Create a new task to handle 802.11n channel width changes.

Currently, a channel width change updates the 802.11n HT info data in
net80211 but it doesn't trigger any device changes.  So the device
driver may decide that HT40 frames can be transmitted but the last
device channel set only had HT20 set.

Now, a task is scheduled so a hardware reset or change isn't done
during any active ongoing RX. It also means that it's serialised
with the other task operations (eg channel change.)

This isn't the final incantation of this work, see below.

For now, any unmodified drivers will simply receive a channel
change log entry.  A subsequent patch to ath(4) will introduce
some basic channel change handling (by resetting the NIC.)
Other NICs may need to update their rate control information.

TODO:

* There's still a small window at the present moment where the
  channel width has been updated but the task hasn't been fired.
  The final version of this should likely pass in a channel width
  field to the driver and let the driver atomically do whatever
  it needs to before changing the channel.

PR:		kern/166286

sys/net80211/ieee80211.c

@@ -256,6 +256,13 @@ null_input(struct ifnet *ifp, struct mbuf *m)
 	m_freem(m);
 }
 
+static void
+null_update_chw(struct ieee80211com *ic)
+{
+
+	if_printf(ic->ic_ifp, "%s: need callback\n", __func__);
+}
+
 /*
  * Attach/setup the common net80211 state.  Called by
  * the driver on attach to prior to creating any vap's.
@@ -287,6 +294,7 @@ ieee80211_ifattach(struct ieee80211com *ic,
 
 	ic->ic_update_mcast = null_update_mcast;
 	ic->ic_update_promisc = null_update_promisc;
+	ic->ic_update_chw = null_update_chw;
 
 	ic->ic_hash_key = arc4random();
 	ic->ic_bintval = IEEE80211_BINTVAL_DEFAULT;

sys/net80211/ieee80211_ht.c

@@ -1428,12 +1428,13 @@ ieee80211_parse_htinfo(struct ieee80211_node *ni, const uint8_t *ie)
  * required channel change is done (e.g. in sta mode when
  * parsing the contents of a beacon frame).
  */
-static void
+static int
 htinfo_update_chw(struct ieee80211_node *ni, int htflags)
 {
 	struct ieee80211com *ic = ni->ni_ic;
 	struct ieee80211_channel *c;
 	int chanflags;
+	int ret = 0;
 
 	chanflags = (ni->ni_chan->ic_flags &~ IEEE80211_CHAN_HT) | htflags;
 	if (chanflags != ni->ni_chan->ic_flags) {
@@ -1460,11 +1461,13 @@ htinfo_update_chw(struct ieee80211_node *ni, int htflags)
 			    IEEE80211_IS_CHAN_HT40(c) ? 40 : 20,
 			    c->ic_freq, c->ic_flags);
 			ni->ni_chan = c;
+			ret = 1;
 		}
 		/* NB: caller responsible for forcing any channel change */
 	}
 	/* update node's tx channel width */
 	ni->ni_chw = IEEE80211_IS_CHAN_HT40(ni->ni_chan)? 40 : 20;
+	return (ret);
 }
 
 /*
@@ -1515,13 +1518,14 @@ htcap_update_shortgi(struct ieee80211_node *ni)
  * Parse and update HT-related state extracted from
  * the HT cap and info ie's.
  */
-void
+int
 ieee80211_ht_updateparams(struct ieee80211_node *ni,
 	const uint8_t *htcapie, const uint8_t *htinfoie)
 {
 	struct ieee80211vap *vap = ni->ni_vap;
 	const struct ieee80211_ie_htinfo *htinfo;
 	int htflags;
+	int ret = 0;
 
