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>

7 files changed, 71 insertions, 47 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index 55bfc941d17a..2ae72bbfa6d2 100644
--- a/net/core/filter.c
+++ b/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) {
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index c7cdb8d0d164..a4691360b395 100644
--- a/net/ipv4/fib_frontend.c
+++ b/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
 
diff --git a/net/ipv4/fib_lookup.h b/net/ipv4/fib_lookup.h
index 7945f0534db7..a68b5e21ec51 100644
--- a/net/ipv4/fib_lookup.h
+++ b/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;
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index cfec3af54c8d..ab06fd73b343 100644
--- a/net/ipv4/fib_rules.c
+++ b/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
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 78648072783e..a37ff07718a8 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -42,6 +42,7 @@
 #include <net/sock.h>
 #include <net/ip_fib.h>
 #include <net/ip6_fib.h>
+#include <net/nexthop.h>
 #include <net/netlink.h>
 #include <net/rtnh.h>
 #include <net/lwtunnel.h>
@@ -65,13 +66,13 @@ static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
 #define for_nexthops(fi) {						\
 	int nhsel; const struct fib_nh *nh;				\
 	for (nhsel = 0, nh = (fi)->fib_nh;				\
-	     nhsel < (fi)->fib_nhs;					\
+	     nhsel < fib_info_num_path((fi));				\
 	     nh++, nhsel++)
 
 #define change_nexthops(fi) {						\
 	int nhsel; struct fib_nh *nexthop_nh;				\
 	for (nhsel = 0,	nexthop_nh = (struct fib_nh *)((fi)->fib_nh);	\
-	     nhsel < (fi)->fib_nhs;					\
+	     nhsel < fib_info_num_path((fi));				\
 	     nexthop_nh++, nhsel++)
 
 #else /* CONFIG_IP_ROUTE_MULTIPATH */
@@ -271,11 +272,13 @@ void fib_release_info(struct fib_info *fi)
 	spin_unlock_bh(&fib_info_lock);
 }
 
-static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
+static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
 {
-	const struct fib_nh *onh = ofi->fib_nh;
+	const struct fib_nh *onh;
 
 	for_nexthops(fi) {
+		onh = fib_info_nh(ofi, nhsel);
+
 		if (nh->fib_nh_oif != onh->fib_nh_oif ||
 		    nh->fib_nh_gw_family != onh->fib_nh_gw_family ||
 		    nh->fib_nh_scope != onh->fib_nh_scope ||
@@ -296,8 +299,6 @@ static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
 		if (nh->fib_nh_gw_family == AF_INET6 &&
 		    ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
 			return -1;
-
-		onh++;
 	} endfor_nexthops(fi);
 	return 0;
 }
@@ -326,7 +327,7 @@ static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
 	return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 }
 
-static struct fib_info *fib_find_info(const struct fib_info *nfi)
+static struct fib_info *fib_find_info(struct fib_info *nfi)
 {
 	struct hlist_head *head;
 	struct fib_info *fi;
@@ -390,13 +391,14 @@ static inline size_t fib_nlmsg_size(struct fib_info *fi)
 			 + nla_total_size(4) /* RTA_PRIORITY */
 			 + nla_total_size(4) /* RTA_PREFSRC */
 			 + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
+	unsigned int nhs = fib_info_num_path(fi);
 
 	/* space for nested metrics */
 	payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 
-	if (fi->fib_nhs) {
+	if (nhs) {
 		size_t nh_encapsize = 0;
-		/* Also handles the special case fib_nhs == 1 */
+		/* Also handles the special case nhs == 1 */
 
 		/* each nexthop is packed in an attribute */
 		size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
@@ -416,8 +418,7 @@ static inline size_t fib_nlmsg_size(struct fib_info *fi)
 		} endfor_nexthops(fi);
 
 		/* all nexthops are packed in a nested attribute */
-		payload += nla_total_size((fi->fib_nhs * nhsize) +
-					  nh_encapsize);
+		payload += nla_total_size((nhs * nhsize) + nh_encapsize);
 
