1 files changed, 1480 insertions, 58 deletions

diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 743777bce179..4075230b14c6 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -16,6 +16,9 @@
 #include <net/route.h>
 #include <net/sock.h>
 
+#define NH_RES_DEFAULT_IDLE_TIMER	(120 * HZ)
+#define NH_RES_DEFAULT_UNBALANCED_TIMER	0	/* No forced rebalancing. */
+
 static void remove_nexthop(struct net *net, struct nexthop *nh,
 			   struct nl_info *nlinfo);
 
@@ -32,6 +35,7 @@ static const struct nla_policy rtm_nh_policy_new[] = {
 	[NHA_ENCAP_TYPE]	= { .type = NLA_U16 },
 	[NHA_ENCAP]		= { .type = NLA_NESTED },
 	[NHA_FDB]		= { .type = NLA_FLAG },
+	[NHA_RES_GROUP]		= { .type = NLA_NESTED },
 };
 
 static const struct nla_policy rtm_nh_policy_get[] = {
@@ -45,6 +49,32 @@ static const struct nla_policy rtm_nh_policy_dump[] = {
 	[NHA_FDB]		= { .type = NLA_FLAG },
 };
 
+static const struct nla_policy rtm_nh_res_policy_new[] = {
+	[NHA_RES_GROUP_BUCKETS]			= { .type = NLA_U16 },
+	[NHA_RES_GROUP_IDLE_TIMER]		= { .type = NLA_U32 },
+	[NHA_RES_GROUP_UNBALANCED_TIMER]	= { .type = NLA_U32 },
+};
+
+static const struct nla_policy rtm_nh_policy_dump_bucket[] = {
+	[NHA_ID]		= { .type = NLA_U32 },
+	[NHA_OIF]		= { .type = NLA_U32 },
+	[NHA_MASTER]		= { .type = NLA_U32 },
+	[NHA_RES_BUCKET]	= { .type = NLA_NESTED },
+};
+
+static const struct nla_policy rtm_nh_res_bucket_policy_dump[] = {
+	[NHA_RES_BUCKET_NH_ID]	= { .type = NLA_U32 },
+};
+
+static const struct nla_policy rtm_nh_policy_get_bucket[] = {
+	[NHA_ID]		= { .type = NLA_U32 },
+	[NHA_RES_BUCKET]	= { .type = NLA_NESTED },
+};
+
+static const struct nla_policy rtm_nh_res_bucket_policy_get[] = {
+	[NHA_RES_BUCKET_INDEX]	= { .type = NLA_U16 },
+};
+
 static bool nexthop_notifiers_is_empty(struct net *net)
 {
 	return !net->nexthop.notifier_chain.head;
@@ -52,10 +82,8 @@ static bool nexthop_notifiers_is_empty(struct net *net)
 
 static void
 __nh_notifier_single_info_init(struct nh_notifier_single_info *nh_info,
-			       const struct nexthop *nh)
+			       const struct nh_info *nhi)
 {
-	struct nh_info *nhi = rtnl_dereference(nh->nh_info);
-
 	nh_info->dev = nhi->fib_nhc.nhc_dev;
 	nh_info->gw_family = nhi->fib_nhc.nhc_gw_family;
 	if (nh_info->gw_family == AF_INET)
@@ -71,12 +99,14 @@ __nh_notifier_single_info_init(struct nh_notifier_single_info *nh_info,
 static int nh_notifier_single_info_init(struct nh_notifier_info *info,
 					const struct nexthop *nh)
 {
+	struct nh_info *nhi = rtnl_dereference(nh->nh_info);
+
 	info->type = NH_NOTIFIER_INFO_TYPE_SINGLE;
 	info->nh = kzalloc(sizeof(*info->nh), GFP_KERNEL);
 	if (!info->nh)
 		return -ENOMEM;
 
-	__nh_notifier_single_info_init(info->nh, nh);
+	__nh_notifier_single_info_init(info->nh, nhi);
 
 	return 0;
 }
@@ -86,8 +116,8 @@ static void nh_notifier_single_info_fini(struct nh_notifier_info *info)
 	kfree(info->nh);
 }
 
-static int nh_notifier_mp_info_init(struct nh_notifier_info *info,
-				    struct nh_group *nhg)
+static int nh_notifier_mpath_info_init(struct nh_notifier_info *info,
+				       struct nh_group *nhg)
 {
 	u16 num_nh = nhg->num_nh;
 	int i;
@@ -103,11 +133,44 @@ static int nh_notifier_mp_info_init(struct nh_notifier_info *info,
 
 	for (i = 0; i < num_nh; i++) {
 		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
+		struct nh_info *nhi;
 
+		nhi = rtnl_dereference(nhge->nh->nh_info);
 		info->nh_grp->nh_entries[i].id = nhge->nh->id;
 		info->nh_grp->nh_entries[i].weight = nhge->weight;
 		__nh_notifier_single_info_init(&info->nh_grp->nh_entries[i].nh,
-					       nhge->nh);
+					       nhi);
+	}
+
+	return 0;
+}
+
+static int nh_notifier_res_table_info_init(struct nh_notifier_info *info,
+					   struct nh_group *nhg)
+{
+	struct nh_res_table *res_table = rtnl_dereference(nhg->res_table);
+	u16 num_nh_buckets = res_table->num_nh_buckets;
+	unsigned long size;
+	u16 i;
+
+	info->type = NH_NOTIFIER_INFO_TYPE_RES_TABLE;
+	size = struct_size(info->nh_res_table, nhs, num_nh_buckets);
+	info->nh_res_table = __vmalloc(size, GFP_KERNEL | __GFP_ZERO |
+				       __GFP_NOWARN);
+	if (!info->nh_res_table)
+		return -ENOMEM;
+
+	info->nh_res_table->num_nh_buckets = num_nh_buckets;
+
+	for (i = 0; i < num_nh_buckets; i++) {
+		struct nh_res_bucket *bucket = &res_table->nh_buckets[i];
+		struct nh_grp_entry *nhge;
+		struct nh_info *nhi;
+
+		nhge = rtnl_dereference(bucket->nh_entry);
+		nhi = rtnl_dereference(nhge->nh->nh_info);
+		__nh_notifier_single_info_init(&info->nh_res_table->nhs[i],
+					       nhi);
 	}
 
 	return 0;
@@ -118,8 +181,10 @@ static int nh_notifier_grp_info_init(struct nh_notifier_info *info,
 {
 	struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 
-	if (nhg->mpath)
-		return nh_notifier_mp_info_init(info, nhg);
+	if (nhg->hash_threshold)
+		return nh_notifier_mpath_info_init(info, nhg);
+	else if (nhg->resilient)
+		return nh_notifier_res_table_info_init(info, nhg);
 	return -EINVAL;
 }
 
@@ -128,8 +193,10 @@ static void nh_notifier_grp_info_fini(struct nh_notifier_info *info,
 {
 	struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 
-	if (nhg->mpath)
+	if (nhg->hash_threshold)
 		kfree(info->nh_grp);
+	else if (nhg->resilient)
+		vfree(info->nh_res_table);
 }
 
 static int nh_notifier_info_init(struct nh_notifier_info *info,
@@ -181,6 +248,178 @@ static int call_nexthop_notifiers(struct net *net,
 	return notifier_to_errno(err);
 }
 
