1 files changed, 250 insertions, 104 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index dda490542..6f9df375c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -71,6 +71,7 @@
 #include <net/sock.h>
 #include <linux/seq_file.h>
 #include <linux/uio.h>
+#include <linux/skb_array.h>
 
 #include <asm/uaccess.h>
 
@@ -131,6 +132,17 @@ struct tap_filter {
 
 #define TUN_FLOW_EXPIRE (3 * HZ)
 
+struct tun_pcpu_stats {
+	u64 rx_packets;
+	u64 rx_bytes;
+	u64 tx_packets;
+	u64 tx_bytes;
+	struct u64_stats_sync syncp;
+	u32 rx_dropped;
+	u32 tx_dropped;
+	u32 rx_frame_errors;
+};
+
 /* A tun_file connects an open character device to a tuntap netdevice. It
  * also contains all socket related structures (except sock_fprog and tap_filter)
  * to serve as one transmit queue for tuntap device. The sock_fprog and
@@ -156,6 +168,7 @@ struct tun_file {
 	};
 	struct list_head next;
 	struct tun_struct *detached;
+	struct skb_array tx_array;
 };
 
 struct tun_flow_entry {
@@ -205,6 +218,7 @@ struct tun_struct {
 	struct list_head disabled;
 	void *security;
 	u32 flow_count;
+	struct tun_pcpu_stats __percpu *pcpu_stats;
 };
 
 #ifdef CONFIG_TUN_VNET_CROSS_LE
@@ -503,7 +517,11 @@ static struct tun_struct *tun_enable_queue(struct tun_file *tfile)
 
 static void tun_queue_purge(struct tun_file *tfile)
 {
-	skb_queue_purge(&tfile->sk.sk_receive_queue);
+	struct sk_buff *skb;
+
+	while ((skb = skb_array_consume(&tfile->tx_array)) != NULL)
+		kfree_skb(skb);
+
 	skb_queue_purge(&tfile->sk.sk_error_queue);
 }
 
@@ -548,6 +566,8 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
 			    tun->dev->reg_state == NETREG_REGISTERED)
 				unregister_netdevice(tun->dev);
 		}
+		if (tun)
+			skb_array_cleanup(&tfile->tx_array);
 		sock_put(&tfile->sk);
 	}
 }
@@ -601,6 +621,7 @@ static void tun_detach_all(struct net_device *dev)
 static int tun_attach(struct tun_struct *tun, struct file *file, bool skip_filter)
 {
 	struct tun_file *tfile = file->private_data;
+	struct net_device *dev = tun->dev;
 	int err;
 
 	err = security_tun_dev_attach(tfile->socket.sk, tun->security);
@@ -624,11 +645,19 @@ static int tun_attach(struct tun_struct *tun, struct file *file, bool skip_filte
 
 	/* Re-attach the filter to persist device */
 	if (!skip_filter && (tun->filter_attached == true)) {
-		err = __sk_attach_filter(&tun->fprog, tfile->socket.sk,
-					 lockdep_rtnl_is_held());
+		lock_sock(tfile->socket.sk);
+		err = sk_attach_filter(&tun->fprog, tfile->socket.sk);
+		release_sock(tfile->socket.sk);
 		if (!err)
 			goto out;
 	}
+
+	if (!tfile->detached &&
+	    skb_array_init(&tfile->tx_array, dev->tx_queue_len, GFP_KERNEL)) {
+		err = -ENOMEM;
+		goto out;
+	}
+
 	tfile->queue_index = tun->numqueues;
 	tfile->socket.sk->sk_shutdown &= ~RCV_SHUTDOWN;
 	rcu_assign_pointer(tfile->tun, tun);
@@ -823,7 +852,8 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (txq >= numqueues)
 		goto drop;
 
-	if (numqueues == 1) {
+#ifdef CONFIG_RPS
+	if (numqueues == 1 && static_key_false(&rps_needed)) {
 		/* Select queue was not called for the skbuff, so we extract the
 		 * RPS hash and save it into the flow_table here.
 		 */
@@ -838,6 +868,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
 				tun_flow_save_rps_rxhash(e, rxhash);
 		}
 	}
+#endif
 
 	tun_debug(KERN_INFO, tun, "tun_net_xmit %d\n", skb->len);
 
@@ -863,10 +894,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
 		goto drop;
 
-	if (skb->sk && sk_fullsock(skb->sk)) {
-		sock_tx_timestamp(skb->sk, &skb_shinfo(skb)->tx_flags);
-		sw_tx_timestamp(skb);
-	}
+	skb_tx_timestamp(skb);
 
