5 files changed, 205 insertions, 79 deletions

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index b219a8fe0950..2ec062aaa978 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -447,6 +447,16 @@ static inline int fib_num_tclassid_users(struct net *net)
 #endif
 int fib_unmerge(struct net *net);
 
+static inline bool nhc_l3mdev_matches_dev(const struct fib_nh_common *nhc,
+const struct net_device *dev)
+{
+	if (nhc->nhc_dev == dev ||
+	    l3mdev_master_ifindex_rcu(nhc->nhc_dev) == dev->ifindex)
+		return true;
+
+	return false;
+}
+
 /* Exported by fib_semantics.c */
 int ip_fib_check_default(__be32 gw, struct net_device *dev);
 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force);
@@ -479,6 +489,8 @@ void fib_nh_common_release(struct fib_nh_common *nhc);
 void fib_alias_hw_flags_set(struct net *net, const struct fib_rt_info *fri);
 void fib_trie_init(void);
 struct fib_table *fib_trie_table(u32 id, struct fib_table *alias);
+bool fib_lookup_good_nhc(const struct fib_nh_common *nhc, int fib_flags,
+			 const struct flowi4 *flp);
 
 static inline void fib_combine_itag(u32 *itag, const struct fib_result *res)
 {
diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index c440ccc861fc..8c9f1a718859 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -70,6 +70,7 @@ struct nh_grp_entry {
 };
 
 struct nh_group {
+	struct nh_group		*spare; /* spare group for removals */
 	u16			num_nh;
 	bool			mpath;
 	bool			has_v4;
@@ -136,21 +137,20 @@ static inline unsigned int nexthop_num_path(const struct nexthop *nh)
 {
 	unsigned int rc = 1;
 
-	if (nexthop_is_multipath(nh)) {
+	if (nh->is_group) {
 		struct nh_group *nh_grp;
 
 		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
-		rc = nh_grp->num_nh;
+		if (nh_grp->mpath)
+			rc = nh_grp->num_nh;
 	}
 
 	return rc;
 }
 
 static inline
-struct nexthop *nexthop_mpath_select(const struct nexthop *nh, int nhsel)
+struct nexthop *nexthop_mpath_select(const struct nh_group *nhg, int nhsel)
 {
-	const struct nh_group *nhg = rcu_dereference_rtnl(nh->nh_grp);
-
 	/* for_nexthops macros in fib_semantics.c grabs a pointer to
 	 * the nexthop before checking nhsel
 	 */
@@ -185,12 +185,14 @@ static inline bool nexthop_is_blackhole(const struct nexthop *nh)
 {
 	const struct nh_info *nhi;
 
-	if (nexthop_is_multipath(nh)) {
-		if (nexthop_num_path(nh) > 1)
-			return false;
-		nh = nexthop_mpath_select(nh, 0);
-		if (!nh)
+	if (nh->is_group) {
+		struct nh_group *nh_grp;
+
+		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
+		if (nh_grp->num_nh > 1)
 			return false;
+
+		nh = nh_grp->nh_entries[0].nh;
 	}
 
 	nhi = rcu_dereference_rtnl(nh->nh_info);
@@ -216,16 +218,79 @@ struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel)
 	BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0);
 	BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0);
 
-	if (nexthop_is_multipath(nh)) {
-		nh = nexthop_mpath_select(nh, nhsel);
-		if (!nh)
-			return NULL;
+	if (nh->is_group) {
+		struct nh_group *nh_grp;
+
+		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
+		if (nh_grp->mpath) {
+			nh = nexthop_mpath_select(nh_grp, nhsel);
+			if (!nh)
+				return NULL;
+		}
 	}
 