+static int
+nh_notifier_res_bucket_idle_timer_get(const struct nh_notifier_info *info,
+				      bool force, unsigned int *p_idle_timer_ms)
+{
+	struct nh_res_table *res_table;
+	struct nh_group *nhg;
+	struct nexthop *nh;
+	int err = 0;
+
+	/* When 'force' is false, nexthop bucket replacement is performed
+	 * because the bucket was deemed to be idle. In this case, capable
+	 * listeners can choose to perform an atomic replacement: The bucket is
+	 * only replaced if it is inactive. However, if the idle timer interval
+	 * is smaller than the interval in which a listener is querying
+	 * buckets' activity from the device, then atomic replacement should
+	 * not be tried. Pass the idle timer value to listeners, so that they
+	 * could determine which type of replacement to perform.
+	 */
+	if (force) {
+		*p_idle_timer_ms = 0;
+		return 0;
+	}
+
+	rcu_read_lock();
+
+	nh = nexthop_find_by_id(info->net, info->id);
+	if (!nh) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	nhg = rcu_dereference(nh->nh_grp);
+	res_table = rcu_dereference(nhg->res_table);
+	*p_idle_timer_ms = jiffies_to_msecs(res_table->idle_timer);
+
+out:
+	rcu_read_unlock();
+
+	return err;
+}
+
+static int nh_notifier_res_bucket_info_init(struct nh_notifier_info *info,
+					    u16 bucket_index, bool force,
+					    struct nh_info *oldi,
+					    struct nh_info *newi)
+{
+	unsigned int idle_timer_ms;
+	int err;
+
+	err = nh_notifier_res_bucket_idle_timer_get(info, force,
+						    &idle_timer_ms);
+	if (err)
+		return err;
+
+	info->type = NH_NOTIFIER_INFO_TYPE_RES_BUCKET;
+	info->nh_res_bucket = kzalloc(sizeof(*info->nh_res_bucket),
+				      GFP_KERNEL);
+	if (!info->nh_res_bucket)
+		return -ENOMEM;
+
+	info->nh_res_bucket->bucket_index = bucket_index;
+	info->nh_res_bucket->idle_timer_ms = idle_timer_ms;
+	info->nh_res_bucket->force = force;
+	__nh_notifier_single_info_init(&info->nh_res_bucket->old_nh, oldi);
+	__nh_notifier_single_info_init(&info->nh_res_bucket->new_nh, newi);
+	return 0;
+}
+
+static void nh_notifier_res_bucket_info_fini(struct nh_notifier_info *info)
+{
+	kfree(info->nh_res_bucket);
+}
+
+static int __call_nexthop_res_bucket_notifiers(struct net *net, u32 nhg_id,
+					       u16 bucket_index, bool force,
+					       struct nh_info *oldi,
+					       struct nh_info *newi,
+					       struct netlink_ext_ack *extack)
+{
+	struct nh_notifier_info info = {
+		.net = net,
+		.extack = extack,
+		.id = nhg_id,
+	};
+	int err;
+
+	if (nexthop_notifiers_is_empty(net))
+		return 0;
+
+	err = nh_notifier_res_bucket_info_init(&info, bucket_index, force,
+					       oldi, newi);
+	if (err)
+		return err;
+
+	err = blocking_notifier_call_chain(&net->nexthop.notifier_chain,
+					   NEXTHOP_EVENT_BUCKET_REPLACE, &info);
+	nh_notifier_res_bucket_info_fini(&info);
+
+	return notifier_to_errno(err);
+}
+
+/* There are three users of RES_TABLE, and NHs etc. referenced from there:
+ *
+ * 1) a collection of callbacks for NH maintenance. This operates under
+ *    RTNL,
+ * 2) the delayed work that gradually balances the resilient table,
+ * 3) and nexthop_select_path(), operating under RCU.
+ *
+ * Both the delayed work and the RTNL block are writers, and need to
+ * maintain mutual exclusion. Since there are only two and well-known
+ * writers for each table, the RTNL code can make sure it has exclusive
+ * access thus:
+ *
+ * - Have the DW operate without locking;
+ * - synchronously cancel the DW;
+ * - do the writing;
+ * - if the write was not actually a delete, call upkeep, which schedules
+ *   DW again if necessary.
+ *
+ * The functions that are always called from the RTNL context use
+ * rtnl_dereference(). The functions that can also be called from the DW do
+ * a raw dereference and rely on the above mutual exclusion scheme.
+ */
+#define nh_res_dereference(p) (rcu_dereference_raw(p))
+
+static int call_nexthop_res_bucket_notifiers(struct net *net, u32 nhg_id,
+					     u16 bucket_index, bool force,
+					     struct nexthop *old_nh,
+					     struct nexthop *new_nh,
+					     struct netlink_ext_ack *extack)
+{
+	struct nh_info *oldi = nh_res_dereference(old_nh->nh_info);
+	struct nh_info *newi = nh_res_dereference(new_nh->nh_info);
+
+	return __call_nexthop_res_bucket_notifiers(net, nhg_id, bucket_index,
+						   force, oldi, newi, extack);
+}
+
+static int call_nexthop_res_table_notifiers(struct net *net, struct nexthop *nh,
+					    struct netlink_ext_ack *extack)
+{
+	struct nh_notifier_info info = {
+		.net = net,
+		.extack = extack,
+	};
+	struct nh_group *nhg;
+	int err;
+
+	ASSERT_RTNL();
+
+	if (nexthop_notifiers_is_empty(net))
+		return 0;
+
+	/* At this point, the nexthop buckets are still not populated. Only
+	 * emit a notification with the logical nexthops, so that a listener
+	 * could potentially veto it in case of unsupported configuration.
+	 */
+	nhg = rtnl_dereference(nh->nh_grp);
+	err = nh_notifier_mpath_info_init(&info, nhg);
+	if (err) {
+		NL_SET_ERR_MSG(extack, "Failed to initialize nexthop notifier info");
+		return err;
+	}
+
+	err = blocking_notifier_call_chain(&net->nexthop.notifier_chain,
+					   NEXTHOP_EVENT_RES_TABLE_PRE_REPLACE,
+					   &info);
+	kfree(info.nh_grp);
+
+	return notifier_to_errno(err);
+}
+
 static int call_nexthop_notifier(struct notifier_block *nb, struct net *net,
 				 enum nexthop_event_type event_type,
 				 struct nexthop *nh,
@@ -239,6 +478,9 @@ static void nexthop_free_group(struct nexthop *nh)
 
 	WARN_ON(nhg->spare == nhg);
 
+	if (nhg->resilient)
+		vfree(rcu_dereference_raw(nhg->res_table));
+
 	kfree(nhg->spare);
 	kfree(nhg);
 }
@@ -297,6 +539,30 @@ static struct nh_group *nexthop_grp_alloc(u16 num_nh)
 	return nhg;
 }
 
+static void nh_res_table_upkeep_dw(struct work_struct *work);
+
+static struct nh_res_table *
+nexthop_res_table_alloc(struct net *net, u32 nhg_id, struct nh_config *cfg)
+{
+	const u16 num_nh_buckets = cfg->nh_grp_res_num_buckets;
+	struct nh_res_table *res_table;
+	unsigned long size;
+
+	size = struct_size(res_table, nh_buckets, num_nh_buckets);
+	res_table = __vmalloc(size, GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN);
+	if (!res_table)
+		return NULL;
+
+	res_table->net = net;
+	res_table->nhg_id = nhg_id;
+	INIT_DELAYED_WORK(&res_table->upkeep_dw, &nh_res_table_upkeep_dw);
+	INIT_LIST_HEAD(&res_table->uw_nh_entries);
+	res_table->idle_timer = cfg->nh_grp_res_idle_timer;
+	res_table->unbalanced_timer = cfg->nh_grp_res_unbalanced_timer;
+	res_table->num_nh_buckets = num_nh_buckets;
+	return res_table;
+}
+
 static void nh_base_seq_inc(struct net *net)
 {
 	while (++net->nexthop.seq == 0)
@@ -345,6 +611,48 @@ static u32 nh_find_unused_id(struct net *net)
 	return 0;
 }
 
+static void nh_res_time_set_deadline(unsigned long next_time,
+				     unsigned long *deadline)
+{
+	if (time_before(next_time, *deadline))
+		*deadline = next_time;
+}
+
+static clock_t nh_res_table_unbalanced_time(struct nh_res_table *res_table)
+{
+	if (list_empty(&res_table->uw_nh_entries))
+		return 0;
+	return jiffies_delta_to_clock_t(jiffies - res_table->unbalanced_since);
+}
+
+static int nla_put_nh_group_res(struct sk_buff *skb, struct nh_group *nhg)
+{
+	struct nh_res_table *res_table = rtnl_dereference(nhg->res_table);
+	struct nlattr *nest;
+
+	nest = nla_nest_start(skb, NHA_RES_GROUP);
+	if (!nest)
+		return -EMSGSIZE;
+
+	if (nla_put_u16(skb, NHA_RES_GROUP_BUCKETS,
+			res_table->num_nh_buckets) ||
+	    nla_put_u32(skb, NHA_RES_GROUP_IDLE_TIMER,
+			jiffies_to_clock_t(res_table->idle_timer)) ||
+	    nla_put_u32(skb, NHA_RES_GROUP_UNBALANCED_TIMER,
+			jiffies_to_clock_t(res_table->unbalanced_timer)) ||
+	    nla_put_u64_64bit(skb, NHA_RES_GROUP_UNBALANCED_TIME,
+			      nh_res_table_unbalanced_time(res_table),
+			      NHA_RES_GROUP_PAD))
+		goto nla_put_failure;
+
+	nla_nest_end(skb, nest);
+	return 0;
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -EMSGSIZE;
+}
+
 static int nla_put_nh_group(struct sk_buff *skb, struct nh_group *nhg)
 {
 	struct nexthop_grp *p;
@@ -353,8 +661,10 @@ static int nla_put_nh_group(struct sk_buff *skb, struct nh_group *nhg)
 	u16 group_type = 0;
 	int i;
 
-	if (nhg->mpath)
+	if (nhg->hash_threshold)
 		group_type = NEXTHOP_GRP_TYPE_MPATH;
+	else if (nhg->resilient)
+		group_type = NEXTHOP_GRP_TYPE_RES;
 
 	if (nla_put_u16(skb, NHA_GROUP_TYPE, group_type))
 		goto nla_put_failure;
@@ -370,6 +680,9 @@ static int nla_put_nh_group(struct sk_buff *skb, struct nh_group *nhg)
 		p += 1;
 	}
 
