mlxsw: spectrum: Veto sampling if already enabled on port

The per-port sampling triggers (i.e., ingress / egress) cannot be
enabled twice. Meaning, the below configuration will not result in
packets being sampled twice:

 # tc filter add dev swp1 ingress matchall skip_sw action sample rate 100 group 1
 # tc filter add dev swp1 ingress matchall skip_sw action sample rate 100 group 1

Therefore, reject such configurations.

Fixes: 90f53c53ec4a ("mlxsw: spectrum: Start using sampling triggers hash table")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index efc7acb..bca0354 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -2668,6 +2668,11 @@ mlxsw_sp_sample_trigger_params_set(struct mlxsw_sp *mlxsw_sp,
                return mlxsw_sp_sample_trigger_node_init(mlxsw_sp, &key,
                                                         params);
 
+       if (trigger_node->trigger.local_port) {
+               NL_SET_ERR_MSG_MOD(extack, "Sampling already enabled on port");
+               return -EINVAL;
+       }
+
        if (trigger_node->params.psample_group != params->psample_group ||
            trigger_node->params.truncate != params->truncate ||
            trigger_node->params.rate != params->rate ||