iwlwifi: mvm: add reorder timeout per frame

Add a timer in order to release expired frames from the
reorder buffer.
This is needed since some APs do not retransmit frames
to fill in the reorder holes and in TCP it results with
a complete stall of traffic.

This has a few side effects on the general design:

The nssn may not reflect the the head of the reorder buffer.
This situation is valid, and packets with SN lower than the
reorder buffer head will be dropped.

Another side effect is that since the reorder timer might expire
we need to lock the reorder buffer.
This however is fine since the locking is only inside a
single reorder buffer between RX path and reorder timeout and
there is no outside contention.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

1 files changed, 22 insertions, 1 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/sta.c b/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
index 2b839114a60f..e7f1da56d82d 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
@@ -1189,8 +1189,11 @@ static void iwl_mvm_free_reorder(struct iwl_mvm *mvm,
 		struct iwl_mvm_reorder_buffer *reorder_buf =
 			&data->reorder_buf[i];
 
-		if (likely(!reorder_buf->num_stored))
+		spin_lock_bh(&reorder_buf->lock);
+		if (likely(!reorder_buf->num_stored)) {
+			spin_unlock_bh(&reorder_buf->lock);
 			continue;
+		}
 
 		/*
 		 * This shouldn't happen in regular DELBA since the internal
@@ -1201,6 +1204,17 @@ static void iwl_mvm_free_reorder(struct iwl_mvm *mvm,
 
 		for (j = 0; j < reorder_buf->buf_size; j++)
 			__skb_queue_purge(&reorder_buf->entries[j]);
+		/*
+		 * Prevent timer re-arm. This prevents a very far fetched case
+		 * where we timed out on the notification. There may be prior
+		 * RX frames pending in the RX queue before the notification
+		 * that might get processed between now and the actual deletion
+		 * and we would re-arm the timer although we are deleting the
+		 * reorder buffer.
+		 */
+		reorder_buf->removed = true;
+		spin_unlock_bh(&reorder_buf->lock);
+		del_timer_sync(&reorder_buf->reorder_timer);
 	}
 }
 
@@ -1219,6 +1233,13 @@ static void iwl_mvm_init_reorder_buffer(struct iwl_mvm *mvm,
 		reorder_buf->num_stored = 0;
 		reorder_buf->head_sn = ssn;
 		reorder_buf->buf_size = buf_size;
+		/* rx reorder timer */
+		reorder_buf->reorder_timer.function =
+			iwl_mvm_reorder_timer_expired;
+		reorder_buf->reorder_timer.data = (unsigned long)reorder_buf;
+		init_timer(&reorder_buf->reorder_timer);
+		spin_lock_init(&reorder_buf->lock);
+		reorder_buf->mvm = mvm;
 		reorder_buf->queue = i;
 		reorder_buf->sta_id = sta_id;
 		for (j = 0; j < reorder_buf->buf_size; j++)