 	ieee80211_parse_htcap(ni, htcapie);
 	if (vap->iv_htcaps & IEEE80211_HTCAP_SMPS)
@@ -1543,13 +1547,16 @@ ieee80211_ht_updateparams(struct ieee80211_node *ni,
 		else if (ni->ni_ht2ndchan == IEEE80211_HTINFO_2NDCHAN_BELOW)
 			htflags = IEEE80211_CHAN_HT40D;
 	}
-	htinfo_update_chw(ni, htflags);
+	if (htinfo_update_chw(ni, htflags))
+		ret = 1;
 
 	if ((htinfo->hi_byte1 & IEEE80211_HTINFO_RIFSMODE_PERM) &&
 	    (vap->iv_flags_ht & IEEE80211_FHT_RIFS))
 		ni->ni_flags |= IEEE80211_NODE_RIFS;
 	else
 		ni->ni_flags &= ~IEEE80211_NODE_RIFS;
+
+	return (ret);
 }
 
 /*
@@ -1578,7 +1585,7 @@ ieee80211_ht_updatehtcap(struct ieee80211_node *ni, const uint8_t *htcapie)
 		else if (IEEE80211_IS_CHAN_HT40D(vap->iv_bss->ni_chan))
 			htflags = IEEE80211_CHAN_HT40D;
 	}
-	htinfo_update_chw(ni, htflags);
+	(void) htinfo_update_chw(ni, htflags);
 }
 
 /*

sys/net80211/ieee80211_ht.h

@@ -184,7 +184,7 @@ void	ieee80211_htprot_update(struct ieee80211com *, int protmode);
 void	ieee80211_ht_timeout(struct ieee80211com *);
 void	ieee80211_parse_htcap(struct ieee80211_node *, const uint8_t *);
 void	ieee80211_parse_htinfo(struct ieee80211_node *, const uint8_t *);
-void	ieee80211_ht_updateparams(struct ieee80211_node *, const uint8_t *,
+int	ieee80211_ht_updateparams(struct ieee80211_node *, const uint8_t *,
 		const uint8_t *);
 void	ieee80211_ht_updatehtcap(struct ieee80211_node *, const uint8_t *);
 int	ieee80211_ampdu_request(struct ieee80211_node *,

sys/net80211/ieee80211_node.c

@@ -685,6 +685,14 @@ ieee80211_setcurchan(struct ieee80211com *ic, struct ieee80211_channel *c)
 	ieee80211_runtask(ic, &ic->ic_chan_task);
 }
 
+void
+ieee80211_update_chw(struct ieee80211com *ic)
+{
+
+	ieee80211_setupcurchan(ic, ic->ic_curchan);
+	ieee80211_runtask(ic, &ic->ic_chw_task);
+}
+
 /*
  * Join the specified IBSS/BSS network.  The node is assumed to
  * be passed in with a held reference.

sys/net80211/ieee80211_node.h

@@ -324,6 +324,7 @@ void	ieee80211_sync_curchan(struct ieee80211com *);
 void	ieee80211_setupcurchan(struct ieee80211com *,
 	    struct ieee80211_channel *);
 void	ieee80211_setcurchan(struct ieee80211com *, struct ieee80211_channel *);
+void	ieee80211_update_chw(struct ieee80211com *);
 int	ieee80211_ibss_merge(struct ieee80211_node *);
 struct ieee80211_scan_entry;
 int	ieee80211_sta_join(struct ieee80211vap *, struct ieee80211_channel *,

sys/net80211/ieee80211_proto.c

@@ -105,6 +105,7 @@ static void parent_updown(void *, int);
 static void update_mcast(void *, int);
 static void update_promisc(void *, int);
 static void update_channel(void *, int);
+static void update_chw(void *, int);
 static void ieee80211_newstate_cb(void *, int);
 static int ieee80211_new_state_locked(struct ieee80211vap *,
 	enum ieee80211_state, int);
@@ -144,6 +145,7 @@ ieee80211_proto_attach(struct ieee80211com *ic)
 	TASK_INIT(&ic->ic_promisc_task, 0, update_promisc, ic);
 	TASK_INIT(&ic->ic_chan_task, 0, update_channel, ic);
 	TASK_INIT(&ic->ic_bmiss_task, 0, beacon_miss, ic);
+	TASK_INIT(&ic->ic_chw_task, 0, update_chw, ic);
 
 	ic->ic_wme.wme_hipri_switch_hysteresis =
 		AGGRESSIVE_MODE_SWITCH_HYSTERESIS;
@@ -1147,6 +1149,17 @@ update_channel(void *arg, int npending)
 	ieee80211_radiotap_chan_change(ic);
 }
 
