Revert "mac80211: Skip tailroom reservation for full HW-crypto devices"

This reverts commit aac6af5534.

Conflicts:

	net/mac80211/key.c

That commit has a race that causes a warning, as documented in the thread
here:

	http://marc.info/?l=linux-wireless&m=130717684914101&w=2

Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/ieee80211_i.h

@@ -775,9 +775,6 @@ struct ieee80211_local {
 
 	int tx_headroom; /* required headroom for hardware/radiotap */
 
-	/* count for keys needing tailroom space allocation */
-	int crypto_tx_tailroom_needed_cnt;
-
 	/* Tasklet and skb queue to process calls from IRQ mode. All frames
 	 * added to skb_queue will be processed, but frames in
 	 * skb_queue_unreliable may be dropped if the total length of these

net/mac80211/key.c

@@ -101,11 +101,6 @@ 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) ||
-		      (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)))
-			key->local->crypto_tx_tailroom_needed_cnt--;
-
 		return 0;
 	}
 
@@ -161,10 +156,6 @@ static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
 			  key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
 
 	key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
-
-	if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
-	      (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)))
-		key->local->crypto_tx_tailroom_needed_cnt++;
 }
 
 void ieee80211_key_removed(struct ieee80211_key_conf *key_conf)
@@ -403,10 +394,8 @@ static void __ieee80211_key_destroy(struct ieee80211_key *key)
 		ieee80211_aes_key_free(key->u.ccmp.tfm);
 	if (key->conf.cipher == WLAN_CIPHER_SUITE_AES_CMAC)
 		ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
-	if (key->local) {
+	if (key->local)
 		ieee80211_debugfs_key_remove(key);
-		key->local->crypto_tx_tailroom_needed_cnt--;
-	}
 
 	kfree(key);
 }
@@ -468,8 +457,6 @@ int ieee80211_key_link(struct ieee80211_key *key,
 
 	ieee80211_debugfs_key_add(key);
 
-	key->local->crypto_tx_tailroom_needed_cnt++;
-
 	ret = ieee80211_key_enable_hw_accel(key);
 
 	mutex_unlock(&sdata->local->key_mtx);
@@ -511,12 +498,8 @@ void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
 
 	mutex_lock(&sdata->local->key_mtx);
 
-	sdata->local->crypto_tx_tailroom_needed_cnt = 0;
-
-	list_for_each_entry(key, &sdata->key_list, list) {
-		sdata->local->crypto_tx_tailroom_needed_cnt++;
+	list_for_each_entry(key, &sdata->key_list, list)
 		ieee80211_key_enable_hw_accel(key);
-	}
 
 	mutex_unlock(&sdata->local->key_mtx);
 }

net/mac80211/tx.c

@@ -1480,7 +1480,12 @@ static int ieee80211_skb_resize(struct ieee80211_local *local,
 {
 	int tail_need = 0;
 
-	if (may_encrypt && local->crypto_tx_tailroom_needed_cnt) {
+	/*
+	 * This could be optimised, devices that do full hardware
+	 * crypto (including TKIP MMIC) need no tailroom... But we
+	 * have no drivers for such devices currently.
+	 */
+	if (may_encrypt) {
 		tail_need = IEEE80211_ENCRYPT_TAILROOM;
 		tail_need -= skb_tailroom(skb);
 		tail_need = max_t(int, tail_need, 0);