. It
will fail with AP_VLAN interfaces present (and this isn't a problem
with your current approach). Monitor interfaces are counted in
local->monitors, but AP_VLAN aren't counted at all. mac80211 doesn't
really keep track of the number of interfaces it has reported to a
driver nor the number of software interfaces (that aren't reported to
the driver) unless I missed something.

Another idea is to verify there's exactly 1 chanctx present and it's
refcount is also 1.

CSA + chanctx is just a nice to have. If you're short on resources
it's fine the way it is I think.


>> It seems there's nothing preventing from multiple calls to channel
>> switch callback. Is this expected? Can this work if CSA is invoked
>> while other CSA is still in progress?
>
> This should not happen as long as there is only one interface
> doing a channel switch. If this is properly checked (need to fix
> the point you mentioned above) that should be safe, I think?

Yes it's okay as long as userspace doesn't do something stupid (i.e.
call channel switch more than once quickly). Whether this is a concern
is not for me to decide though.


Pozdrawiam / Best regards,
Micha? Kazior.
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diff mbox

Patch

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index aadf4eb..0eb636b 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1084,6 +1084,7 @@  enum ieee80211_vif_flags {
  * @addr: address of this interface
  * @p2p: indicates whether this AP or STA interface is a p2p
  *	interface, i.e. a GO or p2p-sta respectively
+ * @csa_active: marks whether a channel switch is going on
  * @driver_flags: flags/capabilities the driver has for this interface,
  *	these need to be set (or cleared) when the interface is added
  *	or, if supported by the driver, the interface type is changed
@@ -1106,6 +1107,7 @@  struct ieee80211_vif {
 	struct ieee80211_bss_conf bss_conf;
 	u8 addr[ETH_ALEN];
 	bool p2p;
+	bool csa_active;
 
 	u8 cab_queue;
 	u8 hw_queue[IEEE80211_NUM_ACS];
@@ -2637,6 +2639,16 @@  enum ieee80211_roc_type {
  * @ipv6_addr_change: IPv6 address assignment on the given interface changed.
  *	Currently, this is only called for managed or P2P client interfaces.
  *	This callback is optional; it must not sleep.
+ *
+ * @channel_switch_beacon: Starts a channel switch to a new channel.
+ *	Beacons are modified to include CSA or ECSA IEs before calling this
+ *	function. The corresponding count fields in these IEs must be
+ *	decremented, and when they reach zero the driver must call
+ *	ieee80211_csa_finish(). Drivers which use ieee80211_beacon_get()
+ *	get the csa counter decremented by mac80211, but must check if it is
+ *	zero using ieee80211_csa_is_complete() after the beacon has been
+ *	transmitted and then call ieee80211_csa_finish().
+ *
  */
 struct ieee80211_ops {
 	void (*tx)(struct ieee80211_hw *hw,
@@ -2824,6 +2836,9 @@  struct ieee80211_ops {
 				 struct ieee80211_vif *vif,
 				 struct inet6_dev *idev);
 #endif
+	void (*channel_switch_beacon)(struct ieee80211_hw *hw,
+				      struct ieee80211_vif *vif,
+				      struct cfg80211_chan_def *chandef);
 };
 
 /**
@@ -3319,6 +3334,25 @@  static inline struct sk_buff *ieee80211_beacon_get(struct ieee80211_hw *hw,
 }
 
 /**
+ * ieee80211_csa_finish - notify mac80211 about channel switch
+ * @vif: &struct ieee80211_vif pointer from the add_interface callback.
+ *
+ * After a channel switch announcement was scheduled and the counter in this
+ * announcement hit zero, this function must be called by the driver to
+ * notify mac80211 that the channel can be changed.
+ */
+void ieee80211_csa_finish(struct ieee80211_vif *vif);
+
+/**
+ * ieee80211_csa_is_complete - find out if counters reached zero
+ * @vif: &struct ieee80211_vif pointer from the add_interface callback.
+ *
+ * This function returns whether the channel switch counters reached zero.
+ */
+bool ieee80211_csa_is_complete(struct ieee80211_vif *vif);
+
+
+/**
  * ieee80211_proberesp_get - retrieve a Probe Response template
  * @hw: pointer obtained from ieee80211_alloc_hw().
  * @vif: &struct ieee80211_vif pointer from the add_interface callback.
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index a99c9a8..b32e4db 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -854,8 +854,8 @@  static int ieee80211_set_probe_resp(struct ieee80211_sub_if_data *sdata,
 	return 0;
 }
 
