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         if (!name)
 107                 alg_name = ieee80211_default_rc_algo;
 108         else
 109                 alg_name = name;
 110
 111         ops = ieee80211_try_rate_control_ops_get(alg_name);
 112         if (!ops) {
 113                 request_module("rc80211_%s", alg_name);
 114                 ops = ieee80211_try_rate_control_ops_get(alg_name);
 115         }
 116         if (!ops && name)
 117                 /* try default if specific alg requested but not found */
 118                 ops = ieee80211_try_rate_control_ops_get(ieee80211_default_rc_algo);
 119
 120         /* try built-in one if specific alg requested but not found */
 121         if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
 122                 ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
 123
 124         return ops;
 125 }
 126
 127 static void ieee80211_rate_control_ops_put(struct rate_control_ops *ops)
 128 {
 129         module_put(ops->module);
 130 }
 131
 132 #ifdef CONFIG_MAC80211_DEBUGFS
 133 static ssize_t rcname_read(struct file *file, char __user *userbuf,
 134                            size_t count, loff_t *ppos)
 135 {
 136         struct rate_control_ref *ref = file->private_data;
 137         int len = strlen(ref->ops->name);
 138
 139         return simple_read_from_buffer(userbuf, count, ppos,
 140                                        ref->ops->name, len);
 141 }
 142
 143 static const struct file_operations rcname_ops = {
 144         .read = rcname_read,
 145         .open = mac80211_open_file_generic,
 146 };
 147 #endif
 148
 149 static struct rate_control_ref *rate_control_alloc(const char *name,
 150                                             struct ieee80211_local *local)
 151 {
 152         struct dentry *debugfsdir = NULL;
 153         struct rate_control_ref *ref;
 154
 155         ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
 156         if (!ref)
 157                 goto fail_ref;
 158         kref_init(&ref->kref);
 159         ref->local = local;
 160         ref->ops = ieee80211_rate_control_ops_get(name);
 161         if (!ref->ops)
 162                 goto fail_ops;
 163
 164 #ifdef CONFIG_MAC80211_DEBUGFS
 165         debugfsdir = debugfs_create_dir("rc", local->hw.wiphy->debugfsdir);
 166         local->debugfs.rcdir = debugfsdir;
 167         debugfs_create_file("name", 0400, debugfsdir, ref, &rcname_ops);
 168 #endif
 169
 170         ref->priv = ref->ops->alloc(&local->hw, debugfsdir);
 171         if (!ref->priv)
 172                 goto fail_priv;
 173         return ref;
 174
 175 fail_priv:
 176         ieee80211_rate_control_ops_put(ref->ops);
 177 fail_ops:
 178         kfree(ref);
 179 fail_ref:
 180         return NULL;
 181 }
 182
 183 static void rate_control_release(struct kref *kref)
 184 {
 185         struct rate_control_ref *ctrl_ref;
 186
 187         ctrl_ref = container_of(kref, struct rate_control_ref, kref);
 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(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) || !ieee80211_is_data(fc));
 209 }
 210
 211 static void rc_send_low_broadcast(s8 *idx, u32 basic_rates, u8 max_rate_idx)
 212 {
 213         u8 i;
 214
 215         if (basic_rates == 0)
 216                 return; /* assume basic rates unknown and accept rate */
 217         if (*idx < 0)
 218                 return;
 219         if (basic_rates & (1 << *idx))
 220                 return; /* selected rate is a basic rate */
 221
 222         for (i = *idx + 1; i <= max_rate_idx; i++) {
 223                 if (basic_rates & (1 << i)) {
 224                         *idx = i;
 225                         return;
 226                 }
 227         }
 228
 229         /* could not find a basic rate; use original selection */
 230 }
 231
 232 bool rate_control_send_low(struct ieee80211_sta *sta,
 233                            void *priv_sta,
 234                            struct ieee80211_tx_rate_control *txrc)
 235 {
 236         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 237
 238         if (!sta || !priv_sta || rc_no_data_or_no_ack(txrc)) {
 239                 info->control.rates[0].idx = rate_lowest_index(txrc->sband, sta);
 240                 info->control.rates[0].count =
 241                         (info->flags & IEEE80211_TX_CTL_NO_ACK) ?
