mac80211: add NAPI support back

NAPI was originally added to mac80211 a long time ago (by John in
commit 4e6cbfd09c66 in July 2010), but then removed years later
(by Stanislaw in commit 30c97120c6c7 in February 2013). No driver
ever used it, so that was fine.

Now I'm adding support for NAPI to our driver, so add some code
to mac80211 again  to support NAPI. John was originally wrapping
some (but not nearly all NAPI-related functions), but that doesn't
scale very well with the number of functions that are there, some
of which are even only inlines. Thus, instead of doing that, let
the drivers manage the NAPI struct, except for napi_add() which is
needed so mac80211 knows how to call napi_gro_receive().

Also remove some no longer needed definitions that were left when
NAPI support was removed.

Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Reviewed-by: Eyal Shapira <eyal@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -1642,10 +1642,6 @@ enum ieee80211_hw_flags {
  *	the hw can report back.
  * @max_rate_tries: maximum number of tries for each stage
  *
- * @napi_weight: weight used for NAPI polling.  You must specify an
- *	appropriate value here if a napi_poll operation is provided
- *	by your driver.
- *
  * @max_rx_aggregation_subframes: maximum buffer size (number of
  *	sub-frames) to be used for A-MPDU block ack receiver
  *	aggregation.
@@ -1699,7 +1695,6 @@ struct ieee80211_hw {
 	int vif_data_size;
 	int sta_data_size;
 	int chanctx_data_size;
-	int napi_weight;
 	u16 queues;
 	u16 max_listen_interval;
 	s8 max_signal;
@@ -2622,8 +2617,6 @@ enum ieee80211_roc_type {
  *	callback. They must then call ieee80211_chswitch_done() to indicate
  *	completion of the channel switch.
  *
- * @napi_poll: Poll Rx queue for incoming data frames.
- *
  * @set_antenna: Set antenna configuration (tx_ant, rx_ant) on the device.
  *	Parameters are bitmaps of allowed antennas to use for TX/RX. Drivers may
  *	reject TX/RX mask combinations they cannot support by returning -EINVAL
@@ -2882,7 +2875,6 @@ struct ieee80211_ops {
 	void (*flush)(struct ieee80211_hw *hw, u32 queues, bool drop);
 	void (*channel_switch)(struct ieee80211_hw *hw,
 			       struct ieee80211_channel_switch *ch_switch);
-	int (*napi_poll)(struct ieee80211_hw *hw, int budget);
 	int (*set_antenna)(struct ieee80211_hw *hw, u32 tx_ant, u32 rx_ant);
 	int (*get_antenna)(struct ieee80211_hw *hw, u32 *tx_ant, u32 *rx_ant);
 
@@ -3164,21 +3156,21 @@ void ieee80211_free_hw(struct ieee80211_hw *hw);
  */
 void ieee80211_restart_hw(struct ieee80211_hw *hw);
 
-/** ieee80211_napi_schedule - schedule NAPI poll
- *
- * Use this function to schedule NAPI polling on a device.
- *
- * @hw: the hardware to start polling
- */
-void ieee80211_napi_schedule(struct ieee80211_hw *hw);
-
-/** ieee80211_napi_complete - complete NAPI polling
- *
- * Use this function to finish NAPI polling on a device.
+/**
+ * ieee80211_napi_add - initialize mac80211 NAPI context
+ * @hw: the hardware to initialize the NAPI context on
+ * @napi: the NAPI context to initialize
+ * @napi_dev: dummy NAPI netdevice, here to not waste the space if the
+ *	driver doesn't use NAPI
+ * @poll: poll function
+ * @weight: default weight
  *
- * @hw: the hardware to stop polling
+ * See also netif_napi_add().
  */
-void ieee80211_napi_complete(struct ieee80211_hw *hw);
+void ieee80211_napi_add(struct ieee80211_hw *hw, struct napi_struct *napi,
+			struct net_device *napi_dev,
+			int (*poll)(struct napi_struct *, int),
+			int weight);
 
 /**
  * ieee80211_rx - receive frame

net/mac80211/ieee80211_i.h

@@ -1242,6 +1242,8 @@ struct ieee80211_local {
 
 	struct ieee80211_sub_if_data __rcu *p2p_sdata;
 
+	struct napi_struct *napi;
+
 	/* virtual monitor interface */
 	struct ieee80211_sub_if_data __rcu *monitor_sdata;
 	struct cfg80211_chan_def monitor_chandef;

net/mac80211/main.c

@@ -1076,6 +1076,18 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 }
 EXPORT_SYMBOL(ieee80211_register_hw);
 
+void ieee80211_napi_add(struct ieee80211_hw *hw, struct napi_struct *napi,
+			struct net_device *napi_dev,
+			int (*poll)(struct napi_struct *, int),
+			int weight)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+
+	netif_napi_add(napi_dev, napi, poll, weight);
+	local->napi = napi;
+}
+EXPORT_SYMBOL_GPL(ieee80211_napi_add);
+
 void ieee80211_unregister_hw(struct ieee80211_hw *hw)
 {
 	struct ieee80211_local *local = hw_to_local(hw);

net/mac80211/rx.c

@@ -1954,7 +1954,10 @@ ieee80211_deliver_skb(struct ieee80211_rx_data *rx)
 		/* deliver to local stack */
 		skb->protocol = eth_type_trans(skb, dev);
 		memset(skb->cb, 0, sizeof(skb->cb));
-		netif_receive_skb(skb);
+		if (rx->local->napi)
+			napi_gro_receive(rx->local->napi, skb);
+		else
+			netif_receive_skb(skb);
 	}
 
 	if (xmit_skb) {