+	if (nhg->resilient && nla_put_nh_group_res(skb, nhg))
+		goto nla_put_failure;
+
 	return 0;
 
 nla_put_failure:
@@ -457,13 +770,26 @@ nla_put_failure:
 	return -EMSGSIZE;
 }
 
+static size_t nh_nlmsg_size_grp_res(struct nh_group *nhg)
+{
+	return nla_total_size(0) +	/* NHA_RES_GROUP */
+		nla_total_size(2) +	/* NHA_RES_GROUP_BUCKETS */
+		nla_total_size(4) +	/* NHA_RES_GROUP_IDLE_TIMER */
+		nla_total_size(4) +	/* NHA_RES_GROUP_UNBALANCED_TIMER */
+		nla_total_size_64bit(8);/* NHA_RES_GROUP_UNBALANCED_TIME */
+}
+
 static size_t nh_nlmsg_size_grp(struct nexthop *nh)
 {
 	struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 	size_t sz = sizeof(struct nexthop_grp) * nhg->num_nh;
+	size_t tot = nla_total_size(sz) +
+		nla_total_size(2); /* NHA_GROUP_TYPE */
 
-	return nla_total_size(sz) +
-	       nla_total_size(2);  /* NHA_GROUP_TYPE */
+	if (nhg->resilient)
+		tot += nh_nlmsg_size_grp_res(nhg);
+
+	return tot;
 }
 
 static size_t nh_nlmsg_size_single(struct nexthop *nh)
@@ -538,18 +864,142 @@ errout:
 		rtnl_set_sk_err(info->nl_net, RTNLGRP_NEXTHOP, err);
 }
 
+static unsigned long nh_res_bucket_used_time(const struct nh_res_bucket *bucket)
+{
+	return (unsigned long)atomic_long_read(&bucket->used_time);
+}
+
+static unsigned long
+nh_res_bucket_idle_point(const struct nh_res_table *res_table,
+			 const struct nh_res_bucket *bucket,
+			 unsigned long now)
+{
+	unsigned long time = nh_res_bucket_used_time(bucket);
+
+	/* Bucket was not used since it was migrated. The idle time is now. */
+	if (time == bucket->migrated_time)
+		return now;
+
+	return time + res_table->idle_timer;
+}
+
+static unsigned long
+nh_res_table_unb_point(const struct nh_res_table *res_table)
+{
+	return res_table->unbalanced_since + res_table->unbalanced_timer;
+}
+
+static void nh_res_bucket_set_idle(const struct nh_res_table *res_table,
+				   struct nh_res_bucket *bucket)
+{
+	unsigned long now = jiffies;
+
+	atomic_long_set(&bucket->used_time, (long)now);
+	bucket->migrated_time = now;
+}
+
+static void nh_res_bucket_set_busy(struct nh_res_bucket *bucket)
+{
+	atomic_long_set(&bucket->used_time, (long)jiffies);
+}
+
+static clock_t nh_res_bucket_idle_time(const struct nh_res_bucket *bucket)
+{
+	unsigned long used_time = nh_res_bucket_used_time(bucket);
+
+	return jiffies_delta_to_clock_t(jiffies - used_time);
+}
+
+static int nh_fill_res_bucket(struct sk_buff *skb, struct nexthop *nh,
+			      struct nh_res_bucket *bucket, u16 bucket_index,
+			      int event, u32 portid, u32 seq,
+			      unsigned int nlflags,
+			      struct netlink_ext_ack *extack)
+{
+	struct nh_grp_entry *nhge = nh_res_dereference(bucket->nh_entry);
+	struct nlmsghdr *nlh;
+	struct nlattr *nest;
+	struct nhmsg *nhm;
+
+	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nhm), nlflags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	nhm = nlmsg_data(nlh);
+	nhm->nh_family = AF_UNSPEC;
+	nhm->nh_flags = bucket->nh_flags;
+	nhm->nh_protocol = nh->protocol;
+	nhm->nh_scope = 0;
+	nhm->resvd = 0;
+
+	if (nla_put_u32(skb, NHA_ID, nh->id))
+		goto nla_put_failure;
+
+	nest = nla_nest_start(skb, NHA_RES_BUCKET);
+	if (!nest)
+		goto nla_put_failure;
+
+	if (nla_put_u16(skb, NHA_RES_BUCKET_INDEX, bucket_index) ||
+	    nla_put_u32(skb, NHA_RES_BUCKET_NH_ID, nhge->nh->id) ||
+	    nla_put_u64_64bit(skb, NHA_RES_BUCKET_IDLE_TIME,
+			      nh_res_bucket_idle_time(bucket),
+			      NHA_RES_BUCKET_PAD))
+		goto nla_put_failure_nest;
+
+	nla_nest_end(skb, nest);
+	nlmsg_end(skb, nlh);
+	return 0;
+
+nla_put_failure_nest:
+	nla_nest_cancel(skb, nest);
+nla_put_failure:
+	nlmsg_cancel(skb, nlh);
+	return -EMSGSIZE;
+}
+
+static void nexthop_bucket_notify(struct nh_res_table *res_table,
+				  u16 bucket_index)
+{
+	struct nh_res_bucket *bucket = &res_table->nh_buckets[bucket_index];
+	struct nh_grp_entry *nhge = nh_res_dereference(bucket->nh_entry);
+	struct nexthop *nh = nhge->nh_parent;
+	struct sk_buff *skb;
+	int err = -ENOBUFS;
+
+	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!skb)
+		goto errout;
+
+	err = nh_fill_res_bucket(skb, nh, bucket, bucket_index,
+				 RTM_NEWNEXTHOPBUCKET, 0, 0, NLM_F_REPLACE,
+				 NULL);
+	if (err < 0) {
+		kfree_skb(skb);
+		goto errout;
+	}
+
+	rtnl_notify(skb, nh->net, 0, RTNLGRP_NEXTHOP, NULL, GFP_KERNEL);
+	return;
+errout:
+	if (err < 0)
+		rtnl_set_sk_err(nh->net, RTNLGRP_NEXTHOP, err);
+}
+
 static bool valid_group_nh(struct nexthop *nh, unsigned int npaths,
 			   bool *is_fdb, struct netlink_ext_ack *extack)
 {
 	if (nh->is_group) {
 		struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 
-		/* nested multipath (group within a group) is not
-		 * supported
-		 */
-		if (nhg->mpath) {
+		/* Nesting groups within groups is not supported. */
+		if (nhg->hash_threshold) {
 			NL_SET_ERR_MSG(extack,
-				       "Multipath group can not be a nexthop within a group");
+				       "Hash-threshold group can not be a nexthop within a group");
+			return false;
+		}
+		if (nhg->resilient) {
+			NL_SET_ERR_MSG(extack,
+				       "Resilient group can not be a nexthop within a group");
 			return false;
 		}
 		*is_fdb = nhg->fdb_nh;
@@ -591,7 +1041,7 @@ static int nh_check_attr_fdb_group(struct nexthop *nh, u8 *nh_family,
 
 static int nh_check_attr_group(struct net *net,
 			       struct nlattr *tb[], size_t tb_size,
-			       struct netlink_ext_ack *extack)
+			       u16 nh_grp_type, struct netlink_ext_ack *extack)
 {
 	unsigned int len = nla_len(tb[NHA_GROUP]);
 	u8 nh_family = AF_UNSPEC;
@@ -652,8 +1102,14 @@ static int nh_check_attr_group(struct net *net,
 	for (i = NHA_GROUP_TYPE + 1; i < tb_size; ++i) {
 		if (!tb[i])
 			continue;
-		if (i == NHA_FDB)
+		switch (i) {
+		case NHA_FDB:
 			continue;
+		case NHA_RES_GROUP:
+			if (nh_grp_type == NEXTHOP_GRP_TYPE_RES)
+				continue;
+			break;
+		}
 		NL_SET_ERR_MSG(extack,
 			       "No other attributes can be set in nexthop groups");
 		return -EINVAL;
@@ -695,7 +1151,7 @@ static bool ipv4_good_nh(const struct fib_nh *nh)
 	return !!(state & NUD_VALID);
 }
 
-static struct nexthop *nexthop_select_path_mp(struct nh_group *nhg, int hash)
+static struct nexthop *nexthop_select_path_hthr(struct nh_group *nhg, int hash)
 {
 	struct nexthop *rc = NULL;
 	int i;
@@ -704,7 +1160,7 @@ static struct nexthop *nexthop_select_path_mp(struct nh_group *nhg, int hash)
 		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
 		struct nh_info *nhi;
 
-		if (hash > atomic_read(&nhge->mpath.upper_bound))
+		if (hash > atomic_read(&nhge->hthr.upper_bound))
 			continue;
 
 		nhi = rcu_dereference(nhge->nh->nh_info);
@@ -732,6 +1188,22 @@ static struct nexthop *nexthop_select_path_mp(struct nh_group *nhg, int hash)
 	return rc;
 }
 
