This source file includes following definitions.
- tcp_ca_find
- tcp_ca_find_autoload
- tcp_ca_find_key
- tcp_register_congestion_control
- tcp_unregister_congestion_control
- tcp_ca_get_key_by_name
- tcp_ca_get_name_by_key
- tcp_assign_congestion_control
- tcp_init_congestion_control
- tcp_reinit_congestion_control
- tcp_cleanup_congestion_control
- tcp_set_default_congestion_control
- tcp_congestion_default
- tcp_get_available_congestion_control
- tcp_get_default_congestion_control
- tcp_get_allowed_congestion_control
- tcp_set_allowed_congestion_control
- tcp_set_congestion_control
- tcp_slow_start
- tcp_cong_avoid_ai
- tcp_reno_cong_avoid
- tcp_reno_ssthresh
- tcp_reno_undo_cwnd
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9
10 #define pr_fmt(fmt) "TCP: " fmt
11
12 #include <linux/module.h>
13 #include <linux/mm.h>
14 #include <linux/types.h>
15 #include <linux/list.h>
16 #include <linux/gfp.h>
17 #include <linux/jhash.h>
18 #include <net/tcp.h>
19
20 static DEFINE_SPINLOCK(tcp_cong_list_lock);
21 static LIST_HEAD(tcp_cong_list);
22
23
24 static struct tcp_congestion_ops *tcp_ca_find(const char *name)
25 {
26 struct tcp_congestion_ops *e;
27
28 list_for_each_entry_rcu(e, &tcp_cong_list, list) {
29 if (strcmp(e->name, name) == 0)
30 return e;
31 }
32
33 return NULL;
34 }
35
36
37 static struct tcp_congestion_ops *tcp_ca_find_autoload(struct net *net,
38 const char *name)
39 {
40 struct tcp_congestion_ops *ca = tcp_ca_find(name);
41
42 #ifdef CONFIG_MODULES
43 if (!ca && capable(CAP_NET_ADMIN)) {
44 rcu_read_unlock();
45 request_module("tcp_%s", name);
46 rcu_read_lock();
47 ca = tcp_ca_find(name);
48 }
49 #endif
50 return ca;
51 }
52
53
54 struct tcp_congestion_ops *tcp_ca_find_key(u32 key)
55 {
56 struct tcp_congestion_ops *e;
57
58 list_for_each_entry_rcu(e, &tcp_cong_list, list) {
59 if (e->key == key)
60 return e;
61 }
62
63 return NULL;
64 }
65
66
67
68
69
70 int tcp_register_congestion_control(struct tcp_congestion_ops *ca)
71 {
72 int ret = 0;
73
74
75 if (!ca->ssthresh || !ca->undo_cwnd ||
76 !(ca->cong_avoid || ca->cong_control)) {
77 pr_err("%s does not implement required ops\n", ca->name);
78 return -EINVAL;
79 }
80
81 ca->key = jhash(ca->name, sizeof(ca->name), strlen(ca->name));
82
83 spin_lock(&tcp_cong_list_lock);
84 if (ca->key == TCP_CA_UNSPEC || tcp_ca_find_key(ca->key)) {
85 pr_notice("%s already registered or non-unique key\n",
86 ca->name);
87 ret = -EEXIST;
88 } else {
89 list_add_tail_rcu(&ca->list, &tcp_cong_list);
90 pr_debug("%s registered\n", ca->name);
91 }
92 spin_unlock(&tcp_cong_list_lock);
93
94 return ret;
95 }
96 EXPORT_SYMBOL_GPL(tcp_register_congestion_control);
97
98
99
100
101
102
103
104 void tcp_unregister_congestion_control(struct tcp_congestion_ops *ca)
105 {
106 spin_lock(&tcp_cong_list_lock);
107 list_del_rcu(&ca->list);
108 spin_unlock(&tcp_cong_list_lock);
109
110
111
112
113
114
115
116
117 synchronize_rcu();
118 }
119 EXPORT_SYMBOL_GPL(tcp_unregister_congestion_control);
120
121 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca)
122 {
123 const struct tcp_congestion_ops *ca;
124 u32 key = TCP_CA_UNSPEC;
125
126 might_sleep();
127
128 rcu_read_lock();
129 ca = tcp_ca_find_autoload(net, name);
130 if (ca) {
131 key = ca->key;
132 *ecn_ca = ca->flags & TCP_CONG_NEEDS_ECN;
133 }
134 rcu_read_unlock();
135
136 return key;
137 }
138 EXPORT_SYMBOL_GPL(tcp_ca_get_key_by_name);
139
140 char *tcp_ca_get_name_by_key(u32 key, char *buffer)
141 {
142 const struct tcp_congestion_ops *ca;
143 char *ret = NULL;
144
145 rcu_read_lock();
146 ca = tcp_ca_find_key(key);
147 if (ca)
148 ret = strncpy(buffer, ca->name,
149 TCP_CA_NAME_MAX);
150 rcu_read_unlock();