 	/* Orphan the skb - required as we might hang on to it
 	 * for indefinite time.
@@ -875,8 +903,8 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	nf_reset(skb);
 
-	/* Enqueue packet */
-	skb_queue_tail(&tfile->socket.sk->sk_receive_queue, skb);
+	if (skb_array_produce(&tfile->tx_array, skb))
+		goto drop;
 
 	/* Notify and wake up reader process */
 	if (tfile->flags & TUN_FASYNC)
@@ -887,7 +915,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
 	return NETDEV_TX_OK;
 
 drop:
-	dev->stats.tx_dropped++;
+	this_cpu_inc(tun->pcpu_stats->tx_dropped);
 	skb_tx_error(skb);
 	kfree_skb(skb);
 	rcu_read_unlock();
@@ -950,6 +978,43 @@ static void tun_set_headroom(struct net_device *dev, int new_hr)
 	tun->align = new_hr;
 }
 
+static struct rtnl_link_stats64 *
+tun_net_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
+{
+	u32 rx_dropped = 0, tx_dropped = 0, rx_frame_errors = 0;
+	struct tun_struct *tun = netdev_priv(dev);
+	struct tun_pcpu_stats *p;
+	int i;
+
+	for_each_possible_cpu(i) {
+		u64 rxpackets, rxbytes, txpackets, txbytes;
+		unsigned int start;
+
+		p = per_cpu_ptr(tun->pcpu_stats, i);
+		do {
+			start = u64_stats_fetch_begin(&p->syncp);
+			rxpackets	= p->rx_packets;
+			rxbytes		= p->rx_bytes;
+			txpackets	= p->tx_packets;
+			txbytes		= p->tx_bytes;
+		} while (u64_stats_fetch_retry(&p->syncp, start));
+
+		stats->rx_packets	+= rxpackets;
+		stats->rx_bytes		+= rxbytes;
+		stats->tx_packets	+= txpackets;
+		stats->tx_bytes		+= txbytes;
+
+		/* u32 counters */
+		rx_dropped	+= p->rx_dropped;
+		rx_frame_errors	+= p->rx_frame_errors;
+		tx_dropped	+= p->tx_dropped;
+	}
+	stats->rx_dropped  = rx_dropped;
+	stats->rx_frame_errors = rx_frame_errors;
+	stats->tx_dropped = tx_dropped;
+	return stats;
+}
+
 static const struct net_device_ops tun_netdev_ops = {
 	.ndo_uninit		= tun_net_uninit,
 	.ndo_open		= tun_net_open,
@@ -962,6 +1027,7 @@ static const struct net_device_ops tun_netdev_ops = {
 	.ndo_poll_controller	= tun_poll_controller,
 #endif
 	.ndo_set_rx_headroom	= tun_set_headroom,
+	.ndo_get_stats64	= tun_net_get_stats64,
 };
 
 static const struct net_device_ops tap_netdev_ops = {
@@ -980,6 +1046,7 @@ static const struct net_device_ops tap_netdev_ops = {
 #endif
 	.ndo_features_check	= passthru_features_check,
 	.ndo_set_rx_headroom	= tun_set_headroom,
+	.ndo_get_stats64	= tun_net_get_stats64,
 };
 
 static void tun_flow_init(struct tun_struct *tun)
@@ -1052,7 +1119,7 @@ static unsigned int tun_chr_poll(struct file *file, poll_table *wait)
 
 	poll_wait(file, sk_sleep(sk), wait);
 
-	if (!skb_queue_empty(&sk->sk_receive_queue))
+	if (!skb_array_empty(&tfile->tx_array))
 		mask |= POLLIN | POLLRDNORM;
 
 	if (sock_writeable(sk) ||
@@ -1104,6 +1171,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 	size_t total_len = iov_iter_count(from);
 	size_t len = total_len, align = tun->align, linear;
 	struct virtio_net_hdr gso = { 0 };
+	struct tun_pcpu_stats *stats;
 	int good_linear;
 	int copylen;
 	bool zerocopy = false;
@@ -1178,7 +1246,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 	skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
 	if (IS_ERR(skb)) {
 		if (PTR_ERR(skb) != -EAGAIN)
-			tun->dev->stats.rx_dropped++;
+			this_cpu_inc(tun->pcpu_stats->rx_dropped);
 		return PTR_ERR(skb);
 	}
 
@@ -1193,18 +1261,16 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 	}
 
 	if (err) {
-		tun->dev->stats.rx_dropped++;
+		this_cpu_inc(tun->pcpu_stats->rx_dropped);
 		kfree_skb(skb);
 		return -EFAULT;
 	}
 
