rate.c revision a02cec2155fbea457eca8881870fd2de1a4c4c76 
1/*
2 * Copyright 2002-2005, Instant802 Networks, Inc.
3 * Copyright 2005-2006, Devicescape Software, Inc.
4 * Copyright (c) 2006 Jiri Benc <jbenc@suse.cz>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/kernel.h>
12#include <linux/rtnetlink.h>
13#include <linux/slab.h>
14#include "rate.h"
15#include "ieee80211_i.h"
16#include "debugfs.h"
17
18struct rate_control_alg {
19	struct list_head list;
20	struct rate_control_ops *ops;
21};
22
23static LIST_HEAD(rate_ctrl_algs);
24static DEFINE_MUTEX(rate_ctrl_mutex);
25
26static char *ieee80211_default_rc_algo = CONFIG_MAC80211_RC_DEFAULT;
27module_param(ieee80211_default_rc_algo, charp, 0644);
28MODULE_PARM_DESC(ieee80211_default_rc_algo,
29		 "Default rate control algorithm for mac80211 to use");
30
31int ieee80211_rate_control_register(struct rate_control_ops *ops)
32{
33	struct rate_control_alg *alg;
34
35	if (!ops->name)
36		return -EINVAL;
37
38	mutex_lock(&rate_ctrl_mutex);
39	list_for_each_entry(alg, &rate_ctrl_algs, list) {
40		if (!strcmp(alg->ops->name, ops->name)) {
41			/* don't register an algorithm twice */
42			WARN_ON(1);
43			mutex_unlock(&rate_ctrl_mutex);
44			return -EALREADY;
45		}
46	}
47
48	alg = kzalloc(sizeof(*alg), GFP_KERNEL);
49	if (alg == NULL) {
50		mutex_unlock(&rate_ctrl_mutex);
51		return -ENOMEM;
52	}
53	alg->ops = ops;
54
55	list_add_tail(&alg->list, &rate_ctrl_algs);
56	mutex_unlock(&rate_ctrl_mutex);
57
58	return 0;
59}
60EXPORT_SYMBOL(ieee80211_rate_control_register);
61
62void ieee80211_rate_control_unregister(struct rate_control_ops *ops)
63{
64	struct rate_control_alg *alg;
65
66	mutex_lock(&rate_ctrl_mutex);
67	list_for_each_entry(alg, &rate_ctrl_algs, list) {
68		if (alg->ops == ops) {
69			list_del(&alg->list);
70			kfree(alg);
71			break;
72		}
73	}
74	mutex_unlock(&rate_ctrl_mutex);
75}
76EXPORT_SYMBOL(ieee80211_rate_control_unregister);
77
78static struct rate_control_ops *
79ieee80211_try_rate_control_ops_get(const char *name)
80{
81	struct rate_control_alg *alg;
82	struct rate_control_ops *ops = NULL;
83
84	if (!name)
85		return NULL;
86
87	mutex_lock(&rate_ctrl_mutex);
88	list_for_each_entry(alg, &rate_ctrl_algs, list) {
89		if (!strcmp(alg->ops->name, name))
90			if (try_module_get(alg->ops->module)) {
91				ops = alg->ops;
92				break;
93			}
94	}
95	mutex_unlock(&rate_ctrl_mutex);
96	return ops;
97}
98
99/* Get the rate control algorithm. */
100static struct rate_control_ops *
101ieee80211_rate_control_ops_get(const char *name)
102{
103	struct rate_control_ops *ops;
104	const char *alg_name;
105
106	kparam_block_sysfs_write(ieee80211_default_rc_algo);
107	if (!name)
108		alg_name = ieee80211_default_rc_algo;
109	else
110		alg_name = name;
111
112	ops = ieee80211_try_rate_control_ops_get(alg_name);
113	if (!ops) {
114		request_module("rc80211_%s", alg_name);
115		ops = ieee80211_try_rate_control_ops_get(alg_name);
116	}
117	if (!ops && name)
118		/* try default if specific alg requested but not found */
119		ops = ieee80211_try_rate_control_ops_get(ieee80211_default_rc_algo);
120
121	/* try built-in one if specific alg requested but not found */
122	if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
123		ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
124	kparam_unblock_sysfs_write(ieee80211_default_rc_algo);