 	nhi = rcu_dereference_rtnl(nh->nh_info);
 	return &nhi->fib_nhc;
 }
 
+/* called from fib_table_lookup with rcu_lock */
+static inline
+struct fib_nh_common *nexthop_get_nhc_lookup(const struct nexthop *nh,
+					     int fib_flags,
+					     const struct flowi4 *flp,
+					     int *nhsel)
+{
+	struct nh_info *nhi;
+
+	if (nh->is_group) {
+		struct nh_group *nhg = rcu_dereference(nh->nh_grp);
+		int i;
+
+		for (i = 0; i < nhg->num_nh; i++) {
+			struct nexthop *nhe = nhg->nh_entries[i].nh;
+
+			nhi = rcu_dereference(nhe->nh_info);
+			if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
+				*nhsel = i;
+				return &nhi->fib_nhc;
+			}
+		}
+	} else {
+		nhi = rcu_dereference(nh->nh_info);
+		if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
+			*nhsel = 0;
+			return &nhi->fib_nhc;
+		}
+	}
+
+	return NULL;
+}
+
+static inline bool nexthop_uses_dev(const struct nexthop *nh,
+				    const struct net_device *dev)
+{
+	struct nh_info *nhi;
+
+	if (nh->is_group) {
+		struct nh_group *nhg = rcu_dereference(nh->nh_grp);
+		int i;
+
+		for (i = 0; i < nhg->num_nh; i++) {
+			struct nexthop *nhe = nhg->nh_entries[i].nh;
+
+			nhi = rcu_dereference(nhe->nh_info);
+			if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
+				return true;
+		}
+	} else {
+		nhi = rcu_dereference(nh->nh_info);
+		if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
+			return true;
+	}
+
+	return false;
+}
+
 static inline unsigned int fib_info_num_path(const struct fib_info *fi)
 {
 	if (unlikely(fi->nh))
@@ -263,8 +328,11 @@ static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh)
 {
 	struct nh_info *nhi;
 
-	if (nexthop_is_multipath(nh)) {
-		nh = nexthop_mpath_select(nh, 0);
+	if (nh->is_group) {
+		struct nh_group *nh_grp;
+
+		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
+		nh = nexthop_mpath_select(nh_grp, 0);
 		if (!nh)
 			return NULL;
 	}
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 1bf9da3a75f9..41079490a118 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -309,17 +309,18 @@ bool fib_info_nh_uses_dev(struct fib_info *fi, const struct net_device *dev)
 {
 	bool dev_match = false;
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
-	int ret;
+	if (unlikely(fi->nh)) {
+		dev_match = nexthop_uses_dev(fi->nh, dev);
+	} else {
+		int ret;
 
-	for (ret = 0; ret < fib_info_num_path(fi); ret++) {
-		const struct fib_nh_common *nhc = fib_info_nhc(fi, ret);
+		for (ret = 0; ret < fib_info_num_path(fi); ret++) {
+			const struct fib_nh_common *nhc = fib_info_nhc(fi, ret);
 
-		if (nhc->nhc_dev == dev) {
-			dev_match = true;
-			break;
-		} else if (l3mdev_master_ifindex_rcu(nhc->nhc_dev) == dev->ifindex) {
-			dev_match = true;
-			break;
+			if (nhc_l3mdev_matches_dev(nhc, dev)) {
+				dev_match = true;
+				break;
+			}
 		}
 	}
 #else
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 4f334b425538..248f1c1959a6 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1371,6 +1371,26 @@ static inline t_key prefix_mismatch(t_key key, struct key_vector *n)
 	return (key ^ prefix) & (prefix | -prefix);
 }
 
+bool fib_lookup_good_nhc(const struct fib_nh_common *nhc, int fib_flags,
+			 const struct flowi4 *flp)
+{
+	if (nhc->nhc_flags & RTNH_F_DEAD)
+		return false;
+
+	if (ip_ignore_linkdown(nhc->nhc_dev) &&
+	    nhc->nhc_flags & RTNH_F_LINKDOWN &&
+	    !(fib_flags & FIB_LOOKUP_IGNORE_LINKSTATE))
+		return false;
+
+	if (!(flp->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF)) {
+		if (flp->flowi4_oif &&
+		    flp->flowi4_oif != nhc->nhc_oif)
+			return false;
+	}
+
+	return true;
+}
+
 /* should be called with rcu_read_lock */
 int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
 		     struct fib_result *res, int fib_flags)
@@ -1503,6 +1523,7 @@ found:
 	/* Step 3: Process the leaf, if that fails fall back to backtracing */
 	hlist_for_each_entry_rcu(fa, &n->leaf, fa_list) {
 		struct fib_info *fi = fa->fa_info;
+		struct fib_nh_common *nhc;
 		int nhsel, err;
 
 		if ((BITS_PER_LONG > KEYLENGTH) || (fa->fa_slen < KEYLENGTH)) {
@@ -1528,26 +1549,25 @@ out_reject:
 		if (fi->fib_flags & RTNH_F_DEAD)
 			continue;
 
