linux-kernel - Re: [PATCH] net: x25: Optimize the code in {compat_}x25_subscr

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Date:   Thu, 01 Jul 2021 07:51:10 +0200
From:   Martin Schiller <ms@....tdt.de>
To:     Yajun Deng <yajun.deng@...ux.dev>
Cc:     davem@...emloft.net, kuba@...nel.org, linux-x25@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: x25: Optimize the code in
 {compat_}x25_subscr_ioctl()

On 2021-06-30 11:15, Yajun Deng wrote:
> Combine the redundant return values, make it more concise.
> 
> Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>
> ---
>  net/x25/af_x25.c   | 19 ++++++++-----------
>  net/x25/x25_link.c | 21 ++++++++++-----------
>  2 files changed, 18 insertions(+), 22 deletions(-)
> 
> diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
> index 3583354a7d7f..53c40fc7c1fd 100644
> --- a/net/x25/af_x25.c
> +++ b/net/x25/af_x25.c
> @@ -1625,21 +1625,19 @@ static int compat_x25_subscr_ioctl(unsigned int 
> cmd,
>  	struct net_device *dev;
>  	int rc = -EINVAL;
> 
> -	rc = -EFAULT;
> -	if (copy_from_user(&x25_subscr, x25_subscr32, sizeof(*x25_subscr32)))
> +	if (copy_from_user(&x25_subscr, x25_subscr32, sizeof(*x25_subscr32))) 
> {
> +		rc = -EFAULT;
>  		goto out;
> +	}
> 
> -	rc = -EINVAL;
>  	dev = x25_dev_get(x25_subscr.device);
> -	if (dev == NULL)
> +	if (!dev)
>  		goto out;
> 
>  	nb = x25_get_neigh(dev);
> -	if (nb == NULL)
> +	if (!nb)
>  		goto out_dev_put;
> 
> -	dev_put(dev);
> -
>  	if (cmd == SIOCX25GSUBSCRIP) {
>  		read_lock_bh(&x25_neigh_list_lock);
>  		x25_subscr.extended = nb->extended;
> @@ -1648,7 +1646,6 @@ static int compat_x25_subscr_ioctl(unsigned int 
> cmd,
>  		rc = copy_to_user(x25_subscr32, &x25_subscr,
>  				sizeof(*x25_subscr32)) ? -EFAULT : 0;
>  	} else {
> -		rc = -EINVAL;
>  		if (x25_subscr.extended == 0 || x25_subscr.extended == 1) {
>  			rc = 0;
>  			write_lock_bh(&x25_neigh_list_lock);
> @@ -1658,11 +1655,11 @@ static int compat_x25_subscr_ioctl(unsigned int 
> cmd,
>  		}
>  	}
>  	x25_neigh_put(nb);
> -out:
> -	return rc;
> +
>  out_dev_put:
>  	dev_put(dev);
> -	goto out;
> +out:
> +	return rc;
>  }
> 
>  static int compat_x25_ioctl(struct socket *sock, unsigned int cmd,
> diff --git a/net/x25/x25_link.c b/net/x25/x25_link.c
> index 5460b9146dd8..01a13ec88ce8 100644
> --- a/net/x25/x25_link.c
> +++ b/net/x25/x25_link.c
> @@ -360,19 +360,19 @@ int x25_subscr_ioctl(unsigned int cmd, void 
> __user *arg)
>  	if (cmd != SIOCX25GSUBSCRIP && cmd != SIOCX25SSUBSCRIP)
>  		goto out;
> 
> -	rc = -EFAULT;
> -	if (copy_from_user(&x25_subscr, arg, sizeof(x25_subscr)))
> +	if (copy_from_user(&x25_subscr, arg, sizeof(x25_subscr))) {
> +		rc = -EFAULT;
>  		goto out;
> +	}
> 
> -	rc = -EINVAL;
> -	if ((dev = x25_dev_get(x25_subscr.device)) == NULL)
> +	dev = x25_dev_get(x25_subscr.device);
> +	if (!dev)
>  		goto out;
> 
> -	if ((nb = x25_get_neigh(dev)) == NULL)
> +	nb = x25_get_neigh(dev);
> +	if (!nb)
>  		goto out_dev_put;
> 
> -	dev_put(dev);
> -
>  	if (cmd == SIOCX25GSUBSCRIP) {
>  		read_lock_bh(&x25_neigh_list_lock);
>  		x25_subscr.extended	     = nb->extended;
> @@ -381,7 +381,6 @@ int x25_subscr_ioctl(unsigned int cmd, void __user 
> *arg)
>  		rc = copy_to_user(arg, &x25_subscr,
>  				  sizeof(x25_subscr)) ? -EFAULT : 0;
>  	} else {
> -		rc = -EINVAL;
>  		if (!(x25_subscr.extended && x25_subscr.extended != 1)) {
>  			rc = 0;
>  			write_lock_bh(&x25_neigh_list_lock);
> @@ -391,11 +390,11 @@ int x25_subscr_ioctl(unsigned int cmd, void 
> __user *arg)
>  		}
>  	}
>  	x25_neigh_put(nb);
> -out:
> -	return rc;
> +
>  out_dev_put:
>  	dev_put(dev);
> -	goto out;
> +out:
> +	return rc;
>  }

Looks good to me.

Acked-by: Martin Schiller <ms@....tdt.de>