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>
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index c642538..ce566f3 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -600,8 +600,7 @@
 	/*
 	 * 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 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;