xref: /openbmc/linux/net/mac80211/rate.c (revision eb3fcf00)
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/module.h>
14 #include <linux/slab.h>
15 #include "rate.h"
16 #include "ieee80211_i.h"
17 #include "debugfs.h"
18 
19 struct rate_control_alg {
20 	struct list_head list;
21 	const struct rate_control_ops *ops;
22 };
23 
24 static LIST_HEAD(rate_ctrl_algs);
25 static DEFINE_MUTEX(rate_ctrl_mutex);
26 
27 static char *ieee80211_default_rc_algo = CONFIG_MAC80211_RC_DEFAULT;
28 module_param(ieee80211_default_rc_algo, charp, 0644);
29 MODULE_PARM_DESC(ieee80211_default_rc_algo,
30 		 "Default rate control algorithm for mac80211 to use");
31 
32 void rate_control_rate_init(struct sta_info *sta)
33 {
34 	struct ieee80211_local *local = sta->sdata->local;
35 	struct rate_control_ref *ref = sta->rate_ctrl;
36 	struct ieee80211_sta *ista = &sta->sta;
37 	void *priv_sta = sta->rate_ctrl_priv;
38 	struct ieee80211_supported_band *sband;
39 	struct ieee80211_chanctx_conf *chanctx_conf;
40 
41 	ieee80211_sta_set_rx_nss(sta);
42 
43 	if (!ref)
44 		return;
45 
46 	rcu_read_lock();
47 
48 	chanctx_conf = rcu_dereference(sta->sdata->vif.chanctx_conf);
49 	if (WARN_ON(!chanctx_conf)) {
50 		rcu_read_unlock();
51 		return;
52 	}
53 
54 	sband = local->hw.wiphy->bands[chanctx_conf->def.chan->band];
55 
56 	spin_lock_bh(&sta->rate_ctrl_lock);
57 	ref->ops->rate_init(ref->priv, sband, &chanctx_conf->def, ista,
58 			    priv_sta);
59 	spin_unlock_bh(&sta->rate_ctrl_lock);
60 	rcu_read_unlock();
61 	set_sta_flag(sta, WLAN_STA_RATE_CONTROL);
62 }
63 
64 void rate_control_rate_update(struct ieee80211_local *local,
65 				    struct ieee80211_supported_band *sband,
66 				    struct sta_info *sta, u32 changed)
67 {
68 	struct rate_control_ref *ref = local->rate_ctrl;
69 	struct ieee80211_sta *ista = &sta->sta;
70 	void *priv_sta = sta->rate_ctrl_priv;
71 	struct ieee80211_chanctx_conf *chanctx_conf;
72 
73 	if (ref && ref->ops->rate_update) {
74 		rcu_read_lock();
75 
76 		chanctx_conf = rcu_dereference(sta->sdata->vif.chanctx_conf);
77 		if (WARN_ON(!chanctx_conf)) {
78 			rcu_read_unlock();
79 			return;
80 		}
81 
82 		spin_lock_bh(&sta->rate_ctrl_lock);
83 		ref->ops->rate_update(ref->priv, sband, &chanctx_conf->def,
84 				      ista, priv_sta, changed);
85 		spin_unlock_bh(&sta->rate_ctrl_lock);
86 		rcu_read_unlock();
87 	}
88 	drv_sta_rc_update(local, sta->sdata, &sta->sta, changed);
89 }
90 
91 int ieee80211_rate_control_register(const struct rate_control_ops *ops)
92 {
93 	struct rate_control_alg *alg;
94 
95 	if (!ops->name)
96 		return -EINVAL;
97 
98 	mutex_lock(&rate_ctrl_mutex);
99 	list_for_each_entry(alg, &rate_ctrl_algs, list) {
100 		if (!strcmp(alg->ops->name, ops->name)) {
101 			/* don't register an algorithm twice */
102 			WARN_ON(1);
103 			mutex_unlock(&rate_ctrl_mutex);
104 			return -EALREADY;
105 		}
106 	}
107 
108 	alg = kzalloc(sizeof(*alg), GFP_KERNEL);
109 	if (alg == NULL) {
110 		mutex_unlock(&rate_ctrl_mutex);
111 		return -ENOMEM;
112 	}
113 	alg->ops = ops;
114 
115 	list_add_tail(&alg->list, &rate_ctrl_algs);
116 	mutex_unlock(&rate_ctrl_mutex);
117 
118 	return 0;
119 }
120 EXPORT_SYMBOL(ieee80211_rate_control_register);
121 
122 void ieee80211_rate_control_unregister(const struct rate_control_ops *ops)
123 {
124 	struct rate_control_alg *alg;
125 
126 	mutex_lock(&rate_ctrl_mutex);
