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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Mon, 16 Mar 2020 13:55:55 -0700
Message-ID: <CAKwvOdkDUYYm9ZoTeKt-5kGhDTxo6w2XhOjONWhzh6M4rE5LpA@mail.gmail.com>
Subject: Re: [PATCH] mlx5: Remove uninitialized use of key in mlx5_core_create_mkey
To:     Nathan Chancellor <natechancellor@gmail.com>
Cc:     Saeed Mahameed <saeedm@mellanox.com>,
        Leon Romanovsky <leon@kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        linux-rdma@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>
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On Mon, Mar 16, 2020 at 1:35 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> Clang warns:
>
> ../drivers/net/ethernet/mellanox/mlx5/core/mr.c:63:21: warning: variable
> 'key' is uninitialized when used here [-Wuninitialized]
>                       mkey_index, key, mkey->key);
>                                   ^~~
> ../drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.h:54:6: note:
> expanded from macro 'mlx5_core_dbg'
>                  ##__VA_ARGS__)
>                    ^~~~~~~~~~~
> ../include/linux/dev_printk.h:114:39: note: expanded from macro
> 'dev_dbg'
>         dynamic_dev_dbg(dev, dev_fmt(fmt), ##__VA_ARGS__)
>                                              ^~~~~~~~~~~
> ../include/linux/dynamic_debug.h:158:19: note: expanded from macro
> 'dynamic_dev_dbg'
>                            dev, fmt, ##__VA_ARGS__)
>                                        ^~~~~~~~~~~
> ../include/linux/dynamic_debug.h:143:56: note: expanded from macro
> '_dynamic_func_call'
>         __dynamic_func_call(__UNIQUE_ID(ddebug), fmt, func, ##__VA_ARGS__)
>                                                               ^~~~~~~~~~~
> ../include/linux/dynamic_debug.h:125:15: note: expanded from macro
> '__dynamic_func_call'
>                 func(&id, ##__VA_ARGS__);               \
>                             ^~~~~~~~~~~
> ../drivers/net/ethernet/mellanox/mlx5/core/mr.c:47:8: note: initialize
> the variable 'key' to silence this warning
>         u8 key;
>               ^
>                = '\0'
> 1 warning generated.
>
> key's initialization was removed in commit fc6a9f86f08a ("{IB,net}/mlx5:
> Assign mkey variant in mlx5_ib only") but its use was not fully removed.
> Remove it now so that there is no more warning.
>
> Fixes: fc6a9f86f08a ("{IB,net}/mlx5: Assign mkey variant in mlx5_ib only")
> Link: https://github.com/ClangBuiltLinux/linux/issues/932
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

Thanks for the patch and analysis, looks good to me!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
>  drivers/net/ethernet/mellanox/mlx5/core/mr.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/mr.c b/drivers/net/ethernet/mellanox/mlx5/core/mr.c
> index fd3e6d217c3b..366f2cbfc6db 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/mr.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/mr.c
> @@ -44,7 +44,6 @@ int mlx5_core_create_mkey(struct mlx5_core_dev *dev,
>         u32 mkey_index;
>         void *mkc;
>         int err;
> -       u8 key;
>
>         MLX5_SET(create_mkey_in, in, opcode, MLX5_CMD_OP_CREATE_MKEY);
>
> @@ -59,8 +58,7 @@ int mlx5_core_create_mkey(struct mlx5_core_dev *dev,
>         mkey->key |= mlx5_idx_to_mkey(mkey_index);
>         mkey->pd = MLX5_GET(mkc, mkc, pd);
>
> -       mlx5_core_dbg(dev, "out 0x%x, key 0x%x, mkey 0x%x\n",
> -                     mkey_index, key, mkey->key);
> +       mlx5_core_dbg(dev, "out 0x%x, mkey 0x%x\n", mkey_index, mkey->key);
>         return 0;
>  }
>  EXPORT_SYMBOL(mlx5_core_create_mkey);
> --
> 2.26.0.rc1
>
> --

-- 
Thanks,
~Nick Desaulniers