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id-table.c
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id-table.c
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/*
* Linux WiMAX
* Mappping of generic netlink family IDs to net devices
*
*
* Copyright (C) 2005-2006 Intel Corporation <[email protected]>
* Inaky Perez-Gonzalez <[email protected]>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
*
* We assign a single generic netlink family ID to each device (to
* simplify lookup).
*
* We need a way to map family ID to a wimax_dev pointer.
*
* The idea is to use a very simple lookup. Using a netlink attribute
* with (for example) the interface name implies a heavier search over
* all the network devices; seemed kind of a waste given that we know
* we are looking for a WiMAX device and that most systems will have
* just a single WiMAX adapter.
*
* We put all the WiMAX devices in the system in a linked list and
* match the generic link family ID against the list.
*
* By using a linked list, the case of a single adapter in the system
* becomes (almost) no overhead, while still working for many more. If
* it ever goes beyond two, I'll be surprised.
*/
#include <linux/device.h>
#include <net/genetlink.h>
#include <linux/netdevice.h>
#include <linux/list.h>
#include <linux/wimax.h>
#include "wimax-internal.h"
#define D_SUBMODULE id_table
#include "debug-levels.h"
static DEFINE_SPINLOCK(wimax_id_table_lock);
static struct list_head wimax_id_table = LIST_HEAD_INIT(wimax_id_table);
/*
* wimax_id_table_add - add a gennetlink familiy ID / wimax_dev mapping
*
* @wimax_dev: WiMAX device descriptor to associate to the Generic
* Netlink family ID.
*
* Look for an empty spot in the ID table; if none found, double the
* table's size and get the first spot.
*/
void wimax_id_table_add(struct wimax_dev *wimax_dev)
{
d_fnstart(3, NULL, "(wimax_dev %p)\n", wimax_dev);
spin_lock(&wimax_id_table_lock);
list_add(&wimax_dev->id_table_node, &wimax_id_table);
spin_unlock(&wimax_id_table_lock);
d_fnend(3, NULL, "(wimax_dev %p)\n", wimax_dev);
}
/*
* wimax_get_netdev_by_info - lookup a wimax_dev from the gennetlink info
*
* The generic netlink family ID has been filled out in the
* nlmsghdr->nlmsg_type field, so we pull it from there, look it up in
* the mapping table and reference the wimax_dev.
*
* When done, the reference should be dropped with
* 'dev_put(wimax_dev->net_dev)'.
*/
struct wimax_dev *wimax_dev_get_by_genl_info(
struct genl_info *info, int ifindex)
{
struct wimax_dev *wimax_dev = NULL;
d_fnstart(3, NULL, "(info %p ifindex %d)\n", info, ifindex);
spin_lock(&wimax_id_table_lock);
list_for_each_entry(wimax_dev, &wimax_id_table, id_table_node) {
if (wimax_dev->net_dev->ifindex == ifindex) {
dev_hold(wimax_dev->net_dev);
goto found;
}
}
wimax_dev = NULL;
d_printf(1, NULL, "wimax: no devices found with ifindex %d\n",
ifindex);
found:
spin_unlock(&wimax_id_table_lock);
d_fnend(3, NULL, "(info %p ifindex %d) = %p\n",
info, ifindex, wimax_dev);
return wimax_dev;
}
/*
* wimax_id_table_rm - Remove a gennetlink familiy ID / wimax_dev mapping
*
* @id: family ID to remove from the table
*/
void wimax_id_table_rm(struct wimax_dev *wimax_dev)
{
spin_lock(&wimax_id_table_lock);
list_del_init(&wimax_dev->id_table_node);
spin_unlock(&wimax_id_table_lock);
}
/*
* Release the gennetlink family id / mapping table
*
* On debug, verify that the table is empty upon removal. We want the
* code always compiled, to ensure it doesn't bit rot. It will be
* compiled out if CONFIG_BUG is disabled.
*/
void wimax_id_table_release(void)
{
struct wimax_dev *wimax_dev;
#ifndef CONFIG_BUG
return;
#endif
spin_lock(&wimax_id_table_lock);
list_for_each_entry(wimax_dev, &wimax_id_table, id_table_node) {
printk(KERN_ERR "BUG: %s wimax_dev %p ifindex %d not cleared\n",
__func__, wimax_dev, wimax_dev->net_dev->ifindex);
WARN_ON(1);
}
spin_unlock(&wimax_id_table_lock);
}