linux-kernel - Re: [PATCH] hwrng: optee: Initialize some structs using memset instead of braces

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Message-ID: <CAFA6WYNS3JckLR3=EzhbbO9G-emjXnQTGAzY2j8QoAJsteamSg@mail.gmail.com>
Date:   Tue, 19 Feb 2019 10:39:04 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     Jens Wiklander <jens.wiklander@...aro.org>,
        Matt Mackall <mpm@...enic.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Daniel Thompson <daniel.thompson@...aro.org>
Subject: Re: [PATCH] hwrng: optee: Initialize some structs using memset
 instead of braces

On Tue, 19 Feb 2019 at 08:52, Nathan Chancellor
<natechancellor@...il.com> wrote:
>
> Clang warns:
>
> drivers/char/hw_random/optee-rng.c:80:31: warning: suggest braces around
> initialization of subobject [-Wmissing-braces]
>         struct tee_param param[4] = {0};
>                                      ^
>                                      {}
> drivers/char/hw_random/optee-rng.c:177:31: warning: suggest braces
> around initialization of subobject [-Wmissing-braces]
>         struct tee_param param[4] = {0};
>                                      ^
>                                      {}
> drivers/char/hw_random/optee-rng.c:212:48: warning: suggest braces
> around initialization of subobject [-Wmissing-braces]
>         struct tee_ioctl_open_session_arg sess_arg = {0};
>                                                       ^
>                                                       {}
> 3 warnings generated.
>
> One way to fix these warnings is to add additional braces like Clang
> suggests; however, there has been a bit of push back from some
> maintainers, who just prefer memset as it is unambiguous, doesn't
> depend on a particular compiler version, and properly initializes all
> subobjects [1][2]. Do that here so there are no more warnings.
>
> [1]: https://lore.kernel.org/lkml/022e41c0-8465-dc7a-a45c-64187ecd9684@amd.com/
> [2]: https://lore.kernel.org/lkml/20181128.215241.702406654469517539.davem@davemloft.net/
>
> Fixes: 5fe8b1cc6a03 ("hwrng: add OP-TEE based rng driver")
> Link: https://github.com/ClangBuiltLinux/linux/issues/369
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>

Reviewed-by: Sumit Garg <sumit.garg@...aro.org>

> ---
>  drivers/char/hw_random/optee-rng.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/char/hw_random/optee-rng.c b/drivers/char/hw_random/optee-rng.c
> index 2b9fc8ac5500..46f4bcd28c41 100644
> --- a/drivers/char/hw_random/optee-rng.c
> +++ b/drivers/char/hw_random/optee-rng.c
> @@ -76,8 +76,11 @@ static size_t get_optee_rng_data(struct optee_rng_private *pvt_data,
>         u32 ret = 0;
>         u8 *rng_data = NULL;
>         size_t rng_size = 0;
> -       struct tee_ioctl_invoke_arg inv_arg = {0};
> -       struct tee_param param[4] = {0};
> +       struct tee_ioctl_invoke_arg inv_arg;
> +       struct tee_param param[4];
> +
> +       memset(&inv_arg, 0, sizeof(inv_arg));
> +       memset(&param, 0, sizeof(param));
>
>         /* Invoke TA_CMD_GET_ENTROPY function of Trusted App */
>         inv_arg.func = TA_CMD_GET_ENTROPY;
> @@ -173,8 +176,11 @@ static struct optee_rng_private pvt_data = {
>  static int get_optee_rng_info(struct device *dev)
>  {
>         u32 ret = 0;
> -       struct tee_ioctl_invoke_arg inv_arg = {0};
> -       struct tee_param param[4] = {0};
> +       struct tee_ioctl_invoke_arg inv_arg;
> +       struct tee_param param[4];
> +
> +       memset(&inv_arg, 0, sizeof(inv_arg));
> +       memset(&param, 0, sizeof(param));
>
>         /* Invoke TA_CMD_GET_RNG_INFO function of Trusted App */
>         inv_arg.func = TA_CMD_GET_RNG_INFO;
> @@ -209,7 +215,9 @@ static int optee_rng_probe(struct device *dev)
>  {
>         struct tee_client_device *rng_device = to_tee_client_device(dev);
>         int ret = 0, err = -ENODEV;
> -       struct tee_ioctl_open_session_arg sess_arg = {0};
> +       struct tee_ioctl_open_session_arg sess_arg;
> +
> +       memset(&sess_arg, 0, sizeof(sess_arg));
>
>         /* Open context with TEE driver */
>         pvt_data.ctx = tee_client_open_context(NULL, optee_ctx_match, NULL,
> --
> 2.21.0.rc1
>