summaryrefslogtreecommitdiffstats
path: root/net/mac80211/rate.c
blob: ad64f4d5271a58121f93cf7f62806c93687d1193 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
/*
 * 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 <linux/slab.h>
#include <linux/module.h>
#include "rate.h"
#include "ieee80211_i.h"
#include "debugfs.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;

	kparam_block_sysfs_write(ieee80211_default_rc_algo);
	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);
	kparam_unblock_sysfs_write(ieee80211_default_rc_algo);

	return ops;
}

static void ieee80211_rate_control_ops_put(struct rate_control_ops *ops)
{
	module_put(ops->module);
}

#ifdef CONFIG_MAC80211_DEBUGFS
static ssize_t rcname_read(struct file *file, char __user *userbuf,
			   size_t count, loff_t *ppos)
{
	struct rate_control_ref *ref = file->private_data;
	int len = strlen(ref->ops->name);

	return simple_read_from_buffer(userbuf, count, ppos,
				       ref->ops->name, len);
}

static const struct file_operations rcname_ops = {
	.read = rcname_read,
	.open = mac80211_open_file_generic,
	.llseek = default_llseek,
};
#endif

static struct rate_control_ref *rate_control_alloc(const char *name,
					    struct ieee80211_local *local)
{
	struct dentry *debugfsdir = NULL;
	struct rate_control_ref *ref;

	ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
	if (!ref)
		goto fail_ref;
	kref_init(&ref->kref);
	ref->local = local;
	ref->ops = ieee80211_rate_control_ops_get(name);
	if (!ref->ops)
		goto fail_ops;

#ifdef CONFIG_MAC80211_DEBUGFS
	debugfsdir = debugfs_create_dir("rc", local->hw.wiphy->debugfsdir);
	local->debugfs.rcdir = debugfsdir;
	debugfs_create_file("name", 0400, debugfsdir, ref, &rcname_ops);
#endif

	ref->priv = ref->ops->alloc(&local->hw, debugfsdir);
	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);

#ifdef CONFIG_MAC80211_DEBUGFS
	debugfs_remove_recursive(ctrl_ref->local->debugfs.rcdir);
	ctrl_ref->local->debugfs.rcdir = NULL;
#endif

	ieee80211_rate_control_ops_put(ctrl_ref->ops);
	kfree(ctrl_ref);
}

static bool rc_no_data_or_no_ack_use_min(struct ieee80211_tx_rate_control *txrc)
{
	struct sk_buff *skb = txrc->skb;
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	__le16 fc;

	fc = hdr->frame_control;

	return (info->flags & (IEEE80211_TX_CTL_NO_ACK |
			       IEEE80211_TX_CTL_USE_MINRATE)) ||
		!ieee80211_is_data(fc);
}

static void rc_send_low_broadcast(s8 *idx, u32 basic_rates,
				  struct ieee80211_supported_band *sband)
{
	u8 i;

	if (basic_rates == 0)
		return; /* assume basic rates unknown and accept rate */
	if (*idx < 0)
		return;
	if (basic_rates & (1 << *idx))
		return; /* selected rate is a basic rate */

	for (i = *idx + 1; i <= sband->n_bitrates; i++) {
		if (basic_rates & (1 << i)) {
			*idx = i;
			return;
		}
	}

	/* could not find a basic rate; use original selection */
}

static inline s8
rate_lowest_non_cck_index(struct ieee80211_supported_band *sband,
			  struct ieee80211_sta *sta)
{
	int i;

	for (i = 0; i < sband->n_bitrates; i++) {
		struct ieee80211_rate *srate = &sband->bitrates[i];
		if ((srate->bitrate == 10) || (srate->bitrate == 20) ||
		    (srate->bitrate == 55) || (srate->bitrate == 110))
			continue;

		if (rate_supported(sta, sband->band, i))
			return i;
	}

	/* No matching rate found */
	return 0;
}


bool rate_control_send_low(struct ieee80211_sta *sta,
			   void *priv_sta,
			   struct ieee80211_tx_rate_control *txrc)
{
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
	struct ieee80211_supported_band *sband = txrc->sband;
	int mcast_rate;