151
152 return ret;
153 }
154 EXPORT_SYMBOL_GPL(tcp_ca_get_name_by_key);
155
156
157 void tcp_assign_congestion_control(struct sock *sk)
158 {
159 struct net *net = sock_net(sk);
160 struct inet_connection_sock *icsk = inet_csk(sk);
161 const struct tcp_congestion_ops *ca;
162
163 rcu_read_lock();
164 ca = rcu_dereference(net->ipv4.tcp_congestion_control);
165 if (unlikely(!try_module_get(ca->owner)))
166 ca = &tcp_reno;
167 icsk->icsk_ca_ops = ca;
168 rcu_read_unlock();
169
170 memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
171 if (ca->flags & TCP_CONG_NEEDS_ECN)
172 INET_ECN_xmit(sk);
173 else
174 INET_ECN_dontxmit(sk);
175 }
176
177 void tcp_init_congestion_control(struct sock *sk)
178 {
179 const struct inet_connection_sock *icsk = inet_csk(sk);
180
181 tcp_sk(sk)->prior_ssthresh = 0;
182 if (icsk->icsk_ca_ops->init)
183 icsk->icsk_ca_ops->init(sk);
184 if (tcp_ca_needs_ecn(sk))
185 INET_ECN_xmit(sk);
186 else
187 INET_ECN_dontxmit(sk);
188 }
189
190 static void tcp_reinit_congestion_control(struct sock *sk,
191 const struct tcp_congestion_ops *ca)
192 {
193 struct inet_connection_sock *icsk = inet_csk(sk);
194
195 tcp_cleanup_congestion_control(sk);
196 icsk->icsk_ca_ops = ca;
197 icsk->icsk_ca_setsockopt = 1;
198 memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
199
200 if (sk->sk_state != TCP_CLOSE)
201 tcp_init_congestion_control(sk);
202 }
203
204
205 void tcp_cleanup_congestion_control(struct sock *sk)
206 {
207 struct inet_connection_sock *icsk = inet_csk(sk);
208
209 if (icsk->icsk_ca_ops->release)
210 icsk->icsk_ca_ops->release(sk);
211 module_put(icsk->icsk_ca_ops->owner);
212 }
213
214
215 int tcp_set_default_congestion_control(struct net *net, const char *name)
216 {
217 struct tcp_congestion_ops *ca;
218 const struct tcp_congestion_ops *prev;
219 int ret;
220
221 rcu_read_lock();
222 ca = tcp_ca_find_autoload(net, name);
223 if (!ca) {
224 ret = -ENOENT;
225 } else if (!try_module_get(ca->owner)) {
226 ret = -EBUSY;
227 } else {
228 prev = xchg(&net->ipv4.tcp_congestion_control, ca);
229 if (prev)
230 module_put(prev->owner);
231
232 ca->flags |= TCP_CONG_NON_RESTRICTED;
233 ret = 0;
234 }
235 rcu_read_unlock();
236
237 return ret;
238 }
239
240
241 static int __init tcp_congestion_default(void)
242 {
243 return tcp_set_default_congestion_control(&init_net,
244 CONFIG_DEFAULT_TCP_CONG);
245 }
246 late_initcall(tcp_congestion_default);
247
248
249 void tcp_get_available_congestion_control(char *buf, size_t maxlen)
250 {
251 struct tcp_congestion_ops *ca;
252 size_t offs = 0;
253
254 rcu_read_lock();
255 list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
256 offs += snprintf(buf + offs, maxlen - offs,
257 "%s%s",
258 offs == 0 ? "" : " ", ca->name);
259 }
260 rcu_read_unlock();
261 }
262
263
264 void tcp_get_default_congestion_control(struct net *net, char *name)
265 {
266 const struct tcp_congestion_ops *ca;
267
268 rcu_read_lock();
269 ca = rcu_dereference(net->ipv4.tcp_congestion_control);
270 strncpy(name, ca->name, TCP_CA_NAME_MAX);
271 rcu_read_unlock();
272 }
273
274
275 void tcp_get_allowed_congestion_control(char *buf, size_t maxlen)
276 {
277 struct tcp_congestion_ops *ca;
278 size_t offs = 0;
279
280 *buf = '\0';
281 rcu_read_lock();
282 list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
283 if (!(ca->flags & TCP_CONG_NON_RESTRICTED))
284 continue;
285 offs += snprintf(buf + offs, maxlen - offs,
286 "%s%s",
287 offs == 0 ? "" : " ", ca->name);
288 }
289 rcu_read_unlock();
290 }
291
292
293 int tcp_set_allowed_congestion_control(char *val)
294 {
295 struct tcp_congestion_ops *ca;
296 char *saved_clone, *clone, *name;
297 int ret = 0;
298
