[PATCH v4 1/5] mac80211: refactor ieee80211_ibss_process_chanswitch()

[PATCH v4 1/5] mac80211: refactor ieee80211_ibss_process_chanswitch()

[Luciano Coelho]

Refactor ieee80211_ibss_process_chanswitch() to use
ieee80211_channel_switch() and avoid code duplication.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
---
 net/mac80211/cfg.c         |  4 ++--
 net/mac80211/ibss.c        | 58 +++++++---------------------------------------
 net/mac80211/ieee80211_i.h |  2 ++
 3 files changed, 12 insertions(+), 52 deletions(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 11ddb34..87b2533 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -3014,8 +3014,8 @@ void ieee80211_csa_finalize_work(struct work_struct *work)
 	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)
+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;
diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index 531be04..548eae8 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -784,18 +784,10 @@ ieee80211_ibss_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 	struct cfg80211_csa_settings params;
 	struct ieee80211_csa_ie csa_ie;
 	struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
-	struct ieee80211_chanctx_conf *chanctx_conf;
-	struct ieee80211_chanctx *chanctx;
 	enum nl80211_channel_type ch_type;
-	int err, num_chanctx;
+	int err;
 	u32 sta_flags;
 
-	if (sdata->vif.csa_active)
-		return true;
-
-	if (!sdata->vif.bss_conf.ibss_joined)
-		return false;
-
 	sta_flags = IEEE80211_STA_DISABLE_VHT;
 	switch (ifibss->chandef.width) {
 	case NL80211_CHAN_WIDTH_5:
@@ -826,9 +818,6 @@ ieee80211_ibss_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 	params.count = csa_ie.count;
 	params.chandef = csa_ie.chandef;
 
-	if (ifibss->chandef.chan->band != params.chandef.chan->band)
-		goto disconnect;
-
 	switch (ifibss->chandef.width) {
 	case NL80211_CHAN_WIDTH_20_NOHT:
 	case NL80211_CHAN_WIDTH_20:
@@ -884,29 +873,6 @@ ieee80211_ibss_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 		params.radar_required = true;
 	}
 
-	rcu_read_lock();
-	chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
-	if (!chanctx_conf) {
-		rcu_read_unlock();
-		goto disconnect;
-	}
-
-	/* don't handle for multi-VIF cases */
-	chanctx = container_of(chanctx_conf, struct ieee80211_chanctx, conf);
-	if (chanctx->refcount > 1) {
-		rcu_read_unlock();
-		goto disconnect;
-	}
-	num_chanctx = 0;
-	list_for_each_entry_rcu(chanctx, &sdata->local->chanctx_list, list)
-		num_chanctx++;
-
-	if (num_chanctx > 1) {
-		rcu_read_unlock();
-		goto disconnect;
-	}
-	rcu_read_unlock();
-
 	/* all checks done, now perform the channel switch. */
 	ibss_dbg(sdata,
 		 "received channel switch announcement to go to channel %d MHz\n",
@@ -914,19 +880,9 @@ ieee80211_ibss_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 
 	params.block_tx = !!csa_ie.mode;
 
-	ieee80211_ibss_csa_beacon(sdata, &params);
-	sdata->csa_radar_required = params.radar_required;
-
-	if (params.block_tx)
-		ieee80211_stop_queues_by_reason(&sdata->local->hw,
-				IEEE80211_MAX_QUEUE_MAP,
-				IEEE80211_QUEUE_STOP_REASON_CSA);
-
-	sdata->local->csa_chandef = params.chandef;
-	sdata->vif.csa_active = true;
-
-	ieee80211_bss_info_change_notify(sdata, err);
-	drv_channel_switch_beacon(sdata, &params.chandef);
+	if (ieee80211_channel_switch(sdata->local->hw.wiphy, sdata->dev,
+				     &params))
+		goto disconnect;
 
 	ieee80211_ibss_csa_mark_radar(sdata);
 
@@ -962,7 +918,8 @@ ieee80211_rx_mgmt_spectrum_mgmt(struct ieee80211_sub_if_data *sdata,
 	if (len < required_len)
 		return;
 
