mac80211: add feature flag to enable resizing of outgoing frames for encryption

index 58d719d..c04ac04 100644
@@ -1270,8 +1270,11 @@ struct ieee80211_vif *wdev_to_ieee80211_vif(struct wireless_dev *wdev);
  *
  * @IEEE80211_KEY_FLAG_GENERATE_IV: This flag should be set by the
  *	driver to indicate that it requires IV generation for this
- *	particular key. Setting this flag does not necessarily mean that SKBs
- *	will have sufficient tailroom for ICV or MIC.
+ *	particular key. Setting this flag does not mean that SKBs will
+ *	have sufficient tailroom for ICV or MIC. If additional tailroom
+ *	tailroom needs to be reserved for the ICV or MIC, the driver
+ *	should also set the hardware feature flag:
+ *      %IEEE80211_HW_TAILROOM_CRYPTO.
  * @IEEE80211_KEY_FLAG_GENERATE_MMIC: This flag should be set by
  *	the driver for a TKIP key if it requires Michael MIC
  *	generation in software.

@@ -1583,6 +1586,10 @@ struct ieee80211_tx_control {
  * @IEEE80211_HW_MFP_CAPABLE:
  *	Hardware supports management frame protection (MFP, IEEE 802.11w).
  *
+ * @IEEE80211_HW_TAILROOM_CRYPTO: The driver would like to have sufficient
+ *	tailroom for ICV or MIC for outgoing frames in order to perform
+ *	hardware encryption without any additional resizing overhead.
+ *
  * @IEEE80211_HW_SUPPORTS_UAPSD:
  *	Hardware supports Unscheduled Automatic Power Save Delivery
  *	(U-APSD) in managed mode. The mode is configured with

@@ -1673,7 +1680,7 @@ enum ieee80211_hw_flags {
 	IEEE80211_HW_MFP_CAPABLE			= 1<<13,
 	IEEE80211_HW_WANT_MONITOR_VIF			= 1<<14,
 	IEEE80211_HW_NO_AUTO_VIF			= 1<<15,
-	/* free slot */
+	IEEE80211_HW_TAILROOM_CRYPTO			= 1<<16,
 	IEEE80211_HW_SUPPORTS_UAPSD			= 1<<17,
 	IEEE80211_HW_REPORTS_TX_ACK_STATUS		= 1<<18,
 	IEEE80211_HW_CONNECTION_MONITOR			= 1<<19,

index 0bb7038..c3e9a9a 100644
@@ -140,7 +140,8 @@ static int ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
 	if (!ret) {
 		key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
 
-		if (!(key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC))
+		if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
+		      (key->local->hw.flags & IEEE80211_HW_TAILROOM_CRYPTO)))
 			sdata->crypto_tx_tailroom_needed_cnt--;
 
 		WARN_ON((key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE) &&

@@ -188,7 +189,8 @@ static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
 	sta = key->sta;
 	sdata = key->sdata;
 
-	if (!(key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC))
+	if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
+	      (key->local->hw.flags & IEEE80211_HW_TAILROOM_CRYPTO)))
 		increment_tailroom_need_count(sdata);
 
 	ret = drv_set_key(key->local, DISABLE_KEY, sdata,

@@ -884,7 +886,8 @@ void ieee80211_remove_key(struct ieee80211_key_conf *keyconf)
 	if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 		key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
 
-		if (!(key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC))
+		if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
+		      (key->local->hw.flags & IEEE80211_HW_TAILROOM_CRYPTO)))
 			increment_tailroom_need_count(key->sdata);
 	}