[5.6,169/177] nexthop: Expand nexthop_is_multipath in a few places
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Message ID 20200601174102.208014594@linuxfoundation.org
State New
Headers show
Series
  • Untitled series #446659
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Commit Message

Greg KH June 1, 2020, 5:55 p.m. UTC
From: David Ahern <dsahern@gmail.com>

commit 0b5e2e39739e861fa5fc84ab27a35dbe62a15330 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/net/nexthop.h |   41 +++++++++++++++++++++++++----------------
 1 file changed, 25 insertions(+), 16 deletions(-)

Patch
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--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -137,21 +137,20 @@  static inline unsigned int nexthop_num_p
 {
 	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 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(st
 	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_fi
 {
 	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;
 	}