mac80211: fix duration calculation for QoS NOACK frames

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 205fdcb70fff..a5ff02fbda8c 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -151,11 +151,15 @@ static __le16 ieee80211_duration(struct ieee80211_tx_data *tx,
                 rate = mrate;
         }
 
-        /* Time needed to transmit ACK
-         * (10 bytes + 4-byte FCS = 112 bits) plus SIFS; rounded up
-         * to closest integer */
-
-        dur = ieee80211_frame_duration(local, 10, rate, erp,
+        /* Don't calculate ACKs for QoS Frames with NoAck Policy set */
+        if (ieee80211_is_data_qos(hdr->frame_control) &&
+            *(ieee80211_get_qos_ctl(hdr)) | IEEE80211_QOS_CTL_ACK_POLICY_NOACK)
+                dur = 0;
+        else
+                /* Time needed to transmit ACK
+                 * (10 bytes + 4-byte FCS = 112 bits) plus SIFS; rounded up
+                 * to closest integer */
+                dur = ieee80211_frame_duration(local, 10, rate, erp,
                                 tx->sdata->vif.bss_conf.use_short_preamble);
 
         if (next_frag_len) {