linux/net/mac80211/ieee80211_rate.c
Johannes Berg d0709a6518 mac80211: RCU-ify STA info structure access
This makes access to the STA hash table/list use RCU to protect
against freeing of items. However, it's not a true RCU, the
copy step is missing: whenever somebody changes a STA item it
is simply updated. This is an existing race condition that is
now somewhat understandable.

This patch also fixes the race key freeing vs. STA destruction
by making sure that sta_info_destroy() is always called under
RTNL and frees the key.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-03-06 15:30:46 -05:00

250 lines
5.8 KiB
C

/*
* Copyright 2002-2005, Instant802 Networks, Inc.
* Copyright 2005-2006, Devicescape Software, Inc.
* Copyright (c) 2006 Jiri Benc <jbenc@suse.cz>
*
* 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.
*/
#include <linux/kernel.h>
#include <linux/rtnetlink.h>
#include "ieee80211_rate.h"
#include "ieee80211_i.h"
struct rate_control_alg {
struct list_head list;
struct rate_control_ops *ops;
};
static LIST_HEAD(rate_ctrl_algs);
static DEFINE_MUTEX(rate_ctrl_mutex);
static char *ieee80211_default_rc_algo = CONFIG_MAC80211_RC_DEFAULT;
module_param(ieee80211_default_rc_algo, charp, 0644);
MODULE_PARM_DESC(ieee80211_default_rc_algo,
"Default rate control algorithm for mac80211 to use");
int ieee80211_rate_control_register(struct rate_control_ops *ops)
{
struct rate_control_alg *alg;
if (!ops->name)
return -EINVAL;
mutex_lock(&rate_ctrl_mutex);
list_for_each_entry(alg, &rate_ctrl_algs, list) {
if (!strcmp(alg->ops->name, ops->name)) {
/* don't register an algorithm twice */
WARN_ON(1);
mutex_unlock(&rate_ctrl_mutex);
return -EALREADY;
}
}
alg = kzalloc(sizeof(*alg), GFP_KERNEL);
if (alg == NULL) {
mutex_unlock(&rate_ctrl_mutex);
return -ENOMEM;
}
alg->ops = ops;
list_add_tail(&alg->list, &rate_ctrl_algs);
mutex_unlock(&rate_ctrl_mutex);
return 0;
}
EXPORT_SYMBOL(ieee80211_rate_control_register);
void ieee80211_rate_control_unregister(struct rate_control_ops *ops)
{
struct rate_control_alg *alg;
mutex_lock(&rate_ctrl_mutex);
list_for_each_entry(alg, &rate_ctrl_algs, list) {
if (alg->ops == ops) {
list_del(&alg->list);
kfree(alg);
break;
}
}
mutex_unlock(&rate_ctrl_mutex);
}
EXPORT_SYMBOL(ieee80211_rate_control_unregister);
static struct rate_control_ops *
ieee80211_try_rate_control_ops_get(const char *name)
{
struct rate_control_alg *alg;
struct rate_control_ops *ops = NULL;
if (!name)
return NULL;
mutex_lock(&rate_ctrl_mutex);
list_for_each_entry(alg, &rate_ctrl_algs, list) {
if (!strcmp(alg->ops->name, name))
if (try_module_get(alg->ops->module)) {
ops = alg->ops;
break;
}
}
mutex_unlock(&rate_ctrl_mutex);
return ops;
}
/* Get the rate control algorithm. */
static struct rate_control_ops *
ieee80211_rate_control_ops_get(const char *name)
{
struct rate_control_ops *ops;
const char *alg_name;
if (!name)
alg_name = ieee80211_default_rc_algo;
else
alg_name = name;
ops = ieee80211_try_rate_control_ops_get(alg_name);
if (!ops) {
request_module("rc80211_%s", alg_name);
ops = ieee80211_try_rate_control_ops_get(alg_name);
}
if (!ops && name)
/* try default if specific alg requested but not found */
ops = ieee80211_try_rate_control_ops_get(ieee80211_default_rc_algo);
/* try built-in one if specific alg requested but not found */
if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
return ops;
}
static void ieee80211_rate_control_ops_put(struct rate_control_ops *ops)
{
module_put(ops->module);
}
struct rate_control_ref *rate_control_alloc(const char *name,
struct ieee80211_local *local)
{
struct rate_control_ref *ref;
ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
if (!ref)
goto fail_ref;
kref_init(&ref->kref);
ref->ops = ieee80211_rate_control_ops_get(name);
if (!ref->ops)
goto fail_ops;
ref->priv = ref->ops->alloc(local);
if (!ref->priv)
goto fail_priv;
return ref;
fail_priv:
ieee80211_rate_control_ops_put(ref->ops);
fail_ops:
kfree(ref);
fail_ref:
return NULL;
}
static void rate_control_release(struct kref *kref)
{
struct rate_control_ref *ctrl_ref;
ctrl_ref = container_of(kref, struct rate_control_ref, kref);
ctrl_ref->ops->free(ctrl_ref->priv);
ieee80211_rate_control_ops_put(ctrl_ref->ops);
kfree(ctrl_ref);
}
void rate_control_get_rate(struct net_device *dev,
struct ieee80211_supported_band *sband,
struct sk_buff *skb,
struct rate_selection *sel)
{
struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
struct rate_control_ref *ref = local->rate_ctrl;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct sta_info *sta;
int i;
rcu_read_lock();
sta = sta_info_get(local, hdr->addr1);
memset(sel, 0, sizeof(struct rate_selection));
ref->ops->get_rate(ref->priv, dev, sband, skb, sel);
/* Select a non-ERP backup rate. */
if (!sel->nonerp) {
for (i = 0; i < sband->n_bitrates; i++) {
struct ieee80211_rate *rate = &sband->bitrates[i];
if (sel->rate->bitrate < rate->bitrate)
break;
if (rate_supported(sta, sband->band, i) &&
!(rate->flags & IEEE80211_RATE_ERP_G))
sel->nonerp = rate;
}
}
rcu_read_unlock();
}
struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
{
kref_get(&ref->kref);
return ref;
}
void rate_control_put(struct rate_control_ref *ref)
{
kref_put(&ref->kref, rate_control_release);
}
int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
const char *name)
{
struct rate_control_ref *ref, *old;
ASSERT_RTNL();
if (local->open_count || netif_running(local->mdev))
return -EBUSY;
ref = rate_control_alloc(name, local);
if (!ref) {
printk(KERN_WARNING "%s: Failed to select rate control "
"algorithm\n", wiphy_name(local->hw.wiphy));
return -ENOENT;
}
old = local->rate_ctrl;
local->rate_ctrl = ref;
if (old) {
rate_control_put(old);
sta_info_flush(local, NULL);
}
printk(KERN_DEBUG "%s: Selected rate control "
"algorithm '%s'\n", wiphy_name(local->hw.wiphy),
ref->ops->name);
return 0;
}
void rate_control_deinitialize(struct ieee80211_local *local)
{
struct rate_control_ref *ref;
ref = local->rate_ctrl;
local->rate_ctrl = NULL;
rate_control_put(ref);
}