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TOMOYO Linux Cross Reference
Linux/net/mac80211/rc80211_minstrel.c

Version: ~ [ linux-5.6 ] ~ [ linux-5.5.13 ] ~ [ linux-5.4.28 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.113 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.174 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.217 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.217 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.82 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 avarage */
171                         mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
172                                                        cur_prob,
173                                                        EWMA_LEVEL);
174                 }
175                 mrs->att_hist += mrs->attempts;
176                 mrs->succ_hist += mrs->success;
177         } else {
178                 mrs->sample_skipped++;
179         }
180 
181         mrs->last_success = mrs->success;
182         mrs->last_attempts = mrs->attempts;
183         mrs->success = 0;
184         mrs->attempts = 0;
185 }
186 
187 static void
188 minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
189 {
190         u8 tmp_tp_rate[MAX_THR_RATES];
191         u8 tmp_prob_rate = 0;
192         int i, tmp_cur_tp, tmp_prob_tp;
193 
194         for (i = 0; i < MAX_THR_RATES; i++)
195             tmp_tp_rate[i] = 0;
196 
197         for (i = 0; i < mi->n_rates; i++) {
198                 struct minstrel_rate *mr = &mi->r[i];
199                 struct minstrel_rate_stats *mrs = &mi->r[i].stats;
200                 struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;
201 
202                 /* Update statistics of success probability per rate */
203                 minstrel_calc_rate_stats(mrs);
204 
205                 /* Sample less often below the 10% chance of success.
206                  * Sample less often above the 95% chance of success. */
207                 if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
208                     mrs->prob_ewma < MINSTREL_FRAC(10, 100)) {
209                         mr->adjusted_retry_count = mrs->retry_count >> 1;
210                         if (mr->adjusted_retry_count > 2)
211                                 mr->adjusted_retry_count = 2;
212                         mr->sample_limit = 4;
213                 } else {
214                         mr->sample_limit = -1;
215                         mr->adjusted_retry_count = mrs->retry_count;
216                 }
217                 if (!mr->adjusted_retry_count)
218                         mr->adjusted_retry_count = 2;
219 
220                 minstrel_sort_best_tp_rates(mi, i, tmp_tp_rate);
221 
222                 /* To determine the most robust rate (max_prob_rate) used at
223                  * 3rd mmr stage we distinct between two cases:
224                  * (1) if any success probabilitiy >= 95%, out of those rates
225                  * choose the maximum throughput rate as max_prob_rate
226                  * (2) if all success probabilities < 95%, the rate with
227                  * highest success probability is chosen as max_prob_rate */
228                 if (mrs->prob_ewma >= MINSTREL_FRAC(95, 100)) {
229                         tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_ewma);
230                         tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate],
231                                                           tmp_mrs->prob_ewma);
232                         if (tmp_cur_tp >= tmp_prob_tp)
233                                 tmp_prob_rate = i;
234                 } else {
235                         if (mrs->prob_ewma >= tmp_mrs->prob_ewma)
236                                 tmp_prob_rate = i;
237                 }
238         }
239 
240         /* Assign the new rate set */
241         memcpy(mi->max_tp_rate, tmp_tp_rate, sizeof(mi->max_tp_rate));
242         mi->max_prob_rate = tmp_prob_rate;
243 
244 #ifdef CONFIG_MAC80211_DEBUGFS
245         /* use fixed index if set */
246         if (mp->fixed_rate_idx != -1) {
247                 mi->max_tp_rate[0] = mp->fixed_rate_idx;
248                 mi->max_tp_rate[1] = mp->fixed_rate_idx;
249                 mi->max_prob_rate = mp->fixed_rate_idx;
250         }
251 #endif
252 
253         /* Reset update timer */
254         mi->last_stats_update = jiffies;
255 
256         minstrel_update_rates(mp, mi);
257 }
258 
259 static void
260 minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
261                    void *priv_sta, struct ieee80211_tx_status *st)
262 {
263         struct ieee80211_tx_info *info = st->info;
