mac80211: fix skb buffering issue

Since I removed the master netdev, we've been
keeping internal queues only, and even before
that we never told the networking stack above
the virtual interfaces about congestion. This
means that packets are queued in mac80211 and
the upper layers never know, possibly leading
to memory exhaustion and other problems.

This patch makes all interfaces multiqueue and
uses ndo_select_queue to put the packets into
queues per AC. Additionally, when the driver
stops a queue, we now stop all corresponding
queues for the virtual interfaces as well.

The injection case will use VO by default for
non-data frames, and BE for data frames, but
downgrade any data frames according to ACM. It
needs to be fleshed out in the future to allow
chosing the queue/AC in radiotap.
Reported-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: stable@kernel.org [2.6.32]
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/iface.c

@@ -15,12 +15,14 @@
 #include <linux/netdevice.h>
 #include <linux/rtnetlink.h>
 #include <net/mac80211.h>
+#include <net/ieee80211_radiotap.h>
 #include "ieee80211_i.h"
 #include "sta_info.h"
 #include "debugfs_netdev.h"
 #include "mesh.h"
 #include "led.h"
 #include "driver-ops.h"
+#include "wme.h"
 
 /**
  * DOC: Interface list locking
@@ -644,6 +646,12 @@ static void ieee80211_teardown_sdata(struct net_device *dev)
 	WARN_ON(flushed);
 }
 
+static u16 ieee80211_netdev_select_queue(struct net_device *dev,
+					 struct sk_buff *skb)
+{
+	return ieee80211_select_queue(IEEE80211_DEV_TO_SUB_IF(dev), skb);
+}
+
 static const struct net_device_ops ieee80211_dataif_ops = {
 	.ndo_open		= ieee80211_open,
 	.ndo_stop		= ieee80211_stop,
@@ -652,8 +660,34 @@ static const struct net_device_ops ieee80211_dataif_ops = {
 	.ndo_set_multicast_list = ieee80211_set_multicast_list,
 	.ndo_change_mtu 	= ieee80211_change_mtu,
 	.ndo_set_mac_address 	= eth_mac_addr,
+	.ndo_select_queue	= ieee80211_netdev_select_queue,
 };
 
+static u16 ieee80211_monitor_select_queue(struct net_device *dev,
+					  struct sk_buff *skb)
+{
+	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_hdr *hdr;
+	struct ieee80211_radiotap_header *rtap = (void *)skb->data;
+
+	if (local->hw.queues < 4)
+		return 0;
+
+	if (skb->len < 4 ||
+	    skb->len < rtap->it_len + 2 /* frame control */)
+		return 0; /* doesn't matter, frame will be dropped */
+
+	hdr = (void *)((u8 *)skb->data + rtap->it_len);
+
+	if (!ieee80211_is_data(hdr->frame_control)) {
+		skb->priority = 7;
+		return ieee802_1d_to_ac[skb->priority];
+	}
+
+	return ieee80211_downgrade_queue(local, skb);
+}
+
 static const struct net_device_ops ieee80211_monitorif_ops = {
 	.ndo_open		= ieee80211_open,
 	.ndo_stop		= ieee80211_stop,
@@ -662,6 +696,7 @@ static const struct net_device_ops ieee80211_monitorif_ops = {
 	.ndo_set_multicast_list = ieee80211_set_multicast_list,
 	.ndo_change_mtu 	= ieee80211_change_mtu,
 	.ndo_set_mac_address 	= eth_mac_addr,
+	.ndo_select_queue	= ieee80211_monitor_select_queue,
 };
 
 static void ieee80211_if_setup(struct net_device *dev)
@@ -768,8 +803,8 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
 
 	ASSERT_RTNL();
 
