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>
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index b36e60d..b24ef57 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -505,6 +505,11 @@
  * @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 @@
 	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