127 	list_for_each_entry(alg, &rate_ctrl_algs, list) {
128 		if (alg->ops == ops) {
129 			list_del(&alg->list);
130 			kfree(alg);
131 			break;
132 		}
133 	}
134 	mutex_unlock(&rate_ctrl_mutex);
135 }
136 EXPORT_SYMBOL(ieee80211_rate_control_unregister);
137 
138 static const struct rate_control_ops *
139 ieee80211_try_rate_control_ops_get(const char *name)
140 {
141 	struct rate_control_alg *alg;
142 	const struct rate_control_ops *ops = NULL;
143 
144 	if (!name)
145 		return NULL;
146 
147 	mutex_lock(&rate_ctrl_mutex);
148 	list_for_each_entry(alg, &rate_ctrl_algs, list) {
149 		if (!strcmp(alg->ops->name, name)) {
150 			ops = alg->ops;
151 			break;
152 		}
153 	}
154 	mutex_unlock(&rate_ctrl_mutex);
155 	return ops;
156 }
157 
158 /* Get the rate control algorithm. */
159 static const struct rate_control_ops *
160 ieee80211_rate_control_ops_get(const char *name)
161 {
162 	const struct rate_control_ops *ops;
163 	const char *alg_name;
164 
165 	kernel_param_lock(THIS_MODULE);
166 	if (!name)
167 		alg_name = ieee80211_default_rc_algo;
168 	else
169 		alg_name = name;
170 
171 	ops = ieee80211_try_rate_control_ops_get(alg_name);
172 	if (!ops && name)
173 		/* try default if specific alg requested but not found */
174 		ops = ieee80211_try_rate_control_ops_get(ieee80211_default_rc_algo);
175 
176 	/* try built-in one if specific alg requested but not found */
177 	if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
178 		ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
179 	kernel_param_unlock(THIS_MODULE);
180 
181 	return ops;
182 }
183 
184 #ifdef CONFIG_MAC80211_DEBUGFS
185 static ssize_t rcname_read(struct file *file, char __user *userbuf,
186 			   size_t count, loff_t *ppos)
187 {
188 	struct rate_control_ref *ref = file->private_data;
189 	int len = strlen(ref->ops->name);
190 
191 	return simple_read_from_buffer(userbuf, count, ppos,
192 				       ref->ops->name, len);
193 }
194 
195 static const struct file_operations rcname_ops = {
196 	.read = rcname_read,
197 	.open = simple_open,
198 	.llseek = default_llseek,
199 };
200 #endif
201 
202 static struct rate_control_ref *rate_control_alloc(const char *name,
203 					    struct ieee80211_local *local)
204 {
205 	struct dentry *debugfsdir = NULL;
206 	struct rate_control_ref *ref;
207 
208 	ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
209 	if (!ref)
210 		return NULL;
211 	ref->local = local;
212 	ref->ops = ieee80211_rate_control_ops_get(name);
213 	if (!ref->ops)
214 		goto free;
215 
216 #ifdef CONFIG_MAC80211_DEBUGFS
217 	debugfsdir = debugfs_create_dir("rc", local->hw.wiphy->debugfsdir);
218 	local->debugfs.rcdir = debugfsdir;
219 	debugfs_create_file("name", 0400, debugfsdir, ref, &rcname_ops);
220 #endif
221 
222 	ref->priv = ref->ops->alloc(&local->hw, debugfsdir);
223 	if (!ref->priv)
224 		goto free;
225 	return ref;
226 
227 free:
228 	kfree(ref);
229 	return NULL;
230 }
231 
232 static void rate_control_free(struct rate_control_ref *ctrl_ref)
233 {
234 	ctrl_ref->ops->free(ctrl_ref->priv);
235 
236 #ifdef CONFIG_MAC80211_DEBUGFS
237 	debugfs_remove_recursive(ctrl_ref->local->debugfs.rcdir);
238 	ctrl_ref->local->debugfs.rcdir = NULL;
239 #endif
240 
241 	kfree(ctrl_ref);
242 }
243 
244 static bool rc_no_data_or_no_ack_use_min(struct ieee80211_tx_rate_control *txrc)
245 {
246 	struct sk_buff *skb = txrc->skb;
247 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
