mac80211: track receiver's aggregation reorder buffer size

The aggregation code currently doesn't implement the
buffer size negotiation. It will always request a max
buffer size (which is fine, if a little pointless, as
the mac80211 code doesn't know and might just use 0
instead), but if the peer requests a smaller size it
isn't possible to honour this request.

In order to fix this, look at the buffer size in the
addBA response frame, keep track of it and pass it to
the driver in the ampdu_action callback when called
with the IEEE80211_AMPDU_TX_OPERATIONAL action. That
way the driver can limit the number of subframes in
aggregates appropriately.

Note that this doesn't fix any drivers apart from the
addition of the new argument -- they all need to be
updated separately to use this variable!

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 17 insertions, 3 deletions

diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index 9cc472c6a6a5..42f7c9007331 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -190,7 +190,7 @@ int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,
 
 	ret = drv_ampdu_action(local, sta->sdata,
 			       IEEE80211_AMPDU_TX_STOP,
-			       &sta->sta, tid, NULL);
+			       &sta->sta, tid, NULL, 0);
 
 	/* HW shall not deny going back to legacy */
 	if (WARN_ON(ret)) {
@@ -311,7 +311,7 @@ void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid)
 	start_seq_num = sta->tid_seq[tid] >> 4;
 
 	ret = drv_ampdu_action(local, sdata, IEEE80211_AMPDU_TX_START,
-			       &sta->sta, tid, &start_seq_num);
+			       &sta->sta, tid, &start_seq_num, 0);
 	if (ret) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		printk(KERN_DEBUG "BA request denied - HW unavailable for"
@@ -487,7 +487,8 @@ static void ieee80211_agg_tx_operational(struct ieee80211_local *local,
 
 	drv_ampdu_action(local, sta->sdata,
 			 IEEE80211_AMPDU_TX_OPERATIONAL,
-			 &sta->sta, tid, NULL);
+			 &sta->sta, tid, NULL,
+			 sta->ampdu_mlme.tid_tx[tid]->buf_size);
 
 	/*
 	 * synchronize with TX path, while splicing the TX path
@@ -742,9 +743,11 @@ void ieee80211_process_addba_resp(struct ieee80211_local *local,
 {
 	struct tid_ampdu_tx *tid_tx;
 	u16 capab, tid;
+	u8 buf_size;
 
 	capab = le16_to_cpu(mgmt->u.action.u.addba_resp.capab);
 	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
+	buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;
 
 	mutex_lock(&sta->ampdu_mlme.mtx);
 
@@ -767,12 +770,23 @@ void ieee80211_process_addba_resp(struct ieee80211_local *local,
 
 	if (le16_to_cpu(mgmt->u.action.u.addba_resp.status)
 			== WLAN_STATUS_SUCCESS) {
+		/*
+		 * IEEE 802.11-2007 7.3.1.14:
+		 * In an ADDBA Response frame, when the Status Code field
+		 * is set to 0, the Buffer Size subfield is set to a value
+		 * of at least 1.
+		 */
+		if (!buf_size)
+			goto out;
+
 		if (test_and_set_bit(HT_AGG_STATE_RESPONSE_RECEIVED,
 				     &tid_tx->state)) {
 			/* ignore duplicate response */
 			goto out;
 		}
 
+		tid_tx->buf_size = buf_size;
+
 		if (test_bit(HT_AGG_STATE_DRV_READY, &tid_tx->state))
 			ieee80211_agg_tx_operational(local, sta, tid);