-	ndev = alloc_netdev(sizeof(*sdata) + local->hw.vif_data_size,
-			    name, ieee80211_if_setup);
+	ndev = alloc_netdev_mq(sizeof(*sdata) + local->hw.vif_data_size,
+			       name, ieee80211_if_setup, local->hw.queues);
 	if (!ndev)
 		return -ENOMEM;
 	dev_net_set(ndev, wiphy_net(local->hw.wiphy));

net/mac80211/rx.c

@@ -1746,7 +1746,9 @@ ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
 			memset(info, 0, sizeof(*info));
 			info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
 			info->control.vif = &rx->sdata->vif;
-			ieee80211_select_queue(local, fwd_skb);
+			skb_set_queue_mapping(skb,
+				ieee80211_select_queue(rx->sdata, fwd_skb));
+			ieee80211_set_qos_hdr(local, skb);
 			if (is_multicast_ether_addr(fwd_hdr->addr1))
 				IEEE80211_IFSTA_MESH_CTR_INC(&sdata->u.mesh,
 								fwded_mcast);

net/mac80211/tx.c

@@ -1512,7 +1512,7 @@ static void ieee80211_xmit(struct ieee80211_sub_if_data *sdata,
 				return;
 			}
 
-	ieee80211_select_queue(local, skb);
+	ieee80211_set_qos_hdr(local, skb);
 	ieee80211_tx(sdata, skb, false);
 	rcu_read_unlock();
 }
@@ -2291,6 +2291,9 @@ void ieee80211_tx_skb(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 	skb_set_network_header(skb, 0);
 	skb_set_transport_header(skb, 0);
 
+	/* send all internal mgmt frames on VO */
+	skb_set_queue_mapping(skb, 0);
+
 	/*
 	 * The other path calling ieee80211_xmit is from the tasklet,
 	 * and while we can handle concurrent transmissions locking

net/mac80211/util.c

@@ -269,6 +269,7 @@ static void __ieee80211_wake_queue(struct ieee80211_hw *hw, int queue,
 				   enum queue_stop_reason reason)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
+	struct ieee80211_sub_if_data *sdata;
 
 	if (WARN_ON(queue >= hw->queues))
 		return;
@@ -281,6 +282,11 @@ static void __ieee80211_wake_queue(struct ieee80211_hw *hw, int queue,
 
 	if (!skb_queue_empty(&local->pending[queue]))
 		tasklet_schedule(&local->tx_pending_tasklet);
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sdata, &local->interfaces, list)
+		netif_tx_wake_queue(netdev_get_tx_queue(sdata->dev, queue));
+	rcu_read_unlock();
 }
 
 void ieee80211_wake_queue_by_reason(struct ieee80211_hw *hw, int queue,
@@ -305,11 +311,17 @@ static void __ieee80211_stop_queue(struct ieee80211_hw *hw, int queue,
 				   enum queue_stop_reason reason)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
+	struct ieee80211_sub_if_data *sdata;
 
 	if (WARN_ON(queue >= hw->queues))
 		return;
 
 	__set_bit(reason, &local->queue_stop_reasons[queue]);
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sdata, &local->interfaces, list)
+		netif_tx_stop_queue(netdev_get_tx_queue(sdata->dev, queue));
+	rcu_read_unlock();
 }
 
 void ieee80211_stop_queue_by_reason(struct ieee80211_hw *hw, int queue,

net/mac80211/wme.c

@@ -45,21 +45,68 @@ static int wme_downgrade_ac(struct sk_buff *skb)
 
 
 /* Indicate which queue to use. */
-static u16 classify80211(struct ieee80211_local *local, struct sk_buff *skb)
+u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
+			   struct sk_buff *skb)
 {
-	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta = NULL;
+	u32 sta_flags = 0;
+	const u8 *ra = NULL;
+	bool qos = false;
 
-	if (!ieee80211_is_data(hdr->frame_control)) {
-		/* management frames go on AC_VO queue, but are sent
-		* without QoS control fields */
-		return 0;
+	if (local->hw.queues < 4 || skb->len < 6) {
+		skb->priority = 0; /* required for correct WPA/11i MIC */
+		return min_t(u16, local->hw.queues - 1,
+			     ieee802_1d_to_ac[skb->priority]);
 	}
 
