net/mac80211/rate.c

   1 /*
   2  * Copyright 2002-2005, Instant802 Networks, Inc.
   3  * Copyright 2005-2006, Devicescape Software, Inc.
   4  * Copyright (c) 2006 Jiri Benc <jbenc@suse.cz>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/rtnetlink.h>
  13 #include <linux/slab.h>
  14 #include <linux/module.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         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 int ieee80211_rate_control_register(struct rate_control_ops *ops)
  33 {
  34         struct rate_control_alg *alg;
  35
  36         if (!ops->name)
  37                 return -EINVAL;
  38
  39         mutex_lock(&rate_ctrl_mutex);
  40         list_for_each_entry(alg, &rate_ctrl_algs, list) {
  41                 if (!strcmp(alg->ops->name, ops->name)) {
  42                         /* don't register an algorithm twice */
  43                         WARN_ON(1);
  44                         mutex_unlock(&rate_ctrl_mutex);
  45                         return -EALREADY;
  46                 }
  47         }
  48
  49         alg = kzalloc(sizeof(*alg), GFP_KERNEL);
  50         if (alg == NULL) {
  51                 mutex_unlock(&rate_ctrl_mutex);
  52                 return -ENOMEM;
  53         }
  54         alg->ops = ops;
  55
  56         list_add_tail(&alg->list, &rate_ctrl_algs);
  57         mutex_unlock(&rate_ctrl_mutex);
  58
  59         return 0;
  60 }
  61 EXPORT_SYMBOL(ieee80211_rate_control_register);
  62
  63 void ieee80211_rate_control_unregister(struct rate_control_ops *ops)
  64 {
  65         struct rate_control_alg *alg;
  66
  67         mutex_lock(&rate_ctrl_mutex);
  68         list_for_each_entry(alg, &rate_ctrl_algs, list) {
  69                 if (alg->ops == ops) {
  70                         list_del(&alg->list);
  71                         kfree(alg);
  72                         break;
  73                 }
  74         }
  75         mutex_unlock(&rate_ctrl_mutex);
  76 }
  77 EXPORT_SYMBOL(ieee80211_rate_control_unregister);
  78
  79 static struct rate_control_ops *
  80 ieee80211_try_rate_control_ops_get(const char *name)
  81 {
  82         struct rate_control_alg *alg;
  83         struct rate_control_ops *ops = NULL;
  84
  85         if (!name)
  86                 return NULL;
  87
  88         mutex_lock(&rate_ctrl_mutex);
  89         list_for_each_entry(alg, &rate_ctrl_algs, list) {
  90                 if (!strcmp(alg->ops->name, name))
  91                         if (try_module_get(alg->ops->module)) {
  92                                 ops = alg->ops;
  93                                 break;
  94                         }
  95         }
  96         mutex_unlock(&rate_ctrl_mutex);
  97         return ops;
  98 }
  99
 100 /* Get the rate control algorithm. */
 101 static struct rate_control_ops *
 102 ieee80211_rate_control_ops_get(const char *name)
 103 {
 104         struct rate_control_ops *ops;
 105         const char *alg_name;
 106
 107         kparam_block_sysfs_write(ieee80211_default_rc_algo);
 108         if (!name)
 109                 alg_name = ieee80211_default_rc_algo;
 110         else
 111                 alg_name = name;
 112
 113         ops = ieee80211_try_rate_control_ops_get(alg_name);
 114         if (!ops) {
 115                 request_module("rc80211_%s", alg_name);
 116                 ops = ieee80211_try_rate_control_ops_get(alg_name);
 117         }
 118         if (!ops && name)
 119                 /* try default if specific alg requested but not found */
 120                 ops = ieee80211_try_rate_control_ops_get(ieee80211_default_rc_algo);
 121
 122         /* try built-in one if specific alg requested but not found */
 123         if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
 124                 ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
 125         kparam_unblock_sysfs_write(ieee80211_default_rc_algo);
 126
 127         return ops;
 128 }
 129
 130 static void ieee80211_rate_control_ops_put(struct rate_control_ops *ops)
 131 {
 132         module_put(ops->module);
 133 }
 134
 135 #ifdef CONFIG_MAC80211_DEBUGFS
 136 static ssize_t rcname_read(struct file *file, char __user *userbuf,
 137                            size_t count, loff_t *ppos)
 138 {
 139         struct rate_control_ref *ref = file->private_data;
 140         int len = strlen(ref->ops->name);
 141
 142         return simple_read_from_buffer(userbuf, count, ppos,
 143                                        ref->ops->name, len);
 144 }
 145
 146 static const struct file_operations rcname_ops = {
 147         .read = rcname_read,