125
126	return ops;
127}
128
129static void ieee80211_rate_control_ops_put(struct rate_control_ops *ops)
130{
131	module_put(ops->module);
132}
133
134#ifdef CONFIG_MAC80211_DEBUGFS
135static ssize_t rcname_read(struct file *file, char __user *userbuf,
136			   size_t count, loff_t *ppos)
137{
138	struct rate_control_ref *ref = file->private_data;
139	int len = strlen(ref->ops->name);
140
141	return simple_read_from_buffer(userbuf, count, ppos,
142				       ref->ops->name, len);
143}
144
145static const struct file_operations rcname_ops = {
146	.read = rcname_read,
147	.open = mac80211_open_file_generic,
148};
149#endif
150
151static struct rate_control_ref *rate_control_alloc(const char *name,
152					    struct ieee80211_local *local)
153{
154	struct dentry *debugfsdir = NULL;
155	struct rate_control_ref *ref;
156
157	ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
158	if (!ref)
159		goto fail_ref;
160	kref_init(&ref->kref);
161	ref->local = local;
162	ref->ops = ieee80211_rate_control_ops_get(name);
163	if (!ref->ops)
164		goto fail_ops;
165
166#ifdef CONFIG_MAC80211_DEBUGFS
167	debugfsdir = debugfs_create_dir("rc", local->hw.wiphy->debugfsdir);
168	local->debugfs.rcdir = debugfsdir;
169	debugfs_create_file("name", 0400, debugfsdir, ref, &rcname_ops);
170#endif
171
172	ref->priv = ref->ops->alloc(&local->hw, debugfsdir);
173	if (!ref->priv)
174		goto fail_priv;
175	return ref;
176
177fail_priv:
178	ieee80211_rate_control_ops_put(ref->ops);
179fail_ops:
180	kfree(ref);
181fail_ref:
182	return NULL;
183}
184
185static void rate_control_release(struct kref *kref)
186{
187	struct rate_control_ref *ctrl_ref;
188
189	ctrl_ref = container_of(kref, struct rate_control_ref, kref);
190	ctrl_ref->ops->free(ctrl_ref->priv);
191
192#ifdef CONFIG_MAC80211_DEBUGFS
193	debugfs_remove_recursive(ctrl_ref->local->debugfs.rcdir);
194	ctrl_ref->local->debugfs.rcdir = NULL;
195#endif
196
197	ieee80211_rate_control_ops_put(ctrl_ref->ops);
198	kfree(ctrl_ref);
199}
200
201static bool rc_no_data_or_no_ack(struct ieee80211_tx_rate_control *txrc)
202{
203	struct sk_buff *skb = txrc->skb;
204	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
205	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
206	__le16 fc;
207
208	fc = hdr->frame_control;
209
210	return (info->flags & IEEE80211_TX_CTL_NO_ACK) || !ieee80211_is_data(fc);
211}
212
213static void rc_send_low_broadcast(s8 *idx, u32 basic_rates, u8 max_rate_idx)
214{
215	u8 i;
216
217	if (basic_rates == 0)
218		return; /* assume basic rates unknown and accept rate */
219	if (*idx < 0)
220		return;
221	if (basic_rates & (1 << *idx))
222		return; /* selected rate is a basic rate */
223
224	for (i = *idx + 1; i <= max_rate_idx; i++) {
225		if (basic_rates & (1 << i)) {
226			*idx = i;
227			return;
228		}
229	}
230
231	/* could not find a basic rate; use original selection */
232}
233
234bool rate_control_send_low(struct ieee80211_sta *sta,
235			   void *priv_sta,
236			   struct ieee80211_tx_rate_control *txrc)
237{
238	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
239
240	if (!sta || !priv_sta || rc_no_data_or_no_ack(txrc)) {
241		info->control.rates[0].idx = rate_lowest_index(txrc->sband, sta);
242		info->control.rates[0].count =
243			(info->flags & IEEE80211_TX_CTL_NO_ACK) ?