-	ieee80211_ibss_process_chanswitch(sdata, elems, false);
+	if (!sdata->vif.csa_active)
+		ieee80211_ibss_process_chanswitch(sdata, elems, false);
 }
 
 static void ieee80211_rx_mgmt_deauth_ibss(struct ieee80211_sub_if_data *sdata,
@@ -1143,7 +1100,8 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 		goto put_bss;
 
 	/* process channel switch */
-	if (ieee80211_ibss_process_chanswitch(sdata, elems, true))
+	if (sdata->vif.csa_active ||
+	    ieee80211_ibss_process_chanswitch(sdata, elems, true))
 		goto put_bss;
 
 	/* same BSSID */
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 4aea4e7..f4af05d 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1415,6 +1415,8 @@ void ieee80211_handle_roc_started(struct ieee80211_roc_work *roc);
 
 /* channel switch handling */
 void ieee80211_csa_finalize_work(struct work_struct *work);
+int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
+			     struct cfg80211_csa_settings *params);
 
 /* interface handling */
 int ieee80211_iface_init(void);
-- 
1.8.4.rc3

[PATCH v4 2/5] mac80211: align ieee80211_ibss_csa_beacon() with ieee80211_csa_beacon()

[Luciano Coelho]

The return value of ieee80211_ibss_csa_beacon is not aligned with the
return value of ieee80211_csa_beacon().  For consistency and to be
able to use both functions with similar code, change
ieee80211_ibss_csa_beacon() not to send the bss changed notification
itself, but return what has changed so the caller can send the
notification instead.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
---

In v4:

   * use goto out instead of sdata_unlock and return in the middle of
     the flow; (Ilan)

 net/mac80211/ibss.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index 548eae8..3300209 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -522,7 +522,7 @@ int ieee80211_ibss_csa_beacon(struct ieee80211_sub_if_data *sdata,
 	if (csa_settings)
 		ieee80211_send_action_csa(sdata, csa_settings);
 
-	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
+	return BSS_CHANGED_BEACON;
  out:
 	return ret;
 }
@@ -559,11 +559,17 @@ int ieee80211_ibss_finish_csa(struct ieee80211_sub_if_data *sdata)
 
 	/* generate the beacon */
 	err = ieee80211_ibss_csa_beacon(sdata, NULL);
-	sdata_unlock(sdata);
 	if (err < 0)
-		return err;
+		goto out;
 
-	return 0;
+	if (err) {
+		ieee80211_bss_info_change_notify(sdata, err);
+		err = 0;
+	}
+out:
+	sdata_unlock(sdata);
+
+	return err;
 }
 
 void ieee80211_ibss_stop(struct ieee80211_sub_if_data *sdata)
-- 
1.8.4.rc3

[PATCH v4 3/5] mac80211: refactor ieee80211_mesh_process_chanswitch()

[Luciano Coelho]

Refactor ieee80211_mesh_process_chanswitch() to use
ieee80211_channel_switch() and avoid code duplication.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
---

This depends on Chun-Yeow's "mac80211: fix the mesh channel switch
support", which Johannes already applied but is not in
wireless-testing yet.

 net/mac80211/cfg.c         | 16 +++++++-----
 net/mac80211/ieee80211_i.h |  1 +
 net/mac80211/mesh.c        | 64 ++++++++--------------------------------------
 3 files changed, 22 insertions(+), 59 deletions(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 87b2533..e242862 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -3120,15 +3120,19 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 		    params->chandef.chan->band)
 			return -EINVAL;
 
-		ifmsh->chsw_init = true;
-		if (!ifmsh->pre_value)
-			ifmsh->pre_value = 1;
-		else
-			ifmsh->pre_value++;
+		if (!ifmsh->csa_repeater) {
+			ifmsh->chsw_init = true;
+			if (!ifmsh->pre_value)
+				ifmsh->pre_value = 1;
+			else
+				ifmsh->pre_value++;
+		}
 
