mac80211: get rid of function pointers in TX path

This changes the TX path to no longer use function pointers for
TX handlers but rather invoke them directly. If debugging is
enabled, mark the TX handlers noinline because otherwise they
all get inlined into invoke_tx_handlers() which makes it harder
to see where a bug is.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/ieee80211_i.h

@@ -954,4 +954,10 @@ int ieee80211_frame_duration(struct ieee80211_local *local, size_t len,
 void mac80211_ev_michael_mic_failure(struct net_device *dev, int keyidx,
 				     struct ieee80211_hdr *hdr);
 
+#ifdef CONFIG_MAC80211_DEBUG
+#define debug_noinline noinline
+#else
+#define debug_noinline
+#endif
+
 #endif /* IEEE80211_I_H */

net/mac80211/tx.c

@@ -220,7 +220,7 @@ static int inline is_ieee80211_device(struct net_device *dev,
 
 /* tx handlers */
 
-static ieee80211_tx_result
+static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_check_assoc(struct ieee80211_tx_data *tx)
 {
 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
@@ -274,7 +274,7 @@ ieee80211_tx_h_check_assoc(struct ieee80211_tx_data *tx)
 	return TX_CONTINUE;
 }
 
-static ieee80211_tx_result
+static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_sequence(struct ieee80211_tx_data *tx)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
@@ -432,7 +432,7 @@ ieee80211_tx_h_unicast_ps_buf(struct ieee80211_tx_data *tx)
 	return TX_CONTINUE;
 }
 
-static ieee80211_tx_result
+static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_ps_buf(struct ieee80211_tx_data *tx)
 {
 	if (unlikely(tx->flags & IEEE80211_TX_PS_BUFFERED))
@@ -444,7 +444,7 @@ ieee80211_tx_h_ps_buf(struct ieee80211_tx_data *tx)
 		return ieee80211_tx_h_multicast_ps_buf(tx);
 }
 
-static ieee80211_tx_result
+static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
 {
 	struct ieee80211_key *key;
@@ -493,7 +493,7 @@ ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
 	return TX_CONTINUE;
 }
 
-static ieee80211_tx_result
+static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
 {
 	struct rate_selection rsel;
@@ -537,7 +537,7 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
 	return TX_CONTINUE;
 }
 
-static ieee80211_tx_result
+static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_misc(struct ieee80211_tx_data *tx)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
@@ -632,7 +632,7 @@ ieee80211_tx_h_misc(struct ieee80211_tx_data *tx)
 	return TX_CONTINUE;
 }
 
-static ieee80211_tx_result
+static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_fragment(struct ieee80211_tx_data *tx)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
@@ -724,7 +724,7 @@ ieee80211_tx_h_fragment(struct ieee80211_tx_data *tx)
 	return TX_DROP;
 }
 
-static ieee80211_tx_result
+static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_encrypt(struct ieee80211_tx_data *tx)
 {
 	if (!tx->key)
@@ -744,7 +744,7 @@ ieee80211_tx_h_encrypt(struct ieee80211_tx_data *tx)
 	return TX_DROP;
 }
 
-static ieee80211_tx_result
+static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_calculate_duration(struct ieee80211_tx_data *tx)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
@@ -774,7 +774,7 @@ ieee80211_tx_h_calculate_duration(struct ieee80211_tx_data *tx)
 	return TX_CONTINUE;
 }
 
-static ieee80211_tx_result
+static ieee80211_tx_result debug_noinline
 ieee80211_tx_h_stats(struct ieee80211_tx_data *tx)
 {
 	int i;
@@ -795,24 +795,6 @@ ieee80211_tx_h_stats(struct ieee80211_tx_data *tx)
 }
 
 
-typedef ieee80211_tx_result (*ieee80211_tx_handler)(struct ieee80211_tx_data *);
-static ieee80211_tx_handler ieee80211_tx_handlers[] =
-{
-	ieee80211_tx_h_check_assoc,
-	ieee80211_tx_h_sequence,
-	ieee80211_tx_h_ps_buf,
-	ieee80211_tx_h_select_key,
-	ieee80211_tx_h_michael_mic_add,
-	ieee80211_tx_h_rate_ctrl,
-	ieee80211_tx_h_misc,
-	ieee80211_tx_h_fragment,
-	/* handlers after fragment must be aware of tx info fragmentation! */
-	ieee80211_tx_h_encrypt,
-	ieee80211_tx_h_calculate_duration,
-	ieee80211_tx_h_stats,
-	NULL
-};
-
 /* actual transmit path */
 
 /*
@@ -1111,16 +1093,29 @@ static int __ieee80211_tx(struct ieee80211_local *local, struct sk_buff *skb,
 static int invoke_tx_handlers(struct ieee80211_tx_data *tx)
 {
 	struct sk_buff *skb = tx->skb;
-	ieee80211_tx_handler *handler;
 	ieee80211_tx_result res = TX_DROP;
 	int i;
 
-	for (handler = ieee80211_tx_handlers; *handler != NULL; handler++) {
-		res = (*handler)(tx);
-		if (res != TX_CONTINUE)
-			break;
-	}
+#define CALL_TXH(txh)		\
+	res = txh(tx);		\
+	if (res != TX_CONTINUE)	\
+		goto txh_done;
+
+	CALL_TXH(ieee80211_tx_h_check_assoc)
+	CALL_TXH(ieee80211_tx_h_sequence)
+	CALL_TXH(ieee80211_tx_h_ps_buf)
+	CALL_TXH(ieee80211_tx_h_select_key)
+	CALL_TXH(ieee80211_tx_h_michael_mic_add)
+	CALL_TXH(ieee80211_tx_h_rate_ctrl)
+	CALL_TXH(ieee80211_tx_h_misc)
+	CALL_TXH(ieee80211_tx_h_fragment)
+	/* handlers after fragment must be aware of tx info fragmentation! */
+	CALL_TXH(ieee80211_tx_h_encrypt)
+	CALL_TXH(ieee80211_tx_h_calculate_duration)
+	CALL_TXH(ieee80211_tx_h_stats)
+#undef CALL_TXH
 
+ txh_done:
 	if (unlikely(res == TX_DROP)) {
 		I802_DEBUG_INC(tx->local->tx_handlers_drop);
 		dev_kfree_skb(skb);