mac80211: restructure __ieee80211_rx

This patch makes a separation between Rx frame pre-handling which stays in
__ieee80211_rx and Rx frame handlers, moving to __ieee80211_rx_handle_packet.
Although this separation has no affect in regular mode of operation, this kind
of mechanism will be used in A-MPDU frames reordering as it allows accumulation
of frames during pre-handling, dispatching them to later handling when necessary.

Signed-off-by: Ron Rindjunsky <ron.rindjunsky@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mac80211/rx.c

@@ -288,11 +288,11 @@ ieee80211_rx_h_parse_qos(struct ieee80211_txrx_data *rx)
 	return TXRX_CONTINUE;
 }
 
-static ieee80211_txrx_result
-ieee80211_rx_h_load_stats(struct ieee80211_txrx_data *rx)
+
+u32 ieee80211_rx_load_stats(struct ieee80211_local *local,
+			      struct sk_buff *skb,
+			      struct ieee80211_rx_status *status)
 {
-	struct ieee80211_local *local = rx->local;
-	struct sk_buff *skb = rx->skb;
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 	u32 load = 0, hdrtime;
 	struct ieee80211_rate *rate;
@@ -306,7 +306,7 @@ ieee80211_rx_h_load_stats(struct ieee80211_txrx_data *rx)
 
 	rate = &mode->rates[0];
 	for (i = 0; i < mode->num_rates; i++) {
-		if (mode->rates[i].val == rx->u.rx.status->rate) {
+		if (mode->rates[i].val == status->rate) {
 			rate = &mode->rates[i];
 			break;
 		}
@@ -331,15 +331,13 @@ ieee80211_rx_h_load_stats(struct ieee80211_txrx_data *rx)
 	/* Divide channel_use by 8 to avoid wrapping around the counter */
 	load >>= CHAN_UTIL_SHIFT;
 	local->channel_use_raw += load;
-	rx->u.rx.load = load;
 
-	return TXRX_CONTINUE;
+	return load;
 }
 
 ieee80211_rx_handler ieee80211_rx_pre_handlers[] =
 {
 	ieee80211_rx_h_parse_qos,
-	ieee80211_rx_h_load_stats,
 	NULL
 };
 
@@ -1613,11 +1611,11 @@ static int prepare_for_handlers(struct ieee80211_sub_if_data *sdata,
 }
 
 /*
- * This is the receive path handler. It is called by a low level driver when an
- * 802.11 MPDU is received from the hardware.
+ * This is the actual Rx frames handler. as it blongs to Rx path it must
+ * be called with rcu_read_lock protection.
  */
-void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
-		    struct ieee80211_rx_status *status)
+void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw, struct sk_buff *skb,
+			    struct ieee80211_rx_status *status, u32 load)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
 	struct ieee80211_sub_if_data *sdata;
@@ -1625,37 +1623,19 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
 	struct ieee80211_hdr *hdr;
 	struct ieee80211_txrx_data rx;
 	u16 type;
-	int prepres;
+	int prepares;
 	struct ieee80211_sub_if_data *prev = NULL;
 	struct sk_buff *skb_new;
 	u8 *bssid;
 	int hdrlen;
 
-	/*
-	 * key references and virtual interfaces are protected using RCU
-	 * and this requires that we are in a read-side RCU section during
-	 * receive processing
-	 */
-	rcu_read_lock();
-
-	/*
-	 * Frames with failed FCS/PLCP checksum are not returned,
-	 * all other frames are returned without radiotap header
-	 * if it was previously present.
-	 * Also, frames with less than 16 bytes are dropped.
-	 */
-	skb = ieee80211_rx_monitor(local, skb, status);
-	if (!skb) {
-		rcu_read_unlock();
-		return;
-	}
-
 	hdr = (struct ieee80211_hdr *) skb->data;
 	memset(&rx, 0, sizeof(rx));
 	rx.skb = skb;
 	rx.local = local;
 
 	rx.u.rx.status = status;
+	rx.u.rx.load = load;
 	rx.fc = le16_to_cpu(hdr->frame_control);
 	type = rx.fc & IEEE80211_FCTL_FTYPE;
 
@@ -1714,11 +1694,11 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
 			continue;
 
 		rx.flags |= IEEE80211_TXRXD_RXRA_MATCH;
-		prepres = prepare_for_handlers(sdata, bssid, &rx, hdr);
+		prepares = prepare_for_handlers(sdata, bssid, &rx, hdr);
 		/* prepare_for_handlers can change sta */
 		sta = rx.sta;
 
-		if (!prepres)
+		if (!prepares)
 			continue;
 
 		/*
@@ -1765,11 +1745,45 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
 		dev_kfree_skb(skb);
 
  end:
-	rcu_read_unlock();
-
 	if (sta)
 		sta_info_put(sta);
 }
+
+/*
+ * This is the receive path handler. It is called by a low level driver when an
+ * 802.11 MPDU is received from the hardware.
+ */
+void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
+		    struct ieee80211_rx_status *status)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	u32 pkt_load;
+
+	/*
+	 * key references and virtual interfaces are protected using RCU
+	 * and this requires that we are in a read-side RCU section during
+	 * receive processing
+	 */
+	rcu_read_lock();
+
+	/*
+	 * Frames with failed FCS/PLCP checksum are not returned,
+	 * all other frames are returned without radiotap header
+	 * if it was previously present.
+	 * Also, frames with less than 16 bytes are dropped.
+	 */
+	skb = ieee80211_rx_monitor(local, skb, status);
+	if (!skb) {
+		rcu_read_unlock();
+		return;
+	}
+
+	pkt_load = ieee80211_rx_load_stats(local, skb, status);
+
+	__ieee80211_rx_handle_packet(hw, skb, status, pkt_load);
+
+	rcu_read_unlock();
+}
 EXPORT_SYMBOL(__ieee80211_rx);
 
 /* This is a version of the rx handler that can be called from hard irq