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8
9#define pr_fmt(fmt) "TCP: " fmt
10
11#include <linux/module.h>
12#include <linux/mm.h>
13#include <linux/types.h>
14#include <linux/list.h>
15#include <linux/gfp.h>
16#include <net/tcp.h>
17
18int sysctl_tcp_max_ssthresh = 0;
19
20static DEFINE_SPINLOCK(tcp_cong_list_lock);
21static LIST_HEAD(tcp_cong_list);
22
23
24static 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
38
39
40int tcp_register_congestion_control(struct tcp_congestion_ops *ca)
41{
42 int ret = 0;
43
44
45 if (!ca->ssthresh || !ca->cong_avoid) {
46 pr_err("%s does not implement required ops\n", ca->name);
47 return -EINVAL;
48 }
49
50 spin_lock(&tcp_cong_list_lock);
51 if (tcp_ca_find(ca->name)) {
52 pr_notice("%s already registered\n", ca->name);
53 ret = -EEXIST;
54 } else {
55 list_add_tail_rcu(&ca->list, &tcp_cong_list);
56 pr_info("%s registered\n", ca->name);
57 }
58 spin_unlock(&tcp_cong_list_lock);
59
60 return ret;
61}
62EXPORT_SYMBOL_GPL(tcp_register_congestion_control);
63
64
65
66
67
68
69
70void tcp_unregister_congestion_control(struct tcp_congestion_ops *ca)
71{
72 spin_lock(&tcp_cong_list_lock);
73 list_del_rcu(&ca->list);
74 spin_unlock(&tcp_cong_list_lock);
75}
76EXPORT_SYMBOL_GPL(tcp_unregister_congestion_control);
77
78
79void tcp_init_congestion_control(struct sock *sk)
80{
81 struct inet_connection_sock *icsk = inet_csk(sk);
82 struct tcp_congestion_ops *ca;
83
84
85 if (icsk->icsk_ca_ops == &tcp_init_congestion_ops) {
86 rcu_read_lock();
87 list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
88 if (try_module_get(ca->owner)) {
89 icsk->icsk_ca_ops = ca;
90 break;
91 }
92
93
94 }
95 rcu_read_unlock();
96 }
97
98 if (icsk->icsk_ca_ops->init)
99 icsk->icsk_ca_ops->init(sk);
100}
101
102
103void tcp_cleanup_congestion_control(struct sock *sk)
104{
105 struct inet_connection_sock *icsk = inet_csk(sk);
106
107 if (icsk->icsk_ca_ops->release)
108 icsk->icsk_ca_ops->release(sk);
109 module_put(icsk->icsk_ca_ops->owner);
110}
111
112
113int tcp_set_default_congestion_control(const char *name)
114{
115 struct tcp_congestion_ops *ca;
116 int ret = -ENOENT;
117
118 spin_lock(&tcp_cong_list_lock);
119 ca = tcp_ca_find(name);
120#ifdef CONFIG_MODULES
121 if (!ca && capable(CAP_NET_ADMIN)) {
122 spin_unlock(&tcp_cong_list_lock);
123
124 request_module("tcp_%s", name);
125 spin_lock(&tcp_cong_list_lock);
126 ca = tcp_ca_find(name);
127 }
128#endif
129
130 if (ca) {
131 ca->flags |= TCP_CONG_NON_RESTRICTED;
132 list_move(&ca->list, &tcp_cong_list);
133 ret = 0;
134 }
135 spin_unlock(&tcp_cong_list_lock);
136
137 return ret;
138}
139
140
141static int __init tcp_congestion_default(void)
142{
143 return tcp_set_default_congestion_control(CONFIG_DEFAULT_TCP_CONG);
144}
145late_initcall(tcp_congestion_default);
146
147
148
149void tcp_get_available_congestion_control(char *buf, size_t maxlen)
150{
151 struct tcp_congestion_ops *ca;
152 size_t offs = 0;
153
154 rcu_read_lock();
