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 };
 149 #endif
 150
 151 static struct rate_control_ref *rate_control_alloc(const char *name,
 152                                             struct ieee80211_local *local)
 153 {
 154         struct dentry *debugfsdir = NULL;
 155         struct rate_control_ref *ref;
 156
 157         ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
 158         if (!ref)
 159                 goto fail_ref;
 160         kref_init(&ref->kref);
 161         ref->local = local;
 162         ref->ops = ieee80211_rate_control_ops_get(name);
 163         if (!ref->ops)
 164                 goto fail_ops;
 165
 166 #ifdef CONFIG_MAC80211_DEBUGFS
 167         debugfsdir = debugfs_create_dir("rc", local->hw.wiphy->debugfsdir);
 168         local->debugfs.rcdir = debugfsdir;
 169         debugfs_create_file("name", 0400, debugfsdir, ref, &rcname_ops);
 170 #endif
 171
 172         ref->priv = ref->ops->alloc(&local->hw, debugfsdir);
 173         if (!ref->priv)
 174                 goto fail_priv;
 175         return ref;
 176
 177 fail_priv:
 178         ieee80211_rate_control_ops_put(ref->ops);
 179 fail_ops:
 180         kfree(ref);
 181 fail_ref:
 182         return NULL;
 183 }
 184
 185 static void rate_control_release(struct kref *kref)
 186 {
 187         struct rate_control_ref *ctrl_ref;
 188
 189         ctrl_ref = container_of(kref, struct rate_control_ref, kref);
 190         ctrl_ref->ops->free(ctrl_ref->priv);
 191
 192 #ifdef CONFIG_MAC80211_DEBUGFS
 193         debugfs_remove_recursive(ctrl_ref->local->debugfs.rcdir);
 194         ctrl_ref->local->debugfs.rcdir = NULL;
 195 #endif
 196
 197         ieee80211_rate_control_ops_put(ctrl_ref->ops);
 198         kfree(ctrl_ref);
 199 }
 200
 201 static bool rc_no_data_or_no_ack(struct ieee80211_tx_rate_control *txrc)
 202 {
 203         struct sk_buff *skb = txrc->skb;
 204         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 205         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 206         __le16 fc;
 207
 208         fc = hdr->frame_control;
 209
 210         return ((info->flags & IEEE80211_TX_CTL_NO_ACK) || !ieee80211_is_data(fc));
 211 }
 212
 213 static void rc_send_low_broadcast(s8 *idx, u32 basic_rates, u8 max_rate_idx)
 214 {
 215         u8 i;
 216
 217         if (basic_rates == 0)
 218                 return; /* assume basic rates unknown and accept rate */
 219         if (*idx < 0)
 220                 return;
 221         if (basic_rates & (1 << *idx))
 222                 return; /* selected rate is a basic rate */
 223
 224         for (i = *idx + 1; i <= max_rate_idx; i++) {
 225                 if (basic_rates & (1 << i)) {
 226                         *idx = i;
 227                         return;
 228                 }
 229         }
 230
 231         /* could not find a basic rate; use original selection */
 232 }
 233
 234 bool rate_control_send_low(struct ieee80211_sta *sta,
 235                            void *priv_sta,
 236                            struct ieee80211_tx_rate_control *txrc)
 237 {
 238         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 239
 240         if (!sta || !priv_sta || rc_no_data_or_no_ack(txrc)) {
 241                 info->control.rates[0].idx = rate_lowest_index(txrc->sband, sta);
 242                 info->control.rates[0].count =
 243                         (info->flags & IEEE80211_TX_CTL_NO_ACK) ?
