net: skb->dst accessors

Define three accessors to get/set dst attached to a skb

struct dst_entry *skb_dst(const struct sk_buff *skb)

void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)

void skb_dst_drop(struct sk_buff *skb)
This one should replace occurrences of :
dst_release(skb->dst)
skb->dst = NULL;

Delete skb->dst field

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 19 insertions, 13 deletions

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index b4a1317..e0009c1 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -251,8 +251,7 @@ resume:
 	nf_reset(skb);
 
 	if (decaps) {
-		dst_release(skb->dst);
-		skb->dst = NULL;
+		skb_dst_drop(skb);
 		netif_rx(skb);
 		return 0;
 	} else {
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index c235597..b9fe131 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -22,7 +22,7 @@ static int xfrm_output2(struct sk_buff *skb);
 
 static int xfrm_state_check_space(struct xfrm_state *x, struct sk_buff *skb)
 {
-	struct dst_entry *dst = skb->dst;
+	struct dst_entry *dst = skb_dst(skb);
 	int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
 		- skb_headroom(skb);
 	int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
@@ -39,7 +39,7 @@ static int xfrm_state_check_space(struct xfrm_state *x, struct sk_buff *skb)
 
 static int xfrm_output_one(struct sk_buff *skb, int err)
 {
-	struct dst_entry *dst = skb->dst;
+	struct dst_entry *dst = skb_dst(skb);
 	struct xfrm_state *x = dst->xfrm;
 	struct net *net = xs_net(x);
 
@@ -94,12 +94,13 @@ resume:
 			goto error_nolock;
 		}
 
-		if (!(skb->dst = dst_pop(dst))) {
+		dst = dst_pop(dst);
+		if (!dst) {
 			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 			err = -EHOSTUNREACH;
 			goto error_nolock;
 		}
-		dst = skb->dst;
+		skb_dst_set(skb, dst);
 		x = dst->xfrm;
 	} while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 
@@ -119,16 +120,16 @@ int xfrm_output_resume(struct sk_buff *skb, int err)
 	while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 		nf_reset(skb);
 
-		err = skb->dst->ops->local_out(skb);
+		err = skb_dst(skb)->ops->local_out(skb);
 		if (unlikely(err != 1))
 			goto out;
 
-		if (!skb->dst->xfrm)
+		if (!skb_dst(skb)->xfrm)
 			return dst_output(skb);
 
-		err = nf_hook(skb->dst->ops->family,
+		err = nf_hook(skb_dst(skb)->ops->family,
 			      NF_INET_POST_ROUTING, skb,
-			      NULL, skb->dst->dev, xfrm_output2);
+			      NULL, skb_dst(skb)->dev, xfrm_output2);
 		if (unlikely(err != 1))
 			goto out;
 	}
@@ -179,7 +180,7 @@ static int xfrm_output_gso(struct sk_buff *skb)
 
 int xfrm_output(struct sk_buff *skb)
 {
-	struct net *net = dev_net(skb->dst->dev);
+	struct net *net = dev_net(skb_dst(skb)->dev);
 	int err;
 
 	if (skb_is_gso(skb))
@@ -202,7 +203,7 @@ int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 	struct xfrm_mode *inner_mode;
 	if (x->sel.family == AF_UNSPEC)
 		inner_mode = xfrm_ip2inner_mode(x,
-				xfrm_af2proto(skb->dst->ops->family));
+				xfrm_af2proto(skb_dst(skb)->ops->family));
 	else
 		inner_mode = x->inner_mode;
 
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 9c068ab..cb81ca3 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2027,6 +2027,8 @@ int __xfrm_route_forward(struct sk_buff *skb, unsigned short family)
 {
 	struct net *net = dev_net(skb->dev);
 	struct flowi fl;
+	struct dst_entry *dst;
+	int res;
 
 	if (xfrm_decode_session(skb, &fl, family) < 0) {
 		/* XXX: we should have something like FWDHDRERROR here. */
@@ -2034,7 +2036,11 @@ int __xfrm_route_forward(struct sk_buff *skb, unsigned short family)
 		return 0;
 	}
 
-	return xfrm_lookup(net, &skb->dst, &fl, NULL, 0) == 0;
+	dst = skb_dst(skb);
+
+	res = xfrm_lookup(net, &dst, &fl, NULL, 0) == 0;
+	skb_dst_set(skb, dst);
+	return res;
 }
 EXPORT_SYMBOL(__xfrm_route_forward);