kprobes: remove redundant config check
[linux-2.6] / 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 "rate.h"
14 #include "ieee80211_i.h"
15
16 struct rate_control_alg {
17         struct list_head list;
18         struct rate_control_ops *ops;
19 };
20
21 static LIST_HEAD(rate_ctrl_algs);
22 static DEFINE_MUTEX(rate_ctrl_mutex);
23
24 static char *ieee80211_default_rc_algo = CONFIG_MAC80211_RC_DEFAULT;
25 module_param(ieee80211_default_rc_algo, charp, 0644);
26 MODULE_PARM_DESC(ieee80211_default_rc_algo,
27                  "Default rate control algorithm for mac80211 to use");
28
29 int ieee80211_rate_control_register(struct rate_control_ops *ops)
30 {
31         struct rate_control_alg *alg;
32
33         if (!ops->name)
34                 return -EINVAL;
35
36         mutex_lock(&rate_ctrl_mutex);
37         list_for_each_entry(alg, &rate_ctrl_algs, list) {
38                 if (!strcmp(alg->ops->name, ops->name)) {
39                         /* don't register an algorithm twice */
40                         WARN_ON(1);
41                         mutex_unlock(&rate_ctrl_mutex);
42                         return -EALREADY;
43                 }
44         }
45
46         alg = kzalloc(sizeof(*alg), GFP_KERNEL);
47         if (alg == NULL) {
48                 mutex_unlock(&rate_ctrl_mutex);
49                 return -ENOMEM;
50         }
51         alg->ops = ops;
52
53         list_add_tail(&alg->list, &rate_ctrl_algs);
54         mutex_unlock(&rate_ctrl_mutex);
55
56         return 0;
57 }
58 EXPORT_SYMBOL(ieee80211_rate_control_register);
59
60 void ieee80211_rate_control_unregister(struct rate_control_ops *ops)
61 {
62         struct rate_control_alg *alg;
63
64         mutex_lock(&rate_ctrl_mutex);
65         list_for_each_entry(alg, &rate_ctrl_algs, list) {
66                 if (alg->ops == ops) {
67                         list_del(&alg->list);
68                         kfree(alg);
69                         break;
70                 }
71         }
72         mutex_unlock(&rate_ctrl_mutex);
73 }
74 EXPORT_SYMBOL(ieee80211_rate_control_unregister);
75
76 static struct rate_control_ops *
77 ieee80211_try_rate_control_ops_get(const char *name)
78 {
79         struct rate_control_alg *alg;
80         struct rate_control_ops *ops = NULL;
81
82         if (!name)
83                 return NULL;
84
85         mutex_lock(&rate_ctrl_mutex);
86         list_for_each_entry(alg, &rate_ctrl_algs, list) {
87                 if (!strcmp(alg->ops->name, name))
88                         if (try_module_get(alg->ops->module)) {
89                                 ops = alg->ops;
90                                 break;
91                         }
92         }
93         mutex_unlock(&rate_ctrl_mutex);
94         return ops;
95 }
96
97 /* Get the rate control algorithm. */
98 static struct rate_control_ops *
99 ieee80211_rate_control_ops_get(const char *name)
100 {
101         struct rate_control_ops *ops;
102         const char *alg_name;
103
104         if (!name)
105                 alg_name = ieee80211_default_rc_algo;
106         else
107                 alg_name = name;
108
109         ops = ieee80211_try_rate_control_ops_get(alg_name);
110         if (!ops) {
111                 request_module("rc80211_%s", alg_name);
112                 ops = ieee80211_try_rate_control_ops_get(alg_name);
113         }
114         if (!ops && name)
115                 /* try default if specific alg requested but not found */
116                 ops = ieee80211_try_rate_control_ops_get(ieee80211_default_rc_algo);
117
118         /* try built-in one if specific alg requested but not found */
119         if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
120                 ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
121
122         return ops;
123 }
124
125 static void ieee80211_rate_control_ops_put(struct rate_control_ops *ops)
126 {
127         module_put(ops->module);
128 }
129
130 struct rate_control_ref *rate_control_alloc(const char *name,