 	}
 
@@ -584,6 +585,7 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 {
 	struct net *net = fi->fib_net;
 	struct fib_config fib_cfg;
+	struct fib_nh *nh;
 	int ret;
 
 	change_nexthops(fi) {
@@ -646,24 +648,25 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 	} endfor_nexthops(fi);
 
 	ret = -EINVAL;
-	if (cfg->fc_oif && fi->fib_nh->fib_nh_oif != cfg->fc_oif) {
+	nh = fib_info_nh(fi, 0);
+	if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
 		NL_SET_ERR_MSG(extack,
 			       "Nexthop device index does not match RTA_OIF");
 		goto errout;
 	}
 	if (cfg->fc_gw_family) {
-		if (cfg->fc_gw_family != fi->fib_nh->fib_nh_gw_family ||
+		if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
 		    (cfg->fc_gw_family == AF_INET &&
-		     fi->fib_nh->fib_nh_gw4 != cfg->fc_gw4) ||
+		     nh->fib_nh_gw4 != cfg->fc_gw4) ||
 		    (cfg->fc_gw_family == AF_INET6 &&
-		     ipv6_addr_cmp(&fi->fib_nh->fib_nh_gw6, &cfg->fc_gw6))) {
+		     ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
 			NL_SET_ERR_MSG(extack,
 				       "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
 			goto errout;
 		}
 	}
 #ifdef CONFIG_IP_ROUTE_CLASSID
-	if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow) {
+	if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
 		NL_SET_ERR_MSG(extack,
 			       "Nexthop class id does not match RTA_FLOW");
 		goto errout;
@@ -679,7 +682,7 @@ static void fib_rebalance(struct fib_info *fi)
 	int total;
 	int w;
 
-	if (fi->fib_nhs < 2)
+	if (fib_info_num_path(fi) < 2)
 		return;
 
 	total = 0;
@@ -761,27 +764,29 @@ int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
 		return 1;
 
 	if (cfg->fc_oif || cfg->fc_gw_family) {
+		struct fib_nh *nh = fib_info_nh(fi, 0);
+
 		if (cfg->fc_encap) {
 			if (fib_encap_match(cfg->fc_encap_type, cfg->fc_encap,
-					    fi->fib_nh, cfg, extack))
+					    nh, cfg, extack))
 				return 1;
 		}
 #ifdef CONFIG_IP_ROUTE_CLASSID
 		if (cfg->fc_flow &&
-		    cfg->fc_flow != fi->fib_nh->nh_tclassid)
+		    cfg->fc_flow != nh->nh_tclassid)
 			return 1;
 #endif
-		if ((cfg->fc_oif && cfg->fc_oif != fi->fib_nh->fib_nh_oif) ||
+		if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
 		    (cfg->fc_gw_family &&
-		     cfg->fc_gw_family != fi->fib_nh->fib_nh_gw_family))
+		     cfg->fc_gw_family != nh->fib_nh_gw_family))
 			return 1;
 
 		if (cfg->fc_gw_family == AF_INET &&
-		    cfg->fc_gw4 != fi->fib_nh->fib_nh_gw4)
+		    cfg->fc_gw4 != nh->fib_nh_gw4)
 			return 1;
 
 		if (cfg->fc_gw_family == AF_INET6 &&
-		    ipv6_addr_cmp(&cfg->fc_gw6, &fi->fib_nh->fib_nh_gw6))
+		    ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
 			return 1;
 
 		return 0;
@@ -1366,7 +1371,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
 			goto err_inval;
 		}
 		nh->fib_nh_scope = RT_SCOPE_NOWHERE;
-		nh->fib_nh_dev = dev_get_by_index(net, fi->fib_nh->fib_nh_oif);
+		nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
 		err = -ENODEV;
 		if (!nh->fib_nh_dev)
 			goto failure;
@@ -1583,6 +1588,7 @@ int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
 		  u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
 		  struct fib_info *fi, unsigned int flags)
 {
+	unsigned int nhs = fib_info_num_path(fi);
 	struct nlmsghdr *nlh;
 	struct rtmsg *rtm;
 
@@ -1618,8 +1624,8 @@ int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
 	if (fi->fib_prefsrc &&
 	    nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
 		goto nla_put_failure;
-	if (fi->fib_nhs == 1) {
-		struct fib_nh *nh = &fi->fib_nh[0];
+	if (nhs == 1) {
+		const struct fib_nh *nh = fib_info_nh(fi, 0);
 		unsigned char flags = 0;
 
 		if (fib_nexthop_info(skb, &nh->nh_common, &flags, false) < 0)
@@ -1838,6 +1844,7 @@ static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
 
 	hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
 		struct fib_info *next_fi = fa->fa_info;
+		struct fib_nh *nh;
 
 		if (fa->fa_slen != slen)
 			continue;
@@ -1859,8 +1866,9 @@ static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
 		if (next_fi->fib_scope != res->scope ||
 		    fa->fa_type != RTN_UNICAST)
 			continue;
-		if (!next_fi->fib_nh[0].fib_nh_gw4 ||
-		    next_fi->fib_nh[0].fib_nh_scope != RT_SCOPE_LINK)
+
+		nh = fib_info_nh(next_fi, 0);
+		if (!nh->fib_nh_gw4 || nh->fib_nh_scope != RT_SCOPE_LINK)
 			continue;
 
 		fib_alias_accessed(fa);
@@ -2024,7 +2032,7 @@ void fib_select_path(struct net *net, struct fib_result *res,
 		goto check_saddr;
 