-		err = ieee80211_mesh_csa_beacon(sdata, params, true);
+		err = ieee80211_mesh_csa_beacon(sdata, params,
+						ifmsh->chsw_init);
 		if (err < 0) {
 			ifmsh->chsw_init = false;
+			ifmsh->csa_repeater = false;
 			return err;
 		}
 		break;
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index f4af05d..bba7897 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -612,6 +612,7 @@ struct ieee80211_if_mesh {
 	/* Channel Switching Support */
 	struct mesh_csa_settings __rcu *csa;
 	bool chsw_init;
+	bool csa_repeater;
 	u8 chsw_ttl;
 	u16 pre_value;
 };
diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index ba10525..a2344fc 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -856,19 +856,11 @@ ieee80211_mesh_process_chnswitch(struct ieee80211_sub_if_data *sdata,
 {
 	struct cfg80211_csa_settings params;
 	struct ieee80211_csa_ie csa_ie;
-	struct ieee80211_chanctx_conf *chanctx_conf;
-	struct ieee80211_chanctx *chanctx;
 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
 	enum ieee80211_band band = ieee80211_get_sdata_band(sdata);
-	int err, num_chanctx;
+	int err;
 	u32 sta_flags;
 
-	if (sdata->vif.csa_active)
-		return true;
-
-	if (!ifmsh->mesh_id)
-		return false;
-
 	sta_flags = IEEE80211_STA_DISABLE_VHT;
 	switch (sdata->vif.bss_conf.chandef.width) {
 	case NL80211_CHAN_WIDTH_20_NOHT:
@@ -893,10 +885,6 @@ ieee80211_mesh_process_chnswitch(struct ieee80211_sub_if_data *sdata,
 	params.chandef = csa_ie.chandef;
 	params.count = csa_ie.count;
 
-	if (sdata->vif.bss_conf.chandef.chan->band !=
-	    params.chandef.chan->band)
-		return false;
-
 	if (!cfg80211_chandef_usable(sdata->local->hw.wiphy, &params.chandef,
 				     IEEE80211_CHAN_DISABLED)) {
 		sdata_info(sdata,
@@ -919,25 +907,6 @@ ieee80211_mesh_process_chnswitch(struct ieee80211_sub_if_data *sdata,
 		return false;
 	}
 
-	rcu_read_lock();
-	chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
-	if (!chanctx_conf)
-		goto failed_chswitch;
-
-	/* don't handle for multi-VIF cases */
-	chanctx = container_of(chanctx_conf, struct ieee80211_chanctx, conf);
-	if (chanctx->refcount > 1)
-		goto failed_chswitch;
-
-	num_chanctx = 0;
-	list_for_each_entry_rcu(chanctx, &sdata->local->chanctx_list, list)
-		num_chanctx++;
-
-	if (num_chanctx > 1)
-		goto failed_chswitch;
-
-	rcu_read_unlock();
-
 	mcsa_dbg(sdata,
 		 "received channel switch announcement to go to channel %d MHz\n",
 		 params.chandef.chan->center_freq);
@@ -950,30 +919,16 @@ ieee80211_mesh_process_chnswitch(struct ieee80211_sub_if_data *sdata,
 		ifmsh->pre_value = csa_ie.pre_value;
 	}
 
-	if (ifmsh->chsw_ttl < ifmsh->mshcfg.dot11MeshTTL) {
-		if (ieee80211_mesh_csa_beacon(sdata, &params, false) < 0)
-			return false;
-	} else {
+	if (ifmsh->chsw_ttl >= ifmsh->mshcfg.dot11MeshTTL)
 		return false;
-	}
-
-	sdata->csa_radar_required = params.radar_required;
-
-	if (params.block_tx)
-		ieee80211_stop_queues_by_reason(&sdata->local->hw,
-				IEEE80211_MAX_QUEUE_MAP,
-				IEEE80211_QUEUE_STOP_REASON_CSA);
 
-	sdata->local->csa_chandef = params.chandef;
-	sdata->vif.csa_active = true;
+	ifmsh->csa_repeater = true;
 