248 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
249 	__le16 fc;
250 
251 	fc = hdr->frame_control;
252 
253 	return (info->flags & (IEEE80211_TX_CTL_NO_ACK |
254 			       IEEE80211_TX_CTL_USE_MINRATE)) ||
255 		!ieee80211_is_data(fc);
256 }
257 
258 static void rc_send_low_basicrate(s8 *idx, u32 basic_rates,
259 				  struct ieee80211_supported_band *sband)
260 {
261 	u8 i;
262 
263 	if (basic_rates == 0)
264 		return; /* assume basic rates unknown and accept rate */
265 	if (*idx < 0)
266 		return;
267 	if (basic_rates & (1 << *idx))
268 		return; /* selected rate is a basic rate */
269 
270 	for (i = *idx + 1; i <= sband->n_bitrates; i++) {
271 		if (basic_rates & (1 << i)) {
272 			*idx = i;
273 			return;
274 		}
275 	}
276 
277 	/* could not find a basic rate; use original selection */
278 }
279 
280 static void __rate_control_send_low(struct ieee80211_hw *hw,
281 				    struct ieee80211_supported_band *sband,
282 				    struct ieee80211_sta *sta,
283 				    struct ieee80211_tx_info *info,
284 				    u32 rate_mask)
285 {
286 	int i;
287 	u32 rate_flags =
288 		ieee80211_chandef_rate_flags(&hw->conf.chandef);
289 
290 	if ((sband->band == IEEE80211_BAND_2GHZ) &&
291 	    (info->flags & IEEE80211_TX_CTL_NO_CCK_RATE))
292 		rate_flags |= IEEE80211_RATE_ERP_G;
293 
294 	info->control.rates[0].idx = 0;
295 	for (i = 0; i < sband->n_bitrates; i++) {
296 		if (!(rate_mask & BIT(i)))
297 			continue;
298 
299 		if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
300 			continue;
301 
302 		if (!rate_supported(sta, sband->band, i))
303 			continue;
304 
305 		info->control.rates[0].idx = i;
306 		break;
307 	}
308 	WARN_ON_ONCE(i == sband->n_bitrates);
309 
310 	info->control.rates[0].count =
311 		(info->flags & IEEE80211_TX_CTL_NO_ACK) ?
312 		1 : hw->max_rate_tries;
313 
314 	info->control.skip_table = 1;
315 }
316 
317 
318 bool rate_control_send_low(struct ieee80211_sta *pubsta,
319 			   void *priv_sta,
320 			   struct ieee80211_tx_rate_control *txrc)
321 {
322 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
323 	struct ieee80211_supported_band *sband = txrc->sband;
324 	struct sta_info *sta;
325 	int mcast_rate;
326 	bool use_basicrate = false;
327 
328 	if (!pubsta || !priv_sta || rc_no_data_or_no_ack_use_min(txrc)) {
329 		__rate_control_send_low(txrc->hw, sband, pubsta, info,
330 					txrc->rate_idx_mask);
331 
332 		if (!pubsta && txrc->bss) {
333 			mcast_rate = txrc->bss_conf->mcast_rate[sband->band];
334 			if (mcast_rate > 0) {
335 				info->control.rates[0].idx = mcast_rate - 1;
336 				return true;
337 			}
338 			use_basicrate = true;
339 		} else if (pubsta) {
340 			sta = container_of(pubsta, struct sta_info, sta);
341 			if (ieee80211_vif_is_mesh(&sta->sdata->vif))
342 				use_basicrate = true;
343 		}
344 
345 		if (use_basicrate)
346 			rc_send_low_basicrate(&info->control.rates[0].idx,
347 					      txrc->bss_conf->basic_rates,
348 					      sband);
349 
350 		return true;
351 	}
352 	return false;
353 }
354 EXPORT_SYMBOL(rate_control_send_low);
355 
356 static bool rate_idx_match_legacy_mask(s8 *rate_idx, int n_bitrates, u32 mask)
357 {
358 	int j;
359 
360 	/* See whether the selected rate or anything below it is allowed. */
361 	for (j = *rate_idx; j >= 0; j--) {
362 		if (mask & (1 << j)) {
363 			/* Okay, found a suitable rate. Use it. */
