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 = mac80211_open_file_generic,
 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         kref_init(&ref->kref);
 163         ref->local = local;
 164         ref->ops = ieee80211_rate_control_ops_get(name);
 165         if (!ref->ops)
 166                 goto fail_ops;
 167
 168 #ifdef CONFIG_MAC80211_DEBUGFS
 169         debugfsdir = debugfs_create_dir("rc", local->hw.wiphy->debugfsdir);
 170         local->debugfs.rcdir = debugfsdir;
 171         debugfs_create_file("name", 0400, debugfsdir, ref, &rcname_ops);
 172 #endif
 173
 174         ref->priv = ref->ops->alloc(&local->hw, debugfsdir);
 175         if (!ref->priv)
 176                 goto fail_priv;
 177         return ref;
 178
 179 fail_priv:
 180         ieee80211_rate_control_ops_put(ref->ops);
 181 fail_ops:
 182         kfree(ref);
 183 fail_ref:
 184         return NULL;
 185 }
 186
 187 static void rate_control_release(struct kref *kref)
 188 {
 189         struct rate_control_ref *ctrl_ref;
 190
 191         ctrl_ref = container_of(kref, struct rate_control_ref, kref);
 192         ctrl_ref->ops->free(ctrl_ref->priv);
 193
 194 #ifdef CONFIG_MAC80211_DEBUGFS
 195         debugfs_remove_recursive(ctrl_ref->local->debugfs.rcdir);
 196         ctrl_ref->local->debugfs.rcdir = NULL;
 197 #endif
 198
 199         ieee80211_rate_control_ops_put(ctrl_ref->ops);
 200         kfree(ctrl_ref);
 201 }
 202
 203 static bool rc_no_data_or_no_ack_use_min(struct ieee80211_tx_rate_control *txrc)
 204 {
 205         struct sk_buff *skb = txrc->skb;
 206         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 207         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 208         __le16 fc;
 209
 210         fc = hdr->frame_control;
 211
 212         return (info->flags & (IEEE80211_TX_CTL_NO_ACK |
 213                                IEEE80211_TX_CTL_USE_MINRATE)) ||
 214                 !ieee80211_is_data(fc);
 215 }
 216
 217 static void rc_send_low_broadcast(s8 *idx, u32 basic_rates,
 218                                   struct ieee80211_supported_band *sband)
 219 {
 220         u8 i;
 221
 222         if (basic_rates == 0)
 223                 return; /* assume basic rates unknown and accept rate */
 224         if (*idx < 0)
 225                 return;
 226         if (basic_rates & (1 << *idx))
 227                 return; /* selected rate is a basic rate */
 228
 229         for (i = *idx + 1; i <= sband->n_bitrates; i++) {
 230                 if (basic_rates & (1 << i)) {
 231                         *idx = i;
 232                         return;
 233                 }
 234         }
 235
 236         /* could not find a basic rate; use original selection */
 237 }
 238
 239 static inline s8
 240 rate_lowest_non_cck_index(struct ieee80211_supported_band *sband,
 241                           struct ieee80211_sta *sta)
 242 {
 243         int i;
 244
 245         for (i = 0; i < sband->n_bitrates; i++) {
 246                 struct ieee80211_rate *srate = &sband->bitrates[i];
 247                 if ((srate->bitrate == 10) || (srate->bitrate == 20) ||
 248                     (srate->bitrate == 55) || (srate->bitrate == 110))
 249                         continue;
 250
 251                 if (rate_supported(sta, sband->band, i))
 252                         return i;
 253         }
 254
 255         /* No matching rate found */
 256         return 0;
 257 }
 258
 259
 260 bool rate_control_send_low(struct ieee80211_sta *sta,
 261                            void *priv_sta,
 262                            struct ieee80211_tx_rate_control *txrc)
 263 {
 264         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 265         struct ieee80211_supported_band *sband = txrc->sband;
 266         int mcast_rate;
 267
 268         if (!sta || !priv_sta || rc_no_data_or_no_ack_use_min(txrc)) {
 269                 if ((sband->band != IEEE80211_BAND_2GHZ) ||
 270                     !(info->flags & IEEE80211_TX_CTL_NO_CCK_RATE))
 271                         info->control.rates[0].idx =
 272                                 rate_lowest_index(txrc->sband, sta);
 273                 else
 274                         info->control.rates[0].idx =
 275                                 rate_lowest_non_cck_index(txrc->sband, sta);
 276                 info->control.rates[0].count =
 277                         (info->flags & IEEE80211_TX_CTL_NO_ACK) ?