-static int ieee80211_assign_beacon(struct ieee80211_sub_if_data *sdata,
-				   struct cfg80211_beacon_data *params)
+int ieee80211_assign_beacon(struct ieee80211_sub_if_data *sdata,
+			    struct cfg80211_beacon_data *params)
 {
 	struct beacon_data *new, *old;
 	int new_head_len, new_tail_len;
@@ -1018,6 +1018,12 @@  static int ieee80211_change_beacon(struct wiphy *wiphy, struct net_device *dev,
 
 	sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
+	/* don't allow changing the beacon while CSA is in place - offset
+	 * of channel switch counter may change
+	 */
+	if (sdata->vif.csa_active)
+		return -EBUSY;
+
 	old = rtnl_dereference(sdata->u.ap.beacon);
 	if (!old)
 		return -ENOENT;
@@ -2840,6 +2846,111 @@  cfg80211_beacon_dup(struct cfg80211_beacon_data *beacon)
 	return new_beacon;
 }
 
+void ieee80211_csa_finalize_work(struct work_struct *work)
+{
+	struct ieee80211_sub_if_data *sdata =
+		container_of(work, struct ieee80211_sub_if_data,
+			     csa_finalize_work);
+	struct ieee80211_local *local = sdata->local;
+	int err, changed;
+
+	if (!ieee80211_sdata_running(sdata))
+		return;
+
+	if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_AP))
+		return;
+
+	sdata->radar_required = sdata->csa_radar_required;
+	err = ieee80211_vif_change_channel(sdata, &local->csa_chandef,
+					   &changed);
+	if (WARN_ON(err < 0))
+		return;
+
+	err = ieee80211_assign_beacon(sdata, sdata->u.ap.next_beacon);
+	if (err < 0)
+		return;
+
+	changed |= err;
+	kfree(sdata->u.ap.next_beacon);
+	sdata->u.ap.next_beacon = NULL;
+
+	ieee80211_wake_queues_by_reason(&sdata->local->hw,
+					IEEE80211_MAX_QUEUE_MAP,
+					IEEE80211_QUEUE_STOP_REASON_CSA);
+
+	ieee80211_bss_info_change_notify(sdata, changed);
+
+	cfg80211_ch_switch_notify(sdata->dev, &local->csa_chandef);
+}
+
+static int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
+				    struct cfg80211_csa_settings *params)
+{
+	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_chanctx_conf *chanctx_conf;
+	struct ieee80211_chanctx *chanctx;
+	int err;
+
+	if (!list_empty(&local->roc_list) || local->scanning)
+		return -EBUSY;
+
+	if (sdata->wdev.cac_started)
+		return -EBUSY;
+
+	/* don't handle if chanctx is used */
+	if (local->use_chanctx)
+		return -EBUSY;
+
+	rcu_read_lock();
+	chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
+	if (!chanctx_conf) {
+		rcu_read_unlock();
+		return -EBUSY;
+	}
+
+	/* don't handle for multi-VIF cases */
+	chanctx = container_of(chanctx_conf, struct ieee80211_chanctx, conf);
+	if (chanctx->refcount > 1) {
+		rcu_read_unlock();
+		return -EBUSY;
+	}
+	rcu_read_unlock();
+
+	/* only handle AP for now. */
+	switch (sdata->vif.type) {
+	case NL80211_IFTYPE_AP:
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	sdata->u.ap.next_beacon = cfg80211_beacon_dup(&params->beacon_after);
+	if (!sdata->u.ap.next_beacon)
+		return -ENOMEM;
+
+	sdata->csa_counter_offset_beacon = params->counter_offset_beacon;
+	sdata->csa_counter_offset_presp = params->counter_offset_presp;
+	sdata->csa_radar_required = params->radar_required;
+
+	if (params->block_tx)
+		ieee80211_stop_queues_by_reason(&local->hw,
+				IEEE80211_MAX_QUEUE_MAP,
+				IEEE80211_QUEUE_STOP_REASON_CSA);
+
+	err = ieee80211_assign_beacon(sdata, &params->beacon_csa);
+	if (err < 0)
+		return err;
+
+	local->csa_chandef = params->chandef;
+	sdata->vif.csa_active = true;
+
+	ieee80211_bss_info_change_notify(sdata, err);
+	drv_channel_switch_beacon(sdata, &params->chandef);
+
+	return 0;
+}
+
 static int ieee80211_mgmt_tx(struct wiphy *wiphy, struct wireless_dev *wdev,
 			     struct ieee80211_channel *chan, bool offchan,
 			     unsigned int wait, const u8 *buf, size_t len,
@@ -3557,4 +3668,5 @@  struct cfg80211_ops mac80211_config_ops = {
 	.get_et_strings = ieee80211_get_et_strings,
 	.get_channel = ieee80211_cfg_get_channel,
 	.start_radar_detection = ieee80211_start_radar_detection,
+	.channel_switch = ieee80211_channel_switch,
 };
diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index b931c96..b3ea11f 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -1072,4 +1072,17 @@  static inline void drv_ipv6_addr_change(struct ieee80211_local *local,
 }
 #endif
 
