From: Ido Schimmel <idosch@mellanox.com>
Date: Sun, 19 Apr 2020 10:01:05 +0300
Subject: mlxsw: spectrum_router: Re-increase scale of IPv6 nexthop groups
Patch-mainline: v5.8-rc1
Git-commit: cec2500d44751a7782d16ce99fca104e77e324a5
References: bsc#1176774

As explained in commit fc25996e6f46 ("mlxsw: spectrum_router: Increase
scale of IPv6 nexthop groups"), each nexthop group is hashed by XOR-ing
the interface indexes of all the member nexthop devices.

To avoid many different nexthop groups ending up using the same key, the
above commit started hashing the interface indexes themselves before
they are XOR-ed.

However, in cases in which there are many nexthop groups that all use
the same nexthop device and only differ in the gateway IP, we can still
end up in a situation in which all the groups are using the same key.
This eventually leads to -EBUSY error from rhashtable during insertion.

Improve the situation by also making the gateway IP part of the key.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Alex Veber <alexve@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Tested-by: Alex Veber <alexve@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -2999,6 +2999,7 @@ static u32 mlxsw_sp_nexthop_group_hash_o
 		for (i = 0; i < nh_grp->count; i++) {
 			nh = &nh_grp->nexthops[i];
 			val ^= jhash(&nh->ifindex, sizeof(nh->ifindex), seed);
+			val ^= jhash(&nh->gw_addr, sizeof(nh->gw_addr), seed);
 		}
 		return jhash(&val, sizeof(val), seed);
 	default:
@@ -3012,11 +3013,14 @@ mlxsw_sp_nexthop6_group_hash(struct mlxs
 {
 	unsigned int val = fib6_entry->nrt6;
 	struct mlxsw_sp_rt6 *mlxsw_sp_rt6;
-	struct net_device *dev;
 
 	list_for_each_entry(mlxsw_sp_rt6, &fib6_entry->rt6_list, list) {
-		dev = mlxsw_sp_rt6->rt->fib6_nh->fib_nh_dev;
+		struct fib6_nh *fib6_nh = mlxsw_sp_rt6->rt->fib6_nh;
+		struct net_device *dev = fib6_nh->fib_nh_dev;
+		struct in6_addr *gw = &fib6_nh->fib_nh_gw6;
+
 		val ^= jhash(&dev->ifindex, sizeof(dev->ifindex), seed);
+		val ^= jhash(gw, sizeof(*gw), seed);
 	}
 
 	return jhash(&val, sizeof(val), seed);