cfg80211: add channel switch notify event

The firmware may decide to switch channels while already beaconing, e.g.
in response to a cfg80211 connect request on a different vif. Add this
event to notify userspace when an AP or GO interface has successfully
migrated to a new channel, so it can update its configuration
accordingly.
Signed-off-by: Thomas Pedersen <c_tpeder@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/nl80211.h

@@ -548,6 +548,11 @@
  * @NL80211_CMD_SET_NOACK_MAP: sets a bitmap for the individual TIDs whether
  *      No Acknowledgement Policy should be applied.
  *
+ * @NL80211_CMD_CH_SWITCH_NOTIFY: An AP or GO may decide to switch channels
+ *	independently of the userspace SME, send this event indicating
+ *	%NL80211_ATTR_IFINDEX is now on %NL80211_ATTR_WIPHY_FREQ with
+ *	%NL80211_ATTR_WIPHY_CHANNEL_TYPE.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -689,6 +694,8 @@ enum nl80211_commands {
 
 	NL80211_CMD_SET_NOACK_MAP,
 
+	NL80211_CMD_CH_SWITCH_NOTIFY,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */

include/net/cfg80211.h

@@ -3354,6 +3354,17 @@ int cfg80211_can_beacon_sec_chan(struct wiphy *wiphy,
 				 struct ieee80211_channel *chan,
 				 enum nl80211_channel_type channel_type);
 
+/*
+ * cfg80211_ch_switch_notify - update wdev channel and notify userspace
+ * @dev: the device which switched channels
+ * @freq: new channel frequency (in MHz)
+ * @type: channel type
+ *
+ * Acquires wdev_lock, so must only be called from sleepable driver context!
+ */
+void cfg80211_ch_switch_notify(struct net_device *dev, int freq,
+			       enum nl80211_channel_type type);
+
 /*
  * cfg80211_calculate_bitrate - calculate actual bitrate (in 100Kbps units)
  * @rate: given rate_info to calculate bitrate from

net/wireless/mlme.c

@@ -930,6 +930,33 @@ void cfg80211_pmksa_candidate_notify(struct net_device *dev, int index,
 }
 EXPORT_SYMBOL(cfg80211_pmksa_candidate_notify);
 
+void cfg80211_ch_switch_notify(struct net_device *dev, int freq,
+			       enum nl80211_channel_type type)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct wiphy *wiphy = wdev->wiphy;
+	struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
+	struct ieee80211_channel *chan;
+
+	wdev_lock(wdev);
+
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_AP &&
+		    wdev->iftype != NL80211_IFTYPE_P2P_GO))
+		goto out;
+
+	chan = rdev_freq_to_chan(rdev, freq, type);
+	if (WARN_ON(!chan))
+		goto out;
+
+	wdev->channel = chan;
+
+	nl80211_ch_switch_notify(rdev, dev, freq, type, GFP_KERNEL);
+out:
+	wdev_unlock(wdev);
+	return;
+}
+EXPORT_SYMBOL(cfg80211_ch_switch_notify);
+
 bool cfg80211_rx_spurious_frame(struct net_device *dev,
 				const u8 *addr, gfp_t gfp)
 {

net/wireless/nl80211.c

@@ -7922,6 +7922,38 @@ void nl80211_pmksa_candidate_notify(struct cfg80211_registered_device *rdev,
 	nlmsg_free(msg);
 }
 
+void nl80211_ch_switch_notify(struct cfg80211_registered_device *rdev,
+			      struct net_device *netdev, int freq,
+			      enum nl80211_channel_type type, gfp_t gfp)
+{
+	struct sk_buff *msg;
+	void *hdr;
+
+	msg = nlmsg_new(NLMSG_GOODSIZE, gfp);
+	if (!msg)
+		return;
+
+	hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_CH_SWITCH_NOTIFY);
+	if (!hdr) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, netdev->ifindex);
+	NLA_PUT_U32(msg, NL80211_ATTR_WIPHY_FREQ, freq);
+	NLA_PUT_U32(msg, NL80211_ATTR_WIPHY_CHANNEL_TYPE, type);
+
+	genlmsg_end(msg, hdr);
+
+	genlmsg_multicast_netns(wiphy_net(&rdev->wiphy), msg, 0,
+				nl80211_mlme_mcgrp.id, gfp);
+	return;
+
+ nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	nlmsg_free(msg);
+}
+
 void
 nl80211_send_cqm_pktloss_notify(struct cfg80211_registered_device *rdev,
 				struct net_device *netdev, const u8 *peer,

net/wireless/nl80211.h

@@ -118,6 +118,10 @@ void nl80211_pmksa_candidate_notify(struct cfg80211_registered_device *rdev,
 				    struct net_device *netdev, int index,
 				    const u8 *bssid, bool preauth, gfp_t gfp);
 
+void nl80211_ch_switch_notify(struct cfg80211_registered_device *rdev,
+			      struct net_device *dev, int freq,
+			      enum nl80211_channel_type type, gfp_t gfp);
+
 bool nl80211_unexpected_frame(struct net_device *dev,
 			      const u8 *addr, gfp_t gfp);
 bool nl80211_unexpected_4addr_frame(struct net_device *dev,