v4.19.13 snapshot.
diff --git a/net/ipv4/ipmr_base.c b/net/ipv4/ipmr_base.c
new file mode 100644
index 0000000..eab8cd5
--- /dev/null
+++ b/net/ipv4/ipmr_base.c
@@ -0,0 +1,369 @@
+/* Linux multicast routing support
+ * Common logic shared by IPv4 [ipmr] and IPv6 [ip6mr] implementation
+ */
+
+#include <linux/rhashtable.h>
+#include <linux/mroute_base.h>
+
+/* Sets everything common except 'dev', since that is done under locking */
+void vif_device_init(struct vif_device *v,
+		     struct net_device *dev,
+		     unsigned long rate_limit,
+		     unsigned char threshold,
+		     unsigned short flags,
+		     unsigned short get_iflink_mask)
+{
+	v->dev = NULL;
+	v->bytes_in = 0;
+	v->bytes_out = 0;
+	v->pkt_in = 0;
+	v->pkt_out = 0;
+	v->rate_limit = rate_limit;
+	v->flags = flags;
+	v->threshold = threshold;
+	if (v->flags & get_iflink_mask)
+		v->link = dev_get_iflink(dev);
+	else
+		v->link = dev->ifindex;
+}
+EXPORT_SYMBOL(vif_device_init);
+
+struct mr_table *
+mr_table_alloc(struct net *net, u32 id,
+	       struct mr_table_ops *ops,
+	       void (*expire_func)(struct timer_list *t),
+	       void (*table_set)(struct mr_table *mrt,
+				 struct net *net))
+{
+	struct mr_table *mrt;
+	int err;
+
+	mrt = kzalloc(sizeof(*mrt), GFP_KERNEL);
+	if (!mrt)
+		return ERR_PTR(-ENOMEM);
+	mrt->id = id;
+	write_pnet(&mrt->net, net);
+
+	mrt->ops = *ops;
+	err = rhltable_init(&mrt->mfc_hash, mrt->ops.rht_params);
+	if (err) {
+		kfree(mrt);
+		return ERR_PTR(err);
+	}
+	INIT_LIST_HEAD(&mrt->mfc_cache_list);
+	INIT_LIST_HEAD(&mrt->mfc_unres_queue);
+
+	timer_setup(&mrt->ipmr_expire_timer, expire_func, 0);
+
+	mrt->mroute_reg_vif_num = -1;
+	table_set(mrt, net);
+	return mrt;
+}
+EXPORT_SYMBOL(mr_table_alloc);
+
+void *mr_mfc_find_parent(struct mr_table *mrt, void *hasharg, int parent)
+{
+	struct rhlist_head *tmp, *list;
+	struct mr_mfc *c;
+
+	list = rhltable_lookup(&mrt->mfc_hash, hasharg, *mrt->ops.rht_params);
+	rhl_for_each_entry_rcu(c, tmp, list, mnode)
+		if (parent == -1 || parent == c->mfc_parent)
+			return c;
+
+	return NULL;
+}
+EXPORT_SYMBOL(mr_mfc_find_parent);
+
+void *mr_mfc_find_any_parent(struct mr_table *mrt, int vifi)
+{
+	struct rhlist_head *tmp, *list;
+	struct mr_mfc *c;
+
+	list = rhltable_lookup(&mrt->mfc_hash, mrt->ops.cmparg_any,
+			       *mrt->ops.rht_params);
+	rhl_for_each_entry_rcu(c, tmp, list, mnode)
+		if (c->mfc_un.res.ttls[vifi] < 255)
+			return c;
+
+	return NULL;
+}
+EXPORT_SYMBOL(mr_mfc_find_any_parent);
+
+void *mr_mfc_find_any(struct mr_table *mrt, int vifi, void *hasharg)
+{
+	struct rhlist_head *tmp, *list;
+	struct mr_mfc *c, *proxy;
+
+	list = rhltable_lookup(&mrt->mfc_hash, hasharg, *mrt->ops.rht_params);
+	rhl_for_each_entry_rcu(c, tmp, list, mnode) {
+		if (c->mfc_un.res.ttls[vifi] < 255)
+			return c;
+
+		/* It's ok if the vifi is part of the static tree */
+		proxy = mr_mfc_find_any_parent(mrt, c->mfc_parent);
+		if (proxy && proxy->mfc_un.res.ttls[vifi] < 255)
+			return c;
+	}
+
+	return mr_mfc_find_any_parent(mrt, vifi);
+}
+EXPORT_SYMBOL(mr_mfc_find_any);
+
+#ifdef CONFIG_PROC_FS
+void *mr_vif_seq_idx(struct net *net, struct mr_vif_iter *iter, loff_t pos)
