---

yaml
---
r: 368423
b: refs/heads/master
c: 8d1f7ec
h: refs/heads/master
i:
  368421: 7ae0fb5
  368419: 104f654
  368415: 42485b0
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a87121051ce80831a302c67286119013104f7a5a
+refs/heads/master: 8d1f7ecd2af55c0c82ffd2bff0ef0b26f16ea69f

trunk/net/mac80211/cfg.c

@@ -254,7 +254,7 @@ static int ieee80211_del_key(struct wiphy *wiphy, struct net_device *dev,
 		goto out_unlock;
 	}
 
-	__ieee80211_key_free(key);
+	__ieee80211_key_free(key, true);
 
 	ret = 0;
  out_unlock:

trunk/net/mac80211/ieee80211_i.h

@@ -680,6 +680,8 @@ struct ieee80211_sub_if_data {
 
 	/* count for keys needing tailroom space allocation */
 	int crypto_tx_tailroom_needed_cnt;
+	int crypto_tx_tailroom_pending_dec;
+	struct delayed_work dec_tailroom_needed_wk;
 
 	struct net_device *dev;
 	struct ieee80211_local *local;

trunk/net/mac80211/iface.c

@@ -1543,6 +1543,8 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
 	INIT_WORK(&sdata->cleanup_stations_wk, ieee80211_cleanup_sdata_stas_wk);
 	INIT_DELAYED_WORK(&sdata->dfs_cac_timer_work,
 			  ieee80211_dfs_cac_timer_work);
+	INIT_DELAYED_WORK(&sdata->dec_tailroom_needed_wk,
+			  ieee80211_delayed_tailroom_dec);
 
 	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
 		struct ieee80211_supported_band *sband;

trunk/net/mac80211/key.c

@@ -397,7 +397,8 @@ struct ieee80211_key *ieee80211_key_alloc(u32 cipher, int idx, size_t key_len,
 	return key;
 }
 
-static void __ieee80211_key_destroy(struct ieee80211_key *key)
+static void __ieee80211_key_destroy(struct ieee80211_key *key,
+				    bool delay_tailroom)
 {
 	if (!key)
 		return;
@@ -416,8 +417,18 @@ static void __ieee80211_key_destroy(struct ieee80211_key *key)
 	if (key->conf.cipher == WLAN_CIPHER_SUITE_AES_CMAC)
 		ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
 	if (key->local) {
+		struct ieee80211_sub_if_data *sdata = key->sdata;
+
 		ieee80211_debugfs_key_remove(key);
-		key->sdata->crypto_tx_tailroom_needed_cnt--;
+
+		if (delay_tailroom) {
+			/* see ieee80211_delayed_tailroom_dec */
+			sdata->crypto_tx_tailroom_pending_dec++;
+			schedule_delayed_work(&sdata->dec_tailroom_needed_wk,
+					      HZ/2);
+		} else {
+			sdata->crypto_tx_tailroom_needed_cnt--;
+		}
 	}
 
 	kfree(key);
@@ -452,7 +463,7 @@ int ieee80211_key_link(struct ieee80211_key *key,
 	increment_tailroom_need_count(sdata);
 
 	__ieee80211_key_replace(sdata, sta, pairwise, old_key, key);
-	__ieee80211_key_destroy(old_key);
+	__ieee80211_key_destroy(old_key, true);
 
 	ieee80211_debugfs_key_add(key);
 
@@ -463,7 +474,7 @@ int ieee80211_key_link(struct ieee80211_key *key,
 	return ret;
 }
 
-void __ieee80211_key_free(struct ieee80211_key *key)
+void __ieee80211_key_free(struct ieee80211_key *key, bool delay_tailroom)
 {
 	if (!key)
 		return;
@@ -475,14 +486,14 @@ void __ieee80211_key_free(struct ieee80211_key *key)
 		__ieee80211_key_replace(key->sdata, key->sta,
 				key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE,
 				key, NULL);
-	__ieee80211_key_destroy(key);
+	__ieee80211_key_destroy(key, delay_tailroom);
 }
 
 void ieee80211_key_free(struct ieee80211_local *local,
 			struct ieee80211_key *key)
 {
 	mutex_lock(&local->key_mtx);
-	__ieee80211_key_free(key);
+	__ieee80211_key_free(key, true);
 	mutex_unlock(&local->key_mtx);
 }
 
