mac80211: batch key free synchronize_net()

Instead of calling synchronize_net() for every key
on an interface or when a station is removed, do it
only once for all keys in both of these cases.

As a side-effect, removing station keys now always
calls synchronize_net() even if there are no keys,
which fixes an issue with station removal happening
in the driver while the station could still be used
for TX.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 73 insertions, 22 deletions

diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 953887bdc638..67059b88fea5 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -406,18 +406,9 @@ static void ieee80211_key_free_common(struct ieee80211_key *key)
         kfree(key);
 }
 
-static void ieee80211_key_destroy(struct ieee80211_key *key,
-                                  bool delay_tailroom)
+static void __ieee80211_key_destroy(struct ieee80211_key *key,
+                                    bool delay_tailroom)
 {
-        if (!key)
-                return;
-
-        /*
-         * Synchronize so the TX path can no longer be using
-         * this key before we free/remove it.
-         */
-        synchronize_net();
-
         if (key->local)
                 ieee80211_key_disable_hw_accel(key);
 
@@ -439,6 +430,21 @@ static void ieee80211_key_destroy(struct ieee80211_key *key,
         ieee80211_key_free_common(key);
 }
 
+static void ieee80211_key_destroy(struct ieee80211_key *key,
+                                  bool delay_tailroom)
+{
+        if (!key)
+                return;
+
+        /*
+         * Synchronize so the TX path can no longer be using
+         * this key before we free/remove it.
+         */
+        synchronize_net();
+
+        __ieee80211_key_destroy(key, delay_tailroom);
+}
+
 void ieee80211_key_free_unused(struct ieee80211_key *key)
 {
         WARN_ON(key->sdata || key->local);
@@ -560,6 +566,7 @@ EXPORT_SYMBOL(ieee80211_iter_keys);
 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 {
         struct ieee80211_key *key, *tmp;
+        LIST_HEAD(keys);
 
         cancel_delayed_work_sync(&sdata->dec_tailroom_needed_wk);
 
@@ -571,17 +578,65 @@ void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 
         ieee80211_debugfs_key_remove_mgmt_default(sdata);
 
-        list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
-                ieee80211_key_free(key, false);
+        list_for_each_entry_safe(key, tmp, &sdata->key_list, list) {
+                ieee80211_key_replace(key->sdata, key->sta,
+                                key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE,
+                                key, NULL);
+                list_add_tail(&key->list, &keys);
+        }
 
         ieee80211_debugfs_key_update_default(sdata);
 
+        if (!list_empty(&keys)) {
+                synchronize_net();
+                list_for_each_entry_safe(key, tmp, &keys, list)
+                        __ieee80211_key_destroy(key, false);
+        }
+
         WARN_ON_ONCE(sdata->crypto_tx_tailroom_needed_cnt ||
                      sdata->crypto_tx_tailroom_pending_dec);
 
         mutex_unlock(&sdata->local->key_mtx);
 }
 
+void ieee80211_free_sta_keys(struct ieee80211_local *local,
+                             struct sta_info *sta)
+{
+        struct ieee80211_key *key, *tmp;
+        LIST_HEAD(keys);
+        int i;
+
+        mutex_lock(&local->key_mtx);
+        for (i = 0; i < NUM_DEFAULT_KEYS; i++) {
+                key = key_mtx_dereference(local, sta->gtk[i]);
+                if (!key)
+                        continue;
+                ieee80211_key_replace(key->sdata, key->sta,
+                                key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE,
+                                key, NULL);
+                list_add(&key->list, &keys);
+        }
+
+        key = key_mtx_dereference(local, sta->ptk);
+        if (key) {
+                ieee80211_key_replace(key->sdata, key->sta,
+                                key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE,
+                                key, NULL);
+                list_add(&key->list, &keys);
+        }
+
+        /*
+         * NB: the station code relies on this being
+         * done even if there aren't any keys
+         */
+        synchronize_net();
+
+        list_for_each_entry_safe(key, tmp, &keys, list)
+                __ieee80211_key_destroy(key, true);
+
+        mutex_unlock(&local->key_mtx);
+}
+
 void ieee80211_delayed_tailroom_dec(struct work_struct *wk)
 {
         struct ieee80211_sub_if_data *sdata;
diff --git a/net/mac80211/key.h b/net/mac80211/key.h
index a353ddd63b5b..e8de3e6d7804 100644
--- a/net/mac80211/key.h
+++ b/net/mac80211/key.h
@@ -141,6 +141,8 @@ void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx,
 void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
                                     int idx);
 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata);
+void ieee80211_free_sta_keys(struct ieee80211_local *local,
+                             struct sta_info *sta);
 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata);
 
 #define key_mtx_dereference(local, ref) \
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 2961f3d6b209..11216bc13b27 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -783,7 +783,7 @@ int __must_check __sta_info_destroy(struct sta_info *sta)
 {
         struct ieee80211_local *local;
         struct ieee80211_sub_if_data *sdata;
-        int ret, i;
+        int ret;
 
         might_sleep();
 
@@ -810,14 +810,8 @@ int __must_check __sta_info_destroy(struct sta_info *sta)
 
         list_del_rcu(&sta->list);
 
-        mutex_lock(&local->key_mtx);
-        for (i = 0; i < NUM_DEFAULT_KEYS; i++)
-                ieee80211_key_free(key_mtx_dereference(local, sta->gtk[i]),
-                                   true);
-        if (sta->ptk)
-                ieee80211_key_free(key_mtx_dereference(local, sta->ptk),
-                                   true);
-        mutex_unlock(&local->key_mtx);
+        /* this always calls synchronize_net() */
+        ieee80211_free_sta_keys(local, sta);
 
         sta->dead = true;