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Linux/net/mac80211/rc80211_minstrel.c

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  1 /*
  2  * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License version 2 as
  6  * published by the Free Software Foundation.
  7  *
  8  * Based on minstrel.c:
  9  *   Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
 10  *   Sponsored by Indranet Technologies Ltd
 11  *
 12  * Based on sample.c:
 13  *   Copyright (c) 2005 John Bicket
 14  *   All rights reserved.
 15  *
 16  *   Redistribution and use in source and binary forms, with or without
 17  *   modification, are permitted provided that the following conditions
 18  *   are met:
 19  *   1. Redistributions of source code must retain the above copyright
 20  *      notice, this list of conditions and the following disclaimer,
 21  *      without modification.
 22  *   2. Redistributions in binary form must reproduce at minimum a disclaimer
 23  *      similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
 24  *      redistribution must be conditioned upon including a substantially
 25  *      similar Disclaimer requirement for further binary redistribution.
 26  *   3. Neither the names of the above-listed copyright holders nor the names
 27  *      of any contributors may be used to endorse or promote products derived
 28  *      from this software without specific prior written permission.
 29  *
 30  *   Alternatively, this software may be distributed under the terms of the
 31  *   GNU General Public License ("GPL") version 2 as published by the Free
 32  *   Software Foundation.
 33  *
 34  *   NO WARRANTY
 35  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 36  *   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 37  *   LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
 38  *   AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 39  *   THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
 40  *   OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 41  *   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 42  *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 43  *   IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 44  *   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 45  *   THE POSSIBILITY OF SUCH DAMAGES.
 46  */
 47 #include <linux/netdevice.h>
 48 #include <linux/types.h>
 49 #include <linux/skbuff.h>
 50 #include <linux/debugfs.h>
 51 #include <linux/random.h>
 52 #include <linux/ieee80211.h>
 53 #include <linux/slab.h>
 54 #include <net/mac80211.h>
 55 #include "rate.h"
 56 #include "rc80211_minstrel.h"
 57 
 58 #define SAMPLE_TBL(_mi, _idx, _col) \
 59                 _mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]
 60 
 61 /* convert mac80211 rate index to local array index */
 62 static inline int
 63 rix_to_ndx(struct minstrel_sta_info *mi, int rix)
 64 {
 65         int i = rix;
 66         for (i = rix; i >= 0; i--)
 67                 if (mi->r[i].rix == rix)
 68                         break;
 69         return i;
 70 }
 71 
 72 /* return current EMWA throughput */
 73 int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma)
 74 {
 75         int usecs;
 76 
 77         usecs = mr->perfect_tx_time;
 78         if (!usecs)
 79                 usecs = 1000000;
 80 
 81         /* reset thr. below 10% success */
 82         if (mr->stats.prob_ewma < MINSTREL_FRAC(10, 100))
 83                 return 0;
 84 
 85         if (prob_ewma > MINSTREL_FRAC(90, 100))
 86                 return MINSTREL_TRUNC(100000 * (MINSTREL_FRAC(90, 100) / usecs));
 87         else
 88                 return MINSTREL_TRUNC(100000 * (prob_ewma / usecs));
 89 }
 90 
 91 /* find & sort topmost throughput rates */
 92 static inline void
 93 minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list)
 94 {
 95         int j;
 96         struct minstrel_rate_stats *tmp_mrs;
 97         struct minstrel_rate_stats *cur_mrs = &mi->r[i].stats;
 98 
 99         for (j = MAX_THR_RATES; j > 0; --j) {
100                 tmp_mrs = &mi->r[tp_list[j - 1]].stats;
101                 if (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) <=
102                     minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma))
103                         break;
104         }
105 
106         if (j < MAX_THR_RATES - 1)
107                 memmove(&tp_list[j + 1], &tp_list[j], MAX_THR_RATES - (j + 1));
108         if (j < MAX_THR_RATES)
109                 tp_list[j] = i;
110 }
111 
112 static void
113 minstrel_set_rate(struct minstrel_sta_info *mi, struct ieee80211_sta_rates *ratetbl,
114                   int offset, int idx)
115 {
116         struct minstrel_rate *r = &mi->r[idx];
117 
118         ratetbl->rate[offset].idx = r->rix;
119         ratetbl->rate[offset].count = r->adjusted_retry_count;
120         ratetbl->rate[offset].count_cts = r->retry_count_cts;
121         ratetbl->rate[offset].count_rts = r->stats.retry_count_rtscts;
122 }
123 
124 static void
125 minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
126 {
127         struct ieee80211_sta_rates *ratetbl;
128         int i = 0;
129 
130         ratetbl = kzalloc(sizeof(*ratetbl), GFP_ATOMIC);
131         if (!ratetbl)
132                 return;
133 
134         /* Start with max_tp_rate */
