linux-kernel - Re: [PATCH v2] tty: rocket: reduce stack usage

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Message-ID: <afe485c6-7816-96dd-f301-1c0797e8b7ce@suse.com>
Date:   Mon, 21 Oct 2019 07:59:55 +0200
From:   Jiri Slaby <jslaby@...e.com>
To:     Sudip Mukherjee <sudipm.mukherjee@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] tty: rocket: reduce stack usage

On 18. 10. 19, 18:17, Sudip Mukherjee wrote:
> The build of xtensa allmodconfig gives warning of:
> In function 'get_ports.isra.0':
> warning: the frame size of 1040 bytes is larger than 1024 bytes
> 
> Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>

Acked-by: Jiri Slaby <jslaby@...e.cz>

Thanks.

> v2: check faliure of kzalloc
> 
>  drivers/tty/rocket.c | 32 +++++++++++++++++++-------------
>  1 file changed, 19 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/tty/rocket.c b/drivers/tty/rocket.c
> index 5ba6816ebf81..fbaa4ec85560 100644
> --- a/drivers/tty/rocket.c
> +++ b/drivers/tty/rocket.c
> @@ -1222,22 +1222,28 @@ static int set_config(struct tty_struct *tty, struct r_port *info,
>   */
>  static int get_ports(struct r_port *info, struct rocket_ports __user *retports)
>  {
> -	struct rocket_ports tmp;
> -	int board;
> +	struct rocket_ports *tmp;
> +	int board, ret = 0;
>  
> -	memset(&tmp, 0, sizeof (tmp));
> -	tmp.tty_major = rocket_driver->major;
> +	tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);
> +	if (!tmp)
> +		return -ENOMEM;
> +
> +	tmp->tty_major = rocket_driver->major;
>  
>  	for (board = 0; board < 4; board++) {
> -		tmp.rocketModel[board].model = rocketModel[board].model;
> -		strcpy(tmp.rocketModel[board].modelString, rocketModel[board].modelString);
> -		tmp.rocketModel[board].numPorts = rocketModel[board].numPorts;
> -		tmp.rocketModel[board].loadrm2 = rocketModel[board].loadrm2;
> -		tmp.rocketModel[board].startingPortNumber = rocketModel[board].startingPortNumber;
> -	}
> -	if (copy_to_user(retports, &tmp, sizeof (*retports)))
> -		return -EFAULT;
> -	return 0;
> +		tmp->rocketModel[board].model = rocketModel[board].model;
> +		strcpy(tmp->rocketModel[board].modelString,
> +		       rocketModel[board].modelString);
> +		tmp->rocketModel[board].numPorts = rocketModel[board].numPorts;
> +		tmp->rocketModel[board].loadrm2 = rocketModel[board].loadrm2;
> +		tmp->rocketModel[board].startingPortNumber =
> +			rocketModel[board].startingPortNumber;
> +	}
> +	if (copy_to_user(retports, tmp, sizeof(*retports)))
> +		ret = -EFAULT;
> +	kfree(tmp);
> +	return ret;
>  }
>  
>  static int reset_rm2(struct r_port *info, void __user *arg)
> 


-- 
js
suse labs