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>

1 files changed, 70 insertions, 26 deletions

diff --git a/net/mac80211/wme.c b/net/mac80211/wme.c
index b19b7696f3a..34e6d02da77 100644
--- a/net/mac80211/wme.c
+++ b/net/mac80211/wme.c
@@ -44,22 +44,69 @@ 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)
+/* Indicate which queue to use. */
+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]);
+	}
+
+	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 (0 /* injected */) {
-		/* use AC from radiotap */
+	if (!sta && ra && !is_multicast_ether_addr(ra)) {
+		sta = sta_info_get(sdata, ra);
+		if (sta)
+			sta_flags = get_sta_flags(sta);
 	}
 
-	if (!ieee80211_is_data_qos(hdr->frame_control)) {
+	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;
-
-	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).
-	 */
+	struct ieee80211_hdr *hdr = (void *)skb->data;
+
+	/* 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);
 }