364 			*rate_idx = j;
365 			return true;
366 		}
367 	}
368 
369 	/* Try to find a higher rate that would be allowed */
370 	for (j = *rate_idx + 1; j < n_bitrates; j++) {
371 		if (mask & (1 << j)) {
372 			/* Okay, found a suitable rate. Use it. */
373 			*rate_idx = j;
374 			return true;
375 		}
376 	}
377 	return false;
378 }
379 
380 static bool rate_idx_match_mcs_mask(s8 *rate_idx, u8 *mcs_mask)
381 {
382 	int i, j;
383 	int ridx, rbit;
384 
385 	ridx = *rate_idx / 8;
386 	rbit = *rate_idx % 8;
387 
388 	/* sanity check */
389 	if (ridx < 0 || ridx >= IEEE80211_HT_MCS_MASK_LEN)
390 		return false;
391 
392 	/* See whether the selected rate or anything below it is allowed. */
393 	for (i = ridx; i >= 0; i--) {
394 		for (j = rbit; j >= 0; j--)
395 			if (mcs_mask[i] & BIT(j)) {
396 				*rate_idx = i * 8 + j;
397 				return true;
398 			}
399 		rbit = 7;
400 	}
401 
402 	/* Try to find a higher rate that would be allowed */
403 	ridx = (*rate_idx + 1) / 8;
404 	rbit = (*rate_idx + 1) % 8;
405 
406 	for (i = ridx; i < IEEE80211_HT_MCS_MASK_LEN; i++) {
407 		for (j = rbit; j < 8; j++)
408 			if (mcs_mask[i] & BIT(j)) {
409 				*rate_idx = i * 8 + j;
410 				return true;
411 			}
412 		rbit = 0;
413 	}
414 	return false;
415 }
416 
417 static bool rate_idx_match_vht_mcs_mask(s8 *rate_idx, u16 *vht_mask)
418 {
419 	int i, j;
420 	int ridx, rbit;
421 
422 	ridx = *rate_idx >> 4;
423 	rbit = *rate_idx & 0xf;
424 
425 	if (ridx < 0 || ridx >= NL80211_VHT_NSS_MAX)
426 		return false;
427 
428 	/* See whether the selected rate or anything below it is allowed. */
429 	for (i = ridx; i >= 0; i--) {
430 		for (j = rbit; j >= 0; j--) {
431 			if (vht_mask[i] & BIT(j)) {
432 				*rate_idx = (i << 4) | j;
433 				return true;
434 			}
435 		}
436 		rbit = 15;
437 	}
438 
439 	/* Try to find a higher rate that would be allowed */
440 	ridx = (*rate_idx + 1) >> 4;
441 	rbit = (*rate_idx + 1) & 0xf;
442 
443 	for (i = ridx; i < NL80211_VHT_NSS_MAX; i++) {
444 		for (j = rbit; j < 16; j++) {
445 			if (vht_mask[i] & BIT(j)) {
446 				*rate_idx = (i << 4) | j;
447 				return true;
448 			}
449 		}
450 		rbit = 0;
451 	}
452 	return false;
453 }
454 
455 static void rate_idx_match_mask(s8 *rate_idx, u16 *rate_flags,
456 				struct ieee80211_supported_band *sband,
457 				enum nl80211_chan_width chan_width,
458 				u32 mask,
459 				u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN],
460 				u16 vht_mask[NL80211_VHT_NSS_MAX])
461 {
462 	if (*rate_flags & IEEE80211_TX_RC_VHT_MCS) {
463 		/* handle VHT rates */
464 		if (rate_idx_match_vht_mcs_mask(rate_idx, vht_mask))
465 			return;
466 
467 		*rate_idx = 0;
468 		/* keep protection flags */
469 		*rate_flags &= (IEEE80211_TX_RC_USE_RTS_CTS |
470 				IEEE80211_TX_RC_USE_CTS_PROTECT |
471 				IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
472 
473 		*rate_flags |= IEEE80211_TX_RC_MCS;
474 		if (chan_width == NL80211_CHAN_WIDTH_40)
475 			*rate_flags |= IEEE80211_TX_RC_40_MHZ_WIDTH;
476 
477 		if (rate_idx_match_mcs_mask(rate_idx, mcs_mask))
478 			return;
479 
480 		/* also try the legacy rates. */
481 		*rate_flags &= ~(IEEE80211_TX_RC_MCS |
482 				 IEEE80211_TX_RC_40_MHZ_WIDTH);
483 		if (rate_idx_match_legacy_mask(rate_idx, sband->n_bitrates,
484 					       mask))
485 			return;
486 	} else if (*rate_flags & IEEE80211_TX_RC_MCS) {
487 		/* handle HT rates */