+static inline void
+drv_channel_switch_beacon(struct ieee80211_sub_if_data *sdata,
+			  struct cfg80211_chan_def *chandef)
+{
+	struct ieee80211_local *local = sdata->local;
+
+	if (local->ops->channel_switch_beacon) {
+		trace_drv_channel_switch_beacon(local, sdata, chandef);
+		local->ops->channel_switch_beacon(&local->hw, &sdata->vif,
+						  chandef);
+	}
+}
+
 #endif /* __MAC80211_DRIVER_OPS */
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index e34eb5f..2a22379 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -259,6 +259,8 @@  struct ieee80211_if_ap {
 	struct beacon_data __rcu *beacon;
 	struct probe_resp __rcu *probe_resp;
 
+	/* to be used after channel switch. */
+	struct cfg80211_beacon_data *next_beacon;
 	struct list_head vlans;
 
 	struct ps_data ps;
@@ -716,6 +718,11 @@  struct ieee80211_sub_if_data {
 
 	struct ieee80211_tx_queue_params tx_conf[IEEE80211_NUM_ACS];
 
+	struct work_struct csa_finalize_work;
+	int csa_counter_offset_beacon;
+	int csa_counter_offset_presp;
+	bool csa_radar_required;
+
 	/* used to reconfigure hardware SM PS */
 	struct work_struct recalc_smps;
 
@@ -1344,6 +1351,9 @@  void ieee80211_roc_notify_destroy(struct ieee80211_roc_work *roc, bool free);
 void ieee80211_sw_roc_work(struct work_struct *work);
 void ieee80211_handle_roc_started(struct ieee80211_roc_work *roc);
 
+/* channel switch handling */
+void ieee80211_csa_finalize_work(struct work_struct *work);
+
 /* interface handling */
 int ieee80211_iface_init(void);
 void ieee80211_iface_exit(void);
@@ -1365,6 +1375,9 @@  void ieee80211_del_virtual_monitor(struct ieee80211_local *local);
 
 bool __ieee80211_recalc_txpower(struct ieee80211_sub_if_data *sdata);
 void ieee80211_recalc_txpower(struct ieee80211_sub_if_data *sdata);
+int ieee80211_assign_beacon(struct ieee80211_sub_if_data *sdata,
+			    struct cfg80211_beacon_data *params);
+
 
 static inline bool ieee80211_sdata_running(struct ieee80211_sub_if_data *sdata)
 {
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index a2a8250..671fe7c 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -804,6 +804,7 @@  static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
 	cancel_work_sync(&local->dynamic_ps_enable_work);
 
 	cancel_work_sync(&sdata->recalc_smps);
+	cancel_work_sync(&sdata->csa_finalize_work);
 
 	cancel_delayed_work_sync(&sdata->dfs_cac_timer_work);
 
@@ -1267,6 +1268,7 @@  static void ieee80211_setup_sdata(struct ieee80211_sub_if_data *sdata,
 	skb_queue_head_init(&sdata->skb_queue);
 	INIT_WORK(&sdata->work, ieee80211_iface_work);
 	INIT_WORK(&sdata->recalc_smps, ieee80211_recalc_smps_work);
+	INIT_WORK(&sdata->csa_finalize_work, ieee80211_csa_finalize_work);
 
 	switch (type) {
 	case NL80211_IFTYPE_P2P_GO:
diff --git a/net/mac80211/trace.h b/net/mac80211/trace.h
index c215fafd7..1aba645 100644
--- a/net/mac80211/trace.h
+++ b/net/mac80211/trace.h
@@ -1906,6 +1906,32 @@  TRACE_EVENT(api_radar_detected,
 	)
 );
 