264         struct minstrel_priv *mp = priv;
265         struct minstrel_sta_info *mi = priv_sta;
266         struct ieee80211_tx_rate *ar = info->status.rates;
267         int i, ndx;
268         int success;
269 
270         success = !!(info->flags & IEEE80211_TX_STAT_ACK);
271 
272         for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
273                 if (ar[i].idx < 0)
274                         break;
275 
276                 ndx = rix_to_ndx(mi, ar[i].idx);
277                 if (ndx < 0)
278                         continue;
279 
280                 mi->r[ndx].stats.attempts += ar[i].count;
281 
282                 if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
283                         mi->r[ndx].stats.success += success;
284         }
285 
286         if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
287                 mi->sample_packets++;
288 
289         if (mi->sample_deferred > 0)
290                 mi->sample_deferred--;
291 
292         if (time_after(jiffies, mi->last_stats_update +
293                                 (mp->update_interval * HZ) / 1000))
294                 minstrel_update_stats(mp, mi);
295 }
296 
297 
298 static inline unsigned int
299 minstrel_get_retry_count(struct minstrel_rate *mr,
300                          struct ieee80211_tx_info *info)
301 {
302         u8 retry = mr->adjusted_retry_count;
303 
304         if (info->control.use_rts)
305                 retry = max_t(u8, 2, min(mr->stats.retry_count_rtscts, retry));
306         else if (info->control.use_cts_prot)
307                 retry = max_t(u8, 2, min(mr->retry_count_cts, retry));
308         return retry;
309 }
310 
311 
312 static int
313 minstrel_get_next_sample(struct minstrel_sta_info *mi)
314 {
315         unsigned int sample_ndx;
316         sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column);
317         mi->sample_row++;
318         if ((int) mi->sample_row >= mi->n_rates) {
319                 mi->sample_row = 0;
320                 mi->sample_column++;
321                 if (mi->sample_column >= SAMPLE_COLUMNS)
322                         mi->sample_column = 0;
323         }
324         return sample_ndx;
325 }
326 
327 static void
328 minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
329                   void *priv_sta, struct ieee80211_tx_rate_control *txrc)
330 {
331         struct sk_buff *skb = txrc->skb;
332         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
333         struct minstrel_sta_info *mi = priv_sta;
334         struct minstrel_priv *mp = priv;
335         struct ieee80211_tx_rate *rate = &info->control.rates[0];
336         struct minstrel_rate *msr, *mr;
337         unsigned int ndx;
338         bool mrr_capable;
339         bool prev_sample;
340         int delta;
341         int sampling_ratio;
342 
343         /* management/no-ack frames do not use rate control */
344         if (rate_control_send_low(sta, priv_sta, txrc))
345                 return;
346 
347         /* check multi-rate-retry capabilities & adjust lookaround_rate */
348         mrr_capable = mp->has_mrr &&
349                       !txrc->rts &&
350                       !txrc->bss_conf->use_cts_prot;
351         if (mrr_capable)
352                 sampling_ratio = mp->lookaround_rate_mrr;
353         else
354                 sampling_ratio = mp->lookaround_rate;
355 
356         /* increase sum packet counter */
357         mi->total_packets++;
358 
359 #ifdef CONFIG_MAC80211_DEBUGFS
360         if (mp->fixed_rate_idx != -1)
361                 return;
362 #endif
363 
364         /* Don't use EAPOL frames for sampling on non-mrr hw */
365         if (mp->hw->max_rates == 1 &&
366             (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
367                 return;
368 
369         delta = (mi->total_packets * sampling_ratio / 100) -
370                         (mi->sample_packets + mi->sample_deferred / 2);
371 
372         /* delta < 0: no sampling required */
373         prev_sample = mi->prev_sample;
374         mi->prev_sample = false;
375         if (delta < 0 || (!mrr_capable && prev_sample))
376                 return;
377 
378         if (mi->total_packets >= 10000) {
379                 mi->sample_deferred = 0;
380                 mi->sample_packets = 0;
381                 mi->total_packets = 0;
382         } else if (delta > mi->n_rates * 2) {
383                 /* With multi-rate retry, not every planned sample
384                  * attempt actually gets used, due to the way the retry
385                  * chain is set up - [max_tp,sample,prob,lowest] for
386                  * sample_rate < max_tp.
