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24#include <linux/mm.h>
25#include <linux/module.h>
26#include <linux/skbuff.h>
27#include <linux/inet_diag.h>
28#include <net/tcp.h>
29
30
31struct westwood {
32 u32 bw_ns_est;
33 u32 bw_est;
34 u32 rtt_win_sx;
35 u32 bk;
36 u32 snd_una;
37 u32 cumul_ack;
38 u32 accounted;
39 u32 rtt;
40 u32 rtt_min;
41 u8 first_ack;
42 u8 reset_rtt_min;
43};
44
45
46#define TCP_WESTWOOD_RTT_MIN (HZ/20)
47#define TCP_WESTWOOD_INIT_RTT (20*HZ)
48
49
50
51
52
53
54
55
56
57
58
59
60static void tcp_westwood_init(struct sock *sk)
61{
62 struct westwood *w = inet_csk_ca(sk);
63
64 w->bk = 0;
65 w->bw_ns_est = 0;
66 w->bw_est = 0;
67 w->accounted = 0;
68 w->cumul_ack = 0;
69 w->reset_rtt_min = 1;
70 w->rtt_min = w->rtt = TCP_WESTWOOD_INIT_RTT;
71 w->rtt_win_sx = tcp_time_stamp;
72 w->snd_una = tcp_sk(sk)->snd_una;
73 w->first_ack = 1;
74}
75
76
77
78
79
80static inline u32 westwood_do_filter(u32 a, u32 b)
81{
82 return ((7 * a) + b) >> 3;
83}
84
85static void westwood_filter(struct westwood *w, u32 delta)
86{
87
88 if (w->bw_ns_est == 0 && w->bw_est == 0) {
89 w->bw_ns_est = w->bk / delta;
90 w->bw_est = w->bw_ns_est;
91 } else {
92 w->bw_ns_est = westwood_do_filter(w->bw_ns_est, w->bk / delta);
93 w->bw_est = westwood_do_filter(w->bw_est, w->bw_ns_est);
94 }
95}
96
97
98
99
100
101
102static void tcp_westwood_pkts_acked(struct sock *sk, u32 cnt, s32 rtt)
103{
104 struct westwood *w = inet_csk_ca(sk);
105
106 if (rtt > 0)
107 w->rtt = usecs_to_jiffies(rtt);
108}
109
110
111
112
113
114
115static void westwood_update_window(struct sock *sk)
116{
117 struct westwood *w = inet_csk_ca(sk);
118 s32 delta = tcp_time_stamp - w->rtt_win_sx;
119
120
121
122
123
124 if (w->first_ack) {
125 w->snd_una = tcp_sk(sk)->snd_una;
126 w->first_ack = 0;
127 }
128
129
130
131
132
133
134
135
136
137
138 if (w->rtt && delta > max_t(u32, w->rtt, TCP_WESTWOOD_RTT_MIN)) {
139 westwood_filter(w, delta);
140
141 w->bk = 0;
142 w->rtt_win_sx = tcp_time_stamp;
143 }
144}
145
146static inline void update_rtt_min(struct westwood *w)
147{
148 if (w->reset_rtt_min) {
149 w->rtt_min = w->rtt;
150 w->reset_rtt_min = 0;
151 } else
152 w->rtt_min = min(w->rtt, w->rtt_min);
153}
154
155
156
157
158
159
160
161static inline void westwood_fast_bw(struct sock *sk)
162{
163 const struct tcp_sock *tp = tcp_sk(sk);
164 struct westwood *w = inet_csk_ca(sk);
165
166 westwood_update_window(sk);
167
168 w->bk += tp->snd_una - w->snd_una;
169 w->snd_una = tp->snd_una;
170 update_rtt_min(w);
171}
172
173
174
175
176
177
178static inline u32 westwood_acked_count(struct sock *sk)
179{
180 const struct tcp_sock *tp = tcp_sk(sk);
181 struct westwood *w = inet_csk_ca(sk);
182
183 w->cumul_ack = tp->snd_una - w->snd_una;
184
185
186
187
188 if (!w->cumul_ack) {
189 w->accounted += tp->mss_cache;
