linux-kernel - Re: [PATCH v1 1/5] tty: rpmsg: Assign returned id to a local variable

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Date:   Tue, 2 Nov 2021 14:19:06 +0100
From:   Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        <linux-kernel@...r.kernel.org>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>
Subject: Re: [PATCH v1 1/5] tty: rpmsg: Assign returned id to a local variable

Hi Andy,

On 10/25/21 3:51 PM, Andy Shevchenko wrote:
> Instead of putting garbage in the data structure, assign allocated id
> or an error code to a temporary variable. This makes code cleaner.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/tty/rpmsg_tty.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/tty/rpmsg_tty.c b/drivers/tty/rpmsg_tty.c
> index 813076341ffd..8c17ddbf371d 100644
> --- a/drivers/tty/rpmsg_tty.c
> +++ b/drivers/tty/rpmsg_tty.c
> @@ -121,15 +121,16 @@ static struct rpmsg_tty_port *rpmsg_tty_alloc_cport(void)
>  		return ERR_PTR(-ENOMEM);
>  
>  	mutex_lock(&idr_lock);
> -	cport->id = idr_alloc(&tty_idr, cport, 0, MAX_TTY_RPMSG, GFP_KERNEL);
> +	err = idr_alloc(&tty_idr, cport, 0, MAX_TTY_RPMSG, GFP_KERNEL);
>  	mutex_unlock(&idr_lock);
>  
> -	if (cport->id < 0) {
> -		err = cport->id;
> +	if (err < 0) {
>  		kfree(cport);
>  		return ERR_PTR(err);
>  	}
>  
> +	cport->id = err;

Set the cport->id to the err variable on success doesn't seem completely clean
to me either.
What about renaming "err" by "id" as done in [1]?

[1]
https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/mps2-uart.c#L526

Regards,
Arnaud

> +
>  	return cport;
>  }
>  
>