Re: [PATCH 09/39] wimax: provides user space with information needed when opening a WiMAX device

Johannes Berg
2008-11-27T09:54:11Z

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On Wed, 2008-11-26 at 15:07 -0800, Inaky Perez-Gonzalez wrote:
> When user space wants to open a handle to a WiMAX device, it needs
> information that is provided as a response to an "open" generic
> netlink message.

Why is this called "open" when it's not actually any opening that would
be bracketed with "close"? It seems more like "get info" to me?

> + result = -ENOMEM;
> + reply_skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
> + if (reply_skb == NULL)
> + goto error_new;
> + data = genlmsg_put_reply(reply_skb, genl_info,
> + &wimax_dev->gnl_family,
> + 0, WIMAX_GNL_RP_IFINFO);
> + if (data == NULL)
> + goto error_put_reply;
> +
> + nla_groups = nla_nest_start(reply_skb, WIMAX_GNL_IFINFO_MC_GROUPS);
> + if (nla_groups == NULL)
> + goto error_groups_start;
> +
> + list_for_each_entry(pipe_itr, &wimax_dev->pipe_list,
> + list_node) {
> + nla_group = nla_nest_start(reply_skb,
> + WIMAX_GNL_IFINFO_MC_GROUP);
> + if (nla_group == NULL)
> + goto error_group_start;
> +
> + nla_put_u16(reply_skb, WIMAX_GNL_IFINFO_MC_ID,
> + pipe_itr->mcg.id);
> + nla_put_string(reply_skb, WIMAX_GNL_IFINFO_MC_NAME,
> + pipe_itr->mcg.name);

All this is discoverable via the genl controller and a pipe naming
scheme, so I don't think you need this "open" command at all.

> + nla_nest_end(reply_skb, nla_group);
> + }
> + nla_nest_end(reply_skb, nla_groups);
> + genlmsg_end(reply_skb, data);
> +
> + result = genlmsg_reply(reply_skb, genl_info);
> + if (result < 0)
> + goto error_reply;
> + return 0;
> +
> +error_group_start:
> +error_groups_start:
> +error_reply:
> +error_put_reply:
> + nlmsg_free(reply_skb);
> +error_new:
> + return result;
> +}
> +
> +
> +static
> +int wimax_gnl_doit_open(struct sk_buff *skb, struct genl_info *info)
> +{
> + int result;
> + struct wimax_dev *wimax_dev;
> +
> + d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
> + result = -EPERM;
> + if (security_netlink_recv(skb, CAP_NET_ADMIN))
> + goto error_perm;

Ehm, you can do that check by adding the flag below...

> + result = -ENODEV;
> + wimax_dev = wimax_dev_get_by_genl_info(info);
> + if (wimax_dev == NULL)
> + goto error_no_wimax_dev;
> + mutex_lock(&wimax_dev->mutex);
> + result = wimax_dev_is_ready(wimax_dev);
> + if (result < 0)
> + goto error_not_ready;
> + result = __wimax_gnl_open_reply(wimax_dev, info);
> +error_not_ready:
> + mutex_unlock(&wimax_dev->mutex);
> + dev_put(wimax_dev->net_dev);
> +error_no_wimax_dev:
> +error_perm:
> + d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
> + return result;
> +}
> +
> +
> +struct genl_ops wimax_gnl_open = {
> + .cmd = WIMAX_GNL_OP_OPEN,
> + .flags = 0,

GENL_ADMIN_PERM and remove the checks above?

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