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 "rate.h"
  15 #include "ieee80211_i.h"
  16 #include "debugfs.h"
  17
  18 struct rate_control_alg {
  19         struct list_head list;
  20         struct rate_control_ops *ops;
  21 };
  22
  23 static LIST_HEAD(rate_ctrl_algs);
  24 static DEFINE_MUTEX(rate_ctrl_mutex);
  25
  26 static char *ieee80211_default_rc_algo = CONFIG_MAC80211_RC_DEFAULT;
  27 module_param(ieee80211_default_rc_algo, charp, 0644);
  28 MODULE_PARM_DESC(ieee80211_default_rc_algo,
  29                  "Default rate control algorithm for mac80211 to use");
  30
  31 int ieee80211_rate_control_register(struct rate_control_ops *ops)
  32 {
  33         struct rate_control_alg *alg;
  34
  35         if (!ops->name)
  36                 return -EINVAL;
  37
  38         mutex_lock(&rate_ctrl_mutex);
  39         list_for_each_entry(alg, &rate_ctrl_algs, list) {
  40                 if (!strcmp(alg->ops->name, ops->name)) {
  41                         /* don't register an algorithm twice */
  42                         WARN_ON(1);
  43                         mutex_unlock(&rate_ctrl_mutex);
  44                         return -EALREADY;
  45                 }
  46         }
  47
  48         alg = kzalloc(sizeof(*alg), GFP_KERNEL);
  49         if (alg == NULL) {
  50                 mutex_unlock(&rate_ctrl_mutex);
  51                 return -ENOMEM;
  52         }
  53         alg->ops = ops;
  54
  55         list_add_tail(&alg->list, &rate_ctrl_algs);
  56         mutex_unlock(&rate_ctrl_mutex);
  57
  58         return 0;
  59 }
  60 EXPORT_SYMBOL(ieee80211_rate_control_register);
  61
  62 void ieee80211_rate_control_unregister(struct rate_control_ops *ops)
  63 {
  64         struct rate_control_alg *alg;
  65
  66         mutex_lock(&rate_ctrl_mutex);
  67         list_for_each_entry(alg, &rate_ctrl_algs, list) {
  68                 if (alg->ops == ops) {
  69                         list_del(&alg->list);
  70                         kfree(alg);
  71                         break;
  72                 }
  73         }
  74         mutex_unlock(&rate_ctrl_mutex);
  75 }
  76 EXPORT_SYMBOL(ieee80211_rate_control_unregister);
  77
  78 static struct rate_control_ops *
  79 ieee80211_try_rate_control_ops_get(const char *name)
  80 {
  81         struct rate_control_alg *alg;
  82         struct rate_control_ops *ops = NULL;
  83
  84         if (!name)
  85                 return NULL;
  86
  87         mutex_lock(&rate_ctrl_mutex);
  88         list_for_each_entry(alg, &rate_ctrl_algs, list) {
  89                 if (!strcmp(alg->ops->name, name))
  90                         if (try_module_get(alg->ops->module)) {
  91                                 ops = alg->ops;
  92                                 break;
  93                         }
  94         }
  95         mutex_unlock(&rate_ctrl_mutex);
  96         return ops;
  97 }
  98
  99 /* Get the rate control algorithm. */
 100 static struct rate_control_ops *
 101 ieee80211_rate_control_ops_get(const char *name)
 102 {
 103         struct rate_control_ops *ops;
 104         const char *alg_name;
 105
 106         kparam_block_sysfs_write(ieee80211_default_rc_algo);
 107         if (!name)
 108                 alg_name = ieee80211_default_rc_algo;
 109         else
 110                 alg_name = name;
 111
 112         ops = ieee80211_try_rate_control_ops_get(alg_name);
 113         if (!ops) {
 114                 request_module("rc80211_%s", alg_name);
 115                 ops = ieee80211_try_rate_control_ops_get(alg_name);
 116         }
 117         if (!ops && name)
 118                 /* try default if specific alg requested but not found */
 119                 ops = ieee80211_try_rate_control_ops_get(ieee80211_default_rc_algo);
 120
 121         /* try built-in one if specific alg requested but not found */
 122         if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
 123                 ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
 124         kparam_unblock_sysfs_write(ieee80211_default_rc_algo);
 125
 126         return ops;
 127 }
 128
 129 static void ieee80211_rate_control_ops_put(struct rate_control_ops *ops)
 130 {
 131         module_put(ops->module);
 132 }
 133
 134 #ifdef CONFIG_MAC80211_DEBUGFS
 135 static ssize_t rcname_read(struct file *file, char __user *userbuf,
