Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c
index 0f1217b..4e42954 100644
--- a/drivers/net/wan/lapbether.c
+++ b/drivers/net/wan/lapbether.c
@@ -51,6 +51,8 @@
 	struct list_head	node;
 	struct net_device	*ethdev;	/* link to ethernet device */
 	struct net_device	*axdev;		/* lapbeth device (lapb#) */
+	bool			up;
+	spinlock_t		up_lock;	/* Protects "up" */
 };
 
 static LIST_HEAD(lapbeth_devices);
@@ -98,8 +100,9 @@
 	rcu_read_lock();
 	lapbeth = lapbeth_get_x25_dev(dev);
 	if (!lapbeth)
-		goto drop_unlock;
-	if (!netif_running(lapbeth->axdev))
+		goto drop_unlock_rcu;
+	spin_lock_bh(&lapbeth->up_lock);
+	if (!lapbeth->up)
 		goto drop_unlock;
 
 	len = skb->data[0] + skb->data[1] * 256;
@@ -114,11 +117,14 @@
 		goto drop_unlock;
 	}
 out:
+	spin_unlock_bh(&lapbeth->up_lock);
 	rcu_read_unlock();
 	return 0;
 drop_unlock:
 	kfree_skb(skb);
 	goto out;
+drop_unlock_rcu:
+	rcu_read_unlock();
 drop:
 	kfree_skb(skb);
 	return 0;
@@ -128,10 +134,12 @@
 {
 	unsigned char *ptr;
 
-	skb_push(skb, 1);
-
-	if (skb_cow(skb, 1))
+	if (skb_cow(skb, 1)) {
+		kfree_skb(skb);
 		return NET_RX_DROP;
+	}
+
+	skb_push(skb, 1);
 
 	ptr  = skb->data;
 	*ptr = X25_IFACE_DATA;
@@ -146,13 +154,17 @@
 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
 				      struct net_device *dev)
 {
+	struct lapbethdev *lapbeth = netdev_priv(dev);
 	int err;
 
-	/*
-	 * Just to be *really* sure not to send anything if the interface
-	 * is down, the ethernet device may have gone.
+	spin_lock_bh(&lapbeth->up_lock);
+	if (!lapbeth->up)
+		goto drop;
+
+	/* There should be a pseudo header of 1 byte added by upper layers.
+	 * Check to make sure it is there before reading it.
 	 */
-	if (!netif_running(dev))
+	if (skb->len < 1)
 		goto drop;
 
 	switch (skb->data[0]) {
@@ -177,6 +189,7 @@
 		goto drop;
 	}
 out:
+	spin_unlock_bh(&lapbeth->up_lock);
 	return NETDEV_TX_OK;
 drop:
 	kfree_skb(skb);
@@ -190,8 +203,6 @@
 	struct net_device *dev;
 	int size = skb->len;
 
-	skb->protocol = htons(ETH_P_X25);
-
 	ptr = skb_push(skb, 2);
 
 	*ptr++ = size % 256;
@@ -202,6 +213,10 @@
 
 	skb->dev = dev = lapbeth->ethdev;
 
+	skb->protocol = htons(ETH_P_DEC);
+
+	skb_reset_network_header(skb);
+
 	dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
 
 	dev_queue_xmit(skb);
@@ -266,6 +281,7 @@
  */
 static int lapbeth_open(struct net_device *dev)
 {
+	struct lapbethdev *lapbeth = netdev_priv(dev);
 	int err;
 
 	if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
@@ -273,15 +289,21 @@
 		return -ENODEV;
 	}
 
-	netif_start_queue(dev);
+	spin_lock_bh(&lapbeth->up_lock);
+	lapbeth->up = true;
+	spin_unlock_bh(&lapbeth->up_lock);
+
 	return 0;
 }
 
 static int lapbeth_close(struct net_device *dev)
 {
+	struct lapbethdev *lapbeth = netdev_priv(dev);
 	int err;
 
-	netif_stop_queue(dev);
+	spin_lock_bh(&lapbeth->up_lock);
+	lapbeth->up = false;
+	spin_unlock_bh(&lapbeth->up_lock);
 
 	if ((err = lapb_unregister(dev)) != LAPB_OK)
 		pr_err("lapb_unregister error: %d\n", err);
@@ -303,7 +325,7 @@
 	dev->netdev_ops	     = &lapbeth_netdev_ops;
 	dev->needs_free_netdev = true;
 	dev->type            = ARPHRD_X25;
-	dev->hard_header_len = 3;
+	dev->hard_header_len = 0;
 	dev->mtu             = 1000;
 	dev->addr_len        = 0;
 }
@@ -324,12 +346,25 @@
 	if (!ndev)
 		goto out;
 
+	/* When transmitting data:
+	 * first this driver removes a pseudo header of 1 byte,
+	 * then the lapb module prepends an LAPB header of at most 3 bytes,
+	 * then this driver prepends a length field of 2 bytes,
+	 * then the underlying Ethernet device prepends its own header.
+	 */
+	ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
+					   + dev->needed_headroom;
+	ndev->needed_tailroom = dev->needed_tailroom;
+
 	lapbeth = netdev_priv(ndev);
 	lapbeth->axdev = ndev;
 
 	dev_hold(dev);
 	lapbeth->ethdev = dev;
 
+	lapbeth->up = false;
+	spin_lock_init(&lapbeth->up_lock);
+
 	rc = -EIO;
 	if (register_netdevice(ndev))
 		goto fail;