ipv4: Use accessors for fib_info nexthop data

Use helpers to access fib_nh and fib_nhs fields of a fib_info. Drop the
fib_dev macro which is an alias for the first nexthop. Replacements:

  fi->fib_dev    --> fib_info_nh(fi, 0)->fib_nh_dev
  fi->fib_nh     --> fib_info_nh(fi, 0)
  fi->fib_nh[i]  --> fib_info_nh(fi, i)
  fi->fib_nhs    --> fib_info_num_path(fi)

where fib_info_nh(fi, i) returns fi->fib_nh[nhsel] and fib_info_num_path
returns fi->fib_nhs.

Move the existing fib_info_nhc to nexthop.h and define the new ones
there. A later patch adds a check if a fib_info uses a nexthop object,
and defining the helpers in nexthop.h avoid circular header
dependencies.

After this all remaining open coded references to fi->fib_nhs and
fi->fib_nh are in:
- fib_create_info and helpers used to lookup an existing fib_info
  entry, and
- the netdev event functions fib_sync_down_dev and fib_sync_up.

The latter two will not be reused for nexthops, and the fib_create_info
will be updated to handle a nexthop in a fib_info.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/lag_mp.c

@@ -2,6 +2,7 @@
 /* Copyright (c) 2019 Mellanox Technologies. */
 
 #include <linux/netdevice.h>
+#include <net/nexthop.h>
 #include "lag.h"
 #include "lag_mp.h"
 #include "mlx5_core.h"
@@ -110,6 +111,8 @@ static void mlx5_lag_fib_route_event(struct mlx5_lag *ldev,
 				     struct fib_info *fi)
 {
 	struct lag_mp *mp = &ldev->lag_mp;
+	struct fib_nh *fib_nh0, *fib_nh1;
+	unsigned int nhs;
 
 	/* Handle delete event */
 	if (event == FIB_EVENT_ENTRY_DEL) {
@@ -120,24 +123,28 @@ static void mlx5_lag_fib_route_event(struct mlx5_lag *ldev,
 	}
 
 	/* Handle add/replace event */
-	if (fi->fib_nhs == 1) {
+	nhs = fib_info_num_path(fi);
+	if (nhs == 1) {
 		if (__mlx5_lag_is_active(ldev)) {
-			struct net_device *nh_dev = fi->fib_nh[0].fib_nh_dev;
+			struct fib_nh *nh = fib_info_nh(fi, 0);
+			struct net_device *nh_dev = nh->fib_nh_dev;
 			int i = mlx5_lag_dev_get_netdev_idx(ldev, nh_dev);
 
 			mlx5_lag_set_port_affinity(ldev, ++i);
 		}
 		return;
 	}
 
-	if (fi->fib_nhs != 2)
+	if (nhs != 2)
 		return;
 
 	/* Verify next hops are ports of the same hca */
-	if (!(fi->fib_nh[0].fib_nh_dev == ldev->pf[0].netdev &&
-	      fi->fib_nh[1].fib_nh_dev == ldev->pf[1].netdev) &&
-	    !(fi->fib_nh[0].fib_nh_dev == ldev->pf[1].netdev &&
-	      fi->fib_nh[1].fib_nh_dev == ldev->pf[0].netdev)) {
+	fib_nh0 = fib_info_nh(fi, 0);
+	fib_nh1 = fib_info_nh(fi, 1);
+	if (!(fib_nh0->fib_nh_dev == ldev->pf[0].netdev &&
+	      fib_nh1->fib_nh_dev == ldev->pf[1].netdev) &&
+	    !(fib_nh0->fib_nh_dev == ldev->pf[1].netdev &&
+	      fib_nh1->fib_nh_dev == ldev->pf[0].netdev)) {
 		mlx5_core_warn(ldev->pf[0].dev, "Multipath offload require two ports of the same HCA\n");
 		return;
 	}
@@ -174,7 +181,7 @@ static void mlx5_lag_fib_nexthop_event(struct mlx5_lag *ldev,
 			mlx5_lag_set_port_affinity(ldev, i);
 		}
 	} else if (event == FIB_EVENT_NH_ADD &&
-		   fi->fib_nhs == 2) {
+		   fib_info_num_path(fi) == 2) {
 		mlx5_lag_set_port_affinity(ldev, 0);
 	}
 }
@@ -238,6 +245,7 @@ static int mlx5_lag_fib_event(struct notifier_block *nb,
 	struct mlx5_fib_event_work *fib_work;
 	struct fib_entry_notifier_info *fen_info;
 	struct fib_nh_notifier_info *fnh_info;
+	struct net_device *fib_dev;
 	struct fib_info *fi;
 