 136                            size_t count, loff_t *ppos)
 137 {
 138         struct rate_control_ref *ref = file->private_data;
 139         int len = strlen(ref->ops->name);
 140
 141         return simple_read_from_buffer(userbuf, count, ppos,
 142                                        ref->ops->name, len);
 143 }
 144
 145 static const struct file_operations rcname_ops = {
 146         .read = rcname_read,
 147         .open = mac80211_open_file_generic,
 148         .llseek = default_llseek,
 149 };
 150 #endif
 151
 152 static struct rate_control_ref *rate_control_alloc(const char *name,
 153                                             struct ieee80211_local *local)
 154 {
 155         struct dentry *debugfsdir = NULL;
 156         struct rate_control_ref *ref;
 157
 158         ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
 159         if (!ref)
 160                 goto fail_ref;
 161         kref_init(&ref->kref);
 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_release(struct kref *kref)
 187 {
 188         struct rate_control_ref *ctrl_ref;
 189
 190         ctrl_ref = container_of(kref, struct rate_control_ref, kref);
 191         ctrl_ref->ops->free(ctrl_ref->priv);
 192
 193 #ifdef CONFIG_MAC80211_DEBUGFS
 194         debugfs_remove_recursive(ctrl_ref->local->debugfs.rcdir);
 195         ctrl_ref->local->debugfs.rcdir = NULL;
 196 #endif
 197
 198         ieee80211_rate_control_ops_put(ctrl_ref->ops);
 199         kfree(ctrl_ref);
 200 }
 201
 202 static bool rc_no_data_or_no_ack(struct ieee80211_tx_rate_control *txrc)
 203 {
 204         struct sk_buff *skb = txrc->skb;
 205         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 206         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 207         __le16 fc;
 208
 209         fc = hdr->frame_control;
 210
 211         return (info->flags & IEEE80211_TX_CTL_NO_ACK) || !ieee80211_is_data(fc);
 212 }
 213
 214 static void rc_send_low_broadcast(s8 *idx, u32 basic_rates, u8 max_rate_idx)
 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 <= max_rate_idx; 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 bool rate_control_send_low(struct ieee80211_sta *sta,
 236                            void *priv_sta,
 237                            struct ieee80211_tx_rate_control *txrc)
 238 {
 239         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 240
 241         if (!sta || !priv_sta || rc_no_data_or_no_ack(txrc)) {
 242                 info->control.rates[0].idx = rate_lowest_index(txrc->sband, sta);
 243                 info->control.rates[0].count =
 244                         (info->flags & IEEE80211_TX_CTL_NO_ACK) ?
 245                         1 : txrc->hw->max_rate_tries;
 246                 if (!sta && txrc->ap)
 247                         rc_send_low_broadcast(&info->control.rates[0].idx,
 248                                               txrc->bss_conf->basic_rates,
 249                                               txrc->sband->n_bitrates);
 250                 return true;
 251         }
 252         return false;
 253 }
 254 EXPORT_SYMBOL(rate_control_send_low);
 255
 256 static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
 257                                 int n_bitrates, u32 mask)
 258 {
 259         int j;
 260
 261         /* See whether the selected rate or anything below it is allowed. */
 262         for (j = rate->idx; j >= 0; j--) {
 263                 if (mask & (1 << j)) {
 264                         /* Okay, found a suitable rate. Use it. */
 265                         rate->idx = j;
 266                         return;
 267                 }
 268         }
 269
 270         /* Try to find a higher rate that would be allowed */
 271         for (j = rate->idx + 1; j < n_bitrates; j++) {
 272                 if (mask & (1 << j)) {
 273                         /* Okay, found a suitable rate. Use it. */
 274                         rate->idx = j;
 275                         return;
 276                 }
 277         }
 278
 279         /*
 280          * Uh.. No suitable rate exists. This should not really happen with
 281          * sane TX rate mask configurations. However, should someone manage to
 282          * configure supported rates and TX rate mask in incompatible way,
 283          * allow the frame to be transmitted with whatever the rate control
 284          * selected.