+static void
+update_chw(void *arg, int npending)
+{
+	struct ieee80211com *ic = arg;
+
+	/*
+	 * XXX should we defer the channel width _config_ update until now?
+	 */
+	ic->ic_update_chw(ic);
+}
+
 /*
  * Block until the parent is in a known state.  This is
  * used after any operations that dispatch a task (e.g.
@@ -1161,6 +1174,7 @@ ieee80211_waitfor_parent(struct ieee80211com *ic)
 	ieee80211_draintask(ic, &ic->ic_promisc_task);
 	ieee80211_draintask(ic, &ic->ic_chan_task);
 	ieee80211_draintask(ic, &ic->ic_bmiss_task);
+	ieee80211_draintask(ic, &ic->ic_chw_task);
 	taskqueue_unblock(ic->ic_tq);
 }
 

sys/net80211/ieee80211_sta.c

@@ -1285,6 +1285,7 @@ sta_recv_mgmt(struct ieee80211_node *ni, struct mbuf *m0,
 	uint8_t *frm, *efrm;
 	uint8_t *rates, *xrates, *wme, *htcap, *htinfo;
 	uint8_t rate;
+	int ht_state_change = 0;
 
 	wh = mtod(m0, struct ieee80211_frame *);
 	frm = (uint8_t *)&wh[1];
@@ -1372,9 +1373,10 @@ sta_recv_mgmt(struct ieee80211_node *ni, struct mbuf *m0,
 #endif
 			if (scan.htcap != NULL && scan.htinfo != NULL &&
 			    (vap->iv_flags_ht & IEEE80211_FHT_HT)) {
-				ieee80211_ht_updateparams(ni,
-				    scan.htcap, scan.htinfo);
 				/* XXX state changes? */
+				if (ieee80211_ht_updateparams(ni,
+				    scan.htcap, scan.htinfo))
+					ht_state_change = 1;
 			}
 			if (scan.quiet)
 				ic->ic_set_quiet(ni, scan.quiet);
@@ -1441,6 +1443,13 @@ sta_recv_mgmt(struct ieee80211_node *ni, struct mbuf *m0,
 #endif
 				ieee80211_bg_scan(vap, 0);
 			}
+
+			/*
+			 * If we've had a channel width change (eg HT20<->HT40)
+			 * then schedule a delayed driver notification.
+			 */
+			if (ht_state_change)
+				ieee80211_update_chw(ic);
 			return;
 		}
 		/*

sys/net80211/ieee80211_var.h

@@ -130,6 +130,7 @@ struct ieee80211com {
 	struct task		ic_mcast_task;	/* deferred mcast update */
 	struct task		ic_chan_task;	/* deferred channel change */
 	struct task		ic_bmiss_task;	/* deferred beacon miss hndlr */
+	struct task		ic_chw_task;	/* deferred HT CHW update */
 
 	uint32_t		ic_flags;	/* state flags */
 	uint32_t		ic_flags_ext;	/* extended state flags */
@@ -322,6 +323,10 @@ struct ieee80211com {
 				    int batimeout, int baseqctl);
 	void			(*ic_ampdu_rx_stop)(struct ieee80211_node *,
 				    struct ieee80211_rx_ampdu *);
+
+	/* The channel width has changed (20<->2040) */
+	void			(*ic_update_chw)(struct ieee80211com *);
+
 	uint64_t		ic_spare[7];
 };