From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Mon, 13 Jan 2020 18:42:28 -0500
Subject: net: xfrm: use skb_list_walk_safe helper for gso segments
Patch-mainline: v5.6-rc1
Git-commit: c3b18e0d925439043b5887c9a6129ff2ffaf58b0
References: bsc#1176447

This is converts xfrm segment iteration to use the new function, keeping
the flow of the existing code as intact as possible. One case is very
straight-forward, whereas the other case has some more subtle code that
likes to peak at ->next and relink skbs. By keeping the variables the
same as before, we can upgrade this code with minimal surgery required.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/xfrm/xfrm_device.c |   15 ++++-----------
 net/xfrm/xfrm_output.c |    9 +++------
 2 files changed, 7 insertions(+), 17 deletions(-)

--- a/net/xfrm/xfrm_device.c
+++ b/net/xfrm/xfrm_device.c
@@ -78,7 +78,7 @@ struct sk_buff *validate_xmit_xfrm(struc
 	int err;
 	unsigned long flags;
 	struct xfrm_state *x;
-	struct sk_buff *skb2;
+	struct sk_buff *skb2, *nskb;
 	struct softnet_data *sd;
 	netdev_features_t esp_features = features;
 	struct xfrm_offload *xo = xfrm_offload(skb);
@@ -148,11 +148,7 @@ struct sk_buff *validate_xmit_xfrm(struc
 		return skb;
 	}
 
-	skb2 = skb;
-
-	do {
-		struct sk_buff *nskb = skb2->next;
-
+	skb_list_walk_safe(skb, skb2, nskb) {
 		esp_features |= skb->dev->gso_partial_features;
 		skb_mark_not_on_list(skb2);
 
@@ -176,14 +172,11 @@ struct sk_buff *validate_xmit_xfrm(struc
 			if (!skb)
 				return NULL;
 
-			goto skip_push;
+			continue;
 		}
 
 		skb_push(skb2, skb2->data - skb_mac_header(skb2));
-
-skip_push:
-		skb2 = nskb;
-	} while (skb2);
+	}
 
 	return skb;
 }
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -533,7 +533,7 @@ static int xfrm_output2(struct net *net,
 
 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
-	struct sk_buff *segs;
+	struct sk_buff *segs, *nskb;
 
 	BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
 	BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET);
@@ -544,8 +544,7 @@ static int xfrm_output_gso(struct net *n
 	if (segs == NULL)
 		return -EINVAL;
 
-	do {
-		struct sk_buff *nskb = segs->next;
+	skb_list_walk_safe(segs, segs, nskb) {
 		int err;
 
 		skb_mark_not_on_list(segs);
@@ -555,9 +554,7 @@ static int xfrm_output_gso(struct net *n
 			kfree_skb_list(nskb);
 			return err;
 		}
-
-		segs = nskb;
-	} while (segs);
+	}
 
 	return 0;
 }