488 		if (rate_idx_match_mcs_mask(rate_idx, mcs_mask))
489 			return;
490 
491 		/* also try the legacy rates. */
492 		*rate_idx = 0;
493 		/* keep protection flags */
494 		*rate_flags &= (IEEE80211_TX_RC_USE_RTS_CTS |
495 				IEEE80211_TX_RC_USE_CTS_PROTECT |
496 				IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
497 		if (rate_idx_match_legacy_mask(rate_idx, sband->n_bitrates,
498 					       mask))
499 			return;
500 	} else {
501 		/* handle legacy rates */
502 		if (rate_idx_match_legacy_mask(rate_idx, sband->n_bitrates,
503 					       mask))
504 			return;
505 
506 		/* if HT BSS, and we handle a data frame, also try HT rates */
507 		switch (chan_width) {
508 		case NL80211_CHAN_WIDTH_20_NOHT:
509 		case NL80211_CHAN_WIDTH_5:
510 		case NL80211_CHAN_WIDTH_10:
511 			return;
512 		default:
513 			break;
514 		}
515 
516 		*rate_idx = 0;
517 		/* keep protection flags */
518 		*rate_flags &= (IEEE80211_TX_RC_USE_RTS_CTS |
519 				IEEE80211_TX_RC_USE_CTS_PROTECT |
520 				IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
521 
522 		*rate_flags |= IEEE80211_TX_RC_MCS;
523 
524 		if (chan_width == NL80211_CHAN_WIDTH_40)
525 			*rate_flags |= IEEE80211_TX_RC_40_MHZ_WIDTH;
526 
527 		if (rate_idx_match_mcs_mask(rate_idx, mcs_mask))
528 			return;
529 	}
530 
531 	/*
532 	 * Uh.. No suitable rate exists. This should not really happen with
533 	 * sane TX rate mask configurations. However, should someone manage to
534 	 * configure supported rates and TX rate mask in incompatible way,
535 	 * allow the frame to be transmitted with whatever the rate control
536 	 * selected.
537 	 */
538 }
539 
540 static void rate_fixup_ratelist(struct ieee80211_vif *vif,
541 				struct ieee80211_supported_band *sband,
542 				struct ieee80211_tx_info *info,
543 				struct ieee80211_tx_rate *rates,
544 				int max_rates)
545 {
546 	struct ieee80211_rate *rate;
547 	bool inval = false;
548 	int i;
549 
550 	/*
551 	 * Set up the RTS/CTS rate as the fastest basic rate
552 	 * that is not faster than the data rate unless there
553 	 * is no basic rate slower than the data rate, in which
554 	 * case we pick the slowest basic rate
555 	 *
556 	 * XXX: Should this check all retry rates?
557 	 */
558 	if (!(rates[0].flags &
559 	      (IEEE80211_TX_RC_MCS | IEEE80211_TX_RC_VHT_MCS))) {
560 		u32 basic_rates = vif->bss_conf.basic_rates;
561 		s8 baserate = basic_rates ? ffs(basic_rates) - 1 : 0;
562 
563 		rate = &sband->bitrates[rates[0].idx];
564 
565 		for (i = 0; i < sband->n_bitrates; i++) {
566 			/* must be a basic rate */
567 			if (!(basic_rates & BIT(i)))
568 				continue;
569 			/* must not be faster than the data rate */
570 			if (sband->bitrates[i].bitrate > rate->bitrate)
571 				continue;
572 			/* maximum */
573 			if (sband->bitrates[baserate].bitrate <
574 			     sband->bitrates[i].bitrate)
575 				baserate = i;
576 		}
577 
578 		info->control.rts_cts_rate_idx = baserate;
579 	}
580 
581 	for (i = 0; i < max_rates; i++) {
582 		/*
583 		 * make sure there's no valid rate following
584 		 * an invalid one, just in case drivers don't
585 		 * take the API seriously to stop at -1.
586 		 */
587 		if (inval) {
588 			rates[i].idx = -1;
589 			continue;
590 		}
591 		if (rates[i].idx < 0) {
592 			inval = true;
593 			continue;
594 		}
595 
596 		/*
597 		 * For now assume MCS is already set up correctly, this
598 		 * needs to be fixed.
