Subject: Re: [RFC][PATCH -mm take4 6/6] add ioctls for adding/removing target

From: Andrew Morton <[email-masked]>
Date: Thu, 19 Apr 2007 21:16:30 -0700

On Wed, 18 Apr 2007 21:14:55 +0900 Keiichi KII <[email-masked]> wrote:

> From: Keiichi KII <[email-masked]>
> 
> We add ioctls for adding/removing target.
> If we use NETCONSOLE_ADD_TARGET ioctl, 
> we can dynamically add netconsole target.
> If we use NETCONSOLE_REMOVE_TARGET ioctl,
> we can dynamically remoe netconsole target.
> 
> ...
>
> --- mm.orig/drivers/net/netconsole.c
> +++ mm/drivers/net/netconsole.c
> @@ -47,6 +47,7 @@
>  #include <linux/netpoll.h>
>  #include <linux/miscdevice.h>
>  #include <linux/inet.h>
> +#include <linux/netconsole.h>
>  
>  MODULE_AUTHOR("Maintainer: Matt Mackall <[email-masked]>");
>  MODULE_DESCRIPTION("Console driver for network interfaces");
> @@ -313,6 +314,64 @@ static void release_target(struct kobjec
>  	remove_target(nt);
>  }
>  
> +static int netconsole_ioctl(struct inode *inode, struct file *file,
> +			    unsigned int cmd, unsigned long arg)
> +{
> +	int id, count;
> +	char config[256];
> +	char *cur;
> +	struct netconsole_request req;
> +	struct netconsole_target *nt, *tmp;
> +	void __user *argp = (void __user *)arg;
> +
> +	switch (cmd) {
> +	case NETCON_ADD_TARGET:
> +		printk(KERN_INFO "netconsole: cmd=NETCON_ADD_TARGET\n");
> +		if (copy_from_user(&req, argp, sizeof(req)))
> +			return -EFAULT;
> +		cur = config;
> +		count = sprintf(cur, "%d@", req.local_port);
> +		cur += count;
> +		if (req.local_ip)
> +			count = sprintf(cur, "%d.%d.%d.%d/",
> +					NIPQUAD(req.local_ip));
> +		else
> +			count = sprintf(cur, "/");
> +		cur += count;
> +		count = sprintf(cur, "%s,", req.netdev_name);
> +		cur += count;
> +		count = sprintf(cur, "%d@", req.remote_port);
> +		cur += count;
> +		count = sprintf(cur, "%d.%d.%d.%d/",
> +				NIPQUAD(req.remote_ip));
> +		cur += count;
> +		count = sprintf(cur, "%02x:%02x:%02x:%02x:%02x:%02x",
> +				req.remote_mac[0], req.remote_mac[1],
> +				req.remote_mac[2], req.remote_mac[3],
> +				req.remote_mac[4], req.remote_mac[5]);
> +		printk(KERN_INFO "count = %d config=[%s]\n", count, config);
> +		if (add_target(config))
> +			return -EINVAL;
> +		break;
> +	case NETCON_REMOVE_TARGET:
> +		printk(KERN_INFO "netconsole: cmd=NETCON_REMOVE_TARGET\n");
> +		if (copy_from_user(&id, argp, sizeof(int)))
> +			return -EFAULT;
> +		printk(KERN_INFO "netconsole: id=%d\n", id);
> +		list_for_each_entry_safe(nt, tmp, &target_list, list) {
> +			if (nt->id == id) {
> +				kobject_unregister(&nt->obj);
> +				break;
> +			}
> +		}
> +		break;
> +	default:
> +		return -ENOTTY;
> +	}
> +
> +	return 0;
> +}
> +
>  static struct sysfs_ops target_sysfs_ops = {
>  	.show = show_target_attr,
>  	.store = store_target_attr
> @@ -324,9 +383,14 @@ static struct kobj_type target_ktype = {
>  	.default_attrs = target_attrs,
>  };
>  
> +static struct file_operations miscdev_fops = {
> +	.ioctl = netconsole_ioctl,
> +};
> +
>  static struct miscdevice netconsole_miscdev = {
>  	.minor = MISC_DYNAMIC_MINOR,
>  	.name = "netconsole",
> +	.fops = &miscdev_fops,
>  };
>  
>  static struct notifier_block netconsole_notifier = {

We'll need to wake up the net guys to get an opinion here.  Using an
ioctl() against a miscdev is rather untypical for networking.  I'd expect
they'd prefer to see a netlink-based interface to userspace.