nexthop: Expand nexthop_is_multipath in a few places

I got too fancy consolidating checks on multipath type. The result
is that path lookups can access 2 different nh_grp structs as exposed
by Nik's torture tests. Expand nexthop_is_multipath within nexthop.h to
avoid multiple, nh_grp dereferences and make decisions based on the
consistent struct.

Only 2 places left using nexthop_is_multipath are within IPv6, both
only check that the nexthop is a multipath for a branching decision
which are acceptable.

Fixes: 430a049190de ("nexthop: Add support for nexthop groups")
Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index 8a34351..f09e8d7 100644 (file)
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -137,21 +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
         */
@@ -186,12 +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);
@@ -217,10 +218,15 @@ 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);
@@ -264,8 +270,11 @@ 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;
        }