 244                         1 : txrc->hw->max_rate_tries;
 245                 if (!sta && txrc->ap)
 246                         rc_send_low_broadcast(&info->control.rates[0].idx,
 247                                               txrc->bss_conf->basic_rates,
 248                                               txrc->sband->n_bitrates);
 249                 return true;
 250         }
 251         return false;
 252 }
 253 EXPORT_SYMBOL(rate_control_send_low);
 254
 255 static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
 256                                 int n_bitrates, u32 mask)
 257 {
 258         int j;
 259
 260         /* See whether the selected rate or anything below it is allowed. */
 261         for (j = rate->idx; j >= 0; j--) {
 262                 if (mask & (1 << j)) {
 263                         /* Okay, found a suitable rate. Use it. */
 264                         rate->idx = j;
 265                         return;
 266                 }
 267         }
 268
 269         /* Try to find a higher rate that would be allowed */
 270         for (j = rate->idx + 1; j < n_bitrates; j++) {
 271                 if (mask & (1 << j)) {
 272                         /* Okay, found a suitable rate. Use it. */
 273                         rate->idx = j;
 274                         return;
 275                 }
 276         }
 277
 278         /*
 279          * Uh.. No suitable rate exists. This should not really happen with
 280          * sane TX rate mask configurations. However, should someone manage to
 281          * configure supported rates and TX rate mask in incompatible way,
 282          * allow the frame to be transmitted with whatever the rate control
 283          * selected.
 284          */
 285 }
 286
 287 void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
 288                            struct sta_info *sta,
 289                            struct ieee80211_tx_rate_control *txrc)
 290 {
 291         struct rate_control_ref *ref = sdata->local->rate_ctrl;
 292         void *priv_sta = NULL;
 293         struct ieee80211_sta *ista = NULL;
 294         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 295         int i;
 296         u32 mask;
 297
 298         if (sta) {
 299                 ista = &sta->sta;
 300                 priv_sta = sta->rate_ctrl_priv;
 301         }
 302
 303         for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 304                 info->control.rates[i].idx = -1;
 305                 info->control.rates[i].flags = 0;
 306                 info->control.rates[i].count = 1;
 307         }
 308
 309         if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
 310                 return;
 311
 312         ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
 313
 314         /*
 315          * Try to enforce the rateidx mask the user wanted. skip this if the
 316          * default mask (allow all rates) is used to save some processing for
 317          * the common case.
 318          */
 319         mask = sdata->rc_rateidx_mask[info->band];
 320         if (mask != (1 << txrc->sband->n_bitrates) - 1) {
 321                 if (sta) {
 322                         /* Filter out rates that the STA does not support */
 323                         mask &= sta->sta.supp_rates[info->band];
 324                 }
 325                 /*
 326                  * Make sure the rate index selected for each TX rate is
 327                  * included in the configured mask and change the rate indexes
 328                  * if needed.
 329                  */
 330                 for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 331                         /* Rate masking supports only legacy rates for now */
 332                         if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS)
 333                                 continue;
 334                         rate_idx_match_mask(&info->control.rates[i],
 335                                             txrc->sband->n_bitrates, mask);
 336                 }
 337         }
 338
 339         BUG_ON(info->control.rates[0].idx < 0);
 340 }
 341
 342 struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
 343 {
 344         kref_get(&ref->kref);
 345         return ref;
 346 }
 347
 348 void rate_control_put(struct rate_control_ref *ref)
 349 {
 350         kref_put(&ref->kref, rate_control_release);
 351 }
 352
 353 int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
 354                                  const char *name)
 355 {
 356         struct rate_control_ref *ref, *old;
 357
 358         ASSERT_RTNL();
 359
 360         if (local->open_count)
 361                 return -EBUSY;
 362
 363         if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
 364                 if (WARN_ON(!local->ops->set_rts_threshold))
 365                         return -EINVAL;
 366                 return 0;
 367         }
 368
 369         ref = rate_control_alloc(name, local);
 370         if (!ref) {
 371                 printk(KERN_WARNING "%s: Failed to select rate control "
 372                        "algorithm\n", wiphy_name(local->hw.wiphy));
 373                 return -ENOENT;
 374         }
 375
 376         old = local->rate_ctrl;
 377         local->rate_ctrl = ref;
 378         if (old) {
 379                 rate_control_put(old);
 380                 sta_info_flush(local, NULL);
 381         }
 382
 383         printk(KERN_DEBUG "%s: Selected rate control "
 384                "algorithm '%s'\n", wiphy_name(local->hw.wiphy),
 385                ref->ops->name);
 386
 387         return 0;
 388 }
 389
 390 void rate_control_deinitialize(struct ieee80211_local *local)
 391 {
 392         struct rate_control_ref *ref;
 393
 394         ref = local->rate_ctrl;
 395
 396         if (!ref)
 397                 return;
 398
 399         local->rate_ctrl = NULL;
 400         rate_control_put(ref);
 401 }
 402