+static struct nexthop *nexthop_select_path_res(struct nh_group *nhg, int hash)
+{
+	struct nh_res_table *res_table = rcu_dereference(nhg->res_table);
+	u16 bucket_index = hash % res_table->num_nh_buckets;
+	struct nh_res_bucket *bucket;
+	struct nh_grp_entry *nhge;
+
+	/* nexthop_select_path() is expected to return a non-NULL value, so
+	 * skip protocol validation and just hand out whatever there is.
+	 */
+	bucket = &res_table->nh_buckets[bucket_index];
+	nh_res_bucket_set_busy(bucket);
+	nhge = rcu_dereference(bucket->nh_entry);
+	return nhge->nh;
+}
+
 struct nexthop *nexthop_select_path(struct nexthop *nh, int hash)
 {
 	struct nh_group *nhg;
@@ -740,8 +1212,10 @@ struct nexthop *nexthop_select_path(struct nexthop *nh, int hash)
 		return nh;
 
 	nhg = rcu_dereference(nh->nh_grp);
-	if (nhg->mpath)
-		return nexthop_select_path_mp(nhg, hash);
+	if (nhg->hash_threshold)
+		return nexthop_select_path_hthr(nhg, hash);
+	else if (nhg->resilient)
+		return nexthop_select_path_res(nhg, hash);
 
 	/* Unreachable. */
 	return NULL;
@@ -924,7 +1398,319 @@ static int fib_check_nh_list(struct nexthop *old, struct nexthop *new,
 	return 0;
 }
 
-static void nh_group_rebalance(struct nh_group *nhg)
+static bool nh_res_nhge_is_balanced(const struct nh_grp_entry *nhge)
+{
+	return nhge->res.count_buckets == nhge->res.wants_buckets;
+}
+
+static bool nh_res_nhge_is_ow(const struct nh_grp_entry *nhge)
+{
+	return nhge->res.count_buckets > nhge->res.wants_buckets;
+}
+
+static bool nh_res_nhge_is_uw(const struct nh_grp_entry *nhge)
+{
+	return nhge->res.count_buckets < nhge->res.wants_buckets;
+}
+
+static bool nh_res_table_is_balanced(const struct nh_res_table *res_table)
+{
+	return list_empty(&res_table->uw_nh_entries);
+}
+
+static void nh_res_bucket_unset_nh(struct nh_res_bucket *bucket)
+{
+	struct nh_grp_entry *nhge;
+
+	if (bucket->occupied) {
+		nhge = nh_res_dereference(bucket->nh_entry);
+		nhge->res.count_buckets--;
+		bucket->occupied = false;
+	}
+}
+
+static void nh_res_bucket_set_nh(struct nh_res_bucket *bucket,
+				 struct nh_grp_entry *nhge)
+{
+	nh_res_bucket_unset_nh(bucket);
+
+	bucket->occupied = true;
+	rcu_assign_pointer(bucket->nh_entry, nhge);
+	nhge->res.count_buckets++;
+}
+
+static bool nh_res_bucket_should_migrate(struct nh_res_table *res_table,
+					 struct nh_res_bucket *bucket,
+					 unsigned long *deadline, bool *force)
+{
+	unsigned long now = jiffies;
+	struct nh_grp_entry *nhge;
+	unsigned long idle_point;
+
+	if (!bucket->occupied) {
+		/* The bucket is not occupied, its NHGE pointer is either
+		 * NULL or obsolete. We _have to_ migrate: set force.
+		 */
+		*force = true;
+		return true;
+	}
+
+	nhge = nh_res_dereference(bucket->nh_entry);
+
+	/* If the bucket is populated by an underweight or balanced
+	 * nexthop, do not migrate.
+	 */
+	if (!nh_res_nhge_is_ow(nhge))
+		return false;
+
+	/* At this point we know that the bucket is populated with an
+	 * overweight nexthop. It needs to be migrated to a new nexthop if
+	 * the idle timer of unbalanced timer expired.
+	 */
+
+	idle_point = nh_res_bucket_idle_point(res_table, bucket, now);
+	if (time_after_eq(now, idle_point)) {
+		/* The bucket is idle. We _can_ migrate: unset force. */
+		*force = false;
+		return true;
+	}
+
+	/* Unbalanced timer of 0 means "never force". */
+	if (res_table->unbalanced_timer) {
+		unsigned long unb_point;
+
+		unb_point = nh_res_table_unb_point(res_table);
+		if (time_after(now, unb_point)) {
+			/* The bucket is not idle, but the unbalanced timer
+			 * expired. We _can_ migrate, but set force anyway,
+			 * so that drivers know to ignore activity reports
+			 * from the HW.
+			 */
+			*force = true;
+			return true;
+		}
+
+		nh_res_time_set_deadline(unb_point, deadline);
+	}
+
+	nh_res_time_set_deadline(idle_point, deadline);
+	return false;
+}
+
+static bool nh_res_bucket_migrate(struct nh_res_table *res_table,
+				  u16 bucket_index, bool notify,
+				  bool notify_nl, bool force)
+{
+	struct nh_res_bucket *bucket = &res_table->nh_buckets[bucket_index];
+	struct nh_grp_entry *new_nhge;
+	struct netlink_ext_ack extack;
+	int err;
+
+	new_nhge = list_first_entry_or_null(&res_table->uw_nh_entries,
+					    struct nh_grp_entry,
+					    res.uw_nh_entry);
+	if (WARN_ON_ONCE(!new_nhge))
+		/* If this function is called, "bucket" is either not
+		 * occupied, or it belongs to a next hop that is
+		 * overweight. In either case, there ought to be a
+		 * corresponding underweight next hop.
+		 */
+		return false;
+
+	if (notify) {
+		struct nh_grp_entry *old_nhge;
+
+		old_nhge = nh_res_dereference(bucket->nh_entry);
+		err = call_nexthop_res_bucket_notifiers(res_table->net,
+							res_table->nhg_id,
+							bucket_index, force,
+							old_nhge->nh,
+							new_nhge->nh, &extack);
+		if (err) {
+			pr_err_ratelimited("%s\n", extack._msg);
+			if (!force)
+				return false;
+			/* It is not possible to veto a forced replacement, so
+			 * just clear the hardware flags from the nexthop
+			 * bucket to indicate to user space that this bucket is
+			 * not correctly populated in hardware.
+			 */
+			bucket->nh_flags &= ~(RTNH_F_OFFLOAD | RTNH_F_TRAP);
+		}
+	}
+
+	nh_res_bucket_set_nh(bucket, new_nhge);
+	nh_res_bucket_set_idle(res_table, bucket);
+
+	if (notify_nl)
+		nexthop_bucket_notify(res_table, bucket_index);
+
+	if (nh_res_nhge_is_balanced(new_nhge))
+		list_del(&new_nhge->res.uw_nh_entry);
+	return true;
+}
+
+#define NH_RES_UPKEEP_DW_MINIMUM_INTERVAL (HZ / 2)
+
+static void nh_res_table_upkeep(struct nh_res_table *res_table,
+				bool notify, bool notify_nl)
+{
+	unsigned long now = jiffies;
+	unsigned long deadline;
+	u16 i;
+
+	/* Deadline is the next time that upkeep should be run. It is the
+	 * earliest time at which one of the buckets might be migrated.
+	 * Start at the most pessimistic estimate: either unbalanced_timer
+	 * from now, or if there is none, idle_timer from now. For each
+	 * encountered time point, call nh_res_time_set_deadline() to
+	 * refine the estimate.
+	 */
+	if (res_table->unbalanced_timer)
+		deadline = now + res_table->unbalanced_timer;
+	else
+		deadline = now + res_table->idle_timer;
+
+	for (i = 0; i < res_table->num_nh_buckets; i++) {
+		struct nh_res_bucket *bucket = &res_table->nh_buckets[i];
+		bool force;
+
+		if (nh_res_bucket_should_migrate(res_table, bucket,
+						 &deadline, &force)) {
+			if (!nh_res_bucket_migrate(res_table, i, notify,
+						   notify_nl, force)) {
+				unsigned long idle_point;
+
+				/* A driver can override the migration
+				 * decision if the HW reports that the
+				 * bucket is actually not idle. Therefore
+				 * remark the bucket as busy again and
+				 * update the deadline.
+				 */
+				nh_res_bucket_set_busy(bucket);
+				idle_point = nh_res_bucket_idle_point(res_table,
+								      bucket,
+								      now);
+				nh_res_time_set_deadline(idle_point, &deadline);
+			}
+		}
+	}
+
+	/* If the group is still unbalanced, schedule the next upkeep to
+	 * either the deadline computed above, or the minimum deadline,
+	 * whichever comes later.
+	 */
+	if (!nh_res_table_is_balanced(res_table)) {
+		unsigned long now = jiffies;
+		unsigned long min_deadline;
+
+		min_deadline = now + NH_RES_UPKEEP_DW_MINIMUM_INTERVAL;
+		if (time_before(deadline, min_deadline))
+			deadline = min_deadline;
+
+		queue_delayed_work(system_power_efficient_wq,
+				   &res_table->upkeep_dw, deadline - now);
+	}
+}
+
+static void nh_res_table_upkeep_dw(struct work_struct *work)
+{
+	struct delayed_work *dw = to_delayed_work(work);
+	struct nh_res_table *res_table;
+
+	res_table = container_of(dw, struct nh_res_table, upkeep_dw);
+	nh_res_table_upkeep(res_table, true, true);
+}
+
+static void nh_res_table_cancel_upkeep(struct nh_res_table *res_table)
+{
+	cancel_delayed_work_sync(&res_table->upkeep_dw);
+}
+
+static void nh_res_group_rebalance(struct nh_group *nhg,
+				   struct nh_res_table *res_table)
+{
+	int prev_upper_bound = 0;
+	int total = 0;
+	int w = 0;
+	int i;
+
+	INIT_LIST_HEAD(&res_table->uw_nh_entries);
+
+	for (i = 0; i < nhg->num_nh; ++i)
+		total += nhg->nh_entries[i].weight;
+
+	for (i = 0; i < nhg->num_nh; ++i) {
+		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
+		int upper_bound;
+
+		w += nhge->weight;
+		upper_bound = DIV_ROUND_CLOSEST(res_table->num_nh_buckets * w,
+						total);
+		nhge->res.wants_buckets = upper_bound - prev_upper_bound;
+		prev_upper_bound = upper_bound;
+
+		if (nh_res_nhge_is_uw(nhge)) {
+			if (list_empty(&res_table->uw_nh_entries))
+				res_table->unbalanced_since = jiffies;
+			list_add(&nhge->res.uw_nh_entry,
+				 &res_table->uw_nh_entries);
+		}
+	}
+}
+
+/* Migrate buckets in res_table so that they reference NHGE's from NHG with
+ * the right NH ID. Set those buckets that do not have a corresponding NHGE
+ * entry in NHG as not occupied.
+ */
+static void nh_res_table_migrate_buckets(struct nh_res_table *res_table,
+					 struct nh_group *nhg)
+{
+	u16 i;
+
+	for (i = 0; i < res_table->num_nh_buckets; i++) {
+		struct nh_res_bucket *bucket = &res_table->nh_buckets[i];
+		u32 id = rtnl_dereference(bucket->nh_entry)->nh->id;
+		bool found = false;
+		int j;
+
+		for (j = 0; j < nhg->num_nh; j++) {
+			struct nh_grp_entry *nhge = &nhg->nh_entries[j];
+
+			if (nhge->nh->id == id) {
+				nh_res_bucket_set_nh(bucket, nhge);
+				found = true;
+				break;
+			}
+		}
+
+		if (!found)
+			nh_res_bucket_unset_nh(bucket);
+	}
+}
+
+static void replace_nexthop_grp_res(struct nh_group *oldg,
+				    struct nh_group *newg)
+{
+	/* For NH group replacement, the new NHG might only have a stub
+	 * hash table with 0 buckets, because the number of buckets was not
+	 * specified. For NH removal, oldg and newg both reference the same
+	 * res_table. So in any case, in the following, we want to work
+	 * with oldg->res_table.
+	 */
+	struct nh_res_table *old_res_table = rtnl_dereference(oldg->res_table);
+	unsigned long prev_unbalanced_since = old_res_table->unbalanced_since;
+	bool prev_has_uw = !list_empty(&old_res_table->uw_nh_entries);
+
+	nh_res_table_cancel_upkeep(old_res_table);
+	nh_res_table_migrate_buckets(old_res_table, newg);
+	nh_res_group_rebalance(newg, old_res_table);
+	if (prev_has_uw && !list_empty(&old_res_table->uw_nh_entries))
+		old_res_table->unbalanced_since = prev_unbalanced_since;
+	nh_res_table_upkeep(old_res_table, true, false);
+}
+
+static void nh_hthr_group_rebalance(struct nh_group *nhg)
 {
 	int total = 0;
 	int w = 0;
@@ -939,7 +1725,7 @@ static void nh_group_rebalance(struct nh_group *nhg)
 
