+static struct dst_ops md_dst_ops = {
+ .family = AF_UNSPEC,
+};
+
+static int dst_md_discard_sk(struct sock *sk, struct sk_buff *skb)
+{
+ WARN_ONCE(1, "Attempting to call output on metadata dst\n");
+ kfree_skb(skb);
+ return 0;
+}
+
+static int dst_md_discard(struct sk_buff *skb)
+{
+ WARN_ONCE(1, "Attempting to call input on metadata dst\n");
+ kfree_skb(skb);
+ return 0;
+}
+
+static void __metadata_dst_init(struct metadata_dst *md_dst, u8 optslen)
+{
+ struct dst_entry *dst;
+
+ dst = &md_dst->dst;
+ dst_init(dst, &md_dst_ops, NULL, 1, DST_OBSOLETE_NONE,
+ DST_METADATA | DST_NOCACHE | DST_NOCOUNT);
+
+ dst->input = dst_md_discard;
+ dst->output = dst_md_discard_sk;
+
+ memset(dst + 1, 0, sizeof(*md_dst) + optslen - sizeof(*dst));
+ md_dst->opts_len = optslen;
+}
+
+struct metadata_dst *metadata_dst_alloc(u8 optslen, gfp_t flags)
+{
+ struct metadata_dst *md_dst;
+
+ md_dst = kmalloc(sizeof(*md_dst) + optslen, flags);
+ if (!md_dst)
+ return NULL;
+
+ __metadata_dst_init(md_dst, optslen);
+
+ return md_dst;
+}
+EXPORT_SYMBOL_GPL(metadata_dst_alloc);
+
+struct metadata_dst __percpu *metadata_dst_alloc_percpu(u8 optslen, gfp_t flags)
+{
+ int cpu;
+ struct metadata_dst __percpu *md_dst;
+
+ md_dst = __alloc_percpu_gfp(sizeof(struct metadata_dst) + optslen,
+ __alignof__(struct metadata_dst), flags);
+ if (!md_dst)
+ return NULL;
+
+ for_each_possible_cpu(cpu)
+ __metadata_dst_init(per_cpu_ptr(md_dst, cpu), optslen);
+
+ return md_dst;
+}
+EXPORT_SYMBOL_GPL(metadata_dst_alloc_percpu);
+