net: Add initial_ref arg to dst_alloc().

This allows avoiding multiple writes to the initial __refcnt.

The most simplest cases of wanting an initial reference of "1"
in ipv4 and ipv6 have been converted, the rest have been left
along and kept at the existing "0".

Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dst.h

@@ -352,7 +352,7 @@ static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 }
 
 extern int dst_discard(struct sk_buff *skb);
-extern void * dst_alloc(struct dst_ops * ops);
+extern void *dst_alloc(struct dst_ops * ops, int initial_ref);
 extern void __dst_free(struct dst_entry * dst);
 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 

net/core/dst.c

@@ -166,7 +166,7 @@ EXPORT_SYMBOL(dst_discard);
 
 const u32 dst_default_metrics[RTAX_MAX];
 
-void *dst_alloc(struct dst_ops *ops)
+void *dst_alloc(struct dst_ops *ops, int initial_ref)
 {
 	struct dst_entry *dst;
 
@@ -177,7 +177,7 @@ void *dst_alloc(struct dst_ops *ops)
 	dst = kmem_cache_zalloc(ops->kmem_cachep, GFP_ATOMIC);
 	if (!dst)
 		return NULL;
-	atomic_set(&dst->__refcnt, 0);
+	atomic_set(&dst->__refcnt, initial_ref);
 	dst->ops = ops;
 	dst->lastuse = jiffies;
 	dst->path = dst;

net/decnet/dn_route.c

@@ -1122,7 +1122,7 @@ make_route:
 	if (dev_out->flags & IFF_LOOPBACK)
 		flags |= RTCF_LOCAL;
 
-	rt = dst_alloc(&dn_dst_ops);
+	rt = dst_alloc(&dn_dst_ops, 0);
 	if (rt == NULL)
 		goto e_nobufs;
 
@@ -1383,7 +1383,7 @@ static int dn_route_input_slow(struct sk_buff *skb)
 	}
 
 make_route:
-	rt = dst_alloc(&dn_dst_ops);
+	rt = dst_alloc(&dn_dst_ops, 0);
 	if (rt == NULL)
 		goto e_nobufs;
 

net/ipv4/route.c

@@ -1818,12 +1818,10 @@ static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag)
 
 static struct rtable *rt_dst_alloc(bool nopolicy, bool noxfrm)
 {
-	struct rtable *rt = dst_alloc(&ipv4_dst_ops);
+	struct rtable *rt = dst_alloc(&ipv4_dst_ops, 1);
 	if (rt) {
 		rt->dst.obsolete = -1;
 
-		atomic_set(&rt->dst.__refcnt, 1);
-
 		rt->dst.flags = DST_HOST |
 			(nopolicy ? DST_NOPOLICY : 0) |
 			(noxfrm ? DST_NOXFRM : 0);
@@ -2679,12 +2677,11 @@ static int ipv4_dst_blackhole(struct net *net, struct rtable **rp, struct flowi
 {
 	struct rtable *ort = *rp;
 	struct rtable *rt = (struct rtable *)
-		dst_alloc(&ipv4_dst_blackhole_ops);
+		dst_alloc(&ipv4_dst_blackhole_ops, 1);
 
 	if (rt) {
 		struct dst_entry *new = &rt->dst;
 
-		atomic_set(&new->__refcnt, 1);
 		new->__use = 1;
 		new->input = dst_discard;
 		new->output = dst_discard;

net/ipv6/route.c

@@ -221,7 +221,7 @@ static struct rt6_info ip6_blk_hole_entry_template = {
 /* allocate dst with ip6_dst_ops */
 static inline struct rt6_info *ip6_dst_alloc(struct dst_ops *ops)
 {
-	return (struct rt6_info *)dst_alloc(ops);
+	return (struct rt6_info *)dst_alloc(ops, 0);
 }
 
 static void ip6_dst_destroy(struct dst_entry *dst)
@@ -873,13 +873,12 @@ int ip6_dst_blackhole(struct sock *sk, struct dst_entry **dstp, struct flowi *fl
 {
 	struct rt6_info *ort = (struct rt6_info *) *dstp;
 	struct rt6_info *rt = (struct rt6_info *)
-		dst_alloc(&ip6_dst_blackhole_ops);
+		dst_alloc(&ip6_dst_blackhole_ops, 1);
 	struct dst_entry *new = NULL;
 
 	if (rt) {
 		new = &rt->dst;
 
-		atomic_set(&new->__refcnt, 1);
 		new->__use = 1;
 		new->input = dst_discard;
 		new->output = dst_discard;

net/xfrm/xfrm_policy.c

@@ -1340,7 +1340,7 @@ static inline struct xfrm_dst *xfrm_alloc_dst(struct net *net, int family)
 	default:
 		BUG();
 	}
-	xdst = dst_alloc(dst_ops) ?: ERR_PTR(-ENOBUFS);
+	xdst = dst_alloc(dst_ops, 0) ?: ERR_PTR(-ENOBUFS);
 	xfrm_policy_put_afinfo(afinfo);
 
 	xdst->flo.ops = &xfrm_bundle_fc_ops;