	if (!sta || !priv_sta || rc_no_data_or_no_ack_use_min(txrc)) {
		if ((sband->band != IEEE80211_BAND_2GHZ) ||
		    !(info->flags & IEEE80211_TX_CTL_NO_CCK_RATE))
			info->control.rates[0].idx =
				rate_lowest_index(txrc->sband, sta);
		else
			info->control.rates[0].idx =
				rate_lowest_non_cck_index(txrc->sband, sta);
		info->control.rates[0].count =
			(info->flags & IEEE80211_TX_CTL_NO_ACK) ?
			1 : txrc->hw->max_rate_tries;
		if (!sta && txrc->bss) {
			mcast_rate = txrc->bss_conf->mcast_rate[sband->band];
			if (mcast_rate > 0) {
				info->control.rates[0].idx = mcast_rate - 1;
				return true;
			}

			rc_send_low_broadcast(&info->control.rates[0].idx,
					      txrc->bss_conf->basic_rates,
					      sband);
		}
		return true;
	}
	return false;
}
EXPORT_SYMBOL(rate_control_send_low);

static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
				int n_bitrates, u32 mask)
{
	int j;

	/* See whether the selected rate or anything below it is allowed. */
	for (j = rate->idx; j >= 0; j--) {
		if (mask & (1 << j)) {
			/* Okay, found a suitable rate. Use it. */
			rate->idx = j;
			return;
		}
	}

	/* Try to find a higher rate that would be allowed */
	for (j = rate->idx + 1; j < n_bitrates; j++) {
		if (mask & (1 << j)) {
			/* Okay, found a suitable rate. Use it. */
			rate->idx = j;
			return;
		}
	}

	/*
	 * Uh.. No suitable rate exists. This should not really happen with
	 * sane TX rate mask configurations. However, should someone manage to
	 * configure supported rates and TX rate mask in incompatible way,
	 * allow the frame to be transmitted with whatever the rate control
	 * selected.
	 */
}

void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
			   struct sta_info *sta,
			   struct ieee80211_tx_rate_control *txrc)
{
	struct rate_control_ref *ref = sdata->local->rate_ctrl;
	void *priv_sta = NULL;
	struct ieee80211_sta *ista = NULL;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
	int i;
	u32 mask;

	if (sta && test_sta_flag(sta, WLAN_STA_RATE_CONTROL)) {
		ista = &sta->sta;
		priv_sta = sta->rate_ctrl_priv;
	}

	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
		info->control.rates[i].idx = -1;
		info->control.rates[i].flags = 0;
		info->control.rates[i].count = 1;
	}

	if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
		return;

	ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);

	/*
	 * Try to enforce the rateidx mask the user wanted. skip this if the
	 * default mask (allow all rates) is used to save some processing for
	 * the common case.
	 */
	mask = sdata->rc_rateidx_mask[info->band];
	if (mask != (1 << txrc->sband->n_bitrates) - 1) {
		if (sta) {
			/* Filter out rates that the STA does not support */
			mask &= sta->sta.supp_rates[info->band];
		}
		/*
		 * Make sure the rate index selected for each TX rate is
		 * included in the configured mask and change the rate indexes
		 * if needed.
		 */
		for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
			/* Skip invalid rates */
			if (info->control.rates[i].idx < 0)
				break;
			/* Rate masking supports only legacy rates for now */
			if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS)
				continue;
			rate_idx_match_mask(&info->control.rates[i],
					    txrc->sband->n_bitrates, mask);
		}
	}

	BUG_ON(info->control.rates[0].idx < 0);
}

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)
		return -EBUSY;

	if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
		if (WARN_ON(!local->ops->set_rts_threshold))
			return -EINVAL;
		return 0;
	}

	ref = rate_control_alloc(name, local);
	if (!ref) {
		wiphy_warn(local->hw.wiphy,
			   "Failed to select rate control algorithm\n");
		return -ENOENT;
	}

	old = local->rate_ctrl;
	local->rate_ctrl = ref;
	if (old) {
		rate_control_put(old);
		sta_info_flush(local, NULL);
	}

	wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
		    ref->ops->name);

	return 0;
}

void rate_control_deinitialize(struct ieee80211_local *local)
{
	struct rate_control_ref *ref;

	ref = local->rate_ctrl;

	if (!ref)
		return;

	local->rate_ctrl = NULL;
	rate_control_put(ref);
}