 148         .open = simple_open,
 149         .llseek = default_llseek,
 150 };
 151 #endif
 152
 153 static struct rate_control_ref *rate_control_alloc(const char *name,
 154                                             struct ieee80211_local *local)
 155 {
 156         struct dentry *debugfsdir = NULL;
 157         struct rate_control_ref *ref;
 158
 159         ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
 160         if (!ref)
 161                 goto fail_ref;
 162         ref->local = local;
 163         ref->ops = ieee80211_rate_control_ops_get(name);
 164         if (!ref->ops)
 165                 goto fail_ops;
 166
 167 #ifdef CONFIG_MAC80211_DEBUGFS
 168         debugfsdir = debugfs_create_dir("rc", local->hw.wiphy->debugfsdir);
 169         local->debugfs.rcdir = debugfsdir;
 170         debugfs_create_file("name", 0400, debugfsdir, ref, &rcname_ops);
 171 #endif
 172
 173         ref->priv = ref->ops->alloc(&local->hw, debugfsdir);
 174         if (!ref->priv)
 175                 goto fail_priv;
 176         return ref;
 177
 178 fail_priv:
 179         ieee80211_rate_control_ops_put(ref->ops);
 180 fail_ops:
 181         kfree(ref);
 182 fail_ref:
 183         return NULL;
 184 }
 185
 186 static void rate_control_free(struct rate_control_ref *ctrl_ref)
 187 {
 188         ctrl_ref->ops->free(ctrl_ref->priv);
 189
 190 #ifdef CONFIG_MAC80211_DEBUGFS
 191         debugfs_remove_recursive(ctrl_ref->local->debugfs.rcdir);
 192         ctrl_ref->local->debugfs.rcdir = NULL;
 193 #endif
 194
 195         ieee80211_rate_control_ops_put(ctrl_ref->ops);
 196         kfree(ctrl_ref);
 197 }
 198
 199 static bool rc_no_data_or_no_ack_use_min(struct ieee80211_tx_rate_control *txrc)
 200 {
 201         struct sk_buff *skb = txrc->skb;
 202         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 203         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 204         __le16 fc;
 205
 206         fc = hdr->frame_control;
 207
 208         return (info->flags & (IEEE80211_TX_CTL_NO_ACK |
 209                                IEEE80211_TX_CTL_USE_MINRATE)) ||
 210                 !ieee80211_is_data(fc);
 211 }
 212
 213 static void rc_send_low_broadcast(s8 *idx, u32 basic_rates,
 214                                   struct ieee80211_supported_band *sband)
 215 {
 216         u8 i;
 217
 218         if (basic_rates == 0)
 219                 return; /* assume basic rates unknown and accept rate */
 220         if (*idx < 0)
 221                 return;
 222         if (basic_rates & (1 << *idx))
 223                 return; /* selected rate is a basic rate */
 224
 225         for (i = *idx + 1; i <= sband->n_bitrates; i++) {
 226                 if (basic_rates & (1 << i)) {
 227                         *idx = i;
 228                         return;
 229                 }
 230         }
 231
 232         /* could not find a basic rate; use original selection */
 233 }
 234
 235 static inline s8
 236 rate_lowest_non_cck_index(struct ieee80211_supported_band *sband,
 237                           struct ieee80211_sta *sta)
 238 {
 239         int i;
 240
 241         for (i = 0; i < sband->n_bitrates; i++) {
 242                 struct ieee80211_rate *srate = &sband->bitrates[i];
 243                 if ((srate->bitrate == 10) || (srate->bitrate == 20) ||
 244                     (srate->bitrate == 55) || (srate->bitrate == 110))
 245                         continue;
 246
 247                 if (rate_supported(sta, sband->band, i))
 248                         return i;
 249         }
 250
 251         /* No matching rate found */
 252         return 0;
 253 }
 254
 255
 256 bool rate_control_send_low(struct ieee80211_sta *sta,
 257                            void *priv_sta,
 258                            struct ieee80211_tx_rate_control *txrc)
 259 {
 260         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 261         struct ieee80211_supported_band *sband = txrc->sband;
 262         int mcast_rate;
 263
 264         if (!sta || !priv_sta || rc_no_data_or_no_ack_use_min(txrc)) {
 265                 if ((sband->band != IEEE80211_BAND_2GHZ) ||
 266                     !(info->flags & IEEE80211_TX_CTL_NO_CCK_RATE))
 267                         info->control.rates[0].idx =
 268                                 rate_lowest_index(txrc->sband, sta);
 269                 else
 270                         info->control.rates[0].idx =
 271                                 rate_lowest_non_cck_index(txrc->sband, sta);
 272                 info->control.rates[0].count =
 273                         (info->flags & IEEE80211_TX_CTL_NO_ACK) ?