-	ieee80211_bss_info_change_notify(sdata, err);
-	drv_channel_switch_beacon(sdata, &params.chandef);
+	if (ieee80211_channel_switch(sdata->local->hw.wiphy, sdata->dev,
+				     &params) < 0)
+		return false;
 
 	return true;
-failed_chswitch:
-	rcu_read_unlock();
-	return false;
 }
 
 static void
@@ -1083,7 +1038,7 @@ static void ieee80211_mesh_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
 		ifmsh->sync_ops->rx_bcn_presp(sdata,
 			stype, mgmt, &elems, rx_status);
 
-	if (!ifmsh->chsw_init)
+	if (!ifmsh->chsw_init && !sdata->vif.csa_active)
 		ieee80211_mesh_process_chnswitch(sdata, &elems, true);
 }
 
@@ -1095,6 +1050,7 @@ int ieee80211_mesh_finish_csa(struct ieee80211_sub_if_data *sdata)
 
 	/* Reset the TTL value and Initiator flag */
 	ifmsh->chsw_init = false;
+	ifmsh->csa_repeater = false;
 	ifmsh->chsw_ttl = 0;
 
 	/* Remove the CSA and MCSP elements from the beacon */
@@ -1207,7 +1163,8 @@ static void mesh_rx_csa_frame(struct ieee80211_sub_if_data *sdata,
 
 	ifmsh->pre_value = pre_value;
 
-	if (!ieee80211_mesh_process_chnswitch(sdata, &elems, false)) {
+	if (!sdata->vif.csa_active &&
+	    !ieee80211_mesh_process_chnswitch(sdata, &elems, false)) {
 		mcsa_dbg(sdata, "Failed to process CSA action frame");
 		return;
 	}
@@ -1363,6 +1320,7 @@ void ieee80211_mesh_init_sdata(struct ieee80211_sub_if_data *sdata)
 	ifmsh->last_preq = jiffies;
 	ifmsh->next_perr = jiffies;
 	ifmsh->chsw_init = false;
+	ifmsh->csa_repeater = false;
 	/* Allocate all mesh structures when creating the first mesh interface. */
 	if (!mesh_allocated)
 		ieee80211s_init();
-- 
1.8.4.rc3

[PATCH v4 4/5] mac80211: align ieee80211_mesh_csa_beacon() with ieee80211_csa_beacon()

[Luciano Coelho]

The return value of ieee80211_mesh_csa_beacon is not aligned with the
return value of ieee80211_csa_beacon() and
ieee80211_ibss_csa_beacon().  For consistency and to be able to use
both functions with similar code, change ieee80211_mesh_csa_beacon()
not to send the bss changed notification itself, but return what has
changed so the caller can send the notification instead.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
---

This depends on Chun-Yeow's "mac80211: fix the mesh channel switch
support", which Johannes already applied but is not in
wireless-testing yet.

 net/mac80211/cfg.c  | 2 ++
 net/mac80211/mesh.c | 4 +---
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index e242862..fc5a1f9 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -3135,6 +3135,8 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 			ifmsh->csa_repeater = false;
 			return err;
 		}
+		changed |= err;
+
 		break;
 #endif
 	default:
diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index a2344fc..6d6c56b 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -1094,12 +1094,10 @@ int ieee80211_mesh_csa_beacon(struct ieee80211_sub_if_data *sdata,
 		return ret;
 	}
 
-	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
-
 	if (csa_action)
 		ieee80211_send_action_csa(sdata, csa_settings);
 
-	return 0;
+	return BSS_CHANGED_BEACON;
 }
 
 static int mesh_fwd_csa_frame(struct ieee80211_sub_if_data *sdata,
-- 
1.8.4.rc3

[PATCH v4 5/5] mac80211: only set CSA beacon when at least one beacon must be transmitted

[Luciano Coelho]

A beacon should never have a Channel Switch Announcement information
element with a count of 0, because a count of 1 means switch just
before the next beacon.  So, if a count of 0 was valid in a beacon, it
would have been transmitted in the next channel already, which is
useless.  A CSA count equal to zero is only meaningful in action
frames or probe_responses.

Fix the ieee80211_csa_is_complete() and ieee80211_update_csa()
functions accordingly.

