[PATCH net 1/7] mlxsw: spectrum: Use different seeds for ECMP and LAG hash

[Ido Schimmel]

From: Ido Schimmel <ido...@mellanox.com>

The same hash function and seed are used for both ECMP and LAG hash.
Therefore, when a LAG device is used as a nexthop device as part of an
ECMP group, hash polarization can occur and all the traffic will be
hashed to a single LAG slave.

Fix this by using a different seed for the LAG hash.

Fixes: fa73989f2697 ("mlxsw: spectrum: Use a stable ECMP/LAG seed")
Signed-off-by: Ido Schimmel <ido...@mellanox.com>
Reported-by: Alex Veber <ale...@mellanox.com>
Tested-by: Alex Veber <ale...@mellanox.com>
Acked-by: Jiri Pirko <j...@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c 
b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index dfe6b44baf63..23204356ad88 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -4280,13 +4280,16 @@ static void mlxsw_sp_traps_fini(struct mlxsw_sp 
*mlxsw_sp)
        }
 }
 
+#define MLXSW_SP_LAG_SEED_INIT 0xcafecafe
+
 static int mlxsw_sp_lag_init(struct mlxsw_sp *mlxsw_sp)
 {
        char slcr_pl[MLXSW_REG_SLCR_LEN];
        u32 seed;
        int err;
 
-       seed = jhash(mlxsw_sp->base_mac, sizeof(mlxsw_sp->base_mac), 0);
+       seed = jhash(mlxsw_sp->base_mac, sizeof(mlxsw_sp->base_mac),
+                    MLXSW_SP_LAG_SEED_INIT);
        mlxsw_reg_slcr_pack(slcr_pl, MLXSW_REG_SLCR_LAG_HASH_SMAC |
                                     MLXSW_REG_SLCR_LAG_HASH_DMAC |
                                     MLXSW_REG_SLCR_LAG_HASH_ETHERTYPE |
-- 
2.20.1