 274                         1 : txrc->hw->max_rate_tries;
 275                 if (!sta && txrc->bss) {
 276                         mcast_rate = txrc->bss_conf->mcast_rate[sband->band];
 277                         if (mcast_rate > 0) {
 278                                 info->control.rates[0].idx = mcast_rate - 1;
 279                                 return true;
 280                         }
 281
 282                         rc_send_low_broadcast(&info->control.rates[0].idx,
 283                                               txrc->bss_conf->basic_rates,
 284                                               sband);
 285                 }
 286                 return true;
 287         }
 288         return false;
 289 }
 290 EXPORT_SYMBOL(rate_control_send_low);
 291
 292 static bool rate_idx_match_legacy_mask(struct ieee80211_tx_rate *rate,
 293                                        int n_bitrates, u32 mask)
 294 {
 295         int j;
 296
 297         /* See whether the selected rate or anything below it is allowed. */
 298         for (j = rate->idx; j >= 0; j--) {
 299                 if (mask & (1 << j)) {
 300                         /* Okay, found a suitable rate. Use it. */
 301                         rate->idx = j;
 302                         return true;
 303                 }
 304         }
 305
 306         /* Try to find a higher rate that would be allowed */
 307         for (j = rate->idx + 1; j < n_bitrates; j++) {
 308                 if (mask & (1 << j)) {
 309                         /* Okay, found a suitable rate. Use it. */
 310                         rate->idx = j;
 311                         return true;
 312                 }
 313         }
 314         return false;
 315 }
 316
 317 static bool rate_idx_match_mcs_mask(struct ieee80211_tx_rate *rate,
 318                                     u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN])
 319 {
 320         int i, j;
 321         int ridx, rbit;
 322
 323         ridx = rate->idx / 8;
 324         rbit = rate->idx % 8;
 325
 326         /* sanity check */
 327         if (ridx < 0 || ridx >= IEEE80211_HT_MCS_MASK_LEN)
 328                 return false;
 329
 330         /* See whether the selected rate or anything below it is allowed. */
 331         for (i = ridx; i >= 0; i--) {
 332                 for (j = rbit; j >= 0; j--)
 333                         if (mcs_mask[i] & BIT(j)) {
 334                                 rate->idx = i * 8 + j;
 335                                 return true;
 336                         }
 337                 rbit = 7;
 338         }
 339
 340         /* Try to find a higher rate that would be allowed */
 341         ridx = (rate->idx + 1) / 8;
 342         rbit = (rate->idx + 1) % 8;
 343
 344         for (i = ridx; i < IEEE80211_HT_MCS_MASK_LEN; i++) {
 345                 for (j = rbit; j < 8; j++)
 346                         if (mcs_mask[i] & BIT(j)) {
 347                                 rate->idx = i * 8 + j;
 348                                 return true;
 349                         }
 350                 rbit = 0;
 351         }
 352         return false;
 353 }
 354
 355
 356
 357 static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
 358                                 struct ieee80211_tx_rate_control *txrc,
 359                                 u32 mask,
 360                                 u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN])
 361 {
 362         struct ieee80211_tx_rate alt_rate;
 363
 364         /* handle HT rates */
 365         if (rate->flags & IEEE80211_TX_RC_MCS) {
 366                 if (rate_idx_match_mcs_mask(rate, mcs_mask))
 367                         return;
 368
 369                 /* also try the legacy rates. */
 370                 alt_rate.idx = 0;
 371                 /* keep protection flags */
 372                 alt_rate.flags = rate->flags &
 373                                  (IEEE80211_TX_RC_USE_RTS_CTS |
 374                                   IEEE80211_TX_RC_USE_CTS_PROTECT |
 375                                   IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
 376                 alt_rate.count = rate->count;
 377                 if (rate_idx_match_legacy_mask(&alt_rate,
 378                                                txrc->sband->n_bitrates,
 379                                                mask)) {
 380                         *rate = alt_rate;
 381                         return;
 382                 }
 383         } else {
 384                 struct sk_buff *skb = txrc->skb;
 385                 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 386                 __le16 fc;
 387
 388                 /* handle legacy rates */
 389                 if (rate_idx_match_legacy_mask(rate, txrc->sband->n_bitrates,
 390                                                mask))
 391                         return;
 392
 393                 /* if HT BSS, and we handle a data frame, also try HT rates */
 394                 if (txrc->bss_conf->chandef.width == NL80211_CHAN_WIDTH_20_NOHT)
 395                         return;
 396
 397                 fc = hdr->frame_control;
 398                 if (!ieee80211_is_data(fc))
 399                         return;
 400
 401                 alt_rate.idx = 0;
 402                 /* keep protection flags */
 403                 alt_rate.flags = rate->flags &
 404                                  (IEEE80211_TX_RC_USE_RTS_CTS |
 405                                   IEEE80211_TX_RC_USE_CTS_PROTECT |
 406                                   IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
 407                 alt_rate.count = rate->count;
 408
 409                 alt_rate.flags |= IEEE80211_TX_RC_MCS;
 410
 411                 if (txrc->bss_conf->chandef.width == NL80211_CHAN_WIDTH_40)
 412                         alt_rate.flags |= IEEE80211_TX_RC_40_MHZ_WIDTH;
 413
 414                 if (rate_idx_match_mcs_mask(&alt_rate, mcs_mask)) {
 415                         *rate = alt_rate;
 416                         return;
 417                 }
 418         }
 419
 420         /*
 421          * Uh.. No suitable rate exists. This should not really happen with
 422          * sane TX rate mask configurations. However, should someone manage to
 423          * configure supported rates and TX rate mask in incompatible way,
 424          * allow the frame to be transmitted with whatever the rate control
 425          * selected.