 	if (info->family != AF_INET)
@@ -254,8 +262,9 @@ static int mlx5_lag_fib_event(struct notifier_block *nb,
 		fen_info = container_of(info, struct fib_entry_notifier_info,
 					info);
 		fi = fen_info->fi;
-		if (fi->fib_dev != ldev->pf[0].netdev &&
-		    fi->fib_dev != ldev->pf[1].netdev) {
+		fib_dev = fib_info_nh(fen_info->fi, 0)->fib_nh_dev;
+		if (fib_dev != ldev->pf[0].netdev &&
+		    fib_dev != ldev->pf[1].netdev) {
 			return NOTIFY_DONE;
 		}
 		fib_work = mlx5_lag_init_fib_work(ldev, event);

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c

@@ -21,6 +21,7 @@
 #include <net/arp.h>
 #include <net/ip_fib.h>
 #include <net/ip6_fib.h>
+#include <net/nexthop.h>
 #include <net/fib_rules.h>
 #include <net/ip_tunnels.h>
 #include <net/l3mdev.h>
@@ -3816,35 +3817,37 @@ static void mlxsw_sp_nexthop_rif_gone_sync(struct mlxsw_sp *mlxsw_sp,
 }
 
 static bool mlxsw_sp_fi_is_gateway(const struct mlxsw_sp *mlxsw_sp,
-				   const struct fib_info *fi)
+				   struct fib_info *fi)
 {
-	return fi->fib_nh->fib_nh_scope == RT_SCOPE_LINK ||
-	       mlxsw_sp_nexthop4_ipip_type(mlxsw_sp, fi->fib_nh, NULL);
+	const struct fib_nh *nh = fib_info_nh(fi, 0);
+
+	return nh->fib_nh_scope == RT_SCOPE_LINK ||
+	       mlxsw_sp_nexthop4_ipip_type(mlxsw_sp, nh, NULL);
 }
 
 static struct mlxsw_sp_nexthop_group *
 mlxsw_sp_nexthop4_group_create(struct mlxsw_sp *mlxsw_sp, struct fib_info *fi)
 {
+	unsigned int nhs = fib_info_num_path(fi);
 	struct mlxsw_sp_nexthop_group *nh_grp;
 	struct mlxsw_sp_nexthop *nh;
 	struct fib_nh *fib_nh;
 	int i;
 	int err;
 
-	nh_grp = kzalloc(struct_size(nh_grp, nexthops, fi->fib_nhs),
-			 GFP_KERNEL);
+	nh_grp = kzalloc(struct_size(nh_grp, nexthops, nhs), GFP_KERNEL);
 	if (!nh_grp)
 		return ERR_PTR(-ENOMEM);
 	nh_grp->priv = fi;
 	INIT_LIST_HEAD(&nh_grp->fib_list);
 	nh_grp->neigh_tbl = &arp_tbl;
 
 	nh_grp->gateway = mlxsw_sp_fi_is_gateway(mlxsw_sp, fi);
-	nh_grp->count = fi->fib_nhs;
+	nh_grp->count = nhs;
 	fib_info_hold(fi);
 	for (i = 0; i < nh_grp->count; i++) {
 		nh = &nh_grp->nexthops[i];
-		fib_nh = &fi->fib_nh[i];
+		fib_nh = fib_info_nh(fi, i);
 		err = mlxsw_sp_nexthop4_init(mlxsw_sp, nh_grp, nh, fib_nh);
 		if (err)
 			goto err_nexthop4_init;
@@ -4282,9 +4285,9 @@ mlxsw_sp_fib4_entry_type_set(struct mlxsw_sp *mlxsw_sp,
 			     const struct fib_entry_notifier_info *fen_info,
 			     struct mlxsw_sp_fib_entry *fib_entry)
 {
+	struct net_device *dev = fib_info_nh(fen_info->fi, 0)->fib_nh_dev;
 	union mlxsw_sp_l3addr dip = { .addr4 = htonl(fen_info->dst) };
 	u32 tb_id = mlxsw_sp_fix_tb_id(fen_info->tb_id);
-	struct net_device *dev = fen_info->fi->fib_dev;
 	struct mlxsw_sp_ipip_entry *ipip_entry;
 	struct fib_info *fi = fen_info->fi;
 

drivers/net/ethernet/rocker/rocker_ofdpa.c

@@ -22,6 +22,7 @@
 #include <net/neighbour.h>
 #include <net/switchdev.h>
 #include <net/ip_fib.h>
+#include <net/nexthop.h>
 #include <net/arp.h>
 