135         minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[0]);
136 
137         if (mp->hw->max_rates >= 3) {
138                 /* At least 3 tx rates supported, use max_tp_rate2 next */
139                 minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[1]);
140         }
141 
142         if (mp->hw->max_rates >= 2) {
143                 /* At least 2 tx rates supported, use max_prob_rate next */
144                 minstrel_set_rate(mi, ratetbl, i++, mi->max_prob_rate);
145         }
146 
147         /* Use lowest rate last */
148         ratetbl->rate[i].idx = mi->lowest_rix;
149         ratetbl->rate[i].count = mp->max_retry;
150         ratetbl->rate[i].count_cts = mp->max_retry;
151         ratetbl->rate[i].count_rts = mp->max_retry;
152 
153         rate_control_set_rates(mp->hw, mi->sta, ratetbl);
154 }
155 
156 /*
157 * Recalculate statistics and counters of a given rate
158 */
159 void
160 minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
161 {
162         unsigned int cur_prob;
163 
164         if (unlikely(mrs->attempts > 0)) {
165                 mrs->sample_skipped = 0;
166                 cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
167                 if (unlikely(!mrs->att_hist)) {
168                         mrs->prob_ewma = cur_prob;
169                 } else {
170                         /* update exponential weighted moving variance */
171                         mrs->prob_ewmv = minstrel_ewmv(mrs->prob_ewmv,
172                                                         cur_prob,
173                                                         mrs->prob_ewma,
174                                                         EWMA_LEVEL);
175 
176                         /*update exponential weighted moving avarage */
177                         mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
178                                                        cur_prob,
179                                                        EWMA_LEVEL);
180                 }
181                 mrs->att_hist += mrs->attempts;
182                 mrs->succ_hist += mrs->success;
183         } else {
184                 mrs->sample_skipped++;
185         }
186 
187         mrs->last_success = mrs->success;
188         mrs->last_attempts = mrs->attempts;
189         mrs->success = 0;
190         mrs->attempts = 0;
191 }
192 
193 static void
194 minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
195 {
196         u8 tmp_tp_rate[MAX_THR_RATES];
197         u8 tmp_prob_rate = 0;
198         int i, tmp_cur_tp, tmp_prob_tp;
199 
200         for (i = 0; i < MAX_THR_RATES; i++)
201             tmp_tp_rate[i] = 0;
202 
203         for (i = 0; i < mi->n_rates; i++) {
204                 struct minstrel_rate *mr = &mi->r[i];
205                 struct minstrel_rate_stats *mrs = &mi->r[i].stats;
206                 struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;
207 
208                 /* Update statistics of success probability per rate */
209                 minstrel_calc_rate_stats(mrs);
210 
211                 /* Sample less often below the 10% chance of success.
212                  * Sample less often above the 95% chance of success. */
213                 if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
214                     mrs->prob_ewma < MINSTREL_FRAC(10, 100)) {
215                         mr->adjusted_retry_count = mrs->retry_count >> 1;
216                         if (mr->adjusted_retry_count > 2)
217                                 mr->adjusted_retry_count = 2;
218                         mr->sample_limit = 4;
219                 } else {
220                         mr->sample_limit = -1;
221                         mr->adjusted_retry_count = mrs->retry_count;
222                 }
223                 if (!mr->adjusted_retry_count)
224                         mr->adjusted_retry_count = 2;
225 
226                 minstrel_sort_best_tp_rates(mi, i, tmp_tp_rate);
227 
228                 /* To determine the most robust rate (max_prob_rate) used at
229                  * 3rd mmr stage we distinct between two cases:
230                  * (1) if any success probabilitiy >= 95%, out of those rates
231                  * choose the maximum throughput rate as max_prob_rate
232                  * (2) if all success probabilities < 95%, the rate with
233                  * highest success probability is chosen as max_prob_rate */
234                 if (mrs->prob_ewma >= MINSTREL_FRAC(95, 100)) {
235                         tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_ewma);
236                         tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate],
237                                                           tmp_mrs->prob_ewma);
238                         if (tmp_cur_tp >= tmp_prob_tp)
239                                 tmp_prob_rate = i;
240                 } else {
241                         if (mrs->prob_ewma >= tmp_mrs->prob_ewma)
242                                 tmp_prob_rate = i;
243                 }
244         }
245 
246         /* Assign the new rate set */
247         memcpy(mi->max_tp_rate, tmp_tp_rate, sizeof(mi->max_tp_rate));
248         mi->max_prob_rate = tmp_prob_rate;
249 
250 #ifdef CONFIG_MAC80211_DEBUGFS
