diff options
Diffstat (limited to 'drivers/staging/wimax/id-table.c')
| -rw-r--r-- | drivers/staging/wimax/id-table.c | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/drivers/staging/wimax/id-table.c b/drivers/staging/wimax/id-table.c new file mode 100644 index 000000000000..0e6f4aa87bc9 --- /dev/null +++ b/drivers/staging/wimax/id-table.c @@ -0,0 +1,130 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Linux WiMAX + * Mappping of generic netlink family IDs to net devices + * + * Copyright (C) 2005-2006 Intel Corporation <linux-wimax@intel.com> + * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com> + * + * 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) { + pr_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); +} |