190 w->cumul_ack = tp->mss_cache;
191 }
192
193 if (w->cumul_ack > tp->mss_cache) {
194
195 if (w->accounted >= w->cumul_ack) {
196 w->accounted -= w->cumul_ack;
197 w->cumul_ack = tp->mss_cache;
198 } else {
199 w->cumul_ack -= w->accounted;
200 w->accounted = 0;
201 }
202 }
203
204 w->snd_una = tp->snd_una;
205
206 return w->cumul_ack;
207}
208
209
210
211
212
213
214
215static u32 tcp_westwood_bw_rttmin(const struct sock *sk)
216{
217 const struct tcp_sock *tp = tcp_sk(sk);
218 const struct westwood *w = inet_csk_ca(sk);
219
220 return max_t(u32, (w->bw_est * w->rtt_min) / tp->mss_cache, 2);
221}
222
223static void tcp_westwood_ack(struct sock *sk, u32 ack_flags)
224{
225 if (ack_flags & CA_ACK_SLOWPATH) {
226 struct westwood *w = inet_csk_ca(sk);
227
228 westwood_update_window(sk);
229 w->bk += westwood_acked_count(sk);
230
231 update_rtt_min(w);
232 return;
233 }
234
235 westwood_fast_bw(sk);
236}
237
238static void tcp_westwood_event(struct sock *sk, enum tcp_ca_event event)
239{
240 struct tcp_sock *tp = tcp_sk(sk);
241 struct westwood *w = inet_csk_ca(sk);
242
243 switch (event) {
244 case CA_EVENT_COMPLETE_CWR:
245 tp->snd_cwnd = tp->snd_ssthresh = tcp_westwood_bw_rttmin(sk);
246 break;
247 case CA_EVENT_LOSS:
248 tp->snd_ssthresh = tcp_westwood_bw_rttmin(sk);
249
250 w->reset_rtt_min = 1;
251 break;
252 default:
253
254 break;
255 }
256}
257
258
259static size_t tcp_westwood_info(struct sock *sk, u32 ext, int *attr,
260 union tcp_cc_info *info)
261{
262 const struct westwood *ca = inet_csk_ca(sk);
263
264 if (ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
265 info->vegas.tcpv_enabled = 1;
266 info->vegas.tcpv_rttcnt = 0;
267 info->vegas.tcpv_rtt = jiffies_to_usecs(ca->rtt),
268 info->vegas.tcpv_minrtt = jiffies_to_usecs(ca->rtt_min),
269
270 *attr = INET_DIAG_VEGASINFO;
271 return sizeof(struct tcpvegas_info);
272 }
273 return 0;
274}
275
276static struct tcp_congestion_ops tcp_westwood __read_mostly = {
277 .init = tcp_westwood_init,
278 .ssthresh = tcp_reno_ssthresh,
279 .cong_avoid = tcp_reno_cong_avoid,
280 .cwnd_event = tcp_westwood_event,
281 .in_ack_event = tcp_westwood_ack,
282 .get_info = tcp_westwood_info,
283 .pkts_acked = tcp_westwood_pkts_acked,
284
285 .owner = THIS_MODULE,
286 .name = "westwood"
287};
288
289static int __init tcp_westwood_register(void)
290{
291 BUILD_BUG_ON(sizeof(struct westwood) > ICSK_CA_PRIV_SIZE);
292 return tcp_register_congestion_control(&tcp_westwood);
293}
294
295static void __exit tcp_westwood_unregister(void)
296{
297 tcp_unregister_congestion_control(&tcp_westwood);
298}
299
300module_init(tcp_westwood_register);
301module_exit(tcp_westwood_unregister);
302
303MODULE_AUTHOR("Stephen Hemminger, Angelo Dell'Aera");
304MODULE_LICENSE("GPL");
305MODULE_DESCRIPTION("TCP Westwood+");
306