With a CSA count of 0, we won't transmit any CSA beacons, because the
switch will happen before the next TBTT.  To avoid extra work and
potential confusion in the drivers, complete the CSA immediately,
instead of waiting for the driver to call ieee80211_csa_finish().

To keep things simpler, we also switch immediately when the CSA count
is 1, while in theory we should delay the switch until just before the
next TBTT.

Additionally, move the ieee80211_csa_finish() function to cfg.c,
where it makes more sense.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
---

In v3:

* moved the documentation change that explains that the
  channel_switch_beacon() driver op is not called when count <= 1;

* call finalize work immediately instead doing it through the
  workqueue.

* instead of checking (params->count > 1), check the changed variable
  to decide whether to call drv_channel_switch_beacon() (and
  ieee80211_bss_info_change_notify() as well);

In v4:

* moved the call to csa_finalize() outside the switch, so all the
  sdata->csa_* parameters are correctly set; (thanks Andrei)

* squashed the "mac80211: don't transmit beacon with CSA count 0"
  patch into this one;

* in IBSS mode, send the CSA action frame also when count <= 1;

* added changes for the recently merged mesh CSA patches;


 include/net/mac80211.h     | 10 +++--
 net/mac80211/cfg.c         | 98 +++++++++++++++++++++++++++++++++++-----------
 net/mac80211/ibss.c        |  6 ---
 net/mac80211/ieee80211_i.h |  3 +-
 net/mac80211/mesh.c        |  6 +--
 net/mac80211/tx.c          | 19 ++++-----
 6 files changed, 90 insertions(+), 52 deletions(-)

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 7ceed99..f08c76a 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -2680,11 +2680,13 @@ enum ieee80211_roc_type {
  * @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
+ *	decremented, and when they reach 1 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
+ *	1 using ieee80211_csa_is_complete() after the beacon has been
  *	transmitted and then call ieee80211_csa_finish().
+ *	If the CSA count starts as zero or 1, this function will not be called,
+ *	since there won't be any time to beacon before the switch anyway.
  *
  * @join_ibss: Join an IBSS (on an IBSS interface); this is called after all
  *	information in bss_conf is set up and the beacon can be retrieved. A
@@ -3383,13 +3385,13 @@ static inline struct sk_buff *ieee80211_beacon_get(struct ieee80211_hw *hw,
  * @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
+ * announcement hits 1, 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
+ * ieee80211_csa_is_complete - find out if counters reached 1
  * @vif: &struct ieee80211_vif pointer from the add_interface callback.
  *
  * This function returns whether the channel switch counters reached zero.
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index fc5a1f9..2cf4476 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -2956,17 +2956,20 @@ cfg80211_beacon_dup(struct cfg80211_beacon_data *beacon)
 	return new_beacon;
 }
 
-void ieee80211_csa_finalize_work(struct work_struct *work)
+void ieee80211_csa_finish(struct ieee80211_vif *vif)
+{
+	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
+
+	ieee80211_queue_work(&sdata->local->hw,
+			     &sdata->csa_finalize_work);
+}
+EXPORT_SYMBOL(ieee80211_csa_finish);
+
+static void ieee80211_csa_finalize(struct ieee80211_sub_if_data *sdata)
 {
-	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 = 0;
 
-	if (!ieee80211_sdata_running(sdata))
-		return;
-
 	sdata->radar_required = sdata->csa_radar_required;
 	err = ieee80211_vif_change_channel(sdata, &local->csa_chandef,
 					   &changed);
@@ -3014,6 +3017,18 @@ void ieee80211_csa_finalize_work(struct work_struct *work)
 	cfg80211_ch_switch_notify(sdata->dev, &local->csa_chandef);
 }
 
