mac80211: synchronously reserve TID per station

In TDLS (e.g., TDLS off-channel) there is a requirement for
some drivers to supply an unused TID between the AP and the
device to the FW, to allow sending PTI requests and to allow
the FW to aggregate on a specific TID for better throughput.

To ensure that the allocated TID is indeed unused, this patch
introduces an API for blocking the driver from TXing on that
TID.

Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index 9242c60048cf..a360c15cc978 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -509,6 +509,10 @@ int ieee80211_start_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid,
         struct tid_ampdu_tx *tid_tx;
         int ret = 0;
 
+        if (WARN(sta->reserved_tid == tid,
+                 "Requested to start BA session on reserved tid=%d", tid))
+                return -EINVAL;
+
         trace_api_start_tx_ba_session(pubsta, tid);
 
         if (WARN_ON_ONCE(!local->ops->ampdu_action))
@@ -765,6 +769,9 @@ int ieee80211_stop_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid)
                 goto unlock;
         }
 
+        WARN(sta->reserved_tid == tid,
+             "Requested to stop BA session on reserved tid=%d", tid);
+
         if (test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
                 /* already in progress stopping it */
                 ret = 0;