-	if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
-		if (!skb_partial_csum_set(skb, tun16_to_cpu(tun, gso.csum_start),
-					  tun16_to_cpu(tun, gso.csum_offset))) {
-			tun->dev->stats.rx_frame_errors++;
-			kfree_skb(skb);
-			return -EINVAL;
-		}
+	err = virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun));
+	if (err) {
+		this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
+		kfree_skb(skb);
+		return -EINVAL;
 	}
 
 	switch (tun->flags & TUN_TYPE_MASK) {
@@ -1218,7 +1284,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 				pi.proto = htons(ETH_P_IPV6);
 				break;
 			default:
-				tun->dev->stats.rx_dropped++;
+				this_cpu_inc(tun->pcpu_stats->rx_dropped);
 				kfree_skb(skb);
 				return -EINVAL;
 			}
@@ -1233,39 +1299,6 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 		break;
 	}
 
-	if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
-		pr_debug("GSO!\n");
-		switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
-		case VIRTIO_NET_HDR_GSO_TCPV4:
-			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
-			break;
-		case VIRTIO_NET_HDR_GSO_TCPV6:
-			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
-			break;
-		case VIRTIO_NET_HDR_GSO_UDP:
-			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
-			break;
-		default:
-			tun->dev->stats.rx_frame_errors++;
-			kfree_skb(skb);
-			return -EINVAL;
-		}
-
-		if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
-			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
-
-		skb_shinfo(skb)->gso_size = tun16_to_cpu(tun, gso.gso_size);
-		if (skb_shinfo(skb)->gso_size == 0) {
-			tun->dev->stats.rx_frame_errors++;
-			kfree_skb(skb);
-			return -EINVAL;
-		}
-
-		/* Header must be checked, and gso_segs computed. */
-		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
-		skb_shinfo(skb)->gso_segs = 0;
-	}
-
 	/* copy skb_ubuf_info for callback when skb has no error */
 	if (zerocopy) {
 		skb_shinfo(skb)->destructor_arg = msg_control;
@@ -1279,8 +1312,12 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 	rxhash = skb_get_hash(skb);
 	netif_rx_ni(skb);
 
-	tun->dev->stats.rx_packets++;
-	tun->dev->stats.rx_bytes += len;
+	stats = get_cpu_ptr(tun->pcpu_stats);
+	u64_stats_update_begin(&stats->syncp);
+	stats->rx_packets++;
+	stats->rx_bytes += len;
+	u64_stats_update_end(&stats->syncp);
+	put_cpu_ptr(stats);
 
 	tun_flow_update(tun, rxhash, tfile);
 	return total_len;
@@ -1309,6 +1346,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 			    struct iov_iter *iter)
 {
 	struct tun_pi pi = { 0, skb->protocol };
+	struct tun_pcpu_stats *stats;
 	ssize_t total;
 	int vlan_offset = 0;
 	int vlan_hlen = 0;
@@ -1338,46 +1376,26 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 
 	if (vnet_hdr_sz) {
 		struct virtio_net_hdr gso = { 0 }; /* no info leak */
+		int ret;
+
 		if (iov_iter_count(iter) < vnet_hdr_sz)
 			return -EINVAL;
 
-		if (skb_is_gso(skb)) {
+		ret = virtio_net_hdr_from_skb(skb, &gso,
+					      tun_is_little_endian(tun));
+		if (ret) {
 			struct skb_shared_info *sinfo = skb_shinfo(skb);
-
-			/* This is a hint as to how much should be linear. */
-			gso.hdr_len = cpu_to_tun16(tun, skb_headlen(skb));
-			gso.gso_size = cpu_to_tun16(tun, sinfo->gso_size);
-			if (sinfo->gso_type & SKB_GSO_TCPV4)
-				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
-			else if (sinfo->gso_type & SKB_GSO_TCPV6)
-				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
-			else if (sinfo->gso_type & SKB_GSO_UDP)
-				gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
-			else {
-				pr_err("unexpected GSO type: "
-				       "0x%x, gso_size %d, hdr_len %d\n",
-				       sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
-				       tun16_to_cpu(tun, gso.hdr_len));
-				print_hex_dump(KERN_ERR, "tun: ",
-					       DUMP_PREFIX_NONE,
-					       16, 1, skb->head,
-					       min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
-				WARN_ON_ONCE(1);
-				return -EINVAL;
-			}
-			if (sinfo->gso_type & SKB_GSO_TCP_ECN)
-				gso.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
-		} else
-			gso.gso_type = VIRTIO_NET_HDR_GSO_NONE;
-
-		if (skb->ip_summed == CHECKSUM_PARTIAL) {
-			gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-			gso.csum_start = cpu_to_tun16(tun, skb_checksum_start_offset(skb) +
-						      vlan_hlen);
-			gso.csum_offset = cpu_to_tun16(tun, skb->csum_offset);
-		} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
-			gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
-		} /* else everything is zero */
+			pr_err("unexpected GSO type: "
+			       "0x%x, gso_size %d, hdr_len %d\n",
+			       sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
+			       tun16_to_cpu(tun, gso.hdr_len));
+			print_hex_dump(KERN_ERR, "tun: ",
+				       DUMP_PREFIX_NONE,
+				       16, 1, skb->head,
+				       min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
+			WARN_ON_ONCE(1);
+			return -EINVAL;
+		}
 