 		w += nhge->weight;
 		upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31, total) - 1;
-		atomic_set(&nhge->mpath.upper_bound, upper_bound);
+		atomic_set(&nhge->hthr.upper_bound, upper_bound);
 	}
 }
 
@@ -965,7 +1751,9 @@ static void remove_nh_grp_entry(struct net *net, struct nh_grp_entry *nhge,
 	}
 
 	newg->has_v4 = false;
-	newg->mpath = nhg->mpath;
+	newg->is_multipath = nhg->is_multipath;
+	newg->hash_threshold = nhg->hash_threshold;
+	newg->resilient = nhg->resilient;
 	newg->fdb_nh = nhg->fdb_nh;
 	newg->num_nh = nhg->num_nh;
 
@@ -993,15 +1781,25 @@ static void remove_nh_grp_entry(struct net *net, struct nh_grp_entry *nhge,
 		j++;
 	}
 
-	nh_group_rebalance(newg);
+	if (newg->hash_threshold)
+		nh_hthr_group_rebalance(newg);
+	else if (newg->resilient)
+		replace_nexthop_grp_res(nhg, newg);
+
 	rcu_assign_pointer(nhp->nh_grp, newg);
 
 	list_del(&nhge->nh_list);
 	nexthop_put(nhge->nh);
 
-	err = call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE, nhp, &extack);
-	if (err)
-		pr_err("%s\n", extack._msg);
+	/* Removal of a NH from a resilient group is notified through
+	 * bucket notifications.
+	 */
+	if (newg->hash_threshold) {
+		err = call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE, nhp,
+					     &extack);
+		if (err)
+			pr_err("%s\n", extack._msg);
+	}
 
 	if (nlinfo)
 		nexthop_notify(RTM_NEWNEXTHOP, nhp, nlinfo);
@@ -1022,6 +1820,7 @@ static void remove_nexthop_from_groups(struct net *net, struct nexthop *nh,
 static void remove_nexthop_group(struct nexthop *nh, struct nl_info *nlinfo)
 {
 	struct nh_group *nhg = rcu_dereference_rtnl(nh->nh_grp);
+	struct nh_res_table *res_table;
 	int i, num_nh = nhg->num_nh;
 
 	for (i = 0; i < num_nh; ++i) {
@@ -1032,6 +1831,11 @@ static void remove_nexthop_group(struct nexthop *nh, struct nl_info *nlinfo)
 
 		list_del_init(&nhge->nh_list);
 	}
+
+	if (nhg->resilient) {
+		res_table = rtnl_dereference(nhg->res_table);
+		nh_res_table_cancel_upkeep(res_table);
+	}
 }
 
 /* not called for nexthop replace */
@@ -1107,9 +1911,12 @@ static void nh_rt_cache_flush(struct net *net, struct nexthop *nh)
 }
 
 static int replace_nexthop_grp(struct net *net, struct nexthop *old,
-			       struct nexthop *new,
+			       struct nexthop *new, const struct nh_config *cfg,
 			       struct netlink_ext_ack *extack)
 {
+	struct nh_res_table *tmp_table = NULL;
+	struct nh_res_table *new_res_table;
+	struct nh_res_table *old_res_table;
 	struct nh_group *oldg, *newg;
 	int i, err;
 
@@ -1118,19 +1925,67 @@ static int replace_nexthop_grp(struct net *net, struct nexthop *old,
 		return -EINVAL;
 	}
 
-	err = call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE, new, extack);
-	if (err)
-		return err;
-
 	oldg = rtnl_dereference(old->nh_grp);
 	newg = rtnl_dereference(new->nh_grp);
 
+	if (newg->hash_threshold != oldg->hash_threshold) {
+		NL_SET_ERR_MSG(extack, "Can not replace a nexthop group with one of a different type.");
+		return -EINVAL;
+	}
+
+	if (newg->hash_threshold) {
+		err = call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE, new,
+					     extack);
+		if (err)
+			return err;
+	} else if (newg->resilient) {
+		new_res_table = rtnl_dereference(newg->res_table);
+		old_res_table = rtnl_dereference(oldg->res_table);
+
+		/* Accept if num_nh_buckets was not given, but if it was
+		 * given, demand that the value be correct.
+		 */
+		if (cfg->nh_grp_res_has_num_buckets &&
+		    cfg->nh_grp_res_num_buckets !=
+		    old_res_table->num_nh_buckets) {
+			NL_SET_ERR_MSG(extack, "Can not change number of buckets of a resilient nexthop group.");
+			return -EINVAL;
+		}
+
+		/* Emit a pre-replace notification so that listeners could veto
+		 * a potentially unsupported configuration. Otherwise,
+		 * individual bucket replacement notifications would need to be
+		 * vetoed, which is something that should only happen if the
+		 * bucket is currently active.
+		 */
+		err = call_nexthop_res_table_notifiers(net, new, extack);
+		if (err)
+			return err;
+
+		if (cfg->nh_grp_res_has_idle_timer)
+			old_res_table->idle_timer = cfg->nh_grp_res_idle_timer;
+		if (cfg->nh_grp_res_has_unbalanced_timer)
+			old_res_table->unbalanced_timer =
+				cfg->nh_grp_res_unbalanced_timer;
+
+		replace_nexthop_grp_res(oldg, newg);
+
+		tmp_table = new_res_table;
+		rcu_assign_pointer(newg->res_table, old_res_table);
+		rcu_assign_pointer(newg->spare->res_table, old_res_table);
+	}
+
 	/* update parents - used by nexthop code for cleanup */
 	for (i = 0; i < newg->num_nh; i++)
 		newg->nh_entries[i].nh_parent = old;
 
 	rcu_assign_pointer(old->nh_grp, newg);
 
