mac80211: introduce TDLS channel switch ops

Implement the cfg80211 TDLS channel switch ops and introduce new mac80211
ones for low-level drivers.
Verify low-level driver support for the new ops when using the relevant
wiphy feature bit. Also verify the peer supports channel switching before
passing the command down.

Add a new STA flag to track the off-channel state with the TDLS peer and
make sure to cancel the channel-switch if the peer STA is unexpectedly
removed.

Signed-off-by: Arik Nemtsov <arikx.nemtsov@intel.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -2915,6 +2915,16 @@ enum ieee80211_reconfig_type {
  *
  * @get_txpower: get current maximum tx power (in dBm) based on configuration
  *	and hardware limits.
+ *
+ * @tdls_channel_switch: Start channel-switching with a TDLS peer. The driver
+ *	is responsible for continually initiating channel-switching operations
+ *	and returning to the base channel for communication with the AP. The
+ *	driver receives a channel-switch request template and the location of
+ *	the switch-timing IE within the template as part of the invocation.
+ *	The template is valid only within the call, and the driver can
+ *	optionally copy the skb for further re-use.
+ * @tdls_cancel_channel_switch: Stop channel-switching with a TDLS peer. Both
+ *	peers must be on the base channel when the call completes.
  */
 struct ieee80211_ops {
 	void (*tx)(struct ieee80211_hw *hw,
@@ -3126,6 +3136,15 @@ struct ieee80211_ops {
 	u32 (*get_expected_throughput)(struct ieee80211_sta *sta);
 	int (*get_txpower)(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 			   int *dbm);
+
+	int (*tdls_channel_switch)(struct ieee80211_hw *hw,
+				   struct ieee80211_vif *vif,
+				   struct ieee80211_sta *sta, u8 oper_class,
+				   struct cfg80211_chan_def *chandef,
+				   struct sk_buff *skb, u32 ch_sw_tm_ie);
+	void (*tdls_cancel_channel_switch)(struct ieee80211_hw *hw,
+					   struct ieee80211_vif *vif,
+					   struct ieee80211_sta *sta);
 };
 
 /**

net/mac80211/cfg.c

@@ -3752,6 +3752,8 @@ const struct cfg80211_ops mac80211_config_ops = {
 	.set_rekey_data = ieee80211_set_rekey_data,
 	.tdls_oper = ieee80211_tdls_oper,
 	.tdls_mgmt = ieee80211_tdls_mgmt,
+	.tdls_channel_switch = ieee80211_tdls_channel_switch,
+	.tdls_cancel_channel_switch = ieee80211_tdls_cancel_channel_switch,
 	.probe_client = ieee80211_probe_client,
 	.set_noack_map = ieee80211_set_noack_map,
 #ifdef CONFIG_PM

net/mac80211/debugfs_sta.c

@@ -74,7 +74,7 @@ static ssize_t sta_flags_read(struct file *file, char __user *userbuf,
 	test_sta_flag(sta, WLAN_STA_##flg) ? #flg "\n" : ""
 
 	int res = scnprintf(buf, sizeof(buf),
-			    "%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
+			    "%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
 			    TEST(AUTH), TEST(ASSOC), TEST(PS_STA),
 			    TEST(PS_DRIVER), TEST(AUTHORIZED),
 			    TEST(SHORT_PREAMBLE),
@@ -83,10 +83,10 @@ static ssize_t sta_flags_read(struct file *file, char __user *userbuf,
 			    TEST(MFP), TEST(BLOCK_BA), TEST(PSPOLL),
 			    TEST(UAPSD), TEST(SP), TEST(TDLS_PEER),
 			    TEST(TDLS_PEER_AUTH), TEST(TDLS_INITIATOR),
-			    TEST(TDLS_CHAN_SWITCH), TEST(4ADDR_EVENT),
-			    TEST(INSERTED), TEST(RATE_CONTROL),
-			    TEST(TOFFSET_KNOWN), TEST(MPSP_OWNER),
-			    TEST(MPSP_RECIPIENT));
+			    TEST(TDLS_CHAN_SWITCH), TEST(TDLS_OFF_CHANNEL),
+			    TEST(4ADDR_EVENT), TEST(INSERTED),
+			    TEST(RATE_CONTROL), TEST(TOFFSET_KNOWN),
+			    TEST(MPSP_OWNER), TEST(MPSP_RECIPIENT));
 #undef TEST
 	return simple_read_from_buffer(userbuf, count, ppos, buf, res);
 }

net/mac80211/driver-ops.h

@@ -1296,4 +1296,45 @@ static inline int drv_get_txpower(struct ieee80211_local *local,
 	return ret;
 }
 
