net/mlx5: fix GCC uninitialized variable warning

When building with -Db_sanitize=thread, GCC gives a warning:

drivers/net/mlx5/mlx5_flow_meter.c: In function ‘mlx5_flow_meter_create’:
drivers/net/mlx5/mlx5_flow_meter.c:1170:33: warning: ‘legacy_fm’ may be
    used uninitialized in this function [-Wmaybe-uninitialized]

This is a false-positive: legacy_fm is initialized and used
if and only if priv->sh->meter_aso_en is false.
Work around this by initializing legacy_fm to NULL.
Add an assertion before legacy_fm use in case the logic changes.

Fixes: 444320186393 ("net/mlx5: support meter creation with policy")
Cc: stable@dpdk.org
Reported-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>

diff --git a/drivers/net/mlx5/mlx5_flow_meter.c b/drivers/net/mlx5/mlx5_flow_meter.c
index 0e4e6ac3d5ab0c85711a72ec453483164e0406f0..0dc7fbfb3232073a5fbaeabb1401b2f038f242b0 100644 (file)
--- a/drivers/net/mlx5/mlx5_flow_meter.c
+++ b/drivers/net/mlx5/mlx5_flow_meter.c
@@ -1167,7 +1167,8 @@ mlx5_flow_meter_create(struct rte_eth_dev *dev, uint32_t meter_id,
        struct mlx5_legacy_flow_meters *fms = &priv->flow_meters;
        struct mlx5_flow_meter_profile *fmp;
        struct mlx5_flow_meter_info *fm;
-       struct mlx5_legacy_flow_meter *legacy_fm;
+       /* GCC fails to infer legacy_fm is set when !priv->sh->meter_aso_en. */
+       struct mlx5_legacy_flow_meter *legacy_fm = NULL;
        struct mlx5_flow_meter_policy *mtr_policy = NULL;
        struct mlx5_indexed_pool_config flow_ipool_cfg = {
                .size = 0,
@@ -1273,8 +1274,10 @@ mlx5_flow_meter_create(struct rte_eth_dev *dev, uint32_t meter_id,
        if (mlx5_flow_create_mtr_tbls(dev, fm, mtr_idx, domain_bitmap))
                goto error;
        /* Add to the flow meter list. */
-       if (!priv->sh->meter_aso_en)
+       if (!priv->sh->meter_aso_en) {
+               MLX5_ASSERT(legacy_fm != NULL);
                TAILQ_INSERT_TAIL(fms, legacy_fm, next);
+       }
        /* Add to the flow meter list. */
        fm->active_state = 1; /* Config meter starts as active. */
        fm->is_enable = 1;