mac80211: add API to allow filtering frames in BA sessions

If any frames are dropped that are part of a BA session, the reorder
buffer will "indefinitely" (until the timeout) wait for them to come
in (or a BAR moving the window) and won't release frames after them.
This means it isn't possible to filter frames within a BA session in
firmware.

Introduce an API function that allows such filtering. Calling this
function will move the BA window forward to the new SSN, and allows
marking frames after the SSN as having been filtered, so any future
reordering activity will release frames while skipping the holes.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 84 insertions, 0 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 1153871b570f..9fb7074f0280 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -19,6 +19,7 @@
 #include <linux/etherdevice.h>
 #include <linux/rcupdate.h>
 #include <linux/export.h>
+#include <linux/bitops.h>
 #include <net/mac80211.h>
 #include <net/ieee80211_radiotap.h>
 #include <asm/unaligned.h>
@@ -806,6 +807,9 @@ static inline bool ieee80211_rx_reorder_ready(struct tid_ampdu_rx *tid_agg_rx,
 	struct sk_buff *tail = skb_peek_tail(frames);
 	struct ieee80211_rx_status *status;
 
+	if (tid_agg_rx->reorder_buf_filtered & BIT_ULL(index))
+		return true;
+
 	if (!tail)
 		return false;
 
@@ -844,6 +848,7 @@ static void ieee80211_release_reorder_frame(struct ieee80211_sub_if_data *sdata,
 	}
 
 no_frame:
+	tid_agg_rx->reorder_buf_filtered &= ~BIT_ULL(index);
 	tid_agg_rx->head_seq_num = ieee80211_sn_inc(tid_agg_rx->head_seq_num);
 }
 
@@ -3300,6 +3305,85 @@ void ieee80211_release_reorder_timeout(struct sta_info *sta, int tid)
 	ieee80211_rx_handlers(&rx, &frames);
 }
 
+void ieee80211_mark_rx_ba_filtered_frames(struct ieee80211_sta *pubsta, u8 tid,
+					  u16 ssn, u64 filtered,
+					  u16 received_mpdus)
+{
+	struct sta_info *sta;
+	struct tid_ampdu_rx *tid_agg_rx;
+	struct sk_buff_head frames;
+	struct ieee80211_rx_data rx = {
+		/* This is OK -- must be QoS data frame */
+		.security_idx = tid,
+		.seqno_idx = tid,
+	};
+	int i, diff;
+
+	if (WARN_ON(!pubsta || tid >= IEEE80211_NUM_TIDS))
+		return;
+
+	__skb_queue_head_init(&frames);
+
+	sta = container_of(pubsta, struct sta_info, sta);
+
+	rx.sta = sta;
+	rx.sdata = sta->sdata;
+	rx.local = sta->local;
+
+	rcu_read_lock();
+	tid_agg_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
+	if (!tid_agg_rx)
+		goto out;
+
+	spin_lock_bh(&tid_agg_rx->reorder_lock);
+
+	if (received_mpdus >= IEEE80211_SN_MODULO >> 1) {
+		int release;
+
+		/* release all frames in the reorder buffer */
+		release = (tid_agg_rx->head_seq_num + tid_agg_rx->buf_size) %
+			   IEEE80211_SN_MODULO;
+		ieee80211_release_reorder_frames(sta->sdata, tid_agg_rx,
+						 release, &frames);
+		/* update ssn to match received ssn */
+		tid_agg_rx->head_seq_num = ssn;
+	} else {
+		ieee80211_release_reorder_frames(sta->sdata, tid_agg_rx, ssn,
+						 &frames);
+	}
+
+	/* handle the case that received ssn is behind the mac ssn.
+	 * it can be tid_agg_rx->buf_size behind and still be valid */
+	diff = (tid_agg_rx->head_seq_num - ssn) & IEEE80211_SN_MASK;
+	if (diff >= tid_agg_rx->buf_size) {
+		tid_agg_rx->reorder_buf_filtered = 0;
+		goto release;
+	}
+	filtered = filtered >> diff;
+	ssn += diff;
+
+	/* update bitmap */
+	for (i = 0; i < tid_agg_rx->buf_size; i++) {
+		int index = (ssn + i) % tid_agg_rx->buf_size;
+
+		tid_agg_rx->reorder_buf_filtered &= ~BIT_ULL(index);
+		if (filtered & BIT_ULL(i))
+			tid_agg_rx->reorder_buf_filtered |= BIT_ULL(index);
+	}
+
+	/* now process also frames that the filter marking released */
+	ieee80211_sta_reorder_release(sta->sdata, tid_agg_rx, &frames);
+
+release:
+	spin_unlock_bh(&tid_agg_rx->reorder_lock);
+
+	ieee80211_rx_handlers(&rx, &frames);
+
+ out:
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(ieee80211_mark_rx_ba_filtered_frames);
+
 /* main receive path */
 
 static bool ieee80211_accept_frame(struct ieee80211_rx_data *rx)