+TRACE_EVENT(drv_channel_switch_beacon,
+	TP_PROTO(struct ieee80211_local *local,
+		 struct ieee80211_sub_if_data *sdata,
+		 struct cfg80211_chan_def *chandef),
+
+	TP_ARGS(local, sdata, chandef),
+
+	TP_STRUCT__entry(
+		LOCAL_ENTRY
+		VIF_ENTRY
+		CHANDEF_ENTRY
+	),
+
+	TP_fast_assign(
+		LOCAL_ASSIGN;
+		VIF_ASSIGN;
+		CHANDEF_ASSIGN(chandef);
+	),
+
+	TP_printk(
+		LOCAL_PR_FMT VIF_PR_FMT " channel switch to " CHANDEF_PR_FMT,
+		LOCAL_PR_ARG, VIF_PR_ARG, CHANDEF_PR_ARG
+	)
+);
+
+
 #ifdef CONFIG_MAC80211_MESSAGE_TRACING
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM mac80211_msg
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 4105d0c..76b2538 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2320,6 +2320,83 @@  static int ieee80211_beacon_add_tim(struct ieee80211_sub_if_data *sdata,
 	return 0;
 }
 
+void ieee80211_csa_finish(struct ieee80211_vif *vif)
+{
+	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
+
+	vif->csa_active = false;
+	ieee80211_queue_work(&sdata->local->hw,
+			     &sdata->csa_finalize_work);
+}
+EXPORT_SYMBOL(ieee80211_csa_finish);
+
+static void ieee80211_update_csa(struct ieee80211_sub_if_data *sdata,
+				 struct beacon_data *beacon)
+{
+	struct probe_resp *resp;
+	int counter_offset_beacon = sdata->csa_counter_offset_beacon;
+	int counter_offset_presp = sdata->csa_counter_offset_presp;
+
+	/* warn if the driver did not check for/react to csa completeness */
+	if (WARN_ON(((u8 *)beacon->tail)[counter_offset_beacon] == 0))
+		return;
+
+	((u8 *)beacon->tail)[counter_offset_beacon]--;
+
+	if (!counter_offset_presp)
+		return;
+
+	if (sdata->vif.type == NL80211_IFTYPE_AP) {
+		rcu_read_lock();
+		resp = rcu_dereference(sdata->u.ap.probe_resp);
+
+		/* if nl80211 accepted the offset, this should not happen. */
+		if (WARN_ON(!resp)) {
+			rcu_read_unlock();
+			return;
+		}
+		resp->data[counter_offset_presp]--;
+	}
+}
+
+bool ieee80211_csa_is_complete(struct ieee80211_vif *vif)
+{
+	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
+	struct beacon_data *beacon = NULL;
+	u8 *beacon_data;
+	size_t beacon_data_len;
+	int counter_beacon = sdata->csa_counter_offset_beacon;
+	int ret = false;
+
+	if (!ieee80211_sdata_running(sdata))
+		return false;
+
+	rcu_read_lock();
+	if (vif->type == NL80211_IFTYPE_AP) {
+		struct ieee80211_if_ap *ap = &sdata->u.ap;
+
+		beacon = rcu_dereference(ap->beacon);
+		if (WARN_ON(!beacon || !beacon->tail))
+			goto out;
+		beacon_data = beacon->tail;
+		beacon_data_len = beacon->tail_len;
+	} else {
+		WARN_ON(1);
+		goto out;
+	}
+
+	if (WARN_ON(counter_beacon > beacon_data_len))
+		goto out;
+
+	if (beacon_data[counter_beacon] == 0)
+		ret = true;
+ out:
+	rcu_read_unlock();
+
+	return ret;
+}
+EXPORT_SYMBOL(ieee80211_csa_is_complete);
+
 struct sk_buff *ieee80211_beacon_get_tim(struct ieee80211_hw *hw,
 					 struct ieee80211_vif *vif,
 					 u16 *tim_offset, u16 *tim_length)
@@ -2350,6 +2427,9 @@  struct sk_buff *ieee80211_beacon_get_tim(struct ieee80211_hw *hw,
 		struct beacon_data *beacon = rcu_dereference(ap->beacon);
 
 		if (beacon) {
+			if (sdata->vif.csa_active)
+				ieee80211_update_csa(sdata, beacon);
+
 			/*
 			 * headroom, head length,
 			 * tail length and maximum TIM length