-		if (unlikely(fi->nh && nexthop_is_blackhole(fi->nh))) {
-			err = fib_props[RTN_BLACKHOLE].error;
-			goto out_reject;
+		if (unlikely(fi->nh)) {
+			if (nexthop_is_blackhole(fi->nh)) {
+				err = fib_props[RTN_BLACKHOLE].error;
+				goto out_reject;
+			}
+
+			nhc = nexthop_get_nhc_lookup(fi->nh, fib_flags, flp,
+						     &nhsel);
+			if (nhc)
+				goto set_result;
+			goto miss;
 		}
 
 		for (nhsel = 0; nhsel < fib_info_num_path(fi); nhsel++) {
-			struct fib_nh_common *nhc = fib_info_nhc(fi, nhsel);
+			nhc = fib_info_nhc(fi, nhsel);
 
-			if (nhc->nhc_flags & RTNH_F_DEAD)
+			if (!fib_lookup_good_nhc(nhc, fib_flags, flp))
 				continue;
-			if (ip_ignore_linkdown(nhc->nhc_dev) &&
-			    nhc->nhc_flags & RTNH_F_LINKDOWN &&
-			    !(fib_flags & FIB_LOOKUP_IGNORE_LINKSTATE))
-				continue;
-			if (!(flp->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF)) {
-				if (flp->flowi4_oif &&
-				    flp->flowi4_oif != nhc->nhc_oif)
-					continue;
-			}
-
+set_result:
 			if (!(fib_flags & FIB_LOOKUP_NOREF))
 				refcount_inc(&fi->fib_clntref);
 
@@ -1568,6 +1588,7 @@ out_reject:
 			return err;
 		}
 	}
+miss:
 #ifdef CONFIG_IP_FIB_TRIE_STATS
 	this_cpu_inc(stats->semantic_match_miss);
 #endif
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 715e14475220..563f71bcb2d7 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -63,9 +63,16 @@ static void nexthop_free_mpath(struct nexthop *nh)
 	int i;
 
 	nhg = rcu_dereference_raw(nh->nh_grp);
-	for (i = 0; i < nhg->num_nh; ++i)
-		WARN_ON(nhg->nh_entries[i].nh);
+	for (i = 0; i < nhg->num_nh; ++i) {
+		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
+
+		WARN_ON(!list_empty(&nhge->nh_list));
+		nexthop_put(nhge->nh);
+	}
+
+	WARN_ON(nhg->spare == nhg);
 
+	kfree(nhg->spare);
 	kfree(nhg);
 }
 
@@ -694,41 +701,56 @@ static void nh_group_rebalance(struct nh_group *nhg)
 	}
 }
 
-static void remove_nh_grp_entry(struct nh_grp_entry *nhge,
-				struct nh_group *nhg,
+static void remove_nh_grp_entry(struct net *net, struct nh_grp_entry *nhge,
 				struct nl_info *nlinfo)
 {
+	struct nh_grp_entry *nhges, *new_nhges;
+	struct nexthop *nhp = nhge->nh_parent;
 	struct nexthop *nh = nhge->nh;
-	struct nh_grp_entry *nhges;
-	bool found = false;
-	int i;
+	struct nh_group *nhg, *newg;
+	int i, j;
 
 	WARN_ON(!nh);
 
-	nhges = nhg->nh_entries;
-	for (i = 0; i < nhg->num_nh; ++i) {
-		if (found) {
-			nhges[i-1].nh = nhges[i].nh;
-			nhges[i-1].weight = nhges[i].weight;
-			list_del(&nhges[i].nh_list);
-			list_add(&nhges[i-1].nh_list, &nhges[i-1].nh->grp_list);
-		} else if (nhg->nh_entries[i].nh == nh) {
-			found = true;
-		}
-	}
+	nhg = rtnl_dereference(nhp->nh_grp);
+	newg = nhg->spare;
 
-	if (WARN_ON(!found))
+	/* last entry, keep it visible and remove the parent */
+	if (nhg->num_nh == 1) {
+		remove_nexthop(net, nhp, nlinfo);
 		return;
+	}
+
+	newg->has_v4 = nhg->has_v4;
+	newg->mpath = nhg->mpath;
+	newg->num_nh = nhg->num_nh;
 