251         /* use fixed index if set */
252         if (mp->fixed_rate_idx != -1) {
253                 mi->max_tp_rate[0] = mp->fixed_rate_idx;
254                 mi->max_tp_rate[1] = mp->fixed_rate_idx;
255                 mi->max_prob_rate = mp->fixed_rate_idx;
256         }
257 #endif
258 
259         /* Reset update timer */
260         mi->last_stats_update = jiffies;
261 
262         minstrel_update_rates(mp, mi);
263 }
264 
265 static void
266 minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
267                    void *priv_sta, struct ieee80211_tx_status *st)
268 {
269         struct ieee80211_tx_info *info = st->info;
270         struct minstrel_priv *mp = priv;
271         struct minstrel_sta_info *mi = priv_sta;
272         struct ieee80211_tx_rate *ar = info->status.rates;
273         int i, ndx;
274         int success;
275 
276         success = !!(info->flags & IEEE80211_TX_STAT_ACK);
277 
278         for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
279                 if (ar[i].idx < 0)
280                         break;
281 
282                 ndx = rix_to_ndx(mi, ar[i].idx);
283                 if (ndx < 0)
284                         continue;
285 
286                 mi->r[ndx].stats.attempts += ar[i].count;
287 
288                 if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
289                         mi->r[ndx].stats.success += success;
290         }
291 
292         if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
293                 mi->sample_packets++;
294 
295         if (mi->sample_deferred > 0)
296                 mi->sample_deferred--;
297 
298         if (time_after(jiffies, mi->last_stats_update +
299                                 (mp->update_interval * HZ) / 1000))
300                 minstrel_update_stats(mp, mi);
301 }
302 
303 
304 static inline unsigned int
305 minstrel_get_retry_count(struct minstrel_rate *mr,
306                          struct ieee80211_tx_info *info)
307 {
308         u8 retry = mr->adjusted_retry_count;
309 
310         if (info->control.use_rts)
311                 retry = max_t(u8, 2, min(mr->stats.retry_count_rtscts, retry));
312         else if (info->control.use_cts_prot)
313                 retry = max_t(u8, 2, min(mr->retry_count_cts, retry));
314         return retry;
315 }
316 
317 
318 static int
319 minstrel_get_next_sample(struct minstrel_sta_info *mi)
320 {
321         unsigned int sample_ndx;
322         sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column);
323         mi->sample_row++;
324         if ((int) mi->sample_row >= mi->n_rates) {
325                 mi->sample_row = 0;
326                 mi->sample_column++;
327                 if (mi->sample_column >= SAMPLE_COLUMNS)
328                         mi->sample_column = 0;
329         }
330         return sample_ndx;
331 }
332 
333 static void
334 minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
335                   void *priv_sta, struct ieee80211_tx_rate_control *txrc)
336 {
337         struct sk_buff *skb = txrc->skb;
338         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
339         struct minstrel_sta_info *mi = priv_sta;
340         struct minstrel_priv *mp = priv;
341         struct ieee80211_tx_rate *rate = &info->control.rates[0];
342         struct minstrel_rate *msr, *mr;
343         unsigned int ndx;
344         bool mrr_capable;
345         bool prev_sample;
346         int delta;
347         int sampling_ratio;
348 
349         /* management/no-ack frames do not use rate control */
350         if (rate_control_send_low(sta, priv_sta, txrc))
351                 return;
352 
353         /* check multi-rate-retry capabilities & adjust lookaround_rate */
354         mrr_capable = mp->has_mrr &&
355                       !txrc->rts &&
356                       !txrc->bss_conf->use_cts_prot;
357         if (mrr_capable)
358                 sampling_ratio = mp->lookaround_rate_mrr;
359         else
360                 sampling_ratio = mp->lookaround_rate;
361 
362         /* increase sum packet counter */
363         mi->total_packets++;
364 
365 #ifdef CONFIG_MAC80211_DEBUGFS
366         if (mp->fixed_rate_idx != -1)
367                 return;
368 #endif
369 
370         /* Don't use EAPOL frames for sampling on non-mrr hw */
371         if (mp->hw->max_rates == 1 &&
372             (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
373                 return;
374 
375         delta = (mi->total_packets * sampling_ratio / 100) -
376                         (mi->sample_packets + mi->sample_deferred / 2);
377 
378         /* delta < 0: no sampling required */
379         prev_sample = mi->prev_sample;
380         mi->prev_sample = false;
381         if (delta < 0 || (!mrr_capable && prev_sample))
382                 return;
383 
384         if (mi->total_packets >= 10000) {
385                 mi->sample_deferred = 0;
386                 mi->sample_packets = 0;
387                 mi->total_packets = 0;
388         } else if (delta > mi->n_rates * 2) {
389                 /* With multi-rate retry, not every planned sample
390                  * attempt actually gets used, due to the way the retry
391                  * chain is set up - [max_tp,sample,prob,lowest] for
392                  * sample_rate < max_tp.