599 		 */
600 		if (rates[i].flags & IEEE80211_TX_RC_MCS) {
601 			WARN_ON(rates[i].idx > 76);
602 
603 			if (!(rates[i].flags & IEEE80211_TX_RC_USE_RTS_CTS) &&
604 			    info->control.use_cts_prot)
605 				rates[i].flags |=
606 					IEEE80211_TX_RC_USE_CTS_PROTECT;
607 			continue;
608 		}
609 
610 		if (rates[i].flags & IEEE80211_TX_RC_VHT_MCS) {
611 			WARN_ON(ieee80211_rate_get_vht_mcs(&rates[i]) > 9);
612 			continue;
613 		}
614 
615 		/* set up RTS protection if desired */
616 		if (info->control.use_rts) {
617 			rates[i].flags |= IEEE80211_TX_RC_USE_RTS_CTS;
618 			info->control.use_cts_prot = false;
619 		}
620 
621 		/* RC is busted */
622 		if (WARN_ON_ONCE(rates[i].idx >= sband->n_bitrates)) {
623 			rates[i].idx = -1;
624 			continue;
625 		}
626 
627 		rate = &sband->bitrates[rates[i].idx];
628 
629 		/* set up short preamble */
630 		if (info->control.short_preamble &&
631 		    rate->flags & IEEE80211_RATE_SHORT_PREAMBLE)
632 			rates[i].flags |= IEEE80211_TX_RC_USE_SHORT_PREAMBLE;
633 
634 		/* set up G protection */
635 		if (!(rates[i].flags & IEEE80211_TX_RC_USE_RTS_CTS) &&
636 		    info->control.use_cts_prot &&
637 		    rate->flags & IEEE80211_RATE_ERP_G)
638 			rates[i].flags |= IEEE80211_TX_RC_USE_CTS_PROTECT;
639 	}
640 }
641 
642 
643 static void rate_control_fill_sta_table(struct ieee80211_sta *sta,
644 					struct ieee80211_tx_info *info,
645 					struct ieee80211_tx_rate *rates,
646 					int max_rates)
647 {
648 	struct ieee80211_sta_rates *ratetbl = NULL;
649 	int i;
650 
651 	if (sta && !info->control.skip_table)
652 		ratetbl = rcu_dereference(sta->rates);
653 
654 	/* Fill remaining rate slots with data from the sta rate table. */
655 	max_rates = min_t(int, max_rates, IEEE80211_TX_RATE_TABLE_SIZE);
656 	for (i = 0; i < max_rates; i++) {
657 		if (i < ARRAY_SIZE(info->control.rates) &&
658 		    info->control.rates[i].idx >= 0 &&
659 		    info->control.rates[i].count) {
660 			if (rates != info->control.rates)
661 				rates[i] = info->control.rates[i];
662 		} else if (ratetbl) {
663 			rates[i].idx = ratetbl->rate[i].idx;
664 			rates[i].flags = ratetbl->rate[i].flags;
665 			if (info->control.use_rts)
666 				rates[i].count = ratetbl->rate[i].count_rts;
667 			else if (info->control.use_cts_prot)
668 				rates[i].count = ratetbl->rate[i].count_cts;
669 			else
670 				rates[i].count = ratetbl->rate[i].count;
671 		} else {
672 			rates[i].idx = -1;
673 			rates[i].count = 0;
674 		}
675 
676 		if (rates[i].idx < 0 || !rates[i].count)
677 			break;
678 	}
679 }
680 
681 static bool rate_control_cap_mask(struct ieee80211_sub_if_data *sdata,
682 				  struct ieee80211_supported_band *sband,
683 				  struct ieee80211_sta *sta, u32 *mask,
684 				  u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN],
685 				  u16 vht_mask[NL80211_VHT_NSS_MAX])
686 {
687 	u32 i, flags;
688 
689 	*mask = sdata->rc_rateidx_mask[sband->band];
690 	flags = ieee80211_chandef_rate_flags(&sdata->vif.bss_conf.chandef);