 426          */
 427 }
 428
 429 void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
 430                            struct sta_info *sta,
 431                            struct ieee80211_tx_rate_control *txrc)
 432 {
 433         struct rate_control_ref *ref = sdata->local->rate_ctrl;
 434         void *priv_sta = NULL;
 435         struct ieee80211_sta *ista = NULL;
 436         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 437         int i;
 438         u32 mask;
 439         u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN];
 440
 441         if (sta && test_sta_flag(sta, WLAN_STA_RATE_CONTROL)) {
 442                 ista = &sta->sta;
 443                 priv_sta = sta->rate_ctrl_priv;
 444         }
 445
 446         for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 447                 info->control.rates[i].idx = -1;
 448                 info->control.rates[i].flags = 0;
 449                 info->control.rates[i].count = 0;
 450         }
 451
 452         if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
 453                 return;
 454
 455         ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
 456
 457         /*
 458          * Try to enforce the rateidx mask the user wanted. skip this if the
 459          * default mask (allow all rates) is used to save some processing for
 460          * the common case.
 461          */
 462         mask = sdata->rc_rateidx_mask[info->band];
 463         memcpy(mcs_mask, sdata->rc_rateidx_mcs_mask[info->band],
 464                sizeof(mcs_mask));
 465         if (mask != (1 << txrc->sband->n_bitrates) - 1) {
 466                 if (sta) {
 467                         /* Filter out rates that the STA does not support */
 468                         mask &= sta->sta.supp_rates[info->band];
 469                         for (i = 0; i < sizeof(mcs_mask); i++)
 470                                 mcs_mask[i] &= sta->sta.ht_cap.mcs.rx_mask[i];
 471                 }
 472                 /*
 473                  * Make sure the rate index selected for each TX rate is
 474                  * included in the configured mask and change the rate indexes
 475                  * if needed.
 476                  */
 477                 for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 478                         /* Skip invalid rates */
 479                         if (info->control.rates[i].idx < 0)
 480                                 break;
 481                         rate_idx_match_mask(&info->control.rates[i], txrc,
 482                                             mask, mcs_mask);
 483                 }
 484         }
 485
 486         BUG_ON(info->control.rates[0].idx < 0);
 487 }
 488
 489 int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
 490                                  const char *name)
 491 {
 492         struct rate_control_ref *ref;
 493
 494         ASSERT_RTNL();
 495
 496         if (local->open_count)
 497                 return -EBUSY;
 498
 499         if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
 500                 if (WARN_ON(!local->ops->set_rts_threshold))
 501                         return -EINVAL;
 502                 return 0;
 503         }
 504
 505         ref = rate_control_alloc(name, local);
 506         if (!ref) {
 507                 wiphy_warn(local->hw.wiphy,
 508                            "Failed to select rate control algorithm\n");
 509                 return -ENOENT;
 510         }
 511
 512         WARN_ON(local->rate_ctrl);
 513         local->rate_ctrl = ref;
 514
 515         wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
 516                     ref->ops->name);
 517
 518         return 0;
 519 }
 520
 521 void rate_control_deinitialize(struct ieee80211_local *local)
 522 {
 523         struct rate_control_ref *ref;
 524
 525         ref = local->rate_ctrl;
 526
 527         if (!ref)
 528                 return;
 529
 530         local->rate_ctrl = NULL;
 531         rate_control_free(ref);
 532 }
 533