Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 3621e05..0020b2e 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -136,12 +136,12 @@
 
 static u16 frag_get_pending_idx(skb_frag_t *frag)
 {
-	return (u16)frag->page_offset;
+	return (u16)skb_frag_off(frag);
 }
 
 static void frag_set_pending_idx(skb_frag_t *frag, u16 pending_idx)
 {
-	frag->page_offset = pending_idx;
+	skb_frag_off_set(frag, pending_idx);
 }
 
 static inline pending_ring_idx_t pending_index(unsigned i)
@@ -925,6 +925,7 @@
 			skb_shinfo(skb)->nr_frags = MAX_SKB_FRAGS;
 			nskb = xenvif_alloc_skb(0);
 			if (unlikely(nskb == NULL)) {
+				skb_shinfo(skb)->nr_frags = 0;
 				kfree_skb(skb);
 				xenvif_tx_err(queue, &txreq, extra_count, idx);
 				if (net_ratelimit())
@@ -940,6 +941,7 @@
 
 			if (xenvif_set_skb_gso(queue->vif, skb, gso)) {
 				/* Failure in xenvif_set_skb_gso is fatal. */
+				skb_shinfo(skb)->nr_frags = 0;
 				kfree_skb(skb);
 				kfree_skb(nskb);
 				break;
@@ -1055,7 +1057,7 @@
 			int j;
 			skb->truesize += skb->data_len;
 			for (j = 0; j < i; j++)
-				put_page(frags[j].page.p);
+				put_page(skb_frag_page(&frags[j]));
 			return -ENOMEM;
 		}
 
@@ -1067,16 +1069,11 @@
 			BUG();
 
 		offset += len;
-		frags[i].page.p = page;
-		frags[i].page_offset = 0;
+		__skb_frag_set_page(&frags[i], page);
+		skb_frag_off_set(&frags[i], 0);
 		skb_frag_size_set(&frags[i], len);
 	}
 
-	/* Copied all the bits from the frag list -- free it. */
-	skb_frag_list_init(skb);
-	xenvif_skb_zerocopy_prepare(queue, nskb);
-	kfree_skb(nskb);
-
 	/* Release all the original (foreign) frags. */
 	for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
 		skb_frag_unref(skb, f);
@@ -1145,6 +1142,8 @@
 		xenvif_fill_frags(queue, skb);
 
 		if (unlikely(skb_has_frag_list(skb))) {
+			struct sk_buff *nskb = skb_shinfo(skb)->frag_list;
+			xenvif_skb_zerocopy_prepare(queue, nskb);
 			if (xenvif_handle_frag_list(queue, skb)) {
 				if (net_ratelimit())
 					netdev_err(queue->vif->dev,
@@ -1153,6 +1152,9 @@
 				kfree_skb(skb);
 				continue;
 			}
+			/* Copied all the bits from the frag list -- free it. */
+			skb_frag_list_init(skb);
+			kfree_skb(nskb);
 		}
 
 		skb->dev      = queue->vif->dev;
@@ -1169,15 +1171,24 @@
 			continue;
 		}
 
-		skb_probe_transport_header(skb, 0);
+		skb_probe_transport_header(skb);
 
 		/* If the packet is GSO then we will have just set up the
 		 * transport header offset in checksum_setup so it's now
 		 * straightforward to calculate gso_segs.
 		 */
 		if (skb_is_gso(skb)) {
-			int mss = skb_shinfo(skb)->gso_size;
-			int hdrlen = skb_transport_header(skb) -
+			int mss, hdrlen;
+
+			/* GSO implies having the L4 header. */
+			WARN_ON_ONCE(!skb_transport_header_was_set(skb));
+			if (unlikely(!skb_transport_header_was_set(skb))) {
+				kfree_skb(skb);
+				continue;
+			}
+
+			mss = skb_shinfo(skb)->gso_size;
+			hdrlen = skb_transport_header(skb) -
 				skb_mac_header(skb) +
 				tcp_hdrlen(skb);
 
@@ -1644,9 +1655,6 @@
 
 #ifdef CONFIG_DEBUG_FS
 	xen_netback_dbg_root = debugfs_create_dir("xen-netback", NULL);
-	if (IS_ERR_OR_NULL(xen_netback_dbg_root))
-		pr_warn("Init of debugfs returned %ld!\n",
-			PTR_ERR(xen_netback_dbg_root));
 #endif /* CONFIG_DEBUG_FS */
 
 	return 0;
@@ -1660,8 +1668,7 @@
 static void __exit netback_fini(void)
 {
 #ifdef CONFIG_DEBUG_FS
-	if (!IS_ERR_OR_NULL(xen_netback_dbg_root))
-		debugfs_remove_recursive(xen_netback_dbg_root);
+	debugfs_remove_recursive(xen_netback_dbg_root);
 #endif /* CONFIG_DEBUG_FS */
 	xenvif_xenbus_fini();
 }