393                  *
394                  * If there's too much sampling backlog and the link
395                  * starts getting worse, minstrel would start bursting
396                  * out lots of sampling frames, which would result
397                  * in a large throughput loss. */
398                 mi->sample_packets += (delta - mi->n_rates * 2);
399         }
400 
401         /* get next random rate sample */
402         ndx = minstrel_get_next_sample(mi);
403         msr = &mi->r[ndx];
404         mr = &mi->r[mi->max_tp_rate[0]];
405 
406         /* Decide if direct ( 1st mrr stage) or indirect (2nd mrr stage)
407          * rate sampling method should be used.
408          * Respect such rates that are not sampled for 20 interations.
409          */
410         if (mrr_capable &&
411             msr->perfect_tx_time > mr->perfect_tx_time &&
412             msr->stats.sample_skipped < 20) {
413                 /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
414                  * packets that have the sampling rate deferred to the
415                  * second MRR stage. Increase the sample counter only
416                  * if the deferred sample rate was actually used.
417                  * Use the sample_deferred counter to make sure that
418                  * the sampling is not done in large bursts */
419                 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
420                 rate++;
421                 mi->sample_deferred++;
422         } else {
423                 if (!msr->sample_limit)
424                         return;
425 
426                 mi->sample_packets++;
427                 if (msr->sample_limit > 0)
428                         msr->sample_limit--;
429         }
430 
431         /* If we're not using MRR and the sampling rate already
432          * has a probability of >95%, we shouldn't be attempting
433          * to use it, as this only wastes precious airtime */
434         if (!mrr_capable &&
435            (mi->r[ndx].stats.prob_ewma > MINSTREL_FRAC(95, 100)))
436                 return;
437 
438         mi->prev_sample = true;
439 
440         rate->idx = mi->r[ndx].rix;
441         rate->count = minstrel_get_retry_count(&mi->r[ndx], info);
442 }
443 
444 
445 static void
446 calc_rate_durations(enum nl80211_band band,
447                     struct minstrel_rate *d,
448                     struct ieee80211_rate *rate,
449                     struct cfg80211_chan_def *chandef)
450 {
451         int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
452         int shift = ieee80211_chandef_get_shift(chandef);
453 
454         d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
455                         DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
456                         shift);
457         d->ack_time = ieee80211_frame_duration(band, 10,
458                         DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
459                         shift);
460 }
461 
462 static void
463 init_sample_table(struct minstrel_sta_info *mi)
464 {
465         unsigned int i, col, new_idx;
466         u8 rnd[8];
467 
468         mi->sample_column = 0;
469         mi->sample_row = 0;
470         memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates);
471 
472         for (col = 0; col < SAMPLE_COLUMNS; col++) {
473                 prandom_bytes(rnd, sizeof(rnd));
474                 for (i = 0; i < mi->n_rates; i++) {
475                         new_idx = (i + rnd[i & 7]) % mi->n_rates;
476                         while (SAMPLE_TBL(mi, new_idx, col) != 0xff)
477                                 new_idx = (new_idx + 1) % mi->n_rates;
478 
479                         SAMPLE_TBL(mi, new_idx, col) = i;
480                 }
481         }
482 }
483 
484 static void
485 minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
486                    struct cfg80211_chan_def *chandef,
487                    struct ieee80211_sta *sta, void *priv_sta)
488 {
489         struct minstrel_sta_info *mi = priv_sta;
490         struct minstrel_priv *mp = priv;
491         struct ieee80211_rate *ctl_rate;
492         unsigned int i, n = 0;
493         unsigned int t_slot = 9; /* FIXME: get real slot time */
494         u32 rate_flags;
495 
496         mi->sta = sta;
497         mi->lowest_rix = rate_lowest_index(sband, sta);
498         ctl_rate = &sband->bitrates[mi->lowest_rix];
499         mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10,
500                                 ctl_rate->bitrate,
501                                 !!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1,