-	if (0 /* injected */) {
-		/* use AC from radiotap */
+	rcu_read_lock();
+	switch (sdata->vif.type) {
+	case NL80211_IFTYPE_AP_VLAN:
+		rcu_read_lock();
+		sta = rcu_dereference(sdata->u.vlan.sta);
+		if (sta)
+			sta_flags = get_sta_flags(sta);
+		rcu_read_unlock();
+		if (sta)
+			break;
+	case NL80211_IFTYPE_AP:
+		ra = skb->data;
+		break;
+	case NL80211_IFTYPE_WDS:
+		ra = sdata->u.wds.remote_addr;
+		break;
+#ifdef CONFIG_MAC80211_MESH
+	case NL80211_IFTYPE_MESH_POINT:
+		/*
+		 * XXX: This is clearly broken ... but already was before,
+		 * because ieee80211_fill_mesh_addresses() would clear A1
+		 * except for multicast addresses.
+		 */
+		break;
+#endif
+	case NL80211_IFTYPE_STATION:
+		ra = sdata->u.mgd.bssid;
+		break;
+	case NL80211_IFTYPE_ADHOC:
+		ra = skb->data;
+		break;
+	default:
+		break;
 	}
 
-	if (!ieee80211_is_data_qos(hdr->frame_control)) {
+	if (!sta && ra && !is_multicast_ether_addr(ra)) {
+		sta = sta_info_get(sdata, ra);
+		if (sta)
+			sta_flags = get_sta_flags(sta);
+	}
+
+	if (sta_flags & WLAN_STA_WME)
+		qos = true;
+
+	rcu_read_unlock();
+
+	if (!qos) {
 		skb->priority = 0; /* required for correct WPA/11i MIC */
 		return ieee802_1d_to_ac[skb->priority];
 	}
@@ -68,6 +115,12 @@ static u16 classify80211(struct ieee80211_local *local, struct sk_buff *skb)
 	 * data frame has */
 	skb->priority = cfg80211_classify8021d(skb);
 
+	return ieee80211_downgrade_queue(local, skb);
+}
+
+u16 ieee80211_downgrade_queue(struct ieee80211_local *local,
+			      struct sk_buff *skb)
+{
 	/* in case we are a client verify acm is not set for this ac */
 	while (unlikely(local->wmm_acm & BIT(skb->priority))) {
 		if (wme_downgrade_ac(skb)) {
@@ -85,24 +138,17 @@ static u16 classify80211(struct ieee80211_local *local, struct sk_buff *skb)
 	return ieee802_1d_to_ac[skb->priority];
 }
 
-void ieee80211_select_queue(struct ieee80211_local *local, struct sk_buff *skb)
+void ieee80211_set_qos_hdr(struct ieee80211_local *local, struct sk_buff *skb)
 {
-	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
-	u16 queue;
-	u8 tid;
+	struct ieee80211_hdr *hdr = (void *)skb->data;
 
-	queue = classify80211(local, skb);
-	if (unlikely(queue >= local->hw.queues))
-		queue = local->hw.queues - 1;
-
-	/*
-	 * Now we know the 1d priority, fill in the QoS header if
-	 * there is one (and we haven't done this before).
-	 */
+	/* Fill in the QoS header if there is one. */
 	if (ieee80211_is_data_qos(hdr->frame_control)) {
 		u8 *p = ieee80211_get_qos_ctl(hdr);
-		u8 ack_policy = 0;
+		u8 ack_policy = 0, tid;
+
 		tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
+
 		if (unlikely(local->wifi_wme_noack_test))
 			ack_policy |= QOS_CONTROL_ACK_POLICY_NOACK <<
 					QOS_CONTROL_ACK_POLICY_SHIFT;
@@ -110,6 +156,4 @@ void ieee80211_select_queue(struct ieee80211_local *local, struct sk_buff *skb)
 		*p++ = ack_policy | tid;
 		*p = 0;
 	}
-
-	skb_set_queue_mapping(skb, queue);
 }

net/mac80211/wme.h

@@ -20,7 +20,11 @@
 
 extern const int ieee802_1d_to_ac[8];
 
-void ieee80211_select_queue(struct ieee80211_local *local,
+u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
 			   struct sk_buff *skb);
+void ieee80211_set_qos_hdr(struct ieee80211_local *local, struct sk_buff *skb);
+u16 ieee80211_downgrade_queue(struct ieee80211_local *local,
+                              struct sk_buff *skb);
+
 
 #endif /* _WME_H */