net/mlx5e: Ensure macsec_rule is always initiailized in macsec_fs_{r,t}x_add_rule()

Clang warns:

  drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c:539:6: error: variable 'macsec_rule' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
          if (err)
              ^~~
  drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c:598:9: note: uninitialized use occurs here
          return macsec_rule;
                ^~~~~~~~~~~
  drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c:539:2: note: remove the 'if' if its condition is always false
          if (err)
          ^~~~~~~~
  drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c:523:38: note: initialize the variable 'macsec_rule' to silence this warning
          union mlx5e_macsec_rule *macsec_rule;
                                              ^
                                              = NULL
  drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c:1131:6: error: variable 'macsec_rule' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
          if (err)
              ^~~
  drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c:1215:9: note: uninitialized use occurs here
          return macsec_rule;
                ^~~~~~~~~~~
  drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c:1131:2: note: remove the 'if' if its condition is always false
          if (err)
          ^~~~~~~~
  drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c:1118:38: note: initialize the variable 'macsec_rule' to silence this warning
          union mlx5e_macsec_rule *macsec_rule;
                                              ^
                                              = NULL
  2 errors generated.

If macsec_fs_{r,t}x_ft_get() fail, macsec_rule will be uninitialized.
Initialize it to NULL at the top of each function so that it cannot be
used uninitialized.

Fixes: e467b283 ("net/mlx5e: Add MACsec TX steering rules")
Fixes: 3b20949c ("net/mlx5e: Add MACsec RX steering rules")
Link: https://github.com/ClangBuiltLinux/linux/issues/1706Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Raed Salem <raeds@nvidia.com>
Link: https://lore.kernel.org/r/20220911085748.461033-1-nathan@kernel.orgSigned-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c

@@ -518,9 +518,9 @@ macsec_fs_tx_add_rule(struct mlx5e_macsec_fs *macsec_fs,
 	struct mlx5_pkt_reformat_params reformat_params = {};
 	struct mlx5e_macsec_tx *tx_fs = macsec_fs->tx_fs;
 	struct net_device *netdev = macsec_fs->netdev;
+	union mlx5e_macsec_rule *macsec_rule = NULL;
 	struct mlx5_flow_destination dest = {};
 	struct mlx5e_macsec_tables *tx_tables;
-	union mlx5e_macsec_rule *macsec_rule;
 	struct mlx5e_macsec_tx_rule *tx_rule;
 	struct mlx5_flow_act flow_act = {};
 	struct mlx5_flow_handle *rule;
@@ -1112,10 +1112,10 @@ macsec_fs_rx_add_rule(struct mlx5e_macsec_fs *macsec_fs,
 	u8 action[MLX5_UN_SZ_BYTES(set_add_copy_action_in_auto)] = {};
 	struct mlx5e_macsec_rx *rx_fs = macsec_fs->rx_fs;
 	struct net_device *netdev = macsec_fs->netdev;
+	union mlx5e_macsec_rule *macsec_rule = NULL;
 	struct mlx5_modify_hdr *modify_hdr = NULL;
 	struct mlx5_flow_destination dest = {};
 	struct mlx5e_macsec_tables *rx_tables;
-	union mlx5e_macsec_rule *macsec_rule;
 	struct mlx5e_macsec_rx_rule *rx_rule;
 	struct mlx5_flow_act flow_act = {};
 	struct mlx5e_flow_table *ft_crypto;