691 	for (i = 0; i < sband->n_bitrates; i++) {
692 		if ((flags & sband->bitrates[i].flags) != flags)
693 			*mask &= ~BIT(i);
694 	}
695 
696 	if (*mask == (1 << sband->n_bitrates) - 1 &&
697 	    !sdata->rc_has_mcs_mask[sband->band] &&
698 	    !sdata->rc_has_vht_mcs_mask[sband->band])
699 		return false;
700 
701 	if (sdata->rc_has_mcs_mask[sband->band])
702 		memcpy(mcs_mask, sdata->rc_rateidx_mcs_mask[sband->band],
703 		       IEEE80211_HT_MCS_MASK_LEN);
704 	else
705 		memset(mcs_mask, 0xff, IEEE80211_HT_MCS_MASK_LEN);
706 
707 	if (sdata->rc_has_vht_mcs_mask[sband->band])
708 		memcpy(vht_mask, sdata->rc_rateidx_vht_mcs_mask[sband->band],
709 		       sizeof(u16) * NL80211_VHT_NSS_MAX);
710 	else
711 		memset(vht_mask, 0xff, sizeof(u16) * NL80211_VHT_NSS_MAX);
712 
713 	if (sta) {
714 		__le16 sta_vht_cap;
715 		u16 sta_vht_mask[NL80211_VHT_NSS_MAX];
716 
717 		/* Filter out rates that the STA does not support */
718 		*mask &= sta->supp_rates[sband->band];
719 		for (i = 0; i < IEEE80211_HT_MCS_MASK_LEN; i++)
720 			mcs_mask[i] &= sta->ht_cap.mcs.rx_mask[i];
721 
722 		sta_vht_cap = sta->vht_cap.vht_mcs.rx_mcs_map;
723 		ieee80211_get_vht_mask_from_cap(sta_vht_cap, sta_vht_mask);
724 		for (i = 0; i < NL80211_VHT_NSS_MAX; i++)
725 			vht_mask[i] &= sta_vht_mask[i];
726 	}
727 
728 	return true;
729 }
730 
731 static void
732 rate_control_apply_mask_ratetbl(struct sta_info *sta,
733 				struct ieee80211_supported_band *sband,
734 				struct ieee80211_sta_rates *rates)
735 {
736 	int i;
737 	u32 mask;
738 	u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN];
739 	u16 vht_mask[NL80211_VHT_NSS_MAX];
740 	enum nl80211_chan_width chan_width;
741 
742 	if (!rate_control_cap_mask(sta->sdata, sband, &sta->sta, &mask,
743 				   mcs_mask, vht_mask))
744 		return;
745 
746 	chan_width = sta->sdata->vif.bss_conf.chandef.width;
747 	for (i = 0; i < IEEE80211_TX_RATE_TABLE_SIZE; i++) {
748 		if (rates->rate[i].idx < 0)
749 			break;
750 
751 		rate_idx_match_mask(&rates->rate[i].idx, &rates->rate[i].flags,
752 				    sband, chan_width, mask, mcs_mask,
753 				    vht_mask);
754 	}
755 }
756 
757 static void rate_control_apply_mask(struct ieee80211_sub_if_data *sdata,
758 				    struct ieee80211_sta *sta,
759 				    struct ieee80211_supported_band *sband,
760 				    struct ieee80211_tx_rate *rates,
761 				    int max_rates)
762 {
763 	enum nl80211_chan_width chan_width;
764 	u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN];
765 	u32 mask;
766 	u16 rate_flags, vht_mask[NL80211_VHT_NSS_MAX];
767 	int i;
768 
769 	/*
770 	 * Try to enforce the rateidx mask the user wanted. skip this if the
771 	 * default mask (allow all rates) is used to save some processing for
772 	 * the common case.
773 	 */
774 	if (!rate_control_cap_mask(sdata, sband, sta, &mask, mcs_mask,
775 				   vht_mask))
776 		return;
777 
778 	/*
779 	 * Make sure the rate index selected for each TX rate is
780 	 * included in the configured mask and change the rate indexes
781 	 * if needed.