+	if (newg->resilient) {
+		rcu_assign_pointer(oldg->res_table, tmp_table);
+		rcu_assign_pointer(oldg->spare->res_table, tmp_table);
+	}
+
 	for (i = 0; i < oldg->num_nh; i++)
 		oldg->nh_entries[i].nh_parent = new;
 
@@ -1156,6 +2011,71 @@ static void nh_group_v4_update(struct nh_group *nhg)
 	nhg->has_v4 = has_v4;
 }
 
+static int replace_nexthop_single_notify_res(struct net *net,
+					     struct nh_res_table *res_table,
+					     struct nexthop *old,
+					     struct nh_info *oldi,
+					     struct nh_info *newi,
+					     struct netlink_ext_ack *extack)
+{
+	u32 nhg_id = res_table->nhg_id;
+	int err;
+	u16 i;
+
+	for (i = 0; i < res_table->num_nh_buckets; i++) {
+		struct nh_res_bucket *bucket = &res_table->nh_buckets[i];
+		struct nh_grp_entry *nhge;
+
+		nhge = rtnl_dereference(bucket->nh_entry);
+		if (nhge->nh == old) {
+			err = __call_nexthop_res_bucket_notifiers(net, nhg_id,
+								  i, true,
+								  oldi, newi,
+								  extack);
+			if (err)
+				goto err_notify;
+		}
+	}
+
+	return 0;
+
+err_notify:
+	while (i-- > 0) {
+		struct nh_res_bucket *bucket = &res_table->nh_buckets[i];
+		struct nh_grp_entry *nhge;
+
+		nhge = rtnl_dereference(bucket->nh_entry);
+		if (nhge->nh == old)
+			__call_nexthop_res_bucket_notifiers(net, nhg_id, i,
+							    true, newi, oldi,
+							    extack);
+	}
+	return err;
+}
+
+static int replace_nexthop_single_notify(struct net *net,
+					 struct nexthop *group_nh,
+					 struct nexthop *old,
+					 struct nh_info *oldi,
+					 struct nh_info *newi,
+					 struct netlink_ext_ack *extack)
+{
+	struct nh_group *nhg = rtnl_dereference(group_nh->nh_grp);
+	struct nh_res_table *res_table;
+
+	if (nhg->hash_threshold) {
+		return call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE,
+					      group_nh, extack);
+	} else if (nhg->resilient) {
+		res_table = rtnl_dereference(nhg->res_table);
+		return replace_nexthop_single_notify_res(net, res_table,
+							 old, oldi, newi,
+							 extack);
+	}
+
+	return -EINVAL;
+}
+
 static int replace_nexthop_single(struct net *net, struct nexthop *old,
 				  struct nexthop *new,
 				  struct netlink_ext_ack *extack)
@@ -1198,8 +2118,8 @@ static int replace_nexthop_single(struct net *net, struct nexthop *old,
 	list_for_each_entry(nhge, &old->grp_list, nh_list) {
 		struct nexthop *nhp = nhge->nh_parent;
 
-		err = call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE, nhp,
-					     extack);
+		err = replace_nexthop_single_notify(net, nhp, old, oldi, newi,
+						    extack);
 		if (err)
 			goto err_notify;
 	}
@@ -1229,7 +2149,7 @@ err_notify:
 	list_for_each_entry_continue_reverse(nhge, &old->grp_list, nh_list) {
 		struct nexthop *nhp = nhge->nh_parent;
 
-		call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE, nhp, extack);
+		replace_nexthop_single_notify(net, nhp, old, newi, oldi, NULL);
 	}
 	call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE, old, extack);
 	return err;
@@ -1276,7 +2196,8 @@ static void nexthop_replace_notify(struct net *net, struct nexthop *nh,
 }
 
 static int replace_nexthop(struct net *net, struct nexthop *old,
-			   struct nexthop *new, struct netlink_ext_ack *extack)
+			   struct nexthop *new, const struct nh_config *cfg,
+			   struct netlink_ext_ack *extack)
 {
 	bool new_is_reject = false;
 	struct nh_grp_entry *nhge;
@@ -1319,7 +2240,7 @@ static int replace_nexthop(struct net *net, struct nexthop *old,
 	}
 
 	if (old->is_group)
-		err = replace_nexthop_grp(net, old, new, extack);
+		err = replace_nexthop_grp(net, old, new, cfg, extack);
 	else
 		err = replace_nexthop_single(net, old, new, extack);
 
@@ -1361,7 +2282,7 @@ static int insert_nexthop(struct net *net, struct nexthop *new_nh,
 		} else if (new_id > nh->id) {
 			pp = &next->rb_right;
 		} else if (replace) {
-			rc = replace_nexthop(net, nh, new_nh, extack);
+			rc = replace_nexthop(net, nh, new_nh, cfg, extack);
 			if (!rc) {
 				new_nh = nh; /* send notification with old nh */
 				replace_notify = 1;
@@ -1379,9 +2300,37 @@ static int insert_nexthop(struct net *net, struct nexthop *new_nh,
 		goto out;
 	}
 
+	if (new_nh->is_group) {
+		struct nh_group *nhg = rtnl_dereference(new_nh->nh_grp);
+		struct nh_res_table *res_table;
+
+		if (nhg->resilient) {
+			res_table = rtnl_dereference(nhg->res_table);
+
+			/* Not passing the number of buckets is OK when
+			 * replacing, but not when creating a new group.
+			 */
+			if (!cfg->nh_grp_res_has_num_buckets) {
+				NL_SET_ERR_MSG(extack, "Number of buckets not specified for nexthop group insertion");
+				rc = -EINVAL;
+				goto out;
+			}
+
+			nh_res_group_rebalance(nhg, res_table);
+
+			/* Do not send bucket notifications, we do full
+			 * notification below.
+			 */
+			nh_res_table_upkeep(res_table, false, false);
+		}
+	}
+
 	rb_link_node_rcu(&new_nh->rb_node, parent, pp);
 	rb_insert_color(&new_nh->rb_node, root);
 
+	/* The initial insertion is a full notification for hash-threshold as
+	 * well as resilient groups.
+	 */
 	rc = call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE, new_nh, extack);
 	if (rc)
 		rb_erase(&new_nh->rb_node, &net->nexthop.rb_root);
@@ -1441,6 +2390,7 @@ static struct nexthop *nexthop_create_group(struct net *net,
 	u16 num_nh = nla_len(grps_attr) / sizeof(*entry);
 	struct nh_group *nhg;
 	struct nexthop *nh;
+	int err;
 	int i;
 
 	if (WARN_ON(!num_nh))
@@ -1472,8 +2422,10 @@ static struct nexthop *nexthop_create_group(struct net *net,
 		struct nh_info *nhi;
 
 		nhe = nexthop_find_by_id(net, entry[i].id);
-		if (!nexthop_get(nhe))
+		if (!nexthop_get(nhe)) {
+			err = -ENOENT;
 			goto out_no_nh;
+		}
 
 		nhi = rtnl_dereference(nhe->nh_info);
 		if (nhi->family == AF_INET)
@@ -1485,13 +2437,28 @@ static struct nexthop *nexthop_create_group(struct net *net,
 		nhg->nh_entries[i].nh_parent = nh;
 	}
 
-	if (cfg->nh_grp_type == NEXTHOP_GRP_TYPE_MPATH)
-		nhg->mpath = 1;
+	if (cfg->nh_grp_type == NEXTHOP_GRP_TYPE_MPATH) {
+		nhg->hash_threshold = 1;
+		nhg->is_multipath = true;
+	} else if (cfg->nh_grp_type == NEXTHOP_GRP_TYPE_RES) {
+		struct nh_res_table *res_table;
+
+		res_table = nexthop_res_table_alloc(net, cfg->nh_id, cfg);
+		if (!res_table) {
+			err = -ENOMEM;
+			goto out_no_nh;
+		}
+
+		rcu_assign_pointer(nhg->spare->res_table, res_table);
+		rcu_assign_pointer(nhg->res_table, res_table);
+		nhg->resilient = true;
+		nhg->is_multipath = true;
+	}
 
-	WARN_ON_ONCE(nhg->mpath != 1);
+	WARN_ON_ONCE(nhg->hash_threshold + nhg->resilient != 1);
 
-	if (nhg->mpath)
-		nh_group_rebalance(nhg);
+	if (nhg->hash_threshold)
+		nh_hthr_group_rebalance(nhg);
 
 	if (cfg->nh_fdb)
 		nhg->fdb_nh = 1;
@@ -1510,7 +2477,7 @@ out_no_nh:
 	kfree(nhg);
 	kfree(nh);
 
-	return ERR_PTR(-ENOENT);
+	return ERR_PTR(err);
 }
 
 static int nh_create_ipv4(struct net *net, struct nexthop *nh,
@@ -1680,6 +2647,70 @@ static struct nexthop *nexthop_add(struct net *net, struct nh_config *cfg,
 	return nh;
 }
 