 278                         1 : txrc->hw->max_rate_tries;
 279                 if (!sta && txrc->bss) {
 280                         mcast_rate = txrc->bss_conf->mcast_rate[sband->band];
 281                         if (mcast_rate > 0) {
 282                                 info->control.rates[0].idx = mcast_rate - 1;
 283                                 return true;
 284                         }
 285
 286                         rc_send_low_broadcast(&info->control.rates[0].idx,
 287                                               txrc->bss_conf->basic_rates,
 288                                               sband);
 289                 }
 290                 return true;
 291         }
 292         return false;
 293 }
 294 EXPORT_SYMBOL(rate_control_send_low);
 295
 296 static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
 297                                 int n_bitrates, u32 mask)
 298 {
 299         int j;
 300
 301         /* See whether the selected rate or anything below it is allowed. */
 302         for (j = rate->idx; j >= 0; j--) {
 303                 if (mask & (1 << j)) {
 304                         /* Okay, found a suitable rate. Use it. */
 305                         rate->idx = j;
 306                         return;
 307                 }
 308         }
 309
 310         /* Try to find a higher rate that would be allowed */
 311         for (j = rate->idx + 1; j < n_bitrates; j++) {
 312                 if (mask & (1 << j)) {
 313                         /* Okay, found a suitable rate. Use it. */
 314                         rate->idx = j;
 315                         return;
 316                 }
 317         }
 318
 319         /*
 320          * Uh.. No suitable rate exists. This should not really happen with
 321          * sane TX rate mask configurations. However, should someone manage to
 322          * configure supported rates and TX rate mask in incompatible way,
 323          * allow the frame to be transmitted with whatever the rate control
 324          * selected.
 325          */
 326 }
 327
 328 void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
 329                            struct sta_info *sta,
 330                            struct ieee80211_tx_rate_control *txrc)
 331 {
 332         struct rate_control_ref *ref = sdata->local->rate_ctrl;
 333         void *priv_sta = NULL;
 334         struct ieee80211_sta *ista = NULL;
 335         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 336         int i;
 337         u32 mask;
 338
 339         if (sta) {
 340                 ista = &sta->sta;
 341                 priv_sta = sta->rate_ctrl_priv;
 342         }
 343
 344         for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 345                 info->control.rates[i].idx = -1;
 346                 info->control.rates[i].flags = 0;
 347                 info->control.rates[i].count = 1;
 348         }
 349
 350         if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
 351                 return;
 352
 353         ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
 354
 355         /*
 356          * Try to enforce the rateidx mask the user wanted. skip this if the
 357          * default mask (allow all rates) is used to save some processing for
 358          * the common case.
 359          */
 360         mask = sdata->rc_rateidx_mask[info->band];
 361         if (mask != (1 << txrc->sband->n_bitrates) - 1) {
 362                 if (sta) {
 363                         /* Filter out rates that the STA does not support */
 364                         mask &= sta->sta.supp_rates[info->band];
 365                 }
 366                 /*
 367                  * Make sure the rate index selected for each TX rate is
 368                  * included in the configured mask and change the rate indexes
 369                  * if needed.
 370                  */
 371                 for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 372                         /* Skip invalid rates */
 373                         if (info->control.rates[i].idx < 0)
 374                                 break;
 375                         /* Rate masking supports only legacy rates for now */
 376                         if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS)
 377                                 continue;
 378                         rate_idx_match_mask(&info->control.rates[i],
 379                                             txrc->sband->n_bitrates, mask);
 380                 }
 381         }
 382
 383         BUG_ON(info->control.rates[0].idx < 0);
 384 }
 385
 386 struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
 387 {
 388         kref_get(&ref->kref);
 389         return ref;
 390 }
 391
 392 void rate_control_put(struct rate_control_ref *ref)
 393 {
 394         kref_put(&ref->kref, rate_control_release);
 395 }
 396
 397 int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
 398                                  const char *name)
 399 {
 400         struct rate_control_ref *ref, *old;
 401
 402         ASSERT_RTNL();
 403
 404         if (local->open_count)
 405                 return -EBUSY;
 406
 407         if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
 408                 if (WARN_ON(!local->ops->set_rts_threshold))
 409                         return -EINVAL;
 410                 return 0;
 411         }
 412
 413         ref = rate_control_alloc(name, local);
 414         if (!ref) {
 415                 wiphy_warn(local->hw.wiphy,
 416                            "Failed to select rate control algorithm\n");
 417                 return -ENOENT;
 418         }
 419
 420         old = local->rate_ctrl;
 421         local->rate_ctrl = ref;
 422         if (old) {
 423                 rate_control_put(old);
 424                 sta_info_flush(local, NULL);
 425         }
 426
 427         wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
 428                     ref->ops->name);
 429
 430         return 0;
 431 }
 432
 433 void rate_control_deinitialize(struct ieee80211_local *local)
 434 {
 435         struct rate_control_ref *ref;
 436
 437         ref = local->rate_ctrl;
 438
 439         if (!ref)
 440                 return;
 441
 442         local->rate_ctrl = NULL;
 443         rate_control_put(ref);
 444 }
 445