155 list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
156 offs += snprintf(buf + offs, maxlen - offs,
157 "%s%s",
158 offs == 0 ? "" : " ", ca->name);
159
160 }
161 rcu_read_unlock();
162}
163
164
165void tcp_get_default_congestion_control(char *name)
166{
167 struct tcp_congestion_ops *ca;
168
169 BUG_ON(list_empty(&tcp_cong_list));
170
171 rcu_read_lock();
172 ca = list_entry(tcp_cong_list.next, struct tcp_congestion_ops, list);
173 strncpy(name, ca->name, TCP_CA_NAME_MAX);
174 rcu_read_unlock();
175}
176
177
178void tcp_get_allowed_congestion_control(char *buf, size_t maxlen)
179{
180 struct tcp_congestion_ops *ca;
181 size_t offs = 0;
182
183 *buf = '\0';
184 rcu_read_lock();
185 list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
186 if (!(ca->flags & TCP_CONG_NON_RESTRICTED))
187 continue;
188 offs += snprintf(buf + offs, maxlen - offs,
189 "%s%s",
190 offs == 0 ? "" : " ", ca->name);
191
192 }
193 rcu_read_unlock();
194}
195
196
197int tcp_set_allowed_congestion_control(char *val)
198{
199 struct tcp_congestion_ops *ca;
200 char *saved_clone, *clone, *name;
201 int ret = 0;
202
203 saved_clone = clone = kstrdup(val, GFP_USER);
204 if (!clone)
205 return -ENOMEM;
206
207 spin_lock(&tcp_cong_list_lock);
208
209 while ((name = strsep(&clone, " ")) && *name) {
210 ca = tcp_ca_find(name);
211 if (!ca) {
212 ret = -ENOENT;
213 goto out;
214 }
215 }
216
217
218 list_for_each_entry_rcu(ca, &tcp_cong_list, list)
219 ca->flags &= ~TCP_CONG_NON_RESTRICTED;
220
221
222 while ((name = strsep(&val, " ")) && *name) {
223 ca = tcp_ca_find(name);
224 WARN_ON(!ca);
225 if (ca)
226 ca->flags |= TCP_CONG_NON_RESTRICTED;
227 }
228out:
229 spin_unlock(&tcp_cong_list_lock);
230 kfree(saved_clone);
231
232 return ret;
233}
234
235
236
237int tcp_set_congestion_control(struct sock *sk, const char *name)
238{
239 struct inet_connection_sock *icsk = inet_csk(sk);
240 struct tcp_congestion_ops *ca;
241 int err = 0;
242
243 rcu_read_lock();
244 ca = tcp_ca_find(name);
245
246
247 if (ca == icsk->icsk_ca_ops)
248 goto out;
249
250#ifdef CONFIG_MODULES
251
252 if (!ca && capable(CAP_NET_ADMIN)) {
253 rcu_read_unlock();
254 request_module("tcp_%s", name);
255 rcu_read_lock();
256 ca = tcp_ca_find(name);
257 }
258#endif
259 if (!ca)
260 err = -ENOENT;
261
262 else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || capable(CAP_NET_ADMIN)))
263 err = -EPERM;
264
265 else if (!try_module_get(ca->owner))
266 err = -EBUSY;
267
268 else {
269 tcp_cleanup_congestion_control(sk);
270 icsk->icsk_ca_ops = ca;
271
272 if (sk->sk_state != TCP_CLOSE && icsk->icsk_ca_ops->init)
273 icsk->icsk_ca_ops->init(sk);
274 }
275 out:
276 rcu_read_unlock();
277 return err;
278}
279
280
281
282
283bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight)
284{
285 const struct tcp_sock *tp = tcp_sk(sk);
286 u32 left;
287
288 if (in_flight >= tp->snd_cwnd)
289 return true;
290
291 left = tp->snd_cwnd - in_flight;
292 if (sk_can_gso(sk) &&
