mac80211: improve rate handling

Some code currently assumes that there's a valid
rate pointer even in the HT case, but there can't
be. To reduce reliance on that, remove the rate
pointer from the RX data struct and pass it where
it's needed.

Also, for now, in radiotap announce HT frames as
having a DYN channel type, and remove their rate
from cooked monitor radiotap completely (it isn't
present in the regular monitor radiotap either.)

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 904aaea..e0cb335 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -163,6 +163,9 @@
 	if (status->band == IEEE80211_BAND_5GHZ)
 		put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_5GHZ,
 				   pos);
+	else if (status->flag & RX_FLAG_HT)
+		put_unaligned_le16(IEEE80211_CHAN_DYN | IEEE80211_CHAN_2GHZ,
+				   pos);
 	else if (rate->flags & IEEE80211_RATE_ERP_G)
 		put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_2GHZ,
 				   pos);
@@ -1845,14 +1848,15 @@
 }
 
 /* TODO: use IEEE80211_RX_FRAGMENTED */
-static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx)
+static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx,
+					struct ieee80211_rate *rate)
 {
 	struct ieee80211_sub_if_data *sdata;
 	struct ieee80211_local *local = rx->local;
 	struct ieee80211_rtap_hdr {
 		struct ieee80211_radiotap_header hdr;
 		u8 flags;
-		u8 rate;
+		u8 rate_or_pad;
 		__le16 chan_freq;
 		__le16 chan_flags;
 	} __attribute__ ((packed)) *rthdr;
@@ -1872,10 +1876,13 @@
 	rthdr->hdr.it_len = cpu_to_le16(sizeof(*rthdr));
 	rthdr->hdr.it_present =
 		cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
-			    (1 << IEEE80211_RADIOTAP_RATE) |
 			    (1 << IEEE80211_RADIOTAP_CHANNEL));
 
-	rthdr->rate = rx->rate->bitrate / 5;
+	if (rate) {
+		rthdr->rate_or_pad = rate->bitrate / 5;
+		rthdr->hdr.it_present |=
+			cpu_to_le32(1 << IEEE80211_RADIOTAP_RATE);
+	}
 	rthdr->chan_freq = cpu_to_le16(status->freq);
 
 	if (status->band == IEEE80211_BAND_5GHZ)
@@ -1928,7 +1935,8 @@
 
 static void ieee80211_invoke_rx_handlers(struct ieee80211_sub_if_data *sdata,
 					 struct ieee80211_rx_data *rx,
-					 struct sk_buff *skb)
+					 struct sk_buff *skb,
+					 struct ieee80211_rate *rate)
 {
 	ieee80211_rx_result res = RX_DROP_MONITOR;
 
@@ -1972,7 +1980,7 @@
 			rx->sta->rx_dropped++;
 		/* fall through */
 	case RX_CONTINUE:
-		ieee80211_rx_cooked_monitor(rx);
+		ieee80211_rx_cooked_monitor(rx, rate);
 		break;
 	case RX_DROP_UNUSABLE:
 		I802_DEBUG_INC(sdata->local->rx_handlers_drop);
@@ -2095,7 +2103,6 @@
 	memset(&rx, 0, sizeof(rx));
 	rx.skb = skb;
 	rx.local = local;
-	rx.rate = rate;
 
 	if (ieee80211_is_data(hdr->frame_control) || ieee80211_is_mgmt(hdr->frame_control))
 		local->dot11ReceivedFragmentCount++;
@@ -2167,11 +2174,11 @@
 				       prev->dev->name);
 			continue;
 		}
-		ieee80211_invoke_rx_handlers(prev, &rx, skb_new);
+		ieee80211_invoke_rx_handlers(prev, &rx, skb_new, rate);
 		prev = sdata;
 	}
 	if (prev)
-		ieee80211_invoke_rx_handlers(prev, &rx, skb);
+		ieee80211_invoke_rx_handlers(prev, &rx, skb, rate);
 	else
 		dev_kfree_skb(skb);
 }
@@ -2200,7 +2207,7 @@
 					    int index)
 {
 	struct ieee80211_supported_band *sband;
-	struct ieee80211_rate *rate;
+	struct ieee80211_rate *rate = NULL;
 	struct sk_buff *skb = tid_agg_rx->reorder_buf[index];
 	struct ieee80211_rx_status *status;
 
@@ -2211,9 +2218,7 @@
 
 	/* release the reordered frames to stack */
 	sband = hw->wiphy->bands[status->band];
-	if (status->flag & RX_FLAG_HT)
-		rate = sband->bitrates; /* TODO: HT rates */
-	else
+	if (!(status->flag & RX_FLAG_HT))
 		rate = &sband->bitrates[status->rate_idx];
 	__ieee80211_rx_handle_packet(hw, skb, rate);
 	tid_agg_rx->stored_mpdu_num--;
@@ -2460,10 +2465,6 @@
 			 status->rate_idx,
 			 status->rate_idx))
 			goto drop;
-		/* HT rates are not in the table - use the highest legacy rate
-		 * for now since other parts of mac80211 may not yet be fully
-		 * MCS aware. */
-		rate = &sband->bitrates[sband->n_bitrates - 1];
 	} else {
 		if (WARN_ON(status->rate_idx < 0 ||
 			    status->rate_idx >= sband->n_bitrates))