 		if (copy_to_iter(&gso, sizeof(gso), iter) != sizeof(gso))
 			return -EFAULT;
@@ -1409,28 +1427,74 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 	skb_copy_datagram_iter(skb, vlan_offset, iter, skb->len - vlan_offset);
 
 done:
-	tun->dev->stats.tx_packets++;
-	tun->dev->stats.tx_bytes += skb->len + vlan_hlen;
+	/* caller is in process context, */
+	stats = get_cpu_ptr(tun->pcpu_stats);
+	u64_stats_update_begin(&stats->syncp);
+	stats->tx_packets++;
+	stats->tx_bytes += skb->len + vlan_hlen;
+	u64_stats_update_end(&stats->syncp);
+	put_cpu_ptr(tun->pcpu_stats);
 
 	return total;
 }
 
+static struct sk_buff *tun_ring_recv(struct tun_file *tfile, int noblock,
+				     int *err)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	struct sk_buff *skb = NULL;
+	int error = 0;
+
+	skb = skb_array_consume(&tfile->tx_array);
+	if (skb)
+		goto out;
+	if (noblock) {
+		error = -EAGAIN;
+		goto out;
+	}
+
+	add_wait_queue(&tfile->wq.wait, &wait);
+	current->state = TASK_INTERRUPTIBLE;
+
+	while (1) {
+		skb = skb_array_consume(&tfile->tx_array);
+		if (skb)
+			break;
+		if (signal_pending(current)) {
+			error = -ERESTARTSYS;
+			break;
+		}
+		if (tfile->socket.sk->sk_shutdown & RCV_SHUTDOWN) {
+			error = -EFAULT;
+			break;
+		}
+
+		schedule();
+	}
+
+	current->state = TASK_RUNNING;
+	remove_wait_queue(&tfile->wq.wait, &wait);
+
+out:
+	*err = error;
+	return skb;
+}
+
 static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
 			   struct iov_iter *to,
 			   int noblock)
 {
 	struct sk_buff *skb;
 	ssize_t ret;
-	int peeked, err, off = 0;
+	int err;
 
 	tun_debug(KERN_INFO, tun, "tun_do_read\n");
 
 	if (!iov_iter_count(to))
 		return 0;
 
-	/* Read frames from queue */
-	skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
-				  &peeked, &off, &err);
+	/* Read frames from ring */
+	skb = tun_ring_recv(tfile, noblock, &err);
 	if (!skb)
 		return err;
 
@@ -1465,6 +1529,7 @@ static void tun_free_netdev(struct net_device *dev)
 	struct tun_struct *tun = netdev_priv(dev);
 
 	BUG_ON(!(list_empty(&tun->disabled)));
+	free_percpu(tun->pcpu_stats);
 	tun_flow_uninit(tun);
 	security_tun_dev_free_security(tun->security);
 	free_netdev(dev);
@@ -1562,8 +1627,25 @@ out:
 	return ret;
 }
 
+static int tun_peek_len(struct socket *sock)
+{
+	struct tun_file *tfile = container_of(sock, struct tun_file, socket);
+	struct tun_struct *tun;
+	int ret = 0;
+
+	tun = __tun_get(tfile);
+	if (!tun)
+		return 0;
+
+	ret = skb_array_peek_len(&tfile->tx_array);
+	tun_put(tun);
+
+	return ret;
+}
+
 /* Ops structure to mimic raw sockets with tun */
 static const struct proto_ops tun_socket_ops = {
+	.peek_len = tun_peek_len,
 	.sendmsg = tun_sendmsg,
 	.recvmsg = tun_recvmsg,
 };
@@ -1713,11 +1795,17 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 		tun->filter_attached = false;
 		tun->sndbuf = tfile->socket.sk->sk_sndbuf;
 