293 left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd &&
294 left * tp->mss_cache < sk->sk_gso_max_size &&
295 left < sk->sk_gso_max_segs)
296 return true;
297 return left <= tcp_max_tso_deferred_mss(tp);
298}
299EXPORT_SYMBOL_GPL(tcp_is_cwnd_limited);
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306
307
308void tcp_slow_start(struct tcp_sock *tp)
309{
310 int cnt;
311 unsigned int delta = 0;
312
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317
318
319
320 if (sysctl_tcp_abc && tp->bytes_acked < tp->mss_cache)
321 return;
322
323 if (sysctl_tcp_max_ssthresh > 0 && tp->snd_cwnd > sysctl_tcp_max_ssthresh)
324 cnt = sysctl_tcp_max_ssthresh >> 1;
325 else
326 cnt = tp->snd_cwnd;
327
328
329
330
331 if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache)
332 cnt <<= 1;
333 tp->bytes_acked = 0;
334
335 tp->snd_cwnd_cnt += cnt;
336 while (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
337 tp->snd_cwnd_cnt -= tp->snd_cwnd;
338 delta++;
339 }
340 tp->snd_cwnd = min(tp->snd_cwnd + delta, tp->snd_cwnd_clamp);
341}
342EXPORT_SYMBOL_GPL(tcp_slow_start);
343
344
345void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w)
346{
347 if (tp->snd_cwnd_cnt >= w) {
348 if (tp->snd_cwnd < tp->snd_cwnd_clamp)
349 tp->snd_cwnd++;
350 tp->snd_cwnd_cnt = 0;
351 } else {
352 tp->snd_cwnd_cnt++;
353 }
354}
355EXPORT_SYMBOL_GPL(tcp_cong_avoid_ai);
356
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363
364void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
365{
366 struct tcp_sock *tp = tcp_sk(sk);
367
368 if (!tcp_is_cwnd_limited(sk, in_flight))
369 return;
370
371
372 if (tp->snd_cwnd <= tp->snd_ssthresh)
373 tcp_slow_start(tp);
374
375
376 else if (sysctl_tcp_abc) {
377
378
379
380 if (tp->bytes_acked >= tp->snd_cwnd*tp->mss_cache) {
381 tp->bytes_acked -= tp->snd_cwnd*tp->mss_cache;
382 if (tp->snd_cwnd < tp->snd_cwnd_clamp)
383 tp->snd_cwnd++;
384 }
385 } else {
386 tcp_cong_avoid_ai(tp, tp->snd_cwnd);
387 }
388}
389EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid);
390
391
392u32 tcp_reno_ssthresh(struct sock *sk)
393{
394 const struct tcp_sock *tp = tcp_sk(sk);
395 return max(tp->snd_cwnd >> 1U, 2U);
396}
397EXPORT_SYMBOL_GPL(tcp_reno_ssthresh);
398
399
400u32 tcp_reno_min_cwnd(const struct sock *sk)
401{
402 const struct tcp_sock *tp = tcp_sk(sk);
403 return tp->snd_ssthresh/2;
404}
405EXPORT_SYMBOL_GPL(tcp_reno_min_cwnd);
406
407struct tcp_congestion_ops tcp_reno = {
408 .flags = TCP_CONG_NON_RESTRICTED,
409 .name = "reno",
410 .owner = THIS_MODULE,
411 .ssthresh = tcp_reno_ssthresh,
412 .cong_avoid = tcp_reno_cong_avoid,
413 .min_cwnd = tcp_reno_min_cwnd,
414};
415
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417
418
419
420struct tcp_congestion_ops tcp_init_congestion_ops = {
421 .name = "",
422 .owner = THIS_MODULE,
423 .ssthresh = tcp_reno_ssthresh,
424 .cong_avoid = tcp_reno_cong_avoid,
425 .min_cwnd = tcp_reno_min_cwnd,
426};
427EXPORT_SYMBOL_GPL(tcp_init_congestion_ops);
428