299 saved_clone = clone = kstrdup(val, GFP_USER);
300 if (!clone)
301 return -ENOMEM;
302
303 spin_lock(&tcp_cong_list_lock);
304
305 while ((name = strsep(&clone, " ")) && *name) {
306 ca = tcp_ca_find(name);
307 if (!ca) {
308 ret = -ENOENT;
309 goto out;
310 }
311 }
312
313
314 list_for_each_entry_rcu(ca, &tcp_cong_list, list)
315 ca->flags &= ~TCP_CONG_NON_RESTRICTED;
316
317
318 while ((name = strsep(&val, " ")) && *name) {
319 ca = tcp_ca_find(name);
320 WARN_ON(!ca);
321 if (ca)
322 ca->flags |= TCP_CONG_NON_RESTRICTED;
323 }
324 out:
325 spin_unlock(&tcp_cong_list_lock);
326 kfree(saved_clone);
327
328 return ret;
329 }
330
331
332
333
334
335
336 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
337 bool reinit, bool cap_net_admin)
338 {
339 struct inet_connection_sock *icsk = inet_csk(sk);
340 const struct tcp_congestion_ops *ca;
341 int err = 0;
342
343 if (icsk->icsk_ca_dst_locked)
344 return -EPERM;
345
346 rcu_read_lock();
347 if (!load)
348 ca = tcp_ca_find(name);
349 else
350 ca = tcp_ca_find_autoload(sock_net(sk), name);
351
352
353 if (ca == icsk->icsk_ca_ops) {
354 icsk->icsk_ca_setsockopt = 1;
355 goto out;
356 }
357
358 if (!ca) {
359 err = -ENOENT;
360 } else if (!load) {
361 const struct tcp_congestion_ops *old_ca = icsk->icsk_ca_ops;
362
363 if (try_module_get(ca->owner)) {
364 if (reinit) {
365 tcp_reinit_congestion_control(sk, ca);
366 } else {
367 icsk->icsk_ca_ops = ca;
368 module_put(old_ca->owner);
369 }
370 } else {
371 err = -EBUSY;
372 }
373 } else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || cap_net_admin)) {
374 err = -EPERM;
375 } else if (!try_module_get(ca->owner)) {
376 err = -EBUSY;
377 } else {
378 tcp_reinit_congestion_control(sk, ca);
379 }
380 out:
381 rcu_read_unlock();
382 return err;
383 }
384
385
386
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388
389
390
391
392
393
394 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked)
395 {
396 u32 cwnd = min(tp->snd_cwnd + acked, tp->snd_ssthresh);
397
398 acked -= cwnd - tp->snd_cwnd;
399 tp->snd_cwnd = min(cwnd, tp->snd_cwnd_clamp);
400
401 return acked;
402 }
403 EXPORT_SYMBOL_GPL(tcp_slow_start);
404
405
406
407
408 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked)
409 {
410
411 if (tp->snd_cwnd_cnt >= w) {
412 tp->snd_cwnd_cnt = 0;
413 tp->snd_cwnd++;
414 }
415
416 tp->snd_cwnd_cnt += acked;
417 if (tp->snd_cwnd_cnt >= w) {
418 u32 delta = tp->snd_cwnd_cnt / w;
419
420 tp->snd_cwnd_cnt -= delta * w;
421 tp->snd_cwnd += delta;
422 }
423 tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_cwnd_clamp);
424 }
425 EXPORT_SYMBOL_GPL(tcp_cong_avoid_ai);
426
427
428
429
430
431
432
433
434 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked)
435 {
436 struct tcp_sock *tp = tcp_sk(sk);
437
438 if (!tcp_is_cwnd_limited(sk))
439 return;
440
441
442 if (tcp_in_slow_start(tp)) {
443 acked = tcp_slow_start(tp, acked);
444 if (!acked)
445 return;
446 }
447
448 tcp_cong_avoid_ai(tp, tp->snd_cwnd, acked);
449 }
450 EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid);
451
452
453 u32 tcp_reno_ssthresh(struct sock *sk)
454 {
455 const struct tcp_sock *tp = tcp_sk(sk);
456
457 return max(tp->snd_cwnd >> 1U, 2U);
458 }
459 EXPORT_SYMBOL_GPL(tcp_reno_ssthresh);
460
461 u32 tcp_reno_undo_cwnd(struct sock *sk)
462 {
463 const struct tcp_sock *tp = tcp_sk(sk);
464
465 return max(tp->snd_cwnd, tp->prior_cwnd);
466 }
467 EXPORT_SYMBOL_GPL(tcp_reno_undo_cwnd);
468
469 struct tcp_congestion_ops tcp_reno = {
470 .flags = TCP_CONG_NON_RESTRICTED,
471 .name = "reno",
472 .owner = THIS_MODULE,
473 .ssthresh = tcp_reno_ssthresh,
474 .cong_avoid = tcp_reno_cong_avoid,
475 .undo_cwnd = tcp_reno_undo_cwnd,
476 };