502                                 ieee80211_chandef_get_shift(chandef));
503 
504         rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
505         memset(mi->max_tp_rate, 0, sizeof(mi->max_tp_rate));
506         mi->max_prob_rate = 0;
507 
508         for (i = 0; i < sband->n_bitrates; i++) {
509                 struct minstrel_rate *mr = &mi->r[n];
510                 struct minstrel_rate_stats *mrs = &mi->r[n].stats;
511                 unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
512                 unsigned int tx_time_single;
513                 unsigned int cw = mp->cw_min;
514                 int shift;
515 
516                 if (!rate_supported(sta, sband->band, i))
517                         continue;
518                 if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
519                         continue;
520 
521                 n++;
522                 memset(mr, 0, sizeof(*mr));
523                 memset(mrs, 0, sizeof(*mrs));
524 
525                 mr->rix = i;
526                 shift = ieee80211_chandef_get_shift(chandef);
527                 mr->bitrate = DIV_ROUND_UP(sband->bitrates[i].bitrate,
528                                            (1 << shift) * 5);
529                 calc_rate_durations(sband->band, mr, &sband->bitrates[i],
530                                     chandef);
531 
532                 /* calculate maximum number of retransmissions before
533                  * fallback (based on maximum segment size) */
534                 mr->sample_limit = -1;
535                 mrs->retry_count = 1;
536                 mr->retry_count_cts = 1;
537                 mrs->retry_count_rtscts = 1;
538                 tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
539                 do {
540                         /* add one retransmission */
541                         tx_time_single = mr->ack_time + mr->perfect_tx_time;
542 
543                         /* contention window */
544                         tx_time_single += (t_slot * cw) >> 1;
545                         cw = min((cw << 1) | 1, mp->cw_max);
546 
547                         tx_time += tx_time_single;
548                         tx_time_cts += tx_time_single + mi->sp_ack_dur;
549                         tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
550                         if ((tx_time_cts < mp->segment_size) &&
551                                 (mr->retry_count_cts < mp->max_retry))
552                                 mr->retry_count_cts++;
553                         if ((tx_time_rtscts < mp->segment_size) &&
554                                 (mrs->retry_count_rtscts < mp->max_retry))
555                                 mrs->retry_count_rtscts++;
556                 } while ((tx_time < mp->segment_size) &&
557                                 (++mr->stats.retry_count < mp->max_retry));
558                 mr->adjusted_retry_count = mrs->retry_count;
559                 if (!(sband->bitrates[i].flags & IEEE80211_RATE_ERP_G))
560                         mr->retry_count_cts = mrs->retry_count;
561         }
562 
563         for (i = n; i < sband->n_bitrates; i++) {
564                 struct minstrel_rate *mr = &mi->r[i];
565                 mr->rix = -1;
566         }
567 
568         mi->n_rates = n;
569         mi->last_stats_update = jiffies;
570 
571         init_sample_table(mi);
572         minstrel_update_rates(mp, mi);
573 }
574 
575 static void *
576 minstrel_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
577 {
578         struct ieee80211_supported_band *sband;
579         struct minstrel_sta_info *mi;
580         struct minstrel_priv *mp = priv;
581         struct ieee80211_hw *hw = mp->hw;
582         int max_rates = 0;
583         int i;
584 
585         mi = kzalloc(sizeof(struct minstrel_sta_info), gfp);
586         if (!mi)
587                 return NULL;
588 
589         for (i = 0; i < NUM_NL80211_BANDS; i++) {
590                 sband = hw->wiphy->bands[i];
591                 if (sband && sband->n_bitrates > max_rates)
592                         max_rates = sband->n_bitrates;
593         }
594 
595         mi->r = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
596         if (!mi->r)
597                 goto error;
598 
599         mi->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
600         if (!mi->sample_table)
601                 goto error1;
602 
603         mi->last_stats_update = jiffies;
604         return mi;
605 
606 error1:
607         kfree(mi->r);
608 error:
609         kfree(mi);
610         return NULL;
611 }
612 
613 static void
614 minstrel_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
