iwlwifi: introduce statistics lock

The statistics are currently only half-heartedly
locked against concurrent reading & modification
so introduce a lock to really protect them.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-dev.h b/drivers/net/wireless/iwlwifi/iwl-dev.h
index dc57522..daf2330 100644
--- a/drivers/net/wireless/iwlwifi/iwl-dev.h
+++ b/drivers/net/wireless/iwlwifi/iwl-dev.h
@@ -851,6 +851,7 @@
 		struct statistics_bt_activity bt_activity;
 		__le32 num_bt_kills, accum_num_bt_kills;
 #endif
+		spinlock_t lock;
 	} statistics;
 #ifdef CONFIG_IWLWIFI_DEBUGFS
 	struct {