+static int rtm_nh_get_timer(struct nlattr *attr, unsigned long fallback,
+			    unsigned long *timer_p, bool *has_p,
+			    struct netlink_ext_ack *extack)
+{
+	unsigned long timer;
+	u32 value;
+
+	if (!attr) {
+		*timer_p = fallback;
+		*has_p = false;
+		return 0;
+	}
+
+	value = nla_get_u32(attr);
+	timer = clock_t_to_jiffies(value);
+	if (timer == ~0UL) {
+		NL_SET_ERR_MSG(extack, "Timer value too large");
+		return -EINVAL;
+	}
+
+	*timer_p = timer;
+	*has_p = true;
+	return 0;
+}
+
+static int rtm_to_nh_config_grp_res(struct nlattr *res, struct nh_config *cfg,
+				    struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[ARRAY_SIZE(rtm_nh_res_policy_new)] = {};
+	int err;
+
+	if (res) {
+		err = nla_parse_nested(tb,
+				       ARRAY_SIZE(rtm_nh_res_policy_new) - 1,
+				       res, rtm_nh_res_policy_new, extack);
+		if (err < 0)
+			return err;
+	}
+
+	if (tb[NHA_RES_GROUP_BUCKETS]) {
+		cfg->nh_grp_res_num_buckets =
+			nla_get_u16(tb[NHA_RES_GROUP_BUCKETS]);
+		cfg->nh_grp_res_has_num_buckets = true;
+		if (!cfg->nh_grp_res_num_buckets) {
+			NL_SET_ERR_MSG(extack, "Number of buckets needs to be non-0");
+			return -EINVAL;
+		}
+	}
+
+	err = rtm_nh_get_timer(tb[NHA_RES_GROUP_IDLE_TIMER],
+			       NH_RES_DEFAULT_IDLE_TIMER,
+			       &cfg->nh_grp_res_idle_timer,
+			       &cfg->nh_grp_res_has_idle_timer,
+			       extack);
+	if (err)
+		return err;
+
+	return rtm_nh_get_timer(tb[NHA_RES_GROUP_UNBALANCED_TIMER],
+				NH_RES_DEFAULT_UNBALANCED_TIMER,
+				&cfg->nh_grp_res_unbalanced_timer,
+				&cfg->nh_grp_res_has_unbalanced_timer,
+				extack);
+}
+
 static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
 			    struct nlmsghdr *nlh, struct nh_config *cfg,
 			    struct netlink_ext_ack *extack)
@@ -1758,7 +2789,14 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
 			NL_SET_ERR_MSG(extack, "Invalid group type");
 			goto out;
 		}
-		err = nh_check_attr_group(net, tb, ARRAY_SIZE(tb), extack);
+		err = nh_check_attr_group(net, tb, ARRAY_SIZE(tb),
+					  cfg->nh_grp_type, extack);
+		if (err)
+			goto out;
+
+		if (cfg->nh_grp_type == NEXTHOP_GRP_TYPE_RES)
+			err = rtm_to_nh_config_grp_res(tb[NHA_RES_GROUP],
+						       cfg, extack);
 
 		/* no other attributes should be set */
 		goto out;
@@ -1983,10 +3021,12 @@ errout_free:
 }
 
 struct nh_dump_filter {
+	u32 nh_id;
 	int dev_idx;
 	int master_idx;
 	bool group_filter;
 	bool fdb_filter;
+	u32 res_bucket_nh_id;
 };
 
 static bool nh_dump_filtered(struct nexthop *nh,
@@ -2100,26 +3140,24 @@ static int rtm_dump_walk_nexthops(struct sk_buff *skb,
 				  void *data)
 {
 	struct rb_node *node;
-	int idx = 0, s_idx;
+	int s_idx;
 	int err;
 
 	s_idx = ctx->idx;
 	for (node = rb_first(root); node; node = rb_next(node)) {
 		struct nexthop *nh;
 
-		if (idx < s_idx)
-			goto cont;
-
 		nh = rb_entry(node, struct nexthop, rb_node);
-		ctx->idx = idx;
+		if (nh->id < s_idx)
+			continue;
+
+		ctx->idx = nh->id;
 		err = nh_cb(skb, cb, nh, data);
 		if (err)
 			return err;
-cont:
-		idx++;
 	}
 
