mac80211: fix spinlock recursion

When STAs are expired, we need to hold the sta_lock. Using
the same lock for keys too would then mean we'd need another
key free function, and that'll just lead to confusion, so just
use a new spinlock for all key lists.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/ieee80211_i.h

@@ -600,8 +600,7 @@ struct ieee80211_local {
 	/*
 	 * The lock only protects the list, hash, timer and counter
 	 * against manipulation, reads are done in RCU. Additionally,
-	 * the lock protects each BSS's TIM bitmap, a few items in
-	 * STA info structures and various key pointers.
+	 * the lock protects each BSS's TIM bitmap.
 	 */
 	spinlock_t sta_lock;
 	unsigned long num_sta;
@@ -635,6 +634,13 @@ struct ieee80211_local {
 
 	struct list_head interfaces;
 
+	/*
+	 * Key lock, protects sdata's key_list and sta_info's
+	 * key pointers (write access, they're RCU.)
+	 */
+	spinlock_t key_lock;
+
+
 	bool sta_sw_scanning;
 	bool sta_hw_scanning;
 	int scan_channel_idx;

net/mac80211/key.c

@@ -210,9 +210,9 @@ void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&sdata->local->sta_lock, flags);
+	spin_lock_irqsave(&sdata->local->key_lock, flags);
 	__ieee80211_set_default_key(sdata, idx);
-	spin_unlock_irqrestore(&sdata->local->sta_lock, flags);
+	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 }
 
 
@@ -339,7 +339,7 @@ void ieee80211_key_link(struct ieee80211_key *key,
 		}
 	}
 
-	spin_lock_irqsave(&sdata->local->sta_lock, flags);
+	spin_lock_irqsave(&sdata->local->key_lock, flags);
 
 	if (sta)
 		old_key = sta->key;
@@ -348,7 +348,7 @@ void ieee80211_key_link(struct ieee80211_key *key,
 
 	__ieee80211_key_replace(sdata, sta, old_key, key);
 
-	spin_unlock_irqrestore(&sdata->local->sta_lock, flags);
+	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 
 	/* free old key later */
 	add_todo(old_key, KEY_FLAG_TODO_DELETE);
@@ -377,9 +377,9 @@ void ieee80211_key_free(struct ieee80211_key *key)
 	if (!key)
 		return;
 
-	spin_lock_irqsave(&key->sdata->local->sta_lock, flags);
+	spin_lock_irqsave(&key->sdata->local->key_lock, flags);
 	__ieee80211_key_free(key);
-	spin_unlock_irqrestore(&key->sdata->local->sta_lock, flags);
+	spin_unlock_irqrestore(&key->sdata->local->key_lock, flags);
 }
 
 /*
@@ -397,10 +397,10 @@ static void ieee80211_todo_for_each_key(struct ieee80211_sub_if_data *sdata,
 
 	might_sleep();
 
-	spin_lock_irqsave(&sdata->local->sta_lock, flags);
+	spin_lock_irqsave(&sdata->local->key_lock, flags);
 	list_for_each_entry(key, &sdata->key_list, list)
 		add_todo(key, todo_flags);
-	spin_unlock_irqrestore(&sdata->local->sta_lock, flags);
+	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 
 	ieee80211_key_todo();
 }
@@ -506,10 +506,10 @@ void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 
 	ieee80211_debugfs_key_remove_default(sdata);
 
-	spin_lock_irqsave(&sdata->local->sta_lock, flags);
+	spin_lock_irqsave(&sdata->local->key_lock, flags);
 	list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
 		__ieee80211_key_free(key);
-	spin_unlock_irqrestore(&sdata->local->sta_lock, flags);
+	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
 
 	__ieee80211_key_todo();
 

net/mac80211/main.c

@@ -1587,6 +1587,8 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
 
 	INIT_LIST_HEAD(&local->interfaces);
 
+	spin_lock_init(&local->key_lock);
+
 	INIT_DELAYED_WORK(&local->scan_work, ieee80211_sta_scan_work);
 
 	sta_info_init(local);