Commit 0b5e2e39 authored by David Ahern's avatar David Ahern Committed by David S. Miller
Browse files

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: 430a0491 ("nexthop: Add support for nexthop groups")
Signed-off-by: default avatarDavid Ahern <dsahern@gmail.com>
Acked-by: default avatarNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 90f33bff

include/net/nexthop.h

+25 −16
Original line number Diff line number Diff line
@@ -137,10 +137,11 @@ 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);

		if (nh_grp->mpath)

			rc = nh_grp->num_nh;

	}
@@ -148,10 +149,8 @@ static inline unsigned int nexthop_num_path(const struct nexthop *nh) 
}



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);
@@ -217,11 +218,16 @@ 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->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;
@@ -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;

	}

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