387                  *
388                  * If there's too much sampling backlog and the link
389                  * starts getting worse, minstrel would start bursting
390                  * out lots of sampling frames, which would result
391                  * in a large throughput loss. */
392                 mi->sample_packets += (delta - mi->n_rates * 2);
393         }
394 
395         /* get next random rate sample */
396         ndx = minstrel_get_next_sample(mi);
397         msr = &mi->r[ndx];
398         mr = &mi->r[mi->max_tp_rate[0]];
399 
400         /* Decide if direct ( 1st mrr stage) or indirect (2nd mrr stage)
401          * rate sampling method should be used.
402          * Respect such rates that are not sampled for 20 interations.
403          */
404         if (mrr_capable &&
405             msr->perfect_tx_time > mr->perfect_tx_time &&
406             msr->stats.sample_skipped < 20) {
407                 /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
408                  * packets that have the sampling rate deferred to the
409                  * second MRR stage. Increase the sample counter only
410                  * if the deferred sample rate was actually used.
411                  * Use the sample_deferred counter to make sure that
412                  * the sampling is not done in large bursts */
413                 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
414                 rate++;
415                 mi->sample_deferred++;
416         } else {
417                 if (!msr->sample_limit)
418                         return;
419 
420                 mi->sample_packets++;
421                 if (msr->sample_limit > 0)
422                         msr->sample_limit--;
423         }
424 
425         /* If we're not using MRR and the sampling rate already
426          * has a probability of >95%, we shouldn't be attempting
427          * to use it, as this only wastes precious airtime */
428         if (!mrr_capable &&
429            (mi->r[ndx].stats.prob_ewma > MINSTREL_FRAC(95, 100)))
430                 return;
431 
432         mi->prev_sample = true;
433 
434         rate->idx = mi->r[ndx].rix;
435         rate->count = minstrel_get_retry_count(&mi->r[ndx], info);
436 }
437 
438 
439 static void
440 calc_rate_durations(enum nl80211_band band,
441                     struct minstrel_rate *d,
442                     struct ieee80211_rate *rate,
443                     struct cfg80211_chan_def *chandef)
444 {
445         int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
446         int shift = ieee80211_chandef_get_shift(chandef);
447 
448         d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
449                         DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
450                         shift);
451         d->ack_time = ieee80211_frame_duration(band, 10,
452                         DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
453                         shift);
454 }
455 
456 static void
457 init_sample_table(struct minstrel_sta_info *mi)
458 {
459         unsigned int i, col, new_idx;
460         u8 rnd[8];
461 
462         mi->sample_column = 0;
463         mi->sample_row = 0;
464         memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates);
465 
466         for (col = 0; col < SAMPLE_COLUMNS; col++) {
467                 prandom_bytes(rnd, sizeof(rnd));
468                 for (i = 0; i < mi->n_rates; i++) {
469                         new_idx = (i + rnd[i & 7]) % mi->n_rates;
470                         while (SAMPLE_TBL(mi, new_idx, col) != 0xff)
471                                 new_idx = (new_idx + 1) % mi->n_rates;
472 
473                         SAMPLE_TBL(mi, new_idx, col) = i;
474                 }
475         }
476 }
477 
478 static void
479 minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
480                    struct cfg80211_chan_def *chandef,
481                    struct ieee80211_sta *sta, void *priv_sta)
482 {
483         struct minstrel_sta_info *mi = priv_sta;
484         struct minstrel_priv *mp = priv;
485         struct ieee80211_rate *ctl_rate;
486         unsigned int i, n = 0;
487         unsigned int t_slot = 9; /* FIXME: get real slot time */
488         u32 rate_flags;
489 
490         mi->sta = sta;
491         mi->lowest_rix = rate_lowest_index(sband, sta);
492         ctl_rate = &sband->bitrates[mi->lowest_rix];
493         mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10,
