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

1 files changed, 11 insertions, 4 deletions

diff --git a/sys/net80211/ieee80211_ht.c b/sys/net80211/ieee80211_ht.c
index 23a765f..d403220 100644
--- a/sys/net80211/ieee80211_ht.c
+++ b/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);
 }
 
 /*