+static inline int
+drv_tdls_channel_switch(struct ieee80211_local *local,
+			struct ieee80211_sub_if_data *sdata,
+			struct ieee80211_sta *sta, u8 oper_class,
+			struct cfg80211_chan_def *chandef,
+			struct sk_buff *tmpl_skb, u32 ch_sw_tm_ie)
+{
+	int ret;
+
+	might_sleep();
+	if (!check_sdata_in_driver(sdata))
+		return -EIO;
+
+	if (!local->ops->tdls_channel_switch)
+		return -EOPNOTSUPP;
+
+	trace_drv_tdls_channel_switch(local, sdata, sta, oper_class, chandef);
+	ret = local->ops->tdls_channel_switch(&local->hw, &sdata->vif, sta,
+					      oper_class, chandef, tmpl_skb,
+					      ch_sw_tm_ie);
+	trace_drv_return_int(local, ret);
+	return ret;
+}
+
+static inline void
+drv_tdls_cancel_channel_switch(struct ieee80211_local *local,
+			       struct ieee80211_sub_if_data *sdata,
+			       struct ieee80211_sta *sta)
+{
+	might_sleep();
+	if (!check_sdata_in_driver(sdata))
+		return;
+
+	if (!local->ops->tdls_cancel_channel_switch)
+		return;
+
+	trace_drv_tdls_cancel_channel_switch(local, sdata, sta);
+	local->ops->tdls_cancel_channel_switch(&local->hw, &sdata->vif, sta);
+	trace_drv_return_void(local);
+}
+
 #endif /* __MAC80211_DRIVER_OPS */

net/mac80211/ieee80211_i.h

@@ -2007,6 +2007,12 @@ int ieee80211_tdls_mgmt(struct wiphy *wiphy, struct net_device *dev,
 int ieee80211_tdls_oper(struct wiphy *wiphy, struct net_device *dev,
 			const u8 *peer, enum nl80211_tdls_operation oper);
 void ieee80211_tdls_peer_del_work(struct work_struct *wk);
+int ieee80211_tdls_channel_switch(struct wiphy *wiphy, struct net_device *dev,
+				  const u8 *addr, u8 oper_class,
+				  struct cfg80211_chan_def *chandef);
+void ieee80211_tdls_cancel_channel_switch(struct wiphy *wiphy,
+					  struct net_device *dev,
+					  const u8 *addr);
 
 extern const struct ethtool_ops ieee80211_ethtool_ops;
 

net/mac80211/main.c

@@ -764,6 +764,11 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 	     local->hw.offchannel_tx_hw_queue >= local->hw.queues))
 		return -EINVAL;
 
+	if ((hw->wiphy->features & NL80211_FEATURE_TDLS_CHANNEL_SWITCH) &&
+	    (!local->ops->tdls_channel_switch ||
+	     !local->ops->tdls_cancel_channel_switch))
+		return -EOPNOTSUPP;
+
 #ifdef CONFIG_PM
 	if (hw->wiphy->wowlan && (!local->ops->suspend || !local->ops->resume))
 		return -EINVAL;

net/mac80211/sta_info.c

@@ -847,6 +847,15 @@ static int __must_check __sta_info_destroy_part1(struct sta_info *sta)
 	if (WARN_ON(ret))
 		return ret;
 
+	/*
+	 * for TDLS peers, make sure to return to the base channel before
+	 * removal.
+	 */
+	if (test_sta_flag(sta, WLAN_STA_TDLS_OFF_CHANNEL)) {
+		drv_tdls_cancel_channel_switch(local, sdata, &sta->sta);
+		clear_sta_flag(sta, WLAN_STA_TDLS_OFF_CHANNEL);
+	}
+
 	list_del_rcu(&sta->list);
 
 	drv_sta_pre_rcu_remove(local, sta->sdata, sta);

net/mac80211/sta_info.h

@@ -50,6 +50,8 @@
  * @WLAN_STA_TDLS_INITIATOR: We are the initiator of the TDLS link with this
  *	station.
  * @WLAN_STA_TDLS_CHAN_SWITCH: This TDLS peer supports TDLS channel-switching
+ * @WLAN_STA_TDLS_OFF_CHANNEL: The local STA is currently off-channel with this
+ *	TDLS peer
  * @WLAN_STA_UAPSD: Station requested unscheduled SP while driver was
  *	keeping station in power-save mode, reply when the driver
  *	unblocks the station.
@@ -80,6 +82,7 @@ enum ieee80211_sta_info_flags {
 	WLAN_STA_TDLS_PEER_AUTH,
 	WLAN_STA_TDLS_INITIATOR,
 	WLAN_STA_TDLS_CHAN_SWITCH,
+	WLAN_STA_TDLS_OFF_CHANNEL,
 	WLAN_STA_UAPSD,
 	WLAN_STA_SP,
 	WLAN_STA_4ADDR_EVENT,