xfrm: prefer secpath_set over secpath_dup

secpath_set is a wrapper for secpath_dup that will not perform
an allocation if the secpath attached to the skb has a reference count
of one, i.e., it doesn't need to be COW'ed.

Also, secpath_dup doesn't attach the secpath to the skb, it leaves
this to the caller.

Use secpath_set in places that immediately assign the return value to
skb.

This allows to remove skb->sp without touching these spots again.

secpath_dup can eventually be removed in followup patch.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/ixgbe/ixgbe_ipsec.c

@@ -1161,6 +1161,7 @@ void ixgbe_ipsec_rx(struct ixgbe_ring *rx_ring,
 	struct xfrm_state *xs = NULL;
 	struct ipv6hdr *ip6 = NULL;
 	struct iphdr *ip4 = NULL;
+	struct sec_path *sp;
 	void *daddr;
 	__be32 spi;
 	u8 *c_hdr;
@@ -1200,12 +1201,12 @@ void ixgbe_ipsec_rx(struct ixgbe_ring *rx_ring,
 	if (unlikely(!xs))
 		return;
 
-	skb->sp = secpath_dup(skb->sp);
-	if (unlikely(!skb->sp))
+	sp = secpath_set(skb);
+	if (unlikely(!sp))
 		return;
 
-	skb->sp->xvec[skb->sp->len++] = xs;
-	skb->sp->olen++;
+	sp->xvec[sp->len++] = xs;
+	sp->olen++;
 	xo = xfrm_offload(skb);
 	xo->flags = CRYPTO_DONE;
 	xo->status = CRYPTO_SUCCESS;

drivers/net/ethernet/intel/ixgbevf/ipsec.c

@@ -548,6 +548,7 @@ void ixgbevf_ipsec_rx(struct ixgbevf_ring *rx_ring,
 	struct xfrm_state *xs = NULL;
 	struct ipv6hdr *ip6 = NULL;
 	struct iphdr *ip4 = NULL;
+	struct sec_path *sp;
 	void *daddr;
 	__be32 spi;
 	u8 *c_hdr;
@@ -587,12 +588,12 @@ void ixgbevf_ipsec_rx(struct ixgbevf_ring *rx_ring,
 	if (unlikely(!xs))
 		return;
 
-	skb->sp = secpath_dup(skb->sp);
-	if (unlikely(!skb->sp))
+	sp = secpath_set(skb);
+	if (unlikely(!sp))
 		return;
 
-	skb->sp->xvec[skb->sp->len++] = xs;
-	skb->sp->olen++;
+	sp->xvec[sp->len++] = xs;
+	sp->olen++;
 	xo = xfrm_offload(skb);
 	xo->flags = CRYPTO_DONE;
 	xo->status = CRYPTO_SUCCESS;

drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec_rxtx.c

@@ -307,10 +307,11 @@ mlx5e_ipsec_build_sp(struct net_device *netdev, struct sk_buff *skb,
 	struct mlx5e_priv *priv = netdev_priv(netdev);
 	struct xfrm_offload *xo;
 	struct xfrm_state *xs;
+	struct sec_path *sp;
 	u32 sa_handle;
 
-	skb->sp = secpath_dup(skb->sp);
-	if (unlikely(!skb->sp)) {
+	sp = secpath_set(skb);
+	if (unlikely(!sp)) {
 		atomic64_inc(&priv->ipsec->sw_stats.ipsec_rx_drop_sp_alloc);
 		return NULL;
 	}
@@ -322,8 +323,9 @@ mlx5e_ipsec_build_sp(struct net_device *netdev, struct sk_buff *skb,
 		return NULL;
 	}
 
-	skb->sp->xvec[skb->sp->len++] = xs;
-	skb->sp->olen++;
+	sp = skb_sec_path(skb);
+	sp->xvec[sp->len++] = xs;
+	sp->olen++;
 
 	xo = xfrm_offload(skb);
 	xo->flags = CRYPTO_DONE;

net/xfrm/Kconfig

@@ -5,6 +5,7 @@ config XFRM
        bool
        depends on NET
        select GRO_CELLS
+       select SKB_EXTENSIONS
 
 config XFRM_OFFLOAD
        bool

net/xfrm/xfrm_output.c

@@ -218,19 +218,16 @@ int xfrm_output(struct sock *sk, struct sk_buff *skb)
 	if (xfrm_dev_offload_ok(skb, x)) {
 		struct sec_path *sp;
 
-		sp = secpath_dup(skb->sp);
+		sp = secpath_set(skb);
 		if (!sp) {
 			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 			kfree_skb(skb);
 			return -ENOMEM;
 		}
-		if (skb->sp)
-			secpath_put(skb->sp);
-		skb->sp = sp;
 		skb->encapsulation = 1;
 
 		sp->olen++;
-		sp->xvec[skb->sp->len++] = x;
+		sp->xvec[sp->len++] = x;
 		xfrm_state_hold(x);
 
 		if (skb_is_gso(skb)) {