494                                 ctl_rate->bitrate,
495                                 !!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1,
496                                 ieee80211_chandef_get_shift(chandef));
497 
498         rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
499         memset(mi->max_tp_rate, 0, sizeof(mi->max_tp_rate));
500         mi->max_prob_rate = 0;
501 
502         for (i = 0; i < sband->n_bitrates; i++) {
503                 struct minstrel_rate *mr = &mi->r[n];
504                 struct minstrel_rate_stats *mrs = &mi->r[n].stats;
505                 unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
506                 unsigned int tx_time_single;
507                 unsigned int cw = mp->cw_min;
508                 int shift;
509 
510                 if (!rate_supported(sta, sband->band, i))
511                         continue;
512                 if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
513                         continue;
514 
515                 n++;
516                 memset(mr, 0, sizeof(*mr));
517                 memset(mrs, 0, sizeof(*mrs));
518 
519                 mr->rix = i;
520                 shift = ieee80211_chandef_get_shift(chandef);
521                 mr->bitrate = DIV_ROUND_UP(sband->bitrates[i].bitrate,
522                                            (1 << shift) * 5);
523                 calc_rate_durations(sband->band, mr, &sband->bitrates[i],
524                                     chandef);
525 
526                 /* calculate maximum number of retransmissions before
527                  * fallback (based on maximum segment size) */
528                 mr->sample_limit = -1;
529                 mrs->retry_count = 1;
530                 mr->retry_count_cts = 1;
531                 mrs->retry_count_rtscts = 1;
532                 tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
533                 do {
534                         /* add one retransmission */
535                         tx_time_single = mr->ack_time + mr->perfect_tx_time;
536 
537                         /* contention window */
538                         tx_time_single += (t_slot * cw) >> 1;
539                         cw = min((cw << 1) | 1, mp->cw_max);
540 
541                         tx_time += tx_time_single;
542                         tx_time_cts += tx_time_single + mi->sp_ack_dur;
543                         tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
544                         if ((tx_time_cts < mp->segment_size) &&
545                                 (mr->retry_count_cts < mp->max_retry))
546                                 mr->retry_count_cts++;
547                         if ((tx_time_rtscts < mp->segment_size) &&
548                                 (mrs->retry_count_rtscts < mp->max_retry))
549                                 mrs->retry_count_rtscts++;
550                 } while ((tx_time < mp->segment_size) &&
551                                 (++mr->stats.retry_count < mp->max_retry));
552                 mr->adjusted_retry_count = mrs->retry_count;
553                 if (!(sband->bitrates[i].flags & IEEE80211_RATE_ERP_G))
554                         mr->retry_count_cts = mrs->retry_count;
555         }
556 
557         for (i = n; i < sband->n_bitrates; i++) {
558                 struct minstrel_rate *mr = &mi->r[i];
559                 mr->rix = -1;
560         }
561 
562         mi->n_rates = n;
563         mi->last_stats_update = jiffies;
564 
565         init_sample_table(mi);
566         minstrel_update_rates(mp, mi);
567 }
568 
569 static u32 minstrel_get_expected_throughput(void *priv_sta)
570 {
571         struct minstrel_sta_info *mi = priv_sta;
572         struct minstrel_rate_stats *tmp_mrs;
573         int idx = mi->max_tp_rate[0];
574         int tmp_cur_tp;
575 
576         /* convert pkt per sec in kbps (1200 is the average pkt size used for
577          * computing cur_tp
578          */
579         tmp_mrs = &mi->r[idx].stats;
580         tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_ewma) * 10;
581         tmp_cur_tp = tmp_cur_tp * 1200 * 8 / 1024;
582 
583         return tmp_cur_tp;
584 }
585 
586 const struct rate_control_ops mac80211_minstrel = {
587         .tx_status_ext = minstrel_tx_status,
588         .get_rate = minstrel_get_rate,
589         .rate_init = minstrel_rate_init,
590         .get_expected_throughput = minstrel_get_expected_throughput,
591 };
592 

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