-	nhg->num_nh--;
-	nhg->nh_entries[nhg->num_nh].nh = NULL;
+	/* copy old entries to new except the one getting removed */
+	nhges = nhg->nh_entries;
+	new_nhges = newg->nh_entries;
+	for (i = 0, j = 0; i < nhg->num_nh; ++i) {
+		/* current nexthop getting removed */
+		if (nhg->nh_entries[i].nh == nh) {
+			newg->num_nh--;
+			continue;
+		}
 
-	nh_group_rebalance(nhg);
+		list_del(&nhges[i].nh_list);
+		new_nhges[j].nh_parent = nhges[i].nh_parent;
+		new_nhges[j].nh = nhges[i].nh;
+		new_nhges[j].weight = nhges[i].weight;
+		list_add(&new_nhges[j].nh_list, &new_nhges[j].nh->grp_list);
+		j++;
+	}
 
-	nexthop_put(nh);
+	nh_group_rebalance(newg);
+	rcu_assign_pointer(nhp->nh_grp, newg);
+
+	list_del(&nhge->nh_list);
+	nexthop_put(nhge->nh);
 
 	if (nlinfo)
-		nexthop_notify(RTM_NEWNEXTHOP, nhge->nh_parent, nlinfo);
+		nexthop_notify(RTM_NEWNEXTHOP, nhp, nlinfo);
 }
 
 static void remove_nexthop_from_groups(struct net *net, struct nexthop *nh,
@@ -736,17 +758,11 @@ static void remove_nexthop_from_groups(struct net *net, struct nexthop *nh,
 {
 	struct nh_grp_entry *nhge, *tmp;
 
-	list_for_each_entry_safe(nhge, tmp, &nh->grp_list, nh_list) {
-		struct nh_group *nhg;
-
-		list_del(&nhge->nh_list);
-		nhg = rtnl_dereference(nhge->nh_parent->nh_grp);
-		remove_nh_grp_entry(nhge, nhg, nlinfo);
+	list_for_each_entry_safe(nhge, tmp, &nh->grp_list, nh_list)
+		remove_nh_grp_entry(net, nhge, nlinfo);
 
-		/* if this group has no more entries then remove it */
-		if (!nhg->num_nh)
-			remove_nexthop(net, nhge->nh_parent, nlinfo);
-	}
+	/* make sure all see the newly published array before releasing rtnl */
+	synchronize_rcu();
 }
 
 static void remove_nexthop_group(struct nexthop *nh, struct nl_info *nlinfo)
@@ -760,10 +776,7 @@ static void remove_nexthop_group(struct nexthop *nh, struct nl_info *nlinfo)
 		if (WARN_ON(!nhge->nh))
 			continue;
 
-		list_del(&nhge->nh_list);
-		nexthop_put(nhge->nh);
-		nhge->nh = NULL;
-		nhg->num_nh--;
+		list_del_init(&nhge->nh_list);
 	}
 }
 
@@ -1086,6 +1099,7 @@ static struct nexthop *nexthop_create_group(struct net *net,
 {
 	struct nlattr *grps_attr = cfg->nh_grp;
 	struct nexthop_grp *entry = nla_data(grps_attr);
+	u16 num_nh = nla_len(grps_attr) / sizeof(*entry);
 	struct nh_group *nhg;
 	struct nexthop *nh;
 	int i;
@@ -1096,12 +1110,21 @@ static struct nexthop *nexthop_create_group(struct net *net,
 
 	nh->is_group = 1;
 
-	nhg = nexthop_grp_alloc(nla_len(grps_attr) / sizeof(*entry));
+	nhg = nexthop_grp_alloc(num_nh);
 	if (!nhg) {
 		kfree(nh);
 		return ERR_PTR(-ENOMEM);
 	}
 
+	/* spare group used for removals */
+	nhg->spare = nexthop_grp_alloc(num_nh);
+	if (!nhg) {
+		kfree(nhg);
+		kfree(nh);
+		return NULL;
+	}
+	nhg->spare->spare = nhg;
+
 	for (i = 0; i < nhg->num_nh; ++i) {
 		struct nexthop *nhe;
 		struct nh_info *nhi;
@@ -1133,6 +1156,7 @@ out_no_nh:
 	for (; i >= 0; --i)
 		nexthop_put(nhg->nh_entries[i].nh);
 
+	kfree(nhg->spare);
 	kfree(nhg);
 	kfree(nh);