782 	 */
783 	chan_width = sdata->vif.bss_conf.chandef.width;
784 	for (i = 0; i < max_rates; i++) {
785 		/* Skip invalid rates */
786 		if (rates[i].idx < 0)
787 			break;
788 
789 		rate_flags = rates[i].flags;
790 		rate_idx_match_mask(&rates[i].idx, &rate_flags, sband,
791 				    chan_width, mask, mcs_mask, vht_mask);
792 		rates[i].flags = rate_flags;
793 	}
794 }
795 
796 void ieee80211_get_tx_rates(struct ieee80211_vif *vif,
797 			    struct ieee80211_sta *sta,
798 			    struct sk_buff *skb,
799 			    struct ieee80211_tx_rate *dest,
800 			    int max_rates)
801 {
802 	struct ieee80211_sub_if_data *sdata;
803 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
804 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
805 	struct ieee80211_supported_band *sband;
806 
807 	rate_control_fill_sta_table(sta, info, dest, max_rates);
808 
809 	if (!vif)
810 		return;
811 
812 	sdata = vif_to_sdata(vif);
813 	sband = sdata->local->hw.wiphy->bands[info->band];
814 
815 	if (ieee80211_is_data(hdr->frame_control))
816 		rate_control_apply_mask(sdata, sta, sband, dest, max_rates);
817 
818 	if (dest[0].idx < 0)
819 		__rate_control_send_low(&sdata->local->hw, sband, sta, info,
820 					sdata->rc_rateidx_mask[info->band]);
821 
822 	if (sta)
823 		rate_fixup_ratelist(vif, sband, info, dest, max_rates);
824 }
825 EXPORT_SYMBOL(ieee80211_get_tx_rates);
826 
827 void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
828 			   struct sta_info *sta,
829 			   struct ieee80211_tx_rate_control *txrc)
830 {
831 	struct rate_control_ref *ref = sdata->local->rate_ctrl;
832 	void *priv_sta = NULL;
833 	struct ieee80211_sta *ista = NULL;
834 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
835 	int i;
836 
837 	if (sta && test_sta_flag(sta, WLAN_STA_RATE_CONTROL)) {
838 		ista = &sta->sta;
839 		priv_sta = sta->rate_ctrl_priv;
840 	}
841 
842 	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
843 		info->control.rates[i].idx = -1;
844 		info->control.rates[i].flags = 0;
845 		info->control.rates[i].count = 0;
846 	}
847 
848 	if (ieee80211_hw_check(&sdata->local->hw, HAS_RATE_CONTROL))
849 		return;
850 
851 	if (ista) {
852 		spin_lock_bh(&sta->rate_ctrl_lock);
853 		ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
854 		spin_unlock_bh(&sta->rate_ctrl_lock);
855 	} else {
856 		ref->ops->get_rate(ref->priv, NULL, NULL, txrc);
857 	}
858 
859 	if (ieee80211_hw_check(&sdata->local->hw, SUPPORTS_RC_TABLE))
860 		return;
861 
862 	ieee80211_get_tx_rates(&sdata->vif, ista, txrc->skb,
863 			       info->control.rates,
864 			       ARRAY_SIZE(info->control.rates));
865 }
866 
867 int rate_control_set_rates(struct ieee80211_hw *hw,
868 			   struct ieee80211_sta *pubsta,
869 			   struct ieee80211_sta_rates *rates)
870 {
871 	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
872 	struct ieee80211_sta_rates *old;
873 	struct ieee80211_supported_band *sband;
874 
875 	sband = hw->wiphy->bands[ieee80211_get_sdata_band(sta->sdata)];
876 	rate_control_apply_mask_ratetbl(sta, sband, rates);
877 	/*
878 	 * mac80211 guarantees that this function will not be called
879 	 * concurrently, so the following RCU access is safe, even without
880 	 * extra locking. This can not be checked easily, so we just set
881 	 * the condition to true.
882 	 */
883 	old = rcu_dereference_protected(pubsta->rates, true);
884 	rcu_assign_pointer(pubsta->rates, rates);
885 	if (old)
886 		kfree_rcu(old, rcu_head);
887 
888 	drv_sta_rate_tbl_update(hw_to_local(hw), sta->sdata, pubsta);
889 
890 	return 0;
891 }
892 EXPORT_SYMBOL(rate_control_set_rates);
893 
894 int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
895 				 const char *name)
896 {
897 	struct rate_control_ref *ref;
898 
899 	ASSERT_RTNL();
900 
901 	if (local->open_count)
902 		return -EBUSY;
903 
904 	if (ieee80211_hw_check(&local->hw, HAS_RATE_CONTROL)) {
905 		if (WARN_ON(!local->ops->set_rts_threshold))
906 			return -EINVAL;
907 		return 0;
908 	}
909 
910 	ref = rate_control_alloc(name, local);
911 	if (!ref) {
912 		wiphy_warn(local->hw.wiphy,
913 			   "Failed to select rate control algorithm\n");
914 		return -ENOENT;
915 	}
916 
917 	WARN_ON(local->rate_ctrl);
918 	local->rate_ctrl = ref;
919 
920 	wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
921 		    ref->ops->name);
922 
923 	return 0;
924 }
925 
926 void rate_control_deinitialize(struct ieee80211_local *local)
927 {
928 	struct rate_control_ref *ref;
929 
930 	ref = local->rate_ctrl;
931 
932 	if (!ref)
933 		return;
934 
935 	local->rate_ctrl = NULL;
936 	rate_control_free(ref);
937 }
938 
939