 #include "rocker.h"
@@ -2286,8 +2287,8 @@ static int ofdpa_port_fib_ipv4(struct ofdpa_port *ofdpa_port,  __be32 dst,
 
 	/* XXX support ECMP */
 
-	nh = fi->fib_nh;
-	nh_on_port = (fi->fib_dev == ofdpa_port->dev);
+	nh = fib_info_nh(fi, 0);
+	nh_on_port = (nh->fib_nh_dev == ofdpa_port->dev);
 	has_gw = !!nh->fib_nh_gw4;
 
 	if (has_gw && nh_on_port) {
@@ -2737,19 +2738,21 @@ static int ofdpa_fib4_add(struct rocker *rocker,
 {
 	struct ofdpa *ofdpa = rocker->wpriv;
 	struct ofdpa_port *ofdpa_port;
+	struct fib_nh *nh;
 	int err;
 
 	if (ofdpa->fib_aborted)
 		return 0;
-	ofdpa_port = ofdpa_port_dev_lower_find(fen_info->fi->fib_dev, rocker);
+	nh = fib_info_nh(fen_info->fi, 0);
+	ofdpa_port = ofdpa_port_dev_lower_find(nh->fib_nh_dev, rocker);
 	if (!ofdpa_port)
 		return 0;
 	err = ofdpa_port_fib_ipv4(ofdpa_port, htonl(fen_info->dst),
 				  fen_info->dst_len, fen_info->fi,
 				  fen_info->tb_id, 0);
 	if (err)
 		return err;
-	fen_info->fi->fib_nh->fib_nh_flags |= RTNH_F_OFFLOAD;
+	nh->fib_nh_flags |= RTNH_F_OFFLOAD;
 	return 0;
 }
 
@@ -2758,13 +2761,15 @@ static int ofdpa_fib4_del(struct rocker *rocker,
 {
 	struct ofdpa *ofdpa = rocker->wpriv;
 	struct ofdpa_port *ofdpa_port;
+	struct fib_nh *nh;
 
 	if (ofdpa->fib_aborted)
 		return 0;
-	ofdpa_port = ofdpa_port_dev_lower_find(fen_info->fi->fib_dev, rocker);
+	nh = fib_info_nh(fen_info->fi, 0);
+	ofdpa_port = ofdpa_port_dev_lower_find(nh->fib_nh_dev, rocker);
 	if (!ofdpa_port)
 		return 0;
-	fen_info->fi->fib_nh->fib_nh_flags &= ~RTNH_F_OFFLOAD;
+	nh->fib_nh_flags &= ~RTNH_F_OFFLOAD;
 	return ofdpa_port_fib_ipv4(ofdpa_port, htonl(fen_info->dst),
 				   fen_info->dst_len, fen_info->fi,
 				   fen_info->tb_id, OFDPA_OP_FLAG_REMOVE);
@@ -2784,14 +2789,16 @@ static void ofdpa_fib4_abort(struct rocker *rocker)
 
 	spin_lock_irqsave(&ofdpa->flow_tbl_lock, flags);
 	hash_for_each_safe(ofdpa->flow_tbl, bkt, tmp, flow_entry, entry) {
+		struct fib_nh *nh;
+
 		if (flow_entry->key.tbl_id !=
 		    ROCKER_OF_DPA_TABLE_ID_UNICAST_ROUTING)
 			continue;
-		ofdpa_port = ofdpa_port_dev_lower_find(flow_entry->fi->fib_dev,
-						       rocker);
+		nh = fib_info_nh(flow_entry->fi, 0);
+		ofdpa_port = ofdpa_port_dev_lower_find(nh->fib_nh_dev, rocker);
 		if (!ofdpa_port)
 			continue;
-		flow_entry->fi->fib_nh->fib_nh_flags &= ~RTNH_F_OFFLOAD;
+		nh->fib_nh_flags &= ~RTNH_F_OFFLOAD;
 		ofdpa_flow_tbl_del(ofdpa_port, OFDPA_OP_FLAG_REMOVE,
 				   flow_entry);
 	}

include/net/ip_fib.h

@@ -153,7 +153,6 @@ struct fib_info {
 	bool			nh_updated;
 	struct rcu_head		rcu;
 	struct fib_nh		fib_nh[0];
-#define fib_dev		fib_nh[0].fib_nh_dev
 };
 