+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);
+
+	if (!ieee80211_sdata_running(sdata))
+		return;
+
+	ieee80211_csa_finalize(sdata);
+}
+
 int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 			     struct cfg80211_csa_settings *params)
 {
@@ -3022,7 +3037,7 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 	struct ieee80211_chanctx_conf *chanctx_conf;
 	struct ieee80211_chanctx *chanctx;
 	struct ieee80211_if_mesh __maybe_unused *ifmsh;
-	int err, num_chanctx;
+	int err, num_chanctx, changed = 0;
 
 	if (!list_empty(&local->roc_list) || local->scanning)
 		return -EBUSY;
@@ -3061,19 +3076,40 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 
 	switch (sdata->vif.type) {
 	case NL80211_IFTYPE_AP:
-		sdata->csa_counter_offset_beacon =
-			params->counter_offset_beacon;
-		sdata->csa_counter_offset_presp = params->counter_offset_presp;
 		sdata->u.ap.next_beacon =
 			cfg80211_beacon_dup(&params->beacon_after);
 		if (!sdata->u.ap.next_beacon)
 			return -ENOMEM;
 
+		/*
+		 * With a count of 0, we don't have to wait for any
+		 * TBTT before switching, so complete the CSA
+		 * immediately.  In theory, with a count == 1 we
+		 * should delay the switch until just before the next
+		 * TBTT, but that would complicate things so we switch
+		 * immediately too.  If we would delay the switch
+		 * until the next TBTT, we would have to set the probe
+		 * response here.
+		 *
+		 * TODO: A channel switch with count <= 1 without
+		 * sending a CSA action frame is kind of useless,
+		 * because the clients won't know we're changing
+		 * channels.  The action frame must be implemented
+		 * either here or in the userspace.
+		 */
+		if (params->count <= 1)
+			break;
+
+		sdata->csa_counter_offset_beacon =
+			params->counter_offset_beacon;
+		sdata->csa_counter_offset_presp = params->counter_offset_presp;
 		err = ieee80211_assign_beacon(sdata, &params->beacon_csa);
 		if (err < 0) {
 			kfree(sdata->u.ap.next_beacon);
 			return err;
 		}
+		changed |= err;
+
 		break;
 	case NL80211_IFTYPE_ADHOC:
 		if (!sdata->vif.bss_conf.ibss_joined)
@@ -3101,9 +3137,16 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 		    params->chandef.chan->band)
 			return -EINVAL;
 
-		err = ieee80211_ibss_csa_beacon(sdata, params);
-		if (err < 0)
-			return err;
+		/* see comments and TODO in the NL80211_IFTYPE_AP block */
+		if (params->count > 1) {
+			err = ieee80211_ibss_csa_beacon(sdata, params);
+			if (err < 0)
+				return err;
+			changed |= err;
+		}
+
+		ieee80211_send_action_csa(sdata, params);
+
 		break;
 #ifdef CONFIG_MAC80211_MESH
 	case NL80211_IFTYPE_MESH_POINT:
@@ -3128,14 +3171,18 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 				ifmsh->pre_value++;
 		}
 
-		err = ieee80211_mesh_csa_beacon(sdata, params,
-						ifmsh->chsw_init);
-		if (err < 0) {
-			ifmsh->chsw_init = false;
-			ifmsh->csa_repeater = false;
-			return err;
+		if (params->count > 1) {
+			err = ieee80211_mesh_csa_beacon(sdata, params);
+			if (err < 0) {
+				ifmsh->chsw_init = false;
+				ifmsh->csa_repeater = false;
+				return err;
+			}
+			changed |= err;
 		}
-		changed |= err;
+
+		if (ifmsh->chsw_init)
+			ieee80211_send_action_csa(sdata, params);
 
 		break;
 #endif
@@ -3153,8 +3200,13 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 	local->csa_chandef = params->chandef;
 	sdata->vif.csa_active = true;
 
-	ieee80211_bss_info_change_notify(sdata, err);
-	drv_channel_switch_beacon(sdata, &params->chandef);
+	if (changed) {
+		ieee80211_bss_info_change_notify(sdata, changed);
+		drv_channel_switch_beacon(sdata, &params->chandef);
+	} else {
+		/* if the beacon didn't change, we can finalize immediately */
+		ieee80211_csa_finalize(sdata);
+	}
 
 	return 0;
 }
diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index 3300209..9d4d1e0 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -516,12 +516,6 @@ int ieee80211_ibss_csa_beacon(struct ieee80211_sub_if_data *sdata,
 	if (old_presp)
 		kfree_rcu(old_presp, rcu_head);
 