615 {
616         struct minstrel_sta_info *mi = priv_sta;
617 
618         kfree(mi->sample_table);
619         kfree(mi->r);
620         kfree(mi);
621 }
622 
623 static void
624 minstrel_init_cck_rates(struct minstrel_priv *mp)
625 {
626         static const int bitrates[4] = { 10, 20, 55, 110 };
627         struct ieee80211_supported_band *sband;
628         u32 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
629         int i, j;
630 
631         sband = mp->hw->wiphy->bands[NL80211_BAND_2GHZ];
632         if (!sband)
633                 return;
634 
635         for (i = 0, j = 0; i < sband->n_bitrates; i++) {
636                 struct ieee80211_rate *rate = &sband->bitrates[i];
637 
638                 if (rate->flags & IEEE80211_RATE_ERP_G)
639                         continue;
640 
641                 if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
642                         continue;
643 
644                 for (j = 0; j < ARRAY_SIZE(bitrates); j++) {
645                         if (rate->bitrate != bitrates[j])
646                                 continue;
647 
648                         mp->cck_rates[j] = i;
649                         break;
650                 }
651         }
652 }
653 
654 static void *
655 minstrel_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
656 {
657         struct minstrel_priv *mp;
658 
659         mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
660         if (!mp)
661                 return NULL;
662 
663         /* contention window settings
664          * Just an approximation. Using the per-queue values would complicate
665          * the calculations and is probably unnecessary */
666         mp->cw_min = 15;
667         mp->cw_max = 1023;
668 
669         /* number of packets (in %) to use for sampling other rates
670          * sample less often for non-mrr packets, because the overhead
671          * is much higher than with mrr */
672         mp->lookaround_rate = 5;
673         mp->lookaround_rate_mrr = 10;
674 
675         /* maximum time that the hw is allowed to stay in one MRR segment */
676         mp->segment_size = 6000;
677 
678         if (hw->max_rate_tries > 0)
679                 mp->max_retry = hw->max_rate_tries;
680         else
681                 /* safe default, does not necessarily have to match hw properties */
682                 mp->max_retry = 7;
683 
684         if (hw->max_rates >= 4)
685                 mp->has_mrr = true;
686 
687         mp->hw = hw;
688         mp->update_interval = 100;
689 
690 #ifdef CONFIG_MAC80211_DEBUGFS
691         mp->fixed_rate_idx = (u32) -1;
692         mp->dbg_fixed_rate = debugfs_create_u32("fixed_rate_idx",
693                         S_IRUGO | S_IWUGO, debugfsdir, &mp->fixed_rate_idx);
694 #endif
695 
696         minstrel_init_cck_rates(mp);
697 
698         return mp;
699 }
700 
701 static void
702 minstrel_free(void *priv)
703 {
704 #ifdef CONFIG_MAC80211_DEBUGFS
705         debugfs_remove(((struct minstrel_priv *)priv)->dbg_fixed_rate);
706 #endif
707         kfree(priv);
708 }
709 
710 static u32 minstrel_get_expected_throughput(void *priv_sta)
711 {
712         struct minstrel_sta_info *mi = priv_sta;
713         struct minstrel_rate_stats *tmp_mrs;
714         int idx = mi->max_tp_rate[0];
715         int tmp_cur_tp;
716 
717         /* convert pkt per sec in kbps (1200 is the average pkt size used for
718          * computing cur_tp
719          */
720         tmp_mrs = &mi->r[idx].stats;
721         tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_ewma) * 10;
722         tmp_cur_tp = tmp_cur_tp * 1200 * 8 / 1024;
723 
724         return tmp_cur_tp;
725 }
726 
727 const struct rate_control_ops mac80211_minstrel = {
728         .name = "minstrel",
729         .tx_status_ext = minstrel_tx_status,
730         .get_rate = minstrel_get_rate,
731         .rate_init = minstrel_rate_init,
732         .alloc = minstrel_alloc,
733         .free = minstrel_free,
734         .alloc_sta = minstrel_alloc_sta,
735         .free_sta = minstrel_free_sta,
736 #ifdef CONFIG_MAC80211_DEBUGFS
737         .add_sta_debugfs = minstrel_add_sta_debugfs,
738         .remove_sta_debugfs = minstrel_remove_sta_debugfs,
739 #endif
740         .get_expected_throughput = minstrel_get_expected_throughput,
741 };
742 
743 int __init
744 rc80211_minstrel_init(void)
745 {
746         return ieee80211_rate_control_register(&mac80211_minstrel);
747 }
748 
749 void
750 rc80211_minstrel_exit(void)
751 {
752         ieee80211_rate_control_unregister(&mac80211_minstrel);
753 }
754 
755 

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