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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 "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,
215                                   struct ieee80211_supported_band *sband)
216 {
217         u8 i;
218 
219         if (basic_rates == 0)
220                 return; /* assume basic rates unknown and accept rate */
221         if (*idx < 0)
222                 return;
223         if (basic_rates & (1 << *idx))
224                 return; /* selected rate is a basic rate */
225 
226         for (i = *idx + 1; i <= sband->n_bitrates; i++) {
227                 if (basic_rates & (1 << i)) {
228                         *idx = i;
229                         return;
230                 }
231         }
232 
233         /* could not find a basic rate; use original selection */
234 }
235 
236 bool rate_control_send_low(struct ieee80211_sta *sta,
237                            void *priv_sta,
238                            struct ieee80211_tx_rate_control *txrc)
239 {
240         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
241         struct ieee80211_supported_band *sband = txrc->sband;
242         int mcast_rate;
243 
244         if (!sta || !priv_sta || rc_no_data_or_no_ack(txrc)) {
245                 info->control.rates[0].idx = rate_lowest_index(txrc->sband, sta);
246                 info->control.rates[0].count =
247                         (info->flags & IEEE80211_TX_CTL_NO_ACK) ?
248                         1 : txrc->hw->max_rate_tries;
249                 if (!sta && txrc->bss) {
250                         mcast_rate = txrc->bss_conf->mcast_rate[sband->band];
251                         if (mcast_rate > 0) {
252                                 info->control.rates[0].idx = mcast_rate - 1;
253                                 return true;
254                         }
255 
256                         rc_send_low_broadcast(&info->control.rates[0].idx,
257                                               txrc->bss_conf->basic_rates,
258                                               sband);
259                 }
260                 return true;
261         }
262         return false;
263 }
264 EXPORT_SYMBOL(rate_control_send_low);
265 
266 static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
267                                 int n_bitrates, u32 mask)
268 {
269         int j;
270 
271         /* See whether the selected rate or anything below it is allowed. */
272         for (j = rate->idx; j >= 0; j--) {
273                 if (mask & (1 << j)) {
274                         /* Okay, found a suitable rate. Use it. */
275                         rate->idx = j;
276                         return;
277                 }
278         }
279 
280         /* Try to find a higher rate that would be allowed */
281         for (j = rate->idx + 1; j < n_bitrates; j++) {
282                 if (mask & (1 << j)) {
283                         /* Okay, found a suitable rate. Use it. */
284                         rate->idx = j;
285                         return;
286                 }
287         }
288 
289         /*
290          * Uh.. No suitable rate exists. This should not really happen with
291          * sane TX rate mask configurations. However, should someone manage to
292          * configure supported rates and TX rate mask in incompatible way,
293          * allow the frame to be transmitted with whatever the rate control
294          * selected.
295          */
296 }
297 
298 void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
299                            struct sta_info *sta,
300                            struct ieee80211_tx_rate_control *txrc)
301 {
302         struct rate_control_ref *ref = sdata->local->rate_ctrl;
303         void *priv_sta = NULL;
304         struct ieee80211_sta *ista = NULL;
305         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
306         int i;
307         u32 mask;
308 
309         if (sta) {
310                 ista = &sta->sta;
311                 priv_sta = sta->rate_ctrl_priv;
312         }
313 
314         for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
315                 info->control.rates[i].idx = -1;
316                 info->control.rates[i].flags = 0;
317                 info->control.rates[i].count = 0;
318         }
319 
320         if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
321                 return;
322 
323         ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
324 
325         /*
326          * Try to enforce the rateidx mask the user wanted. skip this if the
327          * default mask (allow all rates) is used to save some processing for
328          * the common case.
329          */
330         mask = sdata->rc_rateidx_mask[info->band];
331         if (mask != (1 << txrc->sband->n_bitrates) - 1) {
332                 if (sta) {
333                         /* Filter out rates that the STA does not support */
334                         mask &= sta->sta.supp_rates[info->band];
335                 }
336                 /*
337                  * Make sure the rate index selected for each TX rate is
338                  * included in the configured mask and change the rate indexes
339                  * if needed.
340                  */
341                 for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
342                         /* Skip invalid rates */
343                         if (info->control.rates[i].idx < 0)
344                                 break;
345                         /* Rate masking supports only legacy rates for now */
346                         if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS)
347                                 continue;
348                         rate_idx_match_mask(&info->control.rates[i],
349                                             txrc->sband->n_bitrates, mask);
350                 }
351         }
352 
353         BUG_ON(info->control.rates[0].idx < 0);
354 }
355 
356 struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
357 {
358         kref_get(&ref->kref);
359         return ref;
360 }
361 
362 void rate_control_put(struct rate_control_ref *ref)
363 {
364         kref_put(&ref->kref, rate_control_release);
365 }
366 
367 int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
368                                  const char *name)
369 {
370         struct rate_control_ref *ref, *old;
371 
372         ASSERT_RTNL();
373 
374         if (local->open_count)
375                 return -EBUSY;
376 
377         if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
378                 if (WARN_ON(!local->ops->set_rts_threshold))
379                         return -EINVAL;
380                 return 0;
381         }
382 
383         ref = rate_control_alloc(name, local);
384         if (!ref) {
385                 wiphy_warn(local->hw.wiphy,
386                            "Failed to select rate control algorithm\n");
387                 return -ENOENT;
388         }
389 
390         old = local->rate_ctrl;
391         local->rate_ctrl = ref;
392         if (old) {
393                 rate_control_put(old);
394                 sta_info_flush(local, NULL);
395         }
396 
397         wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
398                     ref->ops->name);
399 
400         return 0;
401 }
402 
403 void rate_control_deinitialize(struct ieee80211_local *local)
404 {
405         struct rate_control_ref *ref;
406 
407         ref = local->rate_ctrl;
408 
409         if (!ref)
410                 return;
411 
412         local->rate_ctrl = NULL;
413         rate_control_put(ref);
414 }
415 
416 

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