rate.c revision aad14ceb45f5ff12da2ab5b37a596e6f81566515 
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	.llseek = default_llseek,
149};
150#endif
151
152static struct rate_control_ref *rate_control_alloc(const char *name,
153					    struct ieee80211_local *local)
154{
155	struct dentry *debugfsdir = NULL;
156	struct rate_control_ref *ref;
157
158	ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
159	if (!ref)
160		goto fail_ref;
161	kref_init(&ref->kref);
162	ref->local = local;
163	ref->ops = ieee80211_rate_control_ops_get(name);
164	if (!ref->ops)
165		goto fail_ops;
166
167#ifdef CONFIG_MAC80211_DEBUGFS
168	debugfsdir = debugfs_create_dir("rc", local->hw.wiphy->debugfsdir);
169	local->debugfs.rcdir = debugfsdir;
170	debugfs_create_file("name", 0400, debugfsdir, ref, &rcname_ops);
171#endif
172
173	ref->priv = ref->ops->alloc(&local->hw, debugfsdir);
174	if (!ref->priv)
175		goto fail_priv;
176	return ref;
177
178fail_priv:
179	ieee80211_rate_control_ops_put(ref->ops);
180fail_ops:
181	kfree(ref);
182fail_ref:
183	return NULL;
184}
185
186static void rate_control_release(struct kref *kref)
187{
188	struct rate_control_ref *ctrl_ref;
189
190	ctrl_ref = container_of(kref, struct rate_control_ref, kref);
191	ctrl_ref->ops->free(ctrl_ref->priv);
192
193#ifdef CONFIG_MAC80211_DEBUGFS
194	debugfs_remove_recursive(ctrl_ref->local->debugfs.rcdir);
195	ctrl_ref->local->debugfs.rcdir = NULL;
196#endif
197
198	ieee80211_rate_control_ops_put(ctrl_ref->ops);
199	kfree(ctrl_ref);
200}
201
202static bool rc_no_data_or_no_ack(struct ieee80211_tx_rate_control *txrc)
203{
204	struct sk_buff *skb = txrc->skb;
205	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
206	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
207	__le16 fc;
208
209	fc = hdr->frame_control;
210
211	return (info->flags & IEEE80211_TX_CTL_NO_ACK) || !ieee80211_is_data(fc);
212}
213
214static void rc_send_low_broadcast(s8 *idx, u32 basic_rates,
215				  struct ieee80211_supported_band *sband)
216{
217	u8 i;
218
219	if (basic_rates == 0)
220		return; /* assume basic rates unknown and accept rate */
221	if (*idx < 0)
222		return;
223	if (basic_rates & (1 << *idx))
224		return; /* selected rate is a basic rate */
225
226	for (i = *idx + 1; i <= sband->n_bitrates; i++) {
227		if (basic_rates & (1 << i)) {
228			*idx = i;
229			return;
230		}
231	}
232
233	/* could not find a basic rate; use original selection */
234}
235
236static inline s8
237rate_lowest_non_cck_index(struct ieee80211_supported_band *sband,
238			  struct ieee80211_sta *sta)
239{
240	int i;
241
242	for (i = 0; i < sband->n_bitrates; i++) {
243		struct ieee80211_rate *srate = &sband->bitrates[i];
244		if ((srate->bitrate == 10) || (srate->bitrate == 20) ||
245		    (srate->bitrate == 55) || (srate->bitrate == 110))
246			continue;
247
248		if (rate_supported(sta, sband->band, i))
249			return i;
250	}
251
252	/* No matching rate found */
253	return 0;
254}
255
256
257bool rate_control_send_low(struct ieee80211_sta *sta,
258			   void *priv_sta,
259			   struct ieee80211_tx_rate_control *txrc)
260{
261	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
262	struct ieee80211_supported_band *sband = txrc->sband;
263	int mcast_rate;
264
265	if (!sta || !priv_sta || rc_no_data_or_no_ack(txrc)) {
266		if ((sband->band != IEEE80211_BAND_2GHZ) ||
267		    !(info->flags & IEEE80211_TX_CTL_NO_CCK_RATE))
268			info->control.rates[0].idx =
269				rate_lowest_index(txrc->sband, sta);
270		else
271			info->control.rates[0].idx =
272				rate_lowest_non_cck_index(txrc->sband, sta);
273		info->control.rates[0].count =
274			(info->flags & IEEE80211_TX_CTL_NO_ACK) ?