 
@@ -190,11 +189,6 @@ struct fib_result_nl {
 	int             err;
 };
 
-static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel)
-{
-	return &fi->fib_nh[nhsel].nh_common;
-}
-
 #ifdef CONFIG_IP_MULTIPLE_TABLES
 #define FIB_TABLE_HASHSZ 256
 #else

include/net/nexthop.h

@@ -192,4 +192,19 @@ static inline bool nexthop_is_blackhole(const struct nexthop *nh)
 	nhi = rcu_dereference_rtnl(nh->nh_info);
 	return nhi->reject_nh;
 }
+
+static inline unsigned int fib_info_num_path(const struct fib_info *fi)
+{
+	return fi->fib_nhs;
+}
+
+static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel)
+{
+	return &fi->fib_nh[nhsel].nh_common;
+}
+
+static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel)
+{
+	return &fi->fib_nh[nhsel];
+}
 #endif

net/core/filter.c

@@ -66,6 +66,7 @@
 #include <net/inet_hashtables.h>
 #include <net/inet6_hashtables.h>
 #include <net/ip_fib.h>
+#include <net/nexthop.h>
 #include <net/flow.h>
 #include <net/arp.h>
 #include <net/ipv6.h>
@@ -4674,7 +4675,7 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
 	if (res.type != RTN_UNICAST)
 		return BPF_FIB_LKUP_RET_NOT_FWDED;
 
-	if (res.fi->fib_nhs > 1)
+	if (fib_info_num_path(res.fi) > 1)
 		fib_select_path(net, &res, &fl4, NULL);
 
 	if (check_mtu) {

net/ipv4/fib_frontend.c

@@ -43,6 +43,7 @@
 #include <net/sock.h>
 #include <net/arp.h>
 #include <net/ip_fib.h>
+#include <net/nexthop.h>
 #include <net/rtnetlink.h>
 #include <net/xfrm.h>
 #include <net/l3mdev.h>
@@ -234,7 +235,9 @@ static inline unsigned int __inet_dev_addr_type(struct net *net,
 	if (table) {
 		ret = RTN_UNICAST;
 		if (!fib_table_lookup(table, &fl4, &res, FIB_LOOKUP_NOREF)) {
-			if (!dev || dev == res.fi->fib_dev)
+			struct fib_nh *nh = fib_info_nh(res.fi, 0);
+
+			if (!dev || dev == nh->fib_nh_dev)
 				ret = res.type;
 		}
 	}
@@ -321,8 +324,8 @@ bool fib_info_nh_uses_dev(struct fib_info *fi, const struct net_device *dev)
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 	int ret;
 
-	for (ret = 0; ret < fi->fib_nhs; ret++) {
-		struct fib_nh *nh = &fi->fib_nh[ret];
+	for (ret = 0; ret < fib_info_num_path(fi); ret++) {
+		const struct fib_nh *nh = fib_info_nh(fi, ret);
 
 		if (nh->fib_nh_dev == dev) {
 			dev_match = true;
@@ -333,7 +336,7 @@ bool fib_info_nh_uses_dev(struct fib_info *fi, const struct net_device *dev)
 		}
 	}
 #else
-	if (fi->fib_nh[0].fib_nh_dev == dev)
+	if (fib_info_nh(fi, 0)->fib_nh_dev == dev)
 		dev_match = true;
 #endif
 

net/ipv4/fib_lookup.h

@@ -5,6 +5,7 @@
 #include <linux/types.h>
 #include <linux/list.h>
 #include <net/ip_fib.h>
+#include <net/nexthop.h>
 
 struct fib_alias {
 	struct hlist_node	fa_list;

net/ipv4/fib_rules.c

@@ -31,6 +31,7 @@
 #include <net/route.h>
 #include <net/tcp.h>
 #include <net/ip_fib.h>
+#include <net/nexthop.h>
 #include <net/fib_rules.h>
 
 struct fib4_rule {
@@ -145,8 +146,11 @@ static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg
 	struct fib_result *result = (struct fib_result *) arg->result;
 	struct net_device *dev = NULL;
 
-	if (result->fi)
-		dev = result->fi->fib_dev;
+	if (result->fi) {
+		struct fib_nh *nh = fib_info_nh(result->fi, 0);
+
+		dev = nh->fib_nh_dev;
+	}
 
 	/* do not accept result if the route does
 	 * not meet the required prefix length