Re: [PATCH net-next] net/mlx5e: Do not use err uninitialized in mlx5e_rep_add_meta_tunnel_rule()

Nick Desaulniers
2022-08-25T18:20:00Z

On Thu, Aug 25, 2022 at 11:06 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> Clang warns:
>
> drivers/net/ethernet/mellanox/mlx5/core/en_rep.c:481:6: error: variable 'err' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
> if (IS_ERR(flow_rule)) {
> ^~~~~~~~~~~~~~~~~
> drivers/net/ethernet/mellanox/mlx5/core/en_rep.c:489:9: note: uninitialized use occurs here
> return err;
> ^~~
> drivers/net/ethernet/mellanox/mlx5/core/en_rep.c:481:2: note: remove the 'if' if its condition is always true
> if (IS_ERR(flow_rule)) {
> ^~~~~~~~~~~~~~~~~~~~~~~
> drivers/net/ethernet/mellanox/mlx5/core/en_rep.c:474:9: note: initialize the variable 'err' to silence this warning
> int err;
> ^
> = 0
> 1 error generated.
>
> There is little reason to have the 'goto + error variable' construct in
> this function. Get rid of it and just return the PTR_ERR value in the if
> statement and 0 at the end.
>
> Fixes: 430e2d5e2a98 ("net/mlx5: E-Switch, Move send to vport meta rule creation")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1695
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Thanks for the fix!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
> drivers/net/ethernet/mellanox/mlx5/core/en_rep.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
> index c8617a62e542..a977804137a8 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
> @@ -471,22 +471,18 @@ mlx5e_rep_add_meta_tunnel_rule(struct mlx5e_priv *priv)
> struct mlx5_eswitch_rep *rep = rpriv->rep;
> struct mlx5_flow_handle *flow_rule;
> struct mlx5_flow_group *g;
> - int err;
>
> g = esw->fdb_table.offloads.send_to_vport_meta_grp;
> if (!g)
> return 0;
>
> flow_rule = mlx5_eswitch_add_send_to_vport_meta_rule(esw, rep->vport);
> - if (IS_ERR(flow_rule)) {
> - err = PTR_ERR(flow_rule);
> - goto out;
> - }
> + if (IS_ERR(flow_rule))
> + return PTR_ERR(flow_rule);
>
> rpriv->send_to_vport_meta_rule = flow_rule;
>
> -out:
> - return err;
> + return 0;
> }
>
> static void
>
> base-commit: c19d893fbf3f2f8fa864ae39652c7fee939edde2
> --
> 2.37.2
>

--
Thanks,
~Nick Desaulniers