linux/net/mac80211/rate.c
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   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
  19struct rate_control_alg {
  20        struct list_head list;
  21        struct rate_control_ops *ops;
  22};
  23
  24static LIST_HEAD(rate_ctrl_algs);
  25static DEFINE_MUTEX(rate_ctrl_mutex);
  26
  27static char *ieee80211_default_rc_algo = CONFIG_MAC80211_RC_DEFAULT;
  28module_param(ieee80211_default_rc_algo, charp, 0644);
  29MODULE_PARM_DESC(ieee80211_default_rc_algo,
  30                 "Default rate control algorithm for mac80211 to use");
  31
  32int 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}
  61EXPORT_SYMBOL(ieee80211_rate_control_register);
  62
  63void 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}
  77EXPORT_SYMBOL(ieee80211_rate_control_unregister);
  78
  79static struct rate_control_ops *
  80ieee80211_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. */
 101static struct rate_control_ops *
 102ieee80211_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
 130static void ieee80211_rate_control_ops_put(struct rate_control_ops *ops)
 131{
 132        module_put(ops->module);
 133}
 134
 135#ifdef CONFIG_MAC80211_DEBUGFS
 136static 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
 146static const struct file_operations rcname_ops = {
 147        .read = rcname_read,
 148        .open = simple_open,
 149        .llseek = default_llseek,
 150};
 151#endif
 152
 153static 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
 178fail_priv:
 179        ieee80211_rate_control_ops_put(ref->ops);
 180fail_ops:
 181        kfree(ref);
 182fail_ref:
 183        return NULL;
 184}
 185
 186static 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
 199static 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
 213static 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
 235static inline s8
 236rate_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
 256bool 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}
 290EXPORT_SYMBOL(rate_control_send_low);
 291
 292static 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
 317static 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
 357static 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->channel_type == NL80211_CHAN_NO_HT)
 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->channel_type == NL80211_CHAN_HT40MINUS) ||
 412                    (txrc->bss_conf->channel_type == NL80211_CHAN_HT40PLUS))
 413                        alt_rate.flags |= IEEE80211_TX_RC_40_MHZ_WIDTH;
 414
 415                if (rate_idx_match_mcs_mask(&alt_rate, mcs_mask)) {
 416                        *rate = alt_rate;
 417                        return;
 418                }
 419        }
 420
 421        /*
 422         * Uh.. No suitable rate exists. This should not really happen with
 423         * sane TX rate mask configurations. However, should someone manage to
 424         * configure supported rates and TX rate mask in incompatible way,
 425         * allow the frame to be transmitted with whatever the rate control
 426         * selected.
 427         */
 428}
 429
 430void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
 431                           struct sta_info *sta,
 432                           struct ieee80211_tx_rate_control *txrc)
 433{
 434        struct rate_control_ref *ref = sdata->local->rate_ctrl;
 435        void *priv_sta = NULL;
 436        struct ieee80211_sta *ista = NULL;
 437        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 438        int i;
 439        u32 mask;
 440        u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN];
 441
 442        if (sta && test_sta_flag(sta, WLAN_STA_RATE_CONTROL)) {
 443                ista = &sta->sta;
 444                priv_sta = sta->rate_ctrl_priv;
 445        }
 446
 447        for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 448                info->control.rates[i].idx = -1;
 449                info->control.rates[i].flags = 0;
 450                info->control.rates[i].count = 0;
 451        }
 452
 453        if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
 454                return;
 455
 456        ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
 457
 458        /*
 459         * Try to enforce the rateidx mask the user wanted. skip this if the
 460         * default mask (allow all rates) is used to save some processing for
 461         * the common case.
 462         */
 463        mask = sdata->rc_rateidx_mask[info->band];
 464        memcpy(mcs_mask, sdata->rc_rateidx_mcs_mask[info->band],
 465               sizeof(mcs_mask));
 466        if (mask != (1 << txrc->sband->n_bitrates) - 1) {
 467                if (sta) {
 468                        /* Filter out rates that the STA does not support */
 469                        mask &= sta->sta.supp_rates[info->band];
 470                        for (i = 0; i < sizeof(mcs_mask); i++)
 471                                mcs_mask[i] &= sta->sta.ht_cap.mcs.rx_mask[i];
 472                }
 473                /*
 474                 * Make sure the rate index selected for each TX rate is
 475                 * included in the configured mask and change the rate indexes
 476                 * if needed.
 477                 */
 478                for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 479                        /* Skip invalid rates */
 480                        if (info->control.rates[i].idx < 0)
 481                                break;
 482                        rate_idx_match_mask(&info->control.rates[i], txrc,
 483                                            mask, mcs_mask);
 484                }
 485        }
 486
 487        BUG_ON(info->control.rates[0].idx < 0);
 488}
 489
 490int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
 491                                 const char *name)
 492{
 493        struct rate_control_ref *ref;
 494
 495        ASSERT_RTNL();
 496
 497        if (local->open_count)
 498                return -EBUSY;
 499
 500        if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
 501                if (WARN_ON(!local->ops->set_rts_threshold))
 502                        return -EINVAL;
 503                return 0;
 504        }
 505
 506        ref = rate_control_alloc(name, local);
 507        if (!ref) {
 508                wiphy_warn(local->hw.wiphy,
 509                           "Failed to select rate control algorithm\n");
 510                return -ENOENT;
 511        }
 512
 513        WARN_ON(local->rate_ctrl);
 514        local->rate_ctrl = ref;
 515
 516        wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
 517                    ref->ops->name);
 518
 519        return 0;
 520}
 521
 522void rate_control_deinitialize(struct ieee80211_local *local)
 523{
 524        struct rate_control_ref *ref;
 525
 526        ref = local->rate_ctrl;
 527
 528        if (!ref)
 529                return;
 530
 531        local->rate_ctrl = NULL;
 532        rate_control_free(ref);
 533}
 534
 535
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