@@ -544,18 +555,56 @@ void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 {
 	struct ieee80211_key *key, *tmp;
 
+	cancel_delayed_work_sync(&sdata->dec_tailroom_needed_wk);
+
 	mutex_lock(&sdata->local->key_mtx);
 
+	sdata->crypto_tx_tailroom_needed_cnt -=
+		sdata->crypto_tx_tailroom_pending_dec;
+	sdata->crypto_tx_tailroom_pending_dec = 0;
+
 	ieee80211_debugfs_key_remove_mgmt_default(sdata);
 
 	list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
-		__ieee80211_key_free(key);
+		__ieee80211_key_free(key, false);
 
 	ieee80211_debugfs_key_update_default(sdata);
 
+	WARN_ON_ONCE(sdata->crypto_tx_tailroom_needed_cnt ||
+		     sdata->crypto_tx_tailroom_pending_dec);
+
 	mutex_unlock(&sdata->local->key_mtx);
 }
 
+void ieee80211_delayed_tailroom_dec(struct work_struct *wk)
+{
+	struct ieee80211_sub_if_data *sdata;
+
+	sdata = container_of(wk, struct ieee80211_sub_if_data,
+			     dec_tailroom_needed_wk.work);
+
+	/*
+	 * The reason for the delayed tailroom needed decrementing is to
+	 * make roaming faster: during roaming, all keys are first deleted
+	 * and then new keys are installed. The first new key causes the
+	 * crypto_tx_tailroom_needed_cnt to go from 0 to 1, which invokes
+	 * the cost of synchronize_net() (which can be slow). Avoid this
+	 * by deferring the crypto_tx_tailroom_needed_cnt decrementing on
+	 * key removal for a while, so if we roam the value is larger than
+	 * zero and no 0->1 transition happens.
+	 *
+	 * The cost is that if the AP switching was from an AP with keys
+	 * to one without, we still allocate tailroom while it would no
+	 * longer be needed. However, in the typical (fast) roaming case
+	 * within an ESS this usually won't happen.
+	 */
+
+	mutex_lock(&sdata->local->key_mtx);
+	sdata->crypto_tx_tailroom_needed_cnt -=
+		sdata->crypto_tx_tailroom_pending_dec;
+	sdata->crypto_tx_tailroom_pending_dec = 0;
+	mutex_unlock(&sdata->local->key_mtx);
+}
 
 void ieee80211_gtk_rekey_notify(struct ieee80211_vif *vif, const u8 *bssid,
 				const u8 *replay_ctr, gfp_t gfp)

trunk/net/mac80211/key.h

@@ -134,7 +134,7 @@ struct ieee80211_key *ieee80211_key_alloc(u32 cipher, int idx, size_t key_len,
 int __must_check ieee80211_key_link(struct ieee80211_key *key,
 				    struct ieee80211_sub_if_data *sdata,
 				    struct sta_info *sta);
-void __ieee80211_key_free(struct ieee80211_key *key);
+void __ieee80211_key_free(struct ieee80211_key *key, bool delay_tailroom);
 void ieee80211_key_free(struct ieee80211_local *local,
 			struct ieee80211_key *key);
 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx,
@@ -147,4 +147,6 @@ void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata);
 #define key_mtx_dereference(local, ref) \
 	rcu_dereference_protected(ref, lockdep_is_held(&((local)->key_mtx)))
 
+void ieee80211_delayed_tailroom_dec(struct work_struct *wk);
+
 #endif /* IEEE80211_KEY_H */

trunk/net/mac80211/sta_info.c

@@ -794,9 +794,11 @@ int __must_check __sta_info_destroy(struct sta_info *sta)
 
 	mutex_lock(&local->key_mtx);
 	for (i = 0; i < NUM_DEFAULT_KEYS; i++)
-		__ieee80211_key_free(key_mtx_dereference(local, sta->gtk[i]));
+		__ieee80211_key_free(key_mtx_dereference(local, sta->gtk[i]),
+				     true);
 	if (sta->ptk)
-		__ieee80211_key_free(key_mtx_dereference(local, sta->ptk));
+		__ieee80211_key_free(key_mtx_dereference(local, sta->ptk),
+				     true);
 	mutex_unlock(&local->key_mtx);
 
 	sta->dead = true;