mac80211: Fix accounting of multicast frames

Since multicast frames are marked as no-ack, using
IEEE80211_TX_STAT_ACK to check if they have been
successfully transmitted by the driver is incorrect
since a driver can choose to ignore transmission status
for no-ack frames. This results in incorrect accounting
for such frames.

To fix this issue, this patch introduces a new flag
that can be used by drivers to indicate error-free
transmission of no-ack frames.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
[add a note about not setting the flag for non-no-ack frames]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 12 insertions, 3 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index b36e60d4c518..b24ef577aed9 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -505,6 +505,11 @@ struct ieee80211_bss_conf {
  * @IEEE80211_TX_CTL_DONTFRAG: Don't fragment this packet even if it
  *      would be fragmented by size (this is optional, only used for
  *      monitor injection).
+ * @IEEE80211_TX_STAT_NOACK_TRANSMITTED: A frame that was marked with
+ *      IEEE80211_TX_CTL_NO_ACK has been successfully transmitted without
+ *      any errors (like issues specific to the driver/HW).
+ *      This flag must not be set for frames that don't request no-ack
+ *      behaviour with IEEE80211_TX_CTL_NO_ACK.
  *
  * Note: If you have to add new flags to the enumeration, then don't
  *       forget to update %IEEE80211_TX_TEMPORARY_FLAGS when necessary.
@@ -540,6 +545,7 @@ enum mac80211_tx_info_flags {
         IEEE80211_TX_STATUS_EOSP                = BIT(28),
         IEEE80211_TX_CTL_USE_MINRATE            = BIT(29),
         IEEE80211_TX_CTL_DONTFRAG               = BIT(30),
+        IEEE80211_TX_STAT_NOACK_TRANSMITTED     = BIT(31),
 };
 
 #define IEEE80211_TX_CTL_STBC_SHIFT             23
diff --git a/net/mac80211/status.c b/net/mac80211/status.c
index bb146f377ee4..d64037c96729 100644
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -664,13 +664,15 @@ void ieee80211_tx_status_noskb(struct ieee80211_hw *hw,
         struct ieee80211_supported_band *sband;
         int retry_count;
         int rates_idx;
-        bool acked;
+        bool acked, noack_success;
 
         rates_idx = ieee80211_tx_get_rates(hw, info, &retry_count);
 
         sband = hw->wiphy->bands[info->band];
 
         acked = !!(info->flags & IEEE80211_TX_STAT_ACK);
+        noack_success = !!(info->flags & IEEE80211_TX_STAT_NOACK_TRANSMITTED);
+
         if (pubsta) {
                 struct sta_info *sta;
 
@@ -696,7 +698,7 @@ void ieee80211_tx_status_noskb(struct ieee80211_hw *hw,
                 rate_control_tx_status_noskb(local, sband, sta, info);
         }
 
-        if (acked) {
+        if (acked || noack_success) {
                     local->dot11TransmittedFrameCount++;
                     if (!pubsta)
                             local->dot11MulticastTransmittedFrameCount++;
@@ -856,7 +858,8 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
          * Fragments are passed to low-level drivers as separate skbs, so these
          * are actually fragments, not frames. Update frame counters only for
          * the first fragment of the frame. */
-        if (info->flags & IEEE80211_TX_STAT_ACK) {
+        if ((info->flags & IEEE80211_TX_STAT_ACK) ||
+            (info->flags & IEEE80211_TX_STAT_NOACK_TRANSMITTED)) {
                 if (ieee80211_is_first_frag(hdr->seq_ctrl)) {
                         local->dot11TransmittedFrameCount++;
                         if (is_multicast_ether_addr(hdr->addr1))