-	/* it might not send the beacon for a while. send an action frame
-	 * immediately to announce the channel switch.
-	 */
-	if (csa_settings)
-		ieee80211_send_action_csa(sdata, csa_settings);
-
 	return BSS_CHANGED_BEACON;
  out:
 	return ret;
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index bba7897..5c4eca7 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1370,8 +1370,7 @@ void ieee80211_mesh_work(struct ieee80211_sub_if_data *sdata);
 void ieee80211_mesh_rx_queued_mgmt(struct ieee80211_sub_if_data *sdata,
 				   struct sk_buff *skb);
 int ieee80211_mesh_csa_beacon(struct ieee80211_sub_if_data *sdata,
-			      struct cfg80211_csa_settings *csa_settings,
-			      bool csa_action);
+			      struct cfg80211_csa_settings *csa_settings);
 int ieee80211_mesh_finish_csa(struct ieee80211_sub_if_data *sdata);
 
 /* scan/BSS handling */
diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index 6d6c56b..e8f274a 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -1069,8 +1069,7 @@ int ieee80211_mesh_finish_csa(struct ieee80211_sub_if_data *sdata)
 }
 
 int ieee80211_mesh_csa_beacon(struct ieee80211_sub_if_data *sdata,
-			      struct cfg80211_csa_settings *csa_settings,
-			      bool csa_action)
+			      struct cfg80211_csa_settings *csa_settings)
 {
 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
 	struct mesh_csa_settings *tmp_csa_settings;
@@ -1094,9 +1093,6 @@ int ieee80211_mesh_csa_beacon(struct ieee80211_sub_if_data *sdata,
 		return ret;
 	}
 
-	if (csa_action)
-		ieee80211_send_action_csa(sdata, csa_settings);
-
 	return BSS_CHANGED_BEACON;
 }
 
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index c558b24..f324ab7 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2372,15 +2372,6 @@ 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);
-
-	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)
 {
@@ -2409,8 +2400,12 @@ static void ieee80211_update_csa(struct ieee80211_sub_if_data *sdata,
 	if (WARN_ON(counter_offset_beacon >= beacon_data_len))
 		return;
 
-	/* warn if the driver did not check for/react to csa completeness */
-	if (WARN_ON(beacon_data[counter_offset_beacon] == 0))
+	/* Warn if the driver did not check for/react to csa
+	 * completeness.  A beacon with CSA counter set to 0 should
+	 * never occur, because a counter of 1 means switch just
+	 * before the next beacon.
+	 */
+	if (WARN_ON(beacon_data[counter_offset_beacon] == 1))
 		return;
 
 	beacon_data[counter_offset_beacon]--;
@@ -2476,7 +2471,7 @@ bool ieee80211_csa_is_complete(struct ieee80211_vif *vif)
 	if (WARN_ON(counter_beacon > beacon_data_len))
 		goto out;
 
-	if (beacon_data[counter_beacon] == 0)
+	if (beacon_data[counter_beacon] == 1)
 		ret = true;
  out:
 	rcu_read_unlock();
-- 
1.8.4.rc3

Re: [PATCH v4 3/5] mac80211: refactor ieee80211_mesh_process_chanswitch()

[Luca Coelho]

On Wed, 2013-11-13 at 19:47 +0200, Luciano Coelho wrote:
> Refactor ieee80211_mesh_process_chanswitch() to use
> ieee80211_channel_switch() and avoid code duplication.
> 
> Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
> ---

[...]

> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
> index f4af05d..bba7897 100644
> --- a/net/mac80211/ieee80211_i.h
> +++ b/net/mac80211/ieee80211_i.h
> @@ -612,6 +612,7 @@ struct ieee80211_if_mesh {
>  	/* Channel Switching Support */
>  	struct mesh_csa_settings __rcu *csa;
>  	bool chsw_init;
> +	bool csa_repeater;

These two booleans are mutually exclusive, so they should probably be
combined in an enumeration to avoid confusion.

I'll send v5 with this change.

--
Cheers,
Luca.