-	ctx->idx = idx;
+	ctx->idx++;
 	return 0;
 }
 
@@ -2166,6 +3204,318 @@ out_err:
 	return err;
 }
 
+static struct nexthop *
+nexthop_find_group_resilient(struct net *net, u32 id,
+			     struct netlink_ext_ack *extack)
+{
+	struct nh_group *nhg;
+	struct nexthop *nh;
+
+	nh = nexthop_find_by_id(net, id);
+	if (!nh)
+		return ERR_PTR(-ENOENT);
+
+	if (!nh->is_group) {
+		NL_SET_ERR_MSG(extack, "Not a nexthop group");
+		return ERR_PTR(-EINVAL);
+	}
+
+	nhg = rtnl_dereference(nh->nh_grp);
+	if (!nhg->resilient) {
+		NL_SET_ERR_MSG(extack, "Nexthop group not of type resilient");
+		return ERR_PTR(-EINVAL);
+	}
+
+	return nh;
+}
+
+static int nh_valid_dump_nhid(struct nlattr *attr, u32 *nh_id_p,
+			      struct netlink_ext_ack *extack)
+{
+	u32 idx;
+
+	if (attr) {
+		idx = nla_get_u32(attr);
+		if (!idx) {
+			NL_SET_ERR_MSG(extack, "Invalid nexthop id");
+			return -EINVAL;
+		}
+		*nh_id_p = idx;
+	} else {
+		*nh_id_p = 0;
+	}
+
+	return 0;
+}
+
+static int nh_valid_dump_bucket_req(const struct nlmsghdr *nlh,
+				    struct nh_dump_filter *filter,
+				    struct netlink_callback *cb)
+{
+	struct nlattr *res_tb[ARRAY_SIZE(rtm_nh_res_bucket_policy_dump)];
+	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_dump_bucket)];
+	int err;
+
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb,
+			  ARRAY_SIZE(rtm_nh_policy_dump_bucket) - 1,
+			  rtm_nh_policy_dump_bucket, NULL);
+	if (err < 0)
+		return err;
+
+	err = nh_valid_dump_nhid(tb[NHA_ID], &filter->nh_id, cb->extack);
+	if (err)
+		return err;
+
+	if (tb[NHA_RES_BUCKET]) {
+		size_t max = ARRAY_SIZE(rtm_nh_res_bucket_policy_dump) - 1;
+
+		err = nla_parse_nested(res_tb, max,
+				       tb[NHA_RES_BUCKET],
+				       rtm_nh_res_bucket_policy_dump,
+				       cb->extack);
+		if (err < 0)
+			return err;
+
+		err = nh_valid_dump_nhid(res_tb[NHA_RES_BUCKET_NH_ID],
+					 &filter->res_bucket_nh_id,
+					 cb->extack);
+		if (err)
+			return err;
+	}
+
+	return __nh_valid_dump_req(nlh, tb, filter, cb->extack);
+}
+
+struct rtm_dump_res_bucket_ctx {
+	struct rtm_dump_nh_ctx nh;
+	u16 bucket_index;
+	u32 done_nh_idx; /* 1 + the index of the last fully processed NH. */
+};
+
+static struct rtm_dump_res_bucket_ctx *
+rtm_dump_res_bucket_ctx(struct netlink_callback *cb)
+{
+	struct rtm_dump_res_bucket_ctx *ctx = (void *)cb->ctx;
+
+	BUILD_BUG_ON(sizeof(*ctx) > sizeof(cb->ctx));
+	return ctx;
+}
+
+struct rtm_dump_nexthop_bucket_data {
+	struct rtm_dump_res_bucket_ctx *ctx;
+	struct nh_dump_filter filter;
+};
+
+static int rtm_dump_nexthop_bucket_nh(struct sk_buff *skb,
+				      struct netlink_callback *cb,
+				      struct nexthop *nh,
+				      struct rtm_dump_nexthop_bucket_data *dd)
+{
+	u32 portid = NETLINK_CB(cb->skb).portid;
+	struct nhmsg *nhm = nlmsg_data(cb->nlh);
+	struct nh_res_table *res_table;
+	struct nh_group *nhg;
+	u16 bucket_index;
+	int err;
+
+	if (dd->ctx->nh.idx < dd->ctx->done_nh_idx)
+		return 0;
+
+	nhg = rtnl_dereference(nh->nh_grp);
+	res_table = rtnl_dereference(nhg->res_table);
+	for (bucket_index = dd->ctx->bucket_index;
+	     bucket_index < res_table->num_nh_buckets;
+	     bucket_index++) {
+		struct nh_res_bucket *bucket;
+		struct nh_grp_entry *nhge;
+
+		bucket = &res_table->nh_buckets[bucket_index];
+		nhge = rtnl_dereference(bucket->nh_entry);
+		if (nh_dump_filtered(nhge->nh, &dd->filter, nhm->nh_family))
+			continue;
+
+		if (dd->filter.res_bucket_nh_id &&
+		    dd->filter.res_bucket_nh_id != nhge->nh->id)
+			continue;
+
+		err = nh_fill_res_bucket(skb, nh, bucket, bucket_index,
+					 RTM_NEWNEXTHOPBUCKET, portid,
+					 cb->nlh->nlmsg_seq, NLM_F_MULTI,
+					 cb->extack);
+		if (err < 0) {
+			if (likely(skb->len))
+				goto out;
+			goto out_err;
+		}
+	}
+
+	dd->ctx->done_nh_idx = dd->ctx->nh.idx + 1;
+	bucket_index = 0;
+
+out:
+	err = skb->len;
+out_err:
+	dd->ctx->bucket_index = bucket_index;
+	return err;
+}
+
+static int rtm_dump_nexthop_bucket_cb(struct sk_buff *skb,
+				      struct netlink_callback *cb,
+				      struct nexthop *nh, void *data)
+{
+	struct rtm_dump_nexthop_bucket_data *dd = data;
+	struct nh_group *nhg;
+
+	if (!nh->is_group)
+		return 0;
+
+	nhg = rtnl_dereference(nh->nh_grp);
+	if (!nhg->resilient)
+		return 0;
+
+	return rtm_dump_nexthop_bucket_nh(skb, cb, nh, dd);
+}
+
+/* rtnl */
+static int rtm_dump_nexthop_bucket(struct sk_buff *skb,
+				   struct netlink_callback *cb)
+{
+	struct rtm_dump_res_bucket_ctx *ctx = rtm_dump_res_bucket_ctx(cb);
+	struct rtm_dump_nexthop_bucket_data dd = { .ctx = ctx };
+	struct net *net = sock_net(skb->sk);
+	struct nexthop *nh;
+	int err;
+
+	err = nh_valid_dump_bucket_req(cb->nlh, &dd.filter, cb);
+	if (err)
+		return err;
+
+	if (dd.filter.nh_id) {
+		nh = nexthop_find_group_resilient(net, dd.filter.nh_id,
+						  cb->extack);
+		if (IS_ERR(nh))
+			return PTR_ERR(nh);
+		err = rtm_dump_nexthop_bucket_nh(skb, cb, nh, &dd);
+	} else {
+		struct rb_root *root = &net->nexthop.rb_root;
+
+		err = rtm_dump_walk_nexthops(skb, cb, root, &ctx->nh,
+					     &rtm_dump_nexthop_bucket_cb, &dd);
+	}
+
+	if (err < 0) {
+		if (likely(skb->len))
+			goto out;
+		goto out_err;
+	}
+
+out:
+	err = skb->len;
+out_err:
+	cb->seq = net->nexthop.seq;
+	nl_dump_check_consistent(cb, nlmsg_hdr(skb));
+	return err;
+}
+
+static int nh_valid_get_bucket_req_res_bucket(struct nlattr *res,
+					      u16 *bucket_index,
+					      struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[ARRAY_SIZE(rtm_nh_res_bucket_policy_get)];
+	int err;
+
+	err = nla_parse_nested(tb, ARRAY_SIZE(rtm_nh_res_bucket_policy_get) - 1,
+			       res, rtm_nh_res_bucket_policy_get, extack);
+	if (err < 0)
+		return err;
+
+	if (!tb[NHA_RES_BUCKET_INDEX]) {
+		NL_SET_ERR_MSG(extack, "Bucket index is missing");
+		return -EINVAL;
+	}
+
+	*bucket_index = nla_get_u16(tb[NHA_RES_BUCKET_INDEX]);
+	return 0;
+}
+
+static int nh_valid_get_bucket_req(const struct nlmsghdr *nlh,
+				   u32 *id, u16 *bucket_index,
+				   struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_get_bucket)];
+	int err;
+
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb,
+			  ARRAY_SIZE(rtm_nh_policy_get_bucket) - 1,
+			  rtm_nh_policy_get_bucket, extack);
+	if (err < 0)
+		return err;
+
+	err = __nh_valid_get_del_req(nlh, tb, id, extack);
+	if (err)
+		return err;
+
+	if (!tb[NHA_RES_BUCKET]) {
+		NL_SET_ERR_MSG(extack, "Bucket information is missing");
+		return -EINVAL;
+	}
+
+	err = nh_valid_get_bucket_req_res_bucket(tb[NHA_RES_BUCKET],
+						 bucket_index, extack);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+/* rtnl */
+static int rtm_get_nexthop_bucket(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+				  struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(in_skb->sk);
+	struct nh_res_table *res_table;
+	struct sk_buff *skb = NULL;
+	struct nh_group *nhg;
+	struct nexthop *nh;
+	u16 bucket_index;
+	int err;
+	u32 id;
+
+	err = nh_valid_get_bucket_req(nlh, &id, &bucket_index, extack);
+	if (err)
+		return err;
+
+	nh = nexthop_find_group_resilient(net, id, extack);
+	if (IS_ERR(nh))
+		return PTR_ERR(nh);
+
+	nhg = rtnl_dereference(nh->nh_grp);
+	res_table = rtnl_dereference(nhg->res_table);
+	if (bucket_index >= res_table->num_nh_buckets) {
+		NL_SET_ERR_MSG(extack, "Bucket index out of bounds");
+		return -ENOENT;
+	}
+
+	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!skb)
+		return -ENOBUFS;
+
+	err = nh_fill_res_bucket(skb, nh, &res_table->nh_buckets[bucket_index],
+				 bucket_index, RTM_NEWNEXTHOPBUCKET,
+				 NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
+				 0, extack);
+	if (err < 0) {
+		WARN_ON(err == -EMSGSIZE);
+		goto errout_free;
+	}
+
+	return rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
+
+errout_free:
+	kfree_skb(skb);
+	return err;
+}
+
 static void nexthop_sync_mtu(struct net_device *dev, u32 orig_mtu)
 {
 	unsigned int hash = nh_dev_hashfn(dev->ifindex);
@@ -2277,6 +3627,75 @@ out:
 }
 EXPORT_SYMBOL(nexthop_set_hw_flags);
 
+void nexthop_bucket_set_hw_flags(struct net *net, u32 id, u16 bucket_index,
+				 bool offload, bool trap)
+{
+	struct nh_res_table *res_table;
+	struct nh_res_bucket *bucket;
+	struct nexthop *nexthop;
+	struct nh_group *nhg;
+
+	rcu_read_lock();
+
+	nexthop = nexthop_find_by_id(net, id);
+	if (!nexthop || !nexthop->is_group)
+		goto out;
+
+	nhg = rcu_dereference(nexthop->nh_grp);
+	if (!nhg->resilient)
+		goto out;
+
+	if (bucket_index >= nhg->res_table->num_nh_buckets)
+		goto out;
+
+	res_table = rcu_dereference(nhg->res_table);
+	bucket = &res_table->nh_buckets[bucket_index];
+	bucket->nh_flags &= ~(RTNH_F_OFFLOAD | RTNH_F_TRAP);
+	if (offload)
+		bucket->nh_flags |= RTNH_F_OFFLOAD;
+	if (trap)
+		bucket->nh_flags |= RTNH_F_TRAP;
+
+out:
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(nexthop_bucket_set_hw_flags);
+
+void nexthop_res_grp_activity_update(struct net *net, u32 id, u16 num_buckets,
+				     unsigned long *activity)
+{
+	struct nh_res_table *res_table;
+	struct nexthop *nexthop;
+	struct nh_group *nhg;
+	u16 i;
+
+	rcu_read_lock();
+
+	nexthop = nexthop_find_by_id(net, id);
+	if (!nexthop || !nexthop->is_group)
+		goto out;
+
+	nhg = rcu_dereference(nexthop->nh_grp);
+	if (!nhg->resilient)
+		goto out;
+
+	/* Instead of silently ignoring some buckets, demand that the sizes
+	 * be the same.
+	 */
+	res_table = rcu_dereference(nhg->res_table);
+	if (num_buckets != res_table->num_nh_buckets)
+		goto out;
+
+	for (i = 0; i < num_buckets; i++) {
+		if (test_bit(i, activity))
+			nh_res_bucket_set_busy(&res_table->nh_buckets[i]);
+	}
+
+out:
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(nexthop_res_grp_activity_update);
+
 static void __net_exit nexthop_net_exit(struct net *net)
 {
 	rtnl_lock();
@@ -2320,6 +3739,9 @@ static int __init nexthop_init(void)
 	rtnl_register(PF_INET6, RTM_NEWNEXTHOP, rtm_new_nexthop, NULL, 0);
 	rtnl_register(PF_INET6, RTM_GETNEXTHOP, NULL, rtm_dump_nexthop, 0);
 
+	rtnl_register(PF_UNSPEC, RTM_GETNEXTHOPBUCKET, rtm_get_nexthop_bucket,
+		      rtm_dump_nexthop_bucket, 0);
+
 	return 0;
 }
 subsys_initcall(nexthop_init);