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, 37 insertions, 2 deletions

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 80c16f6..c261cdb 100644
--- a/net/mac80211/iface.c
+++ b/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));