275			1 : txrc->hw->max_rate_tries;
276		if (!sta && txrc->bss) {
277			mcast_rate = txrc->bss_conf->mcast_rate[sband->band];
278			if (mcast_rate > 0) {
279				info->control.rates[0].idx = mcast_rate - 1;
280				return true;
281			}
282
283			rc_send_low_broadcast(&info->control.rates[0].idx,
284					      txrc->bss_conf->basic_rates,
285					      sband);
286		}
287		return true;
288	}
289	return false;
290}
291EXPORT_SYMBOL(rate_control_send_low);
292
293static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
294				int n_bitrates, u32 mask)
295{
296	int j;
297
298	/* See whether the selected rate or anything below it is allowed. */
299	for (j = rate->idx; j >= 0; j--) {
300		if (mask & (1 << j)) {
301			/* Okay, found a suitable rate. Use it. */
302			rate->idx = j;
303			return;
304		}
305	}
306
307	/* Try to find a higher rate that would be allowed */
308	for (j = rate->idx + 1; j < n_bitrates; j++) {
309		if (mask & (1 << j)) {
310			/* Okay, found a suitable rate. Use it. */
311			rate->idx = j;
312			return;
313		}
314	}
315
316	/*
317	 * Uh.. No suitable rate exists. This should not really happen with
318	 * sane TX rate mask configurations. However, should someone manage to
319	 * configure supported rates and TX rate mask in incompatible way,
320	 * allow the frame to be transmitted with whatever the rate control
321	 * selected.
322	 */
323}
324
325void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
326			   struct sta_info *sta,
327			   struct ieee80211_tx_rate_control *txrc)
328{
329	struct rate_control_ref *ref = sdata->local->rate_ctrl;
330	void *priv_sta = NULL;
331	struct ieee80211_sta *ista = NULL;
332	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
333	int i;
334	u32 mask;
335
336	if (sta) {
337		ista = &sta->sta;
338		priv_sta = sta->rate_ctrl_priv;
339	}
340
341	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
342		info->control.rates[i].idx = -1;
343		info->control.rates[i].flags = 0;
344		info->control.rates[i].count = 1;
345	}
346
347	if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
348		return;
349
350	ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
351
352	/*
353	 * Try to enforce the rateidx mask the user wanted. skip this if the
354	 * default mask (allow all rates) is used to save some processing for
355	 * the common case.
356	 */
357	mask = sdata->rc_rateidx_mask[info->band];
358	if (mask != (1 << txrc->sband->n_bitrates) - 1) {
359		if (sta) {
360			/* Filter out rates that the STA does not support */
361			mask &= sta->sta.supp_rates[info->band];
362		}
363		/*
364		 * Make sure the rate index selected for each TX rate is
365		 * included in the configured mask and change the rate indexes
366		 * if needed.
367		 */
368		for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
369			/* Skip invalid rates */
370			if (info->control.rates[i].idx < 0)
371				break;
372			/* Rate masking supports only legacy rates for now */
373			if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS)
374				continue;
375			rate_idx_match_mask(&info->control.rates[i],
376					    txrc->sband->n_bitrates, mask);
377		}
378	}
379
380	BUG_ON(info->control.rates[0].idx < 0);
381}
382
383struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
384{
385	kref_get(&ref->kref);
386	return ref;
387}
388
389void rate_control_put(struct rate_control_ref *ref)
390{
391	kref_put(&ref->kref, rate_control_release);
392}
393
394int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
395				 const char *name)
396{
397	struct rate_control_ref *ref, *old;
398
399	ASSERT_RTNL();
400
401	if (local->open_count)
402		return -EBUSY;
403
404	if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
405		if (WARN_ON(!local->ops->set_rts_threshold))
406			return -EINVAL;
407		return 0;
408	}
409
410	ref = rate_control_alloc(name, local);
411	if (!ref) {
412		wiphy_warn(local->hw.wiphy,
413			   "Failed to select rate control algorithm\n");
414		return -ENOENT;
415	}
416
417	old = local->rate_ctrl;
418	local->rate_ctrl = ref;
419	if (old) {
420		rate_control_put(old);
421		sta_info_flush(local, NULL);
422	}
423
424	wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
425		    ref->ops->name);
426
427	return 0;
428}
429
430void rate_control_deinitialize(struct ieee80211_local *local)
431{
432	struct rate_control_ref *ref;
433
434	ref = local->rate_ctrl;
435
436	if (!ref)
437		return;
438
439	local->rate_ctrl = NULL;
440	rate_control_put(ref);
441}
442
443