+		tun->pcpu_stats = netdev_alloc_pcpu_stats(struct tun_pcpu_stats);
+		if (!tun->pcpu_stats) {
+			err = -ENOMEM;
+			goto err_free_dev;
+		}
+
 		spin_lock_init(&tun->lock);
 
 		err = security_tun_dev_alloc_security(&tun->security);
 		if (err < 0)
-			goto err_free_dev;
+			goto err_free_stat;
 
 		tun_net_init(dev);
 		tun_flow_init(tun);
@@ -1725,7 +1813,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 		dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
 				   TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX |
 				   NETIF_F_HW_VLAN_STAG_TX;
-		dev->features = dev->hw_features;
+		dev->features = dev->hw_features | NETIF_F_LLTX;
 		dev->vlan_features = dev->features &
 				     ~(NETIF_F_HW_VLAN_CTAG_TX |
 				       NETIF_F_HW_VLAN_STAG_TX);
@@ -1761,6 +1849,8 @@ err_detach:
 err_free_flow:
 	tun_flow_uninit(tun);
 	security_tun_dev_free_security(tun->security);
+err_free_stat:
+	free_percpu(tun->pcpu_stats);
 err_free_dev:
 	free_netdev(dev);
 	return err;
@@ -1823,7 +1913,9 @@ static void tun_detach_filter(struct tun_struct *tun, int n)
 
 	for (i = 0; i < n; i++) {
 		tfile = rtnl_dereference(tun->tfiles[i]);
-		__sk_detach_filter(tfile->socket.sk, lockdep_rtnl_is_held());
+		lock_sock(tfile->socket.sk);
+		sk_detach_filter(tfile->socket.sk);
+		release_sock(tfile->socket.sk);
 	}
 
 	tun->filter_attached = false;
@@ -1836,8 +1928,9 @@ static int tun_attach_filter(struct tun_struct *tun)
 
 	for (i = 0; i < tun->numqueues; i++) {
 		tfile = rtnl_dereference(tun->tfiles[i]);
-		ret = __sk_attach_filter(&tun->fprog, tfile->socket.sk,
-					 lockdep_rtnl_is_held());
+		lock_sock(tfile->socket.sk);
+		ret = sk_attach_filter(&tun->fprog, tfile->socket.sk);
+		release_sock(tfile->socket.sk);
 		if (ret) {
 			tun_detach_filter(tun, i);
 			return ret;
@@ -2374,6 +2467,56 @@ static const struct ethtool_ops tun_ethtool_ops = {
 	.get_ts_info	= ethtool_op_get_ts_info,
 };
 
+static int tun_queue_resize(struct tun_struct *tun)
+{
+	struct net_device *dev = tun->dev;
+	struct tun_file *tfile;
+	struct skb_array **arrays;
+	int n = tun->numqueues + tun->numdisabled;
+	int ret, i;
+
+	arrays = kmalloc(sizeof *arrays * n, GFP_KERNEL);
+	if (!arrays)
+		return -ENOMEM;
+
+	for (i = 0; i < tun->numqueues; i++) {
+		tfile = rtnl_dereference(tun->tfiles[i]);
+		arrays[i] = &tfile->tx_array;
+	}
+	list_for_each_entry(tfile, &tun->disabled, next)
+		arrays[i++] = &tfile->tx_array;
+
+	ret = skb_array_resize_multiple(arrays, n,
+					dev->tx_queue_len, GFP_KERNEL);
+
+	kfree(arrays);
+	return ret;
+}
+
+static int tun_device_event(struct notifier_block *unused,
+			    unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct tun_struct *tun = netdev_priv(dev);
+
+	if (dev->rtnl_link_ops != &tun_link_ops)
+		return NOTIFY_DONE;
+
+	switch (event) {
+	case NETDEV_CHANGE_TX_QUEUE_LEN:
+		if (tun_queue_resize(tun))
+			return NOTIFY_BAD;
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block tun_notifier_block __read_mostly = {
+	.notifier_call	= tun_device_event,
+};
 
 static int __init tun_init(void)
 {
@@ -2393,6 +2536,8 @@ static int __init tun_init(void)
 		pr_err("Can't register misc device %d\n", TUN_MINOR);
 		goto err_misc;
 	}
+
+	register_netdevice_notifier(&tun_notifier_block);
 	return  0;
 err_misc:
 	rtnl_link_unregister(&tun_link_ops);
@@ -2404,6 +2549,7 @@ static void tun_cleanup(void)
 {
 	misc_deregister(&tun_miscdev);
 	rtnl_link_unregister(&tun_link_ops);
+	unregister_netdevice_notifier(&tun_notifier_block);
 }
 
 /* Get an underlying socket object from tun file.  Returns error unless file is