linux-kernel - Re: [PATCH v2 3/3] clk: intel: Avoid unnecessary memset by improving code

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Message-ID: <159558097978.3847286.7904651694237654748@swboyd.mtv.corp.google.com>
Date:   Fri, 24 Jul 2020 01:56:19 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Rahul Tanwar <rahul.tanwar@...ux.intel.com>,
        linux-clk@...r.kernel.org, mturquette@...libre.com
Cc:     linux-kernel@...r.kernel.org, andriy.shevchenko@...el.com,
        qi-ming.wu@...el.com, yixin.zhu@...ux.intel.com,
        cheol.yong.kim@...el.com, rahul.tanwar.linux@...il.com,
        Rahul Tanwar <rahul.tanwar@...ux.intel.com>
Subject: Re: [PATCH v2 3/3] clk: intel: Avoid unnecessary memset by improving code

Quoting Rahul Tanwar (2020-07-15 23:30:32)
> memset can be avoided in a loop if the variables used are declared
> inside the loop. Move such variables declaration inside the loop
> to avoid memset.
> 
> Signed-off-by: Rahul Tanwar <rahul.tanwar@...ux.intel.com>
> ---
>  drivers/clk/x86/clk-cgu.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clk/x86/clk-cgu.c b/drivers/clk/x86/clk-cgu.c
> index c379fedfb9f2..9a1be7035fd0 100644
> --- a/drivers/clk/x86/clk-cgu.c
> +++ b/drivers/clk/x86/clk-cgu.c
> @@ -581,19 +581,18 @@ int lgm_clk_register_ddiv(struct lgm_clk_provider *ctx,
>                           unsigned int nr_clk)
>  {
>         struct device *dev = ctx->dev;
> -       struct clk_init_data init = {};
> -       struct lgm_clk_ddiv *ddiv;
>         struct clk_hw *hw;
>         unsigned int idx;
>         int ret;
>  
>         for (idx = 0; idx < nr_clk; idx++, list++) {
> -               ddiv = NULL;
> +               struct clk_init_data init = {};
> +               struct lgm_clk_ddiv *ddiv = NULL;

Assigning to NULL isn't necessary...

> +
>                 ddiv = devm_kzalloc(dev, sizeof(*ddiv), GFP_KERNEL);

because it's assigned right here. I'll just fix it.

>                 if (!ddiv)
>                         return -ENOMEM;
>  
> -               memset(&init, 0, sizeof(init));
>                 init.name = list->name;
>                 init.ops = &lgm_clk_ddiv_ops;
>                 init.flags = list->flags;