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
-	if (res->fi->fib_nhs > 1) {
+	if (fib_info_num_path(res->fi) > 1) {
 		int h = fib_multipath_hash(net, fl4, skb, NULL);
 
 		fib_select_multipath(res, h);
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index b53ecef89d59..5c8a4d21b8e0 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1469,7 +1469,7 @@ found:
 		}
 		if (fi->fib_flags & RTNH_F_DEAD)
 			continue;
-		for (nhsel = 0; nhsel < fi->fib_nhs; nhsel++) {
+		for (nhsel = 0; nhsel < fib_info_num_path(fi); nhsel++) {
 			struct fib_nh_common *nhc = fib_info_nhc(fi, nhsel);
 
 			if (nhc->nhc_flags & RTNH_F_DEAD)
@@ -2717,14 +2717,18 @@ static void fib_route_seq_stop(struct seq_file *seq, void *v)
 	rcu_read_unlock();
 }
 
-static unsigned int fib_flag_trans(int type, __be32 mask, const struct fib_info *fi)
+static unsigned int fib_flag_trans(int type, __be32 mask, struct fib_info *fi)
 {
 	unsigned int flags = 0;
 
 	if (type == RTN_UNREACHABLE || type == RTN_PROHIBIT)
 		flags = RTF_REJECT;
-	if (fi && fi->fib_nh->fib_nh_gw4)
-		flags |= RTF_GATEWAY;
+	if (fi) {
+		const struct fib_nh *nh = fib_info_nh(fi, 0);
+
+		if (nh->fib_nh_gw4)
+			flags |= RTF_GATEWAY;
+	}
 	if (mask == htonl(0xFFFFFFFF))
 		flags |= RTF_HOST;
 	flags |= RTF_UP;
@@ -2755,7 +2759,7 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
 	prefix = htonl(l->key);
 
 	hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
-		const struct fib_info *fi = fa->fa_info;
+		struct fib_info *fi = fa->fa_info;
 		__be32 mask = inet_make_mask(KEYLENGTH - fa->fa_slen);
 		unsigned int flags = fib_flag_trans(fa->fa_type, mask, fi);
 
@@ -2768,26 +2772,28 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
 
 		seq_setwidth(seq, 127);
 
-		if (fi)
+		if (fi) {
+			struct fib_nh *nh = fib_info_nh(fi, 0);
+
 			seq_printf(seq,
 				   "%s\t%08X\t%08X\t%04X\t%d\t%u\t"
 				   "%d\t%08X\t%d\t%u\t%u",
-				   fi->fib_dev ? fi->fib_dev->name : "*",
+				   nh->fib_nh_dev ? nh->fib_nh_dev->name : "*",
 				   prefix,
-				   fi->fib_nh->fib_nh_gw4, flags, 0, 0,
+				   nh->fib_nh_gw4, flags, 0, 0,
 				   fi->fib_priority,
 				   mask,
 				   (fi->fib_advmss ?
 				    fi->fib_advmss + 40 : 0),
 				   fi->fib_window,
 				   fi->fib_rtt >> 3);
-		else
+		} else {
 			seq_printf(seq,
 				   "*\t%08X\t%08X\t%04X\t%d\t%u\t"
 				   "%d\t%08X\t%d\t%u\t%u",
 				   prefix, 0, flags, 0, 0, 0,
 				   mask, 0, 0, 0);
-
+		}
 		seq_pad(seq, '\n');
 	}
 
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 11ddc276776e..05a6a8ecb574 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -99,6 +99,7 @@
 #include <net/inetpeer.h>
 #include <net/sock.h>
 #include <net/ip_fib.h>
+#include <net/nexthop.h>
 #include <net/arp.h>
 #include <net/tcp.h>
 #include <net/icmp.h>
@@ -1950,7 +1951,7 @@ static int ip_mkroute_input(struct sk_buff *skb,
 			    struct flow_keys *hkeys)
 {
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
-	if (res->fi && res->fi->fib_nhs > 1) {
+	if (res->fi && fib_info_num_path(res->fi) > 1) {
 		int h = fib_multipath_hash(res->fi->fib_net, NULL, skb, hkeys);
 
 		fib_select_multipath(res, h);