Re: [PATCH 06/11] sysctl: Add size to register_net_sysctl function

[Dan Carpenter]

The patchset doesn't include the actual interesting changes, just a
bunch of mechanical prep work.

On Wed, Jun 21, 2023 at 11:09:55AM +0200, Joel Granados wrote:
> diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
> index a91283d1e5bf..7b717434368c 100644
> --- a/net/ieee802154/6lowpan/reassembly.c
> +++ b/net/ieee802154/6lowpan/reassembly.c
> @@ -379,7 +379,8 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
>  	table[1].extra2	= &ieee802154_lowpan->fqdir->high_thresh;
>  	table[2].data	= &ieee802154_lowpan->fqdir->timeout;
>  
> -	hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
> +	hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table,
> +				  ARRAY_SIZE(lowpan_frags_ns_ctl_table));

For example, in lowpan_frags_ns_sysctl_register() the sentinel is
sometimes element zero if the user doesn't have enough permissions.  I
would want to ensure that was handled correctly, but that's going to be
done later in a completely different patchset.  I'm definitely not going
to remember to check.

> diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
> index dc5165d3eec4..6f96aae76537 100644
> --- a/net/mpls/af_mpls.c
> +++ b/net/mpls/af_mpls.c
> @@ -1395,6 +1395,40 @@ static const struct ctl_table mpls_dev_table[] = {
>  	{ }
>  };
>  
> +static int mpls_platform_labels(struct ctl_table *table, int write,
> +				void *buffer, size_t *lenp, loff_t *ppos);
> +#define MPLS_NS_SYSCTL_OFFSET(field)		\
> +	(&((struct net *)0)->field)
> +
> +static const struct ctl_table mpls_table[] = {
> +	{
> +		.procname	= "platform_labels",
> +		.data		= NULL,
> +		.maxlen		= sizeof(int),
> +		.mode		= 0644,
> +		.proc_handler	= mpls_platform_labels,
> +	},
> +	{
> +		.procname	= "ip_ttl_propagate",
> +		.data		= MPLS_NS_SYSCTL_OFFSET(mpls.ip_ttl_propagate),
> +		.maxlen		= sizeof(int),
> +		.mode		= 0644,
> +		.proc_handler	= proc_dointvec_minmax,
> +		.extra1		= SYSCTL_ZERO,
> +		.extra2		= SYSCTL_ONE,
> +	},
> +	{
> +		.procname	= "default_ttl",
> +		.data		= MPLS_NS_SYSCTL_OFFSET(mpls.default_ttl),
> +		.maxlen		= sizeof(int),
> +		.mode		= 0644,
> +		.proc_handler	= proc_dointvec_minmax,
> +		.extra1		= SYSCTL_ONE,
> +		.extra2		= &ttl_max,
> +	},
> +	{ }
> +};
> +
>  static int mpls_dev_sysctl_register(struct net_device *dev,
>  				    struct mpls_dev *mdev)
>  {
> @@ -1410,7 +1444,7 @@ static int mpls_dev_sysctl_register(struct net_device *dev,
>  	/* Table data contains only offsets relative to the base of
>  	 * the mdev at this point, so make them absolute.
>  	 */
> -	for (i = 0; i < ARRAY_SIZE(mpls_dev_table); i++) {
> +	for (i = 0; i < ARRAY_SIZE(mpls_dev_table) - 1; i++) {

Adding the " - 1" is just a gratuitous change.  It's not required.
It makes that patch more confusing to review.  And you're just going
to have to change it back to how it was if you remove the sentinel.

>  		table[i].data = (char *)mdev + (uintptr_t)table[i].data;
>  		table[i].extra1 = mdev;
>  		table[i].extra2 = net;
> @@ -1418,7 +1452,8 @@ static int mpls_dev_sysctl_register(struct net_device *dev,
>  
>  	snprintf(path, sizeof(path), "net/mpls/conf/%s", dev->name);
>  
> -	mdev->sysctl = register_net_sysctl(net, path, table);
> +	mdev->sysctl = register_net_sysctl(net, path, table,
> +					   ARRAY_SIZE(mpls_dev_table));
>  	if (!mdev->sysctl)
>  		goto free;
>  
> @@ -1432,6 +1467,7 @@ static int mpls_dev_sysctl_register(struct net_device *dev,
>  	return -ENOBUFS;
>  }
>  
> +

Double blank line.

>  static void mpls_dev_sysctl_unregister(struct net_device *dev,
>  				       struct mpls_dev *mdev)
>  {

regards,
dan carpenter