244			1 : txrc->hw->max_rate_tries;
245		if (!sta && txrc->ap)
246			rc_send_low_broadcast(&info->control.rates[0].idx,
247					      txrc->bss_conf->basic_rates,
248					      txrc->sband->n_bitrates);
249		return true;
250	}
251	return false;
252}
253EXPORT_SYMBOL(rate_control_send_low);
254
255static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
256				int n_bitrates, u32 mask)
257{
258	int j;
259
260	/* See whether the selected rate or anything below it is allowed. */
261	for (j = rate->idx; j >= 0; j--) {
262		if (mask & (1 << j)) {
263			/* Okay, found a suitable rate. Use it. */
264			rate->idx = j;
265			return;
266		}
267	}
268
269	/* Try to find a higher rate that would be allowed */
270	for (j = rate->idx + 1; j < n_bitrates; j++) {
271		if (mask & (1 << j)) {
272			/* Okay, found a suitable rate. Use it. */
273			rate->idx = j;
274			return;
275		}
276	}
277
278	/*
279	 * Uh.. No suitable rate exists. This should not really happen with
280	 * sane TX rate mask configurations. However, should someone manage to
281	 * configure supported rates and TX rate mask in incompatible way,
282	 * allow the frame to be transmitted with whatever the rate control
283	 * selected.
284	 */
285}
286
287void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
288			   struct sta_info *sta,
289			   struct ieee80211_tx_rate_control *txrc)
290{
291	struct rate_control_ref *ref = sdata->local->rate_ctrl;
292	void *priv_sta = NULL;
293	struct ieee80211_sta *ista = NULL;
294	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
295	int i;
296	u32 mask;
297
298	if (sta) {
299		ista = &sta->sta;
300		priv_sta = sta->rate_ctrl_priv;
301	}
302
303	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
304		info->control.rates[i].idx = -1;
305		info->control.rates[i].flags = 0;
306		info->control.rates[i].count = 1;
307	}
308
309	if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
310		return;
311
312	ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
313
314	/*
315	 * Try to enforce the rateidx mask the user wanted. skip this if the
316	 * default mask (allow all rates) is used to save some processing for
317	 * the common case.
318	 */
319	mask = sdata->rc_rateidx_mask[info->band];
320	if (mask != (1 << txrc->sband->n_bitrates) - 1) {
321		if (sta) {
322			/* Filter out rates that the STA does not support */
323			mask &= sta->sta.supp_rates[info->band];
324		}
325		/*
326		 * Make sure the rate index selected for each TX rate is
327		 * included in the configured mask and change the rate indexes
328		 * if needed.
329		 */
330		for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
331			/* Rate masking supports only legacy rates for now */
332			if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS)
333				continue;
334			rate_idx_match_mask(&info->control.rates[i],
335					    txrc->sband->n_bitrates, mask);
336		}
337	}
338
339	BUG_ON(info->control.rates[0].idx < 0);
340}
341
342struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
343{
344	kref_get(&ref->kref);
345	return ref;
346}
347
348void rate_control_put(struct rate_control_ref *ref)
349{
350	kref_put(&ref->kref, rate_control_release);
351}
352
353int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
354				 const char *name)
355{
356	struct rate_control_ref *ref, *old;
357
358	ASSERT_RTNL();
359
360	if (local->open_count)
361		return -EBUSY;
362
363	if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
364		if (WARN_ON(!local->ops->set_rts_threshold))
365			return -EINVAL;
366		return 0;
367	}
368
369	ref = rate_control_alloc(name, local);
370	if (!ref) {
371		wiphy_warn(local->hw.wiphy,
372			   "Failed to select rate control algorithm\n");
373		return -ENOENT;
374	}
375
376	old = local->rate_ctrl;
377	local->rate_ctrl = ref;
378	if (old) {
379		rate_control_put(old);
380		sta_info_flush(local, NULL);
381	}
382
383	wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
384		    ref->ops->name);
385
386	return 0;
387}
388
389void rate_control_deinitialize(struct ieee80211_local *local)
390{
391	struct rate_control_ref *ref;
392
393	ref = local->rate_ctrl;
394
395	if (!ref)
396		return;
397
398	local->rate_ctrl = NULL;
399	rate_control_put(ref);
400}
401
402