[PATCH net-next v2] net/mlx5e: Ensure macsec_rule is always initiailized in macsec_fs_{r,t}x_add_rule()

[Nathan Chancellor <nathan@kernel.org>]

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: e467b283ffd5 ("net/mlx5e: Add MACsec TX steering rules")
Fixes: 3b20949cb21b ("net/mlx5e: Add MACsec RX steering rules")
Link: https://github.com/ClangBuiltLinux/linux/issues/1706
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---

v1 -> v2: https://lore.kernel.org/20220908153207.4048871-1-nathan@kernel.org/

* Don't use a label and goto, just initialize it to NULL at the top of
  the functions (Raed).

Tom, I did not carry forward your reviewed-by tag, even though this is a
pretty obvious fix.

Blurb from v1:

I thought netdev was doing testing with clang so that new warnings do
not show up. Did something break or stop working since this is the
second time in two weeks that new warnings have appeared in -next?

 drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c
index 608fbbaa5a58..13dc628b988a 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec_fs.c
+++ b/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;

base-commit: 169ccf0e40825d9e465863e4707d8e8546d3c3cb
-- 
2.37.3