+{
+	struct mr_table *mrt = iter->mrt;
+
+	for (iter->ct = 0; iter->ct < mrt->maxvif; ++iter->ct) {
+		if (!VIF_EXISTS(mrt, iter->ct))
+			continue;
+		if (pos-- == 0)
+			return &mrt->vif_table[iter->ct];
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(mr_vif_seq_idx);
+
+void *mr_vif_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct mr_vif_iter *iter = seq->private;
+	struct net *net = seq_file_net(seq);
+	struct mr_table *mrt = iter->mrt;
+
+	++*pos;
+	if (v == SEQ_START_TOKEN)
+		return mr_vif_seq_idx(net, iter, 0);
+
+	while (++iter->ct < mrt->maxvif) {
+		if (!VIF_EXISTS(mrt, iter->ct))
+			continue;
+		return &mrt->vif_table[iter->ct];
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(mr_vif_seq_next);
+
+void *mr_mfc_seq_idx(struct net *net,
+		     struct mr_mfc_iter *it, loff_t pos)
+{
+	struct mr_table *mrt = it->mrt;
+	struct mr_mfc *mfc;
+
+	rcu_read_lock();
+	it->cache = &mrt->mfc_cache_list;
+	list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list)
+		if (pos-- == 0)
+			return mfc;
+	rcu_read_unlock();
+
+	spin_lock_bh(it->lock);
+	it->cache = &mrt->mfc_unres_queue;
+	list_for_each_entry(mfc, it->cache, list)
+		if (pos-- == 0)
+			return mfc;
+	spin_unlock_bh(it->lock);
+
+	it->cache = NULL;
+	return NULL;
+}
+EXPORT_SYMBOL(mr_mfc_seq_idx);
+
+void *mr_mfc_seq_next(struct seq_file *seq, void *v,
+		      loff_t *pos)
+{
+	struct mr_mfc_iter *it = seq->private;
+	struct net *net = seq_file_net(seq);
+	struct mr_table *mrt = it->mrt;
+	struct mr_mfc *c = v;
+
+	++*pos;
+
+	if (v == SEQ_START_TOKEN)
+		return mr_mfc_seq_idx(net, seq->private, 0);
+
+	if (c->list.next != it->cache)
+		return list_entry(c->list.next, struct mr_mfc, list);
+
+	if (it->cache == &mrt->mfc_unres_queue)
+		goto end_of_list;
+
+	/* exhausted cache_array, show unresolved */
+	rcu_read_unlock();
+	it->cache = &mrt->mfc_unres_queue;
+
+	spin_lock_bh(it->lock);
+	if (!list_empty(it->cache))
+		return list_first_entry(it->cache, struct mr_mfc, list);
+
+end_of_list:
+	spin_unlock_bh(it->lock);
+	it->cache = NULL;
+
+	return NULL;
+}
+EXPORT_SYMBOL(mr_mfc_seq_next);
+#endif
+
+int mr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
+		   struct mr_mfc *c, struct rtmsg *rtm)
+{
+	struct rta_mfc_stats mfcs;
+	struct nlattr *mp_attr;
+	struct rtnexthop *nhp;
+	unsigned long lastuse;
+	int ct;
+
+	/* If cache is unresolved, don't try to parse IIF and OIF */
+	if (c->mfc_parent >= MAXVIFS) {
+		rtm->rtm_flags |= RTNH_F_UNRESOLVED;
+		return -ENOENT;
+	}
+
+	if (VIF_EXISTS(mrt, c->mfc_parent) &&
+	    nla_put_u32(skb, RTA_IIF,
+			mrt->vif_table[c->mfc_parent].dev->ifindex) < 0)
+		return -EMSGSIZE;
+
+	if (c->mfc_flags & MFC_OFFLOAD)
+		rtm->rtm_flags |= RTNH_F_OFFLOAD;
+
+	mp_attr = nla_nest_start(skb, RTA_MULTIPATH);
+	if (!mp_attr)
+		return -EMSGSIZE;
+
+	for (ct = c->mfc_un.res.minvif; ct < c->mfc_un.res.maxvif; ct++) {
+		if (VIF_EXISTS(mrt, ct) && c->mfc_un.res.ttls[ct] < 255) {
+			struct vif_device *vif;
+
+			nhp = nla_reserve_nohdr(skb, sizeof(*nhp));
+			if (!nhp) {
+				nla_nest_cancel(skb, mp_attr);
+				return -EMSGSIZE;
+			}
+
+			nhp->rtnh_flags = 0;
