linux-kernel - Re: [PATCH] usb: core: Remove redundant NULL checks before kfree

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Date:   Fri, 10 Jun 2022 11:06:12 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     cgel.zte@...il.com
Cc:     oneukum@...e.com, olebowle@....com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, Minghao Chi <chi.minghao@....com.cn>,
        Zeal Robot <zealci@....com.cn>
Subject: Re: [PATCH] usb: core: Remove redundant NULL checks before kfree

On Mon, Jun 06, 2022 at 01:43:52AM +0000, cgel.zte@...il.com wrote:
> From: Minghao Chi <chi.minghao@....com.cn>
> 
> Checking a pointer for NULL before calling kfree() on it is redundant,
> kfree() deals with NULL pointers just fine.
> 
> Reported-by: Zeal Robot <zealci@....com.cn>
> Signed-off-by: Minghao Chi <chi.minghao@....com.cn>
> ---
>  drivers/usb/core/quirks.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
> index f99a65a64588..7e918e4a95f2 100644
> --- a/drivers/usb/core/quirks.c
> +++ b/drivers/usb/core/quirks.c
> @@ -56,10 +56,8 @@ static int quirks_param_set(const char *value, const struct kernel_param *kp)
>  		if (val[i] == ',')
>  			quirk_count++;
>  
> -	if (quirk_list) {
> -		kfree(quirk_list);
> -		quirk_list = NULL;
> -	}
> +	kfree(quirk_list);
> +	quirk_list = NULL;

Why are you setting this to NULL right before you assign it again:

>  	quirk_list = kcalloc(quirk_count, sizeof(struct quirk_entry),
>  			     GFP_KERNEL);

Please just free and move on.

thanks,

greg k-h