mac80211: remove short frame test and counter

Short frames less than 16 octets are already blocked in the monitor
code by the should_drop_frame() function, and cannot get into the
regular RX path. Therefore, this check can never trigger and the
counter invariably stays zero. Remove the useless code.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/debugfs.c

@@ -277,7 +277,6 @@ void debugfs_hw_add(struct ieee80211_local *local)
 	DEBUGFS_STATS_ADD(rx_handlers_queued);
 	DEBUGFS_STATS_ADD(rx_handlers_drop_nullfunc);
 	DEBUGFS_STATS_ADD(rx_handlers_drop_defrag);
-	DEBUGFS_STATS_ADD(rx_handlers_drop_short);
 	DEBUGFS_STATS_ADD(tx_expand_skb_head);
 	DEBUGFS_STATS_ADD(tx_expand_skb_head_cloned);
 	DEBUGFS_STATS_ADD(rx_expand_skb_head_defrag);

net/mac80211/ieee80211_i.h

@@ -1286,7 +1286,6 @@ struct ieee80211_local {
 	unsigned int rx_handlers_queued;
 	unsigned int rx_handlers_drop_nullfunc;
 	unsigned int rx_handlers_drop_defrag;
-	unsigned int rx_handlers_drop_short;
 	unsigned int tx_expand_skb_head;
 	unsigned int tx_expand_skb_head_cloned;
 	unsigned int rx_expand_skb_head_defrag;

net/mac80211/rx.c

@@ -1093,11 +1093,6 @@ ieee80211_rx_h_check(struct ieee80211_rx_data *rx)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
 
-	if (unlikely(rx->skb->len < 16)) {
-		I802_DEBUG_INC(rx->local->rx_handlers_drop_short);
-		return RX_DROP_MONITOR;
-	}
-
 	/* Drop disallowed frame classes based on STA auth/assoc state;
 	 * IEEE 802.11, Chap 5.5.
 	 *