+			nhp->rtnh_hops = c->mfc_un.res.ttls[ct];
+			vif = &mrt->vif_table[ct];
+			nhp->rtnh_ifindex = vif->dev->ifindex;
+			nhp->rtnh_len = sizeof(*nhp);
+		}
+	}
+
+	nla_nest_end(skb, mp_attr);
+
+	lastuse = READ_ONCE(c->mfc_un.res.lastuse);
+	lastuse = time_after_eq(jiffies, lastuse) ? jiffies - lastuse : 0;
+
+	mfcs.mfcs_packets = c->mfc_un.res.pkt;
+	mfcs.mfcs_bytes = c->mfc_un.res.bytes;
+	mfcs.mfcs_wrong_if = c->mfc_un.res.wrong_if;
+	if (nla_put_64bit(skb, RTA_MFC_STATS, sizeof(mfcs), &mfcs, RTA_PAD) ||
+	    nla_put_u64_64bit(skb, RTA_EXPIRES, jiffies_to_clock_t(lastuse),
+			      RTA_PAD))
+		return -EMSGSIZE;
+
+	rtm->rtm_type = RTN_MULTICAST;
+	return 1;
+}
+EXPORT_SYMBOL(mr_fill_mroute);
+
+int mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb,
+		     struct mr_table *(*iter)(struct net *net,
+					      struct mr_table *mrt),
+		     int (*fill)(struct mr_table *mrt,
+				 struct sk_buff *skb,
+				 u32 portid, u32 seq, struct mr_mfc *c,
+				 int cmd, int flags),
+		     spinlock_t *lock)
+{
+	unsigned int t = 0, e = 0, s_t = cb->args[0], s_e = cb->args[1];
+	struct net *net = sock_net(skb->sk);
+	struct mr_table *mrt;
+	struct mr_mfc *mfc;
+
+	rcu_read_lock();
+	for (mrt = iter(net, NULL); mrt; mrt = iter(net, mrt)) {
+		if (t < s_t)
+			goto next_table;
+		list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list) {
+			if (e < s_e)
+				goto next_entry;
+			if (fill(mrt, skb, NETLINK_CB(cb->skb).portid,
+				 cb->nlh->nlmsg_seq, mfc,
+				 RTM_NEWROUTE, NLM_F_MULTI) < 0)
+				goto done;
+next_entry:
+			e++;
+		}
+
+		spin_lock_bh(lock);
+		list_for_each_entry(mfc, &mrt->mfc_unres_queue, list) {
+			if (e < s_e)
+				goto next_entry2;
+			if (fill(mrt, skb, NETLINK_CB(cb->skb).portid,
+				 cb->nlh->nlmsg_seq, mfc,
+				 RTM_NEWROUTE, NLM_F_MULTI) < 0) {
+				spin_unlock_bh(lock);
+				goto done;
+			}
+next_entry2:
+			e++;
+		}
+		spin_unlock_bh(lock);
+		e = 0;
+		s_e = 0;
+next_table:
+		t++;
+	}
+done:
+	rcu_read_unlock();
+
+	cb->args[1] = e;
+	cb->args[0] = t;
+
+	return skb->len;
+}
+EXPORT_SYMBOL(mr_rtm_dumproute);
+
+int mr_dump(struct net *net, struct notifier_block *nb, unsigned short family,
+	    int (*rules_dump)(struct net *net,
+			      struct notifier_block *nb),
+	    struct mr_table *(*mr_iter)(struct net *net,
+					struct mr_table *mrt),
+	    rwlock_t *mrt_lock)
+{
+	struct mr_table *mrt;
+	int err;
+
+	err = rules_dump(net, nb);
+	if (err)
+		return err;
+
+	for (mrt = mr_iter(net, NULL); mrt; mrt = mr_iter(net, mrt)) {
+		struct vif_device *v = &mrt->vif_table[0];
+		struct mr_mfc *mfc;
+		int vifi;
+
+		/* Notifiy on table VIF entries */
+		read_lock(mrt_lock);
+		for (vifi = 0; vifi < mrt->maxvif; vifi++, v++) {
+			if (!v->dev)
+				continue;
+
+			mr_call_vif_notifier(nb, net, family,
+					     FIB_EVENT_VIF_ADD,
+					     v, vifi, mrt->id);
+		}
+		read_unlock(mrt_lock);
+
+		/* Notify on table MFC entries */
+		list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list)
+			mr_call_mfc_notifier(nb, net, family,
+					     FIB_EVENT_ENTRY_ADD,
+					     mfc, mrt->id);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(mr_dump);