131                                             struct ieee80211_local *local)
132 {
133         struct rate_control_ref *ref;
134
135         ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
136         if (!ref)
137                 goto fail_ref;
138         kref_init(&ref->kref);
139         ref->ops = ieee80211_rate_control_ops_get(name);
140         if (!ref->ops)
141                 goto fail_ops;
142         ref->priv = ref->ops->alloc(local);
143         if (!ref->priv)
144                 goto fail_priv;
145         return ref;
146
147 fail_priv:
148         ieee80211_rate_control_ops_put(ref->ops);
149 fail_ops:
150         kfree(ref);
151 fail_ref:
152         return NULL;
153 }
154
155 static void rate_control_release(struct kref *kref)
156 {
157         struct rate_control_ref *ctrl_ref;
158
159         ctrl_ref = container_of(kref, struct rate_control_ref, kref);
160         ctrl_ref->ops->free(ctrl_ref->priv);
161         ieee80211_rate_control_ops_put(ctrl_ref->ops);
162         kfree(ctrl_ref);
163 }
164
165 void rate_control_get_rate(struct net_device *dev,
166                            struct ieee80211_supported_band *sband,
167                            struct sk_buff *skb,
168                            struct rate_selection *sel)
169 {
170         struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
171         struct rate_control_ref *ref = local->rate_ctrl;
172         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
173         struct sta_info *sta;
174         int i;
175
176         rcu_read_lock();
177         sta = sta_info_get(local, hdr->addr1);
178
179         sel->rate_idx = -1;
180         sel->nonerp_idx = -1;
181         sel->probe_idx = -1;
182
183         ref->ops->get_rate(ref->priv, dev, sband, skb, sel);
184
185         BUG_ON(sel->rate_idx < 0);
186
187         /* Select a non-ERP backup rate. */
188         if (sel->nonerp_idx < 0) {
189                 for (i = 0; i < sband->n_bitrates; i++) {
190                         struct ieee80211_rate *rate = &sband->bitrates[i];
191                         if (sband->bitrates[sel->rate_idx].bitrate < rate->bitrate)
192                                 break;
193
194                         if (rate_supported(sta, sband->band, i) &&
195                             !(rate->flags & IEEE80211_RATE_ERP_G))
196                                 sel->nonerp_idx = i;
197                 }
198         }
199
200         rcu_read_unlock();
201 }
202
203 struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
204 {
205         kref_get(&ref->kref);
206         return ref;
207 }
208
209 void rate_control_put(struct rate_control_ref *ref)
210 {
211         kref_put(&ref->kref, rate_control_release);
212 }
213
214 int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
215                                  const char *name)
216 {
217         struct rate_control_ref *ref, *old;
218
219         ASSERT_RTNL();
220         if (local->open_count || netif_running(local->mdev))
221                 return -EBUSY;
222
223         ref = rate_control_alloc(name, local);
224         if (!ref) {
225                 printk(KERN_WARNING "%s: Failed to select rate control "
226                        "algorithm\n", wiphy_name(local->hw.wiphy));
227                 return -ENOENT;
228         }
229
230         old = local->rate_ctrl;
231         local->rate_ctrl = ref;
232         if (old) {
233                 rate_control_put(old);
234                 sta_info_flush(local, NULL);
235         }
236
237         printk(KERN_DEBUG "%s: Selected rate control "
238                "algorithm '%s'\n", wiphy_name(local->hw.wiphy),
239                ref->ops->name);
240
241
242         return 0;
243 }
244
245 void rate_control_deinitialize(struct ieee80211_local *local)
246 {
247         struct rate_control_ref *ref;
248
249         ref = local->rate_ctrl;
250         local->rate_ctrl = NULL;
251         rate_control_put(ref);
252 }
253