 285          */
 286 }
 287
 288 void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
 289                            struct sta_info *sta,
 290                            struct ieee80211_tx_rate_control *txrc)
 291 {
 292         struct rate_control_ref *ref = sdata->local->rate_ctrl;
 293         void *priv_sta = NULL;
 294         struct ieee80211_sta *ista = NULL;
 295         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 296         int i;
 297         u32 mask;
 298
 299         if (sta) {
 300                 ista = &sta->sta;
 301                 priv_sta = sta->rate_ctrl_priv;
 302         }
 303
 304         for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 305                 info->control.rates[i].idx = -1;
 306                 info->control.rates[i].flags = 0;
 307                 info->control.rates[i].count = 1;
 308         }
 309
 310         if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
 311                 return;
 312
 313         ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
 314
 315         /*
 316          * Try to enforce the rateidx mask the user wanted. skip this if the
 317          * default mask (allow all rates) is used to save some processing for
 318          * the common case.
 319          */
 320         mask = sdata->rc_rateidx_mask[info->band];
 321         if (mask != (1 << txrc->sband->n_bitrates) - 1) {
 322                 if (sta) {
 323                         /* Filter out rates that the STA does not support */
 324                         mask &= sta->sta.supp_rates[info->band];
 325                 }
 326                 /*
 327                  * Make sure the rate index selected for each TX rate is
 328                  * included in the configured mask and change the rate indexes
 329                  * if needed.
 330                  */
 331                 for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 332                         /* Skip invalid rates */
 333                         if (info->control.rates[i].idx < 0)
 334                                 break;
 335                         /* Rate masking supports only legacy rates for now */
 336                         if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS)
 337                                 continue;
 338                         rate_idx_match_mask(&info->control.rates[i],
 339                                             txrc->sband->n_bitrates, mask);
 340                 }
 341         }
 342
 343         BUG_ON(info->control.rates[0].idx < 0);
 344 }
 345
 346 struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
 347 {
 348         kref_get(&ref->kref);
 349         return ref;
 350 }
 351
 352 void rate_control_put(struct rate_control_ref *ref)
 353 {
 354         kref_put(&ref->kref, rate_control_release);
 355 }
 356
 357 int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
 358                                  const char *name)
 359 {
 360         struct rate_control_ref *ref, *old;
 361
 362         ASSERT_RTNL();
 363
 364         if (local->open_count)
 365                 return -EBUSY;
 366
 367         if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
 368                 if (WARN_ON(!local->ops->set_rts_threshold))
 369                         return -EINVAL;
 370                 return 0;
 371         }
 372
 373         ref = rate_control_alloc(name, local);
 374         if (!ref) {
 375                 wiphy_warn(local->hw.wiphy,
 376                            "Failed to select rate control algorithm\n");
 377                 return -ENOENT;
 378         }
 379
 380         old = local->rate_ctrl;
 381         local->rate_ctrl = ref;
 382         if (old) {
 383                 rate_control_put(old);
 384                 sta_info_flush(local, NULL);
 385         }
 386
 387         wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
 388                     ref->ops->name);
 389
 390         return 0;
 391 }
 392
 393 void rate_control_deinitialize(struct ieee80211_local *local)
 394 {
 395         struct rate_control_ref *ref;
 396
 397         ref = local->rate_ctrl;
 398
 399         if (!ref)
 400                 return;
 401
 402         local->rate_ctrl = NULL;
 403         rate_control_put(ref);
 404 }
 405