 242                         1 : txrc->hw->max_rate_tries;
 243                 if (!sta && txrc->ap)
 244                         rc_send_low_broadcast(&info->control.rates[0].idx,
 245                                               txrc->bss_conf->basic_rates,
 246                                               txrc->sband->n_bitrates);
 247                 return true;
 248         }
 249         return false;
 250 }
 251 EXPORT_SYMBOL(rate_control_send_low);
 252
 253 static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
 254                                 int n_bitrates, u32 mask)
 255 {
 256         int j;
 257
 258         /* See whether the selected rate or anything below it is allowed. */
 259         for (j = rate->idx; j >= 0; j--) {
 260                 if (mask & (1 << j)) {
 261                         /* Okay, found a suitable rate. Use it. */
 262                         rate->idx = j;
 263                         return;
 264                 }
 265         }
 266
 267         /* Try to find a higher rate that would be allowed */
 268         for (j = rate->idx + 1; j < n_bitrates; j++) {
 269                 if (mask & (1 << j)) {
 270                         /* Okay, found a suitable rate. Use it. */
 271                         rate->idx = j;
 272                         return;
 273                 }
 274         }
 275
 276         /*
 277          * Uh.. No suitable rate exists. This should not really happen with
 278          * sane TX rate mask configurations. However, should someone manage to
 279          * configure supported rates and TX rate mask in incompatible way,
 280          * allow the frame to be transmitted with whatever the rate control
 281          * selected.
 282          */
 283 }
 284
 285 void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
 286                            struct sta_info *sta,
 287                            struct ieee80211_tx_rate_control *txrc)
 288 {
 289         struct rate_control_ref *ref = sdata->local->rate_ctrl;
 290         void *priv_sta = NULL;
 291         struct ieee80211_sta *ista = NULL;
 292         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 293         int i;
 294         u32 mask;
 295
 296         if (sta) {
 297                 ista = &sta->sta;
 298                 priv_sta = sta->rate_ctrl_priv;
 299         }
 300
 301         for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 302                 info->control.rates[i].idx = -1;
 303                 info->control.rates[i].flags = 0;
 304                 info->control.rates[i].count = 1;
 305         }
 306
 307         if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
 308                 return;
 309
 310         ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
 311
 312         /*
 313          * Try to enforce the rateidx mask the user wanted. skip this if the
 314          * default mask (allow all rates) is used to save some processing for
 315          * the common case.
 316          */
 317         mask = sdata->rc_rateidx_mask[info->band];
 318         if (mask != (1 << txrc->sband->n_bitrates) - 1) {
 319                 if (sta) {
 320                         /* Filter out rates that the STA does not support */
 321                         mask &= sta->sta.supp_rates[info->band];
 322                 }
 323                 /*
 324                  * Make sure the rate index selected for each TX rate is
 325                  * included in the configured mask and change the rate indexes
 326                  * if needed.
 327                  */
 328                 for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 329                         /* Rate masking supports only legacy rates for now */
 330                         if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS)
 331                                 continue;
 332                         rate_idx_match_mask(&info->control.rates[i],
 333                                             txrc->sband->n_bitrates, mask);
 334                 }
 335         }
 336
 337         BUG_ON(info->control.rates[0].idx < 0);
 338 }
 339
 340 struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
 341 {
 342         kref_get(&ref->kref);
 343         return ref;
 344 }
 345
 346 void rate_control_put(struct rate_control_ref *ref)
 347 {
 348         kref_put(&ref->kref, rate_control_release);
 349 }
 350
 351 int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
 352                                  const char *name)
 353 {
 354         struct rate_control_ref *ref, *old;
 355
 356         ASSERT_RTNL();
 357
 358         if (local->open_count)
 359                 return -EBUSY;
 360
 361         if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
 362                 if (WARN_ON(!local->ops->set_rts_threshold))
 363                         return -EINVAL;
 364                 return 0;
 365         }
 366
 367         ref = rate_control_alloc(name, local);
 368         if (!ref) {
 369                 printk(KERN_WARNING "%s: Failed to select rate control "
 370                        "algorithm\n", wiphy_name(local->hw.wiphy));
 371                 return -ENOENT;
 372         }
 373
 374         old = local->rate_ctrl;
 375         local->rate_ctrl = ref;
 376         if (old) {
 377                 rate_control_put(old);
 378                 sta_info_flush(local, NULL);
 379         }
 380
 381         printk(KERN_DEBUG "%s: Selected rate control "
 382                "algorithm '%s'\n", wiphy_name(local->hw.wiphy),
 383                ref->ops->name);
 384
 385         return 0;
 386 }
 387
 388 void rate_control_deinitialize(struct ieee80211_local *local)
 389 {
 390         struct rate_control_ref *ref;
 391
 392         ref = local->rate_ctrl;
 393
 394         if (!ref)
 395                 return;
 